coder · hugodutka · Jun 12, 2026 · Jun 18, 2026 · Jun 18, 2026
diff --git a/coderd/x/chatd/auto_archive_internal_test.go b/coderd/x/chatd/auto_archive_internal_test.go
@@ -293,9 +293,7 @@ func (f *workerTestFixture) newArchiveWorkerWithOptions(t *testing.T, opts chatW
 	if opts.NotificationsEnqueuer == nil {
 		opts.NotificationsEnqueuer = notificationstest.NewFakeEnqueuer()
 	}
-	worker, err := newChatWorker(nil, opts)
-	require.NoError(t, err)
-	return worker
+	return newChatWorker(nil, opts.WorkerID, opts.Store, opts.Pubsub, opts.MessagePartBuffer, opts)
 }
 
 func mockAuditorPtr(auditor *audit.MockAuditor) *atomic.Pointer[audit.Auditor] {

diff --git a/coderd/x/chatd/chatd.go b/coderd/x/chatd/chatd.go
@@ -2275,31 +2275,27 @@ type manualTitleGenerationError struct {
 // read; the title_change pubsub event it publishes remains the source of
 // truth for clients.
 type generatedChatTitle struct {
-	mu    sync.RWMutex
-	title string
+	title atomic.Value // string
 }
 
 func (t *generatedChatTitle) Store(title string) {
 	if t == nil || title == "" {
 		return
 	}
 
-	t.mu.Lock()
-	t.title = title
-	t.mu.Unlock()
+	t.title.Store(title)
 }
 
 func (t *generatedChatTitle) Load() (string, bool) {
 	if t == nil {
 		return "", false
 	}
 
-	t.mu.RLock()
-	defer t.mu.RUnlock()
-	if t.title == "" {
+	title, ok := t.title.Load().(string)
+	if !ok || title == "" {
 		return "", false
 	}
-	return t.title, true
+	return title, true
 }
 
 func (e *manualTitleGenerationError) Error() string {
@@ -3421,32 +3417,32 @@ func New(ps pubsub.Pubsub, cfg Config) *Server {
 		p.metrics = chatloop.NopMetrics()
 	}
 	p.messagePartBuffer = messagepartbuffer.New(messagepartbuffer.Options{Clock: clk})
-	localStreamPartsDialer := NewLocalStreamPartsDialer(LocalStreamPartsDialerConfig{
-		Buffer: p.messagePartBuffer,
-		Logger: cfg.Logger,
-	})
-	p.streamPartsDialer = streamPartsDialerForServer(workerID, localStreamPartsDialer, cfg.StreamPartsDialer)
-	p.streamSyncPoller = newStreamSyncPoller(ctx, cfg.Database, clk, cfg.Logger.Named("chatstream"))
-	p.streamSyncPoller.Start()
-	chatWorker, err := newChatWorker(p, chatWorkerOptions{
-		WorkerID:              workerID,
-		Store:                 cfg.Database,
-		Pubsub:                ps,
+	workerOpts := chatWorkerOptions{
 		Logger:                cfg.Logger.Named("chatworker"),
 		Clock:                 clk,
-		MessagePartBuffer:     p.messagePartBuffer,
 		AcquisitionInterval:   pendingChatAcquireInterval,
 		AcquisitionBatchSize:  maxChatsPerAcquire,
 		HeartbeatInterval:     chatHeartbeatInterval,
 		HeartbeatStaleSeconds: int32(inFlightChatStaleAfter.Seconds()),
 		NotificationsEnqueuer: notificationsEnqueuer,
 		Auditor:               cfg.Auditor,
 		AutoArchiveRecords:    chatAutoArchiveRecords,
-	})
-	if err != nil {
-		panic("chatd: create chat worker: " + err.Error())
 	}
-	p.chatWorker = chatWorker
+	localStreamPartsDialer := NewLocalStreamPartsDialer(LocalStreamPartsDialerConfig{
+		Buffer: p.messagePartBuffer,
+		Logger: cfg.Logger,
+	})
+	p.streamPartsDialer = streamPartsDialerForServer(workerID, localStreamPartsDialer, cfg.StreamPartsDialer)
+	p.streamSyncPoller = newStreamSyncPoller(ctx, cfg.Database, clk, cfg.Logger.Named("chatstream"))
+	p.streamSyncPoller.Start()
+	p.chatWorker = newChatWorker(
+		p,
+		workerID,
+		cfg.Database,
+		ps,
+		p.messagePartBuffer,
+		workerOpts,
+	)
 
 	//nolint:gocritic // The chat processor uses a scoped chatd context.
 	ctx = dbauthz.AsChatd(ctx)
@@ -4134,7 +4130,7 @@ func (p *Server) loadPersonalSkillBody(
 	return parsed, nil
 }
 
-func (p *Server) appendRootChatTools(
+func (p *Server) appendRootChatToolsWithoutWorkspaceContextPersistence(
 	ctx context.Context,
 	tools []fantasy.AgentTool,
 	opts rootChatToolsOptions,
@@ -4145,14 +4141,11 @@ func (p *Server) appendRootChatTools(
 		// build logs before the tool completes.
 		p.publishChatPubsubEvent(updatedChat, codersdk.ChatWatchEventKindStatusChange, nil)
 
-		// Note: we intentionally do not insert AGENTS.md / workspace
-		// context here. Local tool callbacks must not mutate chat
-		// history while a local-tool generation task is in flight,
-		// because that advances history_version before the tool
-		// result is committed and exits the local-tool commit as
-		// stale. Workspace context is persisted by the
-		// persist_workspace_context generation action in a later
-		// pass.
+		// Do not persist workspace context from this callback. Local
+		// tool callbacks run while a generation task is fenced by
+		// history_version; mutating chat history here would make that
+		// commit stale. The generation state machine runs
+		// persist_workspace_context after this tool result commits.
 
 		// Prime the workspace MCP tools cache while the create_workspace
 		// or start_workspace tool is still running. The AgentID guard

diff --git a/coderd/x/chatd/generation_preparer.go b/coderd/x/chatd/generation_preparer.go
@@ -352,7 +352,7 @@ func (server *Server) prepareGeneration(
 		tools = append(tools, chattool.NewAskUserQuestionTool())
 	}
 	if isRootChat {
-		tools = server.appendRootChatTools(ctx, tools, rootChatToolsOptions{
+		tools = server.appendRootChatToolsWithoutWorkspaceContextPersistence(ctx, tools, rootChatToolsOptions{
 			chat:            chat,
 			modelConfigID:   modelConfig.ID,
 			workspaceCtx:    &workspaceCtx,

diff --git a/coderd/x/chatd/helpers_test.go b/coderd/x/chatd/helpers_test.go
@@ -269,10 +269,31 @@ func testOptions(t *testing.T, f *workerTestFixture, starter chatWorkerTaskStart
 	}
 }
 
-func startWorker(t *testing.T, opts chatWorkerOptions) *chatWorker {
+func testWorkerDeps(f *workerTestFixture, opts chatWorkerOptions) chatWorkerDependencies {
+	workerID := opts.WorkerID
+	if workerID == uuid.Nil {
+		workerID = uuid.New()
+	}
+	store := opts.Store
+	if store == nil {
+		store = f.db
+	}
+	pubsub := opts.Pubsub
+	if pubsub == nil {
+		pubsub = f.pubsub
+	}
+	return chatWorkerDependencies{
+		WorkerID:          workerID,
+		Store:             store,
+		Pubsub:            pubsub,
+		MessagePartBuffer: opts.MessagePartBuffer,
+	}
+}
+
+func startWorker(t *testing.T, f *workerTestFixture, opts chatWorkerOptions) *chatWorker {
 	t.Helper()
-	worker, err := newChatWorker(nil, opts)
-	require.NoError(t, err)
+	deps := testWorkerDeps(f, opts)
+	worker := newChatWorker(nil, deps.WorkerID, deps.Store, deps.Pubsub, deps.MessagePartBuffer, opts)
 	require.NoError(t, worker.Start(context.Background()))
 	t.Cleanup(func() { require.NoError(t, worker.Close()) })
 	return worker

diff --git a/coderd/x/chatd/options.go b/coderd/x/chatd/options.go
@@ -8,7 +8,6 @@ import (
 
 	"github.com/google/uuid"
 	"github.com/prometheus/client_golang/prometheus"
-	"golang.org/x/xerrors"
 
 	"cdr.dev/slog/v3"
 	"github.com/coder/coder/v2/coderd/audit"
@@ -94,19 +93,18 @@ type chatWorkerOptions struct {
 	TaskRetryMaxBackoff        time.Duration
 }
 
-func (o chatWorkerOptions) withDefaults() (chatWorkerOptions, error) {
-	if o.Store == nil {
-		return chatWorkerOptions{}, xerrors.New("chatworker: store is required")
-	}
-	if o.Pubsub == nil {
-		return chatWorkerOptions{}, xerrors.New("chatworker: pubsub is required")
-	}
-	if o.TaskStarter == nil && o.MessagePartBuffer == nil {
-		return chatWorkerOptions{}, xerrors.New("chatworker: task starter or message part buffer is required")
-	}
-	if o.WorkerID == uuid.Nil {
-		return chatWorkerOptions{}, xerrors.New("chatworker: worker ID is required")
-	}
+type chatWorkerDependencies struct {
+	WorkerID          uuid.UUID
+	Store             database.Store
+	Pubsub            chatWorkerPubsub
+	MessagePartBuffer *messagepartbuffer.Buffer
+}
+
+func (o chatWorkerOptions) withDefaults(deps chatWorkerDependencies) chatWorkerOptions {
+	o.WorkerID = deps.WorkerID
+	o.Store = deps.Store
+	o.Pubsub = deps.Pubsub
+	o.MessagePartBuffer = deps.MessagePartBuffer
 	if o.Clock == nil {
 		o.Clock = quartz.NewReal()
 	}
@@ -155,5 +153,5 @@ func (o chatWorkerOptions) withDefaults() (chatWorkerOptions, error) {
 	if o.TaskRetryMaxBackoff < o.TaskRetryInitialBackoff {
 		o.TaskRetryMaxBackoff = o.TaskRetryInitialBackoff
 	}
-	return o, nil
+	return o
 }
diff --git a/coderd/x/chatd/runner_test.go b/coderd/x/chatd/runner_test.go
@@ -18,7 +18,7 @@ func TestRunner_IgnoresDuplicateStateNotifications(t *testing.T) {
 	f := newWorkerTestFixture(t)
 	chat := f.createRunningChat(t)
 	starter := newBlockingTaskStarter(false)
-	startWorker(t, testOptions(t, f, starter))
+	startWorker(t, f, testOptions(t, f, starter))
 	starter.waitCall(t, taskKindGeneration, chat.ID)
 	latest, err := f.db.GetChatByID(testutil.Context(t, testutil.WaitShort), chat.ID)
 	require.NoError(t, err)
@@ -33,7 +33,7 @@ func TestRunner_CancelsActiveTaskWhenHistoryChanges(t *testing.T) {
 	f := newWorkerTestFixture(t)
 	chat := f.createRunningChat(t)
 	starter := newBlockingTaskStarter(false)
-	startWorker(t, testOptions(t, f, starter))
+	startWorker(t, f, testOptions(t, f, starter))
 	first := starter.waitCall(t, taskKindGeneration, chat.ID)
 
 	updated := commitAssistantStep(t, f, chat.ID, "first step")
@@ -49,7 +49,7 @@ func TestRunner_CancelsActiveTaskWhenStatusChanges(t *testing.T) {
 	f := newWorkerTestFixture(t)
 	chat := f.createRunningChat(t)
 	starter := newBlockingTaskStarter(false)
-	startWorker(t, testOptions(t, f, starter))
+	startWorker(t, f, testOptions(t, f, starter))
 	first := starter.waitCall(t, taskKindGeneration, chat.ID)
 
 	updated := interruptChat(t, f, chat.ID)
@@ -64,7 +64,7 @@ func TestRunner_CleansUpOnOwnershipTakeover(t *testing.T) {
 	f := newWorkerTestFixture(t)
 	chat := f.createRunningChat(t)
 	starter := newBlockingTaskStarter(false)
-	startWorker(t, testOptions(t, f, starter))
+	startWorker(t, f, testOptions(t, f, starter))
 	first := starter.waitCall(t, taskKindGeneration, chat.ID)
 
 	acquireChat(t, f, chat.ID, uuid.New(), uuid.New())
@@ -78,7 +78,7 @@ func TestRunner_SerializesReplacementTasksForSameHistoryAndStatus(t *testing.T)
 	chat := f.createRunningChat(t)
 	starter := newBlockingTaskStarter(true)
 	defer starter.releaseAll()
-	startWorker(t, testOptions(t, f, starter))
+	startWorker(t, f, testOptions(t, f, starter))
 	first := starter.waitCall(t, taskKindGeneration, chat.ID)
 
 	forceExecutionStateAndPublish(t, f, chat.ID, database.ChatStatusInterrupting, false)
@@ -97,7 +97,7 @@ func TestRunner_AllowsReplacementForDifferentHistoryOrStatus(t *testing.T) {
 	chat := f.createRunningChat(t)
 	starter := newBlockingTaskStarter(true)
 	defer starter.releaseAll()
-	startWorker(t, testOptions(t, f, starter))
+	startWorker(t, f, testOptions(t, f, starter))
 	first := starter.waitCall(t, taskKindGeneration, chat.ID)
 
 	updated := commitAssistantStep(t, f, chat.ID, "different history")
@@ -117,7 +117,7 @@ func TestRunner_TaskTimeoutRetries(t *testing.T) {
 	opts.Clock = clock
 	opts.TaskRetryInitialBackoff = time.Minute
 	opts.TaskRetryMaxBackoff = time.Minute
-	startWorker(t, opts)
+	startWorker(t, f, opts)
 
 	timeoutTrap.MustWait(testutil.Context(t, testutil.WaitLong)).MustRelease(testutil.Context(t, testutil.WaitLong))
 	timeoutTrap.Close()
@@ -143,7 +143,7 @@ func TestWorker_RoutesDatabaseSyncStateToActiveRunner(t *testing.T) {
 	opts := testOptions(t, f, starter)
 	opts.Clock = clock
 	opts.RunnerSyncInterval = time.Minute
-	startWorker(t, opts)
+	startWorker(t, f, opts)
 	first := starter.waitCall(t, taskKindGeneration, chat.ID)
 
 	forceExecutionState(t, f, chat.ID, database.ChatStatusInterrupting, false)
@@ -157,7 +157,7 @@ func TestWorker_CleanupStopsRoutingAndCancelsTasks(t *testing.T) {
 	f := newWorkerTestFixture(t)
 	chat := f.createRunningChat(t)
 	starter := newBlockingTaskStarter(false)
-	startWorker(t, testOptions(t, f, starter))
+	startWorker(t, f, testOptions(t, f, starter))
 	first := starter.waitCall(t, taskKindGeneration, chat.ID)
 
 	latest := acquireChat(t, f, chat.ID, uuid.New(), uuid.New())

diff --git a/coderd/x/chatd/tasks_test.go b/coderd/x/chatd/tasks_test.go
@@ -1124,25 +1124,27 @@ func startRealTaskWorker(t *testing.T, f *taskTestFixture) *chatWorker {
 	t.Helper()
 	buffer := messagepartbuffer.New(messagepartbuffer.Options{})
 	t.Cleanup(buffer.Close)
-	worker, err := newChatWorker(nil, chatWorkerOptions{
-		WorkerID:                   uuid.New(),
-		Store:                      f.db,
-		Pubsub:                     f.pubsub,
-		Logger:                     slog.Make(),
-		MessagePartBuffer:          buffer,
-		AcquisitionInterval:        time.Hour,
-		AcquisitionBatchSize:       10,
-		RunnerSyncInterval:         time.Hour,
-		HeartbeatInterval:          time.Hour,
-		HeartbeatCleanupInterval:   time.Hour,
-		HeartbeatStaleSeconds:      30,
-		StateChannelSize:           16,
-		RunnerManagerChannelSize:   16,
-		AcquisitionWakeChannelSize: 1,
-		TaskRetryInitialBackoff:    time.Millisecond,
-		TaskRetryMaxBackoff:        time.Millisecond,
-	})
-	require.NoError(t, err)
+	worker := newChatWorker(
+		nil,
+		uuid.New(),
+		f.db,
+		f.pubsub,
+		buffer,
+		chatWorkerOptions{
+			Logger:                     slog.Make(),
+			AcquisitionInterval:        time.Hour,
+			AcquisitionBatchSize:       10,
+			RunnerSyncInterval:         time.Hour,
+			HeartbeatInterval:          time.Hour,
+			HeartbeatCleanupInterval:   time.Hour,
+			HeartbeatStaleSeconds:      30,
+			StateChannelSize:           16,
+			RunnerManagerChannelSize:   16,
+			AcquisitionWakeChannelSize: 1,
+			TaskRetryInitialBackoff:    time.Millisecond,
+			TaskRetryMaxBackoff:        time.Millisecond,
+		},
+	)
 	require.NoError(t, worker.Start(context.Background()))
 	t.Cleanup(func() { require.NoError(t, worker.Close()) })
 	return worker

diff --git a/coderd/x/chatd/worker.go b/coderd/x/chatd/worker.go
@@ -13,6 +13,7 @@ import (
 	"github.com/coder/coder/v2/coderd/database"
 	coderdpubsub "github.com/coder/coder/v2/coderd/pubsub"
 	"github.com/coder/coder/v2/coderd/x/chatd/chatstate"
+	"github.com/coder/coder/v2/coderd/x/chatd/messagepartbuffer"
 )
 
 // chatWorker owns chat acquisition and runner lifecycle for one process.
@@ -32,12 +33,23 @@ type chatWorker struct {
 
 // newChatWorker constructs a chat worker. The worker is idle until Start is
 // called.
-func newChatWorker(server *Server, opts chatWorkerOptions) (*chatWorker, error) {
-	withDefaults, err := opts.withDefaults()
-	if err != nil {
-		return nil, err
+func newChatWorker(
+	server *Server,
+	workerID uuid.UUID,
+	store database.Store,
+	pubsub chatWorkerPubsub,
+	messagePartBuffer *messagepartbuffer.Buffer,
+	opts chatWorkerOptions,
+) *chatWorker {
+	return &chatWorker{
+		server: server,
+		opts: opts.withDefaults(chatWorkerDependencies{
+			WorkerID:          workerID,
+			Store:             store,
+			Pubsub:            pubsub,
+			MessagePartBuffer: messagePartBuffer,
+		}),
 	}
-	return &chatWorker{server: server, opts: withDefaults}, nil
 }
 
 // chatWorkerID returns this worker's configured worker ID.