feat: centralised getEffectiveCwd() + provider helpers with stale session guard

[yoziv]

Summary

Follow-up to #112 — addresses both pieces of @InbarR's review feedback on the original draft, now that #112 has merged.

1. Stale session guard (unchanged from prior revision)

getEffectiveCwd() only prefers the AI session's CWD when the session is active (status !== 'idle'). After the CLI exits and the session goes idle, the helper falls back to the shell's CWD — preventing the diff panel from showing the wrong repo.

2. Centralised helpers (now actually applied across the codebase)

Three exported helpers live in src/renderer/state/terminal-store.ts:

• findSessionById(copilotSessions, claudeCodeSessions, id) — replaces the duplicated cs.find(...) ?? ccs.find(...) pattern.
• getSessionProvider(copilotSessions, claudeCodeSessions, id) — returns 'copilot' \| 'claude-code' \| undefined for sites that only need the provider tag (replaces .some() duplicates).
• getEffectiveCwd(terminal, copilotSessions, claudeCodeSessions) — single source of truth for where is this terminal working?

When a third AI provider is added, only these helpers need updating.

3. e2e test no longer relies on require() in the renderer

The previous spec used require('../src/renderer/state/terminal-store') inside window.evaluate(). Electron's renderer is a sandboxed browser context with no CommonJS require, so the call threw before the typeof fallback could run and the test silently failed on CI.

App.tsx now exposes __getEffectiveCwd, __findSessionById, and __getSessionProvider on window alongside __terminalStore, and the spec calls the real helpers directly. The inline fallback is gone — the test now actually exercises production code.

Changes

File	Change
src/renderer/state/terminal-store.ts	Added findSessionById, getSessionProvider, getEffectiveCwd; migrated 4 internal sites
src/renderer/App.tsx	Exposed the three helpers on window for e2e
src/renderer/components/DiffReview.tsx	Uses getEffectiveCwd + getSessionProvider
src/renderer/components/StatusBar.tsx	2 sites migrated to findSessionById
src/renderer/components/TabBar.tsx	aiStatus selector migrated
src/renderer/components/TerminalPanel.tsx	4 selectors migrated (latestPrompt, latestPromptTime, sessionStatus, aiProvider)
tests/e2e/effective-cwd-helper.spec.ts	Drops require() + inline fallback; calls the real helper via window

Net -28 lines across renderer code, no behaviour change for the migrated sites (IDs are unique across the provider arrays, so the lookup-order swap is semantically equivalent).

Test coverage

Scenario	Expected CWD	Test
Active AI session linked	AI session CWD	✅
Idle AI session linked (stale)	Shell CWD (fallback)	✅
No AI session linked	Shell CWD	✅
Stale aiSessionId (session removed)	Shell CWD (fallback)	✅

Dependencies

Now rebased on top of merged #112. No outstanding chain.

[InbarR]

Direction is good - having a single source of truth for the effective CWD makes sense, especially with the idle-session guard.

Two things before merging:

1. The new e2e spec (effective-cwd-helper.spec.ts) fails on CI because it uses require(...) inside a browser context, and browsers don't have CommonJS require. The typeof getEffectiveCwd === 'function' fallback never runs because require throws first. Easiest fix is a top-level ES import, or expose the helper on window from the renderer for e2e access.

2. The PR description mentions ~10 call sites being migrated, but only DiffReview.tsx is converted in this diff. Are the rest planned for a follow-up?

The other Playwright failures look like the same pre-existing base-branch issue I noted on #112, not anything you introduced.

Suggest landing #112 first since this one builds on it, then this rebases cleanly.

[yoziv]

Both points addressed in the latest push:

1. tests/e2e/effective-cwd-helper.spec.ts no longer uses require(). The renderer's helpers are now exposed on window from App.tsx (same pattern as __terminalStore), and the spec calls window.__getEffectiveCwd(...) directly — the test now exercises the real production code instead of the inline fallback.

2. The ~10 call sites are migrated in this PR (not deferred). findSessionById covers session-object lookups; added a small sibling getSessionProvider() for the .some || .some sites that only want the provider tag. Sites converted: 4 internal in terminal-store.ts, plus StatusBar, TabBar, TerminalPanel (4 selectors) and DiffReview. Net -28 lines.

Also rebased on top of merged #112 (one trivial conflict in DiffReview.tsx resolved by keeping the centralised version).