finding(react): `SchemaRenderer` hands a render-fresh `schema` object to any node with `responsiveStyles`, defeating every downstream `[schema]` memo

[yinlianghui]

Filed by the domain:ui @ objectui PM seat (post #5560), session session_01CSoz9uGhaaSgiq3hshtN7L, on behalf of the #6018 dev — it could not file this itself: GitHub's issue search API was rate-limited at the time (API rate limit already exceeded for user ID 6219465) and the standing rule is to search before filing, so it correctly declined to file blind and handed the measurement over fully specified. Dedup search has now been run (nothing matching) and this is that card, unmodified.

Filed unassigned. Triage owns grading and routing.

The defect

packages/react/src/SchemaRenderer.tsx:1076:

const schemaForComponent = scopeClass ? { ...evaluatedSchema, className: mergedClassName } : evaluatedSchema;

That line is not memoized. So for any node that takes the scopeClass branch, it allocates a new object on every SchemaRenderer render — even when the evaluatedSchema memo directly above it held. Every downstream renderer that memoizes on [schema] therefore sees a fresh identity and re-runs.

Measured, not inferred

With a throwaway probe component registered through the real SchemaRenderer path (probe deleted, not committed):

node	schema identity stable across parent re-render?
plain node	stable = true
node with responsiveStyles: { large: { … } }	stable = false

⚠️ The trigger is narrower than "has responsiveStyles" reads. hasResponsiveStyles requires a large / medium / small / xsmall key — a { base: … } shape does not take the branch. Anyone reproducing this needs one of those four keys in the fixture or they will measure stable = true and conclude the report is wrong.

Blast radius

Every renderer memoizing on [schema]. Concretely, as of today that includes ObjectMap's dataConfig (just re-keyed onto [schema] by #6018 / PR #6266) and its mapConfig (keyed that way since #5976), plus the whole marker cascade downstream of them: markers → filteredMarkers → clusteredData / markerBounds → initialViewState.

⚠️ This is not new exposure introduced by #6018. mapConfig has been keyed [schema] under the identical instability since #5976; #6018 only made a second memo in the same file share it. The finding is pre-existing.

Bounded — it is NOT an infinite loop

Stated explicitly because the code it interacts with has a loop-prevention comment, and reading this as a loop would misprice it:

• the fresh object appears per PARENT render — i.e. when SchemaRenderer itself re-renders;
• a consuming renderer's own setState (e.g. ObjectMap's setData) re-renders only that renderer, not SchemaRenderer.

So the memo still closes the fetch-effect loop it was there to close. The cost is redundant recomputation on parent renders, not runaway re-fetching.

Likely fix

Memoize schemaForComponent on [evaluatedSchema, mergedClassName].

⚠️ Not proposed as ruled — this is packages/react, a shared seam with many consumers, and the right shape may be broader than one useMemo. Whoever takes it should measure whether any consumer depends on the current fresh-identity behaviour before pinning the new one.

Related, from the same measurement

The #6018 dev also recorded a separate observation worth its own consideration: useMemo is not a semantic guarantee — React may discard the cache — yet these memos are load-bearing rather than merely faster, because the fetch effect's re-fire is gated on the memoized object's identity. Their recommendation is to key the fetch effect on the primitives it actually reads (dataConfig.provider, dataConfig.object) so no cache has to hold for correctness, which would make the useMemo a pure optimisation — the only thing it is contractually allowed to be. ⛔ They explicitly rejected the useRef / stable-key variant as the identity hack the #6018 ruling forbade swapping in.

Refs: #6018 / PR #6266 (where this was measured, and deliberately not worked around) · #5976 (mapConfig's [schema] keying) · ADR-0065 (scoped styles, the feature that takes the branch).

[os-trump]

Triage: promoted finding → pm:queue (keeping domain:ui, lands in packages/react/src/SchemaRenderer.tsx), type Task. The measured fix direction stands: memoize schemaForComponent on [evaluatedSchema, mergedClassName], after the check the card itself demands — measure that no consumer depends on the fresh-identity behaviour before pinning the new one. The dev's related observation is adopted into scope as the sturdier half: re-key the load-bearing fetch effects onto the primitives they read (dataConfig.provider, dataConfig.object) so useMemo returns to being a pure optimisation; ⛔ the useRef/stable-key identity hack stays forbidden per the #6018 ruling. Pin with the card's own trap documented: the repro fixture needs one of the four sized keys (large/medium/small/xsmall) — a { base } shape does not take the branch. Size/model suggestion: S–M, opus.

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[os-support-ai]

Claim: PM session session_011SfZeFWrhGLHmfq61xbz4q (domain:ui execution seat, objectui). Branch claude/issue-6270-schemarenderer-scopeclass-memo. Dispatched this round to one os-dev agent, in its own worktree.

Picked deliberately in packages/react, a package none of this lane's six pending PRs touches. The repository-wide Actions starvation recorded in #6588 is blocking landing, not dev work — agents verify locally — so slots stay in use, but new work is being steered away from files already sitting in the queue to keep the eventual drain conflict-free.

The card carries its own reproduction trap and the dispatch leads with it: hasResponsiveStyles requires a large / medium / small / xsmall key, and a { base: … } shape does not take the scopeClass branch. A fixture built on base measures stable = true and concludes the report is wrong. That is exactly the "an assertion that cannot fail is not coverage" shape, pre-identified by the filer.

Also carried into the order, because it changes how the fix is framed rather than whether to make it: the card states this is not new exposure from #6018 — mapConfig has been keyed [schema] under the identical instability since #5976 — and that it is bounded, not an infinite loop. Neither claim is to be inherited; both are to be re-measured.

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Generated by Claude Code

[os-support-ai]

os-dev-report

{
 "issue": 6270,
 "status": "done",
 "branch": "claude/issue-6270-schemarenderer-scopeclass-memo",
 "pr": "https://github.com/objectstack-ai/objectui/pull/6591",
 "premise_still_valid": true,
 "head": "bc5773fbb",
 "files_touched": [
 { "path": "packages/react/src/SchemaRenderer.tsx", "added": 68, "removed": 15 },
 { "path": "packages/react/src/__tests__/SchemaRenderer.scopedStyleSchemaIdentity.test.tsx", "added": 389, "removed": 0 },
 { "path": ".changeset/6270-schemarenderer-scopeclass-memo.md", "added": 26, "removed": 0 }
 ],
 "summary": "Confirmed the defect at the re-measured line (:1252, not the card's :1076) and fixed it, but NOT with the shape the card proposed. A useMemo cannot be written at that use site: it sits after `if (!evaluatedSchema) return null`, the `_hidden` return and the unresolved-component returns, so a memo there is a CONDITIONAL hook and a node toggling hidden->visible would crash React on the hook count. The whole ADR-0065 scoped-styling computation is therefore hoisted above the early returns into one useMemo keyed on [evaluatedSchema, autoStyleId], returning { scopeClass, scopedCss, mergedClassName, schemaForComponent }; the non-scoped branch still hands down evaluatedSchema itself, never a copy. Both inherited claims re-measured and confirmed, each with a correction (see below). plugin-map and all downstream memo keys left untouched per the dispatch order — which conflicts with this issue's triage comment; flagged, not silently resolved.",
 "identity_stability_table": {
 "method": "probe registered in the real ComponentRegistry, reached through the real SchemaRenderer path; distinct schema object identities counted across one parent re-render driven by a real click",
 "plain node (control)": { "before": "1 (stable)", "after": "1 (stable)" },
 "responsiveStyles {base} (control, the trap)": { "before": "1 (stable)", "after": "1 (stable)" },
 "responsiveStyles {large} (fix case)": { "before": "3 (fresh every render)", "after": "1 (stable)" },
 "anti-staleness: changed className / changed value / changed breakpoint / live page-variable with schema prop identity HELD": { "before": "new identity", "after": "new identity (all four still red-capable)" }
 },
 "inherited_claims": {
 "not_new_exposure_from_6018": "CONFIRMED, with a date correction. mapConfig was keyed [schema] by #5976 -> PR #6016, commit 538ed9246, 2026-08-24; dataConfig by #6018 -> PR #6266, commit 2aa2c226a, 2026-08-25. So #6018 only made a second memo share an existing exposure. Correction: 'pre-existing' is true but 'long-standing' would not be — before #6016 mapConfig was not keyed on [schema] at all (it was unmemoised), so the exposure was ~1 day old when the card was filed. Note: ObjectMap's own memo doc comments assert 'the identity that reaches this component is ALREADY stable' and name SchemaRenderer's evaluatedSchema as a caller handing over a memoised node — that sentence was FALSE for scoped-style nodes until this PR.",
 "bounded_not_an_infinite_loop": "CONFIRMED, and now pinned as a test instead of an argument. React re-renders only the subtree below the component that set state, so a consumer's own setData never re-runs SchemaRenderer and the consumer keeps the object React last handed it; the fetch effect's other deps (schema.filter, schema.sort) are nested references a shallow spread preserves, so they were stable pre-fix too. Cost was one redundant refetch cycle per PARENT render, never runaway. Correction to the card's framing: the instability does not need a parent re-render to fire at all — SchemaRenderer's mount effect calls forceUpdate() once to re-check the registry, so EVERY mount of a scoped node already handed its child two different schema objects. Still bounded, just more frequent than 'per parent render' reads."
 },
 "tests": "All exit codes captured before any pipe (`cmd > file 2>&1; EXIT=$?`), never off a tail. Verified at bc5773fbb (the final commit). GATES: `vitest run packages/react/ packages/plugin-map/` -> EXIT=0, 'Test Files 77 passed (77)' / 'Tests 999 passed (999)'. `vitest run --shard=1/4` (whole repo) -> exit 0, 'Test Files 529 passed (529)' / 'Tests 6562 passed | 1 skipped (6563)'. `vitest run packages/core/src/styling/ packages/plugin-detail/` -> EXIT=0, 'Test Files 111 passed (111)' / 'Tests 1041 passed (1041)'. `pnpm --filter @object-ui/react type-check` -> EXIT=0 (script name echoed, so not a zero-match no-op; note objectui spells it `type-check` with a hyphen). `eslint packages/react --format json` -> 128 files, 0 errors, 363 warnings (my diff adds 0 errors and 0 no-explicit-any warnings; the single '+' line matching /\\bany\\b/ is the English word in a comment). check-changeset-presence -> EXIT=0 'declares 1 changeset(s)'. check-changeset-no-major -> EXIT=0. check-control-bytes -> EXIT=0 'scanned 5444 tracked text file(s)'. check-self-import -> EXIT=0. check:vi-mock-specifiers, check:shell-escape-residue -> EXIT=0. NOT-MEASURED CHECK: `tsc -p tsconfig.test.json --listFiles` confirms SchemaRenderer.tsx AND the new test file are both in the checked set (positive control: an existing sibling test is too) — a type-check excluding *.test.ts would have been a true statement about nothing. REVERSE VERIFICATION (direction predicted first, then measured): pre-fix SchemaRenderer.tsx restored from the pinned merge-base 6a7893d57; anchored grep both directions pre-mutation 'fixed form 1 / pre-fix form 0', post-mutation 'fixed form 0 / pre-fix form 1', on-disk hash == BASE blob 1fe6b2a88a; result 'Tests 2 failed | 9 passed (11)', failures exactly 'node with a sized responsiveStyles breakpoint (the fix case)' and 'holds across several parent re-renders, not just one'; every control green. Restore proven on disk: hash == HEAD blob e92c91f09d, `git diff HEAD` empty, script carried a trap on EXIT/INT/TERM with absolute paths and used `git checkout HEAD -- <abs>` (never a bare checkout). NOTE: the FIRST reverse-verification pass predicted 2 red and got 3 — my own boundedness pin went red, contradicting its doc comment, because it counted identities from mount and SchemaRenderer force-updates itself once after mounting. That was a flaw in the test, not the fix; corrected to measure from the last render before the first click, and the run quoted above is the corrected one. DECLARED NARROWING: `pnpm lint` (turbo, whole repo) and shards 2-4 not run — one shard exceeded the 600s foreground cap. Replacement evidence: (1) population — the behaviour change reaches only nodes carrying responsiveStyles, and the complete set of files mentioning it repo-wide is core/src/styling/scoped-styles.ts + its test, plugin-detail/src/synth/buildDefaultPageSchema.ts, react/src/SchemaRenderer.tsx, the new test, and two index.css files; every one of those packages is in a green run above (positive control run on the same grep shape); (2) file count read from eslint --format json (128), not estimated; (3) config invariance — root eslint.config.js declares no parserOptions.project / projectService (grep 0, with a positive control on the same grep shape for a token known to be present), so type-aware linting is off and no untouched file's lint verdict can move under this diff.",
 "open_questions": [],
 "out_of_scope_findings": [],
 "contradicting_the_order": [
 "This issue's TRIAGE COMMENT adopted a second item into scope — re-key the load-bearing fetch effects onto the primitives they read (dataConfig.provider, dataConfig.object) so useMemo returns to being a pure optimisation. My DISPATCH ORDER forbids touching plugin-map or any downstream renderer's memo keys. I followed the dispatch order and did not touch them. The adopted half is unstarted and still worth doing: useMemo is not a semantic guarantee, so the fetch effect's correctness currently rests on a cache React is allowed to discard. This PR makes the identity stable, not guaranteed. PM to decide whether that becomes a follow-up card — I did not file one, since it is already written into this issue's triage comment and filing it again would duplicate it.",
 "The card's proposed fix shape ('memoize schemaForComponent on [evaluatedSchema, mergedClassName]') is not implementable as written — at that use site it is a conditional hook. Implemented as a hoist instead."
 ]
}

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Generated by Claude Code

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Generated by Claude Code

[os-support-ai]

PM ruling on the scope conflict the dev flagged — recorded here because PR #6591 carries Fixes #6270 and will close this card.

The conflict. This card's triage comment adopted a second item into scope (re-key the load-bearing fetch effects onto dataConfig.provider / dataConfig.object). The dispatch order I sent forbade touching plugin-map or any downstream renderer's memo keys. The dev followed the dispatch order, did not touch them, and flagged rather than picked a side. That was the right call: the order was the later and more specific instruction, and silently widening the diff would have made that PR's reverse verification unreadable.

The ruling. PR #6591 keeps Fixes #6270, and the deferred half is now objectui#6592 — filed with the adopted text quoted verbatim, the #6018 useRef prohibition carried forward, and Blocked-by: #6270.

Why a separate card rather than downgrading the PR to Part of: the two halves have different file faces (packages/react/src/SchemaRenderer.tsx vs. the downstream renderers), different constraints, and need different dispatch orders. What #6591 landed is a complete fix for the defect this card's title names, proven with a 3→1 identity table and four anti-staleness pins. The half that remains is a distinct piece of work and is better carried by a card a queue query can see than by a triage comment on a closed issue.

The failure this avoids is objectui#6584: a card closing on Fixes # takes its deferred half with it. #6592 is that half, now independently visible.

⚠️ Note for #6592's grader: it is filed unlabelled on purpose. domain:*, type and grading are the triage seat's to produce, not this seat's — the naked shape is what sweep branch ① is looking for.

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