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name: feature-flag-plan description: > Plan feature flag implementations — flag types, lifecycle management, targeting rules, rollout strategies, cleanup processes, and tech debt prevention. TRIGGER when: user says /feature-flag-plan, needs to implement feature flags, or asks about progressive rollout strategies. argument-hint: "[system or project context]" user-invocable: true

Feature Flag Plan

You are a software delivery specialist. Design a feature flag strategy that enables safe progressive rollouts while managing technical debt.

Process

Step 1: Classify Flag Types

Type	Lifespan	Example	Cleanup
Release flag	Days-weeks	New feature rollout	Remove after 100% rollout
Experiment flag	Weeks	A/B test variant	Remove after decision
Ops flag	Permanent	Kill switch, circuit breaker	Keep, review annually
Permission flag	Permanent	Premium feature gating	Keep, managed by product

Step 2: Design Flag Lifecycle

Phase	Activities
Create	Define flag, set default (off), document purpose and owner
Configure	Set targeting rules, rollout percentage
Rollout	Progressive: 1% → 10% → 50% → 100% with monitoring
Evaluate	Measure impact, decide ship/revert
Cleanup	Remove flag code, delete flag definition, close ticket

Step 3: Define Targeting Rules

Rule Type	Use Case
Percentage	Gradual rollout to random % of users
User segment	Beta users, internal, enterprise tier
Geography	Region-specific launches
Device/platform	Mobile-only, desktop-only
Time-based	Enable during business hours only

Step 4: Set Monitoring Requirements

For each flag rollout, monitor:

Metric	Check
Error rates	No increase vs control
Performance	Latency within SLA
Business metrics	Conversion, engagement as expected
Rollback trigger	Auto-disable if error rate > threshold

Step 5: Prevent Technical Debt

Practice	Details
Expiration dates	Every release flag gets a cleanup deadline
Flag audit	Monthly review of all active flags
Stale flag alerts	Alert if flag is > 30 days old and still partial
Maximum active flags	Limit to N active release flags per service
Code review	Flag cleanup is part of the definition of done

Step 6: Select Tooling

Tool	Type	Strengths
LaunchDarkly	SaaS	Full-featured, enterprise, SDKs for all platforms
Unleash	Open source	Self-hosted, good feature set
Flagsmith	Open source/SaaS	Simple, good API
Split	SaaS	Experimentation focus
Custom	In-house	Full control, no vendor dependency

Output Format

## Feature Flag Plan: [Feature Name]
### Flag: [name] | Type: [release/experiment/ops/permission]
### Targeting: [rules]
### Rollout: [phase plan with percentages]
### Monitoring: [metrics to watch]
### Cleanup: [deadline and owner]

Quality Checklist

• Flag type and lifecycle are defined
• Targeting rules are documented
• Monitoring is configured before rollout
• Rollback mechanism tested
• Cleanup deadline set
• No more than N active release flags

Edge Cases

• For server + client flags, ensure consistency (avoid flicker)
• If flag evaluation is latency-sensitive, use local evaluation with cached config
• For flags that control database migrations, plan carefully (can't easily toggle back)
• If regulations require audit trails, ensure flag changes are logged