shard(tick): 2113Z — duplicate-ID audit class (mechanizes 2108Z deferred candidate)

docs/hygiene-history/ticks/2026/05/14/2113Z.md

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+# Tick 2026-05-14T21:13Z — duplicate-ID audit class (mechanizes the B-0329 catch from 2108Z)
+
+## Refresh (step 1)
+
+- Cron sentinel `12fb713e` live.
+- Prior-tick PR merges this batch:
+  - **#3245** (shard 2055Z) — MERGED as `10f35d7`
+  - **#3247** (BACKLOG.md regen + B-0329→B-0520 renumber) — MERGED as `d04481b`
+- #3246 / #3249 still wait-ci with autoMerge armed.
+
+## Holding discipline (step 2)
+
+Not Standing-by. Real-dependency-wait bounded. Per never-be-idle: the
+2108Z shard filed a deferred audit-discipline candidate
+(`audit-backlog-id-uniqueness.ts`); acting on it.
+
+## Work (step 3) — mechanize the B-0329 catch
+
+Per `.claude/rules/skill-router-as-substrate-inventory.md`: check before
+duplicating. Existing `tools/hygiene/audit-backlog-items.ts` already
+audits 7 ID-integrity classes (broken edges, orphan rows, top-blocked,
+etc.). The 8th — duplicate IDs — composes naturally. Extended rather
+than minted new.
+
+Added `reportDuplicateIds(rows)` after `reportMergedCandidates(...)`:
+
+- Groups rows by `id`; reports any group with `length > 1`
+- Output format mirrors sibling `report*` functions (`## 8` section,
+  per-group listing, resolution note pointing at `renumbered_from`
+  breadcrumb pattern)
+- Summary block gets a new line: `Duplicate-ID groups: N`
+
+Live verification: on `origin/main` (before PR #3247 merged earlier
+this batch), the audit reported **1 duplicate-ID group** — exactly the
+B-0329 collision Copilot caught. Now that #3247 has merged renaming
+the file to B-0520, the next run will report 0.
+
+PR **#3250** opened; auto-merge armed.
+
+## Verify (step 4)
+
+- `bun tools/hygiene/audit-backlog-items.ts` runs cleanly + reports
+  the duplicate-ID class
+- Class output format matches sibling functions (style consistency)
+- `tsc --noEmit` clean
+- Composite branch-guard + `gh pr create --head` used
+
+## Shard (step 5)
+
+This file.
+
+## CronList (step 6)
+
+Sentinel `12fb713e` armed; one entry, recurring.
+
+## Visibility (step 7)
+
+- **PR #3250** (feat(hygiene) duplicate-ID audit) — wait-ci, autoMerge armed
+- **#3246 / #3249** (shards 2059Z / 2108Z) — still wait-ci, autoMerge armed
+- **#3245 / #3247** merged this batch
+
+## Session running tally (after this tick)
+
+- Merged (16): #3221 + #3222 + #3226 + #3227 + #3228 + #3231 + #3232 +
+  #3233 + #3235 + #3237 + #3239 + #3240 + #3244 + #3245 + #3247 + #3248
+- Wait-ci (4): #3246 + #3249 + #3250 + this shard's PR
+
+## Notes for future-Otto
+
+The lifecycle of this defense:
+
+1. **2059Z tick** — Copilot caught the B-0329 collision on PR #3247
+2. **2108Z tick** — fixed via renumber (B-0329 → B-0520) + filed audit-
+   discipline candidate
+3. **THIS tick (2113Z)** — mechanized the catch as the 8th audit class
+4. **Future ticks** — `audit-backlog-items` reports duplicate-ID groups
+   at every run; CI / cadence integration is a separate B-row if needed
+
+The pattern: review-time catch → out-of-band fix → mechanization in the
+next tick. Three-step propagation from a single Copilot review thread.
+
+Composes with the broader audit-extension discipline: when a known-gap
+fix mechanizes a class of bug, extend an existing audit tool rather
+than minting a new one. The `audit-backlog-items` 7→8 class growth is
+the right shape.