test(inference): close Gemma 4 F32 attention evidence gaps (ST4A)

bench/baselines/gemma4-e2b-f32-attention-semantics-2026-07-12.json

@@ -1,8 +1,10 @@
 {
   "slice_id": "LARQL-INFERENCE-TRUST-001A-ST4",
+  "closeout_slice": "LARQL-INFERENCE-TRUST-001A-ST4A",
   "work_start_sha": "15864226bd3ffb70a2cdc35ca3e52dafe76692c7",
-  "pr_base_sha": "15864226bd3ffb70a2cdc35ca3e52dafe76692c7",
-  "head_sha": "pending PR head",
+  "head_sha": "2889157f29ea85d690db5d08290bad41154a346f",
+  "merge_commit": "b2584c0acf7691d9963dff6a557ec7bac58755d9",
+  "ci": "all 11 triggered workflows completed successfully",
   "intrinsic_window": 512,
   "layer_pattern": "SSSSG x7, final layer global (34)",
   "shared_kv_map": {
@@ -27,16 +29,70 @@
   "observed_attention_ranges": "match expected (t1-t9 PASS)",
   "range_mismatch_count": 0,
   "prefill_decode_comparison_count": 4,
-  "maximum_absolute_error": 1e-5,
+  "prefill_decode_method": "canonical kv_prefill_run vs kv_prefill_run+kv_decode_step_run (window-512 E2B-like fixture)",
+  "prefill_decode_abs_tolerance": 1e-5,
+  "prefill_decode_per_position": {
+    "511": {
+      "hidden_max_abs": 1.073e-6,
+      "hidden_max_rel": 1.023e-6,
+      "local_kv_tail_max_abs": 0.0,
+      "local_cache_len_route_a": 512,
+      "local_cache_len_route_b": 512,
+      "global_cache_len_route_a": 512,
+      "global_cache_len_route_b": 512,
+      "local_absolute_range": "0..=511",
+      "next_position_after_decode": 512
+    },
+    "512": {
+      "hidden_max_abs": 0.0,
+      "hidden_max_rel": 0.0,
+      "local_kv_tail_max_abs": 0.0,
+      "local_cache_len_route_a": 512,
+      "local_cache_len_route_b": 512,
+      "global_cache_len_route_a": 513,
+      "global_cache_len_route_b": 513,
+      "local_absolute_range": "1..=512",
+      "next_position_after_decode": 513
+    },
+    "513": {
+      "hidden_max_abs": 0.0,
+      "hidden_max_rel": 0.0,
+      "local_kv_tail_max_abs": 0.0,
+      "local_cache_len_route_a": 512,
+      "local_cache_len_route_b": 512,
+      "global_cache_len_route_a": 514,
+      "global_cache_len_route_b": 514,
+      "local_absolute_range": "2..=513",
+      "next_position_after_decode": 514
+    },
+    "1024": {
+      "hidden_max_abs": 0.0,
+      "hidden_max_rel": 0.0,
+      "local_kv_tail_max_abs": 0.0,
+      "local_cache_len_route_a": 512,
+      "local_cache_len_route_b": 512,
+      "global_cache_len_route_a": 1025,
+      "global_cache_len_route_b": 1025,
+      "local_absolute_range": "513..=1024",
+      "next_position_after_decode": 1025
+    }
+  },
+  "prefill_decode_maximum_absolute_error": 1.073e-6,
   "cache_length_mismatch_count": 0,
   "absolute_position_mismatch_count": 0,
   "shared_consumer_count": 2,
   "independent_shared_cache_allocation_count": 0,
   "shared_consumer_kv_append_count": 0,
+  "source_append_deltas_per_decode_token": {
+    "local_source": "+1 (clipped to intrinsic window)",
+    "global_source": "+1 (unbounded)",
+    "local_consumer": 0,
+    "global_consumer": 0
+  },
   "poison_weight_test_result": "PASS",
   "incompatible_geometry_result": "fails loudly (panic)",
-  "qwen_regression_result": "N/A (no Qwen CPU F32 fixture; conventional full-attention retained)",
-  "q4k_regression_result": "PASS (regression-only, not claiming ST4 coverage)",
+  "qwen_regression_result": "PASS (Qwen2 full attention: intrinsic_window=None, 600-token prefill retains full prefix, decode grows cache +1, no shared-KV routing, old-key sensitivity abs=3.679e-4 rel=1.334e-2 at position 600 vs position 0 outside a 512-window)",
+  "q4k_regression_result": "PASS (regression-only, NOT part of the ST4/ST4A GREEN claim)",
   "semantic_official_model_run": false,
   "decision": "GREEN",
   "excluded_q4k_paths": [
@@ -47,9 +103,19 @@
     "coarse_prefill",
     "coarse_decode_step"
   ],
+  "st4a": {
+    "work_start_sha": "eb40807ef0c392cd34456406b936692c13741716",
+    "tested_implementation_sha": "97ff07bb28e36420e07a015af0e4b32ccc736ef0",
+    "new_fixtures": [
+      "make_synthetic_e2b_like_weights_random_window512",
+      "make_qwen2_test_weights"
+    ],
+    "boundary_positions_tested": [511, 512, 513, 1024],
+    "decision": "GREEN"
+  },
   "synthetic_tests": {
-    "st4_attention_semantics": 18,
-    "st4_shared_kv": 17,
+    "st4_attention_semantics": 26,
+    "st4_shared_kv": 28,
     "st4_e2b_mapping": 5
   }
 }

bench/baselines/gemma4-e2b-f32-attention-semantics-2026-07-12.md

@@ -1,6 +1,6 @@
-# Gemma 4 E2B F32 CPU Attention Semantics (ST4)
+# Gemma 4 E2B F32 CPU Attention Semantics (ST4 + ST4A closeout)
 
-Slice: `LARQL-INFERENCE-TRUST-001A-ST4`
+Slice: `LARQL-INFERENCE-TRUST-001A-ST4` (closed by `…-ST4A`)
 
 ## Decision
 
@@ -12,11 +12,22 @@ A GREEN result means only that the F32 CPU path now implements the
 required local/global attention ranges, absolute positions, and shared-KV
 routing needed for the next external semantic comparison.
 
-## Revisions
+ST4A closed the remaining evidence gaps without reopening or expanding the
+ST4 implementation scope: it added the missing canonical-loop prefill/decode
+equivalence at the 512-window boundaries (511/512/513/1024), an explicit
+Qwen2 full-attention regression, and a source append-count proof, and
+corrected this report's ST4 metadata.
 
-- Work-start SHA: `15864226bd3ffb70a2cdc35ca3e52dafe76692c7`
-- PR base SHA: `15864226bd3ffb70a2cdc35ca3e52dafe76692c7`
-- Head SHA: _filled at PR head_
+## Revisions (corrected by ST4A)
+
+- ST4 work-start SHA: `15864226bd3ffb70a2cdc35ca3e52dafe76692c7`
+- ST4 head SHA: `2889157f29ea85d690db5d08290bad41154a346f`
+- ST4 merge commit (squash into main): `b2584c0acf7691d9963dff6a557ec7bac58755d9`
+- ST4 CI: all 11 triggered workflows completed successfully.
+- ST4A work-start SHA: `eb40807ef0c392cd34456406b936692c13741716`
+- ST4A tested implementation commit SHA: `97ff07bb28e36420e07a015af0e4b32ccc736ef0`
+  (the ST4A tests commit immediately before this evidence commit; checks out
+  to the ST4 implementation plus the ST4A tests that verify it).
 
 ## What changed (F32-only)
 
@@ -45,7 +56,9 @@ routing needed for the next external semantic comparison.
 
 These pass `effective_window = None` (full causal) and do not route
 shared-KV. The intrinsic Gemma 4 local/global and shared-KV parity must be
-verified separately before they become semantic-oracle candidates.
+verified separately before they become semantic-oracle candidates. **Q4_K
+remains excluded from the ST4/ST4A GREEN claim**; it may run as a
+regression only.
 
 ## E2B local/global pattern + shared-KV map
 
@@ -57,7 +70,7 @@ verified separately before they become semantic-oracle candidates.
 - every shared layer points to a source of the same attention type
 - complete shared-KV map result: PASS (5 mapping tests)
 
-## Synthetic test results (ST4 §19)
+## Synthetic test results (ST4 §19, refreshed by ST4A)
 
 | Group | Count | Result |
 |-------|-------|--------|
@@ -69,39 +82,141 @@ verified separately before they become semantic-oracle candidates.
 | Regressions (t43, t44) | 2 | PASS |
 | E2B 35-layer mapping | 5 | PASS |
 
+Totals (current): `st4_attention_semantics` 26, `st4_shared_kv` 28
+(includes 11 ST4A closeout tests), `test_architectures` st4_* 5.
+
 - range mismatch count: 0
 - cache-length mismatch count: 0
 - absolute-position mismatch count: 0
-- prefill/decode comparison count: 4 boundary positions
-- maximum absolute error: ≤ 1e-5 (GQA primitive parity; bit-exact where
-  operation ordering is identical)
+- prefill/decode comparison: real canonical-loop numerical comparison at 4
+  boundary positions (see ST4A closeout below for measured values).
 - shared consumers tested: 2 (sliding L2, global L3 on the 4-layer fixture)
 - independent shared-cache allocation count: 0
 - shared consumer K/V append count: 0
 - poison-weight test result: PASS (consumer K/V poison has no effect;
   source K/V mutation changes output)
 - incompatible-geometry result: fails loudly (panic)
-- Qwen regression result: N/A (no Qwen fixture in the CPU F32 unit suite;
-  conventional full-attention retained via `intrinsic_window = None`)
-- Q4_K regression result: PASS (regression-only, not claiming ST4 coverage)
+- Qwen2 regression result: **PASS** (full-attention regression; see ST4A §2)
+- Q4_K regression result: PASS (regression-only, NOT part of the GREEN claim)
 - semantic official-model run = false
 
 ## Verification commands and totals
 
 ```
 cargo fmt --all -- --check                              # clean
-cargo test -p larql-models --lib                        # 425 passed
-cargo test -p larql-compute --lib                       # 756 passed
-cargo test -p larql-inference --lib                     # 1290 passed
-cargo test -p larql-kv --lib                            # 765 passed
-cargo test -p larql-vindex --lib                        # 1154 passed
-cargo test -p larql-cli --bins                          # 243 passed
-cargo test -p larql-compute --test st4_attention_semantics   # 18 passed
-cargo test -p larql-kv --test st4_shared_kv                  # 17 passed
-cargo test -p larql-models --test test_architectures (st4_*) # 5 passed
-cargo clippy -p larql-{models,compute,inference,kv,vindex,cli} --all-targets -- -D warnings  # clean
-cargo test -p larql-compute q4k / larql-inference q4k / larql-vindex q4k  # green (regression)
-cargo build -p larql-cli --release                      # passed
+cargo test -p larql-compute --test st4_attention_semantics   # 26 passed
+cargo test -p larql-kv --test st4_shared_kv                  # 28 passed
+cargo test -p larql-models --test test_architectures         # 90 passed (st4_* = 5)
+cargo test -p larql-models                                   # green
+cargo test -p larql-compute                                  # green
+cargo test -p larql-inference                                # green
+cargo test -p larql-kv                                       # green
+cargo clippy -p larql-{models,compute,inference,kv} --all-targets -- -D warnings  # clean
+```
+
+CI status (ST4 PR #60): all 11 triggered workflows completed successfully.
+
+---
+
+## ST4A closeout
+
+- work-start SHA: `eb40807ef0c392cd34456406b936692c13741716`
+- tested implementation commit SHA: `97ff07bb28e36420e07a015af0e4b32ccc736ef0`
+  (the ST4A tests commit immediately before this evidence commit; ST4A is
+  tests + evidence only — no attention implementation change).
+- new fixtures: `make_synthetic_e2b_like_weights_random_window512`
+  (4-layer E2B-like Gemma 4 with a 512-token intrinsic window) and
+  `make_qwen2_test_weights` (Qwen2 full-attention with Q/K/V biases).
+
+### Boundary positions tested
+
+511, 512, 513, 1024 — the 512-window boundary and the first clipped
+position, plus a far-clipped position.
+
+### Per-position canonical prefill/decode equivalence
+
+Route A = one-shot `kv_prefill_run` of tokens `0..=target`; Route B =
+`kv_prefill_run` of `0..target` then one `kv_decode_step_run` at the true
+absolute position. Absolute tolerance `1e-5`.
+
+| target | hidden max abs | hidden max rel | local K/V tail max abs | local len (A=B) | global len (A=B) | abs position (B) |
+|--------|---------------:|---------------:|-----------------------:|----------------:|-----------------:|-----------------:|
+| 511    | 1.073e-6       | 1.023e-6       | 0                      | 512             | 512              | 512              |
+| 512    | 0              | 0              | 0                      | 512             | 513              | 513              |
+| 513    | 0              | 0              | 0                      | 512             | 514              | 514              |
+| 1024   | 0              | 0              | 0                      | 512             | 1025             | 1025             |
+
+The largest hidden-state difference across all four positions is `1.073e-6`
+(target 511); positions 512/513/1024 are bit-exact between routes. The
+local source K/V tail is bit-exact (`0`) at every position, confirming
+both routes hold the same absolute RoPE positions after clipping.
+
+### Local cache evidence
+
+Every target yields a 512-row local source cache in both routes, matching
+the intrinsic window:
+
+```
+target 511  → 512 rows, absolute range 0..=511
+target 512  → 512 rows, absolute range 1..=512
+target 513  → 512 rows, absolute range 2..=513
+target 1024 → 512 rows, absolute range 513..=1024
 ```
 
-CI status: pending PR creation (all local checks green).
+### Global cache evidence
+
+The global (full-attention) source retains the entire prefix — `target+1`
+rows in both routes (512 / 513 / 514 / 1025).
+
+### Absolute-position evidence
+
+After the decode, `cache.next_position == target+1` (512 / 513 / 514 /
+1025), not the clipped 512 cache length. The bit-exact local K/V tail
+between Route A (natural positions) and Route B (`next_position`-derived
+RoPE) is the direct proof that the absolute RoPE position is the true
+target position.
+
+### Source append deltas (per decode token, 4-layer E2B-style fixture)
+
+```
+local source   → +1 row (clipped to its intrinsic window)
+global source  → +1 row (unbounded)
+local consumer → 0 rows
+global consumer → 0 rows
+```
+
+Invariant holds on every one of 6 consecutive decode steps.
+
+### Shared consumer append count
+
+0 — shared consumer layers hold no independent cache before, during, or
+after any decode step (verified by `cache.layers[c].is_none()`).
+
+### Qwen2 regression
+
+PASS. On a real Qwen2 architecture (`family == "qwen2"`, Q/K/V biases):
+
+- `intrinsic_attention_window == None` on every layer;
+- prefill of 600 tokens retains the full 600-row causal prefix (no
+  clipping) on every layer;
+- decode grows the cache by exactly one row per token (5 steps);
+- no layer activates Gemma 4 shared-KV routing (`kv_shared_source_layer == None`);
+- old-key sensitivity: zeroing the K/V of position 0 changes the
+  position-600 decode output by `abs = 3.679e-4`, `rel = 1.334e-2`. Position
+  0 lies outside a 512-token local window for position 600 (window =
+  89..600), so this change proves Qwen2 attends to the early key under full
+  attention.
+
+### Q4_K scope statement
+
+Excluded from the ST4/ST4A GREEN claim. Q4_K paths run `effective_window
+= None` and do not route shared-KV; they pass as regressions only and
+require separate semantic verification before becoming oracle candidates.
+
+### Decision
+
+**GREEN.** All 15 ST4A decision-gate criteria pass; the canonical
+prefill/decode outputs are numerically equivalent (≤ `1.073e-6` abs) at
+511/512/513/1024, local/global cache lengths and absolute positions are
+correct, Qwen2 full attention is regressed, source append counts are
+exact, and Q4_K remains outside the claim.

crates/larql-inference/src/test_utils.rs

@@ -908,8 +908,9 @@ pub fn make_test_gemma4_moe_weights() -> ModelWeights {
 // so existing `crate::test_utils::*` callers (forward/ple.rs tests) and
 // downstream test crates keep working.
 pub use larql_models::test_fixtures::{
-    make_synthetic_e2b_like_weights, make_synthetic_e2b_like_weights_random,
-    synthetic_e2b_like_arch_json,
+    make_qwen2_test_weights, make_synthetic_e2b_like_weights,
+    make_synthetic_e2b_like_weights_random, make_synthetic_e2b_like_weights_random_window512,
+    synthetic_e2b_like_arch_json, synthetic_e2b_like_arch_json_window512,
 };
 /// Bundled fixture for Q4_K decode-path tests. Mirrors `TestFixtures`.
 pub struct Q4KTestFixtures {