Surfaced reviewing #607. Both the plugin entry-prefix exemption (#582) and literal reservePath claims mark a URL subtree WAC-exempt, but the LDP write wildcards (PUT/POST/PATCH/DELETE '/*') sit beneath them. So a request under an exempt subtree that the plugin did not register a handler for falls through to the LDP layer with WAC already skipped.

Core already recognizes this exact class for /.well-known/* and installs explicit 405 blocks (src/server.js ~850–895): "without these blocks the wildcard write handlers would still accept unauthenticated writes under this namespace." The app-subtree mechanisms don't have the equivalent guard.

Status after #607

#607 method-gates reservePath (read-only by default), which closes the unlisted-method vector: a PUT under a read-only /xrpc is now WAC-guarded. Verified.

Residual, not yet closed:

• A widened method at an unhandled path (PUT /api/unhandled when a shim reserved /api with methods:['PUT'] but only handles /api/echo) still routes into the WAC-skipped LDP layer. In a bare pod it 500s (no container) rather than writing, but that's environment-dependent, not a guarantee.
• The entry-prefix case (appPaths: WAC-hook exemption for application mount points (plugin seam from #206) #582) has no method gate at all: a plugin mounted at /myapp that doesn't handle PUT /myapp/x falls straight through.

Suggested fix

Register a scoped fallback under each exempt subtree — ALL <prefix> + ALL <prefix>/* → 404/405 — so unhandled requests resolve inside the app's namespace instead of reaching /*. Plugin-registered specific routes stay more specific and win; needs care around plugins that register their own wildcard under the prefix (potential FST_ERR_DUPLICATED_ROUTE). Belongs in its own PR because it changes the #582 mechanism, not just reservePath.

Refs #607, #582.