fix(spawn): resolve parent agent from context in managed mode (#4)

In managed mode, multiple agents share a single tool registry. The spawn
and subagent tools were constructed with a hardcoded parentID of "default",
which does not exist as an agent in managed mode deployments. This caused
subagent announces to fail with "agent default not found" when any
non-default agent (e.g. a secondary agent) tried to spawn a subagent.

Fix: add ctxAgentKey to tool context keys (same pattern as channel/chatID),
inject the calling agent's key from the loop, and read it in spawn/subagent
tools with a fallback to the construction-time default for backward
compatibility with standalone mode.

internal/agent/loop.go

@@ -434,6 +434,9 @@ func (l *Loop) runLoop(ctx context.Context, req RunRequest) (*RunResult, error)
 		}
 	}
 
+	// Inject agent key into context for tool-level resolution (managed mode: multiple agents share tool registry)
+	ctx = tools.WithToolAgentKey(ctx, l.id)
+
 	// Security: truncate oversized user messages gracefully (feed truncation notice into LLM)
 	maxChars := l.maxMessageChars
 	if maxChars <= 0 {

internal/tools/context_keys.go

@@ -20,6 +20,7 @@ const (
 	ctxSandboxKey toolContextKey = "tool_sandbox_key"
 	ctxAsyncCB    toolContextKey = "tool_async_cb"
 	ctxWorkspace  toolContextKey = "tool_workspace"
+	ctxAgentKey   toolContextKey = "tool_agent_key"
 )
 
 func WithToolChannel(ctx context.Context, channel string) context.Context {
@@ -76,6 +77,18 @@ func ToolWorkspaceFromCtx(ctx context.Context) string {
 	return v
 }
 
+// WithToolAgentKey injects the calling agent's key into context.
+// In managed mode multiple agents share a single tool registry; the agent key
+// lets tools like spawn/subagent identify which agent is the parent.
+func WithToolAgentKey(ctx context.Context, key string) context.Context {
+	return context.WithValue(ctx, ctxAgentKey, key)
+}
+
+func ToolAgentKeyFromCtx(ctx context.Context) string {
+	v, _ := ctx.Value(ctxAgentKey).(string)
+	return v
+}
+
 // --- Vision / ImageGen config (per-agent overrides) ---
 
 const (

internal/tools/subagent_spawn_tool.go

@@ -61,7 +61,13 @@ func (t *SpawnTool) Execute(ctx context.Context, args map[string]interface{}) *R
 	peerKind := ToolPeerKindFromCtx(ctx)
 	callback := ToolAsyncCBFromCtx(ctx)
 
-	msg, err := t.manager.Spawn(ctx, t.parentID, t.depth, task, label, modelOverride,
+	// Resolve parent agent from ctx (managed mode) with fallback to construction-time default
+	parentID := ToolAgentKeyFromCtx(ctx)
+	if parentID == "" {
+		parentID = t.parentID
+	}
+
+	msg, err := t.manager.Spawn(ctx, parentID, t.depth, task, label, modelOverride,
 		channel, chatID, peerKind, callback)
 	if err != nil {
 		return ErrorResult(err.Error())

internal/tools/subagent_tool.go

@@ -148,7 +148,13 @@ func (t *SubagentTool) executeRun(ctx context.Context, args map[string]interface
 	channel := ToolChannelFromCtx(ctx)
 	chatID := ToolChatIDFromCtx(ctx)
 
-	result, iterations, err := t.manager.RunSync(ctx, t.parentID, t.depth, task, label,
+	// Resolve parent agent from ctx (managed mode) with fallback to construction-time default
+	parentID := ToolAgentKeyFromCtx(ctx)
+	if parentID == "" {
+		parentID = t.parentID
+	}
+
+	result, iterations, err := t.manager.RunSync(ctx, parentID, t.depth, task, label,
 		channel, chatID)
 	if err != nil {
 		return ErrorResult(fmt.Sprintf("Subagent '%s' failed: %v", label, err))