ci(lattice): harden merge gate — feature-matrix, bench-compile, cargo-deny, parity passthrough

[ohdearquant]

Why

cargo test/clippy --workspace only ever compiles default features. Feature-gated code (safetensors serialization, the inference-hook bridge, train-backward, metal kernels, the bench harnesses) is invisible to it. That is exactly how two real LoRA save/load bugs shipped this week in safetensors-gated code default CI never built (a91a7c05 on #193), and how the bench-internals build silently broke on main when quarot_rotation_seed was added to Qwen35Config without updating a bench initializer.

This PR shifts the merge gate from "a human approved it" to "green CI proves it compiles and matches HF" — and closes the feature-coverage hole so we cannot regress this class of bug again.

What

ci.yml

• Drop paths-ignore. A required status check that never runs leaves a PR stuck on "Expected — waiting for status to be reported" forever. CI now always runs on every PR to main; the cargo cache keeps doc-only re-runs cheap.
• feature-matrix (ubuntu + macos): compiles tune {safetensors, inference-hook, serde, train-backward}, inference {f16+train-backward, metal-gpu}, embed {local, metal-gpu}, fann --no-default-features. Metal steps gated to macOS.
• bench-compile (macOS / Apple Silicon): compiles the NEON bench harnesses (inference --features bench-internals, embed). x86 cfg's the NEON benches out, so the gate runs on aarch64 to be meaningful.
• cargo-deny (ubuntu): licenses/bans/sources required (deterministic), advisories informational (continue-on-error) so a fresh upstream RUSTSEC entry can't wedge merges.

e2e-parity.yml

• Remove the PR paths: filter so the workflow always reports a conclusion.
• Expensive macOS parity run is now gated behind a changes detector (git-diff of the engine surface).
• New always-running parity-gate job is the requirable context: passes when no engine change, mirrors the parity verdict when there is one, fails closed if change-detection itself errors.

deny.toml — permissive-only license allow-list, verified exhaustive via cargo metadata. No copyleft (LGPL appears only as an OR alternative, never forced). Sources locked to crates.io (verified zero git/alt-registry deps).

neon_forward.rs — add the missing quarot_rotation_seed: None to the bench-internals Qwen35Config initializer. This is a real breakage on main, invisible to default CI, that the new bench-compile gate is built to catch — included here so the gate is green on arrival.

Validation

Every gate command was run green locally before push:

Gate	Command	Result
feature-matrix	tune --features safetensors,inference-hook,serde --no-run	✅
feature-matrix	tune --features train-backward --no-run	✅
feature-matrix	inference --features f16,train-backward	✅
feature-matrix	inference --features metal-gpu	✅
feature-matrix	embed --features local / --features metal-gpu	✅
feature-matrix	fann --no-default-features	✅
bench-compile	inference --features bench-internals --no-run (post-fix)	✅
bench-compile	embed --no-run	✅
cargo-deny	check licenses bans sources → bans ok, licenses ok, sources ok	✅

After this lands, the repo ruleset will require: CI (×3), feature-matrix (×2), bench-compile, cargo-deny, parity-gate — and drop the human-review requirement in favour of green CI + auto-merge.

🤖 Generated with Claude Code

[github-actions]

E2E Parity Report

PASS: all 3 prompts match within first 3 tokens

Prompt	Agreement	First Diff	HF tok/s	Lattice tok/s	Verdict
The capital of France is	3/15	pos 3	0.2	1.3	PASS
In the year 2024, artificial intelligence	10/15	pos 9	0.3	1.5	PASS
`def fibonacci(n):

if n <= 1:
    return n
return` | 15/15 | none | 0.3 | 1.2 | PASS |

The capital of France is

• HF: Paris.
  The capital of France is Paris.
  The capital of France
• Lattice: Paris.
  A: Yes, the capital of France is Paris.

In the year 2024, artificial intelligence

• HF: (AI) has become a significant part of the global economy. It is
• Lattice: (AI) has become a significant part of our daily lives. From personal

def fibonacci(n): if n <= 1: return n return

• HF: fibonacci(n-1) + fibonacci(n-2)

print(fib

• Lattice: fibonacci(n-1) + fibonacci(n-2)

print(fib