feat(runtime): compose createTangleProvider into createExecutor({ backend: 'provider' }) as a shipped example

[drewstone]

What is missing

createTangleProvider builds an AgentEnvironmentProvider over Tangle Sandbox, and createExecutor({ backend: 'provider' }) consumes an AgentEnvironmentProvider as executor data. The two halves are shipped and typed, but nothing composes them. No source file in this repository imports createTangleProvider, and no example, test, or export shows a caller how to hand a Tangle provider to createExecutor. A consumer that wants a Tangle box behind the provider seam has to derive the wiring from the type signatures alone, and cannot tell which of providerAsExecutor, ProviderSeam.registry, or a bare provider string is the intended entry point. Ship the composition: one exported helper, or one example plus one test that runs a profile in a Tangle box through backend: 'provider'.

Where it lives today

Nothing in the Discovery Lab uses this path. That is the finding: the Lab runs children through createExecutor({ backend: 'sandbox' }) with a hand-wrapped SandboxClient instead, which is issue (3) in this batch. The provider seam is the intended replacement for that wrapper and it has no worked example, so the Lab never adopted it.

Where it belongs

• agent-sdk packages/agent-provider-tangle/src/tangle-provider.ts:44 — export function createTangleProvider(.
• agent-runtime src/runtime/supervise/runtime.ts:460 — export interface ProviderSeam extends ProviderExecutorOptions.
• agent-runtime src/runtime/supervise/runtime.ts:4595 — the { backend: 'provider' } & ProviderSeam arm of the executor config union.
• agent-runtime src/runtime/environment-provider.ts:378 — export function providerAsExecutor(, marked @experimental.

Measured motive

0 of the source files under agent-runtime/src reference createTangleProvider. The only mention anywhere in the repository is a design note, docs/research/environment-provider-adapter-spec.md:397, which says "Then implement createTangleProvider(client) that maps:" — the spec that asked for the provider, never followed by a composed example.

Acceptance

The gap closes when a test in agent-runtime builds a provider with createTangleProvider, passes it to createExecutor({ backend: 'provider', provider }), runs one AgentProfile, and asserts the settled artifact — with providerAsExecutor no longer marked @experimental, or the helper exported under a stable name.

[drewstone]

Fixed by #1055 (d0172eb). examples/provider-executor/ ships the worked composition (README shows the exact createTangleProvider({ client }) -> createExecutor({ backend: 'provider', provider }) wiring, offline example runs both as a leaf factory and as SuperviseOptions.backend), tests/kernel/provider-executor-composition.test.ts runs one AgentProfile through the provider seam and asserts the settled artifact (6 tests, passing on main), and docs/canonical-api.md:160 routes callers to the seam. The test uses a contract-conforming fixture rather than importing createTangleProvider because Runtime deliberately holds no dependency on the provider package (canonical-api.md:160). providerAsExecutor stays @experimental on purpose: createExecutor (runtime.ts:5286) is untagged and STABILITY.md:18 makes that experimental by default, so promotion is a separate graduation issue for both symbols together (src/runtime/environment-provider.ts:494-498).