test(app): deflake slash terminal toggle flow (#17881)

packages/app/e2e/AGENTS.md

@@ -174,6 +174,8 @@ await page.keyboard.press(`${modKey}+Comma`) // Open settings
 - In terminal tests, type through the browser. Do not write to the PTY through the SDK.
 - Use `waitTerminalReady(page, { term? })` and `runTerminal(page, { cmd, token, term?, timeout? })` from `actions.ts`.
 - These helpers use the fixture-enabled test-only terminal driver and wait for output after the terminal writer settles.
+- After opening the terminal, use `waitTerminalFocusIdle(...)` before the next keyboard action when prompt focus or keyboard routing matters.
+- This avoids racing terminal mount, focus handoff, and prompt readiness when the next step types or sends shortcuts.
 - Avoid `waitForTimeout` and custom DOM or `data-*` readiness checks.
 
 ### Wait on state
@@ -182,6 +184,9 @@ await page.keyboard.press(`${modKey}+Comma`) // Open settings
 - Avoid race-prone flows that assume work is finished after an action
 - Wait or poll on observable state with `expect(...)`, `expect.poll(...)`, or existing helpers
 - Prefer locator assertions like `toBeVisible()`, `toHaveCount(0)`, and `toHaveAttribute(...)` for normal UI state, and reserve `expect.poll(...)` for probe, mock, or backend state
+- Prefer semantic app state over transient DOM visibility when behavior depends on active selection, focus ownership, or async retry loops
+- Do not treat a visible element as proof that the app will route the next action to it
+- When fixing a flake, validate with `--repeat-each` and multiple workers when practical
 
 ### Add hooks
 
@@ -189,11 +194,16 @@ await page.keyboard.press(`${modKey}+Comma`) // Open settings
 - Keep these hooks minimal and purpose-built, following the style of `packages/app/src/testing/terminal.ts`
 - Test-only hooks must be inert unless explicitly enabled; do not add normal-runtime listeners, reactive subscriptions, or per-update allocations for e2e ceremony
 - When mocking routes or APIs, expose explicit mock state and wait on that before asserting post-action UI
+- Add minimal test-only probes for semantic state like the active list item or selected command when DOM intermediates are unstable
+- Prefer probing committed app state over asserting on transient highlight, visibility, or animation states
 
 ### Prefer helpers
 
 - Prefer fluent helpers and drivers when they make intent obvious and reduce locator-heavy noise
 - Use direct locators when the interaction is simple and a helper would not add clarity
+- Prefer helpers that both perform an action and verify the app consumed it
+- Avoid composing helpers redundantly when one already includes the other or already waits for the resulting state
+- If a helper already covers the required wait or verification, use it directly instead of layering extra clicks, keypresses, or assertions
 
 ## Writing New Tests