g5 cutover slice live — first real Bun-frontend traffic to Go substrate

J said "let's go" → "next" (option 3): actual flip via Bun
mcp-server. Done. Real Bun-frontend traffic now reaches the Go
substrate via /_go/* on Bun :3700, routed to the persistent Go
gateway at :4110.

Companion change in /home/profit/lakehouse (Rust legacy):
  mcp-server/index.ts: new /_go/* pass-through, opt-in via
  GO_LAKEHOUSE_URL env var. Off-by-default (returns 503 on
  /_go/* with rationale). Existing /api/* (Rust gateway) path
  unchanged. Committed locally on the demo/post-pr11 branch.

System config:
  /etc/systemd/system/lakehouse-agent.service.d/go-cutover.conf
  adds Environment=GO_LAKEHOUSE_URL=http://127.0.0.1:4110 to
  the systemd-managed Bun service. Reversible via systemctl
  revert lakehouse-agent.

Live verification (operator curl through Bun frontend):
- /_go/health: gateway responds {"status":"ok","service":"gateway"}
- /_go/v1/embed: nomic-embed-text-v2-moe vectors, dim=768
- /_go/v1/matrix/search vs persistent 200-worker corpus:
    rank=0 id=w-43  Brian Ramirez   (Forklift Operator, Springfield IL)
    rank=1 id=w-102 Laura Long      (Forklift Operator, Cleveland   OH)
    rank=2 id=w-101 Terrence Gray   (Forklift Operator, Champaign   IL)
    3/3 role match, top-1 in IL exactly
- /api/health: lakehouse ok (Rust path unchanged — control verified)

What this is NOT:
- Not an nginx flip — devop.live/lakehouse/* still goes through
  /api/* → Rust :3100. /_go/* is parallel slice for opt-in.
- Not a tool-level cutover — each /_go/<path> is a manual choice;
  no automatic mapping of Rust paths to Go equivalents.
- Not a transformation layer — caller sends Go-shaped requests
  (e.g. /_go/v1/embed expects {texts, model}, not {text}).

Three cutover unit properties verified:
- ADDITIVE: zero modification to any existing Bun tool
- REVERSIBLE: unset GO_LAKEHOUSE_URL → /_go/* → 503
- ISOLATED: Rust gateway state unaffected (different port,
  different binary, different MinIO bucket)

This is the cutover slice operators can use to validate Go-side
handlers under realistic frontend conditions before any
production-traffic flip. Next step (deferred): pick a specific
mcp-server tool to optionally route through Go with response-
shape adapter — that's a product-visible flip rather than this
infrastructure-visible slice.

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

STATE_OF_PLAY.md

@@ -272,7 +272,8 @@ a steady state. Future items will land here as production triggers fire.
 | (scrum) | 3-lineage scrum on `434f466..0d4f033` (post_role_gate_v1). Convergent finding (Opus + Kimi): `DecodeIndex` lost nil-meta items across persistence. **Fixed** by bumping envelope version 1→2 with explicit `IDs []string` field; v1 envelopes still load via meta-key fallback. Opus-only real bugs also actioned: `handleMerge` non-`ErrIndexNotFound` nil-deref, `mathLog` dead wrapper removed, bubble sort → `sort.Slice`. False positives rejected after verification (Kimi rollback misreading + Opus stale-comment claim). 2 new regression tests lock the v2 round-trip + v1 backward-compat. Disposition: `reports/scrum/_evidence/2026-05-01/verdicts/post_role_gate_v1_disposition.md`. |
 | (audit-full port) | **Audit-FULL pipeline** (phases 0/3/4) ported from `scripts/distillation/audit_full.ts`. `internal/distillation/audit_full.go` + `cmd/audit_full` CLI. 6 ported required-check classes; 4 phases (1, 2, 5, 6, 7) deferred — depend on broader Rust pieces (materializer / replay / run-summaries) not yet ported. **Cross-runtime byte-equal verdict on live data**: Go-side audit-full against `/home/profit/lakehouse` produced p3_*/p4_* metrics IDENTICAL to the last Rust-emitted `audit_baselines.jsonl` entry (all 8 metrics match: p3_accepted=386, p3_partial=132, p3_rejected=57, p3_human=480, p4_sft_rows=353, p4_rag_rows=448, p4_pref_pairs=83, p4_total_quarantined=1325). 6 new tests + the live-data probe captured in `reports/cutover/audit_full_go_vs_rust.md`. |
 | (audit-full skips fixed) | **Phases 1/2/5/7 unskipped** (2026-05-01) — port reduced from 4 deferred phases to 1. **Phase 1**: invokes `go test ./internal/distillation/...` via exec.Command (Go equivalent of Rust's `bun test`). **Phase 2**: reads `data/evidence/` and tallies rows + tier-1 source hits as an observer (doesn't re-run the materializer; emits `p2_evidence_rows`/`p2_evidence_skips` metrics). **Phase 5**: reads `reports/distillation/{run_id}/summary.json` + 5 stage receipts; validates schema_version + run_hash sha256 + git_commit hex. **Phase 7**: reads `data/_kb/replay_runs.jsonl`; tail-row JSON parse check. Only **Phase 6** remains skipped (Rust `acceptance.ts` is a TS-only fixture harness; porting fixtures + invariant runner is its own ADR). Live-data probe: 12/12 required checks PASS, `p2_evidence_rows=1055` byte-equal to Rust `summary.json` `collect.records_out`. 6 new tests. |
-| (lets-go) | **Persistent Go stack live** (2026-05-01). All 11 daemons (storaged/catalogd/ingestd/queryd/embedd/vectord/pathwayd/observerd/matrixd/gateway/chatd) up as long-running processes on :3110+:3211-:3220, alongside the live Rust gateway on :3100 (no port conflict). First time the Go side runs as production-shape daemons rather than per-harness transient processes. Brought up via `scripts/cutover/start_go_stack.sh`. Gateway proxies `/v1/embed` correctly to embedd; all 5 chatd providers loaded. **First Go-side entry written to `data/_kb/audit_baselines.jsonl`** (entry #8, git_commit=`ee2a40c`, golangLAKEHOUSE SHA distinguishable from Rust's `ca7375ea`); the longitudinal log now mixes runtimes. |
+| (lets-go) | **Persistent Go stack live** (2026-05-01). All 11 daemons (storaged/catalogd/ingestd/queryd/embedd/vectord/pathwayd/observerd/matrixd/gateway/chatd) up as long-running processes on :3110+:3211-:3220 → later moved to :4110+:4211-:4219+:3220 for smoke isolation. First time the Go side runs as production-shape daemons rather than per-harness transient processes. Brought up via `scripts/cutover/start_go_stack.sh`. Gateway proxies `/v1/embed` correctly to embedd; all 5 chatd providers loaded. **First Go-side entry written to `data/_kb/audit_baselines.jsonl`** (entry #8, git_commit=`ee2a40c`, golangLAKEHOUSE SHA distinguishable from Rust's `ca7375ea`); the longitudinal log now mixes runtimes. |
+| (g5-slice) | **G5 cutover slice LIVE** (2026-05-01). First real Bun-frontend traffic reaching the Go substrate end-to-end. Bun mcp-server (`/home/profit/lakehouse/mcp-server/index.ts`) gains opt-in `/_go/*` pass-through to `$GO_LAKEHOUSE_URL` (set to `http://127.0.0.1:4110` via systemd drop-in). `/_go/v1/embed` returns nomic-embed-text-v2-moe vectors via Go embedd; `/_go/v1/matrix/search` returns 3/3 Forklift Operators against the persistent 200-worker corpus. Fully additive (no existing Bun tool modified) + fully reversible (unset env). `/api/*` (Rust gateway) path unchanged. See `reports/cutover/g5_first_slice_live.md`. |
 | (close-3) | **OPEN #3: distribution drift via PSI** — `internal/drift/drift.go`: `ComputeDistributionDrift` returns Population Stability Index + verdict tier (stable < 0.10, minor 0.10–0.25, major ≥ 0.25). Equal-width bucketing over combined min/max range, epsilon-clamping for empty buckets, per-bucket breakdown for drilldown. 7 new tests including identical-is-stable, hard-shift-is-major, moderate-detected-not-stable, empty-inputs-safe, all-identical-safe, bucket-counts-conserved, num-buckets-clamping. |
 | (close-4) | **OPEN #4: ops nice-to-haves** — (a) Real-time wall-clock for stress harness: per-phase elapsed time logged to stdout as it runs (`[stress] phase NAME starting (T+12.3s)` + `[stress] phase NAME done — 8.5s (T+20.8s)`); `Output.PhaseTimings` + `Output.TotalElapsedMs` written to JSON; (b) chatd fixture-mode S3 mock + (c) liberal-paraphrase calibration: not actioned — no fired trigger yet, would be speculative. Documented as deferred-until-need rather than ignored. |