feat(desktop): add favicons to the Browser panel

[chrisdeeming]

What Changed

Capture favicons from desktop preview sessions and show them in recently used sites and browser tabs, with the existing fallback when no captured icon is available.

Why

External favicon lookups cannot resolve local or private sites. Capturing the favicon from the browser keeps those icons accurate and available across sessions.

UI Changes

Recently used sites and browser tabs now show captured site favicons. Screenshots show the state before #5270 (history tracking) was merged, the state before the favicons are displayed, and the state after this PR is merged.

Before #5270	Before #5644	After #5644

Checklist

• This PR is small and focused
• I explained what changed and why
• I included before/after screenshots for any UI changes
• I included a video for animation/interaction changes

Prepared with GPT-5.6 Codex in T3 Code.

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Note

Medium Risk
Touches desktop preview navigation lifecycle and cross-process favicon fetch/rasterization; regressions could affect tab loading or icon display, but changes are largely isolated to preview/browser UI with broad test coverage.

Overview
Adds end-to-end favicon capture for the in-app browser: the desktop PreviewManager listens for page-favicon-updated, fetches/decodes/rasterizes candidates (with size, byte, and abort/race guards), and exposes favicon / faviconOrigin on preview tab state. Navigation, refresh, webview swap, and tab-close paths were tightened so loads are not blocked on pending navigations, superseded ERR_ABORTED navigations do not fail the UI, and stale captures cannot overwrite newer pages.

On the web side, a persisted browserFaviconStore keys icons by scoped project + canonical origin (collapsing localhost vs environment host), queues captures until the thread project/connection is ready, and wires PreviewFaviconIcon / tab chrome to prefer captured data URLs over Google’s s2 service—with expanded isPrivateNetworkHost so private/local origins never hit the public favicon provider.

^{Reviewed by Cursor Bugbot for commit c7d9f6e. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Add favicons to the Browser panel in the desktop preview

• Captures favicons from page loads in the desktop PreviewManager, normalizing them to bounded PNG data URLs (≤8192 bytes, ≤32px) with support for SVG/ICO rasterization via an isolated world and deduplication by content hash.
• Adds a persistent Zustand store (browserFaviconStore.ts) keyed by project and canonical host (with loopback/localhost collapsed to local), backed by localStorage with an in-memory fallback and a 40-entry eviction policy.
• Displays favicons in the Browser panel tab strip (RightPanelTabs) and empty-state cards (PreviewRecentUrlCard, PreviewLocalServerCard), preferring the captured data URL and falling back to the Google S2 favicon service for public hosts only.
• Skips the Google S2 fallback for private network hosts (loopback, RFC-1918, .local, .localhost, ts.net, bare hostnames, IPv4-mapped IPv6 private ranges).
• Favicons are invalidated on cross-document navigations, load failures, window opens, and webContents detach; publication is deferred until a successful navigation confirms the origin matches.
• Risk: favicon capture runs JavaScript in an isolated world per webContents and is serialized with a semaphore; timeouts guard each rasterization step, but failed captures are silently dropped rather than surfaced as errors.

^{Macroscope summarized c7d9f6e.}

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[macroscopeapp]

Approvability

Verdict: Needs human review

This PR introduces a substantial new feature (favicon display in Browser tabs) with ~1400 lines of new production code including complex async favicon capture/rasterization logic, a new persisted Zustand store, and UI components. New features introducing user-facing behavior warrant human review even when well-tested.

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[cursor]

Cursor Bugbot has reviewed your changes using high effort and found 1 potential issue.

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