GPU / research backlog — what’s left, and how to do it

The PRDs below can’t be finished-and-verified in a CPU sandbox: they need a GPU (training is the deliverable), special hardware, network installs, or are multi-week from-scratch model builds. The verifiable scaffolding ships (eval gates, tinygpt generate, recipes) — what remains is the run/implementation. This is the implementation outline for whoever picks them up on a GPU box.

Honesty note: I deliberately did not write thousands of lines of untested model internals (a from-scratch VLM/diffusion/TTS in one shot would be a hallucinated approximation). Each entry is an outline, not fake code.

Specialist training tier (eval gate + `generate` already ship)

The pipeline is built: sft --llrd → tinygpt generate → the eval gate. What’s left is the GPU run + (for some) a domain parse step.

A1 / B1 / B8 — recipes ship (scripts/recipes/a1-tool-caller.sh, b1-sql.sh, b8-indic.sh). Run on GPU with real SFT data; gates: eval-bfcl --lora (+3pp), eval-sql, eval-milu.
B2–B7 router — needs a router-predict step (run the trained classifier vs the FSM over BFCL queries → {method,predicted_tool,gold_tool}), then eval-router. The classifier/FSM exist (ToolRouterModel, PaceFastRouter); wire a predict loop, then the bake-off scorer is ready.
B5 / B35 — generate produces the raw response; add a thin parse (response → {defer_pred} for B5; → {found_issues:[]} for B35), then eval-escalate / eval-review score it.
B25-V2 — implement RelevanceHead (Linear d_model→2 on the final residual) + --loss relevance-bce in sft; the compress CLI swaps its lexical scorer for the head’s per-token scores. eval-scaledown already gates it.

Quantized-training tier

qlora — implement QLoraLinear/QDoraLinear: a frozen packed QuantizedLinear base (the inference load already ships, HFModel.swift) with LoRA on top, forward via quantized_matmul. Today sft --qlora fake-quants (LoftQ init on an fp16 base); the packed-base layer is the memory unlock.

Inference / port tier

vision-M4 — finish the Qwen3-VL forward in HFVLMLoader.load() (currently .notImplemented): weight materialization, mRoPE, image-token scatter, deepstack injection, then a parity test vs mlx_lm.
macos26-ANE / specialist-pace — both already shipped their engineering; the open items are measured runs / a closed product loop, not new code.

Hardware / network runs (no new code)

B16 M5 NA prefill bench — run scripts/bench_decode.py on M5, record the before/after in docs/research/mac_decode_baseline_m5pro.md.
C5 / B9 full — run bench_decode_thermal.py (30 min) / bench_energy.py under sudo (see setup_powermetrics_sudoers.sh); the harnesses ship.
E6-V2 — install-scalebench.sh then a wrapper over the official harness.
B17 round-trip — pip install sae_lens, load the exported SAE, assert parity.
B23/B26/B32/B33 — code ships; run the live GPU eval gates.

Tier 5 — multi-week from-scratch model builds

Each is a research project, not a session task. Outlines:

5.1 reasoning-on-22M (GRPO) — a GRPO/DAPO loop: rollout buffer, group-normalized advantage, KL-to-ref, on the file-ops env. Reuse the verified MLX GRPO primitives noted in the PRD.
5.2 testtime-compute-scaling — a scan-testtime harness over the existing bon (best-of-N) + a FLOPs counter → quality-vs-FLOPs curve. Smallest of the seven; mostly orchestration over shipped primitives.
5.3 vision-language-toy — LLaVA-style: ViT encoder + projector + LM, from scratch. New VLForward, TrainVL, EvalVQA.
5.4 diffusion-lm-micro — discrete masked-denoising 22M: DiffusionLM forward + masked-denoise train + iterative sample.
5.5 sparse-moe-kernels — blocked upstream on MLX scatter_add; dense MoE is the shipped fallback.
5.6 tts-toy — EnCodec tokens + autoregressive LM over codebook IDs.
5.7 explainer-video-model — storyboard DSL + renderer + a visual-planner specialist (depends on 5.3).