Retention Loop Design Skill

Acquisition without retention is a leaky bucket — you pay to fill it and it drains. This skill diagnoses where and why users drop, then designs the loop that makes the product habitual: the trigger that brings them back, the value they get, and the investment that makes the next visit more likely. Retention is the truest measure of product-market fit.

Required Inputs

Ask for these only if they aren't already provided:

• The retention curve — how usage decays over time (D1/D7/D30, or weekly cohorts); does it flatten or go to zero?
• The core value & natural frequency — what users come for, and how often they'd genuinely need it.
• Activation definition — the early action that correlates with sticking (or note it's unknown).
• Current loops — any notifications, streaks, or re-engagement already in place.

Output Format

Retention Design: [product]

1. Curve diagnosis — read the retention curve: does it flatten (a retained core exists — good) or decay to zero (no PMF for this segment)? Identify the drop-off point and the cohort that retains best (your beachhead).

2. Activation → habit — the early "setup moment" and the habit milestone (e.g. "3 sessions in week 1"); the shortest path to it, since activation is the strongest lever on long-term retention.

3. The core loop — design the engagement loop explicitly:

• Trigger — external (notification, email) and the internal trigger you want to own (the felt need).
• Action — the simplest behaviour that delivers value.
• Reward — the value/variable reward received.
• Investment — what the user puts in (data, content, social, configuration) that makes the next loop better and raises switching cost.

4. Natural frequency match — align the loop's cadence to how often the job actually recurs; don't manufacture engagement the product doesn't warrant.

5. Re-engagement — triggered winback for users sliding toward churn (behavioural signal → message → return path); pair with [lifecycle-crm-plan](../lifecycle-crm-plan/SKILL.md).

6. Metrics — the retention metric and cohort view to watch, plus the leading indicator (habit-milestone rate) that predicts it.

Quality Checks

• The retention curve is diagnosed as flattening vs. decaying — that determines whether to fix retention or fix fit first
• Activation/habit milestone is defined and tied to long-term retention
• The loop names a trigger, action, reward, AND investment (the investment is what compounds)
• Loop cadence matches the product's natural frequency — no manufactured engagement
• A leading indicator (not just lagging retention) is identified to act on early

Anti-Patterns

• Do not optimise retention before the curve flattens for some segment — if it decays to zero there's no PMF to retain, fix that first
• Do not bolt on streaks/badges without a real reward — gamification on a product with no core value just annoys
• Do not spam notifications to force engagement — manufactured frequency drives uninstalls and erodes trust
• Do not ignore the investment phase — without stored value/data, there's nothing raising the cost of leaving
• Do not report only average retention — cohorts and the best-retaining segment tell you where to aim

Based On

The Hook Model (Nir Eyal) and cohort-retention analysis practice (flattening curve = PMF signal).