# Provider Execution Runtime Contract

## Contract metadata

- id: `iop.execution-runtime`
- boundary: inner
- status: active
- source evidence:
  - `packages/go/execution/types.go`
  - `packages/go/execution/registry.go`
  - `packages/go/execution/emitter.go`
  - `packages/go/execution/failure.go`
  - `apps/node/internal/node/runtime_bridge.go`
  - `apps/node/internal/node/command_handler.go`
  - `apps/node/internal/transport/session.go`
  - `apps/edge/internal/service/model_queue_release.go`
  - `apps/edge/internal/service/node_command.go`
  - `apps/edge/internal/openai/stream_gate_runtime.go`

## Scope

The execution package defines host-neutral provider primitives. It owns provider registration, lifecycle, execution events, typed failures, cancellation, token usage, and the three provider commands `capabilities`, `transport_status`, and `ollama_api`.

`session_id` is an opaque correlation value. It does not select, create, resume, or terminate a process. Repeated requests with the same value are independent executions. Cancellation targets a non-empty `run_id` only.

## Requirements

- Providers implement the narrow `Provider` interface and may expose optional lifecycle, command, or tunnel capabilities.
- Event emitters preserve order and publish exactly one terminal event.
- Registry lookup uses provider identity and returns typed failures for missing or unavailable providers.
- Callers must reject commands outside the closed provider-command allowlist before provider lookup.
- Token usage remains observation data attached to execution or tunnel results.
- `FailureCode` carries provider-neutral typed failures. The removed response-silence failure and its activity, probe, health-overlay, and provider-avoidance types are not runtime concepts.
- `RunRequest` and `ProviderTunnelRequest` do not carry a provider response-silence timeout. Silence produces no execution event, health mutation, or retry decision.
- Provider `complete`, `error`, and `cancelled` events, caller cancellation, the request hard deadline, and transport disconnect remain the explicit terminal inputs.
- A current provider or transport terminal releases its admission lease and request-owned resources exactly once. It does not start a health probe or select a replacement provider.
- `ProviderPoolDispatchRequest` contains no request-local provider-avoidance hint. Candidate selection continues to use the configured provider catalog, current connection ownership, capacity, priority, and queue policy.
- StreamGate consumes provider/transport terminals through the endpoint adapters. Output silence is not a filter input or recovery strategy.

## Prohibited ownership

The package must not own interactive shells, persistent processes, terminal emulation, working-directory mutation, resumable conversations, local quota probing, or arbitrary host command execution. It must not import application-internal packages or generated transport types.

## Verification

- `go test -count=1 ./packages/go/execution`
- `go test -race -count=1 ./packages/go/execution`
- `go vet ./packages/go/execution`