agent: emit hook timeout/start-failure warnings as info events

- Add Warning field to HookResult
- runHookCmd sets Warning on timeout and start failure
- Hooks.Run collects warnings across commands
- All hook call sites emit warnings via infoEvent
- Test verifies timeout warning is surfaced

pkg/agent/core.go

@@ -500,6 +500,9 @@ func (s *agentCore) fireAgentSpawn(ctx context.Context, handler EventHandler) {
 	if result.Ran {
 		handler(infoEvent(hooksRan(1)))
 	}
+	if result.Warning != "" {
+		handler(infoEvent(result.Warning))
+	}
 	if result.Context != "" {
 		s.loopcfg.systemPrompt += "\n\n---\n\n" + result.Context
 	}
@@ -689,6 +692,9 @@ func (s *agentCore) executeTurn(ctx context.Context, input string, handler Event
 		handler(infoEvent("hook blocked prompt"))
 		return ""
 	}
+	if hookResult.Warning != "" {
+		handler(infoEvent(hookResult.Warning))
+	}
 	if hookResult.Context != "" {
 		input += "\n" + hookResult.Context
 	}
@@ -744,6 +750,9 @@ func (s *agentCore) executeTurn(ctx context.Context, input string, handler Event
 			if pre.Ran {
 				handler(infoEvent(hooksRan(1)))
 			}
+			if pre.Warning != "" {
+				handler(infoEvent(pre.Warning))
+			}
 			if !pre.Blocked {
 				if pre.Context != "" {
 					s.session.appendUserMessage(pre.Context)
@@ -758,6 +767,9 @@ func (s *agentCore) executeTurn(ctx context.Context, input string, handler Event
 				if post.Ran {
 					handler(infoEvent(hooksRan(1)))
 				}
+				if post.Warning != "" {
+					handler(infoEvent(post.Warning))
+				}
 				if post.Context != "" {
 					s.session.appendUserMessage(post.Context)
 				}
@@ -783,6 +795,9 @@ func (s *agentCore) executeTurn(ctx context.Context, input string, handler Event
 		"session_id": s.sessionID,
 		"cwd":        s.CWD(),
 	}, s.log)
+	if stopResult.Warning != "" {
+		handler(infoEvent(stopResult.Warning))
+	}
 
 	s.saveSession()
 
@@ -1007,6 +1022,9 @@ func (s *agentCore) handleCommand(ctx context.Context, input string, handler Eve
 			if pre.Ran {
 				handler(infoEvent(hooksRan(1)))
 			}
+			if pre.Warning != "" {
+				handler(infoEvent(pre.Warning))
+			}
 			if pre.Blocked {
 				handler(infoEvent("compact cancelled by hook"))
 				return
@@ -1022,6 +1040,9 @@ func (s *agentCore) handleCommand(ctx context.Context, input string, handler Eve
 			if post.Ran {
 				handler(infoEvent(hooksRan(1)))
 			}
+			if post.Warning != "" {
+				handler(infoEvent(post.Warning))
+			}
 			if post.Context != "" {
 				s.session.appendUserMessage(post.Context)
 			}

pkg/agent/core_test.go

@@ -1893,8 +1893,7 @@ func TestHookTimeout_Branch(t *testing.T) {
 	t.Cleanup(func() { hookTimeout = old })
 
 	// A hook that sleeps longer than the timeout. The timeout branch kills the
-	// process and returns HookResult{} (Ran=false), so the turn is NOT blocked
-	// and the backend runs normally.
+	// process and returns a warning, but does not block the turn.
 	hooks := Hooks{HookPreTurn: []string{"sleep 10"}}
 	c := newCore(t, nil, hooks)
 	evs := collectEvents(context.Background(), c, "hello")
@@ -1906,6 +1905,17 @@ func TestHookTimeout_Branch(t *testing.T) {
 	if c.State() != "idle" {
 		t.Errorf("State() = %q after timeout hook; want idle", c.State())
 	}
+	// A timeout warning should have been emitted.
+	infos := byRole(evs, "info")
+	found := false
+	for _, s := range infos {
+		if strings.Contains(s, "timed out") {
+			found = true
+		}
+	}
+	if !found {
+		t.Errorf("expected 'timed out' warning in info events; got %v", infos)
+	}
 }
 
 // --- /backend with injected newBackend ---

pkg/agent/hooks.go

@@ -39,6 +39,9 @@ type HookResult struct {
 	Blocked bool
 	// Context is stdout from the hook, injected into the conversation.
 	Context string
+	// Warning, if non-empty, is a message about hook execution problems
+	// (e.g. timeout, start failure) that should be surfaced to the user.
+	Warning string
 }
 
 // Run executes all commands for the named hook in order, sending payload as
@@ -61,20 +64,24 @@ func (h Hooks) Run(ctx context.Context, name string, payload any, log *olog.Logg
 	}
 
 	var contextParts []string
+	var warnings []string
 	for _, cmdStr := range cmds {
 		log.Debug("hook %s: cmd=%q", name, cmdStr)
 		result := runHookCmd(ctx, name, cmdStr, payloadJSON, cwd, log)
+		if result.Warning != "" {
+			warnings = append(warnings, result.Warning)
+		}
 		if !result.Ran {
 			continue
 		}
 		if result.Blocked {
-			return HookResult{Ran: true, Blocked: true, Context: result.Context}
+			return HookResult{Ran: true, Blocked: true, Context: result.Context, Warning: strings.Join(warnings, "; ")}
 		}
 		if result.Context != "" {
 			contextParts = append(contextParts, result.Context)
 		}
 	}
-	return HookResult{Ran: true, Context: strings.Join(contextParts, "\n")}
+	return HookResult{Ran: true, Context: strings.Join(contextParts, "\n"), Warning: strings.Join(warnings, "; ")}
 }
 
 func runHookCmd(ctx context.Context, name, cmdStr string, payloadJSON []byte, cwd string, log *olog.Logger) HookResult {
@@ -91,7 +98,7 @@ func runHookCmd(ctx context.Context, name, cmdStr string, payloadJSON []byte, cw
 	done := make(chan error, 1)
 	if err := cmd.Start(); err != nil {
 		log.Debug("hook %s: start error: %v", name, err)
-		return HookResult{}
+		return HookResult{Ran: true, Warning: fmt.Sprintf("hook %s: failed to start: %v", name, err)}
 	}
 	go func() { done <- cmd.Wait() }()
 
@@ -130,7 +137,7 @@ func runHookCmd(ctx context.Context, name, cmdStr string, payloadJSON []byte, cw
 		cmd.Process.Kill() //nolint:errcheck
 		<-done
 		log.Debug("hook %s: timed out after %ds", name, hookTimeout)
-		return HookResult{}
+		return HookResult{Ran: true, Warning: fmt.Sprintf("hook %s: timed out after %ds", name, hookTimeout)}
 	}
 }