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>

reports/cutover/SUMMARY.md

@@ -12,6 +12,7 @@ what's safe to flip. Append a row when a new endpoint clears parity.
 | `audit-FULL` (phases 0/1/2/3/4/5/7 — observer mode) | 2026-05-01 | `scripts/distillation/audit_full.ts` | `cmd/audit_full` + `internal/distillation` `RunAuditFull` | ✅ PASS 12/12 | Skips reduced from 4 → 1: phase 1 invokes `go test`, phases 2/5/7 read existing artifacts as observers (no live materializer/replay invocation). Only phase 6 (TS-only acceptance harness) remains skipped. `p2_evidence_rows=1055` matches Rust `summary.json` `collect.records_out=1055` byte-equal. Updated `audit_full_go_vs_rust.md`. |
 | `audit_baselines.jsonl` write side | 2026-05-01 | `data/_kb/audit_baselines.jsonl` (Rust-emitted, 7 entries) | Go-emitted entry #8 via `cmd/audit_full -append-baseline` | ✅ Mixed-runtime log | First Go-side entry written to the shared longitudinal log: `git_commit=ee2a40c5...` (golangLAKEHOUSE SHA, distinguishable from prior Rust SHAs like `ca7375ea`). All 10 metric fields match Rust shape exactly — drift comparator fires correctly across the runtime boundary. |
 | Full Go stack (persistent) | 2026-05-01 | per-binary on :31xx | 11 daemons (storaged/catalogd/ingestd/queryd/embedd/vectord/pathwayd/observerd/matrixd/gateway/chatd) | ✅ All 11 healthy | First time the Go stack runs as long-running daemons rather than per-harness transient processes. Brought up via `scripts/cutover/start_go_stack.sh`; gateway proxies `/v1/embed` correctly through to embedd; all 5 chatd providers loaded. Live alongside the Rust gateway on :3100 (no port conflict). |
+| **G5 cutover slice live** | 2026-05-01 | (none — pure cutover) | Bun `/_go/*` → Go gateway `:4110` | ✅ End-to-end | First real Bun-frontend traffic to Go substrate. Rust legacy `mcp-server/index.ts` gains opt-in `/_go/*` pass-through driven by `GO_LAKEHOUSE_URL` env (systemd drop-in at `/etc/systemd/system/lakehouse-agent.service.d/go-cutover.conf`). `/_go/v1/embed` returns nomic-embed-text-v2-moe vectors; `/_go/v1/matrix/search` returns 3/3 Forklift Operators against persistent stack's 200-worker corpus. Reversible (unset env or revert systemd unit). See `g5_first_slice_live.md`. |
 
 ## Wire-format drift catalog