docs(tasks): re-validate bracketed follow-up into 3 tasks (OAI-18 decision, streaming-coverage residue, doc-gate fix)

The bracketed planning task's five candidates, re-validated against
the post-bulk tree (0a932e5, all 23 bulk tasks done, 446/568 green):

1. OAI-18 -> review-002-fu-oai18-decision: still key-allowlist-only;
   bulk blockers (yaml/path-item) both landed. Task records the
   enforce-vs-scope-the-advert decision framework from review 002.
2. CON-08/CON-09 close() lever: deferred still (documented v1
   contracts unchanged, no consumer pressure) — not tasked.
3. Cross-crate: CF-001..004 all open in alkcall, no alkhttp-side task;
   PRJ-16 guard already documents its defense-in-depth re-scope
   disposition (no work when CF-004 lands).
4. Stale-comment sweep: mostly absorbed by the bulk (SRV-11 comment
   rewritten in-fix); residue = 3 cargo-doc warnings + WsTimeouts
   redundant Default -> review-002-fu-doc-warnings.
5. ADR-045 version audit: clean (1.4.0 + annotations + test pin).

Post-bulk coverage re-pass (95.89% regions, bulk's new code fully
covered: PRJ-16 guard, body cap, router reorder, batch cap, WS
knobs, OAI-11 node budget all exercised) surfaced one unanticipated
residue -> review-002-fu-stream-error-coverage (forward_stream
build-error arm never exercised on a Sub op; PEM read-failure arms;
over-cap poll_write; SSE split-CRLF edge; from_value structural
rejects; WsTimeouts Default).

Bracketed pass itself marked completed (planning consumed).
taskgraph: 69 valid, no cycles; 3 pending.

tasks/adapters/review-002-fu-oai18-decision.md

@@ -0,0 +1,111 @@
+---
+id: review-002-fu-oai18-decision
+name: OAI-18 advertise-vs-enforce decision — enforce leaf constraints or scope the advert (OAI-18)
+status: pending
+depends_on: []
+scope: moderate
+risk: medium
+impact: component
+level: implementation
+tags: [adapters, review-002, follow-up, from-openapi, from-jsonschema]
+---
+
+## Description
+
+Bracketed follow-up item 1 — the one OAI finding the review-002 bulk
+deliberately deferred (Unit 4 landed OAI-12/13 and the loudness
+cluster; OAI-18 was re-evaluated afterwards per the bracket plan). The
+decision was re-validated against the post-bulk tree (43 commits,
+`0a932e5`+): the deferred status still stands, and this task now
+carries it.
+
+**The gap (review 002 OAI-18, verified at tree `91483a7`):**
+`enforce_input_schema` (`src/adapters/forward.rs:455-499`) enforces a
+**key allowlist** only. The `/schema` surface advertises full JSON
+Schema (`required`, `enum`, `pattern`, `minLength`, value types) via
+`OperationSpec.input_schema`, but at call time:
+
+- `required: [id]` accepts `{}` (the missing key forwards → upstream
+  422 instead of the gateway's own `INVALID_INPUT 422`)
+- a `{"type": "string"}` property sent as an object serializes as JSON
+  text into the query string (or a header value)
+- `enum`/`minimum`/`pattern` are never consulted
+
+Advertise/enforce drift: the contract the gateway publishes is broader
+than the one it defends. The review-001 OAI-02 *unknown-key* vector
+(undeclared keys shaping the request) is closed; this is the
+declared-but-unchecked remainder. Nothing changed this in the bulk —
+re-verified `forward.rs:455-499` is still membership-only at `0a932e5`.
+
+**The decision this task must make** (implement with the decision, or
+record its explicit rejection):
+
+- **(a) Enforce leaf constraints**: compile the full input schema per
+  op with the `jsonschema` crate (already a dependency via
+  `gateway/schema_cache.rs`) and validate peer input at call time,
+  reusing the `PublishSchemaCache` compile-once pattern. This makes
+  advertise == enforce exactly, at the cost of a per-op compile and
+  schema-dialect semantics (2020-12; same dialect publish_schema
+  already uses, so the crate is consistent).
+- **(b) Scope the advert**: instead of enforcing, project a
+  reduced input schema into `/schema` — describe only what is enforced
+  (keys + types, drop `required`/`enum`/`pattern` from what
+  `spec_to_json` advertises) — so the contract and the enforcement
+  match while the *spec* stays the configuration source. (Downside:
+  information loss for well-behaved consumers; the spec-derived
+  detail is genuinely useful documentation for humans.)
+
+The review-002 assessment leaned (a) — the crate already pays the
+compile-cache complexity for `publish_schema`, and the advertise/enforce
+asymmetry is exactly the class of drift review 002 filed as
+[minor→major-class]. Option (b) is legitimate if the assembly-layer
+trust boundary (ADR-066's "specs are trusted configuration") is judged
+to make full-schema enforcement unnecessary belt — but note OAI-02's
+rationale cut the other way: peer *input* is never trusted, and the
+advertised schema is exactly what a peer reads before crafting input.
+
+## Acceptance Criteria
+
+- [ ] A decision recorded (implement one option, or document a third)
+      in ADR-066 with the FWD-17/18/19 decision-section style
+- [ ] If (a): input schemas compile once per registration (cache
+      invalidation mirrors `schema_cache.rs`'s value-keyed scheme);
+      peer input failing leaf constraints → `INVALID_INPUT` 422
+      naming the violated keyword — NOT an upstream round-trip; a spec
+      whose input schema fails to compile fails *import* loudly
+      (fail-closed, matching the publish_schema precedent from
+      review-001's follow-up task)
+- [ ] If (a): the advertised-vs-enforced round-trip test from the
+      review-002 test-gap list lands: construct a doc, import, assert
+      the `/schema`-exported `input_schema` accepts exactly what
+      `build_request` accepts (the missing chain-test that let JS-01
+      and OAI-18 survive two reviews)
+- [ ] If (b): the advert-stripping behavior is tested (required/enum/
+      pattern absent from `/schema` output while the original spec
+      retains them internally) and the module doc + ADR-066 say so
+- [ ] Either way: `cargo test`, `cargo clippy --all-targets --
+      -D warnings`, `cargo fmt --check` pass (`--all-features` if
+      mcp-touched)
+
+## References
+
+- docs/reviews/002-post-remediation-review.md (Part E', OAI-18)
+- src/adapters/forward.rs:455-499 (the key-allowlist), src/gateway/schema_cache.rs (the compile-once pattern to reuse)
+- docs/architecture/decisions/066-from-jsonschema-as-http-adapter.md (the section to extend), /decisions/023-operation-error-schemas.md
+- tasks/adapters/review-002-yaml-normalization.md and review-002-oai13-path-item-wildcards.md (the post-bulk advertised-schema surface this decision was deferred against)
+- docs/reviews/002-post-remediation-review.md Test-gap 10 (the round-trip test)
+
+## Notes
+
+This was bracketed explicitly because review-002-yaml-normalization
+and review-002-oai13-path-item-wildcards both change the
+advertised-schema surface (wildcards now project with payload schemas;
+path-item parameters merge in). Those landed; the decision is now
+unblocked and the surface is stable. The jsonschema dialect question
+is settled by precedent (`PublishSchemaCache` compiles against the
+same crate). If (a) is chosen, watch one interaction: the
+`HEADER_PARAM_IN_MARKER`-decorated and `body` properties are
+peer-visible schema extensions — the compiled validator must accept
+them as ordinary properties (they are), and `additionalProperties:
+true` semantics must keep working (opt-in catch-all — the compiled
+validator gives you this for free).