fix(renderer): derive SECTION_2D_UNIFORM_SLOT_COUNT from the slot index

[BIMvoice]

Summary

• SECTION_2D_UNIFORM_SLOT_COUNT (packages/renderer/src/shaders/section-2d-overlay.wgsl.ts) sized the shared section-2D-overlay uniform buffer with a hand-written 6. SECTION_2D_UNIFORM_SLOT_INDEX, defined just above it, maps each draw site to its slot and currently has 6 keys — the two agree today, but nothing enforces it. A new key added to the index type-checks (a property access forces the key to exist) while the count stays whatever was last typed, leaving the buffer one slot short of what the new draw site addresses.
• SECTION_2D_UNIFORM_SLOT_COUNT is now Object.keys(SECTION_2D_UNIFORM_SLOT_INDEX).length, so the two can no longer drift.
• Added a test in section-2d-overlay-lifecycle.test.ts pinning the count equal to the index's key count, as a backstop in case a future refactor reintroduces a literal.

Verification the test is non-vacuous

Confirmed by hand before committing (not left in the diff): with the old literal 6 restored and a 7th key added to the index, the new test failed (not ok 1 - equals the number of entries in SECTION_2D_UNIFORM_SLOT_INDEX). Reverting the perturbation and re-applying the derive fix turned it green again.

Other literals checked

Grepped every .ts/.tsx reference to both symbols. No other hand-written literal is tied to the slot count — the other consumers (section-2d-overlay.ts, section-2d-overlay-lifecycle.test.ts) all read SECTION_2D_UNIFORM_SLOT_COUNT itself, so they automatically track the fix.

Test plan

• cd packages/renderer && npx tsx --test src/*.test.ts — 1144 pass, 0 fail, 1 pre-existing skip
• node scripts/check-module-size.mjs — OK
• node scripts/check-source-text-assertions.mjs — OK

Refs #3342

https://claude.ai/code/session_01QPHChk3Ve9N519A4kY7436

Summary by CodeRabbit

• Bug Fixes
  • Improved reliability of 2D overlay rendering by keeping uniform slot configuration automatically synchronized.
• Tests
  • Added coverage to detect mismatches between configured uniform slots and their index definitions.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 2d273b4d-b842-4b99-8376-d0a489676fa7

📥 Commits

Reviewing files that changed from the base of the PR and between 5a431e5 and 3e09926.

📒 Files selected for processing (3)

• .changeset/section-2d-slot-count-derived.md
• packages/renderer/src/section-2d-overlay-lifecycle.test.ts
• packages/renderer/src/shaders/section-2d-overlay.wgsl.ts

Included review availability: Your plan provides up to 2 included reviews per hour; 0 remain after this review.

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📝 Walkthrough

Walkthrough

The renderer now derives SECTION_2D_UNIFORM_SLOT_COUNT from SECTION_2D_UNIFORM_SLOT_INDEX. A test verifies that both values remain equal. A patch changeset documents the update.

Changes

Renderer slot count

Layer / File(s)	Summary
Derive and verify slot count packages/renderer/src/shaders/section-2d-overlay.wgsl.ts, packages/renderer/src/section-2d-overlay-lifecycle.test.ts, .changeset/section-2d-slot-count-derived.md	The slot count is derived from the slot index length. A test checks their equality. The changeset records the patch release.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Merge Risk: ⚪ Minimal · up to 3e099

The uniform buffer slot count is now derived from the slot index and covered by a regression test; no actionable merge-blocking risk remains after normal checks and review.

Suggested reviewers: louistrue

Poem

A rabbit counts slots in a tidy row
No hardcoded six remains below
The index and count now agree
Tests guard their harmony
Hop, hop, shipped cleanly!

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 2 files. (1 skipped: 1 …	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: deriving SECTION_2D_UNIFORM_SLOT_COUNT from the slot index in the renderer.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

Full details: Docstring Coverage

Explanation

Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 2 files. (1 skipped: 1 unsupported.)

• Fix all pre-merge checks with AI

✨ Finishing Touches 💡 1

📝 Generate docstrings 💡

• Create stacked PR
• Commit on current branch

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[github-actions]

Viewer benchmark

✅ No threshold regressions detected.

01_Snowdon_Towers_Sample_Structural(1).ifc

Baseline recorded 2026-07-01T20:31:05.538Z on github-actions ubuntu-latest, viewer-benchmark-ci (headless Chrome, SwiftShader ANGLE), production build.

Metric	Current	Baseline	Delta	Threshold	Status
firstBatchWaitMs	1853ms	2905ms	-36.2%	+50%	✅
firstVisibleGeometryMs	2717ms	3652ms	-25.6%	+50%	✅
streamCompleteMs	3101ms	3598ms	-13.8%	+50%	✅
spatialReadyMs	1460ms	1032ms	+41.5%	+50%	✅
metadataCompleteMs	2025ms	3063ms	-33.9%	+50%	✅
totalWallClockMs	3600ms	3700ms	-2.7%	+50%	✅

AC20-FZK-Haus.ifc

Baseline recorded 2026-07-01T20:30:59.972Z on github-actions ubuntu-latest, viewer-benchmark-ci (headless Chrome, SwiftShader ANGLE), production build.

Metric	Current	Baseline	Delta	Threshold	Status
firstBatchWaitMs	373ms	1075ms	-65.3%	+50%	✅
firstVisibleGeometryMs	1537ms	1572ms	-2.2%	+50%	✅
streamCompleteMs	1554ms	1980ms	-21.5%	+50%	✅
spatialReadyMs	1081ms	915ms	+18.1%	+50%	✅
metadataCompleteMs	1270ms	1392ms	-8.8%	+50%	✅
totalWallClockMs	1800ms	3300ms	-45.5%	+50%	✅

Refresh the baseline from a CI run: dispatch the Benchmark workflow with record_baseline, download the benchmark-baseline artifact, and commit baseline.json (see tests/benchmark/README.md).