[teamleaderleo]

Leo (2026-10-31): "IF YOU DONT MERGE STUFF LIKE THAT WITHIN THE DAY THERE'D BETTER BE AN EXTREMELY GOOD REASON ... WITHIN 3 HOURS IF NEEDS CHANGES / WITHIN THE HOUR IF STRAIGHTFORWARD".

Why

Today's webview PRs spent most of their ask-to-merge time waiting on web / react-apps-check (N). The webview verdict gate (react-apps-base-check) can't run until every head shard finishes. On 16 vCPU (#29033), each shard's "Test webviews" step runs its ~100 Vite dev-server files 4 at a time. That took 18-26 min per shard. For #29614 (removing the PR chip row), it was 29 of the 51 minutes from Leo's ask to the merge.

What

• react-apps-check-shard runs as 8 shards instead of 4, still on Blacksmith 16 vCPU, with the same 32 vCPU overflow.
• react-apps-base-check uses the same 8 shards, one per head shard's results artifact.
• Nothing else changes:
  • merge-guard reads the declared base-check matrix from this file.
  • webviews-test-durations and the react-apps-check verdict glob or aggregate whatever shards exist.
  • The LPT split in webviews_test_shards.py takes any count.
• The gate itself is unchanged: the same per-test verdict, now split across 8 shards.

Performance

metric	before	after	delta	harness or run link
slowest react-apps-check shard	p50 24.4 min (11 PR heads since #29033, max 33.1)	15.6 min (8 shards, 5.5 to 15.6)	-8.8 min	GraphQL check-run timings; after: run 41240581813
web-subarea-scope start to last react-apps-base-check	about 27 min (#29614: 19:54:50 to 20:21:54)	18.4 min (20:53:39 to 21:12:01)	about -8.6 min	runs 41236343549 / 41240581813
web-subarea-scope start to web / react-apps-check verdict	p50 26.4 min	22.4 min (includes a 4 min queue for the 4 vCPU aggregator job, 1 s on #29614)	-4 min measured, about -8 min without that queue	same
Blacksmith 16 vCPU head-shard minutes per webview run	about 4 x 23 = 92	92.5 (8 shards summed)	about 0	run 41240581813

The head shards cost about the same in total, because dev-server files dominate and the per-shard setup is small. The base replay adds 4 short jobs (about 1.5 to 2 min each).

Warm sources: unchanged. Each shard restores the bun and Playwright caches, and the shard split reads the shared durations manifest.

Changelog

none

Observed / Not run

• Ran: actionlint on ci-web.yml (clean).
• Ran: checked that every consumer of the shard set globs or reads the matrix (merge-guard webview_expected_shards, the durations merge, the verdict aggregator).
• Not run locally: the CI Python tests (heavy work isn't allowed on this host). This PR's CI runs them.

risk: CI-only (workflow matrix).

Agent session: agent session

🤖 Generated with Claude Code

[teamleaderleo]

Owned by an agent session · session

[github-actions]

cmux status _{(one comment, edited in place; each line is updated by the job that owns it)}

Review 2a6d342: HQ feed card · gallery before/after runs · checks

App of this head (app.zip, kept 1 day)

gh workflow run reload-build.yml -R manaflow-ai/cmux --ref feat-cmux-next -f tag=pr29666 -f ref=ci/webview-shards-8 -f platform=macos -f backend_mode=local

Shipped in:

• cmux NEXT nightly 1.0.0-nightly.4124615690001 (e7a61acd4a)
• cmux NEXT nightly 1.0.0-nightly.4124926880101 (1d08cfcafe)
• cmux NEXT nightly 1.0.0-nightly.4125030115701 (b2ec1ee1b6)

[teamleaderleo]

Review (codex gpt-6-astra high, router-review): BLOCK at 99498da

BLOCK at 99498da

Visual verdict: no images; Leo tries the build

1. [P1][blocking] The workflow now declares eight shards at .github/workflows/ci-web.yml:320, but tests/test_web_validation.py:233 still asserts there are exactly four. Running python3 tests/test_web_validation.py fails with AssertionError: 8 != 4; cmux-next-guards runs this test on every PR, so the required guard is red until the test is updated.

[teamleaderleo]

Review (codex, router-review): SHIP at 2a6d342

Reviewer: codex gpt-6-astra high, fast tier.

SHIP at 2a6d342

Visual verdict: no images; Leo tries the build

No correctness findings. Head/base matrices match, and artifact aggregation supports eight shards. All 53 focused Python tests passed. CI performance remains unverified locally.

Follow-ups: none