environment-setup（环境设置）

Environment Configuration

Use this skill as the repository's narrower application-config and .env compatibility skill.

The job is to make app configuration clear and safe across environments:

• decide what belongs in env vars,
• structure .env files and precedence rules,
• validate required config,
• separate public/private values,
• reduce config drift between local, CI, staging, and production,
• make secret handoff explicit.

Read references/env-patterns.md and references/scope-boundaries.md before unusual cases or when deciding whether the real need belongs in system-environment-setup.

If the user mainly needs:

• toolchains, local services, Docker Compose, devcontainers, or onboarding → route to system-environment-setup
• deployment or CI secret wiring → pair with deployment-automation
• security architecture or policy → pair with security-best-practices

When to use this skill

• Design .env.example, .env.local, or per-environment config structure
• Explain env precedence and which values should or should not be committed
• Validate required env vars with typed/runtime checks
• Separate server-only vs client-exposed env values
• Reduce drift between local, CI, staging, and production config
• Clean up a repo where env files, secret docs, and runtime expectations disagree
• Decide when env vars are enough and when secret-manager injection is needed

When not to use this skill

• The main task is making the full repo runnable across machines → use system-environment-setup
• The main task is local service orchestration, Docker, or devcontainers → use system-environment-setup
• The main task is deployment automation or production rollout → use deployment-automation
• The main task is broader security review rather than config organization → pair with security-best-practices

Instructions

Step 1: Classify the config problem

Normalize the request into this intake first:

env_config_intake:
  primary_goal: env-structure | validation | secret-handoff | public-private-split | drift-cleanup | framework-rules | unknown
  app_shape: backend | frontend | fullstack | monorepo | unknown
  current_storage: env-files | framework-config | secret-manager | mixed | unknown
  drift_surface:
    - missing-required-vars
    - duplicate-env-files
    - CI-local-mismatch
    - public-private-leak-risk
    - undocumented-secret-source
    - framework-prefix-confusion
    - unclear
  confidence: high | medium | low

Step 2: Choose one primary mode

Pick exactly one mode for the run:

1. env-file-structure

- Use when the main need is file layout, naming, and precedence.

1. env-validation

- Use when missing or malformed values are causing runtime/build pain.

1. secret-handoff-boundary

- Use when .env files are colliding with secret-manager or credential-delivery concerns.

1. framework-config-rules

- Use when the main problem is framework-specific env behavior (public/private prefixes, build-time vs runtime exposure, etc.).

1. drift-cleanup

- Use when env templates, docs, CI vars, and actual runtime expectations disagree.

Step 3: Apply config rules

• Keep deploy-specific values out of source code and commit only safe templates.
• Separate committed templates from developer-local values.
• Make public/client-exposed env vars visually distinct from server-only values.
• Prefer typed validation when the app is large enough for env drift to be expensive.
• Record the source of secrets: local file, secret manager, CI variable, or cloud platform.
• Route outward when the actual blocker is machine setup, Docker, or local services rather than config design.

Step 4: Build the config brief

Return this exact structure:

# Environment Config Brief

## Recommended mode
- Mode: env-file-structure | env-validation | secret-handoff-boundary | framework-config-rules | drift-cleanup
- Why this mode fits: ...

## Current config surface
- App shape: ...
- Config sources: ...
- Main drift or risk: ...
- Confidence: high | medium | low

## Recommended config layout
1. ...
2. ...
3. ...

## Example files / checks

...

## Why this layout is safer

- ...
- ...

## Watch-outs

- ...
- ...

## Adjacent handoff

- Use `system-environment-setup` for...
- Use `deployment-automation` for...
- Use `security-best-practices` for...

Step 5: Use mode-specific guidance

For env-file-structure

• Define the committed template files first.
• Call out local-only overrides and ignored files explicitly.
• Make precedence easy to explain.

For env-validation

• Choose a schema/validation layer appropriate for the stack.
• Fail fast with clear missing-variable messages.
• Keep validation close to app startup.

For secret-handoff-boundary

• Name which values are safe in templates and which must come from a secret source.
• Document how a developer obtains sensitive values.
• Avoid pretending secret-manager adoption removes the need for local conventions.

For framework-config-rules

• Explain public/private env prefixes and build-time/runtime behavior.
• Call out framework-specific exposure risks.

For drift-cleanup

• Compare templates, runtime code, CI vars, and docs.
• Remove duplicate or stale env file conventions.
• Make one source of truth obvious.

Step 6: Keep boundaries sharp

Before finalizing:

• Do not turn this into a Docker/devcontainer tutorial.
• Do not bury public/private env exposure risk.
• Do not assume .env files are enough for all secret workflows.
• Do not keep this as a peer duplicate of system-environment-setup; route broader setup work outward.

Examples

Example 1: Env template cleanup

Input: "Help me structure .env.example and .env.local so new devs stop guessing values." Output: chooses env-file-structure, defines committed templates vs local overrides, and keeps the scope at app config.

Example 2: Validation hardening

Input: "We keep forgetting env vars until runtime." Output: chooses env-validation, recommends typed validation, and shows how to fail fast.

Example 3: Framework split

Input: "Which env vars can be exposed to the frontend and which must stay server-only?" Output: chooses framework-config-rules, explains the client/server split, and avoids broad setup drift.

Best practices

1. Treat this as the app-config layer, not the whole-machine setup skill.
2. Make secret sources explicit rather than implied.
3. Prefer committed templates plus local-only overrides.
4. Add validation once env drift becomes expensive.
5. Route broader runnable-repo work to system-environment-setup.

References

• Environment patterns
• Scope boundaries
• Twelve-Factor config
• Next.js env guide
• T3 Env intro