fix(desktop): allow clipboard writes in the preview browser

[carlosricojr]

Problem

Built-in copy-to-clipboard buttons inside the preview browser don't work. The clearest example is the Next.js / Vercel error overlay's copy button, which surfaces:

execute 'writeText' ... 'Clipboard': Write permission ...

i.e. the DOMException Failed to execute 'writeText' on 'Clipboard': Write permission denied. Any preview page calling navigator.clipboard.writeText() (or .write()) hits the same wall.

Root cause

apps/desktop/src/preview/BrowserSession.ts configured only a setPermissionRequestHandler, and its allow-list granted "clipboard-write":

const allowed = ["clipboard-read", "clipboard-write", "notifications", "geolocation"];
callback(allowed.includes(permission));

Two bugs:

1. clipboard-write is not a valid Electron permission name. The async Clipboard write API maps to clipboard-sanitized-write (Electron session docs), so the intended grant never matched.
2. The write is gated by the permission check handler, which was never set. Per the docs: "you must also implement setPermissionRequestHandler to get complete permission handling. Most web APIs do a permission check and then make a permission request if the check is denied." Async clipboard.writeText() performs a synchronous clipboard-sanitized-write check; with no setPermissionCheckHandler, Electron's default denies it — hence "Write permission denied".

Fix

• Add a setPermissionCheckHandler alongside the existing request handler.
• Use the correct permission name clipboard-sanitized-write.
• Share a single ALLOWED_PREVIEW_PERMISSIONS set between both handlers so they can't drift.

The granted set is unchanged in intent (clipboard-read, clipboard write, notifications, geolocation) — this only corrects the write permission and wires up the check path. No new capabilities are exposed.

Test

Extends BrowserSession.test.ts (adds setPermissionCheckHandler to the electron mock) with a case asserting both handlers grant clipboard-sanitized-write (plus the other allowed permissions) and deny the stale clipboard-write name and unrelated permissions like midi.

Verification

• tsgo --noEmit (apps/desktop): 0 errors
• vitest run src/preview/BrowserSession.test.ts: 6/6 passed
• vp lint on the changed files: clean

🤖 Generated with Claude Code

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Note

Low Risk
Small, localized preview-session permission fix with no new capabilities beyond correcting clipboard write; covered by new unit tests.

Overview
Fixes copy-to-clipboard in the desktop preview (e.g. Next.js/Vercel error overlay) by correcting Electron permission handling in BrowserSession.

Preview sessions now register setPermissionCheckHandler in addition to the request handler, because async navigator.clipboard.writeText() is gated on a synchronous permission check. Both handlers share a new ALLOWED_PREVIEW_PERMISSIONS set that swaps the invalid clipboard-write name for clipboard-sanitized-write, while keeping the same intended grants (clipboard-read, notifications, geolocation).

Tests extend the Electron mock and assert both handlers allow the real clipboard write permission and deny stale or unrelated names like midi.

^{Reviewed by Cursor Bugbot for commit 4520cdb. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Fix clipboard writes in the preview browser by registering both permission handlers

• Adds ALLOWED_PREVIEW_PERMISSIONS constant in BrowserSession.ts containing clipboard-read, clipboard-sanitized-write, notifications, and geolocation.
• Replaces the stale clipboard-write permission with clipboard-sanitized-write, which is the correct Electron permission for sanitized clipboard access.
• Adds a setPermissionCheckHandler alongside the existing setPermissionRequestHandler so permissions are enforced through both the synchronous check and async request paths.

^{Macroscope summarized 4520cdb.}

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[macroscopeapp]

Approvability

Verdict: Approved

Straightforward bug fix that corrects Electron permission API usage to enable clipboard writes in the preview browser. The change uses the correct permission name (clipboard-sanitized-write) and adds the required check handler. No new permissions are introduced; comprehensive tests cover the behavior.

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