Dispatch Work

dispatch_work — parallelize CP integration with coder+reviewer pairs

Use this only when there are multiple modules/tests to port at once. For one module, call /fold-cp:dtensor_modules + /fold-cp:test directly. Roles, the spawn-prompt template, the interface-reconciliation protocol, the review gates, and GPU partitioning are in coordination.md.

This skill assumes the agent-team tooling (Agent/TeamCreate/SendMessage/ Task*). If team_swarm:intercomm is installed, load it as the messaging protocol (verifiable artifact reports, lead health-checks). code_quality:write_test / run_test are the test-discipline references for reviewers.

Preconditions

• docs/current_code_structure.md (§4 module map, with reuse/adapt/new status) and docs/cp_infra.md (topology, world_size, GPU slots, launch recipe) exist.
• The fold-cp hard rules (RULES.md, injected at SessionStart) are in scope; every spawn prompt repeats them.

Step 1 — Build the work-list and the dependency graph

1. Collect every module/test marked adapt or new in §4 (plus any data-feature work still open from shard_data_feats).
2. Draw edges by data flow: producer → consumer where the producer's output feeds the consumer's input. Example chain: data features → atom encoder → trunk (OPM, triangle mult/attn, PWA, APB, transition, pairformer) → diffusion → confidence → losses. Each edge is a placement contract (producer output placement == consumer input placement).
3. Two items joined by an edge are coupled and must cross-review (Step 4).

Step 2 — Topologically sort into GPU-bounded waves

• Topo-sort the graph; items with no unmet dependency form the current wave.
• Bound each wave by GPU slots: slots = floor(free_GPUs / world_size) from cp_infra.md. Run at most slots CP test jobs concurrently; queue the rest.
• Independent leaves (e.g. several substrate primitives) can run fully parallel; a deep chain serializes by dependency, not by slot count.

Step 3 — Spawn a coder+reviewer pair per work item

For each item in the wave, spawn two agents (template in coordination.md):

• coder — owns the CP module and its test; implements per /fold-cp:dtensor_modules / /fold-cp:test, loads the module's row from module_map.md, the serial twin, and the relevant tech-guide §. Verifies the fwd+bwd decomposition on a 1×1 mesh (fp64) before the multi-rank parity run (/fold-cp:test Step 3) and runs the test green before handoff — this makes the GPU run pass first try and keeps the slot-bounded queue moving.
• reviewer — spawn as a read-only Explore agent (no Edit/Write): it reviews the coder's code and test against the gates in Step 5 and returns a verdict; it never writes (the coder owns all authoring + testing).

On a shared local (non-SLURM) box, give each pair a contiguous GPU chunk of world_size devices (CUDA_VISIBLE_DEVICES); never let two CP jobs share GPUs; probe occupancy and HOLD if busy (parallel tests otherwise overload the GPUs and stall). Under SLURM the scheduler handles per-job device visibility. Track each item as a Task (coder + reviewer subtasks).

Step 4 — Reconcile coupled up/down-stream contracts (the key step)

Before a coupled item is declared done, its coder and the neighbor's coder must cross-review the shared placement contract:

• the upstream coder states its module's output placements (and feature-dict outputs);
• the downstream coder states its module's expected input placements;
• they must be identical; if not, reconcile (one side adjusts, or insert an explicit redistribute) and update both modules and current_code_structure.md §3.

This catches the integration bug that unit tests miss: each module passes its own parity test but they disagree at the seam. The lead routes this exchange via SendMessage and does not advance the wave until every coupled seam is reconciled.

Step 5 — Review gates (reviewer enforces; lead verifies)

A work item is done only when its reviewer confirms all of:

1. Serial is ground truth — parity test compares against the serial fwd+bwd; no serial file was edited for distributed purposes (Rule 2).
2. No vacuous test — explicit random grad_output, sharding-active assert, replicated-identical assert, non-zero grads, fp64 default tolerances, >=1 adversarial case (Rule 14).
3. Hard rules — autograd.Function conventions, explicit from_local shape/stride, promote_types, backward budget matches forward, sorted collective keys, control-flow scalars broadcast (Rules 6–12).
4. Placement contract with neighbors reconciled (Step 4).
5. Tests pass under timeout, logged; pre-commit clean.

The lead verifies the reviewer's claim by inspecting the durable evidence (Rule 22) — the committed test is non-vacuous (Rule 14), the tee'd log shows measured-vs-tolerance for a run against the current tree, and the diff touches only the distributed tree (Rule 2) — re-running only if inspection leaves doubt, before marking the Task done.

Step 6 — Merge, verify landing, advance

• Squash-merge each approved item to the target branch (worktree isolation if coders edit in parallel — see isolation: "worktree"). After merge, re-run the item's parity test on the merged tree to confirm it still passes (landing verification — the merge changed the tree; Rule 22), then remove the item's worktree and shut down its coder + reviewer agents with an explicit shutdown_request (finished, no further task; completed background teammates do not auto-dismiss and TaskStop won't remove an idle one) — freeing their GPU chunk (destroy groups, kill orphaned ranks). See the coordination.md Shutdown & cleanup protocol.
• Update current_code_structure.md §4 status to done; advance to the next wave.
• When all waves complete, run the workflow-level parity test (end-to-end CP vs serial) as the final gate.

Alternative: stateless fan-out (prefer this for independent items)

If the items are independent (no coupling — e.g. porting a batch of unrelated substrate primitives), prefer a deterministic Workflow pipeline or foreground agents over a persistent background team. A Workflow pipeline (implement → parity-test → adversarial-verify per item) and foreground Agent calls (omit run_in_background) leave no lingering teammate — they return inline and never accumulate as idle rows in the agent view, whereas a messageable background team persists as idle teammates that must each be torn down with a shutdown_request. They're also lighter and minimise orchestrator round-trips (Rule 24). Reserve the persistent background team strictly for coupled seams that need mid-run lead↔coder messaging; use Workflow / foreground for embarrassingly-parallel ports.

Output contract

• Every scoped module/test implemented, parity-tested green, and reviewer-approved.
• Every coupled seam reconciled and recorded in current_code_structure.md §3/§4.
• A final end-to-end CP-vs-serial workflow test passing.
• A summary table: item → status → test-log path → reviewer verdict.