The records pointed at branches that no longer exist, and two fixes had no sequel

Three issues named the branch that fixed them, and a branch is deleted
when it merges — so every `fixed-by:` was a pointer that resolved to
nothing by the time anyone followed it. They name commits and pull
requests now, and playbook 03 says to.

Two records were missing the thing a reader arrives for. 146 did not say
that one of its fixes crash-looped the control plane on a running mesh,
which is the whole reason the delivery subject carries the stream and the
raise path was the only one exercised. 151 did not say that 152 removed
the false reasons its roster moved, or that it stays open for the real
ones.

ADR 0080 enumerates what cycle.py enforces and named four things; it
enforces five. A progressive insight names the fifth — the decision
stands, the list had gone stale. The checks README and playbook 03 gained
the same rule, and 155 points at all three.

00-META/process/03-issues.md

@@ -21,7 +21,12 @@ incident someone must **clear**.
 
 ## Steps
 
-1. Take the next free number. Create `04-ISSUES/NNN-short-name/00-report.md`:
+1. Take the next free number — **across `main` and every open pull request**, not `main` alone.
+   Work sits on unmerged branches for days, so two people both reading `main` allocate the same
+   number; it happened twice in one hour between two machines, and the second collision reached
+   `main` with every check passing (issue 155). `cycle.py` now refuses two records sharing a number,
+   which catches a collision but does not prevent one. Create
+   `04-ISSUES/NNN-short-name/00-report.md`:
 
    ```yaml
    ---
@@ -42,6 +47,14 @@ incident someone must **clear**.
 ## Rules
 
 - Closed issues are never deleted — they are the mesh's symptom-to-component memory.
+- `fixed-by:` names something that will still exist: a commit or a pull request, never a branch. A
+  branch is deleted when it merges, so a branch name there is a pointer that resolves to nothing by
+  the time anybody follows it.
+- A fix that turns out to have broken something else is written back into the record that asked for
+  it, pointing at the new issue. Somebody arriving at a record to learn why the code is the way it
+  is must not have to already know there was a sequel.
+- Renumbering a collision happens once, in the branch that lands last. Renumbering a branch whose
+  author is still pushing only moves the race.
 - An issue whose answer is a general lesson should also be written to the knowledge base, so
   the next person searching a symptom finds it. Both, not either.
 - `status: wontfix` is legitimate and requires a sentence saying why.