[kngsly]

Fixes

• Duplicate session/tab creation on project open. Opening a project from Get started created 4 sessions and 9 chat tabs and logged 6 "Orphaned session tabs recovered" warnings (reproduced in a production bundle, not a StrictMode artifact). The first-session and first-tab effects re-ran on every render while the create was in flight; both are now single-flight.
• Chat tabs were never bound to their chat session. renderPanel matched tabs by t.id === panel.id, which never holds for backend tab ids, so onChatSessionCreated never found the tab: tabs stayed chatSessionId = null (orphan warnings) and prompts queued for a new chat were never delivered. Panels now record their backing tab and bind it whichever of tab/session finishes first.

UX

• Empty chat shows three starters (Describe this project /schematic, Generate ideas /idea generate, Plan before editing /plan on). en + zh-CN, zh-TW regenerated.
• Composer controls no longer overlap in narrow panels (container query on the composer; only the model chip shrinks).
• Sidebar update CTA fits its footer; label is now "Restart to update".
• "Generating ideas…" notice clears when the run settles instead of staying after a setup error.
• Mock check_for_updates returns the full UpdateInfo shape (a production mock bundle crashed on policy.mandatory).

Verification

• npx tsc --noEmit, npm run build, check:ui-invariants, check:i18n
• npm run test:e2e: 566 passed, 3 skipped
• New first-open-chat.spec.ts fails on main, passes here.
• Visual check in the mocked renderer at 1280×800 and 960×640 (two chats side by side). Not yet checked in a tauri dev window.