feat(desktop): page zoom for embedded browser (#1333)

[Astro-Han]

Summary

First shippable slice of #1333: conversation-scoped page zoom for the embedded browser (WebContentsView), independent of app shell zoom.

• Overflow menu: Codex-style row Zoom + − / percent / + / circular reset
• Keyboard: Cmd/Ctrl +/-/0 while the embedded page is focused
• Wheel / pinch: zoom-changed on the page WebContents (sync + step fallback)
• Zoom lives on the per-conversation controller; navigation does not reset it; sessions do not share zoom
• Bounds still use window zoom only — panel geometry is unchanged

Why

Users cannot enlarge page content without resizing the whole app or changing OS display scale. Existing Cmd/Ctrl +/-/0 only zooms the app shell, not the embedded page. This is the P1 first slice of the embedded-browser completion umbrella.

Related Issue

Closes part of #1333 (page zoom only). Settings/full CDP, safe preview, and annotations remain follow-up PRs.

Human Review Status

Pending

Review Focus

1. Page zoom vs shell zoom isolation (setZoomFactor on the view’s WebContents only; computeViewBounds still uses window zoom).
2. Menu row UX: keeps menu open while stepping; reset is the circular control (percent is display-only).
3. Input routing: before-input-event on the page when focused; shell shortcuts unchanged when the page is not focused.
4. zoom-changed re-entrancy guard (applyingPageZoom) so programmatic setZoomFactor does not double-step.

Risk Notes

• Wheel/pinch behavior depends on Electron/Chromium zoom-changed semantics; both “factor already applied” and “direction request” paths are handled. macOS desktop walkthrough confirmed by maintainer.
• Visible UI change in the browser overflow menu; no new dependencies, permissions, or data migration.
• Conditional checklist: no release notes / credentials / deletion behavior changes.

How To Verify

packages/desktop-electron: bun test src/main/browser/logic.test.ts
  → 26 pass (page zoom clamp/step/reset + existing browser logic)

packages/desktop-electron: bun run typecheck
  → ok

packages/app: bun run typecheck
  → ok

packages/app: bun test src/i18n/parity.test.ts src/pages/session/browser
  → 25 pass

bun run dev:desktop (macOS)
  → maintainer confirmed: overflow Zoom row and page zoom look correct;
     shell chrome does not resize with page zoom

Screenshots or Recordings

Maintainer verified live in bun run dev:desktop on the PR branch (embedded browser overflow Zoom row + page zoom behavior).

Checklist

• Type label — enhancement
• Routing labels — app, ui, platform, desktop
• Priority label — P1
• Human Review Status above is set to Pending, Approved by @<reviewer>, or Not required: <reason> (default is Pending; "not required" is restricted to bot-authored low-risk PRs).
• I linked the related issue, or stated in Summary why there is no issue.
• I described the review focus and any meaningful risks.
• I replaced the example block in How To Verify with the real verification steps and the key result for each.
• I did not introduce unrelated refactors, dependencies, generated files, or file changes beyond the stated scope.
• (conditional) I manually checked visible UI or copy changes when needed, with screenshots or recordings. Leave unticked only if no visible UI or copy changed.
• (conditional) I considered macOS and Windows impact for platform, packaging, updater, signing, paths, shell, or permissions changes. Leave unticked only if no platform/packaging surface was touched.
• (conditional) I called out docs, release notes, dependencies, permissions, credentials, deletion behavior, generated content, or local file changes when relevant. Leave unticked only if none of those surfaces was touched.
• I reviewed the final diff for unrelated changes and suspicious dependency changes.
• I am targeting dev, and my PR title and commit messages use Conventional Commits in English.

Summary by CodeRabbit

• New Features

  • Added embedded page zoom controls with zoom in, zoom out, reset, and current zoom percentage display.
  • Added keyboard shortcuts for adjusting page zoom.
  • Zoom level now persists while navigating within a browser session.
  • Added English and Chinese translations for zoom controls.

• Bug Fixes

  • Prevented page zoom from exceeding supported limits or causing unintended menu behavior.
  • Removed conflicting browser zoom items from the desktop View menu.

[github-actions]

Suggested priority: P2 (includes user-path files (packages/app/src/context/platform.tsx, packages/app/src/i18n/en.ts, packages/app/src/i18n/zh.ts, packages/app/src/pages/session/browser/browser-panel.tsx, packages/desktop-electron/src/main/browser/controller.ts, packages/desktop-electron/src/main/browser/logic.test.ts, packages/desktop-electron/src/main/browser/logic.ts, packages/desktop-electron/src/main/ipc/browser.ts, packages/desktop-electron/src/preload/index.ts)).

P1/P0 are reserved for maintainer confirmation. Please relabel manually if this is a release blocker, security issue, data-loss risk, or updater/runtime failure.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

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Run ID: 422eb20e-1ad4-49f6-8969-86f923fa968c

📥 Commits

Reviewing files that changed from the base of the PR and between 7e889a9 and 9cecb75.

📒 Files selected for processing (6)

• packages/desktop-electron/src/main/browser/controller.ts
• packages/desktop-electron/src/main/browser/logic.test.ts
• packages/desktop-electron/src/main/browser/logic.ts
• packages/desktop-electron/src/main/menu-labels.ts
• packages/desktop-electron/src/main/menu-template.ts
• packages/desktop-electron/src/main/menu.test.ts

💤 Files with no reviewable changes (3)

• packages/desktop-electron/src/main/browser/logic.ts
• packages/desktop-electron/src/main/menu-labels.ts
• packages/desktop-electron/src/main/menu.test.ts

🚧 Files skipped from review as they are similar to previous changes (1)

• packages/desktop-electron/src/main/browser/controller.ts

---

📝 Walkthrough

Walkthrough

Adds embedded browser page zoom with clamped zoom math, per-conversation state, keyboard and menu controls, renderer-to-main IPC wiring, localized labels, and synchronization with Chromium WebContents.

Changes

Browser page zoom

Layer / File(s)	Summary
Zoom state and math packages/desktop-electron/src/main/browser/logic.ts, packages/desktop-electron/src/main/browser/logic.test.ts, packages/app/src/context/platform.tsx	Defines zoomFactor, zoom bounds, step/reset resolution, derived-state clamping, and corresponding tests.
Controller and IPC flow packages/desktop-electron/src/main/browser/controller.ts, packages/desktop-electron/src/main/ipc/browser.ts, packages/desktop-electron/src/preload/index.ts, packages/app/src/context/platform.tsx	Applies zoom to embedded WebContents, handles keyboard and Chromium zoom events, preserves state across navigation, and exposes target-based zoom actions through IPC.
Browser zoom controls packages/app/src/pages/session/browser/browser-panel.tsx, packages/app/src/i18n/en.ts, packages/app/src/i18n/zh.ts	Adds localized controls showing the current percentage with zoom-in, zoom-out, and reset actions.
Desktop menu cleanup packages/desktop-electron/src/main/menu-labels.ts, packages/desktop-electron/src/main/menu-template.ts, packages/desktop-electron/src/main/menu.test.ts	Removes legacy page-zoom menu roles and updates the View-menu localization expectations.

Estimated code review effort: 3 (Moderate) | ~30 minutes

Possibly related issues

• [Feature] Complete the embedded browser experience: zoom, settings, previews, and annotations #1333 — Covers the embedded-browser page-zoom functionality implemented by this change.

Possibly related PRs

• Astro-Han/pawwork#184 — Modifies the same desktop menu role-label plumbing used by the removed zoom roles.
• Astro-Han/pawwork#1221 — Modifies the same BrowserViewController area where page-zoom state and teardown updates are added.

Sequence Diagram(s)

sequenceDiagram
  participant BrowserPanel
  participant PreloadAPI
  participant BrowserIPC
  participant BrowserViewController
  participant WebContents
  BrowserPanel->>PreloadAPI: Request zoom action
  PreloadAPI->>BrowserIPC: Invoke browser:zoom
  BrowserIPC->>BrowserViewController: Forward target and action
  BrowserViewController->>WebContents: Set zoom factor
  WebContents-->>BrowserViewController: Emit zoom-changed
  BrowserViewController-->>BrowserPanel: Publish zoomFactor state

Loading

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 57.14% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title is concise and accurately summarizes the main change: embedded browser page zoom support.
Description check	✅ Passed	The description matches the template and includes all required sections, verification, screenshots, and a completed checklist.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/1333-browser-page-zoom

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[Astro-Han]

Follow-up (Occam pass)

Pushed 5c37cf67f7 after Codex/Pi first-principles review:

• Single truth: pageZoom only; zoom-changed only steps in/out from that value (no dual-source reconciliation with getZoomFactor).
• Reassert: setZoomFactor(pageZoom) on did-navigate and on display attach/claim so origin-scoped Chromium zoom cannot leave the page at 100% while the menu still shows the old percent. Geometry RAF ticks do not reassert every frame.
• Deleted: unused formatPageZoomPercent.
• Keyboard: allow Shift so Shift+= → zoom in on US layouts.
• Pinch: still not enabled. Electron visual pinch is a second scale (off by default); turning it on without owning it would lie in the menu percent. Wheel + menu + shortcuts remain the solid paths; true pinch is a follow-up if we want a honest owned path.

Contract residual: same-origin zoom is partition-scoped in Chromium. Reassert on show/navigate is the smallest fix without splitting the shared login partition.

[Astro-Han]

Contract + menu cleanup

Pushed after first-principles re-review:

• Removed View menu zoomIn / zoomOut / resetZoom (macOS + Windows). Shell zoom is already pinned to 1; those roles only stole keyboard accelerators from the embedded page before-input-event path.
• Page zoom surface remains the browser overflow menu (− / percent / + / reset) + focused-page shortcuts + wheel.
• Deferred / residual (documented, not coded):
  • Trackpad pinch: Electron visual zoom is a second scale; left off so menu % stays honest.
  • Same-origin multi-session simultaneous zoom: Chromium HostZoomMap in the shared login partition; reassert on navigate/display covers sequential use. No partition split.

Please re-check on macOS: page focused → ⌘= / ⌘- / ⌘0 all step page zoom only.