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buzz/.github/workflows
Matt Toohey b1f76ef4d2 ci: cache the Tauri apt .debs and fit a cold Windows Rust run in its cap (#8679)
## Summary

Fixes the two CI workflow defects that turned `main` red most often in
the 21–28 Oct 2026 audit:

- **Desktop Tauri:** the lane now caches its apt `.deb`s. It no longer
re-downloads 62 MB from a slow Ubuntu mirror on every run.
- **Windows Rust:** the lane drops a duplicate `cargo check` and gets a
60 min cap, so a cold run can save its cache.

It also updates #8613's `scripts/flake-check.test.mjs`, which breaks
once the Tauri package list moves into an env var. There are no product
code or test-behaviour changes.

This is one of seven PRs split out of the `flakey-tests` branch
(siblings below).

### Related issue

None found. #8613 touched both workflows after the audit, but not these
steps. No open PR changes how the Tauri packages are fetched, the
Windows timeout, or its Check (workspace) step:

- #8422, #8321 and #8373 only add packages to the list, and would now
add them to `TAURI_APT_PACKAGES`.
- #8414 adds two mesh-llm Tauri steps to the Windows job. If it lands,
they must fit the cold budget below.

### CI failures fixed

| Lane / test | Failing runs | Cause | Change |
|---|---|---|---|
| Desktop Tauri, "Install Tauri dependencies (Linux)"
(`_ci-desktop.yml`) | 62 jobs in 51 run attempts, 22–27 Oct. On main:
39821769576, 39822883395, 39827234118, 40333705511, 40342468627,
40348069929, 40353619362, 40368315739, 40373404267, 40374519539,
40556742929 | All 3 `ci-apt-retry.sh` attempts hit their 420 s limit
while `azure.archive.ubuntu.com` served the 62 MB at 20–65 KB/s. The
25.5 MB `libwebkit2gtk-4.1-0` alone takes a whole attempt, and each
attempt loses its partial download. | The package list moves to a
job-level `TAURI_APT_PACKAGES`. A new "Resolve Tauri apt archives" step
builds the cache key from `apt-get install --print-uris -o
Acquire::ForceHash=SHA256` (name, size and SHA256 per file).
`actions/cache/restore` uses that key. The install step copies only the
restored files whose SHA256 matches the signed index, because apt 2.8.3
reuses any same-size cached `.deb` without hashing it. A best-effort
rebuild keeps exactly the listed files. `actions/cache/save` runs only
on core-lane pushes after a successful rebuild; PR runs never save. |
| Windows Rust (`_ci-rust.yml`) | All on main: 39796569342 (job
119885795086), 39821769576 (119975358772), 39827234118 (119994286695),
39865872891 (120128351939), 40402556064 (121852634685) | Every test
passed. Cold steps take 41.3–43.5 min, so the 45 min cap cancelled the
`Swatinem/rust-cache` post-run save 1.6–3.7 min in. No cache was
written, and the next push was cold again. | Delete "Check (workspace)".
The clippy step before it covers the same `--workspace --all-targets`
set with `-D warnings`, which saves 2.0–2.8 min. Raise `timeout-minutes`
from 45 to 60, with the measured breakdown in a comment: 39–41 min of
steps, a ~4.5 min save and ~15 min of margin. |
| `scripts/flake-check.test.mjs` "repeat invocations mirror the lanes
they stand in for" | None in CI yet: it fails only with this change
applied | #8613 added this test after `flakey-tests` branched. It checks
that the advisory `flake-tauri` lane installs the same packages as the
Desktop Tauri core lane, by regex-matching the inline `apt-get install
-y --no-install-recommends \` list in `_ci-desktop.yml`. That list now
lives in `TAURI_APT_PACKAGES`, so the regex matched nothing and the test
failed with "Desktop Tauri apt packages". | Read `TAURI_APT_PACKAGES`
from `_ci-desktop.yml` and compare package names (12 on each side) with
`_ci-flake.yml`'s list. Renaming one package in `_ci-flake.yml` still
fails the test. Giving the `flake-tauri` lane the same read-only `.deb`
restore is a follow-up. |

Local evidence is from the original `flakey-tests` commit (9aa768a3b):

- The apt steps ran verbatim in Ubuntu 24.04 containers with apt 2.8.3,
with the cache restore and the save step's `if:` emulated.
- On a miss, the install fetches everything ("Need to get 254 MB"). On
an exact hit with the network down, it fetches nothing ("Need to get 0
B/254 MB").
- On a fallback with one `.deb` missing and one corrupted at the same
size, the hash check rejects the corrupt file, and apt re-fetches only
the corrupt and missing files.
- The key was identical in all four simulated jobs.
- The Windows numbers come from the jobs API for the five runs above.

On this branch, the split session ran the `scripts/` node tests:
`ci-selection`, `ci-required-gates`, `ci-apt-retry` and `flake-check` on
macOS gave 84 pass, 0 fail and 8 skipped (Linux-only). Before the
`flake-check.test.mjs` fix, that test failed 1 case. The same session
ran actionlint 1.7.12 with shellcheck, which was clean, and the
rust-cache contract scripts, which passed.

### Verification

This branch was pushed without further local re-verification, by the
user's choice: local test runs were overloading the machine and failing
for that reason. **Hosted CI is the check.** It was pushed with `git
push --no-verify` over SSH. The pre-push hook runs tests, and the HTTPS
token lacks the `workflow` scope.

Only hosted CI can show:

- The runner's real package list (about 62 MB) and the same key in all
three Tauri lanes.
- The `actions/cache` round trip. The first PR run misses, because
`main` has no key yet. After merge, the first push to `main` saves it.
- A cold Windows run saving its cache within the new cap. The next
toolchain bump or cache eviction will show it.

Remaining risk: after Ubuntu updates a large package, runs fetch it from
the mirror until a push to `main` saves a new key.

### Readiness

CI-only change. AGENTS.md's readiness steps (agent review, then human
confirmation) are still outstanding, so `buzz-review-completed` is not
set.

### Merge order

Independent of the other six. It merges cleanly onto `main`, and with
every sibling, in any order.

### Sibling PRs

Split from `flakey-tests` (one PR per area): #8676 (PostgreSQL lease +
lane), #8677 (relay E2E helper + Windows shell), #8678 (mobile), #8680
(desktop product races), #8681 (desktop E2E state gates), #8682 (desktop
E2E composer + row actions).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Signed-off-by: Matt Toohey <contact@matttoohey.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-30 10:00:00 +11:00
..