fix(sessions): name tasks from pasted text-file contents (#2850)

## Problem

When you paste a prompt into PHCode it gets auto-converted to a `pasted-text.txt` attachment with **no typed text**, so the only signal for naming the task is the file's contents. The name generator wasn't reading them, so the task defaulted to **Untitled**.

Tracing the flow, the breakage is **specific to cloud tasks**:

- **Local tasks already work** — the prompt event carries the `<file path="…"/>` tag inline, which the title generator reads.
- **Cloud tasks were broken** — by the time the generator runs, the original local path is gone:
    - the stored description is reduced to `Attached files: pasted-text.txt` (no path), and
    - the echoed prompt event points at the **remote sandbox path** (`file:///workspace/.posthog/attachments/…`), which can't be read on the user's machine.

The local path only exists at **submit time**, before the file is uploaded as a cloud artifact — so the generator had only the filename and produced `Untitled`.



Closes GROW-47

## Fix

1. **`titleAttachmentStore.ts`** (new) — small UI store that stashes the prompt's local attachment paths keyed by task id.
2. **`useTaskCreation.ts`** — on task creation, stash those local paths for the new task id.
3. **`useChatTitleGenerator.ts`** — read the stashed paths, hand them to the title generator, and clear them once a title is produced.
4. **`titleGeneratorService.ts`** — widened the `Attached files:` matcher so the `1. [Attached files: …]` form (produced when titling from prompts) is recognized as "no real text", falling through to the file contents.

The generator already truncates to 500 chars, skips binary files, and **ignores attachments when real text is typed** — so normal prompts are unaffected. This also makes the local path more robust (it now gets the explicit path too).

## Tests

- `titleGeneratorService.test.ts` — cases for the cloud description form (`Attached files: …`) and the numbered prompt-list form, plus a guard that typed text still wins over attachments.
- `useChatTitleGenerator.test.ts` — a cloud-style case asserting stashed local paths are passed through and cleared after naming; updated existing assertions for the new arg.

## Verification

Typecheck, Biome lint (incl. `noRestrictedImports`), and a full `pnpm build` pass; sessions + task-detail suites green (435 tests). Did **not** run a live cloud end-to-end (needs auth + cloud backend + a real LLM call) — covered by unit tests instead.

## Known limitation

If the app reloads in the few seconds between submitting and the title generating, the in-memory stash is lost and the title falls back to the attachment summary (same as other in-memory optimistic state). Can persist it if desired.

Author: fercgomes

packages/core/src/sessions/titleGeneratorService.test.ts

@@ -86,6 +86,53 @@ describe("enrichDescriptionWithFileContent", () => {
     },
   );
 
+  it.each([
+    {
+      label: "cloud description summary",
+      description: "Attached files: pasted-text.txt",
+    },
+    {
+      label: "numbered prompt list item",
+      description: "1. [Attached files: pasted-text.txt]",
+    },
+  ])(
+    "reads explicit file paths for attachment-only prompt -- $label",
+    async ({ description }) => {
+      readAbsoluteFile.mockResolvedValue(
+        "Refactor the auth flow and add tests",
+      );
+      const result = await makeService().enrichDescriptionWithFileContent(
+        description,
+        ["/tmp/clip/pasted-text.txt"],
+      );
+      expect(result).toBe("Refactor the auth flow and add tests");
+      expect(readAbsoluteFile).toHaveBeenCalledWith(
+        "/tmp/clip/pasted-text.txt",
+      );
+    },
+  );
+
+  it("ignores explicit file paths when the prompt has real typed text", async () => {
+    const description = "Fix the login bug\n\nAttached files: pasted-text.txt";
+    const result = await makeService().enrichDescriptionWithFileContent(
+      description,
+      ["/tmp/clip/pasted-text.txt"],
+    );
+    expect(result).toBe(description);
+    expect(readAbsoluteFile).not.toHaveBeenCalled();
+  });
+
+  it("does not strip user text that starts with 'Attached files:' but has no brackets", async () => {
+    // "1. Attached files: xyz" (no brackets) is user-typed text, not a sentinel.
+    const description = "1. Attached files: here is my task\n2. please fix it";
+    const result = await makeService().enrichDescriptionWithFileContent(
+      description,
+      ["/tmp/clip/pasted-text.txt"],
+    );
+    expect(result).toBe(description);
+    expect(readAbsoluteFile).not.toHaveBeenCalled();
+  });
+
   it("truncates content longer than 500 chars", async () => {
     const longContent = "x".repeat(600);
     readAbsoluteFile.mockResolvedValue(longContent);

packages/core/src/sessions/titleGeneratorService.ts

@@ -13,7 +13,15 @@ import {
   type TitleGeneratorLogger,
 } from "./titleGeneratorIdentifiers";
 
-const ATTACHED_FILES_REGEX = /^\[?Attached files:.*]?$/gm;
+// Matches the attachment-summary sentinel we synthesize for prompts that carry
+// no typed text. Three forms need stripping:
+//   "Attached files: a.txt"          — bare description (cloud task.description)
+//   "[Attached files: a.txt]"        — bracketed session-event sentinel
+//   "1. [Attached files: a.txt]"     — numbered form from formatPromptsForTitleInput
+// The bracketed forms require a literal `[` so that user text like
+// "1. Attached files: my notes" (no brackets) is never stripped.
+const ATTACHED_FILES_REGEX =
+  /^(?:(?:\d+\.\s*)?\[Attached files:[^\]]*\]|Attached files:.*)$/gm;
 const PASTED_TEXT_SNIPPET_LIMIT = 500;
 
 const SYSTEM_PROMPT = `You are a title and summary generator. Output using exactly this format:

packages/ui/src/features/sessions/hooks/useChatTitleGenerator.test.ts

@@ -14,6 +14,8 @@ const mockSetQueryData = vi.hoisted(() => vi.fn());
 const mockUpdateSessionTaskTitle = vi.hoisted(() => vi.fn());
 const mockPrompts = vi.hoisted(() => ({ value: [] as string[] }));
 const mockSessionStoreSetters = vi.hoisted(() => ({ updateSession: vi.fn() }));
+const mockTitleAttachmentPaths = vi.hoisted(() => ({ value: [] as string[] }));
+const mockTitleAttachmentClear = vi.hoisted(() => vi.fn());
 
 vi.mock("@tanstack/react-query", () => ({
   useQueryClient: () => ({
@@ -64,6 +66,14 @@ vi.mock("@posthog/ui/shell/logger", () => ({
   },
 }));
 
+vi.mock("@posthog/ui/shell/titleAttachmentStore", () => ({
+  titleAttachmentStoreApi: {
+    get: () => mockTitleAttachmentPaths.value,
+    set: vi.fn(),
+    clear: mockTitleAttachmentClear,
+  },
+}));
+
 vi.mock("@posthog/ui/features/sessions/sessionStore", () => {
   const state = {
     taskIdIndex: { "task-1": "run-1" },
@@ -108,6 +118,7 @@ describe("useChatTitleGenerator", () => {
     vi.clearAllMocks();
     mockIsAuthenticated.value = true;
     mockPrompts.value = [];
+    mockTitleAttachmentPaths.value = [];
     mockEnrichDescription.mockImplementation((desc: string) =>
       Promise.resolve(desc),
     );
@@ -130,7 +141,10 @@ describe("useChatTitleGenerator", () => {
     renderHook(() => useChatTitleGenerator(createTask()));
 
     await waitFor(() => {
-      expect(mockEnrichDescription).toHaveBeenCalledWith("Fix the login bug");
+      expect(mockEnrichDescription).toHaveBeenCalledWith(
+        "Fix the login bug",
+        [],
+      );
     });
     await waitFor(() => {
       expect(mockUpdateTask).toHaveBeenCalledWith(TASK_ID, {
@@ -266,11 +280,64 @@ describe("useChatTitleGenerator", () => {
     await waitFor(() => {
       expect(mockEnrichDescription).toHaveBeenCalledWith(
         '1. <file path="/tmp/code.ts" />',
+        [],
       );
       expect(mockGenerateTitle).toHaveBeenCalledWith("enriched content");
     });
   });
 
+  it("passes stashed local attachment paths and clears them after naming", async () => {
+    mockTitleAttachmentPaths.value = ["/tmp/clip/pasted-text.txt"];
+    mockEnrichDescription.mockResolvedValue("Refactor the auth flow");
+    mockGenerateTitle.mockResolvedValue({
+      title: "Refactor auth flow",
+      summary: "",
+    });
+    mockPrompts.value = ["[Attached files: pasted-text.txt]"];
+
+    renderHook(() =>
+      useChatTitleGenerator(
+        createTask({
+          title: "",
+          description: "Attached files: pasted-text.txt",
+        }),
+      ),
+    );
+
+    await waitFor(() => {
+      expect(mockEnrichDescription).toHaveBeenCalledWith(
+        "1. [Attached files: pasted-text.txt]",
+        ["/tmp/clip/pasted-text.txt"],
+      );
+    });
+    await waitFor(() => {
+      expect(mockUpdateTask).toHaveBeenCalledWith(TASK_ID, {
+        title: "Refactor auth flow",
+      });
+    });
+    expect(mockTitleAttachmentClear).toHaveBeenCalledWith(TASK_ID);
+  });
+
+  it("does not clear stashed paths when generation returns null (keeps them for prompt-path retry)", async () => {
+    mockTitleAttachmentPaths.value = ["/tmp/clip/pasted-text.txt"];
+    mockGenerateTitle.mockResolvedValue(null);
+    mockPrompts.value = ["[Attached files: pasted-text.txt]"];
+
+    renderHook(() =>
+      useChatTitleGenerator(
+        createTask({
+          title: "",
+          description: "Attached files: pasted-text.txt",
+        }),
+      ),
+    );
+
+    await waitFor(() => {
+      expect(mockGenerateTitle).toHaveBeenCalled();
+    });
+    expect(mockTitleAttachmentClear).not.toHaveBeenCalled();
+  });
+
   it("updates conversation summary when returned", async () => {
     mockGenerateTitle.mockResolvedValue({
       title: "Some title",

packages/ui/src/features/sessions/hooks/useChatTitleGenerator.ts

@@ -20,6 +20,7 @@ import {
 } from "@posthog/ui/features/sessions/sessionStore";
 import { taskKeys } from "@posthog/ui/features/tasks/taskKeys";
 import { logger } from "@posthog/ui/shell/logger";
+import { titleAttachmentStoreApi } from "@posthog/ui/shell/titleAttachmentStore";
 import { type QueryClient, useQueryClient } from "@tanstack/react-query";
 import { useEffect, useRef } from "react";
 
@@ -95,10 +96,18 @@ export function useChatTitleGenerator(task: Task): void {
 
     const run = async () => {
       try {
-        const content =
-          await titleGenerator.enrichDescriptionWithFileContent(rawContent);
+        const attachmentPaths = titleAttachmentStoreApi.get(taskId) ?? [];
+        const content = await titleGenerator.enrichDescriptionWithFileContent(
+          rawContent,
+          attachmentPaths,
+        );
         const result = await titleGenerator.generateTitleAndSummary(content);
         if (result) {
+          // Drop the stash once a title has been successfully produced so the
+          // map doesn't grow across a long-lived session. Keeping it on failure
+          // lets the prompt-based regeneration at REGENERATE_INTERVAL pick it
+          // up and try again with the file contents.
+          titleAttachmentStoreApi.clear(taskId);
           const { title, summary } = result;
           const titleLocked = isAutoTitleLocked(
             getCachedTask(queryClient, taskId) ?? task,

packages/ui/src/features/task-detail/hooks/useTaskCreation.ts

@@ -26,6 +26,7 @@ import { toast } from "../../../primitives/toast";
 import { track } from "../../../shell/analytics";
 import { logger } from "../../../shell/logger";
 import { pendingTaskPromptStoreApi } from "../../../shell/pendingTaskPromptStore";
+import { titleAttachmentStoreApi } from "../../../shell/titleAttachmentStore";
 import { useAuthStateValue } from "../../auth/store";
 import { assertCloudUsageAvailable } from "../../billing/preflightCloudUsage";
 import { useUsageLimitStore } from "../../billing/usageLimitStore";
@@ -318,6 +319,24 @@ export function useTaskCreation({
           input,
           (output) => {
             invalidateTasks(output.task);
+            // Stash the prompt's local attachment paths so the chat-title
+            // generator can read their contents when naming the task — needed
+            // for pasted-text prompts whose only signal is the file body, and
+            // especially for cloud tasks where the local path is otherwise lost
+            // once the file is uploaded as an artifact.
+            // Exclude folder chips — only file paths are readable by the title
+            // generator's readAbsoluteFile call.
+            const folderIds = new Set(
+              content.segments.flatMap((seg) =>
+                seg.type === "chip" && seg.chip.type === "folder"
+                  ? [seg.chip.id]
+                  : [],
+              ),
+            );
+            const fileOnlyPaths = filePaths.filter((p) => !folderIds.has(p));
+            if (fileOnlyPaths.length > 0) {
+              titleAttachmentStoreApi.set(output.task.id, fileOnlyPaths);
+            }
             if (signalReportId) {
               clearTaskInputReportAssociation();
             }

packages/ui/src/shell/titleAttachmentStore.ts

@@ -0,0 +1,48 @@
+import { create } from "zustand";
+
+/**
+ * Local attachment file paths captured at task-creation time, keyed by task id,
+ * so the chat-title generator can read their contents when naming a task.
+ *
+ * Why this exists: when a prompt is pasted as a text file (or otherwise sent as
+ * an attachment with no typed text), the title has to come from the file's
+ * contents. For local tasks the prompt event still carries the `<file .../>`
+ * path, so the generator can read it directly. For cloud tasks it cannot — the
+ * stored description is reduced to `Attached files: <name>` and the echoed
+ * prompt event points at the remote sandbox path (e.g.
+ * `file:///workspace/.posthog/attachments/...`), which is not readable on the
+ * user's machine. The only place the original local path exists is at submit
+ * time, so we stash it here and hand it to the generator, which reads the file
+ * locally before it is cleaned up.
+ *
+ * Best-effort and in-memory: lost on reload, at which point the title falls back
+ * to the attachment summary.
+ */
+interface TitleAttachmentStore {
+  byTaskId: Record<string, string[]>;
+  set: (taskId: string, filePaths: string[]) => void;
+  get: (taskId: string) => string[] | undefined;
+  clear: (taskId: string) => void;
+}
+
+const useTitleAttachmentStore = create<TitleAttachmentStore>((set, get) => ({
+  byTaskId: {},
+  set: (taskId, filePaths) =>
+    set((state) => ({
+      byTaskId: { ...state.byTaskId, [taskId]: filePaths },
+    })),
+  get: (taskId) => get().byTaskId[taskId],
+  clear: (taskId) =>
+    set((state) => {
+      if (!(taskId in state.byTaskId)) return state;
+      const { [taskId]: _removed, ...rest } = state.byTaskId;
+      return { byTaskId: rest };
+    }),
+}));
+
+export const titleAttachmentStoreApi = {
+  set: (taskId: string, filePaths: string[]) =>
+    useTitleAttachmentStore.getState().set(taskId, filePaths),
+  get: (taskId: string) => useTitleAttachmentStore.getState().get(taskId),
+  clear: (taskId: string) => useTitleAttachmentStore.getState().clear(taskId),
+};