Slice ledger checkboxes drifted from delivery reality: W50/W51/W66 unticked, W41–W49 not headings

[The-Running-Dev]

Context

Two independent drifts in design/30-slices.md found while cross-checking the ledger against merged commits and the issue tracker:

1. Delivered units still shown unticked.

Unit	Ledger	Issue	Merged on main
W50	### [ ] W50	#154 CLOSED	(predecessor of W51)
W51	### [ ] W51	#155 CLOSED	✅ 6b573d3 — src/engine/src/kinds/simulation/derived.ts, modifiers.ts exist
W66	### [ ] W66	#209 OPEN, but code merged	✅ a115098 — site/src/play/browser/phone-layout.browser.test.tsx exists

2. W41–W49 are recorded as bullet items (- [x] **W41 — ...**), not as ### [x] W41 headings like every other unit in the file. Of those nine units, gh issue list --search "W4" finds an issue for only W49 (#139, closed). The other eight (W41–W48) have no corresponding issue at all, despite TODO.md marking all nine [x] and delivered.

The most likely cause: whatever produces per-unit issues (/track, per this repo's own convention in .claude/commands/track.md) enumerates ### [ ] Wnn headings, so a unit recorded as a bullet is invisible to it, and a unit whose heading checkbox lags its real status stays open when it shouldn't.

Ask

• Tick [x] for W50, W51, and W66 in design/30-slices.md, and close W66 — The Play Surface on a Phone #209 (W66) referencing the merged commit.
• Convert the nine W41–W49 bullet entries to the same ### [x] Wnn — Title {#wnn} heading format every other delivered unit uses, so enumeration tooling can see them.
• Re-run whatever generates per-unit issues after the format fix, to confirm W41–W48 either get retroactive issues or are explicitly exempted (they predate the issue-per-unit convention).

Origin

Raised in a 2026-08-06 project assessment, cross-referencing design/30-slices.md against git log --grep and gh issue list.

[The-Running-Dev]

Both drifts this issue named are resolved in design/30-slices.md:

• W50, W51, W66 are ### [x] headings (ticked).
• W41–W49 are ### [x] Wnn — Title {#wnn} headings, not bullet items.

Evidence: fixed at a680d0e (PR #243, "Export the W59 experiment surface, and pin §5a's gated-dependsOn consequence").

Closed by W106 (Tracker Evidence Closure) — confirmed already implemented, not new work in this unit.