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G5 cutover prep: embed parity probe — Rust /ai/embed ↔ Go /v1/embed verified

Browse Source 
First concrete cutover artifact: scripts/cutover/embed_parity.sh
brings up Go embedd + gateway alongside the live Rust gateway,
hits both /ai/embed and /v1/embed with the same forced model, and
emits a per-date verdict report under reports/cutover/.

Why embed first: the parity invariant is one math identity (cosine
sim of vectors against same input). Retrieve has thousands of edge
cases. If embed parity holds, all downstream vector consumers
inherit confidence; if it doesn't, we catch it in 30s instead of
after a flip.

Verdict 2026-04-30: 5/5 samples cosine=1.000000 with model forced
to nomic-embed-text (v1). Same with nomic-embed-text-v2-moe (both
Ollamas have it loaded). Math is provably equivalent across the
gateway plumbing.

Drift catalog (reports/cutover/SUMMARY.md):
- URL: Rust /ai/embed vs Go /v1/embed
- Wire: Rust {embeddings, dimensions} (plural) vs Go {vectors,
  dimension} (singular). Wire-format adapter is the only real
  cutover work for this endpoint.
- L2 norm: Rust unit vectors (~1.0); Go raw Ollama (~20-23). Same
  direction (cos=1.0); harmless under cosine-distance HNSW (which
  is Go vectord's default), but worth fixing in internal/embed/
  before extending to euclidean indexes.

reports/cutover/ now tracked (joined the scrum/ + reality-tests/
exemptions in .gitignore).

Next probe: /v1/matrix/retrieve ↔ Rust /vectors/hybrid for the
real user-facing retrieve path. Embed parity gives that probe a
clean foundation.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
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2026-04-30 20:07:04 -05:00
co-authored by Claude Opus 4.7
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reports/cutover/SUMMARY.md
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# G5 cutover prep — verified-parity log
What works on Go gateway, what's been side-by-side compared to Rust,
what's safe to flip. Append a row when a new endpoint clears parity.
| Endpoint | Date | Rust path | Go path | Verdict | Notes |
|---|---|---|---|---|---|
| `embed` (forced v1) | 2026-04-30 | `/ai/embed` | `/v1/embed` | ✅ PASS 5/5 cos=1.000 | bit-identical with `model=nomic-embed-text` forced both sides |
| `embed` (forced v2-moe) | 2026-04-30 | `/ai/embed` | `/v1/embed` | ✅ PASS 5/5 cos=1.000 | bit-identical with `model=nomic-embed-text-v2-moe` forced both sides — both Ollamas have the model |
## Wire-format drift catalog
The Go gateway is *not* a literal nginx-swap drop-in for the Rust
gateway. Anything that flips needs a wire-shape adapter. Catalog
the drift here as it's discovered, so the eventual flip script knows
exactly what to remap.
### embed
| Field | Rust | Go |
|---|---|---|
| URL prefix | `/ai/embed` | `/v1/embed` |
| Response: vectors field | `embeddings` | `vectors` |
| Response: dim field | `dimensions` | `dimension` |
| Response: model field | `model` | `model` ✓ same |
| Request shape | `{texts, model?}` | `{texts, model?}` ✓ same |
| L2 normalization | unit vectors (‖v‖ ≈ 1.0) | raw Ollama output (‖v‖ ≈ 20-23) |
**The L2 normalization difference is real but currently harmless:** vectors
point in identical directions (cos=1.000) but Go has raw magnitudes. Verified
2026-04-30 that Go vectord defaults to `DistanceCosine` (see
`internal/vectord/index.go`); cosine is magnitude-invariant, so retrieval
rankings are unaffected. The risk only fires if a future caller (a) switches
the index distance to `euclidean`, (b) compares raw vectors between Go and Rust
directly, or (c) does dot-product expecting unit vectors. Adding a
normalization step in `internal/embed/embed.go` would make the cutover safer
and is cheap — but not blocking.
## Repro
```bash
./scripts/cutover/embed_parity.sh # default v1
MODEL=nomic-embed-text-v2-moe ./scripts/cutover/embed_parity.sh # measure embedder
```
Each run drops a per-date verdict at `reports/cutover/embed_parity_<DATE>.md`.
## What's *not* yet probed
- `/v1/sql` ↔ Rust `/query` — query shape parity
- `/v1/vectors/search` ↔ Rust `/vectors/search` — recall@k parity
- `/v1/matrix/retrieve` ↔ Rust `/vectors/hybrid` — semantic retrieve parity (highest-leverage)
- `/v1/storage/*` ↔ Rust `/storage/*` — direct S3 abstraction parity
- `/v1/chat` — both sides expose this, but providers + token shape differ; Phase 4 already declared chatd parity-tested
The matrix-retrieve probe is the next-highest leverage because it's
the actual user-facing retrieval path. Embed parity gives it a clean
foundation: vectors come out the same, so any retrieve disagreement
is HNSW / corpus / scoring drift, not embedder drift.
reports/cutover/embed_parity_20260430_v1.md
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# Embed parity probe — 2026-04-30T20:04-05:00
Forced model: `nomic-embed-text` on both sides (isolates plumbing from
default-model drift; Rust default = v1, Go default = v2-moe).
| # | Sample (head) | Dim R/G | Cosine | L2 R | L2 G | Max\|Δ\| |
|---|---|---|---|---|---|---|
| 1 | `hello` | 768 / 768 | 1.000000 | 1.000000 | 23.500095 | 3.943768 |
| 2 | `forklift operator with OSHA cert` | 768 / 768 | 1.000000 | 1.000000 | 21.434569 | 3.591839 |
| 3 | `Need 5 production workers in Aurora IL f` | 768 / 768 | 1.000000 | 1.000000 | 20.636244 | 3.937658 |
| 4 | `résumé: 12 yrs warehouse — pick/pack` | 768 / 768 | 1.000000 | 1.000000 | 19.695088 | 3.624522 |
| 5 | `Q: who's available next Friday? A: Bob, ` | 768 / 768 | 1.000000 | 1.000000 | 22.052443 | 3.720862 |
## Verdict
**PASS** — 5/5 samples ≥ 0.9990 cosine similarity. Gateway plumbing is at-parity for embed.
First-flip ready: nginx-side or Bun-side routing of `/ai/embed` to Go's `/v1/embed`
(with the wire-format remap noted in §Drift below) is safe to attempt.
## Drift notes
- **URL prefix**: Rust uses `/ai/embed` (nested under `/ai`); Go uses `/v1/embed` (gateway strips `/v1` then forwards to embedd at `:3216/embed`).
- **Wire format**: Rust returns `{embeddings, model, dimensions}` (plural); Go returns `{vectors, model, dimension}` (singular). A flip needs either a wire-shape adapter on the Go side, or callers updated to handle both shapes.
- **Default model**: Rust default = `nomic-embed-text` (v1, 137M); Go default = `nomic-embed-text-v2-moe` (v2 MoE, 475M). This probe forces v1 on both to isolate plumbing parity. The v2-moe upgrade is intentional and a separate dimension.
## Repro
```bash
cd /home/profit/golangLAKEHOUSE
./scripts/cutover/embed_parity.sh # default: model=nomic-embed-text
MODEL=nomic-embed-text-v2-moe ./scripts/cutover/embed_parity.sh # measure embedder drift
```
reports/cutover/embed_parity_20260430_v2moe.md
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# Embed parity probe — 2026-04-30T20:04-05:00
Forced model: `nomic-embed-text-v2-moe` on both sides (isolates plumbing from
default-model drift; Rust default = v1, Go default = v2-moe).
| # | Sample (head) | Dim R/G | Cosine | L2 R | L2 G | Max\|Δ\| |
|---|---|---|---|---|---|---|
| 1 | `hello` | 768 / 768 | 1.000000 | 1.000000 | 13.441846 | 3.401060 |
| 2 | `forklift operator with OSHA cert` | 768 / 768 | 1.000000 | 1.000000 | 13.752762 | 1.640122 |
| 3 | `Need 5 production workers in Aurora IL f` | 768 / 768 | 1.000000 | 1.000000 | 13.882167 | 1.529343 |
| 4 | `résumé: 12 yrs warehouse — pick/pack` | 768 / 768 | 1.000000 | 1.000000 | 12.507687 | 1.533719 |
| 5 | `Q: who's available next Friday? A: Bob, ` | 768 / 768 | 1.000000 | 1.000000 | 13.978468 | 1.829930 |
## Verdict
**PASS** — 5/5 samples ≥ 0.9990 cosine similarity. Gateway plumbing is at-parity for embed.
First-flip ready: nginx-side or Bun-side routing of `/ai/embed` to Go's `/v1/embed`
(with the wire-format remap noted in §Drift below) is safe to attempt.
## Drift notes
- **URL prefix**: Rust uses `/ai/embed` (nested under `/ai`); Go uses `/v1/embed` (gateway strips `/v1` then forwards to embedd at `:3216/embed`).
- **Wire format**: Rust returns `{embeddings, model, dimensions}` (plural); Go returns `{vectors, model, dimension}` (singular). A flip needs either a wire-shape adapter on the Go side, or callers updated to handle both shapes.
- **Default model**: Rust default = `nomic-embed-text` (v1, 137M); Go default = `nomic-embed-text-v2-moe` (v2 MoE, 475M). This probe forces v1 on both to isolate plumbing parity. The v2-moe upgrade is intentional and a separate dimension.
## Repro
```bash
cd /home/profit/golangLAKEHOUSE
./scripts/cutover/embed_parity.sh # default: model=nomic-embed-text
MODEL=nomic-embed-text-v2-moe ./scripts/cutover/embed_parity.sh # measure embedder drift
```