lfm3: add native Metal vision support above the text decoder

build.zig

@@ -93,6 +93,7 @@ pub fn build(b: *std.Build) void {
         @import("zig/build/step5_host.zig").steps(b, step5_mods.metal, step5_mods.engine, step5_mods.lanes);
     }
     @import("zig/build/h3_host.zig").tests(b, target, test_step);
+    @import("zig/build/lfm3_host.zig").steps(b, test_step);
     @import("zig/build/digest.zig").steps(b, test_step, draft_ids, build_options);
     @import("zig/build/flashnext_budget.zig").steps(b, test_step);
     @import("zig/build/flashnext_batch_host.zig").tests(b, test_step);

docs/receipts/lfm3/README.md

@@ -0,0 +1,188 @@
+# LFM3 Metal qualification receipts
+
+These receipts cover native LFM3-1.7B and LFM3-VL-2B from the official MLX exports.
+They distinguish implementation checks from the still-required maintainer model/performance gate.
+Checkpoint revisions and run instructions are in the [family recipe](../../recipes/lfm3-native.md).
+
+## Builds and hardware
+
+- Initial corrected native: `a8df9730ee637237545311a6753dd4bdcb13e860700d65a01a033ae818ee0d18`.
+- Optimized benchmark native: `5c8a04d4af599879797f4f5bed8e00ab7d9d70732e698bd2a1ec2a01ec762e09`.
+- Guarded row-pair build: `251079309919aa9b21ca8cc6a89c58fc3fc9a9baf800fa5ce6a6af313a5b5f65`.
+
+The guarded row-pair build additionally closes a diagnostic encoder when counter setup fails.
+That change does not alter the production projection or attention arithmetic. Its serving checks were rerun separately.
+
+Correctness runs used an M4 Pro with 48 GB RAM, macOS 26.5.1 and Zig 0.17.0.
+Controlled performance runs used an M5 Ultra with 256 GiB RAM and macOS 27.0 (26A428).
+A measured footprint on the M5 is not a smaller-RAM qualification.
+
+## Served and operator checks
+
+The optimized M4 binary passed all six greedy/seeded-sampling suites: 303 passed, zero failed or skipped.
+These cover drafted/plain, concurrent/solo, real cache reuse, edited prefixes, image order/content,
+corrupt input and cancellation/recovery. The guarded row-pair binary also passed 303/303 on the M5.
+
+Text4 and VL4 grammar runs on both hosts each passed 32 configurations, concurrent comparisons and five refusals.
+On each host, full-token capture verified 64/64 configuration groups, including hidden reasoning, across drafted/plain/concurrent requests.
+An additional 80 checks covered real required/named tools, typed arguments, streaming, tool-result history and image-conditioned calls.
+Grammar requires the matching optional library; these tests used an isolated bundle with library SHA-256
+`04133accdcecd01cd7dd4e8730855905850967ed8c6bd6d8a637258264ae7687`.
+
+The 4-bit text long suite passed 73/73, including chunk and 8,193-token seams.
+The row-pair LFM3-only contract run on the M4 reported:
+
+```text
+SUMMARY 50 kernels: 50 pass gates 1-4, 0 fail, 0 known findings; 13 controls: 13 red as planted, 0 missed; 0 limit problems; gates 19521 ms, limits 133 ms
+```
+
+The full earlier M5 runner reported 272/273 kernels passing, two known findings, all 298 controls red and zero limit problems.
+Its Qwen4 HC activation failure reproduces exactly in a separate build of pinned base `b30d5b9d3`.
+That is not a global pass or a final-source global-suite receipt.
+
+## Shared-stream attention follow-up
+
+`shared-attention.json` records the subsequent shared-dispatch source and binary identity.
+Full and sliding attention reuse the serial partial and merge arithmetic, with stream-local cache addresses and row maps.
+All 52 LFM3 kernels passed gates 1–4, all 14 controls were red as planted, and launch limits had zero problems.
+The real text4 default exactness suite passed 68/68, including unequal two/four-stream state and logits.
+All six sampled/cancellation serving suites on the M5 passed 303/303 with zero failures or skips.
+This follow-up is byte-preserving shared scheduling; it does not qualify tensor-unit prompt attention or a speed gate.
+
+## Numerical evidence
+
+`projection-fp64-bounds.json` covers 66 projection/layout cells and 60,954,624 outputs.
+The actual shared FP32 helper was captured before BF16 storage and compared with independently unpacked affine FP64 products.
+No raw FP32 or BF16-store error exceeded the existing derived bounds. Worst-column errors were retained.
+
+The row-pair optimization invokes the same shared helper and preserves its accumulation order.
+All 132 checkpoint comparisons at widths 1 and 64 produced 123,814,080 bytes identical to the old selector.
+A separate 8,193-token before/after check compared all 2,097,408,000 BF16 logit bytes exactly.
+Thus this optimization does not worsen any output-based precision metric on those comparisons.
+
+`fidelity-investigation.json` records the first actual primitive difference and its causal propagation.
+Official MLX 0.32.4 uses different effective affine reconstruction in its vector and matrix paths.
+The native engine consistently follows the FP32 affine equation rather than changing arithmetic with batch width.
+The first captured FP32 error was about 6.81e-9, inside the existing derived 5.52e-5 pre-store bound;
+it crossed a BF16 midpoint and propagated through recurrent history.
+
+`model-fp64-comparison.json` retains all 18 originally disjoint native/MLX positions, including repeated histories.
+With direct binary64-to-BF16 rounding, native belongs to the ideal model maximum set in nine cases, MLX in 16,
+both in eight and neither in one. This ideal FP64 model is a diagnostic; it does not execute the native FP32 reductions.
+No new tie tolerance or end-to-end acceptance threshold was applied. The primitive evidence does not replace that model gate.
+
+The oracle is reproducible with `tools/lfm3/fp64_reference.py`; its tests include all finite BF16 encodings,
+adjacent midpoints, double rounding, subnormals, overflow and six-bit cross-word unpacking.
+
+## Binned projection candidate
+
+`binned-projection.json` records the explicit candidate at `75478ed17`; ordinary model loading leaves it disabled.
+It preserves each input value while partitioning exponent ranges and exact code nibbles. M5 uses the shared
+`nax.h` tensor-unit fragments; M4 uses its fallback. Group affine sums use compensated FP32 pairs.
+The integer argument is limited to finite normal aligned products without overflow or underflow.
+It does not establish universal FP64 equivalence for extreme BF16 subnormals or arbitrary inputs.
+
+The actual native M5 tool produced **61,907,040/61,907,040** direct FP64-to-BF16 reference values across 132 captures:
+11 projection classes, all six checkpoints, and prompt/decode widths 64 and 1. All 66 first-row comparisons matched.
+The six small attention-gate cells use the unchanged row fallback and are included explicitly.
+No column had more FP64 error than either the retained original-native or MLX result.
+Those two comparator captures are from the M4, not a same-device M5 performance comparison.
+The file retains worst-column metrics, input/output hashes, artifact identities and the complete contract summaries.
+Both M4 and M5 passed all six operator variants, both planted controls and launch limits.
+These primitive results do not settle whole-model fidelity or served performance.
+
+To reconstruct the fixtures, save `fixture_tokens` as a little-endian uint32 NPY array and run the default
+`tf-lfm3-forward MODEL TOKENS.npy baseline.bf16 trace TRACE_DIR` for each named checkpoint.
+Concatenate the trace files ending in `_<input_stage>.bf16` in filename order to recreate each `input_file`;
+the first `2*k` bytes recreate its `one_row_file`. Verify the recorded input hash before comparing outputs.
+Run `tf-lfm3-project MODEL MODULE INPUT.bf16 ROWS OUTPUT.bf16 --binned` at widths 64 and 1.
+Save the receipt’s `cases` array as `manifest.json` beside the inputs for `tools/lfm3/projection_compare.py`.
+Use the frozen candidate commit for these artifact identities.
+
+`binned-row-twin.json` records the later opt-in row twin at `5a2bdea76`: all 132 captures retain
+123,814,080 bytes exactly against the earlier FP64-exact tiled captures. Both M4 and M5 pass six
+variants and two planted controls. The twin remains disabled for ordinary model loading because
+its serving performance has not passed; these operator results do not qualify a whole model.
+
+## Controlled performance
+
+`cold-prefill-ab.json` contains all 16 matched pairs / 32 fresh-server cold requests.
+It includes full output-token hashes, body hashes, client TTFT, engine prefill time and peak physical process footprint.
+Both sides used the same body, exact prompt counts, 16 output tokens, context 70,000, four configured lanes and zero cached tokens.
+The 2k and 8k cells have three alternating pairs each; 32k and 64k have one pair each.
+Only 4-bit performance was measured.
+
+Engine prefill seconds, before to after:
+
+- Text: 2k 1.239530 to 0.812959; 8k 5.307524 to 3.608895; 32k 27.314691 to 20.488389; 64k 73.402432 to 61.632933.
+- VL decoder, text requests: 2k 1.261845 to 0.815432; 8k 5.402433 to 3.617449; 32k 27.686643 to 20.536702; 64k 73.920498 to 59.646930.
+
+These are engine prefill times, not client TTFT. All 16 paired full output-token hashes matched.
+At 64k, physical footprint was 2,926,167,768 to 2,925,315,776 bytes for text and
+3,586,115,720 to 3,584,559,264 bytes for VL. Device/pinned allocator peaks were not collected.
+
+`decode-concurrency.json` records 256-token, three-repetition code/prose runs.
+All 60 concurrent-to-solo comparisons and all eight serial checks matched.
+Small decode-rate differences are descriptive; they are not a separately established speedup.
+
+Earlier standard-server comparisons still showed MLX-VLM faster, especially for long cold prefill.
+The faster arithmetic-changing matrix candidate failed the strict no-worse precision comparison and was excluded.
+The slower uniform-exponential candidate was also excluded. No unvalidated GQA experiment is enabled.
+
+## Paired FFN and CPU greedy follow-up
+
+`greedy-dual.json` records the subsequent immutable `b804c6ed` native build.
+The FFN gate/up projections share one dispatch while retaining each projection's shared helper and BF16 stores.
+A SIMD CPU greedy reduction preserves the first maximum, signed-zero ties and nonfinite rejection;
+masked and positive-temperature sampling keep the original path.
+All 58 LFM3 kernel checks passed, all 16 controls were red, and launch limits had zero problems.
+The real text4 exactness suite passed 68/68; six M5 sampled/cancellation serving suites passed 303/303.
+Actual projection pairs retained 247,628,160 bytes, and six complete teacher-forced logit arrays retained 394,752,000 bytes.
+
+Matched M5 old/new/new/old runs used three repetitions and 256 output tokens per request.
+All 240 concurrent full-token digests matched across the corresponding prompts and legs;
+240/240 concurrent-to-solo and 32/32 serial checks passed.
+Text code/prose single-stream rates changed from 309.27/322.59 to 317.39/332.83 tok/s;
+four-stream aggregate rates changed from 682.50/717.25 to 836.65/856.70 tok/s.
+VL decoder code/prose rates changed from 292.69/290.90 to 301.68/299.90 tok/s;
+four-stream rates changed from 656.00/658.15 to 813.40/810.10 tok/s.
+These are medians of the two run medians, with all raw three-repetition cells retained.
+This ABBA experiment measures only 4-bit performance and does not assert standard-server parity.
+
+## Reproduce
+
+Use the pinned Zig version and a complete local checkpoint. Developer references need NumPy; the MLX reference also needs MLX.
+
+```sh
+zig build native tf-lfm3-forward tf-lfm3-project tf-lfm3-profile tf-lfm3-exact tf-kernel-contract -Dcpu=apple_m1
+zig build test test-lfm3-host test-kernel-contract test-golden fuzz-cortheon -Dcpu=apple_m1
+python3 -m unittest discover -s tools/lfm3 -p 'test_*.py'
+./zig-out/bin/tf-kernel-contract --only LFM3
+./zig-out/bin/tf-lfm3-exact MODEL_DIR --long
+python3 tools/lfm3/serve_check.py --binary ./zig-out/native/bin/tensorfold-native --model-dir MODEL_DIR --sampled --cancel --output served.json
+python3 tools/lfm3/reference.py --model-dir MODEL_DIR --tokens TOKENS.npy --output mlx.bf16
+python3 tools/lfm3/fp64_reference.py --model-dir MODEL_DIR --tokens TOKENS.npy --output fp64.bf16 --weight-mode exact
+./zig-out/bin/tf-lfm3-forward MODEL_DIR TOKENS.npy native.bf16
+./zig-out/bin/tf-lfm3-profile MODEL_DIR TOKENS.npy profile.json
+```
+
+Repeat the served command for all six checkpoints. Run one model process per GPU, using the native lock and admission guards.
+`cold-prompts/` contains the exact request bodies and official rendered token arrays; SHA-256 hashes are in `cold-prompt-sha256.json`.
+The native server did not return its rendered arrays, so matching counts are not described as a captured native-token identity proof.
+To repeat cold HTTP measurements, start a fresh owned server with `--context 70000 --parallel 4 --prompt-cache-gib 0`,
+POST a saved body to `/v1/chat/completions`, and retain usage, full token hash and timings from the stream.
+The supplied bodies omit the optional model alias. Keep the exact bodies unchanged between compared builds.
+
+## All-width matched baseline
+
+`all-width-performance-baseline.json` records the shared-attention binary before the SIMD greedy and paired-FFN follow-ups.
+Both native and the standard server completed 72 retained single-stream requests, 360 retained concurrency requests and 48 cold requests in total.
+Every measured decode/concurrency reply has 256 tokens; each cold request has 16 output tokens and zero cached prompt tokens.
+All 180 native concurrent-to-solo and 24 serial comparisons matched. Exact public prompts, client hashes, token hashes and timings are retained.
+There is one cold sample per cell and three decode/concurrency repetitions. These baseline rates remain below the standard server; they are not a performance-gate pass.
+The native binary SHA is `d1656249bdb581b147faacbd3b3c557c00b6c45b710eeddce517a67178b6ba2b`.
+
+The public long-prompt wrapper is `tools/lfm3/bench_decode.py`; its prompts match the recorded JSON exactly.
+Use `python3 tools/lfm3/bench_decode.py decode URL MODEL --tokens 256 --reps 3 --temperatures 0 --output decode.json`.
+For concurrency use the `concurrent` mode with `--levels 1,4 --alone --serial` on native, or `--levels 1,4 --no-seed` on standard.
+Verify every reply length in the evidence; a shorter standard reply does not establish an equal-length rate.