fix: delay ObjectURL revocation to prevent failed downloads

[hobostay]

Summary

• Delay URL.revokeObjectURL from 0ms to 1000ms in frame capture download
• setTimeout(..., 0) revokes the blob URL before the browser initiates the download, causing empty/failed downloads

Details

Affected file: packages/studio/src/App.tsx (line 875)

When capturing a frame, the code creates a blob URL, triggers a download via link.click(), then immediately schedules revokeObjectURL with setTimeout(..., 0). The 0ms timeout fires on the next microtask, before the browser has started reading from the blob, resulting in a failed or empty download.

Test plan

• Capture a frame in the studio and verify the download completes successfully
• Verify the blob URL is eventually cleaned up (no memory leak)

🤖 Generated with Claude Code

[jrusso1020]

Real race — setTimeout(..., 0) queues the revoke as a macrotask that can fire before the browser kicks off the navigation triggered by link.click(), especially on slower devices. 1000ms is a safe upper bound for download initiation. LGTM.

[vanceingalls]

Additive review at 24a45cb0 — @jrusso1020 already verified and approved.

Audited

• packages/studio/src/App.tsx:875 (the setTimeout(..., 0) → setTimeout(..., 1000))
• CI: all required green ✓

Strength

James covered the race. setTimeout(..., 0) queues revokeObjectURL as a microtask that can fire before the synchronous-looking link.click() actually kicks off the browser's navigation/download machinery — especially on slow devices. 1000ms is a conservative upper bound.

Important — supersedes the ObjectURL portion of #795

#795 (Jefsky) ships the same fix (in useFrameCapture.ts rather than App.tsx — both are valid call sites of the same pattern), but bundles it with three unrelated changes and a broken LayersPanel.tsx new-file addition. Recommend landing this single-purpose PR and closing the ObjectURL portion of #795. I've flagged the same in #795's review.

Also note: this PR fixes the call site in App.tsx:875, but #795 fixes a SIMILAR pattern in packages/studio/src/hooks/useFrameCapture.ts:1. Worth a Rule 2 audit — grep "URL.revokeObjectURL" packages/studio/src/ and confirm both sites get the 1000ms treatment if the contract is "wait 1000ms before revoking a blob URL." Otherwise users hit the same race on frame capture but not on App.tsx, or vice versa.

Nit

• Worth a comment in the code explaining why 1000ms specifically — the next maintainer will see setTimeout(..., 1000) and wonder if it can be tightened. A one-line // Give the browser time to initiate the download before revoking. 0ms races with link.click(). would save a future archaeology session.

Verdict

Verdict: COMMENT
Reasoning: Fix is correct (James verified). Audit sibling site useFrameCapture.ts per Rule 2 — #795 fixes that one, this PR fixes the App.tsx one; both call sites need the same treatment to fully close the contract. External-contributor PR — Vance check before merging.

— Vai