parallel-execution

Parallel Execution Skill

Composite References

• references/error-handling.md: canonical R5 subagent-call resilience, common issue routing, escalation patterns, terminal non-interactive guardrails, and terminal lifecycle protocol.
• references/lean-dispatch-example.md: dispatch-prompt economy — lean before/after dispatch example for the canonical-source reference pattern.

Mode Declaration

Declare one mode before delegation: Execution Mode: parallel or Execution Mode: serial.

Record it in the progress-log header, step.metadata.execution_mode, the user-facing update, and any step-commit details tracked in the plan.

Requirement Contract (Mandatory)

Before delegation, define one shared Requirement Contract for the step:

Acceptance-criteria slice, explicit invariants and edge cases, and non-goals.

Both implementation and testing lanes must use the same contract.

Protocol

1. Choose mode using stability/risk criteria.
2. Create Requirement Contract before any lane starts.
3. Run lanes:
   • parallel: launch Code-Smith and Test-Writer against the same contract.
   • serial: run one lane first, then the second against the same contract.
4. Run triage via Test-Writer after outputs are available.
5. Classify failures as code defect, test defect, harness/env defect, or rc-divergence with evidence.
6. Route corrections bidirectionally until convergence:
   • code defect -> Code-Smith
   • test defect -> Test-Writer
   • harness/env defect -> responsible specialist or tooling path
   • rc-divergence -> Code-Smith fixes implementation to match the Requirement Contract; CC re-evaluates; if divergence remains, Test-Writer re-derives assertions from the Requirement Contract, not the corrected implementation.
7. Enforce convergence gate before advancing.
8. Run RC conformance check: CC evaluates the step's Requirement Contract AC items against delivered code after convergence. Divergences route as rc-divergence using step 6.

Convergence Gate (Mandatory)

Do not advance until Test-Writer explicitly confirms:

Green tests, valid assertions, and no brittle coupling.

After convergence, protocol step 8 verifies the Requirement Contract AC items before step advance.

Loop Budget

• Maximum 3 correction cycles per step.
• If exceeded, perform root-cause review and escalate with a recommended option.
• RC conformance correction gets 1 dedicated cycle outside the main 3-cycle budget. If still unresolved, escalate with the unresolved AC items and recommended options.

Anti-Test-Chasing Guardrail

Code-Smith must satisfy the Requirement Contract and architecture constraints, not merely optimize for current failing assertions.

If a property or test appears over-constrained or invalid, classify it as potential test defect and route it back for test review with evidence.

Post-Issue Checkpoint (Mandatory)

At issue/PR completion, record a short process checkpoint:

What slowed us down, what failed late, and what single guardrail should be added next?

Track this in the completion summary to improve future cycles. For subagent rate-limit handling, execution-time escalation, and terminal guardrails that pair with this execution contract, load references/error-handling.md.

Gotchas

Trigger	Gotcha	Fix
Lanes start with different requirements	Parallel work diverges and convergence turns into rework or churn	Define one shared Requirement Contract before any lane starts

Platform-specific invocation

This skill's methodology is tool-agnostic. Platform-specific routing lives alongside platforms/copilot.md and platforms/claude.md.