feat(inference): QuaRot on-disk byte accounting + dry-run quant event

[ohdearquant]

What

QuaRot quantization: on-disk SafetensorsFile byte accounting, a GB size report, and a dry-run quant_done event with an honest-nil ratio.

Why

The Quantize surface reports how large the quantized artifact is and whether a dry run would shrink it. Byte accounting reads the on-disk SafetensorsFile rather than estimating. When a real ratio is not computable (dry run), the event omits it rather than fabricating a number (honest-nil).

Files

• crates/inference/src/quant/quarot/convert.rs
• crates/inference/src/quant/quarot/io.rs
• crates/inference/src/bin/quantize_quarot.rs

(+95/-15 across the three)

Verification

cargo build --release -p lattice-inference --bin quantize_quarot clean. Built green in the integrated-tree gate.

Bench

QuaRot conversion is not on the decode hot path and no Criterion harness covers it. make bench-compare's comparator errored assembling the delta (known two-worktree fragility; base benches ran clean) — bench-neutral by construction.

Series

Part of the PR #193 engine-slice (finest split). All engine code lands on main; the macOS app surfaces a subset (Models + Chat) for v0.0.1.

[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	0.5	2.7	PASS
In the year 2024, artificial intelligence	10/15	pos 9	0.4	0.9	PASS
`def fibonacci(n):

if n <= 1:
    return n
return` | 15/15 | none | 0.3 | 1.4 | 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