Pmf Check

/pmf-check

Read brain/believers/index.md, brain/interviews/, brain/metrics/ (if exists), brain/runway.md. Use believer_density() from the brain MCP.

PMF is not one number. It's three signals that have to align. Any single signal alone is gameable. The triangulation is what's hard to fake.

Three signals

Signal 1 — Disappointment survey

Ask all current users (not cherry-picked):

"How would you feel if you could no longer use this product?"

Options:

• Very disappointed
• Somewhat disappointed
• Not disappointed
• N/A — I no longer use it

Threshold: ≥40% "very disappointed" = PMF signal.

If founder hasn't run this:

• Generate the survey form (Google Form / Typeform / Tally — the questions, not the platform)
• Tell them to send to all active users (not just believers)
• Aim for 30+ responses minimum

If founder has results, capture in brain/metrics/disappointment-survey.md:

# Disappointment survey

Captured: <date>
Sample size: <N responses>
Sent to: <user pool description — must be ALL users, not selected>

## Results
- Very disappointed: X% (N=...)
- Somewhat disappointed: Y% (N=...)
- Not disappointed: Z% (N=...)
- N/A: ...% (N=...)

## Verdict
<PASS (≥40%) / WEAK (25-39%) / FAIL (<25%)>

Signal 2 — Retention cohort

Day 7, 30, 90 retention curves. The shape matters more than the number.

• Flat at zero → no PMF. Users churn completely.
• Curve that flattens above zero → PMF signal. Some core group keeps using it.
• Rising curve → exceptional, rare. (Network effects working.)

Calculate from product analytics. If founder doesn't have this set up:

• Ask for raw data (CSV: user_id, signup_date, last_active_date, plus weekly active flags if available)
• Compute cohort retention manually (Day 1, 7, 14, 30, 60, 90)
• Output to brain/metrics/retention-cohorts.md

Verdict: PASS (curve flattens >0%), WEAK (asymptote near zero), FAIL (everyone gone by Day 30).

Signal 3 — Believer density (from /believers)

Run /believers if not recently run. Use believer_density() from brain MCP.

• <15% → PMF mirage (most users are tire-kickers)
• 15–30% → weak; refine targeting
• 30–50% → healthy
• ≥50% → strong, focused niche

Verdict: PASS (≥30%), WEAK (15-29%), FAIL (<15%).

Triangulation

Mark each signal:

                | Threshold        | Actual   | Verdict
----------------|------------------|----------|--------
Disappointment  | ≥40%             | __%      | ____
Retention       | curve flattens   | ____     | ____
Believer dens   | ≥30%             | __%      | ____

Final verdicts

• 3 of 3 PASS → STRONG PMF. Stage 2 → 3 gate met. Time to scale. Run /default-alive and /story; raise if needed.
• 2 of 3 PASS → PMF. Real signal but specific weakness. Fix the FAIL before scaling.
• 1 of 3 PASS → Pre-PMF. Early. Keep iterating in Stage 2. Don't scale yet.
• 0 PASS, or only believer density passes → PMF MIRAGE. Most dangerous state. Feels like PMF but isn't. Vanity metric pattern. Re-target or refine hypothesis.

Output: brain/metrics/pmf-check.md

# PMF check

Captured: <date>

## Disappointment survey
<copy of brain/metrics/disappointment-survey.md results>
Verdict: ___

## Retention
<cohort table>
Verdict: ___

## Believer density
<from believer_density()>
Verdict: ___

## Triangulation
<2 of 3 / 3 of 3 / etc.>
**Final: <Strong PMF / PMF / Pre-PMF / PMF Mirage>**

## Action
<one of: scale / address weakness X / iterate / re-target>

Anti-patterns to call out

• "I have 1000 signups" alone is not PMF — "Users without retention is acquisition, not PMF."
• Survey from cherry-picked users — "Must be ALL active users, not selected ones. Otherwise the bias makes it noise."
• Founder claims PMF before this skill runs — "PMF is the triangulation, not the vibe. Run the three checks."
• One signal screaming, two silent — "That's a vanity metric, not PMF. The triangulation is the safeguard."

Why this exists

Vanity metrics feel like progress; actionable metrics tell the truth. Until disappointment hits ≥40%, scaling acquisition is multiplying churn. Most founders think they have PMF when one user says something nice — real PMF is when most users would be heartbroken if you shut down.

This skill is the reality check before the scaling decision.

After /pmf-check returns Strong PMF: stage gate to 3 unlocks. Run /default-alive next to check whether you can fund the scale-up.