fix(desktop): stop the subframe navigation e2e racing a fixed timer

[puemos]

Problem

• Every desktop release has failed since #96677 landed. The x64 macOS leg fails, so no x64 build reaches the update feed and finalize-release skips.
• One test fails, three attempts in a row, on three different runners: main-process.spec.ts › blocks external protocol navigation from a renderer subframe (run 34298858904).
• The test arms a will-frame-navigate listener behind a fixed 5 s timer, then builds an iframe in the renderer, then clicks. The timer measures the setup, not the behavior.
• The x64 build runs under Rosetta on an Apple silicon runner. The trace from attempt 2 shows the iframe creation alone took 16 s, so the timer expired about 10 s before the click could happen.
• fix(desktop): gate the release tag on master Desktop Tests #96677 was the first time this test ran under Rosetta. Before it, the x64 leg ran only the smoke spec.

Changes

• The x64 release leg passes again. No user-facing change.
• The listener now records the matching event on globalThis in the main process instead of rejecting after 5 s. The test polls for the record after the click with expect.poll, bounded to 30 s. That bound starts after the setup, so it measures event delivery alone and cannot be beaten by slow setup.
• The listener keeps an explicit on/off pair rather than once. The app can emit unrelated subframe navigations during boot, so a match filter is required.
• The app code under test, setupExternalLinkHandlers in external-links.ts, is unchanged.

Note

The release run cannot be re-run to green. The failure is deterministic, so this fix must ship in a new tag.

How did you test this code?

• Packaged the Linux app and ran the full Electron suite under xvfb the way desktop-test.yml does. 15 of 15 pass, including the rewritten test.
• Not run: the x64 macOS leg under Rosetta. This sandbox is Linux. The next release run is the real check for that leg.
• The regression this guards: a slow environment failing the test before the navigation is ever attempted.

Automatic notifications

• Publish to changelog?

Docs update

None.

🤖 Agent context

Autonomy: Human-driven (agent-assisted)

• Claude Code in PostHog Desktop, directed to find why the release failed and fix the root cause.
• Skills invoked: /writing-tests, /writing-pr-descriptions.
• The investigation covered all three attempts of the failing run and the Playwright trace artifact. A timeout bump was rejected because it only moves the cliff. Limiting the x64 leg to the smoke spec was discussed and deferred to a separate decision.
• Duplicate search found no open PR for this fix.

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Created with PostHog Desktop

[trunk-io]

😎 Merged successfully - details.

[github-actions]

React Doctor found no issues in the changed files. 🎉

_{Reviewed by React Doctor for commit 1c8ecf1.}

[github-actions]

🤖 CI report

✅ Trunk lane — non-backend lane (fe:product:desktop)

This PR is assigned to the non-backend lane (fe:product:desktop). It does not run backend Python tests and may merge in parallel with PRs in other lanes.

[hosthog]

HostHog preview — posthog-desktop-web

The previews for this PR have been torn down and no longer serve.

[posthog]

🦔 PostHog Review reviewed this pull request

Nothing worth raising this time, so here's a calming picture instead:

[puemos]

/trunk merge

[stamphog]

Approved.

Test-only fix replacing a flaky fixed-timer wait with an event-record-and-poll pattern in an e2e spec; no production code touched, diff matches description, single owning-team author.

• 1 of the 1 changed files are governed by products/desktop/AGENT_APPROVALS.md.

Gate mechanics and policy version

Gate		Result
prerequisites	✓	all clear
deny-list	✓	no deny categories matched
size	✓	0L, 0F substantive, 70L/1F incl. docs/generated/snapshots — within ceiling
tier	✓	T0 auto-approve: T0-deterministic (70L, 1F, single-area, fix)
stamphog 2.0.0b4		.stamphog/policy.yml @ 1c8ecf1 · reviewed head 1c8ecf1

[deployment-status-posthog]

Deploy status

Environment	Status	Deployed At	Workflow
dev	✅ Deployed	2026-09-09 07:57 UTC	Run
prod-us	✅ Deployed	2026-09-09 08:16 UTC	Run
prod-eu	✅ Deployed	2026-09-09 08:18 UTC	Run