fix(mcp): wire per-user MCP tool discovery into agent pipeline

MCP servers with require_user_credentials (e.g. Notion) were defined
but never loaded into the agent's tool registry. Three gaps:

1. getUserMCPTools was defined but never called — add call in
   makeBuildFilteredTools before FilterTools runs each iteration.

2. hasMCPTools stayed false when only user-credential servers existed,
   so agentToolPolicyWithMCP never injected "group:mcp" into alsoAllow.
   Now set true when mcpUserCredSrvs is non-empty.

3. Per-user BridgeTools were registered in the registry but never added
   to the "mcp" tool group, so expandSpec("group:mcp") returned empty.
   Add MergeToolGroup helper for additive group updates.

Also add debug log when getUserMCPTools skips due to empty userID.

internal/agent/loop_mcp_user.go

@@ -15,6 +15,9 @@ import (
 // connections are established via pool.AcquireUser() and BridgeTools created.
 func (l *Loop) getUserMCPTools(ctx context.Context, userID string) []tools.Tool {
 	if len(l.mcpUserCredSrvs) == 0 || l.mcpPool == nil || l.mcpStore == nil || userID == "" {
+		if userID == "" && len(l.mcpUserCredSrvs) > 0 {
+			slog.Debug("mcp.user_tools_skipped", "reason", "empty_user_id", "servers", len(l.mcpUserCredSrvs))
+		}
 		return nil
 	}
 
@@ -100,6 +103,13 @@ func (l *Loop) getUserMCPTools(ctx context.Context, userID string) []tools.Tool
 
 	if len(userTools) > 0 {
 		l.mcpUserTools.Store(userID, userTools)
+		// Update "mcp" tool group so policy expansion via alsoAllow includes
+		// per-user tools. MergeToolGroup is additive — safe for concurrent users.
+		var names []string
+		for _, t := range userTools {
+			names = append(names, t.Name())
+		}
+		tools.MergeToolGroup("mcp", names)
 		slog.Info("mcp.user_tools_loaded", "user", userID, "tools", len(userTools))
 	}
 	return userTools

internal/agent/loop_pipeline_callbacks.go

@@ -191,6 +191,11 @@ func (l *Loop) makeInjectReminders(req *RunRequest) func(ctx context.Context, in
 
 func (l *Loop) makeBuildFilteredTools(req *RunRequest) func(state *pipeline.RunState) ([]providers.ToolDefinition, error) {
 	return func(state *pipeline.RunState) ([]providers.ToolDefinition, error) {
+		// Load per-user MCP tools (Notion, etc.) into registry before filtering.
+		// Servers with require_user_credentials are deferred at startup and
+		// connected per-request here with the actual user's credentials.
+		l.getUserMCPTools(state.Ctx, state.Input.UserID)
+
 		maxIter := l.maxIterations
 		if req.MaxIterations > 0 && req.MaxIterations < maxIter {
 			maxIter = req.MaxIterations

internal/agent/resolver.go

@@ -305,6 +305,12 @@ func NewManagedResolver(deps ResolverDeps) ResolverFunc {
 				slog.Warn("failed to load MCP servers for agent", "agent", agentKey, "error", err)
 			} else {
 				mcpUserCredSrvs = mcpMgr.UserCredServers()
+				// User-credential servers (Notion, etc.) are deferred at startup
+				// but will produce tools per-request via getUserMCPTools.
+				// Set flag so agentToolPolicyWithMCP injects "group:mcp" into alsoAllow.
+				if len(mcpUserCredSrvs) > 0 {
+					hasMCPTools = true
+				}
 				if mcpMgr.IsSearchMode() {
 					// Search mode: too many tools — register mcp_tool_search meta-tool.
 					// Also wire lazy activator so deferred tools can be called by name directly.

internal/tools/policy.go

@@ -50,6 +50,25 @@ func RegisterToolGroup(name string, members []string) {
 	toolGroupsMu.Unlock()
 }
 
+// MergeToolGroup adds members to an existing tool group without removing existing entries.
+// Used by per-user MCP tool loading to extend the "mcp" group incrementally.
+func MergeToolGroup(name string, members []string) {
+	toolGroupsMu.Lock()
+	defer toolGroupsMu.Unlock()
+	existing := toolGroups[name]
+	seen := make(map[string]bool, len(existing))
+	for _, m := range existing {
+		seen[m] = true
+	}
+	for _, m := range members {
+		if !seen[m] {
+			existing = append(existing, m)
+			seen[m] = true
+		}
+	}
+	toolGroups[name] = existing
+}
+
 // UnregisterToolGroup removes a dynamic tool group.
 func UnregisterToolGroup(name string) {
 	toolGroupsMu.Lock()