refactor(service-automation): move AutomationEngine.resumeInternal's body into run-resume.ts (#25222 slice 8b) (#25734)

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Part of #25222

Clause-②: no
Metadata-protocol: none

Slice 8b of the `engine.ts` split, move-only, under claim `6392268076`
(Ruling-ref `6384677413`, ruling B; `6348891160`, the series' `.d.ts`
bar). Scope is Release `6385919610`'s 8b paragraph: `resumeInternal`
moves alone into `run-resume.ts`.

**Is this the last slice?** It is the last slice the Release plans. With
8a (#25725) and this PR, slice 8 is done; the six bodies the Release
keeps in the class stay there. Whether the card closes is the seat's
call, so this PR does not close it.

## What moves

- `AutomationEngine.resumeInternal`'s body (919 lines in the class)
becomes `export async function resumeInternal` at the end of
`run-resume.ts`, moved unedited. The class keeps the private method: its
name, docblock, parameter comment and signature stay. The stub calls the
body with a host literal and is no longer `async`; it returns the
promise the moved function makes.
- `RunResumeHost` gains 14 members, so it now holds 41. The function's
`this` is a Pick of `RunResumeHost` over the 25 members the body reads.
- `logger`, `flows`, `resuming` and `consumedSuspensions` go by value.
Each one is assigned only at its declaration or in the constructor. The
other 21 are late-bound method closures, so a spy or test double set on
the instance is still the one called.
- **Recursion stays on the class.** The body's own recursive call
(`this.resumeInternal(childRunId, signal, true)`) goes through the host
closure into the class stub. `bubbleToParent`'s call stays in the class
and calls the stub directly. `subflow-hosted-approval-strand.test.ts` in
plugin-approvals patches `resumeInternal` on the instance, and both
paths still reach that patch.
- **Four in-place exports in `engine.ts`**, the ones the Release names:
`ChildRunRefusal`, `isRetryableResumeRefusal`,
`carriesSubflowChildOutput` and `applyResumeSignal`.
`ENGINE_BUILT_SIGNAL` stays unexported. The body reads no other
unexported `engine.ts` name; a TypeScript checker pass over the base
method listed exactly these four.
- `run-resume.ts` imports `readCarriedRefusal` and `summarizeRun`
directly. From `./engine.js` it also takes `FlowRefusalSignal`,
`isRefusalSignal`, `isSuspendSignal`, the three new value exports and
the types `ChildRunRefusal` and `ExecutionLogEntry`. Those values are
read only at call time, so the cycle comment now lists all seven.

Size: 2 files, 1,898 changed lines (+985 / -913). `engine.ts` goes from
9,882 to 9,006 lines. `check-governed-merges --branch HEAD` says NOT
governed, with 0 of 2 paths on the register, under 3,000 lines.

## Proof that it moved nothing

All readings below were taken in this container on head `d8bf1026`
against base `f3fea0a03d`, the merge base and `origin/main` at the time.

- **AST token identity** (TypeScript 6.0.3). The base method and the
head function compare IDENTICAL on body leaf tokens (kind and text,
1,754 tokens), on parameters (17 tokens, with the head's `this`
parameter dropped), on the return type (4 tokens) and on the `async`
modifier.
- **Negative control.** In a scratch copy of the head `run-resume.ts`, I
changed one token: `this.resuming.delete(runId)` became
`this.resuming.add(runId)`. Grep confirmed the edit landed (delete went
1 to 0, add went 1 to 2), and the comparison reads DIFFERENT with exit
1.
- **Line accounting.** Every line deleted from `engine.ts` reappears,
dedented four spaces, among `run-resume.ts`'s added lines. The five
exceptions are the four declaration lines that gained `export` and the
method's `private async` head line.
- **Host sets.** The `this.X` reads in the head body, the Pick keys and
the stub's host-literal keys are the same 25 names. Every Pick key is
declared on `RunResumeHost`.
- **`.d.ts`.** `dist/index.d.ts` and `dist/index.d.cts` are raw
byte-identical at base and head, both sha256
`a5cbe3bbb8aff2805674e1d9f119946199697e469a3e8a5b9bc7eb4fc08bc7cb`. Raw
identity holds, so the sorted-union bar holds trivially. The head
`index.js` does contain the new `async function resumeInternal(` and
base does not, so the head build is real.
- **Export lists.** ESM and CJS each export 39 names, the same list in
both bundles. The fingerprint over name, typeof and function name is
`afcfb4e8069c1e10` at both ends.
- **Hand readers, byte-identical output at base and head** (sha256
prefixes):
- `check-startup-registry-verdict`: 46 seams, 39 read-only
(`9209def6…`). Its `--self-test` is `fb8c875f…`. Its `--list` matches
apart from line numbers, including `registerFlow`'s line.
- `check-tenant-audit-census` (`52b71dc0…`): 239 sites certified, 163
decidable, 23 prose figures. Its `--self-test` is `fae0925f…`.
- `tenant-audit-census`: human output `b1d732d2…`, and `--json` without
`measuredAt` `dc3ff45e…`.
- `check-system-context-census` (`6db2898d…`) and `isystem-census
--json` (`fb320be9…`).
- `check-platform-checklist` (`edee137b…`), `check-adr-symbol-anchors`
(`7530e478…`) and `check-adr-anchors` (`1b79d342…`).

## Tests and gates

- `@objectstack/service-automation` vitest on head: Test Files 201
passed (201), Tests 2636 passed (2636).
- Package `typecheck` (`tsc --noEmit` plus `check:test-typecheck`) exits
0. ESLint `--no-inline-config` over
`packages/services/service-automation` exits 0.
- `dispatch-gates --commands --repo objectstack-ai/objectstack` derives
54 families on the 2 paths, and all 54 exit 0. Two of them first exited
3, PREREQUISITE NOT MET, and passed on re-run without any change to the
code:
- `check-plugin-teardown-shape --self-test` passed (48 cases) once the
fixture commit `621a4876` was fetched into the shallow clone.
  - `check:dual-build-cjs-loads` passed after a full `pnpm build`.
- `--ran` reconciles: 54 derived, 54 run, 0 NOT-MEASURED, 0 UNRUN.

## Acceptance notes

- Comments inside the moved body that point by position ("the docblock
above", "below") moved unedited, as in slices 1 to 8a.
- Serial constraints, re-checked before this PR was opened: none of the
20 open PRs touches `engine.ts` or `run-resume.ts`. 18 were diffed
against their merge base. #25588 (docs, pm-dispatch) and #25569 (cli
CSP) have no merge base in this shallow clone, so I judged those two by
title only.

---
_Generated by [Claude
Code](https://claude.ai/code/session_01Rg1PtyxbtSpabeP7j6fq8Y)_

Co-authored-by: Claude <noreply@anthropic.com>

Author: objectstack-fleet[bot]