Forward wire (weight-side only — dispatch consumer lands in B.9):
direction Q-head's first FC weight tensor `w_b0fc` (param-table index
17) input dim grows by 1 to accept aux_softmax_diff. The (rows, cols)
shape table at the trainer-init Xavier site is updated in lock-step
with `compute_param_sizes()`. Output dim (adv_h) and the bias `b_b0fc`
are unchanged — bias is per-output, not per-input.
`layout_fingerprint_seed()` entry renamed `PARAM_W_B0FC` →
`PARAM_W_B0FC_AUX1`, forcing the FNV-1a hash to bump per Invariant 8
(old checkpoints fail-fast at load via `check_layout_fingerprint`
instead of silently aliasing onto the new architecture). Per
`feedback_no_legacy_aliases`, no `_DEPRECATED` shim — straight
in-place rename.
New weight column zero-initialised in trainer construction (mirrors
the OFI column zeroing for w_b2fc/w_b3fc): the model starts ignoring
the new input and learns to use it through gradient descent. Xavier-
init on this column would inject day-0 noise the trunk would have to
denoise — let the EGF gate decide when the aux signal is trustworthy.
Atomic-migration consumers (`feedback_no_partial_refactor`) updated:
- `gpu_dqn_trainer.rs` — Xavier (rows, cols) table at index 17 grows
to (adv_h, SH2+1); spectral-norm descriptor entry [4] for W_a1 grows
in_dim from sh2 to sh2+1; spec_v_a1 power-iteration vector grows
from sh2 to sh2+1 floats.
- `dqn/smoke_tests/gradient_budget.rs` — both `alloc_dueling`
fixtures' slot 8 grow `cfg.adv_h * cfg.shared_h2` →
`cfg.adv_h * (cfg.shared_h2 + 1)`.
- `docs/dqn-wire-up-audit.md` — new SP14 Layer B B.8 entry per
Invariant 7.
Note: forward GEMM dispatch still uses `K = shared_h2` until B.9 lands
the concat-then-SGEMM consumer (per plan §2358). Until then the new
column reads as ignored padding; this is safe because (a) it's zero-
initialised, (b) GPU-only smoke tests are skipped on this CPU CI, (c)
the fingerprint bump invalidates any pre-SP14 checkpoint that would
attempt to load.
Test: `layout_fingerprint_bumps_after_sp14_wire` (CPU-only, in
`sp14_oracle_tests.rs`) hashes the pre-B.8 seed verbatim with the
single difference `PARAM_W_B0FC` (vs post-B.8 `PARAM_W_B0FC_AUX1`)
and asserts `LAYOUT_FINGERPRINT_CURRENT` differs — any silent revert
of the rename trips this test. Mirrors the `fingerprint_bumped_from_
pre_b1_1a` pattern from `sp13_layer_b_oracle_tests.rs`.
Verified:
- `SQLX_OFFLINE=true cargo check -p ml` clean, 18 warnings (baseline)
- `cargo test -p ml --test sp14_oracle_tests` 2 passed, 6 ignored (GPU)
- `cargo test -p ml --test sp13_layer_b_oracle_tests
fingerprint_bumped_from_pre_b1_1a` still passes (sister test)
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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