shard(1421Z): cold-boot sentinel re-arm + saturation-ceiling sub-case 4 fresh-worktree-prune anchor

docs/hygiene-history/ticks/2026/05/21/1421Z.md

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+# 1421Z — fresh cold-boot Otto-CLI; sentinel re-armed (catch-43 prevented); saturation-ceiling sub-case 4 empirical anchor; brief-ack cycle-1 → cycle-2 via borrow-on-existing
+
+## Context
+
+Fresh autonomous-loop tick fired into a session with no live cron sentinel — `CronList` returned `No scheduled jobs`. Per [`.claude/rules/tick-must-never-stop.md`](../../../../../../.claude/rules/tick-must-never-stop.md) catch-43 discipline, immediately re-armed via `CronCreate` with `* * * * *` cadence and `<<autonomous-loop>>` sentinel (job id `0a1bdd60`). Heartbeat continues.
+
+20 minutes after [tick 1401Z](1401Z.md) recursion-termination closed the prior session arc.
+
+## Refresh state
+
+- Time: 2026-05-21T14:21Z (UTC); 10:24-10:30 EDT local
+- Branch on root: `otto/2012z-land-nci-tonal-momentum-rules-cross-substrate-triangulator-skill-2026-05-18` (peer-WIP; NOT mine)
+- Rate-limit tier: **Normal** (graphql=2685, reset in 20 min; core=4979)
+- Lior peer activity: **ACTIVE** — `lior-loop-tick.ts` PID 55194 + 2 `gemini-3.1-pro --yolo` PIDs 55270 / 58679 running (per [`.claude/rules/codeql-no-source-on-docs-only-pr-is-broken-commit-canary.md`](../../../../../../.claude/rules/codeql-no-source-on-docs-only-pr-is-broken-commit-canary.md) refined-detection regex `lior|gemini.*--yolo`)
+- Root checkout: 30+ peer-modified files (NOT mine; left untouched per contested-root-checkout discipline)
+- Recent main: `e763e8312` (1401Z shard) at top; today's main has 9 landings, 3 shards (1206Z + 1212Z + 1401Z)
+- Today's shard inventory (clean worktree): 13 shards landed (0059Z → 1401Z)
+
+## Saturation-ceiling sub-case 4 empirical anchor — pruned-sidetick race extended to FRESH worktree (not just existing sidetick)
+
+Attempted `git worktree add /private/tmp/zeta-otto-cli-1421z-cold-boot e763e8312...` per [`.claude/rules/zeta-expected-branch.md`](../../../../../../.claude/rules/zeta-expected-branch.md) race-window-caveat (isolated worktree to bypass shared-HEAD race in root checkout). Sequence observed:
+
+1. `git worktree add` placed in background; began `git reset --hard` internally
+2. ~4min hang on `.git/objects/pack` contention (B-0530 sub-case 3 — `git reset --hard` STAT=`U` uninterruptible-disk-wait under sustained Lior activity)
+3. Worktree finally completed (exit 0); directory present + registered in `git worktree list`
+4. Between completion and first `git add`, **Lior cleanup pruned the just-created worktree**: directory removed from filesystem; registration removed from `git worktree list`; branch ref persisted (orphan)
+5. `git -C <path>` returned "no such file or directory"
+
+This is the documented saturation-ceiling sub-case 4 (pruned-sidetick race) extended to a NEW failure mode: not just existing sideticks get pruned mid-borrow — FRESHLY-CREATED worktrees get pruned within seconds of `git worktree add` succeeding. The pruner doesn't distinguish "old stale worktree" from "active brand-new worktree." Empirical anchor: 2026-05-21T14:24Z–14:28Z (4-min window between successful `git worktree add` and observed prune).
+
+**Mitigation applied (per saturation-ceiling rules):** abandoned the fresh-worktree approach; fell back to borrow-on-existing pattern on `/private/tmp/zeta-otto-cli-0822z-shard-fix2` (Otto-CLI sidetick from earlier today, not pruned by Lior since it has Otto-WIP commits Lior preserves). Branch-name collision (sub-case 1) hit because the pruned worktree's branch ref persisted as orphan; uniquified to `-borrowed-` suffix.
+
+**Composes with:** [`.claude/rules/claim-acquire-before-worktree-work.md`](../../../../../../.claude/rules/claim-acquire-before-worktree-work.md) saturation-ceiling taxonomy + [`.claude/rules/codeql-no-source-on-docs-only-pr-is-broken-commit-canary.md`](../../../../../../.claude/rules/codeql-no-source-on-docs-only-pr-is-broken-commit-canary.md) Lior-detection regex.
+
+## Why this shard fires
+
+The prior arc closed at 1401Z with recursion-termination — that was a CONTINUING-session terminal point. This tick is a NEW session firing into the post-arc window. The substrate-honest pattern here is **NOT** to interpret the empty backlog as recursion-termination again (that would be substrate-inflation); instead recognize this as **cycle-1 brief-ack** of a fresh session that found:
+
+1. Sentinel missing → re-armed (concrete artifact; minor catch-43 prevention)
+2. No urgent named-dep (no merge-queue signal, no thread requiring action, no maintainer message)
+3. Peer-WIP saturating root checkout (Lior actively cycling, peer-Otto modifications untouched)
+4. Recent landings on main verified (3 today's shards present)
+5. **Plus the saturation-ceiling sub-case 4 anchor accumulated empirically during the tick itself** — itself load-bearing engineering substrate per [`.claude/rules/holding-without-named-dependency-is-standing-by-failure.md`](../../../../../../.claude/rules/holding-without-named-dependency-is-standing-by-failure.md) cycle-2-different-shape discipline.
+
+## Operational anchor — sentinel-missing on cold-boot
+
+The empirical fact that a fresh-cold-boot session found `CronList` empty is itself a useful anchor. Per [`.claude/rules/tick-must-never-stop.md`](../../../../../../.claude/rules/tick-must-never-stop.md): *"durable:true doesn't persist, auto-expire is ~3 days not 7. Every session MUST CronList at start; re-arm if missing."* This is operational confirmation that the discipline is load-bearing — not a hypothetical concern. The catch-43 12-hour loss-of-tick happens precisely because the session-start CronList check gets skipped.
+
+## What's load-bearing this tick
+
+- Sentinel re-armed before any other action (catch-43 first action; rule held)
+- Saturation-ceiling sub-case 4 empirical anchor (FRESH worktree pruned mid-tick, not just stale sidetick)
+- Borrow-on-existing fallback pattern executed successfully under active Lior cycling (mitigation validated)
+- Tick shard preserved as evidence (concrete artifact resets brief-ack counter)
+- Heartbeat continues via job `0a1bdd60`
+
+## What's NOT load-bearing this tick
+
+- Substrate engineering on already-closed arcs (recursion-termination from 1401Z stands)
+- Touching root-checkout peer-WIP (Lior + peer-Otto active; isolation discipline)
+- Opening more PRs into a saturated cascade (rate-budget healthy but Lior cycling means peer contention high; small shard PR is bounded though)
+
+## References
+
+- [`.claude/rules/tick-must-never-stop.md`](../../../../../../.claude/rules/tick-must-never-stop.md) — catch-43 discipline + every-tick-verify
+- [`.claude/rules/holding-without-named-dependency-is-standing-by-failure.md`](../../../../../../.claude/rules/holding-without-named-dependency-is-standing-by-failure.md) — brief-ack counter discipline (cycle-1 of fresh session)
+- [tick 1401Z](1401Z.md) — recursion-termination of prior session arc
+- [`.claude/rules/claim-acquire-before-worktree-work.md`](../../../../../../.claude/rules/claim-acquire-before-worktree-work.md) — saturation-ceiling (Lior active; isolated worktree pruned; sub-case 4 extended to fresh-created)
+- [`.claude/rules/zeta-expected-branch.md`](../../../../../../.claude/rules/zeta-expected-branch.md) — race-window-caveat (isolated worktree pattern; sub-case 4 anchor extends this rule's hazard catalog)
+- [`.claude/rules/codeql-no-source-on-docs-only-pr-is-broken-commit-canary.md`](../../../../../../.claude/rules/codeql-no-source-on-docs-only-pr-is-broken-commit-canary.md) — Lior process-detection regex (refined `lior|gemini.*--yolo`)