feat(web): persist model, thinking and fast mode in new threads

apps/web/src/components/ChatView.browser.tsx

@@ -750,6 +750,8 @@ describe("ChatView timeline estimator parity (full app)", () => {
       draftsByThreadId: {},
       draftThreadsByThreadId: {},
       projectDraftThreadIdByProjectId: {},
+      stickyModel: null,
+      stickyModelOptions: {},
     });
     useStore.setState({
       projects: [],
@@ -1277,6 +1279,134 @@ describe("ChatView timeline estimator parity (full app)", () => {
     }
   });
 
+  it("snapshots sticky codex settings into a new draft thread", async () => {
+    useComposerDraftStore.setState({
+      stickyModel: "gpt-5.3-codex",
+      stickyModelOptions: {
+        codex: {
+          reasoningEffort: "medium",
+          fastMode: true,
+        },
+      },
+    });
+
+    const mounted = await mountChatView({
+      viewport: DEFAULT_VIEWPORT,
+      snapshot: createSnapshotForTargetUser({
+        targetMessageId: "msg-user-sticky-codex-traits-test" as MessageId,
+        targetText: "sticky codex traits test",
+      }),
+    });
+
+    try {
+      const newThreadButton = page.getByTestId("new-thread-button");
+      await expect.element(newThreadButton).toBeInTheDocument();
+
+      await newThreadButton.click();
+
+      const newThreadPath = await waitForURL(
+        mounted.router,
+        (path) => UUID_ROUTE_RE.test(path),
+        "Route should have changed to a new draft thread UUID.",
+      );
+      const newThreadId = newThreadPath.slice(1) as ThreadId;
+
+      expect(useComposerDraftStore.getState().draftsByThreadId[newThreadId]).toMatchObject({
+        model: "gpt-5.3-codex",
+        effort: "medium",
+        codexFastMode: true,
+      });
+    } finally {
+      await mounted.cleanup();
+    }
+  });
+
+  it("falls back to defaults when no sticky composer settings exist", async () => {
+    const mounted = await mountChatView({
+      viewport: DEFAULT_VIEWPORT,
+      snapshot: createSnapshotForTargetUser({
+        targetMessageId: "msg-user-default-codex-traits-test" as MessageId,
+        targetText: "default codex traits test",
+      }),
+    });
+
+    try {
+      const newThreadButton = page.getByTestId("new-thread-button");
+      await expect.element(newThreadButton).toBeInTheDocument();
+
+      await newThreadButton.click();
+
+      const newThreadPath = await waitForURL(
+        mounted.router,
+        (path) => UUID_ROUTE_RE.test(path),
+        "Route should have changed to a new draft thread UUID.",
+      );
+      const newThreadId = newThreadPath.slice(1) as ThreadId;
+
+      expect(useComposerDraftStore.getState().draftsByThreadId[newThreadId]).toBeUndefined();
+    } finally {
+      await mounted.cleanup();
+    }
+  });
+
+  it("prefers draft state over sticky composer settings and defaults", async () => {
+    useComposerDraftStore.setState({
+      stickyModel: "gpt-5.3-codex",
+      stickyModelOptions: {
+        codex: {
+          reasoningEffort: "medium",
+          fastMode: true,
+        },
+      },
+    });
+
+    const mounted = await mountChatView({
+      viewport: DEFAULT_VIEWPORT,
+      snapshot: createSnapshotForTargetUser({
+        targetMessageId: "msg-user-draft-codex-traits-precedence-test" as MessageId,
+        targetText: "draft codex traits precedence test",
+      }),
+    });
+
+    try {
+      const newThreadButton = page.getByTestId("new-thread-button");
+      await expect.element(newThreadButton).toBeInTheDocument();
+
+      await newThreadButton.click();
+
+      const threadPath = await waitForURL(
+        mounted.router,
+        (path) => UUID_ROUTE_RE.test(path),
+        "Route should have changed to a sticky draft thread UUID.",
+      );
+      const threadId = threadPath.slice(1) as ThreadId;
+
+      expect(useComposerDraftStore.getState().draftsByThreadId[threadId]).toMatchObject({
+        model: "gpt-5.3-codex",
+        effort: "medium",
+        codexFastMode: true,
+      });
+
+      useComposerDraftStore.getState().setModel(threadId, "gpt-5.4");
+      useComposerDraftStore.getState().setEffort(threadId, "low");
+
+      await newThreadButton.click();
+
+      await waitForURL(
+        mounted.router,
+        (path) => path === threadPath,
+        "New-thread should reuse the existing project draft thread.",
+      );
+      expect(useComposerDraftStore.getState().draftsByThreadId[threadId]).toMatchObject({
+        model: "gpt-5.4",
+        effort: "low",
+        codexFastMode: true,
+      });
+    } finally {
+      await mounted.cleanup();
+    }
+  });
+
   it("creates a new thread from the global chat.new shortcut", async () => {
     const mounted = await mountChatView({
       viewport: DEFAULT_VIEWPORT,

apps/web/src/components/ChatView.tsx

@@ -224,6 +224,10 @@ export default function ChatView({ threadId }: ChatViewProps) {
   const setStoreThreadError = useStore((store) => store.setError);
   const setStoreThreadBranch = useStore((store) => store.setThreadBranch);
   const { settings } = useAppSettings();
+  const setStickyComposerModel = useComposerDraftStore((store) => store.setStickyModel);
+  const setStickyComposerModelOptions = useComposerDraftStore(
+    (store) => store.setStickyModelOptions,
+  );
   const timestampFormat = settings.timestampFormat;
   const navigate = useNavigate();
   const rawSearch = useSearch({
@@ -3048,11 +3052,12 @@ export default function ChatView({ threadId }: ChatViewProps) {
         scheduleComposerFocus();
         return;
       }
+      const resolvedModel = resolveAppModelSelection(provider, settings.customCodexModels, model);
       setComposerDraftProvider(activeThread.id, provider);
-      setComposerDraftModel(
-        activeThread.id,
-        resolveAppModelSelection(provider, settings.customCodexModels, model),
-      );
+      setComposerDraftModel(activeThread.id, resolvedModel);
+      if (provider === "codex") {
+        setStickyComposerModel(resolvedModel);
+      }
       scheduleComposerFocus();
     },
     [
@@ -3061,22 +3066,47 @@ export default function ChatView({ threadId }: ChatViewProps) {
       scheduleComposerFocus,
       setComposerDraftModel,
       setComposerDraftProvider,
+      setStickyComposerModel,
       settings.customCodexModels,
     ],
   );
   const onEffortSelect = useCallback(
     (effort: CodexReasoningEffort) => {
       setComposerDraftEffort(threadId, effort);
+      setStickyComposerModelOptions({
+        codex: {
+          reasoningEffort: effort,
+          ...(selectedCodexFastModeEnabled ? { fastMode: true } : {}),
+        },
+      });
       scheduleComposerFocus();
     },
-    [scheduleComposerFocus, setComposerDraftEffort, threadId],
+    [
+      scheduleComposerFocus,
+      selectedCodexFastModeEnabled,
+      setComposerDraftEffort,
+      setStickyComposerModelOptions,
+      threadId,
+    ],
   );
   const onCodexFastModeChange = useCallback(
     (enabled: boolean) => {
       setComposerDraftCodexFastMode(threadId, enabled);
+      setStickyComposerModelOptions({
+        codex: {
+          reasoningEffort: selectedEffort,
+          ...(enabled ? { fastMode: true } : {}),
+        },
+      });
       scheduleComposerFocus();
     },
-    [scheduleComposerFocus, setComposerDraftCodexFastMode, threadId],
+    [
+      scheduleComposerFocus,
+      selectedEffort,
+      setComposerDraftCodexFastMode,
+      setStickyComposerModelOptions,
+      threadId,
+    ],
   );
   const onEnvModeChange = useCallback(
     (mode: DraftThreadEnvMode) => {

apps/web/src/composerDraftStore.test.ts

@@ -59,17 +59,23 @@ function makeTerminalContext(input: {
   };
 }
 
+function resetComposerDraftStore() {
+  useComposerDraftStore.setState({
+    draftsByThreadId: {},
+    draftThreadsByThreadId: {},
+    projectDraftThreadIdByProjectId: {},
+    stickyModel: null,
+    stickyModelOptions: {},
+  });
+}
+
 describe("composerDraftStore addImages", () => {
   const threadId = ThreadId.makeUnsafe("thread-dedupe");
   let originalRevokeObjectUrl: typeof URL.revokeObjectURL;
   let revokeSpy: ReturnType<typeof vi.fn<(url: string) => void>>;
 
   beforeEach(() => {
-    useComposerDraftStore.setState({
-      draftsByThreadId: {},
-      draftThreadsByThreadId: {},
-      projectDraftThreadIdByProjectId: {},
-    });
+    resetComposerDraftStore();
     originalRevokeObjectUrl = URL.revokeObjectURL;
     revokeSpy = vi.fn();
     URL.revokeObjectURL = revokeSpy;
@@ -154,11 +160,7 @@ describe("composerDraftStore clearComposerContent", () => {
   let revokeSpy: ReturnType<typeof vi.fn<(url: string) => void>>;
 
   beforeEach(() => {
-    useComposerDraftStore.setState({
-      draftsByThreadId: {},
-      draftThreadsByThreadId: {},
-      projectDraftThreadIdByProjectId: {},
-    });
+    resetComposerDraftStore();
     originalRevokeObjectUrl = URL.revokeObjectURL;
     revokeSpy = vi.fn();
     URL.revokeObjectURL = revokeSpy;
@@ -332,11 +334,7 @@ describe("composerDraftStore project draft thread mapping", () => {
   const otherThreadId = ThreadId.makeUnsafe("thread-b");
 
   beforeEach(() => {
-    useComposerDraftStore.setState({
-      draftsByThreadId: {},
-      draftThreadsByThreadId: {},
-      projectDraftThreadIdByProjectId: {},
-    });
+    resetComposerDraftStore();
   });
 
   it("stores and reads project draft thread ids via actions", () => {
@@ -508,11 +506,7 @@ describe("composerDraftStore codex fast mode", () => {
   const threadId = ThreadId.makeUnsafe("thread-service-tier");
 
   beforeEach(() => {
-    useComposerDraftStore.setState({
-      draftsByThreadId: {},
-      draftThreadsByThreadId: {},
-      projectDraftThreadIdByProjectId: {},
-    });
+    resetComposerDraftStore();
   });
 
   it("stores codex fast mode in the draft", () => {
@@ -535,11 +529,7 @@ describe("composerDraftStore setModel", () => {
   const threadId = ThreadId.makeUnsafe("thread-model");
 
   beforeEach(() => {
-    useComposerDraftStore.setState({
-      draftsByThreadId: {},
-      draftThreadsByThreadId: {},
-      projectDraftThreadIdByProjectId: {},
-    });
+    resetComposerDraftStore();
   });
 
   it("keeps explicit DEFAULT_MODEL overrides instead of coercing to null", () => {
@@ -553,15 +543,51 @@ describe("composerDraftStore setModel", () => {
   });
 });
 
+describe("composerDraftStore sticky composer settings", () => {
+  beforeEach(() => {
+    resetComposerDraftStore();
+  });
+
+  it("stores sticky model and codex model options", () => {
+    const store = useComposerDraftStore.getState();
+
+    store.setStickyModel("gpt-5.3-codex");
+    store.setStickyModelOptions({
+      codex: {
+        reasoningEffort: "medium",
+        fastMode: true,
+      },
+    });
+
+    expect(useComposerDraftStore.getState()).toMatchObject({
+      stickyModel: "gpt-5.3-codex",
+      stickyModelOptions: {
+        codex: {
+          reasoningEffort: "medium",
+          fastMode: true,
+        },
+      },
+    });
+  });
+
+  it("normalizes empty sticky model options", () => {
+    const store = useComposerDraftStore.getState();
+
+    store.setStickyModelOptions({
+      codex: {
+        fastMode: false,
+      },
+    });
+
+    expect(useComposerDraftStore.getState().stickyModelOptions).toEqual({});
+  });
+});
+
 describe("composerDraftStore setProvider", () => {
   const threadId = ThreadId.makeUnsafe("thread-provider");
 
   beforeEach(() => {
-    useComposerDraftStore.setState({
-      draftsByThreadId: {},
-      draftThreadsByThreadId: {},
-      projectDraftThreadIdByProjectId: {},
-    });
+    resetComposerDraftStore();
   });
 
   it("persists provider-only selection even when prompt/model are empty", () => {
@@ -586,11 +612,7 @@ describe("composerDraftStore runtime and interaction settings", () => {
   const threadId = ThreadId.makeUnsafe("thread-settings");
 
   beforeEach(() => {
-    useComposerDraftStore.setState({
-      draftsByThreadId: {},
-      draftThreadsByThreadId: {},
-      projectDraftThreadIdByProjectId: {},
-    });
+    resetComposerDraftStore();
   });
 
   it("stores runtime mode overrides in the composer draft", () => {