diff --git a/docs/hygiene-history/ticks/2026/05/15/1043Z.md b/docs/hygiene-history/ticks/2026/05/15/1043Z.md
new file mode 100644
index 0000000000..e97bf3eb35
--- /dev/null
+++ b/docs/hygiene-history/ticks/2026/05/15/1043Z.md
@@ -0,0 +1,38 @@
+| 2026-05-15T10:43:00Z | claude-opus-4-7 | 596e842c | shard: peer-Otto PR #3414 merged (mutex substrate landed); my PR #3415 templated threads addressed | (PR #3418) | B-0530 mitigation now on main via peer-Otto's parallel work; routine continues |
+
+# Tick 1043Z — peer-Otto mutex substrate landed; PR #3415 templated threads
+
+## Headline
+
+- **Peer-Otto's PR [#3414](https://github.com/Lucent-Financial-Group/Zeta/pull/3414)** (their 1036Z shard documenting "mutex empirically operational") MERGED → `f5ef4d7`. The B-0530 cron-sentinel-mutex mitigation peer-Otto filed earlier is now operationally landed.
+- My PR [#3415](https://github.com/Lucent-Financial-Group/Zeta/pull/3415) (1033Z shard) picked up 2 templated threads: stale `(PR TBD)` + cross-PR temporality (1035Z file). Both resolved via templated replies.
+- Cron sentinel `596e842c` armed.
+
+## Δ since 1040Z (qualitative)
+
+- Merges: peer-Otto's PR #3414 + (mine wait-ci)
+- Threads: 2 routine templated on my #3415
+- In-flight (mine): PR #3415 (post-thread-fix) + PR #3416 + this tick's PR
+- B-0530 mutex now on main
+
+## Substrate-honest observations
+
+### B-0530 mutex landed via peer-Otto's parallel work
+
+The deferred candidate "claude-loop substrate investigation OR mutex implementation" — peer-Otto did the latter. The B-0530 mitigation row I filed in MY session (PR #3530 earlier... actually peer-Otto filed B-0530 in PR #3372) has now been implemented + the substrate-honest "mutex empirically operational" tick landed via PR #3414.
+
+This is the **two-Otto-coordination dividend**: substantive substrate work that would have been my deferred candidate is now done by peer-Otto. I didn't need to start the investigation; the work landed.
+
+Validates the design: divergent parallel work, convergent substrate via git/main. Both sessions benefit.
+
+### Templated thread iteration continues unchanged
+
+PR #3415 had 1 stale `(PR TBD)` + 1 cross-PR temporality (1035Z). Same routine variants. Per-thread response time ~30s.
+
+## Cron sentinel
+
+`596e842c` armed.
+
+## Next
+
+Cron-driven.