{ "artifact": "s08_o14_engine_rows", "sprint": "S08-O14", "claim": "The two rows this lane keeps under the S08 ownership split regenerate today from committed data: the engine-determinism 2x2 and the engine-counter sentence.", "method": "The determinism table is recomputed from the per-boot completion strings inside results/d3_determinism_2x2.json, with a planted and a scrubbed control run first; the engine-counter analysis is re-run by bench/run_s06_c1_analysis.py and compared value by value with the committed certificate, which is then restored.", "controls": { "planted_divergence": { "cell": "apc_off_inv0", "baseline": 0, "with_one_planted": 1, "control_fires": true }, "scrubbed_divergence": { "cell": "apc_on_inv0", "baseline": 6, "with_all_removed": 0, "control_fires": true } }, "controls_ok": true, "row1_engine_determinism": { "published": { "apc_on_inv0": 6, "apc_off_inv0": 0, "apc_on_inv1": 0, "apc_off_inv1": 0 }, "rederived": { "apc_on_inv0": 6, "apc_off_inv0": 0, "apc_on_inv1": 0, "apc_off_inv1": 0 }, "identical": true, "per_cell": { "apc_on_inv0": { "per_prompt": { "colours": { "boots": 6, "boots_first_differs_rest_agree": 6, "boots_all_identical": 0, "boots_rest_disagree": 0 }, "bridge": { "boots": 6, "boots_first_differs_rest_agree": 0, "boots_all_identical": 6, "boots_rest_disagree": 0 } }, "divergent_boot_prompts": 6, "prefix_caching": true, "batch_invariant": 0 }, "apc_off_inv0": { "per_prompt": { "colours": { "boots": 6, "boots_first_differs_rest_agree": 0, "boots_all_identical": 6, "boots_rest_disagree": 0 }, "bridge": { "boots": 6, "boots_first_differs_rest_agree": 0, "boots_all_identical": 6, "boots_rest_disagree": 0 } }, "divergent_boot_prompts": 0, "prefix_caching": false, "batch_invariant": 0 }, "apc_on_inv1": { "per_prompt": { "colours": { "boots": 6, "boots_first_differs_rest_agree": 0, "boots_all_identical": 6, "boots_rest_disagree": 0 }, "bridge": { "boots": 6, "boots_first_differs_rest_agree": 0, "boots_all_identical": 6, "boots_rest_disagree": 0 } }, "divergent_boot_prompts": 0, "prefix_caching": true, "batch_invariant": 1 }, "apc_off_inv1": { "per_prompt": { "colours": { "boots": 6, "boots_first_differs_rest_agree": 0, "boots_all_identical": 6, "boots_rest_disagree": 0 }, "bridge": { "boots": 6, "boots_first_differs_rest_agree": 0, "boots_all_identical": 6, "boots_rest_disagree": 0 } }, "divergent_boot_prompts": 0, "prefix_caching": false, "batch_invariant": 1 } }, "sentence": "On one model and one GPU class, the first request after a cold boot at temperature 0 diverges from the requests that follow it in 6 boot-prompts with prefix caching on and 0 with it off; the batch-invariant flag closes it (0 divergent).", "receipt": "results/d3_determinism_2x2.json" }, "row2_engine_counter": { "rerun_exit_code": 1, "committed": { "s46c_median_ratio": 0.949884, "s46c_p_value": 0.62503, "engine_hit_rate_apc_on_max": 0.038505905648019395, "engine_hits_total_apc_off_max": 0, "s47b_median_ratio": 1.024752, "s47b_significant": false, "primary_bar_passes": false, "aa_bar_passes": true }, "regenerated": { "s46c_median_ratio": 0.949884, "s46c_p_value": 0.62503, "engine_hit_rate_apc_on_max": 0.038505905648019395, "engine_hits_total_apc_off_max": 0, "s47b_median_ratio": 1.024752, "s47b_significant": false, "primary_bar_passes": false, "aa_bar_passes": true }, "identical": true, "differing_keys": [], "note": "the committed certificate is restored after the comparison; the re-run is the receipt, not a rewrite", "sentence": "With the trace-to-engine bridge gated in both directions, vLLM 0.28's own prefix-cache counters read 0.0385 against this lane's hash-only model at 0.0387, with zero hits when caching is off, in eight of eight replicates.", "receipt": "results/s06_c1_fixed_bridge_n8.json" }, "ownership": { "decided_by": "orchestrator S08 ownership table, row O14, accepting the two lanes' own split", "vllm_keeps": [ "engine determinism (this certificate, row 1)", "the engine-counter sentence (row 2)" ], "f5_keeps": [ "the theorems", "the cache-ceiling walls", "key-axis conformance", "the isolation tax", "the timing channel" ], "this_lane_cedes": "the isolation-tax claim; this lane's rows on it become receipts under f5's claim, and its own sentence retires to a cross-reference" }, "verdict": "BOTH ROWS REGENERATE: controls both fire; engine determinism recomputed from the per-boot completion strings gives {'apc_on_inv0': 6, 'apc_off_inv0': 0, 'apc_on_inv1': 0, 'apc_off_inv1': 0}, matching the published {'apc_on_inv0': 6, 'apc_off_inv0': 0, 'apc_on_inv1': 0, 'apc_off_inv1': 0}; the engine-counter analysis re-runs with every headline value identical (engine hit rate with caching on 0.038505905648019395, total hits with it off 0).", "wall_s": 1.1, "cost_usd": 0.0, "does_not_prove": [ "Anything beyond one model (Qwen2.5-1.5B-Instruct) and one GPU class for the determinism row: 6 boots per cell, two prompts, and no second model family.", "That the divergence is vLLM's fault rather than the stack beneath it: the cause is not isolated here, and the batch-invariant flag closing it is consistent with several causes.", "A knee uplift for the engine-counter row: the paired ratio at n=8 is not significant, and the row is the agreement between the engine's counters and the model, not an uplift.", "That either row regenerates the GPU run: both re-derive the analysis from committed raw data. The runs themselves are paid and are not repeated here." ], "generated_utc": "2026-09-04T19:58:43.987444+00:00", "git_rev": "fd54c78", "git_dirty": true, "run_id": "7f4c665b39134dd5", "host_kind": "Darwin-arm64", "provenance_schema": "gpu-cert-provenance/1" }