Resume through durable effects performed inside generated XMD

[taras]

Story

As a workflow author, I want a retained workflow to resume through durable effects performed inside an admitted generated-XMD fragment, so completed observations and mutations are restored exactly once and later authored effects continue in order.

Context and ownership

This is a regression against #369's settled continuation contract, not a new admission policy, product decision, or durable-stream schema.

The defect was confirmed while implementing #301 slice 2 on draft PR #181:

• exact reproducer head: 9ef6edcf205f57ba08cc84ba7a009919ed403957;
• base/current main when frozen: f230e8fd59df293fb9b1677ef4a7466900be4a99;
• a generated fragment with a durable effect runs on start;
• a later suspension is retained;
• resume diverges before the nested generated effect is re-offered;
• removing <Evaluate>, or keeping a generated fragment with no durable effect, allows resume to complete.

Leave #369 closed as the historical delivery and link it to this correction.

PR #181 remains paused. This issue and its implementation PR own the production correction; #181 will later rebase and convert AC4 from a blocker assertion into a successful continuation regression with zero repeated evidence-provider reads.

Settled ownership and replay contract

Generated admission and every nested generated effect belong to the same owning durable document expansion. They must be offered in authored order:

generated_xmd
nested generated effect 1
nested generated effect 2
later parent effect
suspension_request

On continuation, the same sequence is offered again. Retained results are consumed without re-executing completed providers or mutations.

The current defect is the non-durable bridge around an operation that can yield durable effects: expand() runs through ephemeral() in packages/core/src/generated-xmd.ts. An ephemeral operation is journal-transparent and reruns on replay, so it cannot own a mixed expansion containing ordinary durable effects.

Use the existing owning document expansion. Do not create a child durable coroutine or another lifecycle owner.

Selected implementation boundary

• Make evaluateGeneratedXmd() an Operation<GeneratedObservationResult>.
• Make evaluateGeneratedFragment() and the workflow package's internal admission wrapper Operations.
• Yield the retained admission directly.
• Run complete-fragment preflight and the admitted expansion inline.
• Remove the ephemeral(expand(...)) boundary.
• Preserve the fragment's existing scoped() ownership for middleware, cancellation, and teardown.
• Keep policy comparison before the first nested provider or mutation.

This places the fragment's durable effects directly in the expansion operation already owned by the document.

Do not add durableSpawn, a child coroutine, flattened records, skipped history, or mutation reruns. DurablePreparation does not change, and @executablemd/durable-streams gains no schema, protocol, or primitive.

The trusted-host TypeScript surface widens from the narrower Workflow return type to Operation. The authored <Evaluate> API and journal schemas remain unchanged.

Host documentation that says the evaluator is reached from a DurablePreparation must be corrected: the workflow path reaches it through the trusted <Evaluate> component inside the owning document expansion.

Frozen acceptance evidence

1. A generated fragment containing a durable read resumes past a later suspension and completes.
2. A generated fragment containing a durable write resumes past a later suspension and completes.
3. The exact journal order is generated_xmd, every nested effect in authored order, later parent effects, then suspension_request.
4. Across resume, each completed read provider and mutation is invoked exactly once.
5. A changed retained admission policy refuses before any nested provider or mutation runs.
6. Empty fragments and fragments with no durable effects preserve their current behavior.
7. Existing GX15 and GX16 generated-XMD continuation controls remain green.
8. Existing GXC9 policy controls remain green.
9. The Compose the supervised adversarial implementation workflow #301 AC4 reproducer fails before the correction and completes after it, with the exact retained evidence reaching the Planner and checkpoint material and zero repeated evidence-provider reads.

The focused regression must distinguish start from resume and must assert provider/mutation call counts, not only the final result.

Implementation scope

A focused PR targeting current main owns:

• canonical generated-XMD execution in packages/core/src/generated-xmd.ts;
• the workflow admission wrapper and its types;
• generated-XMD read/write continuation regressions;
• architecture.md generated-XMD ownership wording;
• workflow specification §8.4 and §9;
• applicable executable-MDX GX/GXC/WGAC rows;
• a superseding decision-log clarification that mixed generated expansion offers its durable effects inline rather than hiding them behind a nested non-durable bridge.

Focused feedback evidence

Run the smallest explicit affected set, including the new continuation regression:

deno task test packages/core/tests/generated-xmd.test.ts packages/workflow/tests/generated-observations.test.ts packages/workflow/tests/workflow-suspension-answer.test.ts <new-continuation-regression>
git diff --check

Also run the exact #301 AC4 reproducer or an extracted equivalent against the corrected production path and report the journal order and provider/mutation invocation counts.

Create a feedback commit promptly once this frozen matrix passes. Return its exact SHA, exact base, every command/result, and a criterion-by-criterion evidence map. Implementation feedback does not wait for or inspect CI.

Out of scope

• Admission-policy, pinned-identity, allowed-effect, or authored <Evaluate> API changes.
• Durable effect-schema or journal-schema changes.
• Workspace transaction changes.
• Suspension, answer-delivery, cancellation, or teardown semantics.
• A new durable-stream primitive or protocol.
• A child durable coroutine, flattened history, skipped records, or replaying completed work.
• Production composition changes in PR ✨ Compose and certify the supervised adversarial implementation workflow #181 before this prerequisite merges.

Dependencies

• Evaluate Agent-generated XMD through a constrained allowlist #369 remains the historical generated-XMD admission delivery.
• ⏸️ Ask a person from a workflow, and wait for the answer durably #577 supplies the later suspension used by the end-to-end reproducer.
• Compose the supervised adversarial implementation workflow #301 / PR ✨ Compose and certify the supervised adversarial implementation workflow #181 is the blocked end-to-end consumer.
• End goal: ✨ Compose and certify the supervised adversarial implementation workflow #181.