---
name: write-section-promise
description: Crafts the one-sentence promise a substacker section makes to its reader — specific, testable, non-overlapping with other sections, written in the writer's voice (not marketing). Use when propose-section stages a new section or when an existing promise is being revised. Trigger keywords: section promise, one-sentence promise, section statement, reader promise.
---
# Write Section Promise
## Four tests
A promise passes if ALL of:
1. **Specific** — reader can predict what a post in this section will do for them.
2. **Testable** — point at a candidate post and say yes/no.
3. **Non-overlapping** — distinguishable from every other section's promise by at least one axis.
4. **Voiced** — reads as the writer's voice per `audience-notes.md` + `voice-profile.md`, not marketing copy.
## Workflow
```
For a candidate section:
- [ ] Step 1: Draft 3 candidate promises
- [ ] Step 2: Score each on the 4 tests
- [ ] Step 3: Pick highest-scoring
- [ ] Step 4: If none pass all 4, flag and return best-with-caveat
```
## Worked example
**Section**: Intuition-first ML (candidate).
- Draft A: "Essays about machine learning." — FAILS specific, FAILS non-overlap (too broad).
- Draft B: "We break down ML concepts." — FAILS voiced (marketing tone), FAILS testable.
- Draft C: "Essays that build geometric or mechanical intuition for how ML systems actually work, before the math." — PASSES all 4. Winner.
## Guardrails
1. ≤25 words. Longer promises become paragraphs and no one reads.
2. No buzzwords. No "we dive deep into X" or "unlock insights."
3. One sentence, not two.
4. Second person or declarative — never "I argue…"
5. Must fit the writer's voice per `audience-notes.md` + `voice-profile.md`.