ci: make the aggregate app-host product the default, layers opt-in

[teamleaderleo]

What

ci-macos.yml's product_artifacts input now defaults to aggregate. Compile admission stops packaging and uploading the four app-host layer artifacts and their index. App-host shards and tests-build-and-lag then skip "Restore selective app-host product layers" and read the aggregate product: node-local cache, trusted peer, R2 when configured, then parallel range requests. product_artifacts: layered still turns the layers on for a canary, as docs/ci/app-host-layer-transport.md describes.

Why

Layers are slower on both ends. Measured on five full-suite PR runs on the owned minis (runs 36287456496, 36288708517, 36311480979, 36271916361, 36274774841):

	layered	aggregate
compile admission, after the aggregate upload	+100 to 255 s (package, 4 uploads, index upload)	0
shard product fetch	68 to 231 s, median ~115 s (n=17)	34 to 90 s, median ~70 s (n=18, parallel transport)

Every shard needs compile admission, so the layer uploads sit on the critical path of every full-suite run. Each shard also holds its mini's gui token for the whole job. Over the last 24 h, gui-pool shards queued 362 minutes. During those waits the fleet held a median of 10 gui tokens with fewer than half its capacity units in use, so the gui token was the binding constraint. With this change each full-suite run should finish about 2 to 4 minutes sooner, and each shard should hold the gui token about 45 s less.

Layers became the default in #13567, a large squash whose stated purpose was peer transport. The parallel aggregate transport (74b94e3) landed after it.

Tests

python3 tests/test_ci_selective_layer_wiring.py passes. The default assertion is updated, and the other wiring checks are unchanged.

🤖 Generated with Claude Code

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Summary by cubic

Makes the aggregate app-host product the default in ci-macos.yml, with the layered transport now opt-in via product_artifacts: layered, as docs/ci/app-host-layer-transport.md describes.

• Measured on owned minis: layers added 100–255 s to compile admission and 68–231 s to shard restores, versus 34–90 s for the aggregate over parallel range requests.
• Shards now skip "Restore selective app-host product layers" and read the aggregate product from node-local cache, trusted peer, R2, then parallel range requests; a canary can re-enable layers by passing product_artifacts: layered from ci.yml's macos call.
• Updates the default assertion in tests/test_ci_selective_layer_wiring.py; other wiring checks are unchanged.

^{Written for commit 6829244. Summary will update on new commits.}

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📥 Commits

Reviewing files that changed from the base of the PR and between 52dce98 and 6829244.

📒 Files selected for processing (2)

• .github/workflows/ci-macos.yml
• tests/test_ci_selective_layer_wiring.py

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[github-actions]

Merge receipt for 68292448b3, merged 2026-09-27 11:46:19 UTC

• Not verified at merge: ci-status (not reported), macOS compile admission (in progress), CI fast guards (in progress), guards (15) (in progress)
• Verified: Web complexity, web-validation, Fast static checks, receipt-contract, Testbox broker trust boundary, transport
• Skipped by policy: admission-placement, browser, Claude wrapper regressions, GhosttyKit release check, remote-daemon, suite-coverage, swift-package-tests, web, web-build, web-database-tests, web-tests
• Full suite: runs on main after merge.

Labeled merged-unverified: if main breaks near this merge, look here first.