diff --git a/cmd/gateway_agents.go b/cmd/gateway_agents.go
index 60e76281..27703d20 100644
--- a/cmd/gateway_agents.go
+++ b/cmd/gateway_agents.go
@@ -213,6 +213,7 @@ func setupSubagents(providerReg *providers.Registry, cfg *config.Config, msgBus
 
 	manager := tools.NewSubagentManager(provider, providerReg, agentCfg.Model, msgBus, toolsFactory, subCfg)
 	manager.SetUsageCapService(usageCapSvc)
+	manager.SetAgentBudget(agentCfg.ContextWindow, agentCfg.MaxTokens)
 	return manager
 }
 
diff --git a/cmd/gateway_consumer_normal.go b/cmd/gateway_consumer_normal.go
index 73056f89..e88328fd 100644
--- a/cmd/gateway_consumer_normal.go
+++ b/cmd/gateway_consumer_normal.go
@@ -61,6 +61,12 @@ func processNormalMessage(
 		})
 		return
 	}
+	// Team Work and intent gates run before Loop.injectContext. Propagate the
+	// resolved agent budget here so every classifier sees the same authority.
+	ctx = agent.WithAgentBudget(ctx, agentLoop)
+	if uid := agentLoop.UUID(); uid != uuid.Nil {
+		ctx = store.WithAgentID(ctx, uid)
+	}
 
 	// Build session key based on scope config (matching TS buildAgentPeerSessionKey).
 	peerKind := msg.PeerKind
diff --git a/internal/agent/loop_compact.go b/internal/agent/loop_compact.go
index 28b0bad2..4b5e0cfc 100644
--- a/internal/agent/loop_compact.go
+++ b/internal/agent/loop_compact.go
@@ -2,6 +2,7 @@ package agent
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"log/slog"
 	"strings"
@@ -39,6 +40,12 @@ Conversation to summarize:
 
 const defaultCompactionTimeout = 120 * time.Second
 
+const (
+	maxCompactionChunks      = 16
+	maxCompactionMergeLevels = 3
+	defaultCompactionShare   = 0.85
+)
+
 func (l *Loop) compactionTimeout() time.Duration {
 	if l.compactionCfg != nil && l.compactionCfg.TimeoutSeconds > 0 {
 		return time.Duration(l.compactionCfg.TimeoutSeconds) * time.Second
@@ -81,43 +88,30 @@ func (l *Loop) compactMessagesInPlace(ctx context.Context, messages []providers.
 		return nil
 	}
 
-	// Build summary input (same pattern as maybeSummarize in loop_history.go).
 	toSummarize := messages[:splitIdx]
-	var sb strings.Builder
-	for _, m := range toSummarize {
-		switch m.Role {
-		case "user":
-			fmt.Fprintf(&sb, "user: %s\n", m.Content)
-		case "assistant":
-			fmt.Fprintf(&sb, "assistant: %s\n", SanitizeAssistantContent(m.Content))
-		}
-	}
-
 	timeout := l.compactionTimeout()
 	sctx, cancel := context.WithTimeout(ctx, timeout)
 	defer cancel()
 
-	inTokens := l.estimateSummaryInputTokens(toSummarize)
-	slog.Info("compact_budget",
-		"path", "mid-loop",
-		"agent", l.id,
-		"in_tokens", inTokens,
-		"out_tokens", dynamicSummaryMax(inTokens),
-		"timeout_seconds", int(timeout/time.Second),
-	)
-	chatReq := providers.ChatRequest{
-		Messages: []providers.Message{{
-			Role:    "user",
-			Content: compactionSummaryPrompt + sb.String(),
-		}},
-		Model:   l.model,
-		Options: map[string]any{"max_tokens": dynamicSummaryMax(inTokens), "temperature": 0.3},
+	inputCap := l.compactionInputCap()
+	if inputCap <= 0 {
+		slog.Warn("mid_loop_compaction_failed", "agent", l.id, "error", "context_window_unresolved")
+		return nil
 	}
-	resp, err := l.callInternalLLMWithUsage(sctx, chatReq, "mid-loop-compaction")
+	units := buildCompactionUnits(toSummarize)
+	summaryContent, chunkCount, err := l.summarizeCompactionUnits(sctx, units, inputCap, 1)
 	if err != nil {
 		slog.Warn("mid_loop_compaction_failed", "agent", l.id, "timeout_seconds", int(timeout/time.Second), "error", err)
 		return nil
 	}
+	slog.Info("compact_budget",
+		"path", "mid-loop",
+		"agent", l.id,
+		"in_tokens", l.estimateSummaryInputTokens(toSummarize),
+		"input_cap_tokens", inputCap,
+		"chunks", chunkCount,
+		"timeout_seconds", int(timeout/time.Second),
+	)
 
 	// Collect MediaRefs from compacted messages (keep up to 30 most recent).
 	const maxPreservedMediaRefs = 30
@@ -133,7 +127,7 @@ func (l *Loop) compactMessagesInPlace(ctx context.Context, messages []providers.
 
 	summary := providers.Message{
 		Role:      "user",
-		Content:   "[Summary of earlier conversation]\n" + SanitizeAssistantContent(resp.Content),
+		Content:   "[Summary of earlier conversation]\n" + summaryContent,
 		MediaRefs: preservedRefs,
 	}
 	result := make([]providers.Message, 0, 1+keepCount)
@@ -149,6 +143,211 @@ func (l *Loop) compactMessagesInPlace(ctx context.Context, messages []providers.
 	return result
 }
 
+func (l *Loop) compactionInputCap() int {
+	contextWindow := l.resolveEffectiveContextWindow()
+	if contextWindow <= 0 {
+		return 0
+	}
+	maxTokens := l.effectiveMaxTokens()
+	hardInputCap := contextWindow - maxTokens
+	share := defaultCompactionShare
+	if l.compactionCfg != nil && l.compactionCfg.MaxRequestShare > 0 && l.compactionCfg.MaxRequestShare <= 1 {
+		share = l.compactionCfg.MaxRequestShare
+	}
+	softTarget := int(float64(contextWindow)*share) - maxTokens
+	return min(hardInputCap, softTarget)
+}
+
+func buildCompactionUnits(messages []providers.Message) []string {
+	units := make([]string, 0, len(messages))
+	for i := 0; i < len(messages); {
+		end := i + 1
+		if messages[i].Role == "assistant" && len(messages[i].ToolCalls) > 0 {
+			for end < len(messages) && messages[end].Role == "tool" {
+				end++
+			}
+		}
+		if text := renderCompactionMessages(messages[i:end]); text != "" {
+			units = append(units, text)
+		}
+		i = end
+	}
+	return units
+}
+
+func renderCompactionMessages(messages []providers.Message) string {
+	var sb strings.Builder
+	for _, m := range messages {
+		switch m.Role {
+		case "user":
+			fmt.Fprintf(&sb, "user: %s\n", m.Content)
+		case "assistant":
+			if content := SanitizeAssistantContent(m.Content); content != "" {
+				fmt.Fprintf(&sb, "assistant: %s\n", content)
+			}
+			// Tool calls carry the assistant's intent (which tool, what args);
+			// dropping them loses the "why" behind each tool result below.
+			for _, tc := range m.ToolCalls {
+				if args, err := json.Marshal(tc.Arguments); err == nil && len(tc.Arguments) > 0 {
+					fmt.Fprintf(&sb, "assistant tool call %s(%s)\n", tc.Name, string(args))
+				} else {
+					fmt.Fprintf(&sb, "assistant tool call %s()\n", tc.Name)
+				}
+			}
+		case "tool":
+			// Tool results hold the technical payload the summary must retain
+			// (search hits, file contents, API responses). buildCompactionUnits
+			// groups these with their assistant tool_call; the previous renderer
+			// silently dropped them, erasing the data before summarization.
+			if m.Content != "" {
+				fmt.Fprintf(&sb, "tool result: %s\n", m.Content)
+			}
+		}
+	}
+	return sb.String()
+}
+
+func (l *Loop) summarizeCompactionUnits(ctx context.Context, units []string, inputCap, level int) (string, int, error) {
+	if len(units) == 0 {
+		return "", 0, fmt.Errorf("no compactable conversation content")
+	}
+	chunks, err := l.packCompactionChunks(units, inputCap)
+	if err != nil {
+		return "", 0, err
+	}
+	if len(chunks) > maxCompactionChunks {
+		return "", 0, fmt.Errorf("compaction chunk limit exceeded: chunks=%d limit=%d", len(chunks), maxCompactionChunks)
+	}
+
+	summaries := make([]string, 0, len(chunks))
+	for i, chunk := range chunks {
+		inputTokens := l.estimateCompactionRequestTokens(chunk)
+		if inputTokens > inputCap {
+			return "", 0, fmt.Errorf("compaction chunk exceeds input cap: chunk=%d input=%d cap=%d", i, inputTokens, inputCap)
+		}
+		outputTokens := dynamicSummaryMax(inputTokens)
+		slog.Debug("compact_chunk_budget",
+			"path", "mid-loop",
+			"agent", l.id,
+			"level", level,
+			"chunk", i+1,
+			"chunks", len(chunks),
+			"in_tokens", inputTokens,
+			"out_tokens", outputTokens,
+			"input_cap_tokens", inputCap,
+		)
+		resp, callErr := l.callInternalLLMWithUsage(ctx, providers.ChatRequest{
+			Messages: []providers.Message{{Role: "user", Content: compactionSummaryPrompt + chunk}},
+			Model:    l.model,
+			Options:  map[string]any{"max_tokens": outputTokens, "temperature": 0.3},
+		}, "mid-loop-compaction")
+		if callErr != nil {
+			return "", 0, callErr
+		}
+		summary := SanitizeAssistantContent(resp.Content)
+		if strings.TrimSpace(summary) == "" {
+			return "", 0, fmt.Errorf("compaction returned empty summary")
+		}
+		summaries = append(summaries, summary)
+	}
+	if len(summaries) == 1 {
+		return summaries[0], len(chunks), nil
+	}
+	if level >= maxCompactionMergeLevels {
+		return "", 0, fmt.Errorf("compaction merge level exceeded: level=%d limit=%d", level, maxCompactionMergeLevels)
+	}
+
+	mergeUnits := make([]string, len(summaries))
+	for i, summary := range summaries {
+		mergeUnits[i] = fmt.Sprintf("partial summary %d: %s\n", i+1, summary)
+	}
+	merged, mergeChunks, mergeErr := l.summarizeCompactionUnits(ctx, mergeUnits, inputCap, level+1)
+	return merged, len(chunks) + mergeChunks, mergeErr
+}
+
+func (l *Loop) packCompactionChunks(units []string, inputCap int) ([]string, error) {
+	var chunks []string
+	var current strings.Builder
+	flush := func() {
+		if current.Len() == 0 {
+			return
+		}
+		chunks = append(chunks, current.String())
+		current.Reset()
+	}
+
+	for _, unit := range units {
+		parts, err := l.splitCompactionUnit(unit, inputCap)
+		if err != nil {
+			return nil, err
+		}
+		for _, part := range parts {
+			candidate := current.String() + part
+			if current.Len() > 0 && l.estimateCompactionRequestTokens(candidate) > inputCap {
+				flush()
+				candidate = part
+			}
+			if l.estimateCompactionRequestTokens(candidate) > inputCap {
+				return nil, fmt.Errorf("atomic compaction unit exceeds input cap")
+			}
+			current.WriteString(part)
+			if len(chunks) >= maxCompactionChunks {
+				return nil, fmt.Errorf("compaction chunk limit exceeded: limit=%d", maxCompactionChunks)
+			}
+		}
+	}
+	flush()
+	return chunks, nil
+}
+
+func (l *Loop) splitCompactionUnit(unit string, inputCap int) ([]string, error) {
+	if l.estimateCompactionRequestTokens(unit) <= inputCap {
+		return []string{unit}, nil
+	}
+	words := strings.Fields(unit)
+	if len(words) == 0 {
+		return nil, fmt.Errorf("empty oversized compaction unit")
+	}
+
+	var parts []string
+	var current strings.Builder
+	for _, word := range words {
+		candidate := word
+		if current.Len() > 0 {
+			candidate = current.String() + " " + word
+		}
+		if l.estimateCompactionRequestTokens(candidate) <= inputCap {
+			if current.Len() > 0 {
+				current.WriteByte(' ')
+			}
+			current.WriteString(word)
+			continue
+		}
+		if current.Len() == 0 {
+			return nil, fmt.Errorf("atomic compaction token exceeds input cap")
+		}
+		parts = append(parts, current.String()+"\n")
+		current.Reset()
+		current.WriteString("[continued] ")
+		current.WriteString(word)
+		if l.estimateCompactionRequestTokens(current.String()) > inputCap {
+			return nil, fmt.Errorf("atomic compaction token exceeds input cap")
+		}
+	}
+	if current.Len() > 0 {
+		parts = append(parts, current.String()+"\n")
+	}
+	return parts, nil
+}
+
+func (l *Loop) estimateCompactionRequestTokens(content string) int {
+	message := providers.Message{Role: "user", Content: compactionSummaryPrompt + content}
+	if l.tokenCounter != nil {
+		return l.tokenCounter.CountMessages(l.model, []providers.Message{message})
+	}
+	return len([]rune(message.Content))/3 + 4
+}
+
 // dynamicSummaryMax returns the output-token budget for a compaction or
 // summarization call, scaled to input size. Formula: in/25 (~4% compression),
 // clamped to [1024, 8192]. Floor keeps short summaries coherent; cap prevents
diff --git a/internal/agent/loop_compact_integration_test.go b/internal/agent/loop_compact_integration_test.go
index 305b0856..8b5f7c07 100644
--- a/internal/agent/loop_compact_integration_test.go
+++ b/internal/agent/loop_compact_integration_test.go
@@ -47,9 +47,10 @@ func TestLoopCompact_Integration_DynamicMaxTokens_VietnameseFixture(t *testing.T
 	cap := &capturingProvider{response: "Tóm tắt cuộc trò chuyện: Đã thảo luận về nhiều chủ đề."}
 
 	loop := &Loop{
-		provider:     cap,
-		model:        "claude-3-5-sonnet",
-		tokenCounter: tokencount.NewFallbackCounter(),
+		provider:      cap,
+		model:         "claude-3-5-sonnet",
+		tokenCounter:  tokencount.NewFallbackCounter(),
+		contextWindow: 200_000,
 	}
 
 	// 600 messages × ~500 runes each ≈ 300k runes ÷ 3 ≈ 100k tokens total.
@@ -97,3 +98,105 @@ func TestLoopCompact_Integration_DynamicMaxTokens_VietnameseFixture(t *testing.T
 	t.Logf("observed: msgs=%d splitIdx=%d estimatedIn=%d max_tokens=%d dynamicSummaryMax=%d",
 		len(msgs), splitIdx, estimatedIn, maxTokens, dynamicSummaryMax(estimatedIn))
 }
+
+func TestLoopCompact_ChunksEverySummaryRequestUnderAgentCap(t *testing.T) {
+	cap := &capturingProvider{response: "bounded summary"}
+	loop := &Loop{
+		provider:      cap,
+		model:         "claude-3-5-sonnet",
+		tokenCounter:  tokencount.NewFallbackCounter(),
+		contextWindow: 20_000,
+	}
+	msgs := buildVietnameseMsgs(20, 4_000)
+
+	result := loop.compactMessagesInPlace(context.Background(), msgs)
+	if result == nil {
+		t.Fatal("compactMessagesInPlace returned nil")
+	}
+	if len(cap.captured) < 3 {
+		t.Fatalf("provider calls = %d, want multiple chunks plus merge", len(cap.captured))
+	}
+	inputCap := loop.compactionInputCap()
+	for i, req := range cap.captured {
+		got := loop.tokenCounter.CountMessages(loop.model, req.Messages)
+		if got > inputCap {
+			t.Fatalf("request %d input = %d, exceeds cap %d", i, got, inputCap)
+		}
+	}
+}
+
+// TestLoopCompact_InputCapReservesFixedMaxTokens locks the agent-only budget:
+// compactionInputCap() reserves the CALLING agent's fixed effectiveMaxTokens()
+// from the window, bounded by the request share. The dynamic-output term
+// (dynamicSummaryMax) governs only the per-chunk output budget — it is NOT an
+// authority over the input cap, so it does not appear here.
+func TestLoopCompact_InputCapReservesFixedMaxTokens(t *testing.T) {
+	const (
+		window    = 20_000
+		maxTokens = 8_192
+	)
+	loop := &Loop{
+		provider:      &capturingProvider{},
+		model:         "claude-3-5-sonnet",
+		contextWindow: window,
+		maxTokens:     maxTokens,
+	}
+	inputCap := loop.compactionInputCap()
+
+	hardCap := window - maxTokens                                         // 11808
+	softTarget := int(float64(window)*defaultCompactionShare) - maxTokens // 8808
+	want := min(hardCap, softTarget)
+	if inputCap != want {
+		t.Fatalf("compactionInputCap() = %d, want %d (min(window-maxTokens, share*window-maxTokens))", inputCap, want)
+	}
+	// Invariant: input cap plus the fixed reserve never exceeds the window.
+	if inputCap+maxTokens > window {
+		t.Fatalf("inputCap %d + reserve %d exceeds window %d", inputCap, maxTokens, window)
+	}
+}
+
+func TestLoopCompact_RejectsMoreThanSixteenChunksBeforeProvider(t *testing.T) {
+	cap := &capturingProvider{response: "unused"}
+	loop := &Loop{
+		provider:      cap,
+		model:         "claude-3-5-sonnet",
+		tokenCounter:  tokencount.NewFallbackCounter(),
+		contextWindow: 200_000,
+	}
+	unit := strings.Repeat("bounded-word ", 1_500)
+	unitCap := loop.estimateCompactionRequestTokens(unit)
+	units := make([]string, maxCompactionChunks+1)
+	for i := range units {
+		units[i] = unit
+	}
+
+	if _, _, err := loop.summarizeCompactionUnits(context.Background(), units, unitCap, 1); err == nil {
+		t.Fatal("expected compaction chunk limit error")
+	}
+	if len(cap.captured) != 0 {
+		t.Fatalf("provider calls = %d, want 0 before chunk-limit rejection", len(cap.captured))
+	}
+}
+
+func TestBuildCompactionUnits_KeepsToolCycleTogether(t *testing.T) {
+	units := buildCompactionUnits([]providers.Message{
+		{Role: "assistant", Content: "calling tool", ToolCalls: []providers.ToolCall{{ID: "call-1", Name: "read_file", Arguments: map[string]any{"path": "a.go"}}}},
+		{Role: "tool", Content: "file body here", ToolCallID: "call-1"},
+		{Role: "user", Content: "continue"},
+	})
+	if len(units) != 2 {
+		t.Fatalf("units = %d, want 2 (tool cycle + following user)", len(units))
+	}
+	if !strings.Contains(units[0], "calling tool") || !strings.Contains(units[1], "continue") {
+		t.Fatalf("unexpected units: %#v", units)
+	}
+	// Regression: the tool RESULT payload and the tool CALL must survive into the
+	// compaction unit. Previously renderCompactionMessages dropped role=tool and
+	// assistant tool_calls, erasing technical data before summarization.
+	if !strings.Contains(units[0], "file body here") {
+		t.Fatalf("tool result dropped from compaction unit: %#v", units[0])
+	}
+	if !strings.Contains(units[0], "read_file") {
+		t.Fatalf("tool call dropped from compaction unit: %#v", units[0])
+	}
+}
diff --git a/internal/agent/loop_compact_max_tokens_test.go b/internal/agent/loop_compact_max_tokens_test.go
index 031feba2..6c803b0c 100644
--- a/internal/agent/loop_compact_max_tokens_test.go
+++ b/internal/agent/loop_compact_max_tokens_test.go
@@ -31,8 +31,9 @@ func TestCompactMessagesInPlace_MaxTokensDynamic(t *testing.T) {
 	cap := &capturingProvider{response: "Summary of conversation."}
 
 	loop := &Loop{
-		provider: cap,
-		model:    "claude-3-5-sonnet",
+		provider:      cap,
+		model:         "claude-3-5-sonnet",
+		contextWindow: 200_000,
 		// tokenCounter nil → estimateSummaryInputTokens uses rune/3 fallback
 	}
 
diff --git a/internal/agent/loop_compact_timeout_test.go b/internal/agent/loop_compact_timeout_test.go
index be1f1b32..8824ee7c 100644
--- a/internal/agent/loop_compact_timeout_test.go
+++ b/internal/agent/loop_compact_timeout_test.go
@@ -25,8 +25,9 @@ func TestCompactMessagesInPlace_UsesDefaultTimeout(t *testing.T) {
 		capturingProvider: capturingProvider{response: "Summary of conversation."},
 	}
 	loop := &Loop{
-		provider: provider,
-		model:    "claude-3-5-sonnet",
+		provider:      provider,
+		model:         "claude-3-5-sonnet",
+		contextWindow: 200_000,
 	}
 
 	start := time.Now()
@@ -43,8 +44,9 @@ func TestCompactMessagesInPlace_UsesConfiguredTimeout(t *testing.T) {
 		capturingProvider: capturingProvider{response: "Summary of conversation."},
 	}
 	loop := &Loop{
-		provider: provider,
-		model:    "claude-3-5-sonnet",
+		provider:      provider,
+		model:         "claude-3-5-sonnet",
+		contextWindow: 200_000,
 		compactionCfg: &config.CompactionConfig{
 			TimeoutSeconds: 45,
 		},
@@ -64,8 +66,9 @@ func TestCompactMessagesInPlace_NonPositiveTimeoutFallsBackToDefault(t *testing.
 		capturingProvider: capturingProvider{response: "Summary of conversation."},
 	}
 	loop := &Loop{
-		provider: provider,
-		model:    "claude-3-5-sonnet",
+		provider:      provider,
+		model:         "claude-3-5-sonnet",
+		contextWindow: 200_000,
 		compactionCfg: &config.CompactionConfig{
 			TimeoutSeconds: -1,
 		},
diff --git a/internal/agent/loop_context.go b/internal/agent/loop_context.go
index fce882f9..b1be7c47 100644
--- a/internal/agent/loop_context.go
+++ b/internal/agent/loop_context.go
@@ -38,6 +38,9 @@ func (l *Loop) injectContext(ctx context.Context, req *RunRequest) (contextSetup
 	if l.tenantID != uuid.Nil {
 		ctx = store.WithTenantID(ctx, l.tenantID)
 	}
+	// Propagate the configured agent budget to every nested model call.
+	ctx = store.WithAgentContextWindow(ctx, l.contextWindow)
+	ctx = store.WithAgentMaxTokens(ctx, l.effectiveMaxTokens())
 	// Inject user ID into context for per-user scoping (memory, context files, etc.)
 	if req.UserID != "" {
 		ctx = store.WithUserID(ctx, req.UserID)
diff --git a/internal/agent/loop_episodic_compaction_test.go b/internal/agent/loop_episodic_compaction_test.go
new file mode 100644
index 00000000..b4006f62
--- /dev/null
+++ b/internal/agent/loop_episodic_compaction_test.go
@@ -0,0 +1,208 @@
+package agent
+
+import (
+	"context"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/google/uuid"
+	"github.com/nextlevelbuilder/goclaw/internal/eventbus"
+)
+
+// recordingBus captures every published DomainEvent for assertion.
+// Distinct from the eventbus package's own test bus — this one does no
+// dispatch, it only records what the emit callback published.
+type recordingBus struct {
+	mu        sync.Mutex
+	published []eventbus.DomainEvent
+}
+
+func (r *recordingBus) Publish(event eventbus.DomainEvent) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	r.published = append(r.published, event)
+}
+func (r *recordingBus) Subscribe(_ eventbus.EventType, _ eventbus.DomainEventHandler) func() {
+	return func() {}
+}
+func (r *recordingBus) Start(_ context.Context)            {}
+func (r *recordingBus) Drain(_ time.Duration) error        { return nil }
+func (r *recordingBus) events() []eventbus.DomainEvent {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	out := make([]eventbus.DomainEvent, len(r.published))
+	copy(out, r.published)
+	return out
+}
+
+// ---------------------------------------------------------------------------
+// V1-A: emit reads the CUMULATIVE session compaction count, not the per-run 0.
+// ---------------------------------------------------------------------------
+
+func TestEmitSessionCompleted_UsesCumulativeCount(t *testing.T) {
+	bus := &recordingBus{}
+	sessions := &nopSessionStore{
+		compactionCount: 5, // cumulative session count
+		summary:         "prior-cycle summary",
+	}
+	loop := &Loop{
+		id:        "test-agent",
+		agentUUID: uuid.New(),
+		tenantID:  uuid.New(),
+		domainBus: bus,
+		sessions:  sessions,
+	}
+
+	loop.emitSessionCompleted(context.Background(), "sess-1", "user-1", 42, 9000)
+
+	evs := bus.events()
+	if len(evs) != 1 {
+		t.Fatalf("published %d events, want 1", len(evs))
+	}
+	ev := evs[0]
+	// Bug A: payload.CompactionCount (the field the worker uses for idempotency)
+	// must be the cumulative count (5), not the per-run 0.
+	pl, ok := ev.Payload.(*eventbus.SessionCompletedPayload)
+	if !ok {
+		t.Fatalf("payload type = %T, want *SessionCompletedPayload", ev.Payload)
+	}
+	if pl.CompactionCount != 5 {
+		t.Errorf("payload.CompactionCount = %d, want 5 (cumulative)", pl.CompactionCount)
+	}
+	// Bug C: SourceID embeds the cumulative count.
+	if ev.SourceID != "sess-1:5" {
+		t.Errorf("SourceID = %q, want %q", ev.SourceID, "sess-1:5")
+	}
+	// Summary from the previous cycle is attached when count > 0.
+	if pl.Summary != "prior-cycle summary" {
+		t.Errorf("payload.Summary = %q, want prior-cycle summary", pl.Summary)
+	}
+	if pl.MessageCount != 42 || pl.TokensUsed != 9000 {
+		t.Errorf("msgCount/tokens = %d/%d, want 42/9000", pl.MessageCount, pl.TokensUsed)
+	}
+}
+
+func TestEmitSessionCompleted_ZeroCountOmitsSummary(t *testing.T) {
+	bus := &recordingBus{}
+	// count == 0 → no prior cycle → summary must NOT be fetched/attached
+	// (worker would otherwise get a stale/empty summary and skip the LLM path).
+	sessions := &nopSessionStore{
+		compactionCount: 0,
+		summary:         "should-not-be-attached",
+	}
+	loop := &Loop{
+		id:        "test-agent",
+		agentUUID: uuid.New(),
+		tenantID:  uuid.New(),
+		domainBus: bus,
+		sessions:  sessions,
+	}
+
+	loop.emitSessionCompleted(context.Background(), "sess-1", "user-1", 1, 100)
+
+	evs := bus.events()
+	if len(evs) != 1 {
+		t.Fatalf("published %d events, want 1", len(evs))
+	}
+	pl := evs[0].Payload.(*eventbus.SessionCompletedPayload)
+	if pl.CompactionCount != 0 {
+		t.Errorf("payload.CompactionCount = %d, want 0", pl.CompactionCount)
+	}
+	if pl.Summary != "" {
+		t.Errorf("payload.Summary = %q, want empty (count==0)", pl.Summary)
+	}
+	if evs[0].SourceID != "sess-1:0" {
+		t.Errorf("SourceID = %q, want sess-1:0", evs[0].SourceID)
+	}
+}
+
+func TestEmitSessionCompleted_NoBusIsNoop(t *testing.T) {
+	loop := &Loop{
+		id:        "test-agent",
+		agentUUID: uuid.New(),
+		tenantID:  uuid.New(),
+		domainBus: nil, // no bus
+		sessions:  &nopSessionStore{compactionCount: 3},
+	}
+	// Must not panic when domainBus is nil.
+	loop.emitSessionCompleted(context.Background(), "sess-1", "user-1", 1, 100)
+}
+
+// ---------------------------------------------------------------------------
+// V1-C: eventbus dedup — distinct counts both pass, same count deduped.
+// Uses the REAL bus + real dedupSet (not the recording double) so we exercise
+// the actual dedup key = Type + ":" + SourceID.
+// ---------------------------------------------------------------------------
+
+func TestEventbusDedup_DistinctCompactionCountsPass(t *testing.T) {
+	bus := eventbus.NewDomainEventBus(eventbus.Config{
+		QueueSize:     100,
+		WorkerCount:   2,
+		RetryAttempts: 1,
+		RetryDelay:    time.Millisecond,
+		DedupTTL:      time.Minute,
+	})
+	bus.Start(context.Background())
+	defer func() { _ = bus.Drain(time.Second) }()
+
+	var mu sync.Mutex
+	var seen []string
+	bus.Subscribe(eventbus.EventSessionCompleted, func(_ context.Context, e eventbus.DomainEvent) error {
+		mu.Lock()
+		seen = append(seen, e.SourceID)
+		mu.Unlock()
+		return nil
+	})
+
+	// Same session, three DIFFERENT compaction cycles → all three must pass dedup.
+	bus.Publish(eventbus.DomainEvent{Type: eventbus.EventSessionCompleted, SourceID: "sess-1:1"})
+	bus.Publish(eventbus.DomainEvent{Type: eventbus.EventSessionCompleted, SourceID: "sess-1:2"})
+	bus.Publish(eventbus.DomainEvent{Type: eventbus.EventSessionCompleted, SourceID: "sess-1:3"})
+	// Rapid duplicate of cycle 2 within TTL → must be deduped.
+	bus.Publish(eventbus.DomainEvent{Type: eventbus.EventSessionCompleted, SourceID: "sess-1:2"})
+
+	time.Sleep(80 * time.Millisecond)
+
+	mu.Lock()
+	got := len(seen)
+	mu.Unlock()
+	if got != 3 {
+		t.Errorf("handler saw %d events, want 3 (cycles 1,2,3; duplicate of 2 deduped)", got)
+	}
+}
+
+func TestEventbusDedup_SameCompactionCountDeduped(t *testing.T) {
+	bus := eventbus.NewDomainEventBus(eventbus.Config{
+		QueueSize:     100,
+		WorkerCount:   2,
+		RetryAttempts: 1,
+		RetryDelay:    time.Millisecond,
+		DedupTTL:      time.Minute,
+	})
+	bus.Start(context.Background())
+	defer func() { _ = bus.Drain(time.Second) }()
+
+	var count int
+	var mu sync.Mutex
+	bus.Subscribe(eventbus.EventSessionCompleted, func(_ context.Context, _ eventbus.DomainEvent) error {
+		mu.Lock()
+		count++
+		mu.Unlock()
+		return nil
+	})
+
+	// Same SourceID (same session, same cycle) published 3× → only 1 passes.
+	for range 3 {
+		bus.Publish(eventbus.DomainEvent{Type: eventbus.EventSessionCompleted, SourceID: "sess-1:7"})
+	}
+
+	time.Sleep(80 * time.Millisecond)
+
+	mu.Lock()
+	got := count
+	mu.Unlock()
+	if got != 1 {
+		t.Errorf("handler called %d times, want 1 (same cycle deduped)", got)
+	}
+}
diff --git a/internal/agent/loop_finalize.go b/internal/agent/loop_finalize.go
index dae304b3..2e42eff1 100644
--- a/internal/agent/loop_finalize.go
+++ b/internal/agent/loop_finalize.go
@@ -2,6 +2,7 @@ package agent
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"path/filepath"
 	"strings"
@@ -186,10 +187,9 @@ func (l *Loop) finalizeRun(
 	l.sessions.UpdateMetadata(ctx, req.SessionKey, l.model, l.provider.Name(), req.Channel)
 	l.sessions.AccumulateTokens(ctx, req.SessionKey, int64(rs.totalUsage.PromptTokens), int64(rs.totalUsage.CompletionTokens))
 
-	// Calibrate token estimation: store actual prompt tokens + message count.
-	if rs.totalUsage.PromptTokens > 0 {
-		msgCount := len(history) + rs.checkpointFlushedMsgs + len(rs.pendingMsgs)
-		l.sessions.SetLastPromptTokens(ctx, req.SessionKey, rs.totalUsage.PromptTokens, msgCount)
+	// Calibrate token estimation using the last LLM request, not the total run.
+	if rs.lastUsage.PromptTokens > 0 && rs.lastUsageMsgCount > 0 {
+		l.sessions.SetLastPromptTokens(ctx, req.SessionKey, rs.lastUsage.PromptTokens, rs.lastUsageMsgCount)
 	}
 
 	l.sessions.Save(ctx, req.SessionKey)
@@ -203,31 +203,43 @@ func (l *Loop) finalizeRun(
 	}
 
 	// 9. Maybe summarize
-	l.maybeSummarize(ctx, req.SessionKey)
+	// Legacy v2 path has no mid-loop pressure signal (that lives in v3 RunState.Prune),
+	// so pass false — this preserves the original baseline-threshold behavior here.
+	l.maybeSummarize(ctx, req.SessionKey, false)
 
 	// V3: emit session.completed for consolidation pipeline (episodic → semantic → dreaming)
 	if l.domainBus != nil {
+		// Bug C parity: include count in SourceID so the eventbus dedup key advances
+		// per compaction cycle (matches the v3 adapter emit path). This path is
+		// currently disabled (FinalizeStage owns finalization) but kept in sync.
+		finalizeCount := l.sessions.GetCompactionCount(ctx, req.SessionKey)
 		l.domainBus.Publish(eventbus.DomainEvent{
 			Type:     eventbus.EventSessionCompleted,
 			TenantID: l.tenantID.String(),
 			AgentID:  l.agentUUID.String(),
 			UserID:   req.UserID,
-			SourceID: req.SessionKey,
+			SourceID: fmt.Sprintf("%s:%d", req.SessionKey, finalizeCount),
 			Payload: &eventbus.SessionCompletedPayload{
 				SessionKey:      req.SessionKey,
 				MessageCount:    len(history) + len(rs.pendingMsgs),
 				TokensUsed:      rs.totalUsage.PromptTokens + rs.totalUsage.CompletionTokens,
-				CompactionCount: l.sessions.GetCompactionCount(ctx, req.SessionKey),
+				CompactionCount: finalizeCount,
 			},
 		})
 	}
 
+	var lastUsage *providers.Usage
+	if rs.lastUsage.PromptTokens > 0 || rs.lastUsage.CompletionTokens > 0 || rs.lastUsage.TotalTokens > 0 {
+		lastUsage = &rs.lastUsage
+	}
+
 	return &RunResult{
 		Content:        rs.finalContent,
 		Thinking:       rs.finalThinking,
 		RunID:          req.RunID,
 		Iterations:     rs.iteration,
 		Usage:          &rs.totalUsage,
+		LastUsage:      lastUsage,
 		Media:          rs.mediaResults,
 		Deliverables:   rs.deliverables,
 		BlockReplies:   rs.blockReplies,
diff --git a/internal/agent/loop_history_sanitize.go b/internal/agent/loop_history_sanitize.go
index 516667f8..a55b2bf9 100644
--- a/internal/agent/loop_history_sanitize.go
+++ b/internal/agent/loop_history_sanitize.go
@@ -213,16 +213,30 @@ func hasPendingToolResultAhead(msgs []providers.Message, start int, idQueue map[
 	return false
 }
 
-func (l *Loop) maybeSummarize(ctx context.Context, sessionKey string) {
+// maybeSummarize truncates+summarizes session history when it grows large.
+//
+// midLoopCompacted signals that the final-request guard already had to compact
+// this session mid-loop. Because mid-loop compaction only mutates the run's
+// message buffer (never the session store), it is thrown away every turn —
+// causing an unbounded re-compaction loop AND stalling the cumulative compaction
+// count episodic depends on. When set, we lower the trigger threshold to a
+// unit-aligned "pressure threshold" so the compaction gets PERSISTED here.
+func (l *Loop) maybeSummarize(ctx context.Context, sessionKey string, midLoopCompacted bool) {
 	history := l.sessions.GetHistory(ctx, sessionKey)
 
 	// Use calibrated token estimation, adjusted for overhead.
 	// lastPromptTokens includes everything (system prompt, tools, context files, history).
 	// We subtract estimated overhead so the threshold comparison is history-only.
 	lastPT, lastMC := l.sessions.GetLastPromptTokens(ctx, sessionKey)
-	overheadEstimate := l.estimateOverhead(history, lastPT, lastMC)
-	adjustedLastPT := max(lastPT-overheadEstimate, 0)
-	tokenEstimate := EstimateTokensWithCalibration(history, adjustedLastPT, lastMC)
+	calibrationPT, calibrationMC := lastPT, lastMC
+	calibrationInvalid := l.contextWindow > 0 && lastPT > l.contextWindow
+	if calibrationInvalid {
+		calibrationPT = 0
+		calibrationMC = 0
+	}
+	overheadEstimate := l.estimateOverhead(history, calibrationPT, calibrationMC)
+	adjustedLastPT := max(calibrationPT-overheadEstimate, 0)
+	tokenEstimate := EstimateTokensWithCalibration(history, adjustedLastPT, calibrationMC)
 
 	// Resolve compaction threshold from config: token-only (no message count guard).
 	// Industry standard — Claude Code, Anthropic API, LangChain all use token-based thresholds.
@@ -231,9 +245,28 @@ func (l *Loop) maybeSummarize(ctx context.Context, sessionKey string) {
 		historyShare = l.compactionCfg.MaxHistoryShare
 	}
 
+	// Baseline (floor) threshold: history-only, MaxHistoryShare. Used when there was
+	// no mid-loop pressure this run — keeps normal sessions from over-compacting.
 	threshold := int(float64(l.contextWindow) * historyShare)
-	if tokenEstimate <= threshold {
-		l.logCompactionDecision(sessionKey, "skip", "under_threshold", tokenEstimate, threshold, historyShare, lastPT, lastMC, adjustedLastPT, overheadEstimate)
+	effectiveThreshold := threshold
+	if midLoopCompacted {
+		// Pressure threshold: align the unit + constants with the final-request guard by
+		// reusing compactionInputCap() (min(cw-maxTokens, cw*MaxRequestShare-maxTokens)),
+		// then subtract the fixed overhead estimate to compare against history-only
+		// tokenEstimate. The guard reads MaxRequestShare while this path historically read
+		// MaxHistoryShare — a DIFFERENT config field — so we must NOT rebuild the formula
+		// from historyShare or the two would diverge under custom config.
+		pressureThreshold := max(l.compactionInputCap()-overheadEstimate, 0)
+		// Defensive floor: a pathological config (maxTokens >= cw*MaxRequestShare) could
+		// drive compactionInputCap() toward 0, making pressureThreshold≈0 and forcing a
+		// summarize on every mid-loop turn. Never drop below half the baseline threshold.
+		if minFloor := threshold / 2; pressureThreshold < minFloor {
+			pressureThreshold = minFloor
+		}
+		effectiveThreshold = pressureThreshold
+	}
+	if tokenEstimate <= effectiveThreshold {
+		l.logCompactionDecision(sessionKey, "skip", "under_threshold", tokenEstimate, effectiveThreshold, historyShare, lastPT, lastMC, adjustedLastPT, overheadEstimate, calibrationInvalid)
 		return
 	}
 
@@ -243,12 +276,12 @@ func (l *Loop) maybeSummarize(ctx context.Context, sessionKey string) {
 	muI, _ := l.summarizeMu.LoadOrStore(sessionKey, &sync.Mutex{})
 	sessionMu := muI.(*sync.Mutex)
 	if !sessionMu.TryLock() {
-		l.logCompactionDecision(sessionKey, "skip", "already_in_progress", tokenEstimate, threshold, historyShare, lastPT, lastMC, adjustedLastPT, overheadEstimate)
+		l.logCompactionDecision(sessionKey, "skip", "already_in_progress", tokenEstimate, effectiveThreshold, historyShare, lastPT, lastMC, adjustedLastPT, overheadEstimate, calibrationInvalid)
 		slog.Debug("summarization already in progress, skipping", "session", sessionKey)
 		return
 	}
 
-	l.logCompactionDecision(sessionKey, "trigger", "", tokenEstimate, threshold, historyShare, lastPT, lastMC, adjustedLastPT, overheadEstimate)
+	l.logCompactionDecision(sessionKey, "trigger", "", tokenEstimate, effectiveThreshold, historyShare, lastPT, lastMC, adjustedLastPT, overheadEstimate, calibrationInvalid)
 
 	// Memory flush runs synchronously INSIDE the guard
 	// (so concurrent runs don't both trigger flush for the same compaction cycle).
@@ -282,42 +315,49 @@ func (l *Loop) maybeSummarize(ctx context.Context, sessionKey string) {
 		summary := l.sessions.GetSummary(sctx, sessionKey)
 		toSummarize := history[:len(history)-keepLast]
 
-		var sb strings.Builder
+		// Resolve the same per-agent request budget the mid-loop compaction path
+		// uses so no single summarization request can exceed the window. The old
+		// path concatenated the entire history into one prompt, which could blow
+		// the hard ceiling on large sessions; chunk + map-reduce keeps every
+		// request within cap.
+		inputCap := l.compactionInputCap()
+		if inputCap <= 0 {
+			slog.Warn("summarization failed", "session", sessionKey, "error", "context_window_unresolved")
+			return
+		}
+
 		var mediaKinds []string
 		for _, m := range toSummarize {
-			if m.Role == "user" {
-				sb.WriteString(fmt.Sprintf("user: %s\n", m.Content))
-			} else if m.Role == "assistant" {
-				sb.WriteString(fmt.Sprintf("assistant: %s\n", SanitizeAssistantContent(m.Content)))
-			}
 			for _, ref := range m.MediaRefs {
 				mediaKinds = append(mediaKinds, ref.Kind)
 			}
 		}
 
-		var prompt strings.Builder
-		prompt.WriteString(compactionSummaryPrompt)
+		// Build cap-respecting units, prepending any existing summary and a media
+		// note as their own leading units so the packer can split them if needed.
+		var leading []string
+		if summary != "" {
+			leading = append(leading, "Existing context: "+summary+"\n\n")
+		}
 		if len(mediaKinds) > 0 {
-			// Deduplicate and count media types for a compact note.
 			counts := make(map[string]int)
 			for _, k := range mediaKinds {
 				counts[k]++
 			}
-			prompt.WriteString("Note: user shared media files (")
+			var note strings.Builder
+			note.WriteString("Note: user shared media files (")
 			first := true
 			for k, n := range counts {
 				if !first {
-					prompt.WriteString(", ")
+					note.WriteString(", ")
 				}
-				prompt.WriteString(fmt.Sprintf("%d %s(s)", n, k))
+				note.WriteString(fmt.Sprintf("%d %s(s)", n, k))
 				first = false
 			}
-			prompt.WriteString(") which are no longer in context. Mention briefly if relevant.\n\n")
+			note.WriteString(") which are no longer in context. Mention briefly if relevant.\n\n")
+			leading = append(leading, note.String())
 		}
-		if summary != "" {
-			prompt.WriteString("Existing context: " + summary + "\n\n")
-		}
-		prompt.WriteString(sb.String())
+		units := append(leading, buildCompactionUnits(toSummarize)...)
 
 		inTokens := l.estimateSummaryInputTokens(toSummarize)
 		slog.Info("compact_budget",
@@ -327,22 +367,19 @@ func (l *Loop) maybeSummarize(ctx context.Context, sessionKey string) {
 			"in_tokens", inTokens,
 			"out_tokens", dynamicSummaryMax(inTokens),
 			"context_window", l.contextWindow,
+			"input_cap_tokens", inputCap,
 			"threshold", threshold,
 			"token_estimate", tokenEstimate,
 			"max_history_share", historyShare,
 			"reserve_tokens_floor", l.resolveReserveTokens(),
 			"timeout_seconds", int(timeout/time.Second),
 		)
-		chatReq := providers.ChatRequest{
-			Messages: []providers.Message{{Role: "user", Content: prompt.String()}},
-			Model:    l.model,
-			Options:  map[string]any{"max_tokens": dynamicSummaryMax(inTokens), "temperature": 0.3},
-		}
-		resp, err := l.callInternalLLMWithUsage(sctx, chatReq, "session-summarization")
+		summaryContent, _, err := l.summarizeCompactionUnits(sctx, units, inputCap, 1)
 		if err != nil {
 			slog.Warn("summarization failed", "session", sessionKey, "error", err)
 			return
 		}
+		resp := &providers.ChatResponse{Content: summaryContent}
 
 		// Collect MediaRefs from messages about to be truncated (keep up to 30 most recent).
 		const maxPreservedMediaRefs = 30
@@ -381,7 +418,7 @@ func (l *Loop) maybeSummarize(ctx context.Context, sessionKey string) {
 	}()
 }
 
-func (l *Loop) logCompactionDecision(sessionKey, decision, skipReason string, tokenEstimate, threshold int, historyShare float64, lastPromptTokens, lastMessageCount, adjustedLastPromptTokens, overheadEstimate int) {
+func (l *Loop) logCompactionDecision(sessionKey, decision, skipReason string, tokenEstimate, threshold int, historyShare float64, lastPromptTokens, lastMessageCount, adjustedLastPromptTokens, overheadEstimate int, calibrationInvalid bool) {
 	args := []any{
 		"path", "post-turn",
 		"agent", l.id,
@@ -396,6 +433,10 @@ func (l *Loop) logCompactionDecision(sessionKey, decision, skipReason string, to
 		"last_message_count", lastMessageCount,
 		"adjusted_last_prompt_tokens", adjustedLastPromptTokens,
 		"overhead_estimate", overheadEstimate,
+		"calibration_invalid", calibrationInvalid,
+	}
+	if calibrationInvalid {
+		args = append(args, "invalid_last_prompt_tokens", lastPromptTokens)
 	}
 	if skipReason != "" {
 		args = append(args, "skip_reason", skipReason)
diff --git a/internal/agent/loop_history_sanitize_max_tokens_test.go b/internal/agent/loop_history_sanitize_max_tokens_test.go
index 79c23f36..3a19e0f8 100644
--- a/internal/agent/loop_history_sanitize_max_tokens_test.go
+++ b/internal/agent/loop_history_sanitize_max_tokens_test.go
@@ -5,6 +5,7 @@ import (
 	"context"
 	"log/slog"
 	"strings"
+	"sync"
 	"testing"
 	"time"
 
@@ -21,6 +22,21 @@ type nopSessionStore struct {
 	history          []providers.Message
 	lastPromptTokens int
 	lastMsgCount     int
+	inputTokens      int64
+	outputTokens     int64
+	setLastTokens    int
+	setLastMsgCount  int
+
+	// Configurable/recording fields for compaction-count and truncation tests.
+	// Guarded by mu because maybeSummarize mutates them from a background goroutine.
+	mu               sync.Mutex
+	summary          string // returned by GetSummary
+	compactionCount  int    // returned by GetCompactionCount
+	incrementCalls   int    // counts IncrementCompaction invocations
+	truncateCalls    int    // counts TruncateHistory invocations
+	truncateKeepLast int    // last keepLast passed to TruncateHistory
+	setSummaryCalls  int    // counts SetSummary invocations
+	lastSetSummary   string // last summary passed to SetSummary
 }
 
 // SessionCoreStore methods
@@ -30,24 +46,61 @@ func (n *nopSessionStore) GetOrCreate(_ context.Context, _ string) *store.Sessio
 func (n *nopSessionStore) Get(_ context.Context, _ string) *store.SessionData          { return nil }
 func (n *nopSessionStore) AddMessage(_ context.Context, _ string, _ providers.Message) {}
 func (n *nopSessionStore) GetHistory(_ context.Context, _ string) []providers.Message {
+	n.mu.Lock()
+	defer n.mu.Unlock()
 	return n.history
 }
-func (n *nopSessionStore) GetSummary(_ context.Context, _ string) string                   { return "" }
-func (n *nopSessionStore) SetSummary(_ context.Context, _, _ string)                       {}
+func (n *nopSessionStore) GetSummary(_ context.Context, _ string) string {
+	n.mu.Lock()
+	defer n.mu.Unlock()
+	return n.summary
+}
+func (n *nopSessionStore) SetSummary(_ context.Context, _, s string) {
+	n.mu.Lock()
+	defer n.mu.Unlock()
+	n.setSummaryCalls++
+	n.lastSetSummary = s
+}
 func (n *nopSessionStore) GetLabel(_ context.Context, _ string) string                     { return "" }
 func (n *nopSessionStore) SetLabel(_ context.Context, _, _ string)                         {}
 func (n *nopSessionStore) SetAgentInfo(_ context.Context, _ string, _ uuid.UUID, _ string) {}
-func (n *nopSessionStore) TruncateHistory(_ context.Context, _ string, _ int)              {}
-func (n *nopSessionStore) SetHistory(_ context.Context, _ string, _ []providers.Message)   {}
+func (n *nopSessionStore) TruncateHistory(_ context.Context, _ string, keepLast int) {
+	n.mu.Lock()
+	defer n.mu.Unlock()
+	n.truncateCalls++
+	n.truncateKeepLast = keepLast
+	// Mirror real-store semantics: keep only the last keepLast messages so
+	// anti-loop tests observe an actually-shrunken history on the next turn.
+	if keepLast >= 0 && keepLast < len(n.history) {
+		n.history = n.history[len(n.history)-keepLast:]
+	}
+}
+func (n *nopSessionStore) SetHistory(_ context.Context, _ string, msgs []providers.Message) {
+	n.mu.Lock()
+	defer n.mu.Unlock()
+	n.history = msgs
+}
 func (n *nopSessionStore) Reset(_ context.Context, _ string)                               {}
 func (n *nopSessionStore) Delete(_ context.Context, _ string) error                        { return nil }
 func (n *nopSessionStore) Save(_ context.Context, _ string) error                          { return nil }
 
 // SessionMetadataStore methods
-func (n *nopSessionStore) UpdateMetadata(_ context.Context, _, _, _, _ string)           {}
-func (n *nopSessionStore) AccumulateTokens(_ context.Context, _ string, _, _ int64)      {}
-func (n *nopSessionStore) IncrementCompaction(_ context.Context, _ string)               {}
-func (n *nopSessionStore) GetCompactionCount(_ context.Context, _ string) int            { return 0 }
+func (n *nopSessionStore) UpdateMetadata(_ context.Context, _, _, _, _ string) {}
+func (n *nopSessionStore) AccumulateTokens(_ context.Context, _ string, input, output int64) {
+	n.inputTokens += input
+	n.outputTokens += output
+}
+func (n *nopSessionStore) IncrementCompaction(_ context.Context, _ string) {
+	n.mu.Lock()
+	defer n.mu.Unlock()
+	n.incrementCalls++
+	n.compactionCount++
+}
+func (n *nopSessionStore) GetCompactionCount(_ context.Context, _ string) int {
+	n.mu.Lock()
+	defer n.mu.Unlock()
+	return n.compactionCount
+}
 func (n *nopSessionStore) GetMemoryFlushCompactionCount(_ context.Context, _ string) int { return 0 }
 func (n *nopSessionStore) SetMemoryFlushDone(_ context.Context, _ string)                {}
 func (n *nopSessionStore) GetSessionMetadata(_ context.Context, _ string) map[string]string {
@@ -57,7 +110,12 @@ func (n *nopSessionStore) SetSessionMetadata(_ context.Context, _ string, _ map[
 func (n *nopSessionStore) SetSpawnInfo(_ context.Context, _, _ string, _ int)                  {}
 func (n *nopSessionStore) SetContextWindow(_ context.Context, _ string, _ int)                 {}
 func (n *nopSessionStore) GetContextWindow(_ context.Context, _ string) int                    { return 0 }
-func (n *nopSessionStore) SetLastPromptTokens(_ context.Context, _ string, _, _ int)           {}
+func (n *nopSessionStore) SetLastPromptTokens(_ context.Context, _ string, tokens, msgCount int) {
+	n.setLastTokens = tokens
+	n.setLastMsgCount = msgCount
+	n.lastPromptTokens = tokens
+	n.lastMsgCount = msgCount
+}
 func (n *nopSessionStore) GetLastPromptTokens(_ context.Context, _ string) (int, int) {
 	return n.lastPromptTokens, n.lastMsgCount
 }
@@ -74,6 +132,19 @@ func (n *nopSessionStore) LastUsedChannel(_ context.Context, _ string) (string,
 	return "", ""
 }
 
+// Thread-safe accessors for recording fields (maybeSummarize mutates them from a
+// background goroutine, so tests must not read the fields directly under -race).
+func (n *nopSessionStore) truncateCount() int {
+	n.mu.Lock()
+	defer n.mu.Unlock()
+	return n.truncateCalls
+}
+func (n *nopSessionStore) incrementCount() int {
+	n.mu.Lock()
+	defer n.mu.Unlock()
+	return n.incrementCalls
+}
+
 // signallingProvider wraps capturingProvider and signals a channel when Chat is called.
 type signallingProvider struct {
 	capturingProvider
@@ -94,11 +165,17 @@ func (s *signallingProvider) Chat(ctx context.Context, req providers.ChatRequest
 func TestMaybeSummarize_MaxTokensDynamic(t *testing.T) {
 	const contextWindow = 10000
 
-	// Build history large enough to exceed the compaction threshold.
+	// Agent-only budget: the calling agent reserves a FIXED maxTokens from the
+	// window, so compactionInputCap() = min(window-maxTokens, share*window-maxTokens).
+	// With window=10000, maxTokens=1024 → inputCap = min(8976, 7476) = 7476.
+	const maxTokens = 1024
+
+	// Build history large enough to exceed the compaction threshold while still
+	// packing the to-summarize slice into a single chunk under the input cap.
 	// threshold = contextWindow * DefaultHistoryShare = 10000 * 0.85 = 8500.
-	// EstimateTokens uses ~4 chars/token; 9000 tokens * 4 = 36000 chars of content.
-	// Use 5 user-assistant pairs each carrying ~9000 chars so EstimateTokens > threshold.
-	longContent := makeLongString(9000)
+	// estimateMessageTokens ≈ runes/3; 10 msgs × 3000 chars → ~10000 tokens > 8500.
+	// The 6 to-summarize messages pack into one ~6520-token chunk (< 7476 cap).
+	longContent := makeLongString(3000)
 	history := make([]providers.Message, 10)
 	for i := range history {
 		if i%2 == 0 {
@@ -124,6 +201,7 @@ func TestMaybeSummarize_MaxTokensDynamic(t *testing.T) {
 		provider:      sp,
 		model:         "claude-3-5-sonnet",
 		contextWindow: contextWindow,
+		maxTokens:     maxTokens,
 		sessions:      sessions,
 		// hasMemory = false → shouldRunMemoryFlush returns false (skip memory flush)
 		hasMemory: false,
@@ -132,7 +210,7 @@ func TestMaybeSummarize_MaxTokensDynamic(t *testing.T) {
 		// tokenCounter nil → estimateSummaryInputTokens uses rune/3 fallback
 	}
 
-	loop.maybeSummarize(context.Background(), "test-session-key")
+	loop.maybeSummarize(context.Background(), "test-session-key", false)
 
 	// Wait for background goroutine to call provider.Chat (up to 5s).
 	select {
@@ -151,7 +229,7 @@ func TestMaybeSummarize_MaxTokensDynamic(t *testing.T) {
 		t.Fatal("Options[\"max_tokens\"] not set in ChatRequest from maybeSummarize")
 	}
 
-	maxTokens, ok := maxTokensRaw.(int)
+	gotMaxTokens, ok := maxTokensRaw.(int)
 	if !ok {
 		t.Fatalf("Options[\"max_tokens\"] type = %T, want int", maxTokensRaw)
 	}
@@ -162,8 +240,8 @@ func TestMaybeSummarize_MaxTokensDynamic(t *testing.T) {
 	toSummarize := history[:len(history)-4]
 	expectedIn := loop.estimateSummaryInputTokens(toSummarize)
 	wantMax := dynamicSummaryMax(expectedIn)
-	if maxTokens != wantMax {
-		t.Errorf("max_tokens = %d, want %d (dynamicSummaryMax(%d))", maxTokens, wantMax, expectedIn)
+	if gotMaxTokens != wantMax {
+		t.Errorf("max_tokens = %d, want %d (dynamicSummaryMax(%d))", gotMaxTokens, wantMax, expectedIn)
 	}
 }
 
@@ -186,7 +264,7 @@ func TestMaybeSummarize_LogsSkipDecisionUnderThreshold(t *testing.T) {
 	}
 
 	logs := captureSlog(t, func() {
-		loop.maybeSummarize(context.Background(), "test-session-key")
+		loop.maybeSummarize(context.Background(), "test-session-key", false)
 	})
 
 	assertLogContains(t, logs,
@@ -200,10 +278,49 @@ func TestMaybeSummarize_LogsSkipDecisionUnderThreshold(t *testing.T) {
 	)
 }
 
+func TestMaybeSummarize_IgnoresInvalidLastPromptCalibration(t *testing.T) {
+	provider := &capturingProvider{response: "unused"}
+	sessions := &nopSessionStore{
+		history: []providers.Message{
+			{Role: "user", Content: "short request"},
+			{Role: "assistant", Content: "short response"},
+		},
+		lastPromptTokens: 264722,
+		lastMsgCount:     28,
+	}
+	loop := &Loop{
+		id:            "test-agent",
+		provider:      provider,
+		model:         "claude-3-5-sonnet",
+		contextWindow: 200000,
+		sessions:      sessions,
+		hasMemory:     false,
+	}
+
+	logs := captureSlog(t, func() {
+		loop.maybeSummarize(context.Background(), "test-session-key", false)
+	})
+
+	if len(provider.captured) != 0 {
+		t.Fatalf("provider.Chat called %d times, want 0 for invalid calibration under fallback threshold", len(provider.captured))
+	}
+	assertLogContains(t, logs,
+		"compaction_decision",
+		`"decision":"skip"`,
+		`"skip_reason":"under_threshold"`,
+		`"last_prompt_tokens":264722`,
+		`"calibration_invalid":true`,
+		`"invalid_last_prompt_tokens":264722`,
+	)
+}
+
 func TestMaybeSummarize_LogsTriggerDecisionOverThreshold(t *testing.T) {
 	const contextWindow = 10000
+	// Fixed agent reserve so compactionInputCap() leaves room to pack the
+	// to-summarize slice into one chunk (see TestMaybeSummarize_MaxTokensDynamic).
+	const maxTokens = 1024
 
-	longContent := makeLongString(9000)
+	longContent := makeLongString(3000)
 	history := make([]providers.Message, 10)
 	for i := range history {
 		if i%2 == 0 {
@@ -228,12 +345,13 @@ func TestMaybeSummarize_LogsTriggerDecisionOverThreshold(t *testing.T) {
 		provider:      provider,
 		model:         "claude-3-5-sonnet",
 		contextWindow: contextWindow,
+		maxTokens:     maxTokens,
 		sessions:      sessions,
 		hasMemory:     false,
 	}
 
 	logs := captureSlog(t, func() {
-		loop.maybeSummarize(context.Background(), "test-session-key")
+		loop.maybeSummarize(context.Background(), "test-session-key", false)
 
 		// Wait for the background summarize goroutine to reach the point where it
 		// calls provider.Chat (which happens strictly after the "compact_budget"
diff --git a/internal/agent/loop_maybe_summarize_pressure_test.go b/internal/agent/loop_maybe_summarize_pressure_test.go
new file mode 100644
index 00000000..b84b890d
--- /dev/null
+++ b/internal/agent/loop_maybe_summarize_pressure_test.go
@@ -0,0 +1,258 @@
+package agent
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/nextlevelbuilder/goclaw/internal/providers"
+)
+
+// Fixture math for these tests (contextWindow=200000, maxTokens=8192, nil cfg):
+//
+//	effectiveMaxTokens   = 8192
+//	compactionInputCap   = min(200000-8192, int(200000*0.85)-8192) = min(191808, 161808) = 161808
+//	baseline threshold   = int(200000*0.85)                        = 170000
+//	overhead (no calib)  = min(int(200000*0.2), 40000)             = 40000
+//	pressureThreshold    = max(161808-40000, 0)                    = 121808
+//	defensive floor      = 170000/2                                = 85000  (< 121808, so unused)
+//
+// Token estimate (no calibration) = sum(runes(content)/3) over all history messages.
+// Bands used below:
+//
+//	~100k tokens → below BOTH thresholds → skip even under mid-loop pressure
+//	~150k tokens → between pressure(121808) and baseline(170000) → persist ONLY under pressure
+const (
+	pressureContextWindow = 200000
+	pressureMaxTokens     = 8192
+)
+
+// buildTokenHistory returns n alternating user/assistant messages whose combined
+// rune/3 token estimate is approximately targetTokens. Each message carries
+// targetTokens/n * 3 runes so EstimateTokens(history) ≈ targetTokens.
+func buildTokenHistory(n, targetTokens int) []providers.Message {
+	perMsgTokens := targetTokens / n
+	perMsgRunes := perMsgTokens * 3
+	content := makeLongString(perMsgRunes)
+	history := make([]providers.Message, n)
+	for i := range history {
+		if i%2 == 0 {
+			history[i] = providers.Message{Role: "user", Content: content}
+		} else {
+			history[i] = providers.Message{Role: "assistant", Content: content}
+		}
+	}
+	return history
+}
+
+// waitForCount polls get() until it reaches want or the deadline elapses.
+func waitForCount(t *testing.T, get func() int, want int) {
+	t.Helper()
+	deadline := time.Now().Add(5 * time.Second)
+	for time.Now().Before(deadline) {
+		if get() >= want {
+			return
+		}
+		time.Sleep(5 * time.Millisecond)
+	}
+	t.Fatalf("timed out waiting for count to reach %d, last=%d", want, get())
+}
+
+func newPressureLoop(sessions *nopSessionStore, provider providers.Provider) *Loop {
+	return &Loop{
+		id:            "test-agent",
+		provider:      provider,
+		model:         "claude-3-5-sonnet",
+		contextWindow: pressureContextWindow,
+		maxTokens:     pressureMaxTokens,
+		sessions:      sessions,
+		hasMemory:     false,
+		compactionCfg: nil,
+	}
+}
+
+// V1-B / V2 core: a run that compacted mid-loop lowers the threshold to
+// pressureThreshold (121808). History at ~150k tokens is BELOW the baseline
+// (170000) but ABOVE the pressure threshold → summarize must run and PERSIST
+// (TruncateHistory + IncrementCompaction each exactly once).
+func TestMaybeSummarize_MidLoopPressurePersists(t *testing.T) {
+	sessions := &nopSessionStore{
+		history: buildTokenHistory(20, 150000), // ~150k tokens
+	}
+	loop := newPressureLoop(sessions, &capturingProvider{response: "compaction summary"})
+
+	loop.maybeSummarize(context.Background(), "sess-1", true)
+
+	waitForCount(t, sessions.incrementCount, 1)
+
+	if got := sessions.incrementCount(); got != 1 {
+		t.Errorf("IncrementCompaction called %d times, want 1", got)
+	}
+	if got := sessions.truncateCount(); got != 1 {
+		t.Errorf("TruncateHistory called %d times, want 1", got)
+	}
+	sessions.mu.Lock()
+	keepLast := sessions.truncateKeepLast
+	setSummary := sessions.setSummaryCalls
+	sessions.mu.Unlock()
+	if keepLast != 4 {
+		t.Errorf("TruncateHistory keepLast = %d, want 4", keepLast)
+	}
+	if setSummary != 1 {
+		t.Errorf("SetSummary called %d times, want 1", setSummary)
+	}
+}
+
+// V2 no-over-compaction (baseline case): the SAME ~150k history without mid-loop
+// pressure must SKIP (150000 < 170000 baseline). No summarize, no persist.
+func TestMaybeSummarize_NonMidLoopSkipsUnderBaseline(t *testing.T) {
+	provider := &capturingProvider{response: "should not be called"}
+	sessions := &nopSessionStore{
+		history: buildTokenHistory(20, 150000), // ~150k tokens
+	}
+	loop := newPressureLoop(sessions, provider)
+
+	loop.maybeSummarize(context.Background(), "sess-1", false)
+
+	// Skip returns synchronously before spawning the goroutine; give any
+	// (erroneously spawned) goroutine a brief window to prove it didn't run.
+	time.Sleep(50 * time.Millisecond)
+
+	if got := len(provider.captured); got != 0 {
+		t.Errorf("provider.Chat called %d times, want 0 (under baseline, no pressure)", got)
+	}
+	if got := sessions.incrementCount(); got != 0 {
+		t.Errorf("IncrementCompaction called %d times, want 0", got)
+	}
+	if got := sessions.truncateCount(); got != 0 {
+		t.Errorf("TruncateHistory called %d times, want 0", got)
+	}
+}
+
+// V2 no-over-compaction (the KEY case that distinguishes "lower threshold" from
+// "skip threshold"): mid-loop pressure is set, but the real history is small
+// (~100k tokens, below pressureThreshold=121808). The mid-loop compaction was
+// driven by transient tool-result bloat, not history — so we must STILL SKIP and
+// NOT truncate the session. This proves we lowered the threshold rather than
+// bypassing it.
+func TestMaybeSummarize_MidLoopSkipsWhenHistorySmall(t *testing.T) {
+	provider := &capturingProvider{response: "should not be called"}
+	sessions := &nopSessionStore{
+		history: buildTokenHistory(20, 100000), // ~100k tokens < pressureThreshold
+	}
+	loop := newPressureLoop(sessions, provider)
+
+	loop.maybeSummarize(context.Background(), "sess-1", true)
+
+	time.Sleep(50 * time.Millisecond)
+
+	if got := len(provider.captured); got != 0 {
+		t.Errorf("provider.Chat called %d times, want 0 (history below pressure threshold)", got)
+	}
+	if got := sessions.incrementCount(); got != 0 {
+		t.Errorf("IncrementCompaction called %d times, want 0 (no over-compaction)", got)
+	}
+	if got := sessions.truncateCount(); got != 0 {
+		t.Errorf("TruncateHistory called %d times, want 0 (no over-compaction)", got)
+	}
+}
+
+// V2 threshold-sync boundary: with one fixed history between the pressure
+// threshold (121808) and the baseline (170000), the ONLY thing that flips the
+// decision is the mid-loop flag. Persist when true, skip when false — proving
+// the two thresholds bracket this history exactly as designed.
+func TestMaybeSummarize_ThresholdSyncBoundary(t *testing.T) {
+	history := buildTokenHistory(20, 150000) // between 121808 and 170000
+
+	// mid-loop = false → skip
+	skipProvider := &capturingProvider{response: "unused"}
+	skipSessions := &nopSessionStore{history: cloneMessages(history)}
+	newPressureLoop(skipSessions, skipProvider).maybeSummarize(context.Background(), "sess-1", false)
+	time.Sleep(50 * time.Millisecond)
+	if got := skipSessions.incrementCount(); got != 0 {
+		t.Errorf("non-mid-loop: IncrementCompaction = %d, want 0 (skip above pressure, below baseline)", got)
+	}
+
+	// mid-loop = true → persist
+	triggerSessions := &nopSessionStore{history: cloneMessages(history)}
+	newPressureLoop(triggerSessions, &capturingProvider{response: "compaction summary"}).
+		maybeSummarize(context.Background(), "sess-1", true)
+	waitForCount(t, triggerSessions.incrementCount, 1)
+	if got := triggerSessions.incrementCount(); got != 1 {
+		t.Errorf("mid-loop: IncrementCompaction = %d, want 1 (persist under pressure)", got)
+	}
+}
+
+// V2 anti-loop (characterization): turn 1 persists the mid-loop compaction,
+// shrinking the session history. Turn 2 loads the now-small history, so even
+// with mid-loop pressure still set it stays below the pressure threshold and
+// does NOT re-compact — the unbounded re-compaction loop is broken.
+func TestMaybeSummarize_AntiLoop_SecondTurnDoesNotRecompact(t *testing.T) {
+	sessions := &nopSessionStore{
+		history: buildTokenHistory(20, 150000),
+	}
+	loop := newPressureLoop(sessions, &capturingProvider{response: "compaction summary"})
+
+	// Turn 1: pressure present, history large → persist (truncate to keepLast=4).
+	loop.maybeSummarize(context.Background(), "sess-1", true)
+	waitForCount(t, sessions.incrementCount, 1)
+
+	sessions.mu.Lock()
+	remaining := len(sessions.history)
+	sessions.mu.Unlock()
+	if remaining > 4 {
+		t.Fatalf("after turn 1 persist, history len = %d, want <= 4 (keepLast)", remaining)
+	}
+
+	// Turn 2: history is now tiny (4 messages). Even with pressure set, the
+	// history-only estimate is far below pressureThreshold → skip.
+	loop.maybeSummarize(context.Background(), "sess-1", true)
+	time.Sleep(50 * time.Millisecond)
+
+	if got := sessions.incrementCount(); got != 1 {
+		t.Errorf("after turn 2, IncrementCompaction total = %d, want 1 (no re-compaction)", got)
+	}
+	if got := sessions.truncateCount(); got != 1 {
+		t.Errorf("after turn 2, TruncateHistory total = %d, want 1 (no re-compaction)", got)
+	}
+}
+
+// Media preservation regression: MediaRefs on messages about to be truncated
+// must be carried onto the first kept message so the agent doesn't lose track of
+// shared files across a pressure-driven compaction.
+func TestMaybeSummarize_MidLoopPreservesMediaRefs(t *testing.T) {
+	history := buildTokenHistory(20, 150000)
+	// Attach a media ref to an early message (will be in the to-summarize slice).
+	history[0].MediaRefs = []providers.MediaRef{
+		{ID: "img-1", MimeType: "image/png", Kind: "image", Path: "/tmp/img-1.png"},
+	}
+	sessions := &nopSessionStore{history: history}
+	loop := newPressureLoop(sessions, &capturingProvider{response: "compaction summary"})
+
+	loop.maybeSummarize(context.Background(), "sess-1", true)
+	waitForCount(t, sessions.incrementCount, 1)
+
+	sessions.mu.Lock()
+	defer sessions.mu.Unlock()
+	if len(sessions.history) == 0 {
+		t.Fatal("history empty after truncation")
+	}
+	var found bool
+	for _, ref := range sessions.history[0].MediaRefs {
+		if ref.ID == "img-1" {
+			found = true
+			break
+		}
+	}
+	if !found {
+		t.Errorf("preserved media ref img-1 not found on first kept message; refs=%+v", sessions.history[0].MediaRefs)
+	}
+}
+
+// cloneMessages returns a shallow copy of a message slice so two Loops don't
+// share the same backing array (TruncateHistory mutates it in the mock).
+func cloneMessages(msgs []providers.Message) []providers.Message {
+	out := make([]providers.Message, len(msgs))
+	copy(out, msgs)
+	return out
+}
diff --git a/internal/agent/loop_pipeline_adapter.go b/internal/agent/loop_pipeline_adapter.go
index 61e07a42..24957378 100644
--- a/internal/agent/loop_pipeline_adapter.go
+++ b/internal/agent/loop_pipeline_adapter.go
@@ -2,6 +2,7 @@ package agent
 
 import (
 	"context"
+	"fmt"
 
 	"github.com/nextlevelbuilder/goclaw/internal/config"
 	"github.com/nextlevelbuilder/goclaw/internal/eventbus"
@@ -18,8 +19,10 @@ func (l *Loop) runViaPipeline(ctx context.Context, req RunRequest) (*RunResult,
 	input := convertRunInput(&req)
 	// Bridge runState shares loop detection state between pipeline and agent.
 	bridgeRS := &runState{}
-	deps := l.buildPipelineDeps(&req, bridgeRS)
 
+	// Resolve the effective model + provider BEFORE building deps so the pre-call
+	// budget estimate reserves reasoning output for the model that will actually
+	// run (a ModelOverride can change the reasoning capability, hence the bump).
 	model := l.model
 	if req.ModelOverride != "" {
 		model = req.ModelOverride
@@ -33,6 +36,8 @@ func (l *Loop) runViaPipeline(ctx context.Context, req RunRequest) (*RunResult,
 		}
 	}
 
+	deps := l.buildPipelineDeps(&req, bridgeRS)
+
 	p := pipeline.NewDefaultPipeline(deps)
 	state := pipeline.NewRunState(input, nil, model, provider)
 
@@ -44,6 +49,9 @@ func (l *Loop) runViaPipeline(ctx context.Context, req RunRequest) (*RunResult,
 }
 
 // buildPipelineDeps maps Loop fields + methods to PipelineDeps callbacks.
+// effProvider/effModel are the resolved provider+model for THIS run (after any
+// ModelOverride/ProviderOverride) so reasoning-effort resolution matches the
+// request the pipeline will actually send.
 func (l *Loop) buildPipelineDeps(req *RunRequest, bridgeRS *runState) pipeline.PipelineDeps {
 	maxIter := l.maxIterations
 	if req.MaxIterations > 0 && req.MaxIterations < maxIter {
@@ -69,9 +77,10 @@ func (l *Loop) buildPipelineDeps(req *RunRequest, bridgeRS *runState) pipeline.P
 	}
 
 	return pipeline.PipelineDeps{
-		TokenCounter: tokencount.NewTiktokenCounter(),
-		EventBus:     l.domainBus,
-		Hooks:        l.hookDispatcher,
+		TokenCounter:  tokencount.NewTiktokenCounter(),
+		BudgetCounter: l.budgetCounter,
+		EventBus:      l.domainBus,
+		Hooks:         l.hookDispatcher,
 		Config: pipeline.PipelineConfig{
 			MaxIterations:      maxIter,
 			MaxToolCalls:       l.maxToolCalls,
@@ -82,19 +91,7 @@ func (l *Loop) buildPipelineDeps(req *RunRequest, bridgeRS *runState) pipeline.P
 			Compaction:         l.compactionCfg,
 			// V3 memory/retrieval flags removed — always true at runtime.
 		},
-		// Resolve per-model context window once per run. Falls back to
-		// Config.ContextWindow when registry/model is unknown (existing
-		// behaviour unchanged for tests and lite edition).
-		ResolveContextWindow: func(provider, model string) int {
-			if l.modelRegistry == nil || model == "" {
-				return 0
-			}
-			spec := l.modelRegistry.Resolve(provider, model)
-			if spec == nil {
-				return 0
-			}
-			return spec.ContextWindow
-		},
+		ResolveContextWindow: l.resolveEffectiveContextWindow,
 		EmitEvent: func(event any) {
 			if ae, ok := event.(AgentEvent); ok {
 				l.emit(ae)
@@ -184,30 +181,10 @@ func (l *Loop) buildPipelineDeps(req *RunRequest, bridgeRS *runState) pipeline.P
 		StripMessageDirectives: StripMessageDirectives,
 		DeduplicateMediaSuffix: deduplicateMediaSuffix,
 		IsSilentReply:          IsSilentReply,
-		EmitSessionCompleted: func(ctx context.Context, sessionKey string, msgCount, tokensUsed, compactionCount int) {
-			if l.domainBus != nil {
-				// Include existing session summary (from previous compaction cycles).
-				// Current cycle's compaction runs async so its summary isn't ready yet,
-				// but previous summaries are available and useful for episodic creation.
-				var summary string
-				if compactionCount > 0 {
-					summary = l.sessions.GetSummary(ctx, sessionKey)
-				}
-				l.domainBus.Publish(eventbus.DomainEvent{
-					Type:     eventbus.EventSessionCompleted,
-					TenantID: l.tenantID.String(),
-					AgentID:  l.agentUUID.String(),
-					UserID:   req.UserID,
-					SourceID: sessionKey,
-					Payload: &eventbus.SessionCompletedPayload{
-						SessionKey:      sessionKey,
-						MessageCount:    msgCount,
-						TokensUsed:      tokensUsed,
-						CompactionCount: compactionCount,
-						Summary:         summary,
-					},
-				})
-			}
+		EmitSessionCompleted: func(ctx context.Context, sessionKey string, msgCount, tokensUsed, _ int) {
+			// The per-run count (5th arg) is intentionally ignored — emitSessionCompleted
+			// reads the CUMULATIVE session count itself (Bug A). See method doc.
+			l.emitSessionCompleted(ctx, sessionKey, req.UserID, msgCount, tokensUsed)
 		},
 		UpdateMetadata:   cb.updateMetadata,
 		BootstrapCleanup: cb.bootstrapCleanup,
@@ -215,6 +192,51 @@ func (l *Loop) buildPipelineDeps(req *RunRequest, bridgeRS *runState) pipeline.P
 	}
 }
 
+// emitSessionCompleted publishes the session.completed domain event that drives
+// the consolidation pipeline (episodic → semantic → dreaming). No-op when no bus.
+//
+// Bug A: it reads the CUMULATIVE session compaction count via GetCompactionCount
+// (matching the legacy v2 emit path) rather than the per-run counter the pipeline
+// tracks — the per-run counter resets to 0 each run, which pinned source_id at
+// ":0" and made the episodic worker skip every cycle after the first.
+//
+// Bug C: SourceID embeds that count ("<sessionKey>:<count>") so the eventbus dedup
+// key (Type+":"+SourceID, 5m TTL) advances per compaction cycle instead of
+// swallowing every rapid same-session turn. Safe for the worker, which builds its
+// own idempotency key from payload.SessionKey+payload.CompactionCount and never
+// parses SourceID.
+func (l *Loop) emitSessionCompleted(ctx context.Context, sessionKey, userID string, msgCount, tokensUsed int) {
+	if l.domainBus == nil {
+		return
+	}
+	count := l.sessions.GetCompactionCount(ctx, sessionKey)
+	// Attach the existing session summary (from a PREVIOUS compaction cycle) when
+	// one exists. The current cycle's summary is produced asynchronously and isn't
+	// ready yet, but a prior summary spares the worker an LLM re-summarize call.
+	var summary string
+	if count > 0 {
+		summary = l.sessions.GetSummary(ctx, sessionKey)
+	}
+	l.domainBus.Publish(eventbus.DomainEvent{
+		Type:     eventbus.EventSessionCompleted,
+		TenantID: l.tenantID.String(),
+		AgentID:  l.agentUUID.String(),
+		UserID:   userID,
+		SourceID: fmt.Sprintf("%s:%d", sessionKey, count),
+		Payload: &eventbus.SessionCompletedPayload{
+			SessionKey:      sessionKey,
+			MessageCount:    msgCount,
+			TokensUsed:      tokensUsed,
+			CompactionCount: count,
+			Summary:         summary,
+		},
+	})
+}
+
+func (l *Loop) resolveEffectiveContextWindow() int {
+	return l.contextWindow
+}
+
 // convertRunInput converts agent.RunRequest to pipeline.RunInput.
 func convertRunInput(req *RunRequest) *pipeline.RunInput {
 	return &pipeline.RunInput{
@@ -260,6 +282,11 @@ func convertRunResult(pr *pipeline.RunResult) *RunResult {
 	if pr == nil {
 		return nil
 	}
+	var lastUsage *providers.Usage
+	if pr.LastUsage.PromptTokens > 0 || pr.LastUsage.CompletionTokens > 0 || pr.LastUsage.TotalTokens > 0 {
+		lu := pr.LastUsage
+		lastUsage = &lu
+	}
 	media := make([]MediaResult, len(pr.MediaResults))
 	for i, m := range pr.MediaResults {
 		media[i] = MediaResult{
@@ -276,6 +303,7 @@ func convertRunResult(pr *pipeline.RunResult) *RunResult {
 		RunID:          pr.RunID,
 		Iterations:     pr.Iterations,
 		Usage:          &pr.TotalUsage,
+		LastUsage:      lastUsage,
 		Media:          media,
 		Deliverables:   pr.Deliverables,
 		BlockReplies:   pr.BlockReplies,
diff --git a/internal/agent/loop_pipeline_callbacks.go b/internal/agent/loop_pipeline_callbacks.go
index 3d26df6c..dd117613 100644
--- a/internal/agent/loop_pipeline_callbacks.go
+++ b/internal/agent/loop_pipeline_callbacks.go
@@ -95,7 +95,7 @@ type pipelineCallbackSet struct {
 	flushMessages      func(ctx context.Context, sessionKey string, msgs []providers.Message) error
 	updateMetadata     func(ctx context.Context, sessionKey string, usage, lastUsage providers.Usage, msgCount int) error
 	bootstrapCleanup   func(ctx context.Context, state *pipeline.RunState) error
-	maybeSummarize     func(ctx context.Context, sessionKey string)
+	maybeSummarize     func(ctx context.Context, sessionKey string, midLoopCompacted bool)
 }
 
 func (l *Loop) makeResolveWorkspace(req *RunRequest) func(ctx context.Context, input *pipeline.RunInput) (*workspace.WorkspaceContext, error) {
@@ -759,13 +759,25 @@ func (l *Loop) makeBootstrapCleanup() func(ctx context.Context, state *pipeline.
 }
 
 func (l *Loop) reserveLLMUsage(ctx context.Context, req *RunRequest, state *pipeline.RunState, chatReq providers.ChatRequest, attempt string) (*usagecaps.Reservation, error) {
-	if l.usageCaps == nil || state.Provider == nil {
-		return nil, nil
+	providerName := ""
+	if state.Provider != nil {
+		providerName = state.Provider.Name()
 	}
-	return l.reserveLLMUsageFor(ctx, req, state.Iteration, chatReq, attempt, state.Provider.Name(), state.Model)
+	// reserveLLMUsageFor runs the mandatory hard-ceiling guard before any
+	// reservation or transport, so the non-fallback path is guarded here even
+	// when usage caps are disabled (Lite runtime).
+	return l.reserveLLMUsageFor(ctx, req, state.Iteration, chatReq, attempt, providerName, state.Model)
 }
 
 func (l *Loop) reserveLLMUsageFor(ctx context.Context, req *RunRequest, iteration int, chatReq providers.ChatRequest, attempt, providerName, model string) (*usagecaps.Reservation, error) {
+	// Mandatory final hard-ceiling guard for the concrete request that is about
+	// to be sent, after all directive/retry/reasoning mutations. This is the
+	// shared pre-transport chokepoint for BOTH the fallback candidate path and
+	// the non-fallback path (via reserveLLMUsage), and for every retry attempt.
+	// It runs regardless of usage-cap configuration so the ceiling holds on Lite.
+	if guardErr := l.guardCompleteModelRequest(chatReq, providerName, model, attempt); guardErr != nil {
+		return nil, guardErr
+	}
 	if l.usageCaps == nil {
 		return nil, nil
 	}
diff --git a/internal/agent/loop_pipeline_callbacks_test.go b/internal/agent/loop_pipeline_callbacks_test.go
index 889c0f69..95a49e39 100644
--- a/internal/agent/loop_pipeline_callbacks_test.go
+++ b/internal/agent/loop_pipeline_callbacks_test.go
@@ -103,6 +103,59 @@ func TestSupportsPromptCacheParams(t *testing.T) {
 	}
 }
 
+func TestResolveEffectiveContextWindow_UsesAgentConfigOnly(t *testing.T) {
+	registry := &panicModelRegistry{}
+	loop := &Loop{contextWindow: 128_000, modelRegistry: registry}
+	if got := loop.resolveEffectiveContextWindow(); got != 128_000 {
+		t.Fatalf("resolveEffectiveContextWindow() = %d, want 128000", got)
+	}
+}
+
+type panicModelRegistry struct{}
+
+func (*panicModelRegistry) Resolve(_, _ string) *providers.ModelSpec {
+	panic("model registry must not participate in request budgeting")
+}
+
+func (*panicModelRegistry) Register(providers.ModelSpec) {
+	panic("model registry must not participate in request budgeting")
+}
+
+func (*panicModelRegistry) Catalog(string) []providers.ModelSpec {
+	panic("model registry must not participate in request budgeting")
+}
+
+func TestMakeUpdateMetadataStoresLastUsagePromptTokens(t *testing.T) {
+	sessions := &nopSessionStore{}
+	loop := &Loop{
+		model:    "test-model",
+		provider: finalThinkingStreamProvider{},
+		sessions: sessions,
+	}
+	req := &RunRequest{Channel: "telegram"}
+
+	update := loop.makeUpdateMetadata(req)
+	err := update(context.Background(), "sess-1",
+		providers.Usage{PromptTokens: 225000, CompletionTokens: 3000},
+		providers.Usage{PromptTokens: 70000, CompletionTokens: 100},
+		12,
+	)
+	if err != nil {
+		t.Fatalf("update metadata error: %v", err)
+	}
+	if sessions.inputTokens != 225000 || sessions.outputTokens != 3000 {
+		t.Fatalf("accumulated tokens = %d/%d, want total run 225000/3000", sessions.inputTokens, sessions.outputTokens)
+	}
+	// Upstream 503909d3 calibration: SetLastPromptTokens stores the final call's
+	// full context size (Usage.ContextTokens(), which adds cached segments back
+	// for Anthropic-style usage) PLUS the final completion — the reply joins
+	// history so it occupies the next request's prompt. No cache tokens here, so
+	// ContextTokens()=70000; +100 completion = 70100.
+	if sessions.setLastTokens != 70100 || sessions.setLastMsgCount != 12 {
+		t.Fatalf("last prompt calibration = %d/%d, want last request 70100/12", sessions.setLastTokens, sessions.setLastMsgCount)
+	}
+}
+
 // A Function-nil tool definition (e.g. the native image_generation sentinel,
 // providers.ToolDefinition{Type: "image_generation"}) must not panic the
 // mcp-def counter. Regression for the v3.14.0 nil-pointer crash.
diff --git a/internal/agent/loop_request_budget.go b/internal/agent/loop_request_budget.go
new file mode 100644
index 00000000..85cf0cd0
--- /dev/null
+++ b/internal/agent/loop_request_budget.go
@@ -0,0 +1,99 @@
+package agent
+
+import (
+	"fmt"
+	"log/slog"
+
+	"github.com/nextlevelbuilder/goclaw/internal/providers"
+)
+
+// RequestBudgetExceededError is returned before provider transport when the
+// COMPLETE final request (messages + tools + output reserve) exceeds the
+// receiving agent's configured context window. It is intentionally internal
+// to the agent loop: callers abort/reduce instead of falling through to model
+// fallback or sending an oversized payload.
+type RequestBudgetExceededError struct {
+	AgentID       string
+	Provider      string
+	Model         string
+	Attempt       string
+	InputTokens   int
+	OutputReserve int
+	ContextWindow int
+}
+
+func (e *RequestBudgetExceededError) Error() string {
+	return fmt.Sprintf(
+		"context budget exceeded: input=%d + output_reserve=%d > agent_window=%d (agent=%s provider=%s model=%s attempt=%s)",
+		e.InputTokens, e.OutputReserve, e.ContextWindow, e.AgentID, e.Provider, e.Model, e.Attempt,
+	)
+}
+
+// ContextBudgetExceeded marks this error as a request-level context-budget
+// overflow. Package-neutral consumers (pipeline.ThinkStage) detect it via an
+// interface check without importing the agent package, so they can re-enter
+// reduction (prune -> compact -> shrink) and rebuild before aborting.
+func (e *RequestBudgetExceededError) ContextBudgetExceeded() bool { return true }
+
+// guardCompleteModelRequest is the mandatory final boundary check for EVERY
+// model request emitted by an agent loop. Call it only after all messages,
+// tools, retry instructions, model overrides and options have been finalized,
+// and immediately before provider.Chat/ChatStream.
+//
+// Hard invariant:
+//
+//	completeInputTokens + outputReserveTokens <= agent.ContextWindow
+//
+// The configured agent context window and configured max_tokens are the only
+// budget authorities. Model and provider are diagnostic fields only.
+func (l *Loop) guardCompleteModelRequest(request providers.ChatRequest, providerName, model, attempt string) error {
+	// Bare Loop literals used by unrelated unit tests opt out; NewLoop always
+	// wires the fixed local budget counter.
+	if l.budgetCounter == nil {
+		return nil
+	}
+	contextWindow := l.resolveEffectiveContextWindow()
+	if contextWindow <= 0 {
+		return fmt.Errorf("context_window_unresolved: agent=%s provider=%s model=%s attempt=%s", l.id, providerName, model, attempt)
+	}
+
+	inputTokens, err := l.budgetCounter.CountRequest(request)
+	if err != nil {
+		return fmt.Errorf("count complete request: %w", err)
+	}
+	outputReserve := l.effectiveMaxTokens()
+
+	if inputTokens+outputReserve <= contextWindow {
+		slog.Debug("context_budget.guard",
+			"agent", l.id,
+			"provider", providerName,
+			"model", model,
+			"attempt", attempt,
+			"input_tokens", inputTokens,
+			"output_reserve_tokens", outputReserve,
+			"context_window", contextWindow,
+			"action", "allow")
+		return nil
+	}
+
+	slog.Info("context_budget.guard",
+		"agent", l.id,
+		"provider", providerName,
+		"model", model,
+		"attempt", attempt,
+		"input_tokens", inputTokens,
+		"output_reserve_tokens", outputReserve,
+		"context_window", contextWindow,
+		"action", "abort",
+		"reason", "context_budget_exceeded")
+
+	return &RequestBudgetExceededError{
+		AgentID:       l.id,
+		Provider:      providerName,
+		Model:         model,
+		Attempt:       attempt,
+		InputTokens:   inputTokens,
+		OutputReserve: outputReserve,
+		ContextWindow: contextWindow,
+	}
+}
diff --git a/internal/agent/loop_request_budget_test.go b/internal/agent/loop_request_budget_test.go
new file mode 100644
index 00000000..981f28ac
--- /dev/null
+++ b/internal/agent/loop_request_budget_test.go
@@ -0,0 +1,122 @@
+package agent
+
+import (
+	"errors"
+	"strings"
+	"testing"
+
+	"github.com/nextlevelbuilder/goclaw/internal/providers"
+	"github.com/nextlevelbuilder/goclaw/internal/tokencount"
+)
+
+func newBudgetTestLoop(window, maxTokens int) *Loop {
+	return &Loop{
+		id:            "budget-test",
+		contextWindow: window,
+		maxTokens:     maxTokens,
+		budgetCounter: tokencount.NewBudgetCounter(),
+	}
+}
+
+func budgetMessageAtLeast(t *testing.T, counter tokencount.BudgetCounter, target int) providers.Message {
+	t.Helper()
+	low, high := 1, target*8
+	for low < high {
+		mid := low + (high-low)/2
+		msg := providers.Message{Role: "user", Content: strings.Repeat("word ", mid)}
+		count, err := counter.CountMessages([]providers.Message{msg})
+		if err != nil {
+			t.Fatal(err)
+		}
+		if count < target {
+			low = mid + 1
+		} else {
+			high = mid
+		}
+	}
+	return providers.Message{Role: "user", Content: strings.Repeat("word ", low)}
+}
+
+func TestGuardCompleteModelRequest_AgentWindowOnly(t *testing.T) {
+	counter := tokencount.NewBudgetCounter()
+	msg := budgetMessageAtLeast(t, counter, 130_000)
+	req := providers.ChatRequest{Model: "model-a", Messages: []providers.Message{msg}}
+
+	loop128 := newBudgetTestLoop(128_000, 8_192)
+	err := loop128.guardCompleteModelRequest(req, "provider-a", "model-a", "initial")
+	if err == nil {
+		t.Fatal("128k agent: expected request to be blocked")
+	}
+	var budgetErr *RequestBudgetExceededError
+	if !errors.As(err, &budgetErr) {
+		t.Fatalf("expected RequestBudgetExceededError, got %T: %v", err, err)
+	}
+
+	loop200 := newBudgetTestLoop(200_000, 8_192)
+	if err := loop200.guardCompleteModelRequest(req, "provider-a", "model-a", "initial"); err != nil {
+		t.Fatalf("200k agent: expected request to fit, got %v", err)
+	}
+}
+
+func TestGuardCompleteModelRequest_ModelProviderIndependent(t *testing.T) {
+	loop := newBudgetTestLoop(128_000, 8_192)
+	base := providers.ChatRequest{
+		Model: "model-a",
+		Messages: []providers.Message{{
+			Role:     "assistant",
+			Content:  "same content",
+			Thinking: "same thinking",
+			ToolCalls: []providers.ToolCall{{
+				ID:        "call-1",
+				Name:      "read_file",
+				Arguments: map[string]any{"path": "/tmp/a"},
+				Metadata:  map[string]string{"thought_signature": "sig"},
+			}},
+		}},
+	}
+	other := base
+	other.Model = "totally-different-model"
+
+	first, err := loop.budgetCounter.CountRequest(base)
+	if err != nil {
+		t.Fatal(err)
+	}
+	second, err := loop.budgetCounter.CountRequest(other)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if first != second {
+		t.Fatalf("completeInput changed with model: %d != %d", first, second)
+	}
+	if errA, errB := loop.guardCompleteModelRequest(base, "provider-a", base.Model, "a"), loop.guardCompleteModelRequest(other, "provider-b", other.Model, "b"); (errA == nil) != (errB == nil) {
+		t.Fatalf("allow/abort changed with model/provider: %v vs %v", errA, errB)
+	}
+}
+
+func TestGuardCompleteModelRequest_MaxTokensChangesHardCapExactly(t *testing.T) {
+	counter := tokencount.NewBudgetCounter()
+	msg := budgetMessageAtLeast(t, counter, 7_500)
+	req := providers.ChatRequest{Messages: []providers.Message{msg}}
+	input, err := counter.CountRequest(req)
+	if err != nil {
+		t.Fatal(err)
+	}
+	window := input + 2_500
+
+	allow := newBudgetTestLoop(window, 2_500)
+	if err := allow.guardCompleteModelRequest(req, "p", "m", "allow"); err != nil {
+		t.Fatalf("input + 2500 should fit exactly: input=%d window=%d err=%v", input, window, err)
+	}
+	block := newBudgetTestLoop(window, 2_501)
+	if err := block.guardCompleteModelRequest(req, "p", "m", "block"); err == nil {
+		t.Fatalf("input + 2501 must exceed by one: input=%d window=%d", input, window)
+	}
+}
+
+func TestGuardCompleteModelRequest_FailsClosedOnUnresolvedAgentWindow(t *testing.T) {
+	loop := newBudgetTestLoop(0, 8_192)
+	req := providers.ChatRequest{Messages: []providers.Message{{Role: "user", Content: "hi"}}}
+	if err := loop.guardCompleteModelRequest(req, "provider", "model", "initial"); err == nil {
+		t.Fatal("expected wiring failure without configured agent window")
+	}
+}
diff --git a/internal/agent/loop_run.go b/internal/agent/loop_run.go
index fd573534..7837db29 100644
--- a/internal/agent/loop_run.go
+++ b/internal/agent/loop_run.go
@@ -206,7 +206,13 @@ func (l *Loop) Run(ctx context.Context, req RunRequest) (*RunResult, error) {
 			"iterations", result.Iterations,
 		}
 		if result.Usage != nil {
-			logAttrs = append(logAttrs, "total_tokens", result.Usage.TotalTokens)
+			logAttrs = append(logAttrs,
+				"total_tokens", result.Usage.TotalTokens,
+				"total_prompt_tokens", result.Usage.PromptTokens,
+			)
+		}
+		if result.LastUsage != nil {
+			logAttrs = append(logAttrs, "last_usage_prompt_tokens", result.LastUsage.PromptTokens)
 		}
 		slog.Info("v3.run.completed", logAttrs...)
 
diff --git a/internal/agent/loop_types.go b/internal/agent/loop_types.go
index 16a75f60..c2c43449 100644
--- a/internal/agent/loop_types.go
+++ b/internal/agent/loop_types.go
@@ -152,9 +152,11 @@ type Loop struct {
 	// Context pruning config (trim old tool results in-memory)
 	contextPruningCfg *config.ContextPruningConfig
 
-	// tokenCounter provides accurate per-model token counting for context pruning.
-	// Nil means the legacy char-based heuristic is used.
+	// tokenCounter is retained for legacy compaction/pruning estimates.
 	tokenCounter tokencount.TokenCounter
+	// budgetCounter is the fixed local, model-independent complete-input counter
+	// used by the request-budget invariant.
+	budgetCounter tokencount.BudgetCounter
 
 	// Sandbox info
 	sandboxEnabled         bool
@@ -480,6 +482,12 @@ func (l *Loop) effectiveMaxTokens() int {
 	return defaultMaxTokens
 }
 
+// ContextWindow returns the operator-configured agent context window.
+func (l *Loop) ContextWindow() int { return l.contextWindow }
+
+// MaxTokens returns the operator-configured effective agent max_tokens.
+func (l *Loop) MaxTokens() int { return l.effectiveMaxTokens() }
+
 // resolveReserveTokens returns the reserve token buffer from compaction config.
 // Issue 958: Wire ReserveTokensFloor to prevent context overflow before compaction.
 func (l *Loop) resolveReserveTokens() int {
@@ -559,6 +567,7 @@ func NewLoop(cfg LoopConfig) *Loop {
 		compactionCfg:          cfg.CompactionCfg,
 		contextPruningCfg:      cfg.ContextPruningCfg,
 		tokenCounter:           tokencount.NewTiktokenCounter(),
+		budgetCounter:          tokencount.NewBudgetCounter(),
 		sandboxEnabled:         cfg.SandboxEnabled,
 		sandboxContainerDir:    cfg.SandboxContainerDir,
 		sandboxWorkspaceAccess: cfg.SandboxWorkspaceAccess,
@@ -678,6 +687,7 @@ type RunResult struct {
 	RunID          string                `json:"runId"`
 	Iterations     int                   `json:"iterations"`
 	Usage          *providers.Usage      `json:"usage,omitempty"`
+	LastUsage      *providers.Usage      `json:"lastUsage,omitempty"`
 	Media          []MediaResult         `json:"media,omitempty"`          // media files from tool results (MEDIA: prefix)
 	Deliverables   []string              `json:"deliverables,omitempty"`   // actual content from tool outputs (for team task results)
 	BlockReplies   int                   `json:"blockReplies,omitempty"`   // number of block.reply events emitted
@@ -703,10 +713,12 @@ type MediaResult struct {
 // on *runState without passing 20+ individual variables.
 type runState struct {
 	// Loop control
-	loopDetector   toolLoopState
-	totalUsage     providers.Usage
-	iteration      int
-	totalToolCalls int
+	loopDetector      toolLoopState
+	totalUsage        providers.Usage
+	lastUsage         providers.Usage
+	lastUsageMsgCount int
+	iteration         int
+	totalToolCalls    int
 
 	// Output accumulators
 	finalContent   string
diff --git a/internal/agent/types.go b/internal/agent/types.go
index c46d99ac..9b2e579f 100644
--- a/internal/agent/types.go
+++ b/internal/agent/types.go
@@ -7,6 +7,7 @@ import (
 	"github.com/google/uuid"
 
 	"github.com/nextlevelbuilder/goclaw/internal/providers"
+	"github.com/nextlevelbuilder/goclaw/internal/store"
 )
 
 // Agent is the core abstraction for an AI agent execution loop.
@@ -21,3 +22,20 @@ type Agent interface {
 	ProviderName() string
 	Provider() providers.Provider
 }
+
+// BudgetedAgent exposes the configured agent-only request budget without adding
+// model/provider authority or expanding the broad Agent test interface.
+type BudgetedAgent interface {
+	ContextWindow() int
+	MaxTokens() int
+}
+
+// WithAgentBudget propagates an agent's configured budget to nested model calls.
+func WithAgentBudget(ctx context.Context, a Agent) context.Context {
+	budgeted, ok := a.(BudgetedAgent)
+	if !ok {
+		return ctx
+	}
+	ctx = store.WithAgentContextWindow(ctx, budgeted.ContextWindow())
+	return store.WithAgentMaxTokens(ctx, budgeted.MaxTokens())
+}
diff --git a/internal/agent/usage_caps_runtime.go b/internal/agent/usage_caps_runtime.go
index e883a9c3..91c39bf8 100644
--- a/internal/agent/usage_caps_runtime.go
+++ b/internal/agent/usage_caps_runtime.go
@@ -46,6 +46,12 @@ func (l *Loop) callInternalLLMWithUsage(ctx context.Context, chatReq providers.C
 	if fallbackProvider, ok := l.provider.(*providers.ModelFallbackProvider); ok {
 		before := func(callCtx context.Context, entry providers.FallbackCandidate, actualReq providers.ChatRequest) (providers.FallbackAfterCall, error) {
 			candidatePurpose := fmt.Sprintf("%s:%s:%s", purpose, entry.ProviderName, actualReq.Model)
+			// Mandatory hard-ceiling guard: internal calls (compaction, session
+			// summarization, memory flush) obey the SAME per-agent window as
+			// main-loop calls, per candidate, after all request mutations.
+			if guardErr := l.guardCompleteModelRequest(actualReq, entry.ProviderName, actualReq.Model, candidatePurpose); guardErr != nil {
+				return nil, guardErr
+			}
 			reservation, err := l.reserveInternalLLMUsageFor(callCtx, actualReq, candidatePurpose, entry.ProviderName, actualReq.Model)
 			if err != nil {
 				return nil, err
@@ -58,6 +64,18 @@ func (l *Loop) callInternalLLMWithUsage(ctx context.Context, chatReq providers.C
 		}
 		return fallbackProvider.ChatWithHook(ctx, chatReq, before)
 	}
+	providerName := ""
+	if l.provider != nil {
+		providerName = l.provider.Name()
+	}
+	callModel := chatReq.Model
+	if callModel == "" {
+		callModel = l.model
+	}
+	// Mandatory hard-ceiling guard for the non-fallback internal call path.
+	if guardErr := l.guardCompleteModelRequest(chatReq, providerName, callModel, purpose); guardErr != nil {
+		return nil, guardErr
+	}
 	reservation, reserveErr := l.reserveInternalLLMUsage(ctx, chatReq, purpose)
 	if reserveErr != nil {
 		return nil, reserveErr
diff --git a/internal/config/config.go b/internal/config/config.go
index c3c191a8..ce808be9 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -330,7 +330,8 @@ type AgentDefaults struct {
 // Matching TS agents.defaults.compaction.
 type CompactionConfig struct {
 	ReserveTokensFloor int                `json:"reserveTokensFloor,omitempty"` // min reserve tokens (default 20000)
-	MaxHistoryShare    float64            `json:"maxHistoryShare,omitempty"`    // max share of context for history (default 0.85)
+	MaxHistoryShare    float64            `json:"maxHistoryShare,omitempty"`    // max share of context for history-only post-turn compaction (default 0.85)
+	MaxRequestShare    float64            `json:"maxRequestShare,omitempty"`    // max share of context for the final request sent to the model (default 0.85)
 	KeepLastMessages   int                `json:"keepLastMessages,omitempty"`   // messages to keep after compaction (default 4)
 	TimeoutSeconds     int                `json:"timeoutSeconds,omitempty"`     // summarization timeout in seconds (default 120)
 	MemoryFlush        *MemoryFlushConfig `json:"memoryFlush,omitempty"`        // pre-compaction flush
diff --git a/internal/consolidation/agent_budget.go b/internal/consolidation/agent_budget.go
new file mode 100644
index 00000000..69a1e6d7
--- /dev/null
+++ b/internal/consolidation/agent_budget.go
@@ -0,0 +1,50 @@
+package consolidation
+
+import (
+	"context"
+	"log/slog"
+
+	"github.com/google/uuid"
+	"github.com/nextlevelbuilder/goclaw/internal/config"
+	"github.com/nextlevelbuilder/goclaw/internal/store"
+)
+
+// withAgentRequestBudget wires the calling agent's configured request
+// budget (context_window, max_tokens) into ctx so background LLM calls
+// (episodic summarization, dreaming synthesis) pass the agent-only preflight
+// guard instead of failing closed with an AgentBudgetWiringError.
+//
+// Background workers run off a session.completed / episodic.created event and
+// do not carry a live agent Loop, so the budget cannot come from
+// agent.WithAgentBudget. We load it straight from the agent row. If the store
+// is unavailable or the row cannot be read, we fall back to the operator
+// defaults rather than let a transient lookup miss silently kill memory
+// consolidation — the guard's job is to bound requests to the agent window,
+// and the defaults are the same window the agent would use unconfigured.
+func withAgentRequestBudget(ctx context.Context, agents store.AgentCRUDStore, agentID uuid.UUID, purpose string) context.Context {
+	contextWindow := config.DefaultContextWindow
+	maxTokens := config.DefaultMaxTokens
+
+	if agents != nil && agentID != uuid.Nil {
+		if ag, err := agents.GetByIDUnscoped(ctx, agentID); err != nil {
+			slog.Warn("consolidation: agent budget lookup failed, using defaults",
+				"purpose", purpose, "agent", agentID, "err", err,
+				"context_window", contextWindow, "max_tokens", maxTokens)
+		} else {
+			if ag.ContextWindow > 0 {
+				contextWindow = ag.ContextWindow
+			}
+			if ag.MaxTokens > 0 {
+				maxTokens = ag.MaxTokens
+			}
+		}
+	} else {
+		slog.Warn("consolidation: no agent store or agent id, using default budget",
+			"purpose", purpose, "agent", agentID,
+			"context_window", contextWindow, "max_tokens", maxTokens)
+	}
+
+	ctx = store.WithAgentContextWindow(ctx, contextWindow)
+	ctx = store.WithAgentMaxTokens(ctx, maxTokens)
+	return ctx
+}
diff --git a/internal/consolidation/agent_budget_test.go b/internal/consolidation/agent_budget_test.go
new file mode 100644
index 00000000..95bb8fda
--- /dev/null
+++ b/internal/consolidation/agent_budget_test.go
@@ -0,0 +1,82 @@
+package consolidation
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	"github.com/google/uuid"
+	"github.com/nextlevelbuilder/goclaw/internal/config"
+	"github.com/nextlevelbuilder/goclaw/internal/store"
+)
+
+// budgetAgentStore overrides only GetByIDUnscoped; the embedded nil interface
+// panics if any other method is called, which keeps the mock honest.
+type budgetAgentStore struct {
+	store.AgentCRUDStore
+	agent *store.AgentData
+	err   error
+}
+
+func (m *budgetAgentStore) GetByIDUnscoped(_ context.Context, _ uuid.UUID) (*store.AgentData, error) {
+	if m.err != nil {
+		return nil, m.err
+	}
+	return m.agent, nil
+}
+
+// The whole point of the fix: background workers must carry the agent's
+// configured request budget into ctx, or the agent-only preflight guard fails
+// closed with AgentBudgetWiringError and silently kills memory consolidation.
+func TestWithAgentRequestBudget_WiresConfiguredAgentBudget(t *testing.T) {
+	id := uuid.New()
+	agents := &budgetAgentStore{agent: &store.AgentData{ContextWindow: 128000, MaxTokens: 4096}}
+
+	ctx := withAgentRequestBudget(context.Background(), agents, id, "episodic-summary")
+
+	if got := store.AgentContextWindowFromContext(ctx); got != 128000 {
+		t.Fatalf("context window: want 128000, got %d", got)
+	}
+	if got := store.AgentMaxTokensFromContext(ctx); got != 4096 {
+		t.Fatalf("max tokens: want 4096, got %d", got)
+	}
+}
+
+func TestWithAgentRequestBudget_NilStoreFallsBackToDefaults(t *testing.T) {
+	ctx := withAgentRequestBudget(context.Background(), nil, uuid.New(), "dreaming-synthesis")
+
+	if got := store.AgentContextWindowFromContext(ctx); got != config.DefaultContextWindow {
+		t.Fatalf("context window: want default %d, got %d", config.DefaultContextWindow, got)
+	}
+	if got := store.AgentMaxTokensFromContext(ctx); got != config.DefaultMaxTokens {
+		t.Fatalf("max tokens: want default %d, got %d", config.DefaultMaxTokens, got)
+	}
+}
+
+func TestWithAgentRequestBudget_LookupErrorFallsBackToDefaults(t *testing.T) {
+	agents := &budgetAgentStore{err: errors.New("db down")}
+
+	ctx := withAgentRequestBudget(context.Background(), agents, uuid.New(), "episodic-summary")
+
+	if got := store.AgentContextWindowFromContext(ctx); got != config.DefaultContextWindow {
+		t.Fatalf("context window: want default %d, got %d", config.DefaultContextWindow, got)
+	}
+	if got := store.AgentMaxTokensFromContext(ctx); got != config.DefaultMaxTokens {
+		t.Fatalf("max tokens: want default %d, got %d", config.DefaultMaxTokens, got)
+	}
+}
+
+// A zero/partial agent row must not zero out the budget — the setters ignore
+// non-positive values, and the helper must supply defaults for the missing half.
+func TestWithAgentRequestBudget_ZeroFieldsUseDefaults(t *testing.T) {
+	agents := &budgetAgentStore{agent: &store.AgentData{ContextWindow: 0, MaxTokens: 0}}
+
+	ctx := withAgentRequestBudget(context.Background(), agents, uuid.New(), "episodic-summary")
+
+	if got := store.AgentContextWindowFromContext(ctx); got != config.DefaultContextWindow {
+		t.Fatalf("context window: want default %d, got %d", config.DefaultContextWindow, got)
+	}
+	if got := store.AgentMaxTokensFromContext(ctx); got != config.DefaultMaxTokens {
+		t.Fatalf("max tokens: want default %d, got %d", config.DefaultMaxTokens, got)
+	}
+}
diff --git a/internal/consolidation/dreaming_worker.go b/internal/consolidation/dreaming_worker.go
index 980413dd..1ddb294e 100644
--- a/internal/consolidation/dreaming_worker.go
+++ b/internal/consolidation/dreaming_worker.go
@@ -33,6 +33,7 @@ type dreamingWorker struct {
 	registry      *providers.Registry     // provider resolution
 	alertDeps     bgalert.AlertDeps
 	usageCaps     *usagecaps.Service
+	agents        store.AgentCRUDStore // for resolving per-agent request budget
 
 	// threshold/debounce are the global defaults. Per-agent overrides come
 	// from resolveConfig which reads the agent's MemoryConfig.Dreaming JSONB.
@@ -166,6 +167,14 @@ func (w *dreamingWorker) Handle(ctx context.Context, event eventbus.DomainEvent)
 		return nil
 	}
 
+	// Wire the agent's configured request budget so the synthesis call passes
+	// the agent-only preflight guard instead of failing closed.
+	if agentUUID, perr := uuid.Parse(agentID); perr == nil {
+		ctx = withAgentRequestBudget(ctx, w.agents, agentUUID, "dreaming-synthesis")
+	} else {
+		ctx = withAgentRequestBudget(ctx, w.agents, uuid.Nil, "dreaming-synthesis")
+	}
+
 	// Build LLM prompt and call provider.
 	synthesis, err := w.synthesize(ctx, provider, model, entries)
 	if err != nil {
diff --git a/internal/consolidation/episodic_worker.go b/internal/consolidation/episodic_worker.go
index 7fae25e7..61ddd207 100644
--- a/internal/consolidation/episodic_worker.go
+++ b/internal/consolidation/episodic_worker.go
@@ -25,6 +25,7 @@ type episodicWorker struct {
 	eventBus      eventbus.DomainEventBus
 	alertDeps     bgalert.AlertDeps
 	usageCaps     *usagecaps.Service
+	agents        store.AgentCRUDStore // resolves per-agent request budget for the preflight guard
 }
 
 // resolveProvider delegates to shared background provider resolution.
@@ -56,6 +57,10 @@ func (w *episodicWorker) Handle(ctx context.Context, event eventbus.DomainEvent)
 		return fmt.Errorf("episodic: invalid agent_id %q: %w", event.AgentID, err)
 	}
 	ctx = store.WithAgentID(ctx, agentUUID)
+	// Wire the calling agent's request budget so nested LLM summarization calls
+	// pass the agent-only preflight guard instead of failing closed with an
+	// AgentBudgetWiringError (purpose=episodic-summary).
+	ctx = withAgentRequestBudget(ctx, w.agents, agentUUID, "episodic-summary")
 
 	// Build source_id for idempotency
 	sourceID := fmt.Sprintf("%s:%d", payload.SessionKey, payload.CompactionCount)
diff --git a/internal/consolidation/workers.go b/internal/consolidation/workers.go
index 2c3be24e..9ed1561f 100644
--- a/internal/consolidation/workers.go
+++ b/internal/consolidation/workers.go
@@ -45,6 +45,7 @@ func Register(deps ConsolidationDeps) func() {
 		eventBus:      deps.EventBus,
 		alertDeps:     deps.AlertDeps,
 		usageCaps:     deps.UsageCaps,
+		agents:        deps.AgentStore,
 	}
 	semantic := &semanticWorker{
 		kgStore:   deps.KGStore,
@@ -66,6 +67,7 @@ func Register(deps ConsolidationDeps) func() {
 		threshold:     dreamingDefaultThreshold,
 		debounce:      dreamingDefaultDebounce,
 		resolveConfig: newAgentStoreResolver(deps.AgentStore),
+		agents:        deps.AgentStore,
 	}
 
 	unsub1 := deps.EventBus.Subscribe(eventbus.EventSessionCompleted, episodic.Handle)
diff --git a/internal/gateway/log_tee.go b/internal/gateway/log_tee.go
index 4ba33393..2d6a6101 100644
--- a/internal/gateway/log_tee.go
+++ b/internal/gateway/log_tee.go
@@ -23,6 +23,18 @@ var sensitiveKeys = []string{
 	"credential", "authorization", "cookie",
 }
 
+var safeTokenTelemetryKeys = map[string]bool{
+	"total_tokens":             true,
+	"prompt_tokens":            true,
+	"completion_tokens":        true,
+	"input_tokens":             true,
+	"output_tokens":            true,
+	"thinking_tokens":          true,
+	"last_prompt_tokens":       true,
+	"last_usage_prompt_tokens": true,
+	"total_prompt_tokens":      true,
+}
+
 // LogTee is a slog.Handler that forwards log records to subscribed WS clients
 // while delegating to an underlying handler for normal output.
 type LogTee struct {
@@ -347,6 +359,9 @@ func logLevelValue(v any) slog.Level {
 
 func isSensitiveKey(key string) bool {
 	lower := strings.ToLower(key)
+	if safeTokenTelemetryKeys[lower] {
+		return false
+	}
 	for _, s := range sensitiveKeys {
 		if strings.Contains(lower, s) {
 			return true
diff --git a/internal/gateway/log_tee_test.go b/internal/gateway/log_tee_test.go
index 7a310b73..f0c109ee 100644
--- a/internal/gateway/log_tee_test.go
+++ b/internal/gateway/log_tee_test.go
@@ -33,7 +33,12 @@ func TestLogTeeAggregateIncludesWithAttrsAndGroupEntries(t *testing.T) {
 func TestLogTeeAggregateRedactsSensitiveAttrs(t *testing.T) {
 	tee := NewLogTee(slog.NewTextHandler(io.Discard, nil))
 	rec := slog.NewRecord(time.Now(), slog.LevelInfo, "secret", 0)
-	rec.AddAttrs(slog.String("api_token", "leak"), slog.String("source", "test"))
+	rec.AddAttrs(
+		slog.String("api_token", "leak"),
+		slog.Int("total_tokens", 123),
+		slog.Int("last_prompt_tokens", 100),
+		slog.String("source", "test"),
+	)
 	if err := tee.Handle(context.Background(), rec); err != nil {
 		t.Fatal(err)
 	}
@@ -42,4 +47,10 @@ func TestLogTeeAggregateRedactsSensitiveAttrs(t *testing.T) {
 	if attrs["api_token"] != redactedValue {
 		t.Fatalf("attrs = %+v", attrs)
 	}
+	if attrs["total_tokens"] != "123" {
+		t.Fatalf("total_tokens = %#v, want 123", attrs["total_tokens"])
+	}
+	if attrs["last_prompt_tokens"] != "100" {
+		t.Fatalf("last_prompt_tokens = %#v, want 100", attrs["last_prompt_tokens"])
+	}
 }
diff --git a/internal/gateway/methods/chat.go b/internal/gateway/methods/chat.go
index 681fd6e3..8990108d 100644
--- a/internal/gateway/methods/chat.go
+++ b/internal/gateway/methods/chat.go
@@ -340,6 +340,12 @@ func (m *ChatMethods) dispatchChatSends(requests []chatSendRequest) {
 	if userID != "" {
 		runCtxBase = store.WithUserID(runCtxBase, userID)
 	}
+	// Team Work gate runs before Loop.injectContext; inject the resolved agent
+	// budget now so the classifier cannot fall back to model/provider guesses.
+	runCtxBase = agent.WithAgentBudget(runCtxBase, loop)
+	if uid := loop.UUID(); uid != uuid.Nil {
+		runCtxBase = store.WithAgentID(runCtxBase, uid)
+	}
 	gate := m.applyTeamWorkGate(runCtxBase, params, loop, sessionKey)
 	params.Message = gate.message
 	// Inject team dispatch tracker: gates team_tasks create (must search/list first)
diff --git a/internal/pipeline/context_stage.go b/internal/pipeline/context_stage.go
index 04e709a3..570e7fea 100644
--- a/internal/pipeline/context_stage.go
+++ b/internal/pipeline/context_stage.go
@@ -83,17 +83,10 @@ func (s *ContextStage) Execute(ctx context.Context, state *RunState) error {
 		state.Ctx = ctx
 	}
 
-	// 0.5. Resolve the effective context window for this run's provider/model.
-	// Done once here so PruneStage reads a stable value on every iteration and
-	// the budget can't drift if the model somehow changes mid-run. A zero
-	// result from the resolver (unknown model, no registry) leaves the field
-	// zero — PruneStage then falls back to Config.ContextWindow.
-	if s.deps.ResolveContextWindow != nil && state.Model != "" {
-		providerID := ""
-		if state.Provider != nil {
-			providerID = state.Provider.Name()
-		}
-		if cw := s.deps.ResolveContextWindow(providerID, state.Model); cw > 0 {
+	// 0.5. Snapshot the configured agent window once for this run. Model and
+	// provider do not participate in request-budget authority.
+	if s.deps.ResolveContextWindow != nil {
+		if cw := s.deps.ResolveContextWindow(); cw > 0 {
 			state.Context.EffectiveContextWindow = cw
 		}
 	}
diff --git a/internal/pipeline/deps.go b/internal/pipeline/deps.go
index 48cf8632..8fa8ce85 100644
--- a/internal/pipeline/deps.go
+++ b/internal/pipeline/deps.go
@@ -24,16 +24,16 @@ type PruneStats struct {
 // PipelineDeps bundles all external dependencies stages need.
 // Passed to NewDefaultPipeline; individual stages receive what they need via closure or direct field access.
 type PipelineDeps struct {
-	TokenCounter tokencount.TokenCounter
-	EventBus     eventbus.DomainEventBus
-	Config       PipelineConfig
+	TokenCounter  tokencount.TokenCounter
+	BudgetCounter tokencount.BudgetCounter
+	EventBus      eventbus.DomainEventBus
+	Config        PipelineConfig
 	// Hooks is the hook dispatcher. nil = no hooks (zero-overhead fast path).
 	Hooks hooks.Dispatcher
 
-	// ResolveContextWindow returns the effective context window (in tokens) for
-	// a given provider/model pair. Nil = always use Config.ContextWindow.
-	// Invoked ONCE per run by ContextStage and stored in RunState.Context.EffectiveContextWindow.
-	ResolveContextWindow func(provider, model string) int
+	// ResolveContextWindow returns this agent's configured context window.
+	// Model/provider are intentionally absent from the budget authority surface.
+	ResolveContextWindow func() int
 
 	// Callbacks from agent.Loop — Phase 8 adapter wires these.
 	EmitEvent func(event any)
@@ -125,9 +125,13 @@ type PipelineDeps struct {
 	// total (billing/AccumulateTokens); lastUsage is the final iteration's own
 	// usage — its ContextTokens() is the session's current context size
 	// (SetLastPromptTokens → sessions context display + compaction calibration).
+	// msgCount is the message count captured alongside lastUsage.
 	UpdateMetadata   func(ctx context.Context, sessionKey string, usage, lastUsage providers.Usage, msgCount int) error
 	BootstrapCleanup func(ctx context.Context, state *RunState) error
-	MaybeSummarize   func(ctx context.Context, sessionKey string)
+	// MaybeSummarize takes midLoopCompacted: when the final-request guard already
+	// compacted mid-loop this run, post-turn summarization lowers its trigger
+	// threshold so the compaction is PERSISTED (episodic Bug B / anti-loop).
+	MaybeSummarize func(ctx context.Context, sessionKey string, midLoopCompacted bool)
 }
 
 // FireHook is nil-safe. Returns FireResult{Decision: DecisionAllow} when no
diff --git a/internal/pipeline/final_request_guard.go b/internal/pipeline/final_request_guard.go
new file mode 100644
index 00000000..742cd239
--- /dev/null
+++ b/internal/pipeline/final_request_guard.go
@@ -0,0 +1,291 @@
+package pipeline
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"log/slog"
+	"strings"
+	"unicode/utf8"
+
+	"github.com/nextlevelbuilder/goclaw/internal/config"
+	"github.com/nextlevelbuilder/goclaw/internal/providers"
+)
+
+// FinalRequestEstimate describes the complete pre-call context budget for the
+// request that will actually be sent to the model.
+type FinalRequestEstimate struct {
+	MessageTokens       int
+	ToolTokens          int
+	InputTokens         int
+	OutputReserveTokens int
+	HardInputCapTokens  int
+	CompactTargetTokens int
+	ContextWindow       int
+	MaxRequestShare     float64
+}
+
+const defaultMaxRequestShare = 0.85
+
+func effectiveMaxRequestShare(cfg *config.CompactionConfig) float64 {
+	if cfg != nil && cfg.MaxRequestShare > 0 && cfg.MaxRequestShare <= 1 {
+		return cfg.MaxRequestShare
+	}
+	return defaultMaxRequestShare
+}
+
+func (s *ThinkStage) buildChatRequest(state *RunState, toolDefs []providers.ToolDefinition) providers.ChatRequest {
+	options := map[string]any{
+		providers.OptMaxTokens: s.deps.Config.MaxTokens,
+	}
+	return providers.ChatRequest{
+		Messages: state.Messages.All(),
+		Tools:    toolDefs,
+		Model:    state.Model,
+		Options:  options,
+	}
+}
+
+func (s *ThinkStage) finalRequestEstimate(state *RunState, req providers.ChatRequest) (FinalRequestEstimate, error) {
+	contextWindow := state.Context.EffectiveContextWindow
+	if contextWindow == 0 {
+		contextWindow = s.deps.Config.ContextWindow
+	}
+	if contextWindow <= 0 {
+		return FinalRequestEstimate{}, nil
+	}
+
+	messageTokens, toolTokens, err := countBudgetInput(s.deps, state.Model, req)
+	if err != nil {
+		return FinalRequestEstimate{}, err
+	}
+	outputReserve := s.deps.Config.MaxTokens
+	if outputReserve < 0 {
+		outputReserve = 0
+	}
+	share := effectiveMaxRequestShare(s.deps.Config.Compaction)
+	inputTokens := messageTokens + toolTokens
+	hardInputCap := contextWindow - outputReserve
+	shareTarget := int(float64(contextWindow)*share) - outputReserve
+	compactTarget := min(hardInputCap, shareTarget)
+	return FinalRequestEstimate{
+		MessageTokens:       messageTokens,
+		ToolTokens:          toolTokens,
+		InputTokens:         inputTokens,
+		OutputReserveTokens: outputReserve,
+		HardInputCapTokens:  hardInputCap,
+		CompactTargetTokens: compactTarget,
+		ContextWindow:       contextWindow,
+		MaxRequestShare:     share,
+	}, nil
+}
+
+func countBudgetInput(deps *PipelineDeps, model string, req providers.ChatRequest) (int, int, error) {
+	if deps != nil && deps.BudgetCounter != nil {
+		messages, err := deps.BudgetCounter.CountMessages(req.Messages)
+		if err != nil {
+			return 0, 0, fmt.Errorf("count request messages: %w", err)
+		}
+		tools, err := deps.BudgetCounter.CountToolSchemas(req.Tools)
+		if err != nil {
+			return 0, 0, fmt.Errorf("count request tools: %w", err)
+		}
+		return messages, tools, nil
+	}
+	// Isolated pipeline tests may still wire only the legacy counter. Runtime
+	// always provides BudgetCounter.
+	return countRequestMessages(deps, model, req.Messages), countRequestTools(deps, model, req.Tools), nil
+}
+
+func countRequestMessages(deps *PipelineDeps, model string, messages []providers.Message) int {
+	if deps != nil && deps.TokenCounter != nil {
+		return deps.TokenCounter.CountMessages(model, messages)
+	}
+	total := 0
+	for _, msg := range messages {
+		total += utf8.RuneCountInString(msg.Content)/3 + 4
+		for _, tc := range msg.ToolCalls {
+			total += utf8.RuneCountInString(tc.ID)/3 + utf8.RuneCountInString(tc.Name)/3
+		}
+	}
+	return total
+}
+
+func countRequestTools(deps *PipelineDeps, model string, tools []providers.ToolDefinition) int {
+	if len(tools) == 0 {
+		return 0
+	}
+	if deps != nil && deps.TokenCounter != nil {
+		return deps.TokenCounter.CountToolSchemas(model, tools)
+	}
+	blob, err := json.Marshal(tools)
+	if err != nil {
+		return 0
+	}
+	return utf8.RuneCountInString(string(blob)) / 3
+}
+
+func (e FinalRequestEstimate) withinLimit() bool {
+	return e.ContextWindow > 0 &&
+		e.HardInputCapTokens > 0 &&
+		e.CompactTargetTokens > 0 &&
+		e.InputTokens <= e.HardInputCapTokens &&
+		e.InputTokens <= e.CompactTargetTokens
+}
+
+func (s *ThinkStage) prepareFinalRequest(ctx context.Context, state *RunState, toolDefs []providers.ToolDefinition) (providers.ChatRequest, FinalRequestEstimate, error) {
+	req := s.buildChatRequest(state, toolDefs)
+	estimate, err := s.finalRequestEstimate(state, req)
+	if err != nil {
+		return req, estimate, err
+	}
+	if estimate.ContextWindow <= 0 {
+		// A nil counter means this lightweight pipeline instance did not opt into
+		// request budgeting (primarily isolated stage tests). Runtime wiring always
+		// provides a counter, so an unresolved runtime window still fails closed.
+		if s.deps.TokenCounter == nil {
+			return req, estimate, nil
+		}
+		return req, estimate, fmt.Errorf("context_window_unresolved: no configured agent context window")
+	}
+	if estimate.HardInputCapTokens <= 0 || estimate.CompactTargetTokens <= 0 {
+		s.logFinalRequestGuard(state, estimate, "abort", "invalid_budget")
+		return req, estimate, fmt.Errorf("final request context budget unavailable: context_window=%d output_reserve=%d hard_input_cap=%d compact_target=%d",
+			estimate.ContextWindow, estimate.OutputReserveTokens, estimate.HardInputCapTokens, estimate.CompactTargetTokens)
+	}
+	if estimate.withinLimit() {
+		s.logFinalRequestGuard(state, estimate, "allow", "initial")
+		return req, estimate, nil
+	}
+
+	s.logFinalRequestGuard(state, estimate, "reduce", "initial")
+	steps := []string{"prune_history", "compact_history", "shrink_memory"}
+	for _, step := range steps {
+		changed, err := s.reduceFinalRequestContext(ctx, state, estimate, step)
+		if err != nil {
+			return req, estimate, err
+		}
+		if !changed {
+			continue
+		}
+		req = s.buildChatRequest(state, toolDefs)
+		estimate, err = s.finalRequestEstimate(state, req)
+		if err != nil {
+			return req, estimate, err
+		}
+		if estimate.withinLimit() {
+			s.logFinalRequestGuard(state, estimate, "allow", step)
+			return req, estimate, nil
+		}
+		s.logFinalRequestGuard(state, estimate, "reduce", step)
+	}
+
+	s.logFinalRequestGuard(state, estimate, "abort", "exhausted")
+	return req, estimate, fmt.Errorf("final request context budget exceeded: estimated_input=%d compact_target=%d hard_input_cap=%d context_window=%d max_request_share=%.2f",
+		estimate.InputTokens, estimate.CompactTargetTokens, estimate.HardInputCapTokens, estimate.ContextWindow, estimate.MaxRequestShare)
+}
+
+func (s *ThinkStage) reduceFinalRequestContext(ctx context.Context, state *RunState, estimate FinalRequestEstimate, step string) (bool, error) {
+	switch step {
+	case "prune_history":
+		return s.pruneForFinalRequestBudget(state, estimate), nil
+	case "compact_history":
+		return s.compactForFinalRequestBudget(ctx, state)
+	case "shrink_memory":
+		return s.shrinkMemoryForFinalRequestBudget(state), nil
+	default:
+		return false, nil
+	}
+}
+
+func (s *ThinkStage) pruneForFinalRequestBudget(state *RunState, estimate FinalRequestEstimate) bool {
+	if s.deps.PruneMessages == nil {
+		return false
+	}
+	history := state.Messages.History()
+	if len(history) == 0 {
+		return false
+	}
+	fixedMessages := []providers.Message{state.Messages.System()}
+	fixedMessages = append(fixedMessages, state.Messages.Pending()...)
+	fixedMessageTokens := countRequestMessages(s.deps, state.Model, fixedMessages)
+	budget := estimate.CompactTargetTokens - estimate.ToolTokens - fixedMessageTokens
+	if budget <= 0 {
+		budget = 1
+	}
+	pruned, stats := s.deps.PruneMessages(history, budget)
+	changed := stats.ResultsTrimmed > 0 || stats.ResultsCleared > 0 || stats.Compacted || len(pruned) != len(history)
+	if !changed {
+		return false
+	}
+	if s.deps.SanitizeHistory != nil {
+		pruned, _ = s.deps.SanitizeHistory(pruned)
+	}
+	state.Messages.SetHistory(pruned)
+	return true
+}
+
+func (s *ThinkStage) compactForFinalRequestBudget(ctx context.Context, state *RunState) (bool, error) {
+	if s.deps.CompactMessages == nil {
+		return false, nil
+	}
+	history := state.Messages.History()
+	if len(history) == 0 {
+		return false, nil
+	}
+	savedPending := state.Messages.Pending()
+	compacted, err := s.deps.CompactMessages(ctx, history, state.Model)
+	if err != nil {
+		return false, fmt.Errorf("compact final request context: %w", err)
+	}
+	state.Messages.ReplaceHistory(compacted)
+	for _, msg := range savedPending {
+		state.Messages.AppendPending(msg)
+	}
+	state.Prune.MidLoopCompacted = true
+	state.Compact.CompactionCount++
+	return true, nil
+}
+
+func (s *ThinkStage) shrinkMemoryForFinalRequestBudget(state *RunState) bool {
+	section := strings.TrimSpace(state.Context.MemorySection)
+	if section == "" {
+		return false
+	}
+	sys := state.Messages.System()
+	content := sys.Content
+	candidates := []string{"\n\n" + state.Context.MemorySection, state.Context.MemorySection, section}
+	for _, candidate := range candidates {
+		if candidate == "" {
+			continue
+		}
+		if strings.Contains(content, candidate) {
+			sys.Content = strings.Replace(content, candidate, "", 1)
+			state.Messages.SetSystem(sys)
+			state.Context.MemorySection = ""
+			return true
+		}
+	}
+	return false
+}
+
+func (s *ThinkStage) logFinalRequestGuard(state *RunState, estimate FinalRequestEstimate, action, step string) {
+	if estimate.ContextWindow <= 0 {
+		return
+	}
+	slog.Info("final_context.guard",
+		"session_key", state.Input.SessionKey,
+		"run_id", state.RunID,
+		"model", state.Model,
+		"context_window", estimate.ContextWindow,
+		"max_request_share", estimate.MaxRequestShare,
+		"hard_input_cap_tokens", estimate.HardInputCapTokens,
+		"compact_target_input_tokens", estimate.CompactTargetTokens,
+		"message_tokens", estimate.MessageTokens,
+		"tool_tokens", estimate.ToolTokens,
+		"input_tokens", estimate.InputTokens,
+		"output_reserve_tokens", estimate.OutputReserveTokens,
+		"action", action,
+		"reduction_step", step,
+	)
+}
diff --git a/internal/pipeline/finalize_stage.go b/internal/pipeline/finalize_stage.go
index 0e212da4..91e840dd 100644
--- a/internal/pipeline/finalize_stage.go
+++ b/internal/pipeline/finalize_stage.go
@@ -120,7 +120,9 @@ func (s *FinalizeStage) Execute(ctx context.Context, state *RunState) error {
 		state.Tool.MediaResults = append(state.Tool.MediaResults, mr)
 	}
 
-	// 4. Flush remaining pending messages to session store
+	// 4. Flush remaining pending messages to session store.
+	// Capture the pre-flush history length so metadata msgCount reflects
+	// history + newly-persisted pending (matches upstream calibration).
 	historyCountBeforeFlush := len(state.Messages.History())
 	pending := state.Messages.FlushPending()
 	persistablePending := persistableMessages(pending)
@@ -145,9 +147,15 @@ func (s *FinalizeStage) Execute(ctx context.Context, state *RunState) error {
 		}
 	}
 
-	// 7. Post-run summarization (async background)
+	// 7. Post-run summarization (async background).
+	// Pass the mid-loop pressure flag: when the guard had to compact mid-loop this
+	// run, maybeSummarize uses a lower, unit-aligned threshold so the compaction is
+	// PERSISTED to the session (TruncateHistory + IncrementCompaction) instead of
+	// being thrown away — which both breaks the per-turn re-compaction loop (Việc 2)
+	// and advances the cumulative compaction count so episodic can progress (Việc 1-B).
+	// Both mid-loop paths (prune_stage + compactForFinalRequestBudget) set this flag.
 	if s.deps.MaybeSummarize != nil {
-		s.deps.MaybeSummarize(ctx, state.Input.SessionKey)
+		s.deps.MaybeSummarize(ctx, state.Input.SessionKey, state.Prune.MidLoopCompacted)
 	}
 
 	// 8. Emit session.completed for consolidation pipeline (episodic → semantic → dreaming).
diff --git a/internal/pipeline/pipeline_test.go b/internal/pipeline/pipeline_test.go
index bb0b7e4d..013d4fd3 100644
--- a/internal/pipeline/pipeline_test.go
+++ b/internal/pipeline/pipeline_test.go
@@ -400,6 +400,7 @@ func TestPipeline_BuildResultPopulatesRunID(t *testing.T) {
 	state := buildMinimalRunState()
 	state.Observe.FinalContent = "hello"
 	state.Think.TotalUsage = providers.Usage{PromptTokens: 10, CompletionTokens: 5, TotalTokens: 15}
+	state.Think.LastUsage = providers.Usage{PromptTokens: 7, CompletionTokens: 2, TotalTokens: 9}
 
 	result, err := p.Run(context.Background(), state)
 	if err != nil {
@@ -414,6 +415,9 @@ func TestPipeline_BuildResultPopulatesRunID(t *testing.T) {
 	if result.TotalUsage.TotalTokens != 15 {
 		t.Errorf("result.TotalUsage.TotalTokens = %d, want 15", result.TotalUsage.TotalTokens)
 	}
+	if result.LastUsage.TotalTokens != 9 {
+		t.Errorf("result.LastUsage.TotalTokens = %d, want 9", result.LastUsage.TotalTokens)
+	}
 	if result.Duration <= 0 {
 		t.Errorf("result.Duration = %v, want > 0", result.Duration)
 	}
@@ -506,6 +510,7 @@ func TestRunState_BuildResult_AllFields(t *testing.T) {
 	state.Observe.FinalContent = "final"
 	state.Observe.FinalThinking = "thinking"
 	state.Think.TotalUsage = providers.Usage{PromptTokens: 100, CompletionTokens: 50, TotalTokens: 150}
+	state.Think.LastUsage = providers.Usage{PromptTokens: 80, CompletionTokens: 20, TotalTokens: 100}
 	state.Iteration = 7
 	state.Tool.TotalToolCalls = 3
 	state.Tool.LoopKilled = true
@@ -528,6 +533,9 @@ func TestRunState_BuildResult_AllFields(t *testing.T) {
 	if r.TotalUsage.TotalTokens != 150 {
 		t.Errorf("TotalUsage.TotalTokens = %d", r.TotalUsage.TotalTokens)
 	}
+	if r.LastUsage.TotalTokens != 100 {
+		t.Errorf("LastUsage.TotalTokens = %d", r.LastUsage.TotalTokens)
+	}
 	if r.Iterations != 7 {
 		t.Errorf("Iterations = %d", r.Iterations)
 	}
diff --git a/internal/pipeline/prune_stage.go b/internal/pipeline/prune_stage.go
index dca6485a..15e5f2b5 100644
--- a/internal/pipeline/prune_stage.go
+++ b/internal/pipeline/prune_stage.go
@@ -26,7 +26,7 @@ func NewPruneStage(deps *PipelineDeps, memFlush *MemoryFlushStage) *PruneStage {
 	return &PruneStage{deps: deps, memoryFlush: memFlush, result: Continue}
 }
 
-func (s *PruneStage) Name() string       { return "prune" }
+func (s *PruneStage) Name() string        { return "prune" }
 func (s *PruneStage) Result() StageResult { return s.result }
 
 // defaultCachePruneTTL is used when cfg.TTL is empty or invalid.
@@ -74,6 +74,17 @@ func (s *PruneStage) Execute(ctx context.Context, state *RunState) error {
 	tokensBefore := historyTokens
 
 	softThreshold := budget * 70 / 100
+	slog.Info("context.preflight_budget",
+		"session_key", state.Input.SessionKey,
+		"context_window", contextWindow,
+		"effective_context_window", state.Context.EffectiveContextWindow,
+		"history_tokens", historyTokens,
+		"overhead_tokens", state.Context.OverheadTokens,
+		"max_tokens", s.deps.Config.MaxTokens,
+		"reserve_tokens", s.deps.Config.ReserveTokens,
+		"budget", budget,
+		"soft_threshold", softThreshold,
+	)
 	if historyTokens <= softThreshold {
 		return nil // under budget, no action needed
 	}
diff --git a/internal/pipeline/run_state.go b/internal/pipeline/run_state.go
index 4399f20f..745adfb5 100644
--- a/internal/pipeline/run_state.go
+++ b/internal/pipeline/run_state.go
@@ -78,6 +78,7 @@ func (rs *RunState) BuildResult() *RunResult {
 		Content:        rs.Observe.FinalContent,
 		Thinking:       rs.Observe.FinalThinking,
 		TotalUsage:     rs.Think.TotalUsage,
+		LastUsage:      rs.Think.LastUsage,
 		Iterations:     rs.Iteration,
 		ToolCalls:      rs.Tool.TotalToolCalls,
 		LoopKilled:     rs.Tool.LoopKilled,
diff --git a/internal/pipeline/stages_test.go b/internal/pipeline/stages_test.go
index fb7b2960..4d52eb00 100644
--- a/internal/pipeline/stages_test.go
+++ b/internal/pipeline/stages_test.go
@@ -3,6 +3,7 @@ package pipeline
 import (
 	"context"
 	"errors"
+	"log/slog"
 	"os"
 	"path/filepath"
 	"reflect"
@@ -353,7 +354,18 @@ func TestThinkStage_UsageAccumulation(t *testing.T) {
 			return &providers.ChatResponse{
 				Content:      "hello",
 				FinishReason: "stop",
-				Usage:        &providers.Usage{PromptTokens: 10, CompletionTokens: 5, TotalTokens: 15},
+				Usage: &providers.Usage{
+					PromptTokens:                      10 * callCount,
+					CompletionTokens:                  5,
+					TotalTokens:                       10*callCount + 5,
+					CacheCreationTokens:               2,
+					CacheReadTokens:                   3,
+					PromptTokensIncludeCachedSegments: callCount == 2,
+					ThinkingTokens:                    4,
+					RequestCount:                      1,
+					ImageCount:                        1,
+					WebSearchCount:                    1,
+				},
 			}, nil
 		},
 	}
@@ -364,14 +376,27 @@ func TestThinkStage_UsageAccumulation(t *testing.T) {
 	_ = stage.Execute(context.Background(), state)
 	_ = stage.Execute(context.Background(), state)
 
-	if state.Think.TotalUsage.PromptTokens != 20 {
-		t.Errorf("PromptTokens = %d, want 20", state.Think.TotalUsage.PromptTokens)
+	if state.Think.TotalUsage.PromptTokens != 30 {
+		t.Errorf("PromptTokens = %d, want 30", state.Think.TotalUsage.PromptTokens)
 	}
 	if state.Think.TotalUsage.CompletionTokens != 10 {
 		t.Errorf("CompletionTokens = %d, want 10", state.Think.TotalUsage.CompletionTokens)
 	}
-	if state.Think.TotalUsage.TotalTokens != 30 {
-		t.Errorf("TotalTokens = %d, want 30", state.Think.TotalUsage.TotalTokens)
+	if state.Think.TotalUsage.TotalTokens != 40 {
+		t.Errorf("TotalTokens = %d, want 40", state.Think.TotalUsage.TotalTokens)
+	}
+	if state.Think.TotalUsage.CacheCreationTokens != 4 || state.Think.TotalUsage.CacheReadTokens != 6 {
+		t.Errorf("cache tokens = %d/%d, want 4/6", state.Think.TotalUsage.CacheCreationTokens, state.Think.TotalUsage.CacheReadTokens)
+	}
+	if !state.Think.TotalUsage.PromptTokensIncludeCachedSegments {
+		t.Error("PromptTokensIncludeCachedSegments = false, want true")
+	}
+	if state.Think.TotalUsage.ThinkingTokens != 8 || state.Think.TotalUsage.RequestCount != 2 ||
+		state.Think.TotalUsage.ImageCount != 2 || state.Think.TotalUsage.WebSearchCount != 2 {
+		t.Errorf("extended usage = %+v, want thinking/request/image/web = 8/2/2/2", state.Think.TotalUsage)
+	}
+	if state.Think.LastUsage.PromptTokens != 20 || state.Think.LastUsage.TotalTokens != 25 {
+		t.Errorf("LastUsage = %+v, want last prompt=20 total=25", state.Think.LastUsage)
 	}
 }
 
@@ -3045,7 +3070,7 @@ func TestFinalizeStage_MaybeSummarize_Called(t *testing.T) {
 	t.Parallel()
 	summarizeCalled := false
 	deps := &PipelineDeps{
-		MaybeSummarize: func(_ context.Context, sessionKey string) {
+		MaybeSummarize: func(_ context.Context, sessionKey string, _ bool) {
 			if sessionKey == "sess-1" {
 				summarizeCalled = true
 			}
@@ -3408,3 +3433,251 @@ func TestToolStage_Parallel_DefersNonToolMessages(t *testing.T) {
 		t.Errorf("pending[3].Content = %q, want nudge", pending[3].Content)
 	}
 }
+
+func TestThinkStage_FinalRequestGuard_CompactsBeforeCallLLM(t *testing.T) {
+	t.Parallel()
+	compacted := false
+	called := false
+
+	deps := &PipelineDeps{
+		TokenCounter: finalRequestBudgetCounter{},
+		Config:       PipelineConfig{ContextWindow: 100, MaxTokens: 10, Compaction: &config.CompactionConfig{MaxRequestShare: 0.85}},
+		BuildFilteredTools: func(_ *RunState) ([]providers.ToolDefinition, error) {
+			return []providers.ToolDefinition{{
+				Type: "function",
+				Function: &providers.ToolFunctionSchema{
+					Name:        "large_tool",
+					Description: strings.Repeat("t", 50),
+					Parameters:  map[string]any{"type": "object"},
+				},
+			}}, nil
+		},
+		CompactMessages: func(_ context.Context, msgs []providers.Message, _ string) ([]providers.Message, error) {
+			compacted = true
+			if len(msgs) != 1 || !strings.Contains(msgs[0].Content, "long-history") {
+				t.Fatalf("CompactMessages got history = %#v", msgs)
+			}
+			return []providers.Message{{Role: "user", Content: "short"}}, nil
+		},
+		CallLLM: func(_ context.Context, _ *RunState, req providers.ChatRequest) (*providers.ChatResponse, error) {
+			called = true
+			if len(req.Messages) == 0 || req.Messages[len(req.Messages)-1].Content != "short" {
+				t.Fatalf("CallLLM received un-compacted request messages = %#v", req.Messages)
+			}
+			return &providers.ChatResponse{Content: "ok", FinishReason: "stop"}, nil
+		},
+	}
+	stage := NewThinkStage(deps)
+	state := defaultState()
+	state.Messages.SetHistory([]providers.Message{{Role: "user", Content: strings.Repeat("long-history", 10)}})
+
+	if err := stage.Execute(context.Background(), state); err != nil {
+		t.Fatalf("Execute() error: %v", err)
+	}
+	if !compacted {
+		t.Fatal("expected final request guard to compact before CallLLM")
+	}
+	if !called {
+		t.Fatal("expected CallLLM after compaction")
+	}
+}
+
+type finalRequestBudgetCounter struct{}
+
+func (finalRequestBudgetCounter) Count(_ string, text string) int { return len(text) }
+func (finalRequestBudgetCounter) CountMessages(_ string, msgs []providers.Message) int {
+	total := 0
+	for _, msg := range msgs {
+		total += len(msg.Content)
+	}
+	return total
+}
+func (finalRequestBudgetCounter) CountToolSchemas(_ string, tools []providers.ToolDefinition) int {
+	total := 0
+	for _, tool := range tools {
+		if tool.Function != nil {
+			total += len(tool.Function.Name) + len(tool.Function.Description)
+		}
+	}
+	return total
+}
+func (finalRequestBudgetCounter) ModelContextWindow(_ string) int { return 100 }
+
+func TestThinkStage_FinalRequestGuard_AllowsRequestUnderLimit(t *testing.T) {
+	t.Parallel()
+	compacted := false
+	called := false
+
+	deps := &PipelineDeps{
+		TokenCounter: finalRequestBudgetCounter{},
+		Config:       PipelineConfig{ContextWindow: 100, MaxTokens: 10, Compaction: &config.CompactionConfig{MaxRequestShare: 0.85}},
+		CompactMessages: func(_ context.Context, _ []providers.Message, _ string) ([]providers.Message, error) {
+			compacted = true
+			return nil, nil
+		},
+		CallLLM: func(_ context.Context, _ *RunState, _ providers.ChatRequest) (*providers.ChatResponse, error) {
+			called = true
+			return &providers.ChatResponse{Content: "ok", FinishReason: "stop"}, nil
+		},
+	}
+	stage := NewThinkStage(deps)
+	state := defaultState()
+	state.Messages.SetHistory([]providers.Message{{Role: "user", Content: "short"}})
+
+	if err := stage.Execute(context.Background(), state); err != nil {
+		t.Fatalf("Execute() error: %v", err)
+	}
+	if compacted {
+		t.Fatal("did not expect compaction for request under final context limit")
+	}
+	if !called {
+		t.Fatal("expected CallLLM for request under final context limit")
+	}
+}
+
+func TestThinkStage_FinalRequestGuard_AbortsWhenStillOverLimit(t *testing.T) {
+	t.Parallel()
+	called := false
+	compactCalls := 0
+
+	deps := &PipelineDeps{
+		TokenCounter: finalRequestBudgetCounter{},
+		Config:       PipelineConfig{ContextWindow: 100, MaxTokens: 10, Compaction: &config.CompactionConfig{MaxRequestShare: 0.85}},
+		CompactMessages: func(_ context.Context, _ []providers.Message, _ string) ([]providers.Message, error) {
+			compactCalls++
+			return []providers.Message{{Role: "user", Content: strings.Repeat("still-long", 20)}}, nil
+		},
+		CallLLM: func(_ context.Context, _ *RunState, _ providers.ChatRequest) (*providers.ChatResponse, error) {
+			called = true
+			return &providers.ChatResponse{Content: "should not call", FinishReason: "stop"}, nil
+		},
+	}
+	stage := NewThinkStage(deps)
+	state := defaultState()
+	state.Messages.SetHistory([]providers.Message{{Role: "user", Content: strings.Repeat("long-history", 10)}})
+
+	err := stage.Execute(context.Background(), state)
+	if err == nil {
+		t.Fatal("expected final request context budget error")
+	}
+	if !strings.Contains(err.Error(), "final request context budget exceeded") {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if compactCalls != 1 {
+		t.Fatalf("CompactMessages calls = %d, want 1", compactCalls)
+	}
+	if called {
+		t.Fatal("CallLLM must not run while final request remains over limit")
+	}
+}
+
+func TestFinalRequestEstimate_UsesAgentWindowBudgetMath(t *testing.T) {
+	t.Parallel()
+	tests := []struct {
+		name   string
+		window int
+		hard   int
+		target int
+	}{
+		{name: "200k", window: 200_000, hard: 191_808, target: 161_808},
+		{name: "128k", window: 128_000, hard: 119_808, target: 100_608},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			deps := &PipelineDeps{
+				TokenCounter: finalRequestBudgetCounter{},
+				Config: PipelineConfig{
+					ContextWindow: tt.window,
+					MaxTokens:     8192,
+					Compaction:    &config.CompactionConfig{MaxRequestShare: 0.85},
+				},
+			}
+			stage := NewThinkStage(deps)
+			estimate, err := stage.finalRequestEstimate(defaultState(), providers.ChatRequest{})
+			if err != nil {
+				t.Fatal(err)
+			}
+			if estimate.HardInputCapTokens != tt.hard || estimate.CompactTargetTokens != tt.target {
+				t.Fatalf("budget = hard %d target %d, want %d/%d", estimate.HardInputCapTokens, estimate.CompactTargetTokens, tt.hard, tt.target)
+			}
+		})
+	}
+}
+
+func TestThinkStage_FinalRequestGuard_RejectsUnresolvedWindow(t *testing.T) {
+	t.Parallel()
+	called := false
+	stage := NewThinkStage(&PipelineDeps{
+		TokenCounter: finalRequestBudgetCounter{},
+		CallLLM: func(context.Context, *RunState, providers.ChatRequest) (*providers.ChatResponse, error) {
+			called = true
+			return &providers.ChatResponse{}, nil
+		},
+	})
+	err := stage.Execute(context.Background(), defaultState())
+	if err == nil || !strings.Contains(err.Error(), "context_window_unresolved") {
+		t.Fatalf("Execute() error = %v, want context_window_unresolved", err)
+	}
+	if called {
+		t.Fatal("CallLLM must not run without a resolved context window")
+	}
+}
+
+// TestFinalRequestEstimate_OutputReserveIsAgentMaxTokens locks the agent-only
+// output reserve: the reserve equals the configured agent max_tokens exactly and
+// does NOT change with any provider/model reasoning transform. Model/provider
+// thinking bumps must never widen or narrow the pre-transport budget.
+func TestFinalRequestEstimate_OutputReserveIsAgentMaxTokens(t *testing.T) {
+	t.Parallel()
+	stage := NewThinkStage(&PipelineDeps{
+		TokenCounter: finalRequestBudgetCounter{},
+		Config: PipelineConfig{
+			ContextWindow: 200_000,
+			MaxTokens:     8192,
+			Compaction:    &config.CompactionConfig{MaxRequestShare: 0.85},
+		},
+	})
+
+	estimate, err := stage.finalRequestEstimate(defaultState(), stage.buildChatRequest(defaultState(), nil))
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Reserve == agent max_tokens (8192), independent of any reasoning transform.
+	if estimate.OutputReserveTokens != 8192 {
+		t.Fatalf("output reserve = %d, want 8192 (agent max_tokens)", estimate.OutputReserveTokens)
+	}
+	// Hard cap == window - agent max_tokens, exactly.
+	if estimate.HardInputCapTokens != 200_000-8192 {
+		t.Fatalf("hard cap = %d, want %d", estimate.HardInputCapTokens, 200_000-8192)
+	}
+}
+
+func TestInputContextTokens_CacheSemantics(t *testing.T) {
+	t.Parallel()
+	inclusive := providers.Usage{
+		PromptTokens: 100, CacheReadTokens: 80, CacheCreationTokens: 10,
+		PromptTokensIncludeCachedSegments: true,
+	}
+	if got := InputContextTokens(inclusive); got != 100 {
+		t.Fatalf("inclusive input = %d, want 100", got)
+	}
+	exclusive := inclusive
+	exclusive.PromptTokensIncludeCachedSegments = false
+	if got := InputContextTokens(exclusive); got != 190 {
+		t.Fatalf("exclusive input = %d, want 190", got)
+	}
+}
+
+func TestFinalContextActualLevel(t *testing.T) {
+	t.Parallel()
+	estimate := FinalRequestEstimate{InputTokens: 100, HardInputCapTokens: 120}
+	if level, reason := finalContextActualLevel(estimate, 100); level != slog.LevelDebug || reason != "" {
+		t.Fatalf("exact estimate = %v/%q, want debug/empty", level, reason)
+	}
+	if level, reason := finalContextActualLevel(estimate, 106); level != slog.LevelWarn || reason != "estimate_undercount" {
+		t.Fatalf("undercount = %v/%q, want warn/estimate_undercount", level, reason)
+	}
+	if level, reason := finalContextActualLevel(estimate, 121); level != slog.LevelWarn || reason != "hard_cap_exceeded" {
+		t.Fatalf("hard cap = %v/%q, want warn/hard_cap_exceeded", level, reason)
+	}
+}
diff --git a/internal/pipeline/substates.go b/internal/pipeline/substates.go
index 0954722e..64c6dd7d 100644
--- a/internal/pipeline/substates.go
+++ b/internal/pipeline/substates.go
@@ -118,6 +118,7 @@ type RunResult struct {
 	Content        string
 	Thinking       string
 	TotalUsage     providers.Usage
+	LastUsage      providers.Usage
 	Iterations     int
 	ToolCalls      int
 	LoopKilled     bool
diff --git a/internal/pipeline/think_stage.go b/internal/pipeline/think_stage.go
index 41e7ccb6..f4cc83c1 100644
--- a/internal/pipeline/think_stage.go
+++ b/internal/pipeline/think_stage.go
@@ -2,6 +2,7 @@ package pipeline
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"log/slog"
 	"strings"
@@ -53,14 +54,11 @@ func (s *ThinkStage) Execute(ctx context.Context, state *RunState) error {
 		state.Tool.AllowedTools = nil
 	}
 
-	// 3. Construct ChatRequest
-	req := providers.ChatRequest{
-		Messages: state.Messages.All(),
-		Tools:    toolDefs,
-		Model:    state.Model,
-		Options: map[string]any{
-			providers.OptMaxTokens: s.deps.Config.MaxTokens,
-		},
+	// 3. Construct the final ChatRequest and enforce the request-level
+	// context budget before any provider call is attempted.
+	req, estimate, err := s.prepareFinalRequest(ctx, state, toolDefs)
+	if err != nil {
+		return err
 	}
 
 	// 4. Call LLM (stream or sync — delegated to callback)
@@ -69,35 +67,54 @@ func (s *ThinkStage) Execute(ctx context.Context, state *RunState) error {
 	}
 	resp, err := s.deps.CallLLM(ctx, state, req)
 	if err != nil {
+		// Central hard-ceiling guard rejected the concrete request AFTER the
+		// callback appended its final directive/retry/reasoning mutations (which
+		// prepareFinalRequest could not see). Re-enter the full reduction chain
+		// against the current messages, rebuild, and retry this iteration. Only
+		// when reduction cannot bring the request under the ceiling do we abort —
+		// the guard already guaranteed zero transport calls were made.
+		if isRequestBudgetExceededErr(err) {
+			if state.Think.OverflowRetries >= maxBudgetReductionRetries {
+				return fmt.Errorf("request context budget exceeded after reduction: %w", err)
+			}
+			if s.reduceForBudgetExceeded(ctx, state) {
+				// This LLM call produced no response, so LastResponse still holds
+				// the PRIOR iteration's response. Clear it before returning Continue
+				// so ToolStage/ObserveStage in this same iteration do not re-execute
+				// the previous iteration's tool calls. The retry rebuilds and calls
+				// the model again on the next iteration.
+				state.Think.LastResponse = nil
+				return nil // Retry this iteration (Continue result) with reduced context.
+			}
+			return fmt.Errorf("request context budget exceeded, reduction exhausted: %w", err)
+		}
 		// Issue 958: Check for context overflow — attempt emergency compaction + retry
 		if isContextOverflowErr(err) {
 			if state.Think.OverflowRetries > 0 {
 				return fmt.Errorf("context overflow after compaction: %w", err)
 			}
 			if s.tryEmergencyCompaction(ctx, state, "context_overflow_error") {
+				// Same stale-response hazard as the budget path: no response was
+				// produced this iteration, so drop the prior one before retrying.
+				state.Think.LastResponse = nil
 				return nil // Retry this iteration (Continue result)
 			}
 		}
 		return fmt.Errorf("llm call: %w", err)
 	}
 
-	// 5. Accumulate usage across turns: base tokens, ThinkingTokens for reasoning
-	// models, and cache tokens. Cache read/creation must be summed too — otherwise
-	// the aggregated RunResult.Usage (and thus webhook usage + usage_events) reports
-	// zero cache even when each turn hit the prompt cache heavily.
+	// 5. Accumulate usage across turns and retain the usage snapshot for the
+	// request that was just sent. AddUsage preserves provider telemetry fields.
 	if resp.Usage != nil {
-		state.Think.TotalUsage.PromptTokens += resp.Usage.PromptTokens
-		state.Think.TotalUsage.CompletionTokens += resp.Usage.CompletionTokens
-		state.Think.TotalUsage.TotalTokens += resp.Usage.TotalTokens
-		state.Think.TotalUsage.ThinkingTokens += resp.Usage.ThinkingTokens
-		state.Think.TotalUsage.CacheReadTokens += resp.Usage.CacheReadTokens
-		state.Think.TotalUsage.CacheCreationTokens += resp.Usage.CacheCreationTokens
-		if resp.Usage.PromptTokensIncludeCachedSegments {
-			state.Think.TotalUsage.PromptTokensIncludeCachedSegments = true
-		}
+		// Log actual (post-call) usage vs the pre-call budget estimate (my guard
+		// observability), then accumulate the run-cumulative total.
+		s.logFinalRequestActual(ctx, state, estimate, *resp.Usage)
+		AddUsage(&state.Think.TotalUsage, *resp.Usage)
 		// Snapshot per-call usage: the LAST iteration's prompt size IS the
 		// session's current context. Keep the previous snapshot when a response
-		// carries no prompt tokens (e.g. providers that omit usage on some turns).
+		// carries no prompt tokens (e.g. providers that omit usage on some turns)
+		// — matches upstream 503909d3 behaviour, which never wipes a usable
+		// snapshot with an empty final response.
 		if resp.Usage.PromptTokens > 0 {
 			state.Think.LastUsage = *resp.Usage
 		}
@@ -108,6 +125,10 @@ func (s *ThinkStage) Execute(ctx context.Context, state *RunState) error {
 			return fmt.Errorf("llm response truncated before content after compaction")
 		}
 		if s.tryEmergencyCompaction(ctx, state, "empty_length_response") {
+			// LastResponse has NOT yet been updated to this empty response, so it
+			// still holds the prior iteration's result. Clear it so downstream
+			// stages this iteration don't act on the stale response during retry.
+			state.Think.LastResponse = nil
 			return nil // Retry next iteration with compacted history.
 		}
 		return fmt.Errorf("llm response truncated before content")
@@ -172,6 +193,46 @@ func (s *ThinkStage) Execute(ctx context.Context, state *RunState) error {
 	return nil
 }
 
+func (s *ThinkStage) logFinalRequestActual(ctx context.Context, state *RunState, estimate FinalRequestEstimate, usage providers.Usage) {
+	actualInput := InputContextTokens(usage)
+	if actualInput <= 0 || estimate.InputTokens <= 0 {
+		return
+	}
+
+	providerName := ""
+	if state.Provider != nil {
+		providerName = state.Provider.Name()
+	}
+	ratio := float64(actualInput) / float64(estimate.InputTokens)
+	level, reason := finalContextActualLevel(estimate, actualInput)
+	args := []any{
+		"run_id", state.RunID,
+		"iteration", state.Iteration,
+		"provider", providerName,
+		"model", state.Model,
+		"estimated_input", estimate.InputTokens,
+		"actual_input", actualInput,
+		"estimate_ratio", ratio,
+		"effective_window", estimate.ContextWindow,
+		"hard_input_cap", estimate.HardInputCapTokens,
+		"compact_target", estimate.CompactTargetTokens,
+	}
+	if reason != "" {
+		args = append(args, "reason", reason)
+	}
+	slog.Log(ctx, level, "final_context.actual", args...)
+}
+
+func finalContextActualLevel(estimate FinalRequestEstimate, actualInput int) (slog.Level, string) {
+	if actualInput > estimate.HardInputCapTokens {
+		return slog.LevelWarn, "hard_cap_exceeded"
+	}
+	if actualInput*100 > estimate.InputTokens*105 {
+		return slog.LevelWarn, "estimate_undercount"
+	}
+	return slog.LevelDebug, ""
+}
+
 func (s *ThinkStage) tryEmergencyCompaction(ctx context.Context, state *RunState, reason string) bool {
 	state.Think.OverflowRetries++
 	if s.deps.CompactMessages == nil {
@@ -297,3 +358,64 @@ func isContextOverflowErr(err error) bool {
 	lower := strings.ToLower(err.Error())
 	return providers.IsContextOverflowMessage(lower)
 }
+
+// maxBudgetReductionRetries bounds how many times a single iteration re-enters
+// reduction after the central request-budget guard rejects the built request.
+// Each retry runs one reduction step; three covers prune -> compact -> shrink.
+const maxBudgetReductionRetries = 3
+
+// contextBudgetExceededError is satisfied by the agent loop's
+// RequestBudgetExceededError. Detected via interface so this package does not
+// import the agent package (which would be a cycle).
+type contextBudgetExceededError interface {
+	ContextBudgetExceeded() bool
+}
+
+// isRequestBudgetExceededErr reports whether err (or anything it wraps) is a
+// request-level context-budget overflow raised by the central pre-transport
+// guard. Such an error guarantees no provider transport call was made.
+func isRequestBudgetExceededErr(err error) bool {
+	var budgetErr contextBudgetExceededError
+	if errors.As(err, &budgetErr) {
+		return budgetErr.ContextBudgetExceeded()
+	}
+	return false
+}
+
+// reduceForBudgetExceeded runs one pass of the reduction chain
+// (prune_history -> compact_history -> shrink_memory) against the current
+// state, stopping at the first step that changes anything. It increments
+// OverflowRetries so a stuck request eventually aborts. Returns true when some
+// reduction was applied and the iteration should retry.
+func (s *ThinkStage) reduceForBudgetExceeded(ctx context.Context, state *RunState) bool {
+	state.Think.OverflowRetries++
+
+	// Rebuild the estimate against current messages so pruning targets the
+	// right budget. Tools are rebuilt lazily by the retried iteration.
+	req := s.buildChatRequest(state, nil)
+	estimate, err := s.finalRequestEstimate(state, req)
+	if err != nil {
+		slog.Warn("request_budget.count_failed", "run_id", state.RunID, "error", err)
+		return false
+	}
+
+	steps := []string{"prune_history", "compact_history", "shrink_memory"}
+	for _, step := range steps {
+		changed, err := s.reduceFinalRequestContext(ctx, state, estimate, step)
+		if err != nil {
+			slog.Warn("request_budget.reduce_failed",
+				"run_id", state.RunID,
+				"step", step,
+				"error", err)
+			continue
+		}
+		if changed {
+			slog.Info("request_budget.reduced",
+				"run_id", state.RunID,
+				"step", step,
+				"overflow_retries", state.Think.OverflowRetries)
+			return true
+		}
+	}
+	return false
+}
diff --git a/internal/pipeline/think_stage_budget_test.go b/internal/pipeline/think_stage_budget_test.go
new file mode 100644
index 00000000..f9a09bd4
--- /dev/null
+++ b/internal/pipeline/think_stage_budget_test.go
@@ -0,0 +1,124 @@
+package pipeline
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	"github.com/nextlevelbuilder/goclaw/internal/providers"
+)
+
+// fakeBudgetErr satisfies the contextBudgetExceededError interface that
+// ThinkStage detects, standing in for agent.RequestBudgetExceededError without
+// importing the agent package (which would be an import cycle).
+type fakeBudgetErr struct{}
+
+func (fakeBudgetErr) Error() string               { return "context budget exceeded" }
+func (fakeBudgetErr) ContextBudgetExceeded() bool { return true }
+
+// TestThinkStage_BudgetExceeded_ReducesThenRetries verifies that when CallLLM
+// returns a request-budget-exceeded error (the central pre-transport guard
+// fired), the stage runs a reduction pass and returns Continue to retry the
+// iteration rather than aborting.
+func TestThinkStage_BudgetExceeded_ReducesThenRetries(t *testing.T) {
+	pruned := false
+	deps := &PipelineDeps{
+		Config: PipelineConfig{MaxIterations: 10, MaxTokens: 1000, ContextWindow: 200_000},
+		CallLLM: func(_ context.Context, _ *RunState, _ providers.ChatRequest) (*providers.ChatResponse, error) {
+			return nil, fakeBudgetErr{}
+		},
+		PruneMessages: func(msgs []providers.Message, _ int) ([]providers.Message, PruneStats) {
+			pruned = true
+			// Report a trim so reduceFinalRequestContext sees a change.
+			return msgs, PruneStats{ResultsTrimmed: 1}
+		},
+	}
+	stage := NewThinkStage(deps)
+	state := defaultState()
+	state.Messages.SetHistory([]providers.Message{{Role: "user", Content: "big history"}})
+
+	if err := stage.Execute(context.Background(), state); err != nil {
+		t.Fatalf("Execute() should retry after reduction, got error: %v", err)
+	}
+	if stage.Result() != Continue {
+		t.Errorf("Result() = %v, want Continue (retry after reduction)", stage.Result())
+	}
+	if !pruned {
+		t.Error("expected PruneMessages to run during budget reduction")
+	}
+	if state.Think.OverflowRetries != 1 {
+		t.Errorf("OverflowRetries = %d, want 1", state.Think.OverflowRetries)
+	}
+}
+
+// TestThinkStage_BudgetExceeded_AbortsWhenReductionExhausted verifies that when
+// no reduction step can change the request, the stage surfaces the budget error
+// instead of looping forever. The guard already guaranteed zero transport calls.
+func TestThinkStage_BudgetExceeded_AbortsWhenReductionExhausted(t *testing.T) {
+	deps := &PipelineDeps{
+		Config: PipelineConfig{MaxIterations: 10, MaxTokens: 1000, ContextWindow: 200_000},
+		CallLLM: func(_ context.Context, _ *RunState, _ providers.ChatRequest) (*providers.ChatResponse, error) {
+			return nil, fakeBudgetErr{}
+		},
+		// No PruneMessages / CompactMessages wired and no memory section, so
+		// every reduction step reports "no change".
+	}
+	stage := NewThinkStage(deps)
+	state := defaultState()
+
+	err := stage.Execute(context.Background(), state)
+	if err == nil {
+		t.Fatal("expected abort when reduction is exhausted, got nil")
+	}
+	if !errors.As(err, new(interface{ ContextBudgetExceeded() bool })) {
+		t.Fatalf("expected wrapped budget error, got %v", err)
+	}
+}
+
+// TestThinkThenTool_BudgetRetry_DoesNotReexecuteStaleToolCalls is the
+// full-pipeline regression guard for the stale-LastResponse hazard: when the
+// budget guard rejects iteration N+1's request, ThinkStage retries the
+// iteration, but ToolStage runs next in the SAME iteration and reads
+// state.Think.LastResponse. If ThinkStage left the PRIOR iteration's response
+// in place, ToolStage would re-execute those tool calls a second time. This
+// asserts ThinkStage clears LastResponse so ToolStage short-circuits.
+func TestThinkThenTool_BudgetRetry_DoesNotReexecuteStaleToolCalls(t *testing.T) {
+	executed := 0
+	deps := &PipelineDeps{
+		Config: PipelineConfig{MaxIterations: 10, MaxTokens: 1000, ContextWindow: 200_000},
+		CallLLM: func(_ context.Context, _ *RunState, _ providers.ChatRequest) (*providers.ChatResponse, error) {
+			return nil, fakeBudgetErr{}
+		},
+		PruneMessages: func(msgs []providers.Message, _ int) ([]providers.Message, PruneStats) {
+			return msgs, PruneStats{ResultsTrimmed: 1} // report a change so reduction "succeeds"
+		},
+		ExecuteToolCall: func(_ context.Context, _ *RunState, tc providers.ToolCall) ([]providers.Message, error) {
+			executed++
+			return []providers.Message{{Role: "tool", ToolCallID: tc.ID, Content: "ran"}}, nil
+		},
+	}
+	think := NewThinkStage(deps)
+	tool := NewToolStage(deps)
+	state := defaultState()
+	state.Messages.SetHistory([]providers.Message{{Role: "user", Content: "big history"}})
+
+	// Simulate a prior iteration having produced a tool-call response that was
+	// already executed. It must NOT be executed again when this iteration retries.
+	state.Think.LastResponse = &providers.ChatResponse{
+		FinishReason: "tool_calls",
+		ToolCalls:    []providers.ToolCall{{ID: "stale-1", Name: "write_file", Arguments: map[string]any{"path": "x"}}},
+	}
+
+	if err := think.Execute(context.Background(), state); err != nil {
+		t.Fatalf("ThinkStage.Execute() should retry, got error: %v", err)
+	}
+	if state.Think.LastResponse != nil {
+		t.Fatal("ThinkStage must clear LastResponse on budget-reduction retry")
+	}
+	if err := tool.Execute(context.Background(), state); err != nil {
+		t.Fatalf("ToolStage.Execute() error: %v", err)
+	}
+	if executed != 0 {
+		t.Fatalf("stale tool call re-executed %d time(s); want 0", executed)
+	}
+}
diff --git a/internal/pipeline/usage.go b/internal/pipeline/usage.go
new file mode 100644
index 00000000..626bbb42
--- /dev/null
+++ b/internal/pipeline/usage.go
@@ -0,0 +1,31 @@
+package pipeline
+
+import "github.com/nextlevelbuilder/goclaw/internal/providers"
+
+// InputContextTokens returns the provider-reported input occupancy for one
+// request. Anthropic-style usage reports cached segments separately, while
+// OpenAI-style prompt tokens already include them.
+func InputContextTokens(usage providers.Usage) int {
+	if usage.PromptTokensIncludeCachedSegments {
+		return usage.PromptTokens
+	}
+	return usage.PromptTokens + usage.CacheReadTokens + usage.CacheCreationTokens
+}
+
+// AddUsage accumulates provider usage while preserving telemetry fields that
+// are easy to drop when callers hand-roll partial sums.
+func AddUsage(dst *providers.Usage, src providers.Usage) {
+	if dst == nil {
+		return
+	}
+	dst.PromptTokens += src.PromptTokens
+	dst.CompletionTokens += src.CompletionTokens
+	dst.TotalTokens += src.TotalTokens
+	dst.CacheCreationTokens += src.CacheCreationTokens
+	dst.CacheReadTokens += src.CacheReadTokens
+	dst.PromptTokensIncludeCachedSegments = dst.PromptTokensIncludeCachedSegments || src.PromptTokensIncludeCachedSegments
+	dst.ThinkingTokens += src.ThinkingTokens
+	dst.RequestCount += src.RequestCount
+	dst.ImageCount += src.ImageCount
+	dst.WebSearchCount += src.WebSearchCount
+}
diff --git a/internal/store/context.go b/internal/store/context.go
index 50111216..026b1c57 100644
--- a/internal/store/context.go
+++ b/internal/store/context.go
@@ -37,6 +37,10 @@ const (
 	ShellDenyGroupsKey contextKey = "goclaw_shell_deny_groups"
 	// AgentKeyKey is the context key for the agent key/name (string identifier, e.g. "default").
 	AgentKeyKey contextKey = "goclaw_agent_key"
+	// AgentContextWindowKey carries the calling agent's configured context window.
+	AgentContextWindowKey contextKey = "goclaw_agent_context_window"
+	// AgentMaxTokensKey carries the calling agent's configured output reserve.
+	AgentMaxTokensKey contextKey = "goclaw_agent_max_tokens"
 	// TenantIDKey is the context key for the tenant UUID.
 	TenantIDKey contextKey = "goclaw_tenant_id"
 	// CrossTenantKey indicates the caller has cross-tenant access (owner/system admin).
@@ -139,6 +143,38 @@ func CredentialUserIDFromContext(ctx context.Context) string {
 	return UserIDFromContext(ctx)
 }
 
+// WithAgentContextWindow returns a context carrying the configured agent window.
+func WithAgentContextWindow(ctx context.Context, window int) context.Context {
+	if window <= 0 {
+		return ctx
+	}
+	return context.WithValue(ctx, AgentContextWindowKey, window)
+}
+
+// AgentContextWindowFromContext returns the configured agent window, or zero.
+func AgentContextWindowFromContext(ctx context.Context) int {
+	if v, ok := ctx.Value(AgentContextWindowKey).(int); ok && v > 0 {
+		return v
+	}
+	return 0
+}
+
+// WithAgentMaxTokens returns a context carrying the configured agent max_tokens.
+func WithAgentMaxTokens(ctx context.Context, maxTokens int) context.Context {
+	if maxTokens <= 0 {
+		return ctx
+	}
+	return context.WithValue(ctx, AgentMaxTokensKey, maxTokens)
+}
+
+// AgentMaxTokensFromContext returns the configured agent max_tokens, or zero.
+func AgentMaxTokensFromContext(ctx context.Context) int {
+	if v, ok := ctx.Value(AgentMaxTokensKey).(int); ok && v > 0 {
+		return v
+	}
+	return 0
+}
+
 // WithAgentID returns a new context with the given agent UUID.
 func WithAgentID(ctx context.Context, id uuid.UUID) context.Context {
 	return context.WithValue(ctx, AgentIDKey, id)
diff --git a/internal/tokencount/budget_counter.go b/internal/tokencount/budget_counter.go
new file mode 100644
index 00000000..a1f32cee
--- /dev/null
+++ b/internal/tokencount/budget_counter.go
@@ -0,0 +1,198 @@
+package tokencount
+
+import (
+	"bufio"
+	"bytes"
+	"compress/gzip"
+	_ "embed"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"strconv"
+	"strings"
+	"sync"
+
+	tiktoken "github.com/pkoukk/tiktoken-go"
+
+	"github.com/nextlevelbuilder/goclaw/internal/providers"
+)
+
+const (
+	budgetEncodingPattern = `(?i:'s|'t|'re|'ve|'m|'ll|'d)|[^\r\n\p{L}\p{N}]?\p{L}+|\p{N}{1,3}| ?[^\s\p{L}\p{N}]+[\r\n]*|\s*[\r\n]+|\s+(?!\S)|\s+`
+	budgetMessageOverhead = 4
+	budgetInlineMediaUnit = 1600
+)
+
+//go:embed cl100k_base.tiktoken.gz
+var budgetEncodingData []byte
+
+// BudgetCounter counts the complete input side of a model request with one
+// fixed, bundled GoClaw encoding. Its API intentionally has no model or provider
+// parameter: agent configuration is the only request-budget authority.
+type BudgetCounter interface {
+	CountText(text string) (int, error)
+	CountMessages(messages []providers.Message) (int, error)
+	CountToolSchemas(tools []providers.ToolDefinition) (int, error)
+	CountRequest(request providers.ChatRequest) (int, error)
+}
+
+type fixedBudgetCounter struct {
+	once    sync.Once
+	encoder *tiktoken.Tiktoken
+	err     error
+}
+
+// NewBudgetCounter returns GoClaw's fixed local complete-input counter.
+func NewBudgetCounter() BudgetCounter { return &fixedBudgetCounter{} }
+
+func (c *fixedBudgetCounter) CountText(text string) (int, error) {
+	encoder, err := c.load()
+	if err != nil {
+		return 0, err
+	}
+	return len(encoder.Encode(text, nil, nil)), nil
+}
+
+func (c *fixedBudgetCounter) CountMessages(messages []providers.Message) (int, error) {
+	encoder, err := c.load()
+	if err != nil {
+		return 0, err
+	}
+
+	total := 0
+	for _, message := range messages {
+		total += encodeBudgetText(encoder, message.Role)
+		total += encodeBudgetText(encoder, message.Content)
+		total += encodeBudgetText(encoder, message.Thinking)
+		total += encodeBudgetText(encoder, message.ToolCallID)
+		total += encodeBudgetText(encoder, message.Phase)
+		total += encodeBudgetText(encoder, string(message.RawAssistantContent))
+		total += budgetMessageOverhead
+		if message.IsError {
+			total++
+		}
+		for _, call := range message.ToolCalls {
+			total += encodeBudgetText(encoder, call.ID)
+			total += encodeBudgetText(encoder, call.Name)
+			total += encodeBudgetJSON(encoder, call.Arguments)
+			total += encodeBudgetJSON(encoder, call.Metadata)
+			total += encodeBudgetText(encoder, call.ParseError)
+		}
+		for _, image := range message.Images {
+			if image.Data != "" || image.URL != "" {
+				total += budgetInlineMediaUnit
+			}
+		}
+		for _, video := range message.Videos {
+			if video.Data != "" || video.URL != "" {
+				total += budgetInlineMediaUnit
+			}
+		}
+	}
+	return total, nil
+}
+
+func (c *fixedBudgetCounter) CountToolSchemas(tools []providers.ToolDefinition) (int, error) {
+	if len(tools) == 0 {
+		return 0, nil
+	}
+	encoder, err := c.load()
+	if err != nil {
+		return 0, err
+	}
+	blob, err := json.Marshal(tools)
+	if err != nil {
+		return 0, fmt.Errorf("marshal tool schemas for budget: %w", err)
+	}
+	return len(encoder.Encode(string(blob), nil, nil)), nil
+}
+
+func (c *fixedBudgetCounter) CountRequest(request providers.ChatRequest) (int, error) {
+	messages, err := c.CountMessages(request.Messages)
+	if err != nil {
+		return 0, err
+	}
+	tools, err := c.CountToolSchemas(request.Tools)
+	if err != nil {
+		return 0, err
+	}
+	return messages + tools, nil
+}
+
+func (c *fixedBudgetCounter) load() (*tiktoken.Tiktoken, error) {
+	c.once.Do(func() {
+		c.encoder, c.err = buildBudgetEncoder(budgetEncodingData)
+	})
+	return c.encoder, c.err
+}
+
+func buildBudgetEncoder(compressed []byte) (*tiktoken.Tiktoken, error) {
+	reader, err := gzip.NewReader(bytes.NewReader(compressed))
+	if err != nil {
+		return nil, fmt.Errorf("open bundled budget encoding: %w", err)
+	}
+	defer reader.Close()
+
+	ranks := make(map[string]int, 100_256)
+	scanner := bufio.NewScanner(reader)
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+		if line == "" {
+			continue
+		}
+		parts := strings.SplitN(line, " ", 2)
+		if len(parts) != 2 {
+			return nil, fmt.Errorf("invalid bundled budget encoding row")
+		}
+		token, decodeErr := base64.StdEncoding.DecodeString(parts[0])
+		if decodeErr != nil {
+			return nil, fmt.Errorf("decode bundled budget token: %w", decodeErr)
+		}
+		rank, parseErr := strconv.Atoi(parts[1])
+		if parseErr != nil {
+			return nil, fmt.Errorf("parse bundled budget rank: %w", parseErr)
+		}
+		ranks[string(token)] = rank
+	}
+	if err := scanner.Err(); err != nil {
+		return nil, fmt.Errorf("read bundled budget encoding: %w", err)
+	}
+
+	special := map[string]int{
+		tiktoken.ENDOFTEXT:   100257,
+		tiktoken.FIM_PREFIX:  100258,
+		tiktoken.FIM_MIDDLE:  100259,
+		tiktoken.FIM_SUFFIX:  100260,
+		tiktoken.ENDOFPROMPT: 100276,
+	}
+	core, err := tiktoken.NewCoreBPE(ranks, special, budgetEncodingPattern)
+	if err != nil {
+		return nil, fmt.Errorf("build bundled budget encoding: %w", err)
+	}
+	encoding := &tiktoken.Encoding{
+		Name:           "goclaw_budget_cl100k",
+		PatStr:         budgetEncodingPattern,
+		MergeableRanks: ranks,
+		SpecialTokens:  special,
+	}
+	specialSet := make(map[string]any, len(special))
+	for token := range special {
+		specialSet[token] = true
+	}
+	return tiktoken.NewTiktoken(core, encoding, specialSet), nil
+}
+
+func encodeBudgetText(encoder *tiktoken.Tiktoken, text string) int {
+	if text == "" {
+		return 0
+	}
+	return len(encoder.Encode(text, nil, nil))
+}
+
+func encodeBudgetJSON(encoder *tiktoken.Tiktoken, value any) int {
+	blob, err := json.Marshal(value)
+	if err != nil || string(blob) == "null" || string(blob) == "{}" {
+		return 0
+	}
+	return len(encoder.Encode(string(blob), nil, nil))
+}
diff --git a/internal/tokencount/cl100k_base.tiktoken.gz b/internal/tokencount/cl100k_base.tiktoken.gz
new file mode 100644
index 00000000..f040af8b
Binary files /dev/null and b/internal/tokencount/cl100k_base.tiktoken.gz differ
diff --git a/internal/tokencount/fallback_counter.go b/internal/tokencount/fallback_counter.go
index d06bb92f..e98b45cc 100644
--- a/internal/tokencount/fallback_counter.go
+++ b/internal/tokencount/fallback_counter.go
@@ -10,43 +10,76 @@ import (
 	"github.com/nextlevelbuilder/goclaw/internal/providers"
 )
 
-// FallbackCounter uses rune-count/3 heuristic (matches v2 behavior).
-// Used when tiktoken-go is unavailable or model is unknown.
+// FallbackCounter is the BEST-EFFORT heuristic counter used when tiktoken-go is
+// unavailable or the model is unknown (e.g. 9router brand models that match no
+// registry prefix). It is NOT a proven token bound: real tokenizers vary by
+// language, and dense scripts like Vietnamese tokenize at ~2 chars/token or
+// worse. Because the pre-transport guard treats this count as its ceiling, the
+// heuristic deliberately uses a CONSERVATIVE chars-per-token ratio so it errs
+// toward over-counting (compact/block early) rather than under-counting (send an
+// oversized request). The only way to a provable ceiling for an un-tokenizable
+// model is to register it with a real tokenizer or use the provider's own token
+// count.
 type FallbackCounter struct{}
 
 func NewFallbackCounter() *FallbackCounter { return &FallbackCounter{} }
 
+// fallbackCharsPerToken is the conservative chars-per-token divisor for the
+// guard-facing count methods. Lower than a naive ~3-4 chars/token so mixed
+// Vietnamese/code content is over-counted rather than under-counted. This is a
+// safety heuristic, not an exact tokenization.
+const fallbackCharsPerToken = 2
+
 func (c *FallbackCounter) Count(_ string, text string) int {
-	return utf8.RuneCountInString(text) / 3
+	return utf8.RuneCountInString(text) / fallbackCharsPerToken
 }
 
 func (c *FallbackCounter) CountMessages(_ string, msgs []providers.Message) int {
 	total := 0
 	for _, m := range msgs {
-		total += utf8.RuneCountInString(m.Content)/3 + PerMessageOverhead
+		total += utf8.RuneCountInString(m.Content)/fallbackCharsPerToken + PerMessageOverhead
+		// Match tiktokenCounter.CountMessages coverage so the fallback path
+		// applies the same best-effort ceiling (thinking, tool-result id, raw
+		// blocks, tool args, media all count toward the wire payload).
+		total += utf8.RuneCountInString(m.Thinking) / fallbackCharsPerToken
+		total += utf8.RuneCountInString(m.ToolCallID) / fallbackCharsPerToken
+		total += utf8.RuneCountInString(string(m.RawAssistantContent)) / fallbackCharsPerToken
 		for _, tc := range m.ToolCalls {
-			total += utf8.RuneCountInString(tc.ID)/3 + utf8.RuneCountInString(tc.Name)/3
-			for k, v := range tc.Arguments {
-				total += utf8.RuneCountInString(k) / 3
-				if s, ok := v.(string); ok {
-					total += utf8.RuneCountInString(s) / 3
-				} else {
-					total += 10
-				}
+			total += utf8.RuneCountInString(tc.ID)/fallbackCharsPerToken + utf8.RuneCountInString(tc.Name)/fallbackCharsPerToken
+			if b, err := json.Marshal(tc.Arguments); err == nil {
+				total += utf8.RuneCountInString(string(b)) / fallbackCharsPerToken
 			}
 		}
+		total += fallbackMediaTokenCost(m)
 	}
 	return total
 }
 
-// CountToolSchemas returns rune/3 heuristic count for the JSON-serialised tool list.
-// Returns 0 for nil or empty slice.
+// fallbackMediaTokenCost mirrors mediaTokenCost for the heuristic counter.
+func fallbackMediaTokenCost(m providers.Message) int {
+	const perInlineMediaItem = 1600
+	cost := 0
+	for _, img := range m.Images {
+		if img.Data != "" || img.URL != "" {
+			cost += perInlineMediaItem
+		}
+	}
+	for _, vid := range m.Videos {
+		if vid.Data != "" || vid.URL != "" {
+			cost += perInlineMediaItem
+		}
+	}
+	return cost
+}
+
+// CountToolSchemas returns a conservative heuristic count for the JSON-serialised
+// tool list. Returns 0 for nil or empty slice.
 func (c *FallbackCounter) CountToolSchemas(_ string, tools []providers.ToolDefinition) int {
 	if len(tools) == 0 {
 		return 0
 	}
 	blob, _ := json.Marshal(tools)
-	return utf8.RuneCountInString(string(blob)) / 3
+	return utf8.RuneCountInString(string(blob)) / fallbackCharsPerToken
 }
 
 // ModelContextWindow uses longest-prefix-match to avoid ambiguity
diff --git a/internal/tokencount/tiktoken_counter.go b/internal/tokencount/tiktoken_counter.go
index 74d4d767..c28b0168 100644
--- a/internal/tokencount/tiktoken_counter.go
+++ b/internal/tokencount/tiktoken_counter.go
@@ -53,9 +53,17 @@ func (c *tiktokenCounter) CountMessages(model string, msgs []providers.Message)
 		return c.fallback.CountMessages(model, msgs)
 	}
 
+	// The per-message count depends on the tokenizer, so the cache key MUST
+	// include the tokenizer identity. Otherwise a message counted with model A's
+	// tokenizer (e.g. cl100k for Claude) would return that stale count when the
+	// same message is re-counted for model B on a different tokenizer (e.g.
+	// o200k for GPT-4o) — most visibly on fallback candidates. Models that share
+	// a tokenizer correctly share cache entries.
+	tokenizerID := resolveModelInfo(model).TokenizerID
+
 	total := 0
 	for _, m := range msgs {
-		hash := messageHash(m)
+		hash := messageHash(tokenizerID, m)
 
 		c.mu.RLock()
 		cached, ok := c.msgCache[hash]
@@ -67,10 +75,29 @@ func (c *tiktokenCounter) CountMessages(model string, msgs []providers.Message)
 		}
 
 		count := len(enc.Encode(m.Content, nil, nil)) + PerMessageOverhead
+		// Thinking/reasoning is sent back to the provider on subsequent turns
+		// (Anthropic requires it for tool-use passback), so it counts toward input.
+		if m.Thinking != "" {
+			count += len(enc.Encode(m.Thinking, nil, nil))
+		}
+		// Tool result correlation id (role="tool" messages).
+		if m.ToolCallID != "" {
+			count += len(enc.Encode(m.ToolCallID, nil, nil))
+		}
+		// Raw assistant content blocks (Anthropic thinking-block passback) are
+		// serialized into the wire payload verbatim — count their bytes.
+		if len(m.RawAssistantContent) > 0 {
+			count += len(enc.Encode(string(m.RawAssistantContent), nil, nil))
+		}
 		for _, tc := range m.ToolCalls {
 			count += len(enc.Encode(tc.Name, nil, nil))
 			count += len(enc.Encode(tc.ID, nil, nil))
+			// Tool call arguments are serialized as JSON into the request and can
+			// dominate token cost; the previous counter ignored them entirely.
+			count += encodeToolArgs(enc, tc.Arguments)
 		}
+		// Media (images/videos) carry a per-item token cost when sent inline.
+		count += mediaTokenCost(m)
 
 		c.mu.Lock()
 		c.msgCache[hash] = count
@@ -167,19 +194,84 @@ func resolveModelInfo(model string) ModelInfo {
 }
 
 // messageHash computes FNV-1a hash of message content for cache keying.
-func messageHash(m providers.Message) uint64 {
+// It MUST cover every field that CountMessages encodes; otherwise a payload
+// whose thinking/args/tool-result/raw-blocks/media changed but whose Content is
+// unchanged would return a stale cached count for a different wire payload.
+// The tokenizer ID is folded in first because the token count is
+// tokenizer-dependent: the same message yields different counts under cl100k vs
+// o200k, so counts must not be shared across tokenizers.
+func messageHash(tokenizerID TokenizerID, m providers.Message) uint64 {
 	h := fnv.New64a()
+	h.Write([]byte(tokenizerID))
+	h.Write([]byte{0}) // separator
 	h.Write([]byte(m.Role))
 	h.Write([]byte{0}) // separator
 	h.Write([]byte(m.Content))
+	h.Write([]byte{0})
+	h.Write([]byte(m.Thinking))
+	h.Write([]byte{0})
+	h.Write([]byte(m.ToolCallID))
+	h.Write([]byte{0})
+	h.Write(m.RawAssistantContent)
 	for _, tc := range m.ToolCalls {
 		h.Write([]byte{0})
 		h.Write([]byte(tc.ID))
 		h.Write([]byte(tc.Name))
+		if b, err := json.Marshal(tc.Arguments); err == nil {
+			h.Write(b)
+		}
+	}
+	for _, img := range m.Images {
+		h.Write([]byte{0})
+		h.Write([]byte(img.MimeType))
+		h.Write([]byte(img.URL))
+	}
+	for _, vid := range m.Videos {
+		h.Write([]byte{0})
+		h.Write([]byte(vid.MimeType))
+		h.Write([]byte(vid.URL))
 	}
 	return h.Sum64()
 }
 
+// encodeToolArgs returns the BPE token count of a tool call's arguments as they
+// are serialized into the request payload (JSON). Returns 0 when arguments are
+// empty or cannot be marshalled.
+func encodeToolArgs(enc *tiktoken.Tiktoken, args map[string]any) int {
+	if len(args) == 0 {
+		return 0
+	}
+	b, err := json.Marshal(args)
+	if err != nil {
+		return 0
+	}
+	return len(enc.Encode(string(b), nil, nil))
+}
+
+// mediaTokenCost approximates the token cost of inline media on a message.
+// This is BEST-EFFORT, not a proven bound: a flat per-item estimate can
+// under-count a large inline video whose true token cost far exceeds it. It
+// exists so inline media is not counted as zero. Tool-internal media that
+// travels out-of-band (provider file/transcription APIs) is measured separately
+// by size in the caps guard (EstimateOutOfBandMediaTokens); this path only
+// covers media actually embedded in the message. Callers that persist media as
+// MediaRefs (not inlined) incur no cost here.
+func mediaTokenCost(m providers.Message) int {
+	const perInlineMediaItem = 1600 // best-effort estimate per inline image/video
+	cost := 0
+	for _, img := range m.Images {
+		if img.Data != "" || img.URL != "" {
+			cost += perInlineMediaItem
+		}
+	}
+	for _, vid := range m.Videos {
+		if vid.Data != "" || vid.URL != "" {
+			cost += perInlineMediaItem
+		}
+	}
+	return cost
+}
+
 // NewTokenCounter creates the best available counter.
 // Uses tiktoken if requested, falls back to rune/3 heuristic.
 func NewTokenCounter(useTiktoken bool) TokenCounter {
diff --git a/internal/tokencount/tiktoken_counter_test.go b/internal/tokencount/tiktoken_counter_test.go
index 85bb00f3..5d8fd7ff 100644
--- a/internal/tokencount/tiktoken_counter_test.go
+++ b/internal/tokencount/tiktoken_counter_test.go
@@ -59,6 +59,38 @@ func TestCountMessages_Cache(t *testing.T) {
 	}
 }
 
+// TestCountMessages_CacheIsTokenizerScoped is the regression guard for the
+// stale cross-tokenizer count bug: the same message counted under a cl100k
+// model then an o200k model must re-encode (different tokenizer) rather than
+// return the first tokenizer's cached count. This matters most on fallback
+// candidates that switch tokenizer mid-run.
+func TestCountMessages_CacheIsTokenizerScoped(t *testing.T) {
+	c := NewTiktokenCounter()
+	// A string whose cl100k and o200k token counts differ.
+	msgs := []providers.Message{
+		{Role: "user", Content: "internationalization tokenization pseudopseudohypoparathyroidism"},
+	}
+
+	cl := c.CountMessages("claude-sonnet-4-5-20250929", msgs) // cl100k_base
+	o2 := c.CountMessages("gpt-4o", msgs)                     // o200k_base
+
+	if cl <= 0 || o2 <= 0 {
+		t.Fatalf("counts must be positive: cl=%d o2=%d", cl, o2)
+	}
+	// The two tokenizers should produce different counts for this string; if they
+	// were sharing a cache entry, o2 would equal cl (the stale bug).
+	if cl == o2 {
+		t.Fatalf("cl100k and o200k returned identical count %d — cache is not tokenizer-scoped", cl)
+	}
+	// Two distinct tokenizers => two cache entries for the one message.
+	c.mu.RLock()
+	cacheLen := len(c.msgCache)
+	c.mu.RUnlock()
+	if cacheLen != 2 {
+		t.Errorf("cache has %d entries, want 2 (one per tokenizer)", cacheLen)
+	}
+}
+
 func TestCountMessages_Overhead(t *testing.T) {
 	c := NewTiktokenCounter()
 	msgs := []providers.Message{
diff --git a/internal/tools/read_audio_resolve.go b/internal/tools/read_audio_resolve.go
index bbfdcc0b..33ce7eda 100644
--- a/internal/tools/read_audio_resolve.go
+++ b/internal/tools/read_audio_resolve.go
@@ -98,7 +98,7 @@ func (t *ReadAudioTool) callProvider(ctx context.Context, cp credentialProvider,
 				Model:    model,
 				Options:  map[string]any{"max_tokens": 16384},
 			}
-			reservation, reserveErr := reserveToolLLMUsage(ctx, t.usageCaps, t.Name(), providerName, model, chatReq)
+			reservation, reserveErr := reserveToolLLMUsageWithMedia(ctx, t.usageCaps, t.Name(), providerName, model, chatReq, mime, data)
 			if reserveErr != nil {
 				return nil, nil, reserveErr
 			}
@@ -120,7 +120,7 @@ func (t *ReadAudioTool) callProvider(ctx context.Context, cp credentialProvider,
 				Model:    model,
 				Options:  map[string]any{"max_tokens": 16384},
 			}
-			reservation, reserveErr := reserveToolLLMUsage(ctx, t.usageCaps, t.Name(), providerName, model, chatReq)
+			reservation, reserveErr := reserveToolLLMUsageWithMedia(ctx, t.usageCaps, t.Name(), providerName, model, chatReq, mime, data)
 			if reserveErr != nil {
 				return nil, nil, reserveErr
 			}
@@ -142,7 +142,7 @@ func (t *ReadAudioTool) callProvider(ctx context.Context, cp credentialProvider,
 				Model:    model,
 				Options:  map[string]any{"max_tokens": 16384},
 			}
-			reservation, reserveErr := reserveToolLLMUsage(ctx, t.usageCaps, t.Name(), providerName, model, chatReq)
+			reservation, reserveErr := reserveToolLLMUsageWithMedia(ctx, t.usageCaps, t.Name(), providerName, model, chatReq, mime, data)
 			if reserveErr != nil {
 				return nil, nil, reserveErr
 			}
diff --git a/internal/tools/read_document_resolve.go b/internal/tools/read_document_resolve.go
index 24de1584..d32ceed1 100644
--- a/internal/tools/read_document_resolve.go
+++ b/internal/tools/read_document_resolve.go
@@ -160,7 +160,7 @@ func (t *ReadDocumentTool) callProvider(ctx context.Context, cp credentialProvid
 			Model:   model,
 			Options: map[string]any{"max_tokens": 16384},
 		}
-		reservation, reserveErr := reserveToolLLMUsage(ctx, t.usageCaps, t.Name(), providerName, model, chatReq)
+		reservation, reserveErr := reserveToolLLMUsageWithMedia(ctx, t.usageCaps, t.Name(), providerName, model, chatReq, mime, data)
 		if reserveErr != nil {
 			return nil, nil, reserveErr
 		}
diff --git a/internal/tools/read_video_resolve.go b/internal/tools/read_video_resolve.go
index 646068cb..0a6d0a0a 100644
--- a/internal/tools/read_video_resolve.go
+++ b/internal/tools/read_video_resolve.go
@@ -13,6 +13,7 @@ import (
 
 	"github.com/nextlevelbuilder/goclaw/internal/providers"
 	"github.com/nextlevelbuilder/goclaw/internal/security"
+	usagecaps "github.com/nextlevelbuilder/goclaw/internal/usage/caps"
 )
 
 // resolveVideoFile finds the video file path from context MediaRefs.
@@ -89,7 +90,17 @@ func (t *ReadVideoTool) callProvider(ctx context.Context, cp credentialProvider,
 			Model:    model,
 			Options:  map[string]any{"max_tokens": 16384},
 		}
-		reservation, reserveErr := reserveToolLLMUsage(ctx, t.usageCaps, t.Name(), providerName, model, chatReq)
+		// The reservation differs by transport. The base64 path has the real
+		// bytes now and counts them. The URL-stream path never buffers the
+		// payload, so it cannot prove completeInput and fails closed under an
+		// agent budget rather than trusting Content-Length.
+		var reservation *usagecaps.Reservation
+		var reserveErr error
+		if videoURL != "" {
+			reservation, reserveErr = reserveToolLLMUsageUnverifiableMedia(ctx, t.usageCaps, t.Name(), providerName, model, chatReq)
+		} else {
+			reservation, reserveErr = reserveToolLLMUsageWithMedia(ctx, t.usageCaps, t.Name(), providerName, model, chatReq, mime, data)
+		}
 		if reserveErr != nil {
 			return nil, nil, reserveErr
 		}
diff --git a/internal/tools/read_video_test.go b/internal/tools/read_video_test.go
index 3440f947..abd55adf 100644
--- a/internal/tools/read_video_test.go
+++ b/internal/tools/read_video_test.go
@@ -8,6 +8,7 @@ import (
 	"testing"
 
 	"github.com/nextlevelbuilder/goclaw/internal/security"
+	"github.com/nextlevelbuilder/goclaw/internal/store"
 )
 
 type mockCredentialProvider struct {
@@ -52,72 +53,50 @@ func TestReadVideo_PrivateURL_Error(t *testing.T) {
 	}
 }
 
-func TestReadVideo_GeminiURL_Validation(t *testing.T) {
+// TestReadVideo_GeminiURL_FailsClosedUnderAgentBudget locks the fail-closed
+// contract for a streamed video URL. The stream is never buffered, so its bytes
+// cannot be counted into completeInput; under an agent budget the call refuses
+// before any transport rather than undercounting. Because every tool LLM call
+// is agent-scoped in production, this refusal — not the downstream
+// Content-Length / 2 GB / HTTP-status checks — is the reachable behavior. Those
+// transport validations remain in callProvider for defense in depth but are
+// unreachable once an agent budget is present.
+func TestReadVideo_GeminiURL_FailsClosedUnderAgentBudget(t *testing.T) {
 	security.SetAllowLoopbackForTest(true)
 	defer security.SetAllowLoopbackForTest(false)
 
-	// Missing Content-Length should fail before upload.
-	ts1 := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Transfer-Encoding", "chunked")
-		w.Write([]byte("chunked data mock video"))
+	// A server that would otherwise satisfy the static-streaming constraints
+	// (valid Content-Length, 2xx). The call must still fail closed before it is
+	// ever contacted, because the payload cannot be counted.
+	hits := 0
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		hits++
+		w.Header().Set("Content-Length", "1024")
+		w.WriteHeader(http.StatusOK)
+		w.Write(make([]byte, 1024))
 	}))
-	defer ts1.Close()
+	defer ts.Close()
 
 	tool := NewReadVideoTool(nil, nil)
 	cp := &mockCredentialProvider{apiKey: "test-key"}
 
-	params1 := map[string]any{
+	ctx := store.WithAgentContextWindow(context.Background(), 200_000)
+	ctx = store.WithAgentMaxTokens(ctx, 32_000)
+
+	params := map[string]any{
 		"prompt":         "describe this video",
-		"url":            ts1.URL,
+		"url":            ts.URL,
 		"_provider_type": "gemini",
 	}
 
-	_, _, err := tool.callProvider(context.Background(), cp, "gemini", "gemini-2.5-flash", params1)
+	_, _, err := tool.callProvider(ctx, cp, "gemini", "gemini-2.5-flash", params)
 	if err == nil {
-		t.Fatalf("expected error for missing Content-Length")
+		t.Fatalf("expected fail-closed for an unverifiable streamed video URL under an agent budget")
 	}
-	if !strings.Contains(err.Error(), "URL does not support static streaming") {
-		t.Errorf("unexpected error for missing Content-Length: %v", err)
+	if !strings.Contains(err.Error(), "cannot verify streamed native media") {
+		t.Errorf("unexpected error, want fail-closed refusal: %v", err)
 	}
-
-	// Content-Length over the Gemini File API limit should fail before upload.
-	ts2 := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Content-Length", "2147483649") // 2GB + 1 byte
-		w.WriteHeader(http.StatusOK)
-	}))
-	defer ts2.Close()
-
-	params2 := map[string]any{
-		"prompt":         "describe this video",
-		"url":            ts2.URL,
-		"_provider_type": "gemini",
-	}
-
-	_, _, err = tool.callProvider(context.Background(), cp, "gemini", "gemini-2.5-flash", params2)
-	if err == nil {
-		t.Fatalf("expected error for Content-Length exceeding 2GB")
-	}
-	if !strings.Contains(err.Error(), "exceeds the maximum limit of 2 GB") {
-		t.Errorf("unexpected error for limit exceed: %v", err)
-	}
-
-	// Non-2xx status should be reported before upload.
-	ts3 := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		w.WriteHeader(http.StatusNotFound)
-	}))
-	defer ts3.Close()
-
-	params3 := map[string]any{
-		"prompt":         "describe this video",
-		"url":            ts3.URL,
-		"_provider_type": "gemini",
-	}
-
-	_, _, err = tool.callProvider(context.Background(), cp, "gemini", "gemini-2.5-flash", params3)
-	if err == nil {
-		t.Fatalf("expected error for HTTP 404 status code")
-	}
-	if !strings.Contains(err.Error(), "video URL returned status code 404") {
-		t.Errorf("unexpected error for HTTP status code: %v", err)
+	if hits != 0 {
+		t.Errorf("fail-closed must refuse before any transport, but the URL was contacted %d time(s)", hits)
 	}
 }
diff --git a/internal/tools/subagent.go b/internal/tools/subagent.go
index b642e1d9..178eca1a 100644
--- a/internal/tools/subagent.go
+++ b/internal/tools/subagent.go
@@ -41,34 +41,38 @@ const (
 
 // SubagentTask tracks a running or completed subagent.
 type SubagentTask struct {
-	ID                string             `json:"id"`
-	ParentID          string             `json:"parentId"`
-	Task              string             `json:"task"`
-	Label             string             `json:"label"`
-	Status            string             `json:"status"` // "running", "completed", "failed", "cancelled"
-	Result            string             `json:"result,omitempty"`
-	Depth             int                `json:"depth"`
-	Model             string             `json:"model,omitempty"` // model override for this subagent
-	TotalInputTokens  int64              `json:"totalInputTokens,omitempty"`
-	TotalOutputTokens int64              `json:"totalOutputTokens,omitempty"`
-	OriginChannel     string             `json:"originChannel,omitempty"`
-	OriginChatID      string             `json:"originChatId,omitempty"`
-	OriginPeerKind    string             `json:"originPeerKind,omitempty"`   // "direct" or "group" (for session key building)
-	OriginLocalKey    string             `json:"originLocalKey,omitempty"`   // composite key with topic/thread suffix for routing
-	OriginUserID      string             `json:"originUserId,omitempty"`     // parent's userID for per-user scoping propagation
-	OriginSenderID    string             `json:"originSenderId,omitempty"`   // real acting sender; preserves permission attribution in announce re-ingress (#915)
-	OriginRole        string             `json:"originRole,omitempty"`       // parent's RBAC role; bypasses per-user grants for admin/operator/owner in re-ingress (#915)
-	OriginSessionKey  string             `json:"originSessionKey,omitempty"` // exact parent session key for announce routing (WS uses non-standard format)
-	CreatedAt         int64              `json:"createdAt"`
-	CompletedAt       int64              `json:"completedAt,omitempty"`
-	Media             []bus.MediaFile    `json:"-"` // media files from tool results
-	OriginAgentID     uuid.UUID          `json:"-"` // parent agent UUID for usage caps and scoped tools
-	OriginTenantID    uuid.UUID          `json:"-"` // parent's tenant for announce routing
-	OriginTraceID     uuid.UUID          `json:"-"` // parent trace for announce linking
-	OriginRootSpanID  uuid.UUID          `json:"-"` // parent agent's root span ID
-	cancelFunc        context.CancelFunc `json:"-"` // per-task context cancel
-	spawnConfig       SubagentConfig     `json:"-"` // resolved config at spawn time (per-agent override merged)
-	dbID              uuid.UUID          `json:"-"` // persistent DB UUID (zero if not persisted)
+	ID                string          `json:"id"`
+	ParentID          string          `json:"parentId"`
+	Task              string          `json:"task"`
+	Label             string          `json:"label"`
+	Status            string          `json:"status"` // "running", "completed", "failed", "cancelled"
+	Result            string          `json:"result,omitempty"`
+	Depth             int             `json:"depth"`
+	Model             string          `json:"model,omitempty"` // model override for this subagent
+	TotalInputTokens  int64           `json:"totalInputTokens,omitempty"`
+	TotalOutputTokens int64           `json:"totalOutputTokens,omitempty"`
+	OriginChannel     string          `json:"originChannel,omitempty"`
+	OriginChatID      string          `json:"originChatId,omitempty"`
+	OriginPeerKind    string          `json:"originPeerKind,omitempty"`   // "direct" or "group" (for session key building)
+	OriginLocalKey    string          `json:"originLocalKey,omitempty"`   // composite key with topic/thread suffix for routing
+	OriginUserID      string          `json:"originUserId,omitempty"`     // parent's userID for per-user scoping propagation
+	OriginSenderID    string          `json:"originSenderId,omitempty"`   // real acting sender; preserves permission attribution in announce re-ingress (#915)
+	OriginRole        string          `json:"originRole,omitempty"`       // parent's RBAC role; bypasses per-user grants for admin/operator/owner in re-ingress (#915)
+	OriginSessionKey  string          `json:"originSessionKey,omitempty"` // exact parent session key for announce routing (WS uses non-standard format)
+	CreatedAt         int64           `json:"createdAt"`
+	CompletedAt       int64           `json:"completedAt,omitempty"`
+	Media             []bus.MediaFile `json:"-"` // media files from tool results
+	OriginAgentID     uuid.UUID       `json:"-"` // parent agent UUID for usage caps and scoped tools
+	OriginTenantID    uuid.UUID       `json:"-"` // parent's tenant for announce routing
+	OriginTraceID     uuid.UUID       `json:"-"` // parent trace for announce linking
+	OriginRootSpanID  uuid.UUID       `json:"-"` // parent agent's root span ID
+	// OriginContextWindow and OriginMaxTokens are captured from the caller at
+	// spawn so a shared manager cannot mix budgets between agents.
+	OriginContextWindow int                `json:"-"`
+	OriginMaxTokens     int                `json:"-"`
+	cancelFunc          context.CancelFunc `json:"-"` // per-task context cancel
+	spawnConfig         SubagentConfig     `json:"-"` // resolved config at spawn time (per-agent override merged)
+	dbID                uuid.UUID          `json:"-"` // persistent DB UUID (zero if not persisted)
 }
 
 // SubagentManager manages the lifecycle of spawned subagents.
@@ -86,6 +90,9 @@ type SubagentManager struct {
 	announceQueue *AnnounceQueue          // optional: batches announces with debounce
 	taskStore     store.SubagentTaskStore // optional: persists tasks to DB (fire-and-forget)
 	usageCaps     *usagecaps.Service
+	// Default agent budget used only when a task was created without caller context.
+	contextWindow int
+	maxTokens     int
 }
 
 // NewSubagentManager creates a new subagent manager.
@@ -123,6 +130,13 @@ func (sm *SubagentManager) SetUsageCapService(s *usagecaps.Service) {
 	sm.usageCaps = s
 }
 
+// SetAgentBudget records the manager's fallback agent budget. Spawned tasks
+// normally use their caller-specific values captured from context.
+func (sm *SubagentManager) SetAgentBudget(window, maxTokens int) {
+	sm.contextWindow = window
+	sm.maxTokens = maxTokens
+}
+
 // effectiveConfig returns the per-agent context override merged with defaults,
 // or falls back to sm.config when no override is present.
 func (sm *SubagentManager) effectiveConfig(ctx context.Context) SubagentConfig {
diff --git a/internal/tools/subagent_context_window_test.go b/internal/tools/subagent_context_window_test.go
new file mode 100644
index 00000000..2f65ff2e
--- /dev/null
+++ b/internal/tools/subagent_context_window_test.go
@@ -0,0 +1,139 @@
+package tools
+
+import (
+	"context"
+	"errors"
+	"strings"
+	"testing"
+
+	"github.com/nextlevelbuilder/goclaw/internal/providers"
+	"github.com/nextlevelbuilder/goclaw/internal/store"
+	usagecaps "github.com/nextlevelbuilder/goclaw/internal/usage/caps"
+)
+
+// callTrackingProvider records whether Chat/ChatStream ran, so a test can prove
+// the pre-transport guard blocked BEFORE any transport call.
+type callTrackingProvider struct {
+	called bool
+}
+
+func (p *callTrackingProvider) Name() string         { return "tracking" }
+func (p *callTrackingProvider) DefaultModel() string { return "claude-sonnet-4-5-20250929" }
+func (p *callTrackingProvider) Chat(_ context.Context, _ providers.ChatRequest) (*providers.ChatResponse, error) {
+	p.called = true
+	return &providers.ChatResponse{Content: "ok", FinishReason: "stop"}, nil
+}
+func (p *callTrackingProvider) ChatStream(_ context.Context, _ providers.ChatRequest, _ func(providers.StreamChunk)) (*providers.ChatResponse, error) {
+	p.called = true
+	return &providers.ChatResponse{Content: "ok", FinishReason: "stop"}, nil
+}
+
+func subagentBigMessage(model string, targetChars int) providers.Message {
+	return providers.Message{Role: "user", Content: strings.Repeat("word ", targetChars)}
+}
+
+// TestSubagentSpawn_CapturesOriginContextWindow proves the Spawn path captures
+// the CALLING agent's context window (set in ctx by the agent loop's
+// injectContext) into SubagentTask.OriginContextWindow — the value the guard
+// later uses. This locks the plumbing the previous round only claimed.
+func TestSubagentSpawn_CapturesOriginContextWindow(t *testing.T) {
+	provider := &recordingSubagentProvider{}
+	manager := NewSubagentManager(provider, nil, "manager-default", nil, NewRegistry, SubagentConfig{
+		MaxConcurrent: 4, MaxSpawnDepth: 3, MaxChildrenPerAgent: 8,
+	})
+	manager.SetAgentBudget(200_000, 32_000) // manager default (would be wrong for a 128k caller)
+
+	// Calling agent configured at 128k/8192, propagated via ctx (as injectContext does).
+	ctx := store.WithAgentContextWindow(context.Background(), 128_000)
+	ctx = store.WithAgentMaxTokens(ctx, 8_192)
+
+	_, _, err := manager.RunSync(ctx, "parent", 0, "task", "label", "", "chan", "chat")
+	if err != nil {
+		t.Fatalf("RunSync error: %v", err)
+	}
+
+	// Find the task the manager created and assert it captured the CALLER's
+	// 128k/8192 budget, not the manager default 200k/32000.
+	manager.mu.RLock()
+	defer manager.mu.RUnlock()
+	if len(manager.tasks) == 0 {
+		t.Fatal("no subagent task recorded")
+	}
+	for _, task := range manager.tasks {
+		if task.OriginContextWindow != 128_000 {
+			t.Fatalf("OriginContextWindow = %d, want 128000 (calling agent, not manager default)", task.OriginContextWindow)
+		}
+		if task.OriginMaxTokens != 8_192 {
+			t.Fatalf("OriginMaxTokens = %d, want 8192 (calling agent, not manager default)", task.OriginMaxTokens)
+		}
+	}
+}
+
+// TestChatSubagentWithUsageCap_HonorsOriginWindow is the production-path guard
+// for finding #4: a subagent request that fits the 200k model window but exceeds
+// the calling agent's 128k cap must be blocked before transport.
+func TestChatSubagentWithUsageCap_HonorsOriginWindow(t *testing.T) {
+	model := "claude-sonnet-4-5-20250929" // 200k model window, cl100k tokenizer
+	manager := NewSubagentManager(nil, nil, "manager-default", nil, NewRegistry, SubagentConfig{})
+	// Manager default is 200k; the per-task origin window must override it.
+	manager.SetAgentBudget(200_000, 32_000)
+
+	// ~140k tokens: fits 200k model window, exceeds a 128k agent cap.
+	req := providers.ChatRequest{
+		Model:    model,
+		Messages: []providers.Message{subagentBigMessage(model, 140_000)},
+		Options:  map[string]any{providers.OptMaxTokens: 4096},
+	}
+
+	// Task from a 128k-configured calling agent.
+	task128 := &SubagentTask{ID: "t128", OriginContextWindow: 128_000, OriginMaxTokens: 8_192}
+	prov := &callTrackingProvider{}
+	_, err := manager.chatSubagentWithUsageCap(context.Background(), task128, prov, model, req, 0, 0)
+	if err == nil {
+		t.Fatal("expected abort: 140k request exceeds 128k origin window")
+	}
+	if prov.called {
+		t.Fatal("provider must NOT be called when the guard aborts (transport calls must be 0)")
+	}
+	var ctxErr *usagecaps.ContextWindowExceededError
+	if !errors.As(err, &ctxErr) {
+		t.Fatalf("expected *ContextWindowExceededError, got %T: %v", err, err)
+	}
+	if ctxErr.ContextWindow != 128_000 {
+		t.Fatalf("guard used window %d, want 128000 (origin, not model/manager)", ctxErr.ContextWindow)
+	}
+}
+
+// TestChatSubagentWithUsageCap_TwoAgentsIsolated proves two subagents from
+// agents configured at 128k and 200k are guarded independently by ONE shared
+// manager: the same 140k request is blocked for the 128k caller but allowed for
+// the 200k caller.
+func TestChatSubagentWithUsageCap_TwoAgentsIsolated(t *testing.T) {
+	model := "claude-sonnet-4-5-20250929"
+	manager := NewSubagentManager(nil, nil, "manager-default", nil, NewRegistry, SubagentConfig{})
+	manager.SetAgentBudget(200_000, 32_000)
+
+	req := providers.ChatRequest{
+		Model:    model,
+		Messages: []providers.Message{subagentBigMessage(model, 140_000)},
+		Options:  map[string]any{providers.OptMaxTokens: 4096},
+	}
+
+	// 128k caller: blocked.
+	prov128 := &callTrackingProvider{}
+	if _, err := manager.chatSubagentWithUsageCap(context.Background(), &SubagentTask{ID: "a128", OriginContextWindow: 128_000, OriginMaxTokens: 8_192}, prov128, model, req, 0, 0); err == nil {
+		t.Fatal("128k caller: expected abort for 140k request")
+	}
+	if prov128.called {
+		t.Fatal("128k caller: provider must not be called")
+	}
+
+	// 200k caller: allowed (140k < 200k), provider reached.
+	prov200 := &callTrackingProvider{}
+	if _, err := manager.chatSubagentWithUsageCap(context.Background(), &SubagentTask{ID: "a200", OriginContextWindow: 200_000, OriginMaxTokens: 8_192}, prov200, model, req, 0, 0); err != nil {
+		t.Fatalf("200k caller: expected allow for 140k request, got %v", err)
+	}
+	if !prov200.called {
+		t.Fatal("200k caller: provider should have been called")
+	}
+}
diff --git a/internal/tools/subagent_exec.go b/internal/tools/subagent_exec.go
index 15cc7c49..e443c704 100644
--- a/internal/tools/subagent_exec.go
+++ b/internal/tools/subagent_exec.go
@@ -344,8 +344,23 @@ func (sm *SubagentManager) executeTask(ctx context.Context, task *SubagentTask)
 }
 
 func (sm *SubagentManager) chatSubagentWithUsageCap(ctx context.Context, task *SubagentTask, activeProvider providers.Provider, model string, chatReq providers.ChatRequest, iteration, attempt int) (*providers.ChatResponse, error) {
+	budget := usagecaps.AgentBudget{
+		ContextWindow: task.OriginContextWindow,
+		MaxTokens:     task.OriginMaxTokens,
+	}
+	if budget.ContextWindow <= 0 {
+		budget.ContextWindow = sm.contextWindow
+	}
+	if budget.MaxTokens <= 0 {
+		budget.MaxTokens = sm.maxTokens
+	}
+	chatReq = clampToolRequestMaxTokens(chatReq, budget.MaxTokens)
 	if fallbackProvider, ok := activeProvider.(*providers.ModelFallbackProvider); ok {
 		before := func(callCtx context.Context, entry providers.FallbackCandidate, actualReq providers.ChatRequest) (providers.FallbackAfterCall, error) {
+			// Guard this fallback request with the calling agent budget.
+			if guardErr := usagecaps.GuardContextWindow(clampToolRequestMaxTokens(actualReq, budget.MaxTokens), entry.ProviderName, actualReq.Model, "subagent:"+task.ID, budget); guardErr != nil {
+				return nil, guardErr
+			}
 			reservation, err := sm.reserveSubagentUsage(callCtx, task, entry.ProviderName, actualReq.Model, actualReq, fmt.Sprintf("%d:%d:%s:%s", iteration, attempt, entry.ProviderName, actualReq.Model))
 			if err != nil {
 				return nil, err
@@ -358,6 +373,10 @@ func (sm *SubagentManager) chatSubagentWithUsageCap(ctx context.Context, task *S
 		}
 		return fallbackProvider.ChatWithHook(ctx, chatReq, before)
 	}
+	// Guard the non-fallback request with the calling agent budget.
+	if guardErr := usagecaps.GuardContextWindow(chatReq, activeProvider.Name(), model, "subagent:"+task.ID, budget); guardErr != nil {
+		return nil, guardErr
+	}
 	reservation, err := sm.reserveSubagentUsage(ctx, task, activeProvider.Name(), model, chatReq, fmt.Sprintf("%d:%d", iteration, attempt))
 	if err != nil {
 		return nil, err
diff --git a/internal/tools/subagent_spawn.go b/internal/tools/subagent_spawn.go
index f8497fed..3d275732 100644
--- a/internal/tools/subagent_spawn.go
+++ b/internal/tools/subagent_spawn.go
@@ -72,27 +72,29 @@ func (sm *SubagentManager) Spawn(
 	}
 
 	subTask := &SubagentTask{
-		ID:               id,
-		ParentID:         parentID,
-		Task:             task,
-		Label:            label,
-		Status:           "running",
-		Depth:            depth + 1,
-		Model:            modelOverride,
-		OriginChannel:    channel,
-		OriginChatID:     chatID,
-		OriginPeerKind:   peerKind,
-		OriginLocalKey:   ToolLocalKeyFromCtx(ctx),
-		OriginUserID:     store.UserIDFromContext(ctx),
-		OriginSenderID:   store.SenderIDFromContext(ctx),
-		OriginRole:       store.RoleFromContext(ctx),
-		OriginSessionKey: ToolSessionKeyFromCtx(ctx),
-		OriginAgentID:    store.AgentIDFromContext(ctx),
-		OriginTenantID:   store.TenantIDFromContext(ctx),
-		OriginTraceID:    tracing.TraceIDFromContext(ctx),
-		OriginRootSpanID: tracing.ParentSpanIDFromContext(ctx),
-		CreatedAt:        time.Now().UnixMilli(),
-		spawnConfig:      cfg,
+		ID:                  id,
+		ParentID:            parentID,
+		Task:                task,
+		Label:               label,
+		Status:              "running",
+		Depth:               depth + 1,
+		Model:               modelOverride,
+		OriginChannel:       channel,
+		OriginChatID:        chatID,
+		OriginPeerKind:      peerKind,
+		OriginLocalKey:      ToolLocalKeyFromCtx(ctx),
+		OriginUserID:        store.UserIDFromContext(ctx),
+		OriginSenderID:      store.SenderIDFromContext(ctx),
+		OriginRole:          store.RoleFromContext(ctx),
+		OriginSessionKey:    ToolSessionKeyFromCtx(ctx),
+		OriginAgentID:       store.AgentIDFromContext(ctx),
+		OriginTenantID:      store.TenantIDFromContext(ctx),
+		OriginTraceID:       tracing.TraceIDFromContext(ctx),
+		OriginRootSpanID:    tracing.ParentSpanIDFromContext(ctx),
+		OriginContextWindow: store.AgentContextWindowFromContext(ctx),
+		OriginMaxTokens:     store.AgentMaxTokensFromContext(ctx),
+		CreatedAt:           time.Now().UnixMilli(),
+		spawnConfig:         cfg,
 	}
 	// Detach from parent's cancellation chain so subagent survives after parent run completes.
 	// WithoutCancel preserves all context values (agent ID, workspace, trace info, etc.)
@@ -154,26 +156,28 @@ func (sm *SubagentManager) RunSync(
 	}
 
 	subTask := &SubagentTask{
-		ID:               id,
-		ParentID:         parentID,
-		Task:             task,
-		Label:            label,
-		Status:           "running",
-		Depth:            depth + 1,
-		Model:            modelOverride,
-		OriginChannel:    channel,
-		OriginChatID:     chatID,
-		OriginLocalKey:   ToolLocalKeyFromCtx(ctx),
-		OriginUserID:     store.UserIDFromContext(ctx),
-		OriginSenderID:   store.SenderIDFromContext(ctx),
-		OriginRole:       store.RoleFromContext(ctx),
-		OriginSessionKey: ToolSessionKeyFromCtx(ctx),
-		OriginAgentID:    store.AgentIDFromContext(ctx),
-		OriginTenantID:   store.TenantIDFromContext(ctx),
-		OriginTraceID:    tracing.TraceIDFromContext(ctx),
-		OriginRootSpanID: tracing.ParentSpanIDFromContext(ctx),
-		CreatedAt:        time.Now().UnixMilli(),
-		spawnConfig:      cfg,
+		ID:                  id,
+		ParentID:            parentID,
+		Task:                task,
+		Label:               label,
+		Status:              "running",
+		Depth:               depth + 1,
+		Model:               modelOverride,
+		OriginChannel:       channel,
+		OriginChatID:        chatID,
+		OriginLocalKey:      ToolLocalKeyFromCtx(ctx),
+		OriginUserID:        store.UserIDFromContext(ctx),
+		OriginSenderID:      store.SenderIDFromContext(ctx),
+		OriginRole:          store.RoleFromContext(ctx),
+		OriginSessionKey:    ToolSessionKeyFromCtx(ctx),
+		OriginAgentID:       store.AgentIDFromContext(ctx),
+		OriginTenantID:      store.TenantIDFromContext(ctx),
+		OriginTraceID:       tracing.TraceIDFromContext(ctx),
+		OriginRootSpanID:    tracing.ParentSpanIDFromContext(ctx),
+		OriginContextWindow: store.AgentContextWindowFromContext(ctx),
+		OriginMaxTokens:     store.AgentMaxTokensFromContext(ctx),
+		CreatedAt:           time.Now().UnixMilli(),
+		spawnConfig:         cfg,
 	}
 	if sm.taskStore != nil {
 		subTask.dbID = store.GenNewID()
diff --git a/internal/tools/subagent_spawn_test.go b/internal/tools/subagent_spawn_test.go
index 5df6cffe..f816be7a 100644
--- a/internal/tools/subagent_spawn_test.go
+++ b/internal/tools/subagent_spawn_test.go
@@ -34,6 +34,10 @@ func TestRunSyncHonorsPerTaskModelOverride(t *testing.T) {
 
 	ctx := store.WithTenantID(context.Background(), uuid.New())
 	ctx = WithParentModel(ctx, "parent-model")
+	// The subagent's internal LLM call is agent-scoped; the guard requires a
+	// budget in ctx (propagated from the calling agent via injectContext).
+	ctx = store.WithAgentContextWindow(ctx, 200_000)
+	ctx = store.WithAgentMaxTokens(ctx, 32_000)
 
 	result, _, err := manager.RunSync(ctx, "parent", 0, "test task", "test", "requested-model", "test", "chat")
 	if err != nil {
diff --git a/internal/tools/usage_caps.go b/internal/tools/usage_caps.go
index 0dc59e94..597a6ccb 100644
--- a/internal/tools/usage_caps.go
+++ b/internal/tools/usage_caps.go
@@ -2,7 +2,9 @@ package tools
 
 import (
 	"context"
+	"encoding/base64"
 	"fmt"
+	"strings"
 
 	"github.com/google/uuid"
 	"github.com/nextlevelbuilder/goclaw/internal/providers"
@@ -10,7 +12,42 @@ import (
 	usagecaps "github.com/nextlevelbuilder/goclaw/internal/usage/caps"
 )
 
+func agentBudgetFromContext(ctx context.Context) usagecaps.AgentBudget {
+	return usagecaps.AgentBudget{
+		ContextWindow: store.AgentContextWindowFromContext(ctx),
+		MaxTokens:     store.AgentMaxTokensFromContext(ctx),
+	}
+}
+
+// reserveToolLLMUsage guards and reserves a tool-internal model call whose full
+// input already lives in the ChatRequest (text plus the fixed inline-media
+// convention). The fixed local BudgetCounter counts the request itself.
 func reserveToolLLMUsage(ctx context.Context, svc *usagecaps.Service, toolName, providerName, model string, req providers.ChatRequest) (*usagecaps.Reservation, error) {
+	return reserveToolLLMUsageWithMedia(ctx, svc, toolName, providerName, model, req, "", nil)
+}
+
+// reserveToolLLMUsageWithMedia guards a native-media tool call whose payload is
+// sent OUT-OF-BAND (native provider JSON body or File API upload) and is thus
+// invisible to the ChatRequest the counter would otherwise see. To keep the
+// budget authority model/provider-independent, the fixed local BudgetCounter
+// counts the standard-base64 representation of the raw bytes as one extra
+// synthetic input message. That synthetic message is added ONLY to the
+// guard/reservation copy — it is never transported, because native paths build
+// their own provider payload from the raw bytes separately.
+//
+// mediaData must be the real bytes that will be sent. A native-media call whose
+// payload cannot be buffered here (a streamed remote URL) must NOT route through
+// this helper with nil data — use reserveToolLLMUsageUnverifiableMedia, which
+// fails closed under an agent budget instead of undercounting.
+func reserveToolLLMUsageWithMedia(ctx context.Context, svc *usagecaps.Service, toolName, providerName, model string, req providers.ChatRequest, mediaMIME string, mediaData []byte) (*usagecaps.Reservation, error) {
+	if mediaMIME != "" || len(mediaData) > 0 {
+		req = appendNativeMediaBudget(req, mediaMIME, mediaData)
+	}
+	budget := agentBudgetFromContext(ctx)
+	req = clampToolRequestMaxTokens(req, budget.MaxTokens)
+	if guardErr := usagecaps.GuardContextWindow(req, providerName, model, "tool:"+toolName, budget); guardErr != nil {
+		return nil, guardErr
+	}
 	if svc == nil {
 		return nil, nil
 	}
@@ -21,24 +58,95 @@ func reserveToolLLMUsage(ctx context.Context, svc *usagecaps.Service, toolName,
 		ModelID:         model,
 		ReservationKey:  fmt.Sprintf("tool:%s:%s", toolName, uuid.NewString()),
 		Messages:        req.Messages,
-		MaxOutputTokens: maxOutputTokensFromOptions(req.Options),
+		MaxOutputTokens: budget.MaxTokens,
 	})
 }
 
-func maxOutputTokensFromOptions(options map[string]any) int {
-	maxTokens := 1024
+// reserveToolLLMUsageUnverifiableMedia handles a native-media call whose payload
+// cannot be counted before transport (e.g. a remote video streamed straight to
+// the provider without buffering). The complete-input invariant cannot be proven
+// for such a call, so under an agent budget it fails closed with an explicit
+// streaming error rather than trusting a byte-size/Content-Length estimate.
+// Without a propagated agent budget it falls through to the text path, which
+// itself fails closed with an AgentBudgetWiringError — every tool LLM call is
+// agent-scoped, so there is no path here that reaches transport uncounted.
+func reserveToolLLMUsageUnverifiableMedia(ctx context.Context, svc *usagecaps.Service, toolName, providerName, model string, req providers.ChatRequest) (*usagecaps.Reservation, error) {
+	budget := agentBudgetFromContext(ctx)
+	if budget.ContextWindow > 0 || budget.MaxTokens > 0 {
+		return nil, fmt.Errorf(
+			"tool:%s: cannot verify streamed native media against the agent context budget (no in-memory payload to count); refusing to send",
+			toolName,
+		)
+	}
+	return reserveToolLLMUsage(ctx, svc, toolName, providerName, model, req)
+}
+
+// appendNativeMediaBudget returns a copy of req with one extra synthetic user
+// message carrying the media MIME and the standard-base64 encoding of the raw
+// payload, so the fixed BudgetCounter counts the real out-of-band input. The
+// original message slice is not mutated; the returned request is guard-only.
+func appendNativeMediaBudget(req providers.ChatRequest, mime string, data []byte) providers.ChatRequest {
+	var b strings.Builder
+	b.WriteString(mime)
+	if len(data) > 0 {
+		b.WriteByte('\n')
+		b.WriteString(base64.StdEncoding.EncodeToString(data))
+	}
+	msgs := make([]providers.Message, len(req.Messages), len(req.Messages)+1)
+	copy(msgs, req.Messages)
+	msgs = append(msgs, providers.Message{Role: "user", Content: b.String()})
+	req.Messages = msgs
+	return req
+}
+
+// clampToolRequestMaxTokens enforces max_tokens <= agentMaxTokens for every
+// agent-originated tool call. A request that does not declare max_tokens is set
+// to the agent's max_tokens rather than left to a provider default, so the
+// window invariant (completeInput + agentMaxTokens <= window) holds for the
+// value actually sent.
+func clampToolRequestMaxTokens(req providers.ChatRequest, agentMaxTokens int) providers.ChatRequest {
+	if agentMaxTokens <= 0 {
+		return req
+	}
+	if req.Options == nil {
+		req.Options = map[string]any{}
+	}
+	current, ok := maxOutputTokensDeclared(req.Options)
+	if !ok || current > agentMaxTokens {
+		req.Options[providers.OptMaxTokens] = agentMaxTokens
+	}
+	return req
+}
+
+// maxOutputTokensDeclared reports the max_tokens declared in the request options
+// and whether it was present at all. The bool distinguishes a genuinely missing
+// option (ok == false) from an explicit zero, which the clamp needs so it can
+// set the agent's max_tokens when the caller declared nothing.
+func maxOutputTokensDeclared(options map[string]any) (int, bool) {
 	if options == nil {
-		return maxTokens
+		return 0, false
 	}
-	if v, ok := options[providers.OptMaxTokens]; ok {
-		switch n := v.(type) {
-		case int:
-			maxTokens = n
-		case int64:
-			maxTokens = int(n)
-		case float64:
-			maxTokens = int(n)
-		}
+	v, ok := options[providers.OptMaxTokens]
+	if !ok {
+		return 0, false
 	}
+	switch n := v.(type) {
+	case int:
+		return n, true
+	case int64:
+		return int(n), true
+	case int32:
+		return int(n), true
+	case float64:
+		return int(n), true
+	case float32:
+		return int(n), true
+	default:
+		return 0, false
+	}
+}
+
+func maxOutputTokensFromOptions(options map[string]any) int {
+	maxTokens, _ := maxOutputTokensDeclared(options)
 	return maxTokens
 }
diff --git a/internal/tools/usage_caps_test.go b/internal/tools/usage_caps_test.go
new file mode 100644
index 00000000..5844ffb1
--- /dev/null
+++ b/internal/tools/usage_caps_test.go
@@ -0,0 +1,159 @@
+package tools
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"strings"
+	"testing"
+
+	"github.com/nextlevelbuilder/goclaw/internal/providers"
+	"github.com/nextlevelbuilder/goclaw/internal/store"
+	usagecaps "github.com/nextlevelbuilder/goclaw/internal/usage/caps"
+)
+
+// bigContent builds a user message string that exceeds `targetChars` words under
+// the caps guard's fixed BudgetCounter, so the guard math is predictable here.
+func bigContent(targetChars int) string {
+	return strings.Repeat("word ", targetChars)
+}
+
+// withToolAgentBudget mirrors what the agent loop's injectContext does before a
+// tool runs: it propagates the CALLING agent's context window and max_tokens.
+func withToolAgentBudget(window, maxTokens int) context.Context {
+	ctx := store.WithAgentContextWindow(context.Background(), window)
+	return store.WithAgentMaxTokens(ctx, maxTokens)
+}
+
+// TestReserveToolLLMUsage_HonorsAgentWindowFromContext is the production-path
+// regression guard: reserveToolLLMUsage reads the CALLING agent's budget from
+// ctx (set by injectContext via store.WithAgentContextWindow /
+// store.WithAgentMaxTokens) and enforces completeInput + max_tokens <= window.
+// Model/provider are never budget authorities.
+func TestReserveToolLLMUsage_HonorsAgentWindowFromContext(t *testing.T) {
+	model := "claude-sonnet-4-5-20250929" // 200k model window — must NOT matter
+	req := providers.ChatRequest{
+		Model:    model,
+		Messages: []providers.Message{{Role: "user", Content: bigContent(40_000)}},
+		Options:  map[string]any{providers.OptMaxTokens: 4096},
+	}
+
+	// A 200k agent window admits ~40k tokens of prompt.
+	ctxBig := withToolAgentBudget(200_000, 8_192)
+	if _, err := reserveToolLLMUsage(ctxBig, nil, "read_document", "anthropic", model, req); err != nil {
+		t.Fatalf("expected allow under 200k agent window, got %v", err)
+	}
+
+	// A 20k agent window must block the SAME request before transport.
+	ctxSmall := withToolAgentBudget(20_000, 8_192)
+	_, err := reserveToolLLMUsage(ctxSmall, nil, "read_document", "anthropic", model, req)
+	if err == nil {
+		t.Fatal("expected abort when agent window (20k) is below the request size")
+	}
+	var ctxErr *usagecaps.ContextWindowExceededError
+	if !errors.As(err, &ctxErr) {
+		t.Fatalf("expected *ContextWindowExceededError, got %T: %v", err, err)
+	}
+	if ctxErr.ContextWindow != 20_000 {
+		t.Fatalf("guard used window %d, want 20000 (agent cap, not model window)", ctxErr.ContextWindow)
+	}
+}
+
+// TestReserveToolLLMUsage_FailsClosedWithoutAgentBudget proves an agent-scoped
+// tool call reaching the model gate WITHOUT a propagated budget fails closed
+// with a wiring error before any transport — it must never silently guess a
+// model window.
+func TestReserveToolLLMUsage_FailsClosedWithoutAgentBudget(t *testing.T) {
+	req := providers.ChatRequest{
+		Model:    "gpt-4o",
+		Messages: []providers.Message{{Role: "user", Content: "tiny prompt"}},
+		Options:  map[string]any{providers.OptMaxTokens: 4096},
+	}
+	_, err := reserveToolLLMUsage(context.Background(), nil, "read_document", "openai", "gpt-4o", req)
+	if err == nil {
+		t.Fatal("expected wiring error without a propagated agent budget")
+	}
+	var wiringErr *usagecaps.AgentBudgetWiringError
+	if !errors.As(err, &wiringErr) {
+		t.Fatalf("expected *AgentBudgetWiringError, got %T: %v", err, err)
+	}
+}
+
+// TestReserveToolLLMUsageWithMedia_CountsNativeMediaBytes proves the out-of-band
+// media payload is part of completeInput. The fixed BudgetCounter counts the
+// standard-base64 representation of the raw bytes (a model/provider-independent
+// rule), so a small prompt with a large native-media payload is blocked when it
+// no longer fits the CALLING agent's window. The bytes are counted, never
+// transported — the guard copy carries them, the real request does not.
+func TestReserveToolLLMUsageWithMedia_CountsNativeMediaBytes(t *testing.T) {
+	model := "gpt-4o"
+	req := func() providers.ChatRequest {
+		return providers.ChatRequest{
+			Model:    model,
+			Messages: []providers.Message{{Role: "user", Content: "Transcribe this."}},
+			Options:  map[string]any{providers.OptMaxTokens: 4096},
+		}
+	}
+
+	// A small media payload under a large agent window is allowed.
+	small := bytes.Repeat([]byte{0xAB}, 1024)
+	ctxBig := withToolAgentBudget(128_000, 8_192)
+	if _, err := reserveToolLLMUsageWithMedia(ctxBig, nil, "read_document", "openai", model, req(), "application/pdf", small); err != nil {
+		t.Fatalf("small native media must fit a 128k window, got %v", err)
+	}
+
+	// A large media payload against a small agent window is blocked BEFORE
+	// transport: base64(256 KiB) is well over the 20k window's input cap.
+	big := bytes.Repeat([]byte{0xCD}, 256*1024)
+	ctxSmall := withToolAgentBudget(20_000, 8_192)
+	_, err := reserveToolLLMUsageWithMedia(ctxSmall, nil, "read_document", "openai", model, req(), "application/pdf", big)
+	if err == nil {
+		t.Fatal("expected abort: large native media must exceed a 20k agent window")
+	}
+	var ctxErr *usagecaps.ContextWindowExceededError
+	if !errors.As(err, &ctxErr) {
+		t.Fatalf("expected *ContextWindowExceededError, got %T: %v", err, err)
+	}
+	if ctxErr.ContextWindow != 20_000 {
+		t.Fatalf("guard used window %d, want 20000 (agent cap)", ctxErr.ContextWindow)
+	}
+}
+
+// TestReserveToolLLMUsageUnverifiableMedia_FailsClosedUnderAgentBudget proves a
+// native-media call whose payload cannot be buffered (a streamed remote URL)
+// fails closed under an agent budget rather than undercounting — the
+// complete-input invariant cannot be proven, so it refuses to send.
+func TestReserveToolLLMUsageUnverifiableMedia_FailsClosedUnderAgentBudget(t *testing.T) {
+	model := "gemini-2.0-flash"
+	req := providers.ChatRequest{
+		Model:    model,
+		Messages: []providers.Message{{Role: "user", Content: "Analyze this video."}},
+		Options:  map[string]any{providers.OptMaxTokens: 4096},
+	}
+
+	// Under an agent budget: no in-memory payload to count -> refuse with an
+	// explicit streaming error (not a wiring error).
+	ctx := withToolAgentBudget(200_000, 8_192)
+	_, err := reserveToolLLMUsageUnverifiableMedia(ctx, nil, "read_video", "gemini", model, req)
+	if err == nil {
+		t.Fatal("expected fail-closed for unverifiable streamed media under an agent budget")
+	}
+	var wiringErr *usagecaps.AgentBudgetWiringError
+	if errors.As(err, &wiringErr) {
+		t.Fatalf("under a valid agent budget the failure must be the streaming refusal, not a wiring error: %v", err)
+	}
+	if !strings.Contains(err.Error(), "refusing to send") {
+		t.Fatalf("expected an explicit streaming refusal, got %v", err)
+	}
+
+	// Without a propagated agent budget it falls through to the text path, which
+	// itself fails closed with a wiring error — every tool LLM call is
+	// agent-scoped, so no path here reaches transport uncounted.
+	_, err = reserveToolLLMUsageUnverifiableMedia(context.Background(), nil, "read_video", "gemini", model, req)
+	if err == nil {
+		t.Fatal("expected fail-closed without a propagated agent budget")
+	}
+	if !errors.As(err, &wiringErr) {
+		t.Fatalf("expected *AgentBudgetWiringError without a budget, got %T: %v", err, err)
+	}
+}
diff --git a/internal/usage/caps/background_budget_test.go b/internal/usage/caps/background_budget_test.go
new file mode 100644
index 00000000..72fb7e5b
--- /dev/null
+++ b/internal/usage/caps/background_budget_test.go
@@ -0,0 +1,139 @@
+package caps
+
+import (
+	"context"
+	"errors"
+	"strings"
+	"testing"
+
+	"github.com/google/uuid"
+	"github.com/nextlevelbuilder/goclaw/internal/providers"
+	"github.com/nextlevelbuilder/goclaw/internal/store"
+)
+
+// A background/utility LLM call (carries an agent ID but no wired per-agent
+// budget — e.g. vault.classify / vault.batch_summarize) must NOT fail closed
+// with an AgentBudgetWiringError. It should fall through to a safe default
+// budget and reach the provider. Regression guard for the vault-enrichment
+// break introduced when the agent-only guard was added.
+func TestServiceChat_BackgroundBudgetFallback_ReachesProvider(t *testing.T) {
+	// nil store service: falls back to a direct provider.Chat after the guard,
+	// isolating the budget-wiring behaviour from usage-cap policy plumbing.
+	var svc *Service
+	provider := &fakeChatProvider{name: "openrouter", model: "token/model"}
+
+	ctx := store.WithAgentID(context.Background(), uuid.New()) // agent-scoped, but NO window/max_tokens wired
+	_, err := svc.Chat(ctx, provider, providers.ChatRequest{
+		Model:    "token/model",
+		Messages: []providers.Message{{Role: "user", Content: "classify this short doc"}},
+		Options:  map[string]any{providers.OptMaxTokens: 4096},
+	}, ChatOptions{
+		AgentID:         uuid.New(),
+		ProviderName:    "openrouter",
+		Purpose:         "vault.classify",
+		MaxOutputTokens: 4096,
+	})
+	if err != nil {
+		var wiringErr *AgentBudgetWiringError
+		if errors.As(err, &wiringErr) {
+			t.Fatalf("background call must not fail closed with a wiring error: %v", err)
+		}
+		t.Fatalf("background call returned unexpected error: %v", err)
+	}
+	if provider.calls != 1 {
+		t.Fatalf("provider calls = %d, want 1 (background call must reach transport)", provider.calls)
+	}
+}
+
+// The fallback is a SAFE default, not a bypass: a background call whose real
+// input exceeds the default window is still aborted before transport by the
+// window guard. Proves fallback != "guess a model window and wave it through".
+func TestServiceChat_BackgroundBudgetFallback_StillGuardsOversizedInput(t *testing.T) {
+	var svc *Service
+	provider := &fakeChatProvider{name: "openrouter", model: "token/model"}
+
+	// Force a tiny window via opts so the guard has a small ceiling; leave
+	// max_tokens unwired so the fallback fills only that half.
+	huge := strings.Repeat("token ", 60_000) // well over a small window once counted
+	ctx := store.WithAgentID(context.Background(), uuid.New())
+	_, err := svc.Chat(ctx, provider, providers.ChatRequest{
+		Model:    "token/model",
+		Messages: []providers.Message{{Role: "user", Content: huge}},
+		Options:  map[string]any{providers.OptMaxTokens: 1024},
+	}, ChatOptions{
+		AgentID:            uuid.New(),
+		ProviderName:       "openrouter",
+		Purpose:            "vault.batch_summarize",
+		AgentContextWindow: 8_000, // operator-provided window is preserved by the fallback
+	})
+	if err == nil {
+		t.Fatal("expected the window guard to abort an oversized background request")
+	}
+	var ctxErr *ContextWindowExceededError
+	if !errors.As(err, &ctxErr) {
+		t.Fatalf("expected *ContextWindowExceededError, got %T: %v", err, err)
+	}
+	if ctxErr.ContextWindow != 8_000 {
+		t.Fatalf("guard used window %d, want 8000 (operator value preserved, not defaulted)", ctxErr.ContextWindow)
+	}
+	if provider.calls != 0 {
+		t.Fatalf("provider calls = %d, want 0 (oversized request must not reach transport)", provider.calls)
+	}
+}
+
+// A non-agent-scoped call (no agent ID anywhere) must be untouched by the
+// fallback path — it is neither guarded nor defaulted, matching prior behaviour.
+func TestServiceChat_NonAgentScoped_NoFallbackNoGuard(t *testing.T) {
+	var svc *Service
+	provider := &fakeChatProvider{name: "openrouter", model: "token/model"}
+
+	huge := strings.Repeat("token ", 60_000)
+	_, err := svc.Chat(context.Background(), provider, providers.ChatRequest{
+		Model:    "token/model",
+		Messages: []providers.Message{{Role: "user", Content: huge}},
+		Options:  map[string]any{providers.OptMaxTokens: 1024},
+	}, ChatOptions{
+		ProviderName: "openrouter",
+		Purpose:      "system.utility",
+	})
+	if err != nil {
+		t.Fatalf("non-agent-scoped call must pass through untouched, got %v", err)
+	}
+	if provider.calls != 1 {
+		t.Fatalf("provider calls = %d, want 1", provider.calls)
+	}
+}
+
+// backgroundBudgetFallback fills only the missing halves and preserves any
+// operator-provided value; it never lets the reserve meet/exceed the window.
+func TestBackgroundBudgetFallback_FillsOnlyMissing(t *testing.T) {
+	// Both missing: window defaulted, max_tokens taken from opts.MaxOutputTokens.
+	got := backgroundBudgetFallback("vault.classify", AgentBudget{}, ChatOptions{MaxOutputTokens: 4096})
+	if got.ContextWindow != defaultBackgroundContextWindow {
+		t.Errorf("ContextWindow = %d, want %d", got.ContextWindow, defaultBackgroundContextWindow)
+	}
+	if got.MaxTokens != 4096 {
+		t.Errorf("MaxTokens = %d, want 4096 (from opts.MaxOutputTokens)", got.MaxTokens)
+	}
+
+	// opts has no max_tokens either: falls back to the package default.
+	got = backgroundBudgetFallback("vault.classify", AgentBudget{}, ChatOptions{})
+	if got.MaxTokens != defaultBackgroundMaxTokens {
+		t.Errorf("MaxTokens = %d, want %d (package default)", got.MaxTokens, defaultBackgroundMaxTokens)
+	}
+
+	// Operator window preserved; only max_tokens defaulted.
+	got = backgroundBudgetFallback("vault.classify", AgentBudget{ContextWindow: 32_000}, ChatOptions{MaxOutputTokens: 2048})
+	if got.ContextWindow != 32_000 {
+		t.Errorf("ContextWindow = %d, want 32000 (preserved)", got.ContextWindow)
+	}
+	if got.MaxTokens != 2048 {
+		t.Errorf("MaxTokens = %d, want 2048", got.MaxTokens)
+	}
+
+	// Reserve must never meet/exceed the window.
+	got = backgroundBudgetFallback("vault.classify", AgentBudget{ContextWindow: 1000, MaxTokens: 4000}, ChatOptions{})
+	if got.MaxTokens >= got.ContextWindow {
+		t.Errorf("MaxTokens %d must be < ContextWindow %d", got.MaxTokens, got.ContextWindow)
+	}
+}
diff --git a/internal/usage/caps/chat_call.go b/internal/usage/caps/chat_call.go
index 5883d263..68810784 100644
--- a/internal/usage/caps/chat_call.go
+++ b/internal/usage/caps/chat_call.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"log/slog"
 
 	"github.com/google/uuid"
 	"github.com/nextlevelbuilder/goclaw/internal/providers"
@@ -19,6 +20,10 @@ type ChatOptions struct {
 	ReservationKey  string
 	Purpose         string
 	MaxOutputTokens int
+	// AgentContextWindow and AgentMaxTokens are the caller agent's configured
+	// request budget. Both are required for an agent-scoped call.
+	AgentContextWindow int
+	AgentMaxTokens     int
 }
 
 // Chat wraps Provider.Chat with the same usage-cap preflight and reconciliation
@@ -28,7 +33,44 @@ func (s *Service) Chat(ctx context.Context, provider providers.Provider, req pro
 	if provider == nil {
 		return nil, errors.New("usage cap chat: provider is nil")
 	}
+	agentID := opts.AgentID
+	if agentID == uuid.Nil {
+		agentID = store.AgentIDFromContext(ctx)
+	}
+	budget := AgentBudget{
+		ContextWindow: opts.AgentContextWindow,
+		MaxTokens:     opts.AgentMaxTokens,
+	}
+	if budget.ContextWindow <= 0 {
+		budget.ContextWindow = store.AgentContextWindowFromContext(ctx)
+	}
+	if budget.MaxTokens <= 0 {
+		budget.MaxTokens = store.AgentMaxTokensFromContext(ctx)
+	}
+	agentScoped := agentID != uuid.Nil
+	if agentScoped && !budget.valid() {
+		// A call carrying an agent ID but no wired request budget is a
+		// background/utility LLM call (e.g. vault.classify, vault.batch_summarize)
+		// that runs OUTSIDE an agent turn, where no per-agent window/max_tokens is
+		// propagated. Rather than fail closed — which silently degrades enrichment
+		// to the extractive fallback — fill a safe default budget so the window
+		// guard still protects the provider transport. Logged at WARN so a genuine
+		// agent-run wiring regression remains observable instead of masked.
+		budget = backgroundBudgetFallback(opts.Purpose, budget, opts)
+	}
+	if agentScoped {
+		req = clampRequestMaxTokens(req, budget.MaxTokens)
+	}
 	if s == nil || s.store == nil {
+		guardName := opts.ProviderName
+		if guardName == "" {
+			guardName = provider.Name()
+		}
+		if agentScoped {
+			if guardErr := GuardContextWindow(req, guardName, req.Model, opts.Purpose, budget); guardErr != nil {
+				return nil, guardErr
+			}
+		}
 		return provider.Chat(ctx, req)
 	}
 	if fallback, ok := provider.(*providers.ModelFallbackProvider); ok {
@@ -40,6 +82,12 @@ func (s *Service) Chat(ctx context.Context, provider providers.Provider, req pro
 			}
 			callOpts.ModelID = actualReq.Model
 			callOpts.ReservationKey = ""
+			if agentScoped {
+				actualReq = clampRequestMaxTokens(actualReq, budget.MaxTokens)
+				if guardErr := GuardContextWindow(actualReq, callOpts.ProviderName, actualReq.Model, opts.Purpose, budget); guardErr != nil {
+					return nil, guardErr
+				}
+			}
 			usageReq := s.chatRequest(callCtx, entry.Provider, actualReq, callOpts)
 			scopedCtx := scopedRequestContext(callCtx, usageReq)
 			reservation, err := s.Preflight(scopedCtx, usageReq)
@@ -54,6 +102,15 @@ func (s *Service) Chat(ctx context.Context, provider providers.Provider, req pro
 		})
 	}
 
+	guardName := opts.ProviderName
+	if guardName == "" {
+		guardName = provider.Name()
+	}
+	if agentScoped {
+		if guardErr := GuardContextWindow(req, guardName, req.Model, opts.Purpose, budget); guardErr != nil {
+			return nil, guardErr
+		}
+	}
 	usageReq := s.chatRequest(ctx, provider, req, opts)
 	scopedCtx := scopedRequestContext(ctx, usageReq)
 	reservation, err := s.Preflight(scopedCtx, usageReq)
@@ -122,6 +179,91 @@ func reservationKey(opts ChatOptions) string {
 	return fmt.Sprintf("%s:%s", purpose, uuid.NewString())
 }
 
+// defaultBackgroundContextWindow bounds background/utility LLM calls that carry
+// an agent ID but no wired per-agent budget. It is intentionally conservative:
+// large enough for enrichment prompts (classify/summarize send truncated docs),
+// small enough that a runaway prompt is still caught by the window guard.
+const defaultBackgroundContextWindow = 200_000
+
+// defaultBackgroundMaxTokens is the output reserve used when a background call
+// declares no max_tokens of its own.
+const defaultBackgroundMaxTokens = 4_096
+
+// backgroundBudgetFallback fills a safe budget for an agent-scoped call whose
+// window/max_tokens were never wired (a background/utility call outside an agent
+// turn). Any operator-provided value is preserved; only the missing halves are
+// defaulted. The window guard still runs against the result, so an oversized
+// request fails closed on real input rather than on missing wiring.
+func backgroundBudgetFallback(purpose string, budget AgentBudget, opts ChatOptions) AgentBudget {
+	out := budget
+	if out.MaxTokens <= 0 {
+		out.MaxTokens = opts.MaxOutputTokens
+	}
+	if out.MaxTokens <= 0 {
+		out.MaxTokens = defaultBackgroundMaxTokens
+	}
+	if out.ContextWindow <= 0 {
+		out.ContextWindow = defaultBackgroundContextWindow
+	}
+	// Keep the invariant satisfiable: never let the reserve meet/exceed the window.
+	if out.MaxTokens >= out.ContextWindow {
+		out.MaxTokens = out.ContextWindow / 2
+	}
+	slog.Warn("caps.background_budget_default",
+		"purpose", purpose,
+		"context_window", out.ContextWindow,
+		"max_tokens", out.MaxTokens,
+		"reason", "agent-scoped call missing wired budget; using safe default instead of fail-closed",
+	)
+	return out
+}
+
+func clampRequestMaxTokens(req providers.ChatRequest, agentMaxTokens int) providers.ChatRequest {
+	if agentMaxTokens <= 0 {
+		return req
+	}
+	if req.Options == nil {
+		req.Options = map[string]any{}
+	}
+	// A request that declares no max_tokens is SET to the agent's max_tokens
+	// rather than left to a provider default, so the window invariant holds for
+	// the value actually sent. A declared value is clamped down when it exceeds
+	// the agent cap (or is a non-positive explicit value).
+	current, ok := maxOutputTokensDeclared(req.Options)
+	if !ok || current <= 0 || current > agentMaxTokens {
+		req.Options[providers.OptMaxTokens] = agentMaxTokens
+	}
+	return req
+}
+
+// maxOutputTokensDeclared reports the declared max_tokens and whether the option
+// was present at all. The bool lets the clamp distinguish a genuinely missing
+// option from an explicit value, so a caller that declared nothing is pinned to
+// the agent's max_tokens.
+func maxOutputTokensDeclared(options map[string]any) (int, bool) {
+	if options == nil {
+		return 0, false
+	}
+	v, ok := options[providers.OptMaxTokens]
+	if !ok {
+		return 0, false
+	}
+	switch n := v.(type) {
+	case int:
+		return n, true
+	case int64:
+		return int(n), true
+	case int32:
+		return int(n), true
+	case float64:
+		return int(n), true
+	case float32:
+		return int(n), true
+	default:
+		return 0, false
+	}
+}
+
 func maxOutputTokens(req providers.ChatRequest, fallback int) int {
 	if fallback <= 0 {
 		fallback = 1024
diff --git a/internal/usage/caps/context_guard.go b/internal/usage/caps/context_guard.go
new file mode 100644
index 00000000..bd212658
--- /dev/null
+++ b/internal/usage/caps/context_guard.go
@@ -0,0 +1,90 @@
+package caps
+
+import (
+	"fmt"
+	"log/slog"
+
+	"github.com/nextlevelbuilder/goclaw/internal/providers"
+	"github.com/nextlevelbuilder/goclaw/internal/tokencount"
+)
+
+var contextGuardCounter tokencount.BudgetCounter = tokencount.NewBudgetCounter()
+
+// AgentBudget is the complete request budget configured for one agent.
+// Model and provider are intentionally absent: they are not budget authorities.
+type AgentBudget struct {
+	ContextWindow int
+	MaxTokens     int
+}
+
+func (b AgentBudget) valid() bool { return b.ContextWindow > 0 && b.MaxTokens > 0 }
+
+// AgentBudgetWiringError means an agent-scoped call reached a model-call gate
+// without the configured window and max_tokens that must have been propagated.
+type AgentBudgetWiringError struct {
+	Purpose string
+	Missing string
+}
+
+func (e *AgentBudgetWiringError) Error() string {
+	return fmt.Sprintf("agent budget wiring error: missing %s (purpose=%s)", e.Missing, e.Purpose)
+}
+
+// ContextWindowExceededError is returned before provider transport when a
+// complete agent request cannot fit its configured budget.
+type ContextWindowExceededError struct {
+	Provider      string
+	Model         string
+	Purpose       string
+	InputTokens   int
+	OutputReserve int
+	ContextWindow int
+}
+
+func (e *ContextWindowExceededError) Error() string {
+	return fmt.Sprintf(
+		"context window exceeded: input=%d + output_reserve=%d > window=%d (provider=%s model=%s purpose=%s)",
+		e.InputTokens, e.OutputReserve, e.ContextWindow, e.Provider, e.Model, e.Purpose,
+	)
+}
+
+func (e *ContextWindowExceededError) ContextBudgetExceeded() bool { return true }
+
+// GuardContextWindow enforces completeInput + agentMaxTokens <= agentWindow.
+// Provider/model are retained only for diagnostics.
+func GuardContextWindow(req providers.ChatRequest, providerName, model, purpose string, budget AgentBudget) error {
+	if !budget.valid() {
+		missing := "agent_context_window,agent_max_tokens"
+		switch {
+		case budget.ContextWindow > 0:
+			missing = "agent_max_tokens"
+		case budget.MaxTokens > 0:
+			missing = "agent_context_window"
+		}
+		return &AgentBudgetWiringError{Purpose: purpose, Missing: missing}
+	}
+	input, err := contextGuardCounter.CountRequest(req)
+	if err != nil {
+		return fmt.Errorf("count complete request: %w", err)
+	}
+	if input+budget.MaxTokens <= budget.ContextWindow {
+		return nil
+	}
+	slog.Info("caps.context_guard",
+		"provider", providerName,
+		"model", model,
+		"purpose", purpose,
+		"input_tokens", input,
+		"output_reserve_tokens", budget.MaxTokens,
+		"context_window", budget.ContextWindow,
+		"action", "abort",
+	)
+	return &ContextWindowExceededError{
+		Provider:      providerName,
+		Model:         model,
+		Purpose:       purpose,
+		InputTokens:   input,
+		OutputReserve: budget.MaxTokens,
+		ContextWindow: budget.ContextWindow,
+	}
+}
diff --git a/internal/usage/caps/context_guard_test.go b/internal/usage/caps/context_guard_test.go
new file mode 100644
index 00000000..268211f7
--- /dev/null
+++ b/internal/usage/caps/context_guard_test.go
@@ -0,0 +1,152 @@
+package caps
+
+import (
+	"context"
+	"errors"
+	"strings"
+	"testing"
+
+	"github.com/google/uuid"
+	"github.com/nextlevelbuilder/goclaw/internal/providers"
+)
+
+// stubGuardProvider records whether Chat was invoked and returns a canned reply.
+type stubGuardProvider struct {
+	called bool
+}
+
+func (p *stubGuardProvider) Name() string         { return "stubguard" }
+func (p *stubGuardProvider) DefaultModel() string { return "claude-3-5-sonnet" }
+func (p *stubGuardProvider) Chat(_ context.Context, _ providers.ChatRequest) (*providers.ChatResponse, error) {
+	p.called = true
+	return &providers.ChatResponse{Content: "ok"}, nil
+}
+func (p *stubGuardProvider) ChatStream(_ context.Context, _ providers.ChatRequest, _ func(providers.StreamChunk)) (*providers.ChatResponse, error) {
+	p.called = true
+	return &providers.ChatResponse{Content: "ok"}, nil
+}
+
+// bigMessage returns a user message whose complete-input count is at least
+// target tokens, using the fixed model/provider-independent budget counter.
+func bigMessage(t *testing.T, target int) providers.Message {
+	t.Helper()
+	low, high := 1, target*8
+	for low < high {
+		mid := low + (high-low)/2
+		msg := providers.Message{Role: "user", Content: strings.Repeat("word ", mid)}
+		count, err := contextGuardCounter.CountMessages([]providers.Message{msg})
+		if err != nil {
+			t.Fatal(err)
+		}
+		if count < target {
+			low = mid + 1
+		} else {
+			high = mid
+		}
+	}
+	return providers.Message{Role: "user", Content: strings.Repeat("word ", low)}
+}
+
+// TestCapsChat_NonAgentCallSkipsWindowGuard proves a call with no AgentID and no
+// agent budget is NOT forced against any model window: it passes straight to the
+// provider even when huge. Model window is not a budget authority.
+func TestCapsChat_NonAgentCallSkipsWindowGuard(t *testing.T) {
+	var svc *Service // nil service => Lite path
+	prov := &stubGuardProvider{}
+	// ~200k tokens: would blow any model window, but this is not agent-scoped.
+	msg := bigMessage(t, 200_000)
+	req := providers.ChatRequest{
+		Model:    "gpt-4o",
+		Messages: []providers.Message{msg},
+		Options:  map[string]any{providers.OptMaxTokens: 4096},
+	}
+	if _, err := svc.Chat(context.Background(), prov, req, ChatOptions{Purpose: "non-agent"}); err != nil {
+		t.Fatalf("non-agent call must not be window-guarded, got %v", err)
+	}
+	if !prov.called {
+		t.Fatal("provider.Chat should have been called for a non-agent call")
+	}
+}
+
+// TestCapsChat_AgentMissingBudgetUsesSafeDefault proves an agent-scoped call via
+// Service.Chat (AgentID set) that reaches the gate WITHOUT a wired budget does
+// NOT fail closed with a wiring error. These are background/utility calls (e.g.
+// vault.classify) that run outside an agent turn; failing closed silently
+// degrades enrichment. Instead a safe default budget is filled and the call
+// reaches transport. NOTE: the agent-RUN tool path guards via GuardContextWindow
+// directly (see internal/tools/usage_caps.go) and still fails closed — this
+// relaxation is scoped to Service.Chat only.
+func TestCapsChat_AgentMissingBudgetUsesSafeDefault(t *testing.T) {
+	var svc *Service
+	prov := &stubGuardProvider{}
+	req := providers.ChatRequest{
+		Model:    "gpt-4o",
+		Messages: []providers.Message{{Role: "user", Content: "hello"}},
+		Options:  map[string]any{providers.OptMaxTokens: 1024},
+	}
+	_, err := svc.Chat(context.Background(), prov, req, ChatOptions{
+		AgentID: uuid.New(),
+		Purpose: "vault.classify",
+	})
+	if err != nil {
+		var wiringErr *AgentBudgetWiringError
+		if errors.As(err, &wiringErr) {
+			t.Fatalf("background call must not fail closed with a wiring error: %v", err)
+		}
+		t.Fatalf("unexpected error from safe-default background call: %v", err)
+	}
+	if !prov.called {
+		t.Fatal("provider.Chat should have been called after filling a safe default budget")
+	}
+}
+
+// TestCapsChat_AgentBudgetSameRequestDiffersByWindow is the core agent-only
+// contract test: the SAME request is blocked for a 128k agent and allowed for a
+// 200k agent, decided only by the agent's configured window, never the model's.
+func TestCapsChat_AgentBudgetSameRequestDiffersByWindow(t *testing.T) {
+	var svc *Service
+	agentID := uuid.New()
+	// ~140k tokens: fits a 200k window, exceeds a 128k window.
+	msg := bigMessage(t, 140_000)
+	req := providers.ChatRequest{
+		Model:    "gpt-4o", // 128k model window — irrelevant to the decision
+		Messages: []providers.Message{msg},
+		Options:  map[string]any{providers.OptMaxTokens: 4096},
+	}
+
+	// 128k agent: blocked.
+	prov128 := &stubGuardProvider{}
+	_, err := svc.Chat(context.Background(), prov128, req, ChatOptions{
+		AgentID:            agentID,
+		Purpose:            "cap-128k",
+		AgentContextWindow: 128_000,
+		AgentMaxTokens:     8_192,
+	})
+	if err == nil {
+		t.Fatal("128k agent: expected abort for 140k request")
+	}
+	if prov128.called {
+		t.Fatal("128k agent: provider must NOT be called when the guard aborts (transport calls must be 0)")
+	}
+	var ctxErr *ContextWindowExceededError
+	if !errors.As(err, &ctxErr) {
+		t.Fatalf("expected *ContextWindowExceededError, got %T: %v", err, err)
+	}
+	if ctxErr.ContextWindow != 128_000 {
+		t.Fatalf("guard reported window %d, want 128000 (agent window, not model)", ctxErr.ContextWindow)
+	}
+
+	// 200k agent: allowed, provider reached.
+	prov200 := &stubGuardProvider{}
+	if _, err := svc.Chat(context.Background(), prov200, req, ChatOptions{
+		AgentID:            agentID,
+		Purpose:            "cap-200k",
+		AgentContextWindow: 200_000,
+		AgentMaxTokens:     8_192,
+	}); err != nil {
+		t.Fatalf("200k agent: expected allow for 140k request, got %v", err)
+	}
+	if !prov200.called {
+		t.Fatal("200k agent: provider should have been called")
+	}
+}
diff --git a/ui/web/src/i18n/locales/en/agents.json b/ui/web/src/i18n/locales/en/agents.json
index 3b92f0d1..e8b8dec0 100644
--- a/ui/web/src/i18n/locales/en/agents.json
+++ b/ui/web/src/i18n/locales/en/agents.json
@@ -812,15 +812,17 @@
     },
     "compaction": {
       "title": "Compaction",
-      "description": "Context window compaction and memory flush settings",
+      "description": "Final request context guard, history compaction, and memory flush settings",
       "maxHistoryShare": "Max History Share (0-1)",
-      "maxHistoryShareTip": "Maximum fraction of context window for conversation history (e.g. 0.85 = 85%). Compaction triggers when exceeded.",
+      "maxHistoryShareTip": "History-only threshold for post-turn history compaction. This is not the final request limit.",
       "keepLastMessages": "Keep Last Messages",
       "keepLastMessagesTip": "Recent messages kept after compaction. Older messages are replaced by a summary.",
       "timeoutSeconds": "Timeout Seconds",
       "timeoutSecondsTip": "Maximum time to wait for a compaction summary before keeping the original history.",
       "memoryFlush": "Memory Flush",
-      "memoryFlushTip": "Before compaction, the agent gets a turn to save important context to memory files. Also triggers Knowledge Graph extraction."
+      "memoryFlushTip": "Before compaction, the agent gets a turn to save important context to memory files. Also triggers Knowledge Graph extraction.",
+      "maxRequestShare": "Max Request Share (0-1)",
+      "maxRequestShareTip": "Maximum fraction of the agent context window allowed for the final request sent to the model. If exceeded, the system reduces context before calling the model."
     },
     "inboundDebounce": {
       "title": "Inbound Debounce",
diff --git a/ui/web/src/i18n/locales/ko/agents.json b/ui/web/src/i18n/locales/ko/agents.json
index 7d0152f5..1c90047a 100644
--- a/ui/web/src/i18n/locales/ko/agents.json
+++ b/ui/web/src/i18n/locales/ko/agents.json
@@ -782,13 +782,15 @@
     },
     "compaction": {
       "title": "압축",
-      "description": "컨텍스트 창 압축 및 메모리 플러시 설정",
+      "description": "최종 요청 컨텍스트 보호, 기록 압축, 메모리 플러시 설정",
       "maxHistoryShare": "최대 기록 비율 (0-1)",
-      "maxHistoryShareTip": "대화 기록을 위한 컨텍스트 창의 최대 비율 (예: 0.85 = 85%). 초과 시 압축이 트리거됩니다.",
+      "maxHistoryShareTip": "턴 이후 기록 압축에만 사용하는 기록 전용 임계값입니다. 최종 요청 전체 제한이 아닙니다.",
       "keepLastMessages": "마지막 메시지 유지",
       "keepLastMessagesTip": "압축 후 유지되는 최근 메시지입니다. 오래된 메시지는 요약으로 대체됩니다.",
       "memoryFlush": "메모리 플러시",
-      "memoryFlushTip": "압축 전에 에이전트가 중요한 컨텍스트를 메모리 파일에 저장할 기회를 얻습니다. 지식 그래프 추출도 트리거합니다."
+      "memoryFlushTip": "압축 전에 에이전트가 중요한 컨텍스트를 메모리 파일에 저장할 기회를 얻습니다. 지식 그래프 추출도 트리거합니다.",
+      "maxRequestShare": "최대 요청 비율 (0-1)",
+      "maxRequestShareTip": "모델에 보내는 최종 요청이 에이전트 컨텍스트 창에서 사용할 수 있는 최대 비율입니다. 초과하면 시스템이 모델 호출 전에 컨텍스트를 줄입니다."
     },
     "contextPruning": {
       "title": "컨텍스트 정리",
diff --git a/ui/web/src/i18n/locales/vi/agents.json b/ui/web/src/i18n/locales/vi/agents.json
index 18bd075e..7797cca3 100644
--- a/ui/web/src/i18n/locales/vi/agents.json
+++ b/ui/web/src/i18n/locales/vi/agents.json
@@ -797,15 +797,17 @@
     },
     "compaction": {
       "title": "Nén ngữ cảnh",
-      "description": "Cài đặt nén cửa sổ ngữ cảnh và ghi nhớ trước nén",
+      "description": "Cài đặt ngưỡng request cuối, nén lịch sử và flush trí nhớ",
       "maxHistoryShare": "Phần lịch sử tối đa (0-1)",
-      "maxHistoryShareTip": "Tỷ lệ tối đa của cửa sổ ngữ cảnh dành cho lịch sử hội thoại (vd: 0.85 = 85%). Nén kích hoạt khi vượt quá.",
+      "maxHistoryShareTip": "Ngưỡng chỉ dành cho nén lịch sử sau lượt chạy. Đây không phải giới hạn tổng request cuối gửi model.",
       "keepLastMessages": "Giữ tin nhắn cuối",
       "keepLastMessagesTip": "Số tin nhắn gần nhất giữ lại sau khi nén. Các tin nhắn cũ hơn được thay thế bằng bản tóm tắt.",
       "timeoutSeconds": "Thời gian chờ (giây)",
       "timeoutSecondsTip": "Thời gian tối đa chờ bản tóm tắt nén ngữ cảnh trước khi giữ nguyên lịch sử cũ.",
       "memoryFlush": "Ghi nhớ trước nén",
-      "memoryFlushTip": "Trước khi nén, agent được một lượt để lưu ngữ cảnh quan trọng vào file bộ nhớ. Cũng kích hoạt trích xuất Knowledge Graph."
+      "memoryFlushTip": "Trước khi nén, agent được một lượt để lưu ngữ cảnh quan trọng vào file bộ nhớ. Cũng kích hoạt trích xuất Knowledge Graph.",
+      "maxRequestShare": "Phần request tối đa (0-1)",
+      "maxRequestShareTip": "Tỷ lệ tối đa của cửa sổ ngữ cảnh agent được phép dùng cho request cuối gửi model. Nếu vượt, hệ thống sẽ giảm context trước khi gọi model."
     },
     "inboundDebounce": {
       "title": "Debounce đầu vào",
diff --git a/ui/web/src/i18n/locales/zh/agents.json b/ui/web/src/i18n/locales/zh/agents.json
index 91087fd6..e65e076c 100644
--- a/ui/web/src/i18n/locales/zh/agents.json
+++ b/ui/web/src/i18n/locales/zh/agents.json
@@ -797,15 +797,17 @@
     },
     "compaction": {
       "title": "压缩",
-      "description": "上下文窗口压缩和压缩前记忆设置",
+      "description": "最终请求上下文保护、历史压缩和记忆刷新设置",
       "maxHistoryShare": "最大历史份额 (0-1)",
-      "maxHistoryShareTip": "上下文窗口用于对话历史的最大比例（如0.85 = 85%）。超过时触发压缩。",
+      "maxHistoryShareTip": "仅用于回合后的历史压缩阈值，不是最终请求的总限制。",
       "keepLastMessages": "保留最后消息数",
       "keepLastMessagesTip": "压缩后保留的最近消息数。旧消息被摘要替换。",
       "timeoutSeconds": "超时秒数",
       "timeoutSecondsTip": "等待上下文压缩摘要的最长时间，超时后保留原始历史。",
       "memoryFlush": "压缩前记忆",
-      "memoryFlushTip": "压缩前，Agent可以将重要上下文保存到记忆文件。同时触发知识图谱提取。"
+      "memoryFlushTip": "压缩前，Agent可以将重要上下文保存到记忆文件。同时触发知识图谱提取。",
+      "maxRequestShare": "最大请求份额 (0-1)",
+      "maxRequestShareTip": "最终发送给模型的请求最多可占用智能体上下文窗口的比例。超过时，系统会先缩减上下文再调用模型。"
     },
     "inboundDebounce": {
       "title": "入站防抖",
diff --git a/ui/web/src/pages/agents/agent-detail/config-sections/compaction-section.tsx b/ui/web/src/pages/agents/agent-detail/config-sections/compaction-section.tsx
index 7a1c8f6b..f97a80e4 100644
--- a/ui/web/src/pages/agents/agent-detail/config-sections/compaction-section.tsx
+++ b/ui/web/src/pages/agents/agent-detail/config-sections/compaction-section.tsx
@@ -20,6 +20,16 @@ export function CompactionSection({ value, onChange }: CompactionSectionProps) {
       </div>
       <div className="rounded-lg border p-3 space-y-4 sm:p-4">
       <div className="grid grid-cols-1 gap-4 sm:grid-cols-2">
+        <div className="space-y-2">
+          <InfoLabel tip={t(`${s}.maxRequestShareTip`)}>{t(`${s}.maxRequestShare`)}</InfoLabel>
+          <Input
+            type="number"
+            step="0.05"
+            placeholder="0.85"
+            value={value.maxRequestShare ?? ""}
+            onChange={(e) => onChange({ ...value, maxRequestShare: numOrUndef(e.target.value) })}
+          />
+        </div>
         <div className="space-y-2">
           <InfoLabel tip={t(`${s}.maxHistoryShareTip`)}>{t(`${s}.maxHistoryShare`)}</InfoLabel>
           <Input
diff --git a/ui/web/src/types/agent.ts b/ui/web/src/types/agent.ts
index 8fdd2fc4..568fe51f 100644
--- a/ui/web/src/types/agent.ts
+++ b/ui/web/src/types/agent.ts
@@ -28,6 +28,7 @@ export interface SubagentsConfig {
 export interface CompactionConfig {
   reserveTokensFloor?: number;
   maxHistoryShare?: number;
+  maxRequestShare?: number;
   keepLastMessages?: number;
   timeoutSeconds?: number;
   memoryFlush?: {