fix: update sidebar diff status on WebSocket events (#23116)

## Problem

The sidebar diff status (PR icon, +additions/-deletions, file count) was
not updating in real-time. Users had to reload the page to see changes.

Two root causes:

1. **Frontend**: The `diff_status_change` WebSocket handler in
`AgentsPage.tsx` had an early `return` (line 398) that skipped
`updateInfiniteChatsCache`, so the sidebar's cache was never updated.
Even for other event types, the cache merge only spread `status` and
`title` — never `diff_status`.

2. **Server**: `publishChatPubsubEvent` in `chatd.go` constructed a
minimal `Chat` payload without `DiffStatus`, so even if the frontend
consumed the event, `updatedChat.diff_status` would be `undefined`.

## Fix

### Server (`coderd/chatd/chatd.go`)
- `publishChatPubsubEvent` now accepts an optional
`*codersdk.ChatDiffStatus` parameter; when non-nil it's set on the
outgoing `Chat` payload.
- `PublishDiffStatusChange` fetches the diff status from the DB,
converts it, and passes it through.
- Added `convertDBChatDiffStatus` (mirrors `coderd/chats.go`'s converter
to avoid circular import).
- All other callers pass `nil`.

### Frontend (`site/src/pages/AgentsPage/AgentsPage.tsx`)
- Removed the early `return` so `diff_status_change` events fall through
to the cache update logic.
- Added `isDiffStatusEvent` flag and spread `diff_status` into both the
infinite chats cache (sidebar) and the individual chat cache.

coderd/chatd/chatd.go

@@ -347,7 +347,7 @@ func (p *Server) CreateChat(ctx context.Context, opts CreateOptions) (database.C
 		return database.Chat{}, txErr
 	}
 
-	p.publishChatPubsubEvent(chat, coderdpubsub.ChatEventKindCreated)
+	p.publishChatPubsubEvent(chat, coderdpubsub.ChatEventKindCreated, nil)
 	return chat, nil
 }
 
@@ -488,7 +488,7 @@ func (p *Server) SendMessage(
 
 	p.publishMessage(opts.ChatID, result.Message)
 	p.publishStatus(opts.ChatID, result.Chat.Status, result.Chat.WorkerID)
-	p.publishChatPubsubEvent(result.Chat, coderdpubsub.ChatEventKindStatusChange)
+	p.publishChatPubsubEvent(result.Chat, coderdpubsub.ChatEventKindStatusChange, nil)
 	return result, nil
 }
 
@@ -585,7 +585,7 @@ func (p *Server) EditMessage(
 		QueueUpdate: true,
 	})
 	p.publishStatus(opts.ChatID, result.Chat.Status, result.Chat.WorkerID)
-	p.publishChatPubsubEvent(result.Chat, coderdpubsub.ChatEventKindStatusChange)
+	p.publishChatPubsubEvent(result.Chat, coderdpubsub.ChatEventKindStatusChange, nil)
 
 	return result, nil
 }
@@ -605,7 +605,7 @@ func (p *Server) ArchiveChat(ctx context.Context, chatID uuid.UUID) error {
 		return xerrors.Errorf("archive chat: %w", err)
 	}
 
-	p.publishChatPubsubEvent(chat, coderdpubsub.ChatEventKindDeleted)
+	p.publishChatPubsubEvent(chat, coderdpubsub.ChatEventKindDeleted, nil)
 	return nil
 }
 
@@ -625,7 +625,7 @@ func (p *Server) UnarchiveChat(ctx context.Context, chatID uuid.UUID) error {
 		return xerrors.Errorf("unarchive chat: %w", err)
 	}
 
-	p.publishChatPubsubEvent(chat, coderdpubsub.ChatEventKindCreated)
+	p.publishChatPubsubEvent(chat, coderdpubsub.ChatEventKindCreated, nil)
 	return nil
 }
 
@@ -780,7 +780,7 @@ func (p *Server) PromoteQueued(
 	})
 	p.publishMessage(opts.ChatID, promoted)
 	p.publishStatus(opts.ChatID, updatedChat.Status, updatedChat.WorkerID)
-	p.publishChatPubsubEvent(updatedChat, coderdpubsub.ChatEventKindStatusChange)
+	p.publishChatPubsubEvent(updatedChat, coderdpubsub.ChatEventKindStatusChange, nil)
 
 	return result, nil
 }
@@ -877,7 +877,7 @@ func (p *Server) setChatWaiting(ctx context.Context, chatID uuid.UUID) (database
 		return database.Chat{}, err
 	}
 	p.publishStatus(chatID, updatedChat.Status, updatedChat.WorkerID)
-	p.publishChatPubsubEvent(updatedChat, coderdpubsub.ChatEventKindStatusChange)
+	p.publishChatPubsubEvent(updatedChat, coderdpubsub.ChatEventKindStatusChange, nil)
 	return updatedChat, nil
 }
 
@@ -1611,7 +1611,7 @@ func (p *Server) publishChatStreamNotify(chatID uuid.UUID, notify coderdpubsub.C
 
 // publishChatPubsubEvent broadcasts a chat lifecycle event via PostgreSQL
 // pubsub so that all replicas can push updates to watching clients.
-func (p *Server) publishChatPubsubEvent(chat database.Chat, kind coderdpubsub.ChatEventKind) {
+func (p *Server) publishChatPubsubEvent(chat database.Chat, kind coderdpubsub.ChatEventKind, diffStatus *codersdk.ChatDiffStatus) {
 	if p.pubsub == nil {
 		return
 	}
@@ -1637,6 +1637,9 @@ func (p *Server) publishChatPubsubEvent(chat database.Chat, kind coderdpubsub.Ch
 	if chat.WorkspaceID.Valid {
 		sdkChat.WorkspaceID = &chat.WorkspaceID.UUID
 	}
+	if diffStatus != nil {
+		sdkChat.DiffStatus = diffStatus
+	}
 	event := coderdpubsub.ChatEvent{
 		Kind: kind,
 		Chat: sdkChat,
@@ -1672,7 +1675,13 @@ func (p *Server) PublishDiffStatusChange(ctx context.Context, chatID uuid.UUID)
 		return xerrors.Errorf("get chat: %w", err)
 	}
 
-	p.publishChatPubsubEvent(chat, coderdpubsub.ChatEventKindDiffStatusChange)
+	dbStatus, err := p.db.GetChatDiffStatusByChatID(ctx, chatID)
+	if err != nil {
+		return xerrors.Errorf("get chat diff status: %w", err)
+	}
+
+	sdkStatus := db2sdk.ChatDiffStatus(chatID, &dbStatus)
+	p.publishChatPubsubEvent(chat, coderdpubsub.ChatEventKindDiffStatusChange, &sdkStatus)
 	return nil
 }
 
@@ -2041,7 +2050,7 @@ func (p *Server) processChat(ctx context.Context, chat database.Chat) {
 				slog.F("chat_id", chat.ID), slog.Error(readErr))
 		}
 		chat.Status = status
-		p.publishChatPubsubEvent(chat, coderdpubsub.ChatEventKindStatusChange)
+		p.publishChatPubsubEvent(chat, coderdpubsub.ChatEventKindStatusChange, nil)
 
 		if !wasInterrupted {
 			p.maybeSendPushNotification(cleanupCtx, chat, status, lastError, logger)

coderd/chatd/quickgen.go

@@ -111,7 +111,7 @@ func (p *Server) maybeGenerateChatTitle(
 			return
 		}
 		chat.Title = title
-		p.publishChatPubsubEvent(chat, coderdpubsub.ChatEventKindTitleChange)
+		p.publishChatPubsubEvent(chat, coderdpubsub.ChatEventKindTitleChange, nil)
 		return
 	}
 

coderd/chats.go

@@ -2457,7 +2457,7 @@ func convertChat(c database.Chat, diffStatus *database.ChatDiffStatus) codersdk.
 		chat.WorkspaceID = &c.WorkspaceID.UUID
 	}
 	if diffStatus != nil {
-		convertedDiffStatus := convertChatDiffStatus(c.ID, diffStatus)
+		convertedDiffStatus := db2sdk.ChatDiffStatus(c.ID, diffStatus)
 		chat.DiffStatus = &convertedDiffStatus
 	}
 	return chat
@@ -2474,7 +2474,7 @@ func convertChats(chats []database.Chat, diffStatusesByChatID map[uuid.UUID]data
 
 		result[i] = convertChat(c, nil)
 		if diffStatusesByChatID != nil {
-			emptyDiffStatus := convertChatDiffStatus(c.ID, nil)
+			emptyDiffStatus := db2sdk.ChatDiffStatus(c.ID, nil)
 			result[i].DiffStatus = &emptyDiffStatus
 		}
 	}
@@ -2558,86 +2558,6 @@ func convertChatMessages(messages []database.ChatMessage) []codersdk.ChatMessage
 	return result
 }
 
-func convertChatDiffStatus(chatID uuid.UUID, status *database.ChatDiffStatus) codersdk.ChatDiffStatus {
-	result := codersdk.ChatDiffStatus{
-		ChatID: chatID,
-	}
-	if status == nil {
-		return result
-	}
-
-	result.ChatID = status.ChatID
-	if status.Url.Valid {
-		u := strings.TrimSpace(status.Url.String)
-		if u != "" {
-			result.URL = &u
-		}
-	}
-	if result.URL == nil {
-		// Try to build a branch URL from the stored origin.
-		// Since convertChatDiffStatus does not have access to
-		// the API instance, we construct a GitHub provider
-		// directly as a best-effort fallback.
-		// TODO: This uses the default github.com API base URL,
-		// so branch URLs for GitHub Enterprise instances will
-		// be incorrect. To fix this, convertChatDiffStatus
-		// would need access to the external auth configs.
-		gp := gitprovider.New("github", "", nil)
-		if gp != nil {
-			if owner, repo, _, ok := gp.ParseRepositoryOrigin(status.GitRemoteOrigin); ok {
-				branchURL := gp.BuildBranchURL(owner, repo, status.GitBranch)
-				if branchURL != "" {
-					result.URL = &branchURL
-				}
-			}
-		}
-	}
-	if status.PullRequestState.Valid {
-		pullRequestState := strings.TrimSpace(status.PullRequestState.String)
-		if pullRequestState != "" {
-			result.PullRequestState = &pullRequestState
-		}
-	}
-	result.PullRequestTitle = status.PullRequestTitle
-	result.PullRequestDraft = status.PullRequestDraft
-	result.ChangesRequested = status.ChangesRequested
-	result.Additions = status.Additions
-	result.Deletions = status.Deletions
-	result.ChangedFiles = status.ChangedFiles
-	if status.AuthorLogin.Valid {
-		result.AuthorLogin = &status.AuthorLogin.String
-	}
-	if status.AuthorAvatarUrl.Valid {
-		result.AuthorAvatarURL = &status.AuthorAvatarUrl.String
-	}
-	if status.BaseBranch.Valid {
-		result.BaseBranch = &status.BaseBranch.String
-	}
-	if status.HeadBranch.Valid {
-		result.HeadBranch = &status.HeadBranch.String
-	}
-	if status.PrNumber.Valid {
-		result.PRNumber = &status.PrNumber.Int32
-	}
-	if status.Commits.Valid {
-		result.Commits = &status.Commits.Int32
-	}
-	if status.Approved.Valid {
-		result.Approved = &status.Approved.Bool
-	}
-	if status.ReviewerCount.Valid {
-		result.ReviewerCount = &status.ReviewerCount.Int32
-	}
-	if status.RefreshedAt.Valid {
-		refreshedAt := status.RefreshedAt.Time
-		result.RefreshedAt = &refreshedAt
-	}
-	staleAt := status.StaleAt
-	result.StaleAt = &staleAt
-
-	return result
-}
-
 func (api *API) listChatProviders(rw http.ResponseWriter, r *http.Request) {
 	ctx := r.Context()
 	//nolint:gocritic // System context required to read enabled chat providers.

coderd/chats_test.go

@@ -19,6 +19,7 @@ import (
 	"github.com/coder/coder/v2/coderd/coderdtest"
 	"github.com/coder/coder/v2/coderd/coderdtest/oidctest"
 	"github.com/coder/coder/v2/coderd/database"
+	"github.com/coder/coder/v2/coderd/database/db2sdk"
 	"github.com/coder/coder/v2/coderd/database/dbauthz"
 	"github.com/coder/coder/v2/coderd/database/dbfake"
 	"github.com/coder/coder/v2/coderd/externalauth"
@@ -616,6 +617,127 @@ func TestWatchChats(t *testing.T) {
 		}
 	})
 
+	t.Run("DiffStatusChangeIncludesDiffStatus", func(t *testing.T) {
+		t.Parallel()
+
+		ctx := testutil.Context(t, testutil.WaitLong)
+		client, _, api := coderdtest.NewWithAPI(t, &coderdtest.Options{
+			DeploymentValues: chatDeploymentValues(t),
+		})
+		db := api.Database
+		user := coderdtest.CreateFirstUser(t, client)
+		modelConfig := createChatModelConfig(t, client)
+
+		// Insert a chat and a diff status row.
+		chat, err := db.InsertChat(dbauthz.AsSystemRestricted(ctx), database.InsertChatParams{
+			OwnerID:           user.UserID,
+			LastModelConfigID: modelConfig.ID,
+			Title:             "diff status watch test",
+		})
+		require.NoError(t, err)
+
+		refreshedAt := time.Now().UTC().Truncate(time.Second)
+		staleAt := refreshedAt.Add(time.Hour)
+		_, err = db.UpsertChatDiffStatusReference(
+			dbauthz.AsSystemRestricted(ctx),
+			database.UpsertChatDiffStatusReferenceParams{
+				ChatID:          chat.ID,
+				Url:             sql.NullString{String: "https://github.com/coder/coder/pull/99", Valid: true},
+				GitBranch:       "feature/test",
+				GitRemoteOrigin: "git@github.com:coder/coder.git",
+				StaleAt:         staleAt,
+			},
+		)
+		require.NoError(t, err)
+		_, err = db.UpsertChatDiffStatus(
+			dbauthz.AsSystemRestricted(ctx),
+			database.UpsertChatDiffStatusParams{
+				ChatID:           chat.ID,
+				Url:              sql.NullString{String: "https://github.com/coder/coder/pull/99", Valid: true},
+				PullRequestState: sql.NullString{String: "open", Valid: true},
+				Additions:        42,
+				Deletions:        7,
+				ChangedFiles:     5,
+				RefreshedAt:      refreshedAt,
+				StaleAt:          staleAt,
+			},
+		)
+		require.NoError(t, err)
+
+		// Open the watch WebSocket.
+		conn, err := client.Dial(ctx, "/api/experimental/chats/watch", nil)
+		require.NoError(t, err)
+		defer conn.Close(websocket.StatusNormalClosure, "done")
+
+		type watchEvent struct {
+			Type codersdk.ServerSentEventType `json:"type"`
+			Data json.RawMessage              `json:"data,omitempty"`
+		}
+
+		// Read the initial ping.
+		var ping watchEvent
+		err = wsjson.Read(ctx, conn, &ping)
+		require.NoError(t, err)
+		require.Equal(t, codersdk.ServerSentEventTypePing, ping.Type)
+
+		// Publish a diff_status_change event via pubsub,
+		// mimicking what PublishDiffStatusChange does after
+		// it reads the diff status from the DB.
+		dbStatus, err := db.GetChatDiffStatusByChatID(dbauthz.AsSystemRestricted(ctx), chat.ID)
+		require.NoError(t, err)
+		sdkDiffStatus := db2sdk.ChatDiffStatus(chat.ID, &dbStatus)
+		event := coderdpubsub.ChatEvent{
+			Kind: coderdpubsub.ChatEventKindDiffStatusChange,
+			Chat: codersdk.Chat{
+				ID:         chat.ID,
+				OwnerID:    chat.OwnerID,
+				Title:      chat.Title,
+				Status:     codersdk.ChatStatus(chat.Status),
+				CreatedAt:  chat.CreatedAt,
+				UpdatedAt:  chat.UpdatedAt,
+				DiffStatus: &sdkDiffStatus,
+			},
+		}
+		payload, err := json.Marshal(event)
+		require.NoError(t, err)
+		err = api.Pubsub.Publish(coderdpubsub.ChatEventChannel(user.UserID), payload)
+		require.NoError(t, err)
+
+		// Read events until we find the diff_status_change.
+		for {
+			var update watchEvent
+			err = wsjson.Read(ctx, conn, &update)
+			require.NoError(t, err)
+
+			if update.Type == codersdk.ServerSentEventTypePing {
+				continue
+			}
+			require.Equal(t, codersdk.ServerSentEventTypeData, update.Type)
+
+			var received coderdpubsub.ChatEvent
+			err = json.Unmarshal(update.Data, &received)
+			require.NoError(t, err)
+
+			if received.Kind != coderdpubsub.ChatEventKindDiffStatusChange ||
+				received.Chat.ID != chat.ID {
+				continue
+			}
+
+			// Verify the event carries the full DiffStatus.
+			require.NotNil(t, received.Chat.DiffStatus, "diff_status_change event must include DiffStatus")
+			ds := received.Chat.DiffStatus
+			require.Equal(t, chat.ID, ds.ChatID)
+			require.NotNil(t, ds.URL)
+			require.Equal(t, "https://github.com/coder/coder/pull/99", *ds.URL)
+			require.NotNil(t, ds.PullRequestState)
+			require.Equal(t, "open", *ds.PullRequestState)
+			require.EqualValues(t, 42, ds.Additions)
+			require.EqualValues(t, 7, ds.Deletions)
+			require.EqualValues(t, 5, ds.ChangedFiles)
+			break
+		}
+	})
+
 	t.Run("Unauthenticated", func(t *testing.T) {
 		t.Parallel()
 

coderd/database/db2sdk/db2sdk.go

@@ -21,6 +21,7 @@ import (
 	agentproto "github.com/coder/coder/v2/agent/proto"
 	"github.com/coder/coder/v2/coderd/chatd/chatprompt"
 	"github.com/coder/coder/v2/coderd/database"
+	"github.com/coder/coder/v2/coderd/externalauth/gitprovider"
 	"github.com/coder/coder/v2/coderd/rbac"
 	"github.com/coder/coder/v2/coderd/rbac/policy"
 	"github.com/coder/coder/v2/coderd/render"
@@ -1164,3 +1165,86 @@ func nullInt64Ptr(v sql.NullInt64) *int64 {
 	value := v.Int64
 	return &value
 }
+
+// ChatDiffStatus converts a database.ChatDiffStatus to a
+// codersdk.ChatDiffStatus. When status is nil an empty value
+// containing only the chatID is returned.
+func ChatDiffStatus(chatID uuid.UUID, status *database.ChatDiffStatus) codersdk.ChatDiffStatus {
+	result := codersdk.ChatDiffStatus{
+		ChatID: chatID,
+	}
+	if status == nil {
+		return result
+	}
+
+	result.ChatID = status.ChatID
+	if status.Url.Valid {
+		u := strings.TrimSpace(status.Url.String)
+		if u != "" {
+			result.URL = &u
+		}
+	}
+	if result.URL == nil {
+		// Try to build a branch URL from the stored origin.
+		// Since this function does not have access to the API
+		// instance, we construct a GitHub provider directly as
+		// a best-effort fallback.
+		// TODO: This uses the default github.com API base URL,
+		// so branch URLs for GitHub Enterprise instances will
+		// be incorrect. To fix this, this function would need
+		// access to the external auth configs.
+		gp := gitprovider.New("github", "", nil)
+		if gp != nil {
+			if owner, repo, _, ok := gp.ParseRepositoryOrigin(status.GitRemoteOrigin); ok {
+				branchURL := gp.BuildBranchURL(owner, repo, status.GitBranch)
+				if branchURL != "" {
+					result.URL = &branchURL
+				}
+			}
+		}
+	}
+	if status.PullRequestState.Valid {
+		pullRequestState := strings.TrimSpace(status.PullRequestState.String)
+		if pullRequestState != "" {
+			result.PullRequestState = &pullRequestState
+		}
+	}
+	result.PullRequestTitle = status.PullRequestTitle
+	result.PullRequestDraft = status.PullRequestDraft
+	result.ChangesRequested = status.ChangesRequested
+	result.Additions = status.Additions
+	result.Deletions = status.Deletions
+	result.ChangedFiles = status.ChangedFiles
+	if status.AuthorLogin.Valid {
+		result.AuthorLogin = &status.AuthorLogin.String
+	}
+	if status.AuthorAvatarUrl.Valid {
+		result.AuthorAvatarURL = &status.AuthorAvatarUrl.String
+	}
+	if status.BaseBranch.Valid {
+		result.BaseBranch = &status.BaseBranch.String
+	}
+	if status.HeadBranch.Valid {
+		result.HeadBranch = &status.HeadBranch.String
+	}
+	if status.PrNumber.Valid {
+		result.PRNumber = &status.PrNumber.Int32
+	}
+	if status.Commits.Valid {
+		result.Commits = &status.Commits.Int32
+	}
+	if status.Approved.Valid {
+		result.Approved = &status.Approved.Bool
+	}
+	if status.ReviewerCount.Valid {
+		result.ReviewerCount = &status.ReviewerCount.Int32
+	}
+	if status.RefreshedAt.Valid {
+		refreshedAt := status.RefreshedAt.Time
+		result.RefreshedAt = &refreshedAt
+	}
+	staleAt := status.StaleAt
+	result.StaleAt = &staleAt
+
+	return result
+}