shard(tick): 2026-05-16T12:36Z — pure-git tier; 2nd multi-Otto contamination in 3 ticks

docs/hygiene-history/ticks/2026/05/16/1236Z.md

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+# Tick 2026-05-16T12:36Z — Otto-CLI
+
+Autonomous-loop cron fire. **Pure-git tier** (GraphQL 0/5000;
+reset in 19 min). Second consecutive multi-Otto contamination
+event in three ticks.
+
+## Refresh result
+
+| Surface | State |
+|---|---|
+| Cron sentinel | `c9705646` armed (healthy) |
+| Rate limit (GraphQL) | **0/5000 — PURE-GIT TIER** (reset in ~19 min) |
+| Rate limit (core) | 4987/5000 |
+| Lior process | 4 (up from 3 last tick — contention rising) |
+| HEAD at tick start | `otto-cli-b0206-audit-2026-05-16-1207z` (PR #3871 branch — bounced back from peer activity) |
+| WT state | clean |
+
+## Multi-Otto contamination — 2nd observation in 3 ticks
+
+| Tick | HEAD at tick start | Note |
+|---|---|---|
+| 12:11Z | `otto-cli-b0206-audit-2026-05-16-1207z` | my branch (active work) |
+| 12:21Z | `otto-cli-b0037.2-audit-2026-05-16-1131z` | peer's branch (MD018 fix work) |
+| 12:36Z | `otto-cli-b0206-audit-2026-05-16-1207z` | back to my branch |
+
+HEAD has moved at least twice in 25 minutes. Confirms the
+B-0519 RCA pattern at high rate. The peer Otto's `fix_branch`
+shell function (PID 75933 observed at 12:21Z) does `git switch
+<branch>` operations against the shared `.git/`, silently
+moving HEAD between any two Bash-tool calls of THIS session.
+
+The discipline that catches it every time: `git branch
+--show-current` at tick start, before any commit. The
+mitigation: `git switch -c <fresh-branch> origin/main` for each
+tick that authors substrate (no contention with peer's
+`git switch`).
+
+## Operational tier picked
+
+**PURE-GIT** (0-200 GraphQL):
+
+- Zero `gh` calls except `gh api rate_limit` (REST, free)
+- Tick shard committed + pushed via pure git
+- PR creation deferred to post-reset tick (~12:55Z+)
+- Counter-with-escalation: pure-git tier branch push counts
+  as concrete-artifact decomposition (per
+  [refresh-world-model-poll-pr-gate.md](../../../../../../.claude/rules/refresh-world-model-poll-pr-gate.md))
+
+## Deferred-PR backlog
+
+Branches pushed-but-unPRed awaiting post-reset bundling:
+
+- `otto-cli-tick-2026-05-16-1221z` (12:21Z shard — contamination observation #1)
+- `otto-cli-tick-2026-05-16-1236z` (this tick — contamination observation #2)
+
+Both can be bundled into a single PR at the next available
+cost-aware tick (single `gh pr create` per branch, or a
+single bundling PR that picks up both via cherry-pick).
+
+Substrate-honest: under sustained peer contention + pure-git
+tier, deferred-PR accumulation is the expected operational
+mode. The shards are preserved on origin (git layer); they're
+just not visible as PRs yet.
+
+## Sentinel + close
+
+`CronList`: `c9705646` armed.
+
+## Visibility signal
+
+- Cron sentinel healthy
+- 2nd multi-Otto contamination observed in 3 ticks (peer cadence
+  ≈ 1 HEAD-move per tick under load)
+- Fresh branch `otto-cli-tick-2026-05-16-1236z` from
+  `origin/main`
+- Pure-git tier: deferred-PR branch pushed, PR creation
+  deferred to ≥12:55Z (post rate-limit reset)
+- Deferred-PR backlog now contains 2 branches (1221z + 1236z)