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Amends 0102: the engine sits behind a port, and Temporal is a supported driver.

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Context

0102 chose an in-process engine with a Postgres journal. The owner’s workflow answer FW9 (mem L544, 2026-10-20, with a correction at L542) requires the engine to be driver-agnostic: the same workflow runs on a native driver or on Temporal. Temporal’s checkpointed steps are activities, so a workflow body must be deterministic. This conflicts with the declarative graph of 0094. Contradiction C-09 is resolved as follows: the graph is the deterministic body, and the lint checks that its when and input expressions are pure.

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Decision

  1. Workflows are written once, with @Workflow and @Step. Checkpointed steps map to Temporal activities.
  2. The engine sits behind a WorkflowEngine port.
  3. The native driver is the default and costs nothing. It uses the Postgres outbox, queue and scheduler. It runs on Encore in SaaS, and needs no extra infrastructure on-prem.
  4. The Temporal driver is part of Pro. It runs on Temporal Cloud or self-hosted, and is chosen per environment.
  5. The workflow body is the declarative graph. A lint checks that each when and input expression is pure and deterministic.
  6. A conformance suite runs on both drivers.

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Consequences

  • A workflow author writes a graph, not imperative code, so the same workflow runs on either driver.
  • Temporal is a supported driver. The 0011 table needs a Temporal row; that change belongs to the final pass (ADR 0227).

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Enforcement

planned — the purity lint on when and input, and the conformance suite on both drivers. The lint and suite are not built yet.

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Alternatives

  • Imperative workflow bodies: rejected by 0094, and they would not be portable to Temporal’s model.
  • Native only: rejected, Temporal is a supported driver where a customer needs it.

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Supersedes and sources

Supersedes: none. Amends: 0102. Sources: owner workflow answer FW9 with its correction (stackra-decisions-2026-10-19.md L542, L544, 2026-10-20); the resolution of C-09 (stackra-notes/decision-register.md, contradictions table).