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shopify-ai-backup/opencode/specs/09-session-page-hot-paths.md
2026-02-07 20:54:46 +00:00

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## Session hot paths
Reduce render work and duplication in `session.tsx`
---
### Summary
`packages/app/src/pages/session.tsx` mixes routing, commands, tab rendering, review panel wiring, terminal focus logic, and message scrolling. This spec targets hot-path performance + local code quality improvements that can ship together in one session-page-focused PR. It should follow the keyed command-registration pattern introduced in `packages/app/src/context/command.tsx`.
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### Goals
- Render heavy file-tab content only for the active tab
- Deduplicate review-panel wiring used in desktop and mobile paths
- Centralize terminal-focus DOM logic into one helper
- Reduce churn in command registration setup
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### Non-goals
- Scroll-spy rewrite (covered by `specs/04-scroll-spy-optimization.md`)
- Large routing/layout redesign
- Behavior changes to prompt submission or session history
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### Parallel execution contract
This spec owns:
- `packages/app/src/pages/session.tsx`
- New files under `packages/app/src/pages/session/*` (if extracted)
This spec should not modify:
- `packages/app/src/context/*`
- `packages/app/src/components/prompt-input.tsx`
- `packages/app/src/components/file-tree.tsx`
---
### Implementation plan
1. Add shared helpers for repeated session-page actions
- Extract `openReviewFile(path)` helper to replace repeated inline `onViewFile` bodies.
- Extract `focusTerminalById(id)` helper and reuse in both:
- terminal active change effect
- terminal drag-end focus restoration
2. Deduplicate review panel construction
- Build a shared review props factory (or local render helper) so desktop/mobile paths do not duplicate comment wiring, `onViewFile`, and classes glue.
- Keep per-surface differences limited to layout classes and diff style.
3. Gate heavy file-tab rendering by active tab
- Keep tab trigger list rendered for all opened tabs.
- Render `Tabs.Content` body only for `activeTab()`, plus lightweight placeholders as needed.
- Ensure per-tab scroll state restore still works when reactivating a tab.
4. Reduce command registry reallocation
- Register session commands with a stable key (`command.register("session", ...)`) so remounts replace prior session command entries.
- Move large command-array construction into smaller memoized blocks:
- stable command definitions
- dynamic state fields (`disabled`, titles) as narrow computed closures
- Keep command IDs, keybinds, and behavior identical.
---
### Acceptance criteria
- File tab bodies are not all mounted at once for large open-tab sets.
- `onViewFile` review behavior is defined in one shared helper.
- Terminal focus query/dispatch logic lives in one function and is reused.
- Session command registration uses a stable key (`"session"`) and `command.register` no longer contains one monolithic inline array with repeated inline handlers for shared actions.
- Session UX remains unchanged for:
- opening files from review
- drag-reordering terminal tabs
- keyboard command execution
---
### Validation plan
- Manual:
- Open 12+ file tabs, switch quickly, verify active tab restore and no blank states.
- Open review panel (desktop and mobile), use "view file" from diffs, verify same behavior as before.
- Drag terminal tab, ensure terminal input focus is restored.
- Run key commands: `mod+p`, `mod+w`, `mod+shift+r`, `ctrl+``.
- Perf sanity:
- Compare CPU usage while switching tabs with many opened files before/after.
---
### Risks and mitigations
- Risk: unmounted tab content loses transient editor state.
- Mitigation: keep persisted scroll/selection restore path intact and verify reactivation behavior.
- Risk: command refactor subtly changes command ordering.
- Mitigation: keep IDs and registration order stable, diff against current command list in dev.