diff --git a/.claude/rules/otto-channels-reference-card.md b/.claude/rules/otto-channels-reference-card.md
index 550354b0e..5d83a34b1 100644
--- a/.claude/rules/otto-channels-reference-card.md
+++ b/.claude/rules/otto-channels-reference-card.md
@@ -55,15 +55,33 @@ Allocating a new monotonically-increasing ID across multi-Otto surfaces
 items if numeric, etc.) requires checking BOTH ambient surfaces — not just
 on-disk state:
 
-1. **On-disk check** — what's currently merged:
+1. **Merged-state check via `origin/main`** — what's currently merged
+   (regardless of local worktree state):
 
    ```bash
-   # Portable across GNU + BSD find (macOS/Linux). The `B-NNNN` pattern only
-   # appears once per filename in practice, so extracting from full paths is safe.
-   find docs/backlog -name "B-*.md" -type f \
-     | grep -oE "B-[0-9]+" | sort -u -t- -k2 -n | tail -3
+   # `git fetch origin` (no branch arg) updates ALL configured remote-tracking
+   # refs reliably; the form `git fetch origin main` updates FETCH_HEAD but
+   # may not refresh refs/remotes/origin/main under all configs (refspec
+   # overrides, partial-clone, etc.).
+   git fetch origin
+   git ls-tree -r origin/main -- docs/backlog/ \
+     | awk '{print $4}' | grep -oE "B-[0-9]+" | sort -u -t- -k2 -n | tail -5
    ```
 
+   **Important**: do NOT use `find docs/backlog -name "B-*.md"` on the local
+   worktree. The local working tree may be on a stale HEAD (detached from
+   an abandoned rebase, on a feature branch that's behind, etc.), which
+   gives misleading "what's free" answers. Empirical anchor: tick 0742Z
+   on 2026-05-15 — Otto-CLI's primary worktree was stuck on detached HEAD
+   `65c7865` from an 8h-stale peer-agent rebase; local `find` showed B-0526
+   as the top, missing B-0527 + B-0528 (which were taken by PRs #3334 +
+   #3342 on `origin/main`). The mis-allocation was caught by Copilot review
+   but reached a public PR-comment first; correction comment had to follow.
+   See [PR #3381](https://github.com/Lucent-Financial-Group/Zeta/pull/3381)
+   (which lands `docs/hygiene-history/ticks/2026/05/15/0742Z.md` carrying
+   the full trace), plus the correction comment on
+   [PR #3323](https://github.com/Lucent-Financial-Group/Zeta/pull/3323).
+
 2. **In-flight check** — what peer Otto is filing right now:
 
    ```bash