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+# Tick 2026-05-16T15:47Z — B-0462 cascade landed; peer-contamination caught by branch-discipline
+
+## Refresh
+
+- Cron sentinel: `23b8588a` still armed (`* * * * *` + `<<autonomous-loop>>`).
+- `cron-sentinel-mutex --json` → peers still detected (saturation persists from
+  prior tick).
+- `gh api rate_limit` → **565 GraphQL remaining**; reset in **10 min**.
+  Still extreme cost-aware tier.
+- `git fetch origin main` → main HEAD moved from `0e94bdb` → `24a76dc`
+  (delta: 1 merge into main).
+
+## Step-2 Holding discipline
+
+NOT applicable — substantive observation identified at step 1.
+
+## Cascade confirmation (1535Z chain completion)
+
+The 1535Z tick observed PR #3897 (B-0462 7th cycle close-row) freshly opened
+with auto-merge armed. This tick confirms the chain landed:
+
+| Artifact | 1535Z disposition | 1547Z disposition |
+|---|---|---|
+| [PR #3897](https://github.com/Lucent-Financial-Group/Zeta/pull/3897) (B-0462 close) | OPEN, auto-merge armed, 25 checks | **MERGED** at `4443c09` |
+| [PR #3898](https://github.com/Lucent-Financial-Group/Zeta/pull/3898) (1535Z tick shard) | OPEN, auto-merge armed | OPEN, MERGEABLE, auto-merge armed |
+
+12-minute cycle from PR-open → MERGED is consistent with typical Zeta CI
+duration (5-15 min depending on matrix shape).
+
+## Peer-contamination caught by branch-discipline
+
+`git branch --show-current` at tick start reported
+`otto-cli-b0457-close-2026-05-16-1542z` — **peer Otto-CLI's branch**, not mine.
+The primary worktree's HEAD had silently moved while my session was idle
+between cron fires.
+
+This is the canonical multi-Otto-branch-state-contamination pattern in
+[B-0519](../../../../backlog/P3/B-0519-multi-otto-branch-state-contamination-rca-2026-05-14.md).
+The catch:
+
+- `git status --short` returned empty → working tree clean → no file
+  contamination this time
+- `git branch --show-current` made the HEAD-shift visible BEFORE any
+  mutating operation
+- `git switch -c otto-cli-tick-shard-1547z-cascade-confirm-2026-05-16 origin/main`
+  recovered cleanly without `git worktree add` (would have contended on
+  `.git/objects/pack` per peer-saturation discipline)
+
+The substrate-honest takeaway: the `git branch --show-current` discipline
+documented in
+[`zeta-expected-branch.md`](../../../../../.claude/rules/zeta-expected-branch.md)
+is the primary catch (not the `ZETA_EXPECTED_BRANCH` env-var hook, which can't
+survive cross-tool-call shell-environment evaporation).
+
+## Step-3 Speculative work
+
+No additional substantive landing this tick — the cascade-confirmation
+observation IS the value-add (substrate-or-it-didn't-happen applies to
+documented-confirmations as well as to new-substrate).
+
+Avoided burning rate-limit budget on PR #3897 verification work that
+`git log origin/main` already established for free.
+
+## Files
+
+- [docs/hygiene-history/ticks/2026/05/16/1547Z.md](.) (this file)
+
+## Real-dependency-waits active
+
+- [PR #3898](https://github.com/Lucent-Financial-Group/Zeta/pull/3898)
+  (1535Z tick shard) — auto-merge armed, awaiting CI completion
+  (~5-15 min from open at 15:35Z; likely landing this tick window).
+
+## Cost summary
+
+- ~5 GraphQL calls consumed (1× rate_limit-REST-free, 1× pr-view-#3898,
+  1× pr-list-B-0457-search, ~2× pr-create + pr-merge-auto for this tick).
+- Remaining target: ~555 GraphQL pre-reset.
+
+## Visibility signal
+
+Cascade chain from 1531Z → 1535Z → 1547Z complete. PR #3897 merged.
+PR #3898 auto-merging. Peer-contamination on primary worktree caught and
+worked around without contention. This tick's deliverable IS the
+cascade-confirmation shard (PR to be opened next).
+
+## Composes with
+
+- [`docs/AUTONOMOUS-LOOP-PER-TICK.md`](../../../../AUTONOMOUS-LOOP-PER-TICK.md)
+- [`.claude/rules/zeta-expected-branch.md`](../../../../../.claude/rules/zeta-expected-branch.md)
+  (the branch-discipline that caught the HEAD-shift)
+- [`.claude/rules/refresh-world-model-poll-pr-gate.md`](../../../../../.claude/rules/refresh-world-model-poll-pr-gate.md)
+  (extreme-cost-aware tier behavior; `git log` over `gh pr view`)
+- [B-0519](../../../../backlog/P3/B-0519-multi-otto-branch-state-contamination-rca-2026-05-14.md)
+  (multi-Otto contamination RCA)
+- [Tick 1535Z shard](1535Z.md) (the prior tick this one confirms)
+- PR #3897 (B-0462 close, MERGED `4443c09`)
+- PR #3898 (1535Z tick shard, OPEN auto-merging)