feat(server): expand project favicon resolution with PWA manifest and directory scan

[Brechard]

Closes #4636

What Changed

Two new resolution stages in ProjectFaviconResolver, both framework-agnostic and both tried only after every existing check fails:

1. PWA manifests — parses manifest.json, public/manifest.json, site.webmanifest and public/site.webmanifest, resolving each icons[].src on disk and preferring the largest declared sizes.
2. Directory scan fallback — walks common asset folders (public, app, src, src/app, assets, src/assets, assets/icons, assets/icon, static, resources, images, img, media, app-icon, .idea) for well-known basenames (favicon, icon, logo, apple-touch-icon, app-icon, brand, app), picking by directory → name → extension priority.

ProjectFaviconResolutionError gains read-manifest and scan-directory operations. Paths stay guarded inside the workspace root.

Why

The resolver is good at React-shaped repos and falls back to the generic folder glyph for almost everything else. That's the complaint in #4304 ("works well for React projects and poorly for others"), #1020 and #4935, and it's what the reporter on #2561 pushed back with after it was closed: "auto detect doesn't work for most projects, for example BE, cli databases or some specific monorepos."

The two stages here are deliberately not per-framework. A Flutter app is the motivating case: no package.json, no index.html, icon at assets/icons/icon.png referenced only from flutter_launcher_icons.yaml. Nothing in the current resolver — or in any of the open favicon PRs — finds it, but a prioritized scan of asset directories does, and the same scan covers Android, Go, Rust, CLI and backend repos without teaching the resolver about any of them.

How this differs from the other open favicon PRs

These are complementary, not competing — each works a different axis:

• fix: resolve Svelte(Kit) favicons #4448 (Svelte paths) and the closed fix: add svelte-specific favicon candidates to the resolver #1613 add framework-specific candidates. This PR is the general form of that approach: the directory scan subsumes per-framework path lists, so ecosystems nobody has filed a PR for still resolve.
• fix(server): resolve monorepo favicons and sanitize SVGs #4424 (monorepo workspaces) searches other roots — apps/*, packages/*, services/*. This PR searches the selected root more thoroughly. Orthogonal; both can land, and this one does not close monorepo projects do not resolve nested app favicons #1020.
• feat: serve stack-specific default project favicons #3854 (stack-specific defaults) substitutes a stock framework logo when nothing is found. This PR finds the project's own icon, so it reduces how often that fallback is reached. A repo that has an icon should show it rather than a Next.js logo.
• Refresh a project favicon when its icon is clicked #4337 (refresh on click) is cache invalidation for an already-resolved URL. No overlap.

Note on custom icons

t3.json already supports iconPath and it is checked before everything here, so a project that wants an explicit icon has an escape hatch today. This PR only changes what happens when nothing is declared.

Verification

• npx vitest run src/project/ProjectFaviconResolver.test.ts — 20/20 pass, covering manifest selection, multi-size strings, scan priority ordering, unreadable directories, permission failures, and manifest→scan fallback.
• npx tsc --noEmit clean.
• Built and installed the desktop app; verified against real repos including a Flutter project that previously showed the folder glyph.

Additive behind the same resolvePath API, and the added filesystem reads only happen on the path that currently returns null. Cursor Bugbot reviewed 709dbde as Low Risk.

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[cursor]

Cursor Bugbot has reviewed your changes using high effort and found 3 potential issues.

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[macroscopeapp]

Approvability

Verdict: Needs human review

3 blocking correctness issues found. This PR introduces significant new capability (PWA manifest parsing and directory scanning for favicon resolution) with 396 lines of new code. New features that add user-facing behavior warrant human review. Additionally, there are unresolved review comments identifying potential bugs in the new logic.

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[t3dotgg]

Note

🤖 GPT-5.6 Sol responding on behalf of Theo

We're closing this PR as we clean up the T3 Code backlog. Thank you for taking the time to put this together.

This adds PWA manifest parsing and a broad directory scan with many filename, extension, folder, and priority rules for favicon discovery. #4424 provides a narrower monorepo favicon repair without the general repository scan.

If you believe we closed this in error, please reopen the PR and leave a comment explaining what we missed.