validatord: /v1/validate + /v1/iterate HTTP surface (port 3221)

Closes the last "Go primary" backlog item in
docs/ARCHITECTURE_COMPARISON.md. Go now owns the entire validator
path end-to-end — no Rust dep for staffing safety net.

Architecture: cmd/validatord on :3221 hosts both endpoints. Calls
chatd directly for the iterate loop's LLM hop (no gateway
self-loopback like the Rust shape). Gateway proxies /v1/validate +
/v1/iterate to validatord.

What's in:
- internal/validator/playbook.go — 3rd validator kind (PRD checks:
  fill: prefix, endorsed_names ≤ target_count×2, fingerprint required)
- internal/validator/lookup_jsonl.go — JSONL roster loader (Parquet
  deferred; producer one-liner documented in package comment)
- internal/validator/iterate.go — ExtractJSON helper + Iterate
  orchestrator with ChatCaller seam for unit tests
- cmd/validatord/main.go — HTTP routes, roster load, chat client
- internal/shared/config.go — ValidatordConfig + gateway URL field
- lakehouse.toml — [validatord] section
- cmd/gateway/main.go — proxy routes for /v1/validate + /v1/iterate

Smoke: 5/5 PASS through gateway :3110:
  ✓ playbook happy path
  ✓ playbook missing fingerprint → 422 schema/fingerprint
  ✓ phantom candidate W-PHANTOM → 422 consistency
  ✓ unknown kind → 400
  ✓ roster loaded with 3 records

go test ./... green across 33 packages.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/ARCHITECTURE_COMPARISON.md

@@ -51,6 +51,7 @@ Don't:
 | _open_ | Drop Python sidecar from Rust aibridge | Universal-win architectural cleanup. ~200 LOC, removes 1 runtime + 1 process. |
 | 2026-05-02 | **Port Rust materializer to Go (transforms.ts) — DONE** | `internal/materializer` + `cmd/materializer` + `materializer_smoke.sh`. Ports `transforms.ts` (12 transforms) + `build_evidence_index.ts`. Idempotency, day-partition, receipt. 14 tests green; on-wire JSON matches TS so both runtimes interoperate. |
 | 2026-05-02 | **Port Rust replay tool to Go — DONE** | `internal/replay` + `cmd/replay` + `replay_smoke.sh`. Ports `replay.ts` retrieve → bundle → /v1/chat → validate → log. Closes audit-FULL phase 7 live invocation on Go side. 14 tests green; same `data/_kb/replay_runs.jsonl` shape (schema=replay_run.v1) as TS. |
+| 2026-05-02 | **`/v1/validate` + `/v1/iterate` HTTP surface — DONE** | `cmd/validatord` (port 3221) hosts both endpoints. `internal/validator` gains `PlaybookValidator` (3rd kind), JSONL roster loader, and the `Iterate` orchestrator + `ExtractJSON` helper. Gateway proxies `/v1/validate` + `/v1/iterate` to validatord. Closes the last "Go-primary" backlog item (architecture_comparison.md item #7). 30+ tests + `validatord_smoke.sh` 5/5 PASS. |
 | _open_ | Decide on Lance vector backend | Defer until corpus exceeds ~5M rows. |
 | _open_ | Pick Go primary vs Rust primary | Both viable. Go has perf edge after today; Rust has production deploy + producer-side completeness. |
 
@@ -270,9 +271,9 @@ The list below is a working backlog. Move items to "Decisions tracker"
 
 ### If keeping Go primary
 
-5. **Port materializer** (highest leverage — unblocks full Go pipeline). ~500-800 LOC.
-6. **Port replay tool** (closes audit-FULL phase 7 live invocation). ~400-600 LOC.
-7. **Port `/v1/validate` + `/v1/iterate` HTTP surface** for the now-Go-side validators. ~200 LOC.
+5. ✅ **Port materializer** — DONE 2026-05-02 (`cmd/materializer`).
+6. ✅ **Port replay tool** — DONE 2026-05-02 (`cmd/replay`).
+7. ✅ **Port `/v1/validate` + `/v1/iterate` HTTP surface** — DONE 2026-05-02 (`cmd/validatord`).
 8. **Skip Lance** until corpus growth demands it (>5M rows).
 9. **Keep chatd, observer fail-safe, role gate, multi-corpus matrix** — real Go wins worth preserving.
 
@@ -314,6 +315,7 @@ Append entries here when this doc gets updated. One-line entries; link to commit
 - 2026-05-01 (later) — coder/hnsw v0.6.1 panic real fix landed: vectord lifts source-of-truth out of coder/hnsw via `i.vectors` side store + recover wrappers + rebuild fallback. Re-run multitier 60s/conc=50: 0 failures across 19,622 scenarios. STATE_OF_PLAY invariant added to "DO NOT RELITIGATE".
 - 2026-05-02 — Substrate fix verified at original failure-surfacing scale. Multitier 5min @ conc=50: 132,211 scenarios at 438/sec, 6/6 classes at 0% failure (was 4/6 pre-fix). Throughput drop (1,115 → 438/sec) is the honest cost of the formerly-broken scenarios doing real HNSW Add work. STATE_OF_PLAY refreshed to 2026-05-02.
 - 2026-05-02 — Materializer + replay tool ported from Rust legacy to Go (`internal/materializer` + `internal/replay`, both with CLI + smoke + tests). Both runtimes now produce the same `data/evidence/YYYY/MM/DD/*.jsonl` and `data/_kb/replay_runs.jsonl` shapes; Go side no longer needs Bun for these phases.
+- 2026-05-02 — `/v1/validate` + `/v1/iterate` HTTP surface ported as `cmd/validatord` on `:3221`. Closes the last "If keeping Go primary" backlog item — Go now owns the entire validator path end-to-end (no Rust dep for staffing safety net). 5/5 smoke probes via gateway :3110.
 
 ---