id(ci): nightly NixOS VM checks fail — home page no longer contains 'Files' (serve/e2e assertions, integration timeout) #896

Finding (issue-sweep-devtoday-code, 2026-10-25 run)

The id e2e nightly workflow has failed five consecutive nights (runs 39604059698, 39783189972, 39955079614, 40092359401, 40193900320). The latest run is now root-caused — it is NOT the historical #257 disk failure and NOT the #229 Firefox cluster:

Run 40193900320 (2026-10-25, head 2d6d1c1) — sole job nix flake check (full)

All non-VM checks pass, and the Playwright test-e2e check passes 113/113. Exactly the NixOS VM checks fail:

• nixos-serve — AssertionError: [port 3000] Home page missing 'Files' (pkgs/id/nix/tests/serve-test.nix:64). The served home page HTML begins <!DOCTYPE html><html lang="en" data-theme="sneak">…<title>Home - id</title> — no Files in the initial HTML.
• nixos-e2e — AssertionError: [port 4173] Home page DOM missing 'Files' (pkgs/id/nix/tests/e2e-test.nix:81), same cause.
• nixos-integration — VM test driver hit timeout reached; test terminating… and the builder died with exit code 143 (vm-test-run-id-integration.drv); the server VM booted cleanly (DHCP lease, multi-user target reached), so this looks like the same home-page/content expectation never being satisfied rather than a boot failure.
• nixos-playwright-e2e was still running when the run was summarised; the three failures above already fail the job.

Why it matters

The nightly is the only place the NixOS VM checks run, so it has been red for a week and real regressions in the VM-tested paths are invisible. Either the home page changed (the Files section is now client-rendered or moved — cf. pkgs/id/src/web/templates.rs:154, routes.rs:355, where a Files card/page still exists on other routes) and the VM tests' expectations are stale, or the home page regressed and stopped server-rendering content it used to include.

Acceptance criteria

• Determine which side is wrong: if the home page intentionally no longer server-renders Files, update serve-test.nix / e2e-test.nix (and the integration test's waits) to assert on content the home page actually guarantees (e.g. title / shell markers / a hydrated DOM check like the Playwright suite uses).
• If the home page regressed, restore the server-rendered Files content on /.
• nixos-integration no longer times out: it passes, or its failure mode becomes a fast, legible assertion.
• One full nightly run (or a local/laptop nix flake check including the four nixos-* checks) is green.