golangLAKEHOUSE/docs/SPEC.md

SPEC: Lakehouse-Go Component Port Plan

Status: DRAFT — companion to PRD.md. Component-by-component port plan with library choices, effort estimates, and acceptance gates. Created: 2026-04-28 Owner: J

This spec answers: for each piece of the Rust Lakehouse, what Go library carries it, what the effort looks like, and what gate proves the port is real.

Effort scale (one engineer-week = ~40h focused work):

• S — 1–3 days
• M — 1 engineer-week
• L — 2–3 engineer-weeks
• XL — 1+ months
• HARD — open research, see PRD §Hard problems

---

§1. Component port table — Rust crates

Crate	Rust deps that mattered	Go target	Library	Effort	Risk
gateway	axum, tokio, tonic, tower	cmd/gateway	chi + stdlib net/http + google.golang.org/grpc	L	low — Go's strongest domain
catalogd	parquet-rs, arrow, sqlite	cmd/catalogd	arrow-go/v15, mattn/go-sqlite3	L	low
storaged	object_store, aws-sdk	cmd/storaged	aws-sdk-go-v2, minio-go for MinIO-specific paths	M	low
queryd	datafusion, arrow	cmd/queryd	marcboeker/go-duckdb (cgo)	HARD	high — see §3
ingestd	csv, json, lopdf, postgres	cmd/ingestd	stdlib encoding/csv, encoding/json, pdfcpu/pdfcpu, jackc/pgx/v5	L	low
vectord	hora, arrow, hnsw	cmd/vectord	coder/hnsw, arrow-go/v15	L	medium — re-validate HNSW recall
vectord-lance	lance	DROPPED	n/a	n/a	n/a — Parquet+HNSW only
journald	parquet, arrow	cmd/journald	arrow-go/v15	M	low
aibridge	reqwest	library	net/http + connection pool	S	low
validator	parquet, custom	library	arrow-go/v15 parquet reader	M	low — port the 24 unit tests as gates
truth	tomli, custom DSL	library	pelletier/go-toml/v2	M	low
proto	tonic-build	proto/ + protoc-gen-go	buf + protoc-gen-go-grpc	S	low
shared	serde, anyhow	library	stdlib encoding/json, errors	S	low
ui	dioxus, wasm	REPLACED	html/template + HTMX	L	medium — see §3
lance-bench	criterion	n/a — dropped with Lance	n/a	n/a	n/a

Total Rust crate port effort: ~12–18 engineer-weeks (3–4 months for one engineer; 6–8 weeks for two).

---

§2. Component port table — TypeScript surfaces

TS surface	Current location	Go target	Library	Effort	Risk
mcp-server/index.ts	Bun, :3700	cmd/mcp	mark3labs/mcp-go (Go MCP SDK)	L	medium — MCP semantics
mcp-server/observer.ts	Bun, :3800	cmd/observer	stdlib net/http, slog	M	low
mcp-server/tracing.ts	Bun, Langfuse client	library	go.opentelemetry.io/otel + Langfuse Go client (or hand-roll)	M	low — Langfuse Go OSS support varies
auditor/*.ts	TS, runs as systemd	cmd/auditor	stdlib + gitea API client	L	medium — auditor cross-lineage logic is intricate
tests/real-world/scrum_master_pipeline.ts	TS, ad-hoc	cmd/scrum	stdlib	L	medium — chunking + embed + ladder logic
tests/real-world/scrum_applier.ts	TS, ad-hoc	cmd/scrum-apply	stdlib + git CLI shell-out	M	medium
bot/propose.ts	TS	cmd/bot	stdlib	S	low
Search demo HTML/JS	static	static (no port)	n/a	n/a	n/a — copied as-is

Total TS port effort: ~6–10 engineer-weeks.

---

§3. Hard problem details

§3.1 — Query engine (DuckDB via cgo)

Library: marcboeker/go-duckdb — Go bindings via cgo.

API shape (replaces the DataFusion SessionContext pattern):

db, _ := sql.Open("duckdb", "")
defer db.Close()
db.Exec("CREATE VIEW workers AS SELECT * FROM read_parquet('s3://bucket/workers/*.parquet')")
rows, _ := db.Query("SELECT role, count(*) FROM workers WHERE state='IL' GROUP BY role")

Acceptance gates:

• G3.1.A — SELECT * FROM read_parquet('workers_500k.parquet') LIMIT 1 returns a row with the expected schema. Establishes Parquet read works.
• G3.1.B — Hybrid SQL+vector query (the POST /vectors/hybrid surface) returns same workers as the Rust path on the same input, ranked the same way modulo embedding precision.
• G3.1.C — Hot-cache merge-on-read: register a base table + a delta Parquet, query, observe both rows merged with the delta winning on conflict.

Fallback if cgo is rejected: run DuckDB as an external process (duckdb -json -c '...' shelled or HTTP via a thin Go wrapper). Adds operational surface; preserves SQL model.

§3.2 — HNSW index

Library: coder/hnsw — pure-Go HNSW, in-process. Supports add / delete / search / persist.

Open question: does coder/hnsw match the recall@10 we measured on the Rust hora path? Need a calibration test:

• Rebuild lakehouse_arch_v1 (the 1086-chunk arch corpus) in Go.
• Compare recall@10 on a fixed query set to the Rust baseline.
• Acceptance: ≤2% drop or we switch library / parameters.

Persistence format: TBD — coder/hnsw has its own snapshot format; ADR equivalent of ADR-008 (Parquet for embeddings + sidecar HNSW file) needs revisiting in Go to confirm the sidecar format we ship.

Acceptance gates:

• G3.2.A — Build HNSW from a Parquet of 100K vectors in <60s
• G3.2.B — Search 100K vectors at k=10 in <50ms p50
• G3.2.C — Recall@10 within 2% of Rust baseline on lakehouse_arch_v1

§3.3 — UI (HTMX)

Approach: server-rendered Go templates using html/template, HTMX for partial-page swaps, Alpine.js for client-side interactivity where needed. Single binary serves API + UI.

Acceptance gates:

• G3.3.A — Ask tab: type natural-language question, get answer from RAG endpoint, render in-page without full reload
• G3.3.B — Explore tab: paginated dataset list with hot-swap badge rendering
• G3.3.C — SQL tab: textarea → submit → tabular result rendered in-page
• G3.3.D — System tab: live tail of /storage/errors and /hnsw/trials via HTMX polling

Fallback if HTMX feels limiting: split repo golangLAKEHOUSE-ui with Vite + React, served as static files by Go gateway. Costs an extra repo + build chain.

§3.4 — Pathway memory port

Constraint: the Rust pathway_memory and TS implementations were byte-matching by ADR-021. The byte contract was verified by running both implementations on the same input tokens and asserting matching bucket indices.

Go port plan:

• Port the 32-bucket SHA256-keyed token hash exactly. Verify on a golden input that Go produces the same bucket vector as Rust.
• Port the JSON state file format verbatim — the existing 88 traces in data/_pathway_memory/state.json reload as-is into the Go implementation.
• Port the matrix-correctness layer (ADR-021's SemanticFlag, BugFingerprint, TypeHint) — these are pure value types, trivially portable.

Acceptance gates:

• G3.4.A — Load existing state.json, run replay on the same 11 prior successful pathways, all 11 succeed (matching the Rust 11/11 baseline).
• G3.4.B — Bucket vector for a fixed test input byte-matches the Rust output.

---

§4. Phase plan

Phase G0 — Skeleton (Week 1–3)

Scope: smallest end-to-end ingest + query path working in Go.

Component	Deliverable
cmd/gateway	HTTP on :3100, /health, /v1/chat proxy stub
cmd/catalogd	In-memory registry + Parquet manifest persistence
cmd/storaged	Single-bucket S3 / local FS, no error journal yet
cmd/ingestd	CSV → Parquet, schema inference, register-on-ingest
cmd/queryd	DuckDB-backed POST /sql endpoint

Acceptance: upload a CSV via POST /ingest, query it via POST /sql with a SELECT, get rows back. Single-bucket. No vector, no profile, no UI.

Phase G1 — Vector + RAG (Week 4–6)

Component	Deliverable
cmd/vectord	Embed-on-ingest (calls Python sidecar), HNSW build, POST /search
cmd/gateway	Add POST /rag (embed → search → retrieve → generate via aibridge)
cmd/aibridge	HTTP client to existing Python sidecar

Acceptance: ingest 15K resumes (the original Phase 7 fixture), ask "find me a forklift operator with OSHA-10 in IL", get ranked results with LLM-generated explanation grounded in the retrieved chunks.

Phase G2 — Federation + profiles (Week 7–8)

Component	Deliverable
cmd/storaged	Multi-bucket registry, rescue bucket, error journal at primary://_errors/
Profile system	Per-reader profile bound to bucket + vector index
Hot-swap	Atomic pointer swap for index generations

Acceptance: two profiles bound to two buckets, queries scoped correctly, hot-swap a vector index without query interruption, rollback works.

Phase G3 — Pathway memory + distillation (Week 9–11)

Component	Deliverable
cmd/vectord	Pathway memory module ported, 88 traces reloaded
Distillation pipeline	SFT export, contamination firewall, scorer
Audit baselines	audit_baselines.jsonl longitudinal signal port

Acceptance: replay 11 prior successful pathways, all 11 succeed. Re-run distillation acceptance on the frozen fixture set, 22/22 pass.

Phase G4 — TS surfaces → Go (Week 12–14)

Component	Deliverable
cmd/mcp	MCP server (replaces Bun) — /v1/chat, intelligence endpoints
cmd/observer	Autonomous iteration loop, op recording
cmd/auditor	PR audit pipeline (kimi/haiku/opus rotation)
cmd/scrum	Scrum master pipeline (replaces TS)

Acceptance: open a test PR, auditor cycles within 90s, emits verdict to data/_auditor/kimi_verdicts/, behavior matches Rust+TS era within tolerance.

Phase G5 — UI + demo parity (Week 15–16)

Component	Deliverable
cmd/gateway	Serves HTMX templates + static demo HTML
Demo at devop.live/lakehouse/	Parity with current Bun demo
Staffer console at /console	Parity

Acceptance: devop.live/lakehouse/ cuts over from Bun to Go gateway. Section ① / ② / ③ all render. Compact contract cards still expand with Project Index. Fill-probability bars still paint.

---

§5. Repo layout

golangLAKEHOUSE/
├── docs/
│   ├── PRD.md                    ← this PRD
│   ├── SPEC.md                   ← this spec
│   ├── DECISIONS.md              ← Go-era ADRs (start fresh, reference Rust ADRs by number)
│   └── ADR-XXX-*.md              ← per-ADR detail
├── cmd/
│   ├── gateway/                  ← main HTTP/gRPC ingress
│   ├── catalogd/
│   ├── storaged/
│   ├── queryd/
│   ├── ingestd/
│   ├── vectord/
│   ├── journald/
│   ├── mcp/
│   ├── observer/
│   ├── auditor/
│   └── scrum/
├── internal/                     ← shared packages, not exported
│   ├── aibridge/
│   ├── validator/
│   ├── truth/
│   ├── shared/
│   ├── proto/                    ← generated protobuf
│   └── pathway/
├── pkg/                          ← public Go packages (none initially)
├── web/                          ← UI (HTMX templates + static)
│   ├── templates/
│   └── static/
├── scripts/                      ← cold-start, smoke, distill scripts
├── tests/                        ← golden files, integration tests
├── go.mod
├── go.sum
└── README.md

Single Go module. All commands and internal packages live under golangLAKEHOUSE/. No nested modules unless a package needs an independent release cadence (none expected).

Build: go build ./cmd/... produces all binaries.

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§6. Migration data plan

What ports verbatim

• Parquet datasets at data/datasets/*.parquet — read by Go directly.
• Catalog manifests — Parquet, ports as data not code.
• Pathway memory state — JSON, ports if §3.4 byte-matching gate passes.

What rebuilds

• HNSW indexes — rebuild from Parquet embeddings on first Go startup.
• Auditor verdicts on PRs — old PRs won't be re-audited; lineage starts fresh on the new repo's PRs.

What's archived

• The Rust crates/ tree — preserved in the original repo at the cutover commit, tagged pre-go-rewrite-2026-04-28 for reference.
• TS surfaces (mcp-server/, auditor/, etc.) — preserved in the original repo at the same tag.
• Distillation v1.0.0 substrate (tag distillation-v1.0.0, e7636f2) — kept as the historical reference; Go re-implementation ports the LOGIC but not the bit-identical-reproducibility property unless an ADR re-establishes it.

What's discarded

• crates/vectord-lance/ (Lance backend, see PRD §Hard problems §2)
• crates/lance-bench/ (criterion benchmarks specific to Lance)

---

§7. Acceptance: when is the rewrite done?

The Go Lakehouse reaches feature parity when:

1. All 12 Rust PRD invariants hold (object-storage source of truth, catalog metadata authority, idempotent ingest, hot-swap atomicity, profiles, etc.).
2. The 16 distillation acceptance gates pass (re-run ./scripts/distill audit-full against the Go pipeline).
3. The 22/22 acceptance fixtures from tests/fixtures/distillation/ acceptance/ pass under the Go implementation.
4. The 145 unit tests of distillation v1.0.0 are ported and pass.
5. devop.live/lakehouse/ demo cuts over to Go gateway with no visible UI regressions.
6. Auditor emits Kimi/Haiku/Opus verdicts on a test PR, matching the cross-lineage rotation behavior.
7. The 88 pathway traces replay with 11/11 prior successes reproduced.

At that point the Rust repo enters maintenance-only mode (security fixes), and the Go repo becomes the live system.

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§8. Ratified — Phase G0 unblocked (2026-04-28, J)

#	Decision	Spec impact
1	DuckDB via cgo (marcboeker/go-duckdb)	§3.1 option A — proceed
2	HTMX + html/template + Alpine.js	§3.3 option A — proceed
3	git.agentview.dev/profit/golangLAKEHOUSE	repo location locked
4	Distillation rebuilt in Go (no bit-identical port)	§6 — port logic, not fixtures
5	Pathway memory starts empty; old traces noted	§3.4 G3.4.A is now "build initial state from scratch in Phase G3"; G3.4.B (byte-match) preserved as the porting correctness gate when the algorithm is reimplemented
6	Auditor longitudinal signal restarts	new audit_baselines.jsonl lineage starts on first Go-era PR

See docs/DECISIONS.md ADR-001 for full rationale and docs/RUST_PATHWAY_MEMORY_NOTE.md for where the legacy 88 traces live.

Phase G0 is now unblocked. Next step: bootstrap the Go module skeleton + push to Gitea, then begin §4 Phase G0 implementation.