README Generator

Create/update README.md in project root. Constraints: < 200 lines, scannable in 30 seconds, technical tone (no marketing).

Additional Instructions

$ARGUMENTS

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Analysis Phase

Check files in order, record findings:

1. flake.nix → Nix flake present (Y/N)
2. .envrc + .envrc.example → direnv present (Y/N)
3. Makefile → Make targets available (Y/N)
4. package.json / pyproject.toml / go.mod / Cargo.toml → Language ecosystem
5. Existing README.md → Preserve badges, screenshots, custom sections
6. Entry points → main.py, index.ts, cmd/main.go, etc

Build System Priority

Select primary build interface based on presence:

Priority	System	When	Commands
1	Nix	flake.nix exists	nix develop, nix build, nix run
2	Make	Makefile exists	make install, make test, make build
3	Package manager	package.json / Cargo.toml	npm install, cargo build
4	Direct	None above	python -m, go run, etc

If multiple exist: Use highest priority as primary, mention others as alternatives.

Environment Management

If .envrc exists:

• Prerequisites: Add "direnv" requirement
• Install step: Add cp .envrc.example .envrc && direnv allow
• Configuration section: Reference .envrc.example for variables

If no direnv:

• Use .env files or manual export commands
• Configuration section: List env vars inline

README Composition

Required sections (generate in order):

1. Title + Summary

# [Project Name]
> [Single sentence: does X for Y users]

2. Quick Start

Prerequisites: List tools with versions. Omit language version if Nix manages it. Include Nix/direnv if detected.

Install: Commands to get dependencies. Prioritize by build system table above.

Run: Command to start/execute. Include port/URL for web apps.

Test: Command to run tests. Use nix flake check if available.

3. Project Structure

Tree diagram of key directories with inline comments:

src/
  core/       # Business logic
  api/        # Endpoints
tests/        # Test suite

4. Development

Setup: Additional dev steps (direnv, pre-commit hooks, etc)

Build/Lint/Format: Commands using primary build system

Common tasks: 2-3 bullet points for frequent operations

5. Optional Sections (include only if applicable)

Architecture: 2-3 sentences on design decisions and tradeoffs. Include if non-obvious.

Configuration: Env vars with descriptions. Required vs optional. Include if app needs config.

Deployment: Deploy command or link. Include for deployable apps.

Contributing: Link to CONTRIBUTING.md or inline if < 5 rules.

License: License type. Include if LICENSE file exists.

Output Format Rules

Command syntax:

• Multi-word commands: Always use code blocks, never inline
• Good: "Run:\nbash\nnpm run dev\n"
• Bad: "Run npm run dev"

Section length: Each section < 15 lines. Link to detailed docs if longer.

Style: Technical, direct. Explain WHY for architecture, not WHAT code does. No "easy", "simple", "just".

Preservation: Keep existing badges, screenshots, unique sections from old README.

Project Type Adaptations

Type	Adaptations
CLI tool	Add "Usage" with examples, omit "Running"
Library	Add "Installation" + "Usage" with API examples, omit "Running"
Web app	Include PORT/URL in "Run", add "Deployment"
Monorepo	Show workspace structure, document per-package commands
Nix multi-output	Add nix flake show output, document available apps/packages

Execution Workflow

1. Run analysis phase → Collect build system, env management, project type
2. Generate README content using composition rules
3. Show preview with summary: "[Project type] with [build system]. README uses [commands]. ~[N] lines."
4. If approved → Write to README.md
5. If rejected → Ask what to change, regenerate from step 2

Edge Cases

No build system found: Use direct language commands (python, go run, etc) and warn in preview.

Nix without devShell: Use nix-shell or nix develop with warnings about flake completeness.

Multiple entry points: List all in "Run" section with descriptions.

Secrets in .envrc: Never read actual .envrc, only .envrc.example. Remind about .gitignore.

Example Execution

Input: "Generate README"

Analysis:

• flake.nix: Yes (Nix development shell + app)
• .envrc: Yes (with .envrc.example)
• Makefile: Yes (install/test/build targets)
• package.json: Yes (Next.js)
• Entry: pages/index.tsx

Build priority: Nix (priority 1), mention Make as fallback

Preview: "Next.js web app with Nix flake and direnv. README uses nix run for primary interface, notes make commands as alternative. Includes .envrc.example setup. ~90 lines. Approve?"

Output: README.md with Nix-first commands, direnv setup, project structure showing pages/ and components/, development section with nix build and nix flake check.