finding(test-config): the `unit` project's `isolate: false` is justified by a comment that is false — registry-writing AND registry-absence tests both live there

[os-warren]

Found while widening the import set in #7117 (PR #7133). Filed, not fixed — nothing is red today, and which way to close it is a test-config decision outside that card.

The claim

vitest.config.mts turns off per-file isolation for the unit project, and states the premise that makes it safe:

The unit project is node-env pure logic with no ComponentRegistry or DOM state to leak across files, so it can share a module graph per worker instead of re-executing it per file. Measured 3.2x faster (38s -> 12s for the project) with zero failures, holding green across repeated and shuffled runs.

ComponentRegistry is a module-level singleton, so under a shared module graph one file's side-effect registrations are visible to every later file in the same worker.

The premise is false in both directions

Both halves of the hazard the comment says does not exist are present in the unit project today (*.test.ts, not in domTsTests, therefore node env with isolate: false):

• A writer. packages/app-shell/src/views/metadata-admin/previews/__tests__/exclusion-reason-truthfulness.test.ts performs side-effect registrations into the shared singleton — three package imports before finding(app-shell): exclusion-reason-truthfulness's import set excludes app-shell, so a false "no renderer" on a shell singleton passes green #7117, ten package/leaf imports after it (@object-ui/components, plugin-chatbot, plugin-form, plugin-detail, and this package's six views/*-renderer.tsx leaves).
• A reader that asserts ABSENCE. packages/fields/src/__tests__/capability-multiselect-retired.test.ts:81-82 asserts ComponentRegistry.get(...) is toBeUndefined() for a retired key. A negative registry assertion is exactly the shape a shared registry can flip, and it is the one shape that cannot fail safe: if some other file registers that key first, this one goes green while proving nothing.

So the config's stated reason for the optimisation does not hold, and the reason is the only thing a future author consults when deciding whether a registry-touching suite may live in this project.

Latent, not live — measured

pnpm exec vitest run --project unit on PR #7133's branch, with the widened import set: Test Files 801 passed (801) / Tests 12489 passed | 9 skipped (12498), exit 0. No key registered by any writer collides with any key asserted absent, so nothing is wrong today. The cost is future-tense: the next field:* or element:* registration added to a unit-project file can silently satisfy an absence assertion somewhere else in the same worker, and the failure mode is a green.

This is the same shape as #7117 one level down: there, a guard could not see what it certified; here, a config comment certifies a property the tree no longer has.

Directions (not prescribed)

• Correct the comment to state the real invariant — something like "registry writes and registry-absence assertions must not collide" — so the constraint is at least written down where it is relied on.
• Or make it mechanical: a gate that fails when a key asserted absent in one unit file is registered by another, which is the only version that survives the next author.
• Or move registry-touching *.test.ts files out of the shared-graph project, which costs the 3.2x on those files only.

Refs: #7117 · PR #7133 · #2648 (the change that introduced isolate: false for the DOM projects).

[yinlianghui]

Claim: PM loop round R40 (backfill after #7183 returned; batch=5)
Session: session_01BGMDbrVa8JjZcCQ7DWYH1b
Branch: claude/issue-7134-unit-isolate-premise
Worktree: objectui-issue-7134
Domain: domain:devx
File surface: vitest.config.mts (the unit project's isolate: false comment at lines 184–208 — comment text and, only if the guard needs it, the project's exclude list) and one new guard under scripts/__tests__/ (plus its helper if any); the registry-absence test files the guard names may gain the isolation-proof pattern (rule 3) but ⛔ no assertion is weakened, removed or skipped. ⛔ No change to the dom / dom-heavy / dist projects, ⛔ no timeout raised, ⛔ no heavyDomTests entry. Stop on breach; explain in the report.
Container & model: M (one guard with ablation plus a config-comment correction), mode:subagent, model: opus. Tier is this seat's explicit decision (no dispatch-gates.mjs in objectui).
Clause-②: no
Serial constraints cleared: vitest.config.mts on origin/main eb33a8d4c was last moved by 8ec11e14f (#7180); PR #7291 (#7183, ACCEPTed, flip pending) appends a dist project and two constants to the same file in a different region — the dev merges origin/main after #7291 lands before opening the PR, and reports a conflict rather than resolving one by hand if the hunks touch. Batch siblings (#6640 test infra · #5174 docs ledger · #6214 README gate · #6578 e2e) are disjoint. Seat reading on origin/main: 7 *.test.ts files under packages/*/src carry a ComponentRegistry.get(...) absence-style assertion (population for the guard, to be re-derived); the writer the card names imports four package barrels and six app-shell renderer leaves for their side effects (lines 98–115).
Label note: finding stays on the card — the execution seat does not produce finding transitions; triage sheds it.

Ruling (seat discretion — verification strategy): the comment correction is mandatory and the cheap half; it ships together with ONE mechanical guard proven by ablation, because a comment "is the only thing a future author consults" and the card's own point is that it already went false once. The guard's shape is the dev's to choose (suggested route in the dispatch order); moving registry-touching files out of the shared-graph project is the fallback only if no guard can be made non-vacuous, and then the cost is reported per file.

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[yinlianghui]

Claim (os-dev): starting work on this card.

Session: session_01BGMDbrVa8JjZcCQ7DWYH1b
Branch: claude/issue-7134-unit-isolate-premise (pushed, empty, write access verified)
Worktree: objectui-issue-7134 off origin/main eb33a8d4c
File surface: vitest.config.mts (the unit project's isolate: false justification comment only — isolate itself is not touched, and no change to dom / dom-heavy / the dist project PR #7291 adds), one new guard under scripts/__tests__/ plus its helper if needed, and — only if the chosen guard shape requires it — the isolation-proof pattern on registry-absence test files (no assertion weakened, removed or skipped).

Plan: re-derive both populations (writers into the ComponentRegistry singleton; readers asserting a key ABSENT) inside the unit project on today's tree, confirm the collision is latent rather than live, then ship the corrected comment together with ONE mechanical guard proven by ablation (planted collision RED, restore proven by blob hash, plus a non-vacuity control).

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