Portable Parallel Read

Shared invariant contract for the promoted portable read-only parallel-read route of the implement and manage skills. The loading skill's Parallel Adoption section supplies the consumer values: promoted consumer id and consumer_policy, safe parallel work, freeze list and join point, bootstrap exemptions, the literal parallel_execution.py preflight and validate-runtime commands, serial-parent ownership, resource-overlap wording, and the generic-write stop sentence. Those values and this contract apply together.

Portable Read-Only Route

Execution Route Selection must resolve to parallel-read before this section applies; auto does not select it. This consumer's runtime matrix and promotion remain mandatory. Serial parent work uses existing task authorization; exact-plan-digest approval applies when the promoted parallel-read route is selected. This route never bypasses consumer promotion, serial parent authority, or applicable write approval. Supplied denials or stale approvals remain invalid in every execution mode.

Required barrier

Apply shared host compatibility check before preparing any child work. Include read_host only from verified launcher-supported child controls. Missing or incompatible controls stop the selected parallel-read route before dispatch. A plan declaration is not effective-control proof, and post-run validation remains mandatory.

The frozen plan is the <run-directory>/execution-plan.json that the loading skill declares with its consumer_policy values.

For schema-3 runtime promotion, the frozen plan must include dispatch_choices keyed by every manifest node_id, each with exactly role_id, model, and reasoning_effort. The role must match the node. Use a nonempty string for an explicit spawn argument; use null to omit that argument and inherit the observed parent turn value. Runtime validation binds the plan to the actual spawn arguments and observed child controls; absent or ambiguous inherited parent controls fail closed.

It must also include write_policy: use parent_writes=planned with approval_requirement=exact-plan-digest when any parent mutation is planned, otherwise parent_writes=none with approval_requirement=not-required. When parallel-read is selected, a planned parent write requires <run-directory>/write-approval.json containing only exact plan SHA-256, response=approve, and source=explicit-input|user-prompt. Serial execution or an automatic serial fallback does not require a new digest receipt for already-authorized work.

Omit --approval when no parent writes are planned or effective execution is serial and no approval was supplied. Resolve host fallback before deciding whether the parallel route needs a receipt. A nonzero result stops route.

Run the same preflight again after the terminal join and before the first parent mutation. Any plan, approval, consumer, runtime, or join drift stops mutation and requires a new frozen plan plus exact approval.

Resource conflicts

Declare only validated resource locks such as git-index, cache:<path>, generated:<path>, and test-env:<name>.

Fallback

Unavailable or unsafe fan-out uses equal-gate serial-fallback from the same frozen plan with the same quality gates and retained evidence. Never label fallback as parallel or weaken checks because dispatch was unavailable.

Acceptance

This skill's shared runtime matrix and consumer promotion must remain complete before the selected parallel-read route starts. Acceptance must prove freeze, complete join, truthful execution label, resource compatibility, equal gates, and unchanged serial parent authority.

Stop rule

Stop without dispatch on missing promotion, mutable packs, ownership or resource overlap, sensitive or unproven controls, missing terminal evidence, or incomplete join.