ci probe: tier1-spike2 isolation (do not merge)

[ryansolid]

Attribution probe for #2923's CodSpeed result (merge-mixed −28%, alongside merge-static ×2.2 / reconcile +92% / update1to1 +5.5% improvements). Isolates one spike. Closes after CodSpeed reports.

[changeset-bot]

⚠️ No Changeset found

Latest commit: d97746c

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[github-actions]

size-limit report 📦

Path	Size
signals: core floor (createSignal/Memo/Effect/Root/flush)	6.53 KB (-1.44% 🔽)
signals: + createStore	11.14 KB (-0.62% 🔽)
signals: + isPending/latest	8.2 KB (+0.26% 🔺)
app: render + one signal (the simple-app floor)	9.07 KB (-1.38% 🔽)
app: CSR with Show/For/Loading/Errored/lazy	11.13 KB (-0.68% 🔽)

[coveralls]

Coverage Report for CI Build 29784307146

Warning

No base build found for commit 2bf022e on next.
Coverage changes can't be calculated without a base build.
If a base build is processing, this comment will update automatically when it completes.

Coverage: 75.328%

Details

• Patch coverage: No coverable lines changed in this PR.

Uncovered Changes

No uncovered changes found.

Coverage Regressions

Requires a base build to compare against. How to fix this →

---

Coverage Stats

Relevant Lines:	778
Covered Lines:	626
Line Coverage:	80.46%
Relevant Branches:	592
Covered Branches:	406
Branch Coverage:	68.58%
Branches in Coverage %:	Yes
Coverage Strength:	14.11 hits per line

---

💛 - Coveralls

[codspeed-hq]

Merging this PR will regress 1 benchmark

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 2 improved benchmarks
❌ 1 regressed benchmark
✅ 118 untouched benchmarks

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
❌	merge	266.5 µs	369.6 µs	-27.9%
⚡	merge	165.2 µs	73.3 µs	×2.3
⚡	reconcile: deep tree, 10 of ~12k paths subscribed	6.4 ms	3.3 ms	+92.01%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing probe/tier1-spike2 (d97746c) with next (2bf022e)}

[ryansolid]

Probe result: reproduces #2923's merge deltas exactly in isolation — merge-mixed −27.9% AND merge-static ×2.3, the coupled pair. Confirms both come solely from the affects-channel read()-shape change. Since merge-mixed is a plain-JS getter/value descriptor bench (getter body return 1, no Solid primitive) that never calls read(), the −28% is shared-VM JIT redistribution, not a per-op cost. Findings folded into #2923.