retention-design

name	retention-design
description	Design retention and engagement features using the Hook Model. Use when the user says "improve retention", "reduce churn", "make it habit-forming", "engagement design", "hook model", "trigger action reward", "users aren't coming back", "increase DAU/MAU", or wants to design features that bring users back repeatedly - even if they don't explicitly say "Hook Model".

Overview

Based on Hooked by Nir Eyal. The Hook Model is a four-phase loop that drives habit formation in products. Habits require frequent, perceived utility, and a degree of pain when the habit is disrupted. Products that become habits are harder to churn from - not because users are locked in, but because the product genuinely fills a need they return to automatically.

The four phases: Trigger - Action - Variable Reward - Investment

Use this skill ethically. Eyal's own caveat: design habits for products that genuinely improve users' lives. Manipulating users into unhealthy habits is both wrong and unsustainable.

Workflow

Step 1: Define the habit you want to create

What behavior should become automatic?

• Frequency target: daily / weekly / monthly?
• Context: when and where does this behavior occur?
• Current alternative: what do users do today instead?

Step 2: Design the Trigger

Triggers prompt action. Two types:

• External triggers - notifications, emails, badges, prompts (used early in habit formation)
• Internal triggers - emotions or situations that cue the behavior automatically ("I feel anxious - I open [app]")

The goal: move users from external to internal triggers over time.

For your feature: what external trigger will prompt first use? What internal trigger will sustain it?

Step 3: Design the Action

Eyal's formula: Motivation + Ability + Trigger = Action

Reduce friction on the action:

• How many steps to complete the action?
• What's the minimum viable action? (e.g. one tap, not a form)
• Where does motivation need to be highest? Remove barriers there.

Fogg's six elements of simplicity: time, money, physical effort, brain cycles, social deviation, non-routine. Reduce the one that's the biggest barrier.

Step 4: Design the Variable Reward

Variable rewards drive repeat behavior (Skinner's research). Three types:

• Rewards of the tribe - social validation, belonging (likes, comments, leaderboards)
• Rewards of the hunt - seeking resources or information (feed, search results, deals)
• Rewards of the self - mastery, completion, consistency (streaks, progress bars, achievements)

Key: variability is what makes rewards compelling. Predictable rewards lose their pull. Design for some uncertainty in the reward.

Step 5: Design the Investment

Investment makes users more likely to return. Four forms:

• Data - users store value (photos, notes, history)
• Content - users create things (posts, lists, playlists)
• Followers - social capital that exists only in your product
• Reputation/skill - progress that would be lost by leaving

Investment also loads the next trigger: "You have 3 unread notifications" brings users back.

Step 6: Map the full Hook loop

Draw the loop explicitly:

Trigger     -> [what prompts the behavior]
Action      -> [the simplest behavior]
Reward      -> [what the user gets, with some uncertainty]
Investment  -> [what the user puts in that makes them return]
             -> Next Trigger: [how investment loads the next trigger]

Step 7: Ethical check

Before shipping: would you be comfortable if users knew exactly how you designed this? Would you use this product yourself? Would you recommend it to someone you care about?

Anti-Patterns

1. Designing triggers without investment Bad: Sending notifications that bring users in but give them nothing to do. Good: Every trigger should lead to an action that builds investment.

2. Predictable rewards Bad: "You earned 10 points" every single time. Good: Variable - sometimes 10 points, sometimes a badge, sometimes a streak milestone. Variability sustains engagement.

3. Investment that traps instead of enriches Bad: Making it painful to leave (dark patterns, data hostage-taking). Good: Investment that genuinely improves the product for the user over time.

4. External triggers forever Bad: Users still need a push notification to open the app after 6 months. Good: Design toward internal triggers. If users don't develop internal triggers, the habit hasn't formed.

Quality Checklist

• Habit defined: behavior, frequency, context
• External trigger designed for acquisition
• Internal trigger identified for sustained habit
• Action reduced to minimum friction
• Variable reward designed (not fixed/predictable)
• Investment mechanism builds value users would lose by leaving
• Full Hook loop mapped explicitly
• Ethical check passed