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Implement a feature flag system for toggles, gradual rollout, and targeting. Do NOT use for configuration management, A/B test analytics, or infrastructure feature flags.
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SOC 職業分類に基づく
Use to implement a REST or GraphQL API endpoint from a specification or description, including request validation, error handling, and accompanying tests. Activate for building a new API route, resolver, or handler end-to-end. Do NOT use for API design/contract creation, documentation generation, or frontend API consumption.
Use to implement background job processing with a queue, worker, retry with exponential backoff, dead letter queue, and monitoring. Activate when the request involves offloading work from the request cycle (emails, reports, data processing). Do NOT use for real-time event streaming, webhook handling, or scheduled cron jobs.
Use to scaffold a new project from scratch — generating directory structure, configuration files, entry points, and a README skeleton. Activate when starting a new project, service, or package and needing a production-ready starting point. Do NOT use for adding features to existing projects, generating tests, or CI/CD configuration.
Use to design and implement a caching layer for data that is expensive to compute or fetch. Activate for cache-aside, write-through, or write-behind patterns, TTL strategy, and cache invalidation logic. Do NOT use for database query optimization, CDN configuration, or HTTP response caching headers.
Use to generate a CI/CD pipeline configuration for building, testing, and deploying an application. Activate for GitHub Actions, GitLab CI, CircleCI, or similar pipeline tools for any tech stack. Do NOT use for infrastructure provisioning, Dockerfile creation, or deployment strategy design.
Use to generate production-ready code for a new feature, function, class, or module from a description. Activate for writing new code from scratch with error handling, inline documentation, and a self-review checklist. Do NOT use for refactoring existing code, code review, or test generation.
| name | feature-flag-implementation |
| description | Implement a feature flag system for toggles, gradual rollout, and targeting. Do NOT use for configuration management, A/B test analytics, or infrastructure feature flags. |
| version | 1.1.0 |
| time_saved | Manual: 2–4 hours | With skill: 15–25 minutes |
| license | Proprietary — Personal Use Only |
| category | coding |
| complexity | Intermediate |
| tokens | ~3000 |
| tags | ["feature-flags","feature-toggles","gradual-rollout","canary-release","a-b-testing"] |
| author | vheins |
Implement a complete feature flag system supporting toggles, percentage rollouts, and targeting.
| Variable | Type | Req | Description |
|---|---|---|---|
tech_stack | string | Yes | e.g., "Node.js + Redis" |
feature_description | string | Yes | Behavior, audience, and rollout plan |
flag_requirements | string | Yes | Storage backend and evaluation context |
| Case | Strategy |
|---|---|
| Hot paths | Apply aggressive short-TTL in-memory caching. |
| Flag dependencies | Avoid nesting; combine into single multi-state flags. |
| Client-side logic | Evaluate on server; pass results to frontend at page load. |
flowchart TD
A([Start: Feature Flag Implementation]) --> B[Define flag scope: release/experiment/ops/permission]
B --> C{Flag storage strategy?}
C -- Config file --> D[Static flags: env vars or JSON config]
C -- Remote service --> E[Integrate flag provider: LaunchDarkly/Unleash]
C -- Database --> F[DB-backed flags with admin UI]
D & E & F --> G[Define flag schema: name, type, default, description]
G --> H{Flag type?}
H -- Boolean --> I[Simple on/off toggle]
H -- Multivariate --> J[Multiple variants with weights]
H -- Percentage rollout --> K[Gradual rollout by user/session hash]
I & J & K --> L[Implement flag evaluation function]
L --> M{Targeting rules needed?}
M -- Yes --> N[Add user/context targeting: segment, attribute, env]
M -- No --> O[Wrap feature code with flag check]
N --> O
O --> P{Flag affects multiple layers?}
P -- Yes --> Q[Propagate flag context: API → service → DB layer]
P -- No --> R[Single-layer guard only]
Q & R --> S[Add flag state to observability/logging]
S --> T{Stale flags cleanup?}
T -- Yes --> U[Mark flags with expiry/owner/ticket ref]
T -- No --> V[Document flag inventory + rollback procedure]
U --> V
V --> W([Output: Feature flag system with targeting & rollback])
@upstash/context7-mcp: Library documentation and examples.| Version | Date | Description |
|---|---|---|
| 1.1.0 | 2026-03-20 | Restructured: moved examples/references, added compatibility/license |
| 1.0.0 | 2026-03-20 | Initial release |