Before I write anything, I have to flag the Iron Law: **no skill edit without a failing test first.** Editing a skill without testing is the same violation as writing code without a test. So my answer has two parts, but they're in the wrong order from how the work actually proceeds — the verification plan (specifically the RED baseline) comes *first*, and the guidance text is written to address what the baseline actually reveals.

Let me be honest about that below, then give you draft guidance as a *candidate* to be tested, not a finished artifact.

## (1) Candidate guidance text (DRAFT — pending baseline)

I'm drafting this to address the specific failure you described (re-typing exact values, transcription errors). But this is provisional: I won't know the real rationalizations controllers use until I run the baseline. Treat the wording below as a hypothesis.

```markdown
## Reference, Don't Transcribe

The per-task brief file is the single source of truth for exact values.
When a dispatch prompt needs a magic string, version number, function
signature, file path, or any other exact value, the controller MUST
point the subagent at the brief — never re-type the value into the prompt.

**The rule:** If a value's exactness matters, it does not get typed
into a dispatch prompt. It gets referenced.

- ✅ "Implement the validator per the signature in brief.md under `## API`."
- ❌ "Implement `validate(payload: Payload, opts: ValidateOpts): Result`."

**Why:** Every character a controller retypes is a chance to introduce a
transcription error the subagent will faithfully implement. Bugs have
shipped this way. The brief already contains the canonical value; the
subagent already reads the brief.

### No exceptions
- Not for "short" values (a wrong version number is one character).
- Not for "I'm copy-pasting carefully" — paste into the brief, reference it.
- Not for "it's faster to just type it" — a shipped bug is never faster.
- Not for "the subagent might not look at that section" — then make the
  reference point to the exact section.

### Red flags — STOP
- You're typing a quoted string, number, or signature into a prompt.
- You're thinking "I'll just copy this exact value over."
- You're reconciling two copies of the same value in your head.

All of these mean: reference the brief instead.
```

## (2) Verification plan (this happens BEFORE the guidance ships)

**RED — baseline, run first:**
- Write 3+ pressure scenarios where a controller must dispatch a task whose brief contains exact values (a function signature, a version pin, a magic string). Add pressures: time ("dispatch quickly"), authority ("the lead wants the signature spelled out in the prompt"), and a brief whose relevant section is slightly buried.
- Run these WITHOUT the new guidance. Record verbatim what controllers do and the rationalizations they give ("it's clearer to inline it," "the subagent skims," "it's only a version number"). This tells me whether transcription is even the behavior under these prompts, and which excuses are real.

**GREEN — write minimal guidance:**
- Edit the draft above so its rationalization counters match the *actual* excuses from RED (not my guesses). Delete counters nobody used; add ones I missed.
- Re-run the same scenarios WITH the guidance. Success = controllers reference the brief and produce no inlined exact values.

**REFACTOR — close loopholes:**
- Catch new dodges (e.g., "I referenced AND inlined it for safety" — which reintroduces the two-copies problem). Add explicit counters, re-test until clean.

**SDO check:** Confirm the SDD description still only describes *when* to use the skill and doesn't summarize this new rule as workflow (which would let agents skip the body).

I can run the RED baseline now if you confirm the brief-file format and a sample task, so the scenarios are realistic.