---
id: "02-task-switch-regression-e2e"
title: "Task-switch cancellation regression"
status: done
wave: 2
depends_on: ["01-session-scoped-cancel-state"]
superseded_by: "06-cancel-reload-regression-e2e"
plan: "plan.md"
spec: "../../specs/ui/cancel-turn-progress.md"
---

# Task 02: Task-switch cancellation regression

> Historical implementation record. Holding the browser request proves only frontend-local state;
> Task 06 replaces this flow with backend-accepted task-switch, reload, and mobile regressions.

## Acceptance

- A WebSocket test controller can hold exactly one `agent.cancel` request, forward every unrelated
  frame, expose the held-request count, and release the request before teardown.
- The browser regression starts cancellation on task A, switches to task B, returns to task A, and
  observes the same disabled animated cancel state until release.
- Releasing the held request completes normal cancellation and leaves no held WebSocket request or
  stale progress entry at test end.

## Verification

```bash
(cd apps && pnpm install --frozen-lockfile)
(cd apps/web && pnpm e2e:run --host --project chromium -- tests/chat/cancel-progress-task-switch.spec.ts)
```

Follow TDD: add and run the browser regression against the pre-fix control to demonstrate that the
spinner disappears after the return navigation, then run it against Task 01's implementation.

## Files likely touched

- `apps/web/e2e/helpers/ws-drop.ts`
- `apps/web/e2e/tests/chat/cancel-progress-task-switch.spec.ts`

## Dependencies

Task 01.

## Parallelism

Sequential. This task validates Task 01's state ownership through the complete task-navigation flow.

## Inputs

- Spec: the pending-cancellation navigation scenario and persistence boundary.
- Plan: `E2E Tests` and `Mobile design contract`.
- Existing patterns: `routeMainWebSocketWithMessageAddResponseDrop` in `ws-drop.ts`,
  `SessionPage.clickTaskInSidebar`, and the task-switch flow in
  `apps/web/e2e/tests/session/multi-session-ux.spec.ts`.

## Output contract

Report the initial failing assertion, final Playwright result and discovered test count, held-frame
cleanup evidence, files changed, blockers or risks, and update this task plus `plan.md`
status/results in the same primary conversation.

## Results

- Initial regression evidence: the Task 01 remount test failed for both desktop and mobile before
  the store-backed state was implemented (`disabled` was `false` after remount instead of `true`).
- `cd apps && pnpm install --frozen-lockfile` — passed.
- `cd apps && pnpm --filter @kandev/web test -- --run lib/state/slices/ui/ui-slice.test.ts components/task/chat/chat-input-toolbar.test.tsx` — passed, 2 files / 52 tests.
- `cd apps/web && pnpm run typecheck` — passed.
- `cd apps/web && pnpm e2e:run --host --project chromium -- tests/chat/cancel-progress-task-switch.spec.ts` — passed, 1 test in 13.7s.
- The browser test observed one held `agent.cancel` request, verified the disabled loading control
  after returning to task A, released the request, and asserted the held count returned to zero and
  the idle composer resumed.
- Files changed: `apps/web/e2e/helpers/ws-drop.ts` and
  `apps/web/e2e/tests/chat/cancel-progress-task-switch.spec.ts`.
- No blockers or external side effects found.
- PR fixup commit `1bb1b2539` refined the held-count contract and isolated the component test's
  plugin-actions dependency; the focused unit, typecheck, lint, diff, and E2E checks passed again.