npu: count a gated q_proj's 2*QD rows, so check_q4nx_dir stops calling every attn_output_gate pack padded (Fixes #1285) - #1286

VERDICT: READY at 39bead7a — reproduced on the real 27B pack this box holds: the shipped checker calls a correct container broken (rc 1 on main), and this PR makes the same directory pass, while a non-gated container behaves identically to main.

Before/after, same directory, same command, only the tool differs (~/models/npu/bonsai2-27b-pb16i, whose config.json sets attn_output_gate; the pack the 313/410 ms rows in the leaderboard are about):

origin/main tool:  FAIL model.layers.47.self_attn.q_proj.weight: holds 7680 tiles, the model's dimensions
                        imply 3840 - columns padded 5120 -> 10240 (the 512-column grid) … (engine#1097)   [×6 layers]
                   chunk layout NOT verified                                                          rc 1
this PR's tool:    chunk layout verified: every quantized tensor's shape names a known chunk kind          rc 0

7680/3840 = 2, which is the whole point: a gated q_proj emits q and the output gate, so its rows are 2 * num_attention_heads * head_dim. The old code used QD and then explained a correct grid as padding — i.e. --strict failed on the real container, which is exactly the class of false red the check exists to prevent.

The negative side is unchanged: ~/models/npu/d3-synth-0.6b/ (no attn_output_gate) gives chunk layout verified … at both heads, so the new branch is inert for the containers that do not need it.

The self-test grew the arm and the anti-vacuity control for it: python3 tools/check_q4nx_dir.py --self-test rc 0 with … and a gated (attn_output_gate) q_proj's 2*QD rows are the model's own grid — and the arm refuses to pass silently, because it also asserts the same tensor shape does warn when attn_output_gate is absent ("the same q_proj is quiet without attn_output_gate, so the case proves nothing"). That is the right shape: a case that cannot fail would be worthless here.

Two details I checked because they are how this breaks later:

• the boolean is read the way the forward reads it — a JSON true or 1 (gate is True or gate == 1), matching q4nx_config_int, so a checkpoint that spells it as an integer is not silently treated as ungated;
• QG is carried in the same dims_from_config() dict the rest of the expectations use, so q_proj and o_proj stay consistent (o_proj remains (H, QD) — its input is q's pre-gate width, and the diff correctly leaves it alone).

Docs are in the PR (docs/npu.md names the rule and both issues); tool + self-test + doc in one change.

VERDICT: READY at acac5938 — main merges only; the reviewed content is byte-identical to the head I verdicted.

Checked rather than assumed: the PR's own added lines (own diff vs merge-base, which excludes everything main brought in) hash to 260cec477c38 at the head I reviewed and to the same value here, so no line of this PR's change moved — only its base did (the branch now sits on newer main).

Everything in my review at the previous head therefore still applies unchanged, including the numbers I re-derived there and the nits I named.

VERDICT: READY at 4f33529cceadac32758f1672d90d369ed663bf88. A small, correct fix, tested in both directions, and the 18-directory claim reproduces on a wider set.

Checked here (host only, no device)

• Scope: git diff --stat $(merge-base) 4f33529c is 2 files, +31/−5 (tools/check_q4nx_dir.py, docs/npu.md), as the body says. MERGEABLE.
• tools/check_q4nx_dir.py --self-test at the head: passes, rc 0.
• I tested the test: with qg = qd * 2 if mutated to qg = qd if, the self-test fails with attn_output_gate did not double q_proj's rows: {'QD': 2048, 'QG': 2048, …}, rc 1. The case also asserts that the same table still warns under ungated dims, so it cannot pass vacuously.
• The checker now agrees with the forward. npu/forward/src/q4nx_forward.cpp:757 reads attn_output_gate from config.json with q4nx_config_int, and q4nx_pack.h:187-192 documents q_proj as q|gate. Treating JSON true and 1 alike matches that. o_proj stays (H, QD), which is right: the gate is consumed before o_proj.
• Sweep, old (origin/main) vs new, --strict, over every model.q4nx directory under ~/models, ~/lb and ~/stage-c26. That is 31 directories, a superset of the body's 18:

No directory gains a warning or changes rc in the wrong direction.

• The new docs/npu.md sentence is in the same PR as the behaviour. copyright.py --check rc 0.

Notes, not blocking

• gate is True or gate == 1 treats any other nonzero int as ungated, while the forward treats any nonzero as gated (if (attn_gate_)). No config on the box uses another value, but bool(gate) (excluding strings) would match the forward exactly.
• #1275 edits the same file (the self-test tail and the success line). The two may conflict textually when the second one lands; they don't conflict logically.

Fixes #1285 is accurate: the false WARN / --strict rc 1 on gated containers is gone, measured.

VERDICT: READY at ecebe03510f05736e0c6adf4eaa30fd506417fab. Main merges only since my READY at 4f33529c: the PR diff's git patch-id --stable against its merge-base is identical (298bfe339e36) at both heads, and there are no non-merge commits of its own. Re-checked at this head: tools/check_q4nx_dir.py --self-test rc 0. The full review at 4f33529c stands.