Guard macOS Namespace fallback retries

evolution/proposals/BEP-0009-release-infrastructure-and-store-upload-pipeline.md

@@ -112,6 +112,11 @@ The same change also makes the forge itself the release authority: release tags
 - Configure macOS Namespace targets with the Compute API CPU-by-memory shape
   format. `12x28` is the Burrow large macOS baseline; platform-prefixed values
   such as `macos/arm64:8x16` are not accepted by the macOS launcher.
+- Treat macOS shape fallback as part of the release lane rather than as a
+  best-effort debug path. When large shapes are quota-constrained, the
+  dispatcher may try smaller accepted shapes, but every fallback must have a
+  bounded create timeout and additional shapes must reuse the final timeout
+  policy instead of crashing the dispatcher.
 - Keep the shared Linux runner work directory out of macOS bootstraps. The
   dispatcher normalizes macOS runners to `/tmp/forgejo-runner` when the shared
   config points at Linux state paths such as `/var/lib/forgejo-runner`.