Function createIfMissing

packages/infra/src/WorkflowEngineCosmos.ts:264–281

(
    body: T
  )

  // Atomic create-or-noop using a single-op batch — returns true if created.
  const createIfMissing = <T extends { readonly id: string; readonly _partitionKey: string }>(
    body: T
  ): Effect.Effect<boolean> =>
    Effect.gen(function*() {
      const resp = yield* Effect.promise(() =>
        container.items.batch(
          [{ operationType: "Create" as const, resourceBody: body }],
          body._partitionKey
        )
      )
      const r = resp.result?.[0]
      const code = r?.statusCode ?? 0
      if (code === 201) return true
      if (code === 409) return false
      return yield* Effect.die(
        new Error(`workflow-engine cosmos createIfMissing for ${body.id} failed: ${code}`)
      )
    })

  // Last-writer-wins upsert — used to overwrite a persisted *suspended* activity
  // result once it finally completes (create-only ops can't transition it).