docs: retire ADR numbers rather than renumbering the survivors

Also refresh the two stale 0001 names in docs/agents/domain.md.

Author: lesnik512

AGENTS.md

@@ -39,6 +39,11 @@ Every link in `README.md` must be absolute: `https://github.com/modern-python/<r
 or `.../tree/main/<path>` for a directory. Never a relative path: `README.md` is also the PyPI long
 description, and PyPI does not rewrite relative links, so a relative one 404s on the package page.
 
+An ADR's number is a permanent address. Fold a record into another or drop it, but leave its
+number retired rather than renumbering the survivors: the citations that matter most live
+outside this repo — in issue bodies, commit messages, review threads — where no gate can follow
+a rename, so a renumber silently points them at whichever record takes the number next.
+
 ## Code Style
 
 - The core package stays **zero-dependency**; PyYAML is the optional `[yaml]` extra and nothing else

docs/agents/domain.md

@@ -17,7 +17,7 @@ Single-context repo:
 /
 ├── CONTEXT.md
 ├── docs/adr/
-│   ├── 0001-healthcheck-start-period-retries-passthrough.md
+│   ├── 0001-healthcheck-wait-budget-is-not-coupled-to-retries.md
 │   └── 0002-zero-dependency-core.md
 └── compose2pod/
 ```
@@ -32,4 +32,4 @@ If the concept you need isn't in the glossary yet, that's a signal: either you'r
 
 If your output contradicts an existing ADR, surface it explicitly rather than silently overriding:
 
-> _Contradicts ADR-0001 (healthcheck start period retries passthrough), but worth reopening because…_
+> _Contradicts ADR-0001 (the healthcheck wait budget is not coupled to `retries`), but worth reopening because…_