docs(spec): the ledger entry names the flat better-auth error body, not an ADR-0112 envelope

`entries/semantic/18.client-oauth-applications-delete-void.ts` listed "same
ADR-0112 error envelope" among the things this change leaves untouched on the
wire. The operative claim is true — the error bodies do not move — but the
label is wrong for this route. `POST {auth}/oauth2/delete-client` is
better-auth's, and its 404 answers the vendor's FLAT shape,
`{"error_description":"client not found","error":"not_found"}`, not
ObjectStack's nested ADR-0112 envelope. The repo states the distinction
verbatim at
`packages/plugins/plugin-auth/src/admin-remove-user-gate-ordering.test.ts:86`:
"ObjectStack's ADR-0112 envelope nests it; better-auth's flat shape does not".

Worth a correction rather than a follow-up because the string is
consumer-facing: entries prefixed `18.` project into `spec-changes.json` and
`docs/protocol-upgrade-guide.md` when major 18 becomes current, and a reader
told "same ADR-0112 error envelope" would write a nested read against a flat
body. What the entry asserts is unchanged; only the mislabel moves.
`migrations/registry.ts` is regenerated by `gen:migration-registry`, never
hand-edited, and a re-run at this head is a byte no-op — the entry is indexed,
not merely present.

This branch squashes, so its commit messages enter `main` verbatim and this
one carries the current state of the disposition question. The ADR-0087
disposition IS claimed: the changeset carries
`adr-0087: registered client-oauth-applications-delete-void`, and
`check-adr-0087-registration` exits 0 at this head, printing "1
declared-breaking changeset(s), each carrying an ADR-0087 disposition" against
that marker. An earlier message on this branch states the disposition is not
claimed and that the gate is expected to red until a maintainer settles it;
that expectation is superseded — the maintainer settled it as ruling D on
#15674 (2026-09-05), and this class routes through ADR-0087 `registered`.

Measured at this head, exit codes captured by redirect-then-capture:
`gen:migration-registry` re-run byte no-op (`git hash-object` unchanged),
`check:spec-changes` "spec-changes.json is up to date.", `check:upgrade-guide`
"protocol-upgrade-guide.md is up to date.", `check:adr-0087-registration`
self-test (332 assertions) and main both exit 0, the spec migrations suite 117
passed, `@objectstack/spec` typecheck exit 0, and `check:nul-bytes`,
`check:doc-authoring`, `check:spec-parsed-alias` exit 0.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01D47qPfEWVPmhguWgBZCi5N

Author: claude

packages/spec/src/migrations/entries/semantic/18.client-oauth-applications-delete-void.ts

@@ -51,7 +51,9 @@ export const entry: SemanticMigration = {
     + 'now reads the body as text, returns on the empty case, and still parses (and still '
     + 'throws on) a non-empty one — so the ONLY behaviour that moved is the zero-byte '
     + 'case, which is the defect itself. THE WIRE IS BYTE-IDENTICAL: same route, same '
-    + 'request body, same status codes, same ADR-0112 error envelope; no Zod schema and '
+    + 'request body, same status codes, same error bodies — which on this route are '
+    + 'better-auth\'s FLAT `{ error, error_description }`, NOT ObjectStack\'s nested '
+    + 'ADR-0112 envelope; no Zod schema and '
     + 'no `packages/spec` declaration moves, no authorable key and no stored '
     + 'representation is involved, so a raw-HTTP caller is unaffected and '
     + '`objectstack migrate meta` has nothing to rewrite. This is registered rather than '

packages/spec/src/migrations/registry.ts

@@ -6180,7 +6180,9 @@ const step18: MigrationStep = {
         + 'now reads the body as text, returns on the empty case, and still parses (and still '
         + 'throws on) a non-empty one — so the ONLY behaviour that moved is the zero-byte '
         + 'case, which is the defect itself. THE WIRE IS BYTE-IDENTICAL: same route, same '
-        + 'request body, same status codes, same ADR-0112 error envelope; no Zod schema and '
+        + 'request body, same status codes, same error bodies — which on this route are '
+        + 'better-auth\'s FLAT `{ error, error_description }`, NOT ObjectStack\'s nested '
+        + 'ADR-0112 envelope; no Zod schema and '
         + 'no `packages/spec` declaration moves, no authorable key and no stored '
         + 'representation is involved, so a raw-HTTP caller is unaffected and '
         + '`objectstack migrate meta` has nothing to rewrite. This is registered rather than '