A first dispatch of monolithic Task 2c was refused with a second scope
assessment that surfaced three architectural facts beyond what 2a/2b
had captured:
(d) attn_layer_norm_bwd_dx is a SIMPLIFIED element-wise approximation
(d_x = d_out * gamma / std), not the full LN Jacobian. Reusing
it in the GRN backward would propagate the approximation into
trunk gradients silently. Task 2c.1 must write a new full
Jacobian: (1/D) * rstd * (D * d_out_g - sum_d(d_out_g) -
normed * sum_d(d_out_g * normed)).
(e) IQN target-trunk migration is not a clean swap. iqn_compute_
target_h_s2 reproduces the legacy LeakyReLU trunk independently
in CUDA. Deleting it requires a target_encoder_forward_only
extraction on the target path (Task 4-style refactor on the
target side). Sub-task in itself.
(f) Three relu_mask removal sites have three different save-buffer
lifetimes (online trunk per-step, IQN-aux per-step in different
trainer, target-sync per-target-update). Three plumbing tasks,
not one.
Decomposition:
- 2c.1: grn_kernel.cu with full LN Jacobian backward + GLU + ELU +
residual-add. Module compiles standalone (additive, dead code).
- 2c.2: gpu_grn.rs Rust wrapper with 5 save-for-backward state
buffers per block (not 3 as the prior plan suggested).
- 2c.3+4: ATOMIC commit — compute_param_sizes 86→95 + fingerprint
rewrite + xavier init for 13 new tensors + all 98 padded_byte_
offset migrations + 3 relu_mask sites with different save-buffer
plumbing each + iqn target trunk delete + target_encoder_forward_
only + mag_concat RMS-match adaptive ISV.
- 2c.5: docs flip.
No code changes. Plan-doc only.
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