## Red on main
```
workflow-ir-resolver > resolveWorkflowIrForTask > falls back to the built-in default when the definition is missing
workflow-ir-resolver > resolveWorkflowIrById > falls back to the canonical IR for an unknown built-in id
AssertionError: expected { version: 'v2', …(6), …(1) } to be { version: 'v2', …(6) }
Received: serializes to the same string
Compared values have no visual difference.
```
That message is the signature of an **identity-only** break, and that is
exactly what it is.
## Why identity can never hold again
Both asserted `toBe` against the exported builtin constant. **#2815**
added `markFellBack`:
```ts
function markFellBack(ir: WorkflowIr): WorkflowIr {
const copy = { ...ir } as WorkflowIr;
Object.defineProperty(copy, FELL_BACK_TO_DEFAULT, { value: true, enumerable: false, configurable: true });
return copy;
}
```
It brands the fallback so a caller can tell a **resolved** workflow from
a **guessed** one — the provenance contract #2618 introduced. Copying
*is* the mechanism, so these two paths cannot return the shared object.
Worth noting: the sibling `toBe` assertions in the same file **still
pass**. The no-selection and throwing-selection paths return the
constant unbranded, so only the two `markFellBack` paths changed — which
is why this presents as two failures rather than five, and why it is a
genuine contract change rather than a blanket refactor.
## Not just loosening to `toEqual`
Swapping `toBe` → `toEqual` alone would delete a real assertion. The
**brand is asserted too**, via the public provenance API rather than by
reaching for the private symbol:
```ts
expect(ir).toEqual(BUILTIN_STEPWISE_FINAL_REVIEW_CODING_WORKFLOW_IR);
const provenance = await resolveWorkflowIrForTaskWithProvenance(store, "t1");
expect(provenance.source).toBe("default");
```
This is **stronger** than the identity check it replaces:
| mutation | result |
|---|---|
| fallback no longer branded | **fails** — `expected 'selection' to be
'default'` |
| fallback returns a different IR entirely | **fails** structurally |
The first is the case the old `toBe` could not articulate: an unbranded
fallback still equals the constant structurally, so a caller asking
*"was this actually resolved?"* would get **yes for a guess** —
precisely the lie #2815 exists to prevent.
Core **4792 passed / 0 failed** (was 2 failed) · gate **732 green** ·
lint clean. Test-only; the resolver is restored clean after the
mutations.
## How it was found
Pre-flighting **#2822, #2819, #2823 and #2818** merged-with-main. All
four reported the *same two* failures — the signature of an inherited
red rather than four independent regressions. Confirmed directly on
`origin/main`. Each of those four is otherwise green (engine 11003
passed on all of them); I have noted that on the PRs.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>
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