Fix navigator.clipboard.writeText in @electron/remote MenuItem handlers

[bengotow]

Sentry Issue

MAILSPRING-CLIENT-2R — 16 users affected, 30 events, ongoing since May 2026

Root Cause

When a user right-clicks on a contact name/email in the message header, a context menu appears with a "Copy email address" item. Clicking it called navigator.clipboard.writeText(contact.email), which reported Error: Unknown error to Sentry.

The context menu's click handler is invoked via @electron/remote IPC — the main process calls back into the renderer via IPC after the menu item is selected. At that point:

1. The rendering window no longer has focus (it lost focus when the OS-native context menu appeared)
2. navigator.clipboard.writeText() is a Web Clipboard API that requires both a transient user gesture and an active, focused browsing context
3. When called through an IPC callback, neither condition is guaranteed, causing the browser to reject the write with "Unknown error"

Fix

Replace navigator.clipboard.writeText() with @electron/remote's clipboard.writeText(), which routes through Electron's main-process clipboard API and works regardless of window focus. As a bonus, the call is now synchronous so there's no unhandled promise rejection.

This pattern was present in five files — all fixed in this PR:

• app/internal_packages/message-list/lib/message-participants.tsx — Copy contact email (original Sentry report)
• app/internal_packages/main-calendar/lib/core/event-attendees-input.tsx — Copy event attendee email
• app/src/components/participants-text-field.tsx — Copy participant email
• app/src/components/evented-iframe.tsx — Copy Email Address / Copy Link Address / Copy selected text
• app/internal_packages/thread-list/lib/thread-list-context-menu.ts — Copy mailbox permalink

🤖 Generated with Claude Code

https://claude.ai/code/session_01GqXVeX65b7daqB5rU4jTuJ

[indent-staging]

PR Summary

Fixes Sentry issue MAILSPRING-CLIENT-2R where @electron/remote MenuItem click handlers calling navigator.clipboard.writeText failed with "Unknown error" because the Web Clipboard API requires window focus + user gesture in the current browsing context, which is lost when the click is dispatched through @electron/remote IPC. The fix routes clipboard writes through @electron/remote's clipboard module instead (Electron's main-process clipboard, synchronous, no focus/gesture preconditions). Other navigator.clipboard.writeText call sites that are driven by renderer-side DOM/button clicks or keymap commands are intentionally left alone since they aren't affected.

• app/internal_packages/message-list/lib/message-participants.tsx: destructure clipboard from @electron/remote and call clipboard.writeText(contact.email) in the participant context menu.
• app/internal_packages/main-calendar/lib/core/event-attendees-input.tsx: same migration for the "Copy " attendee menu item.
• app/src/components/participants-text-field.tsx: same migration for the "Copy " participant menu item.
• app/src/components/evented-iframe.tsx: same migration for the three iframe menu items (Copy Email Address, Copy Link Address, Copy text).
• app/internal_packages/thread-list/lib/thread-list-context-menu.ts: same migration for the "Copy mailbox permalink" thread context menu item.
• app/internal_packages/message-list/lib/message-controls.tsx: same migration for the "Copy Debug Info to Clipboard" action in the message actions menu.

Issues

All clear! No issues remaining. 🎉

2 issues already resolved

• message-controls.tsx has the same @electron/remote MenuItem → navigator.clipboard.writeText pattern but was not migrated, so "Copy Debug Info to Clipboard" in the message actions menu will still hit MAILSPRING-CLIENT-2R. _onShowActionsMenu wires { click: this._onCopyToClipboard } (lines 117-133), and _onCopyToClipboard calls navigator.clipboard.writeText(data) (line 183) — swap to the clipboard from @electron/remote like the other files in this commit. (fixed by commit 3a101d3)
• Same navigator.clipboard.writeText pattern inside @electron/remote MenuItem click handlers still exists in event-attendees-input.tsx, participants-text-field.tsx, evented-iframe.tsx (Copy Email/Link Address), and thread-list/lib/thread-list-context-menu.ts — they are likely susceptible to the same MAILSPRING-CLIENT-2R failure mode and could be migrated to clipboard.writeText in a follow-up. (fixed by commit b9d5085)

CI Checks

All CI checks passed on 3a101d3.

Custom Rules 3 rules evaluated, 3 passed, 0 failed

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