deno.json Configuration Standards

This rule applies to files matching the patterns above.

# deno.json Configuration Standards

## Rule
All Deno projects MUST use deno.json (or deno.jsonc) as the single source of configuration. Never rely on scattered CLI flags when deno.json options exist.

## Format
```json
{
  "compilerOptions": {
    "strict": true,
    "noUnusedLocals": true,
    "noUnusedParameters": true
  },
  "imports": {
    "@std/": "jsr:@std/",
    "@/": "./src/"
  },
  "tasks": {
    "dev": "deno run --watch --allow-net --allow-read src/main.ts",
    "test": "deno test --allow-read",
    "lint": "deno lint",
    "fmt": "deno fmt"
  },
  "lint": {
    "rules": { "tags": ["recommended"] }
  },
  "fmt": {
    "indentWidth": 2,
    "singleQuote": false
  }
}
```

## Good Examples
```jsonc
// deno.jsonc — with comments for documentation
{
  "compilerOptions": {
    "strict": true,
    "jsx": "react-jsx",
    "jsxImportSource": "preact"
  },
  // Use JSR for standard library
  "imports": {
    "@std/path": "jsr:@std/path@^1",
    "@std/assert": "jsr:@std/assert@^1",
    "oak": "jsr:@oak/oak@^16"
  },
  "tasks": {
    "dev": "deno run --watch --allow-net --allow-env --allow-read src/main.ts",
    "test": "deno test --allow-read --coverage=coverage",
    "check": "deno check src/**/*.ts"
  }
}
```

## Bad Examples
```bash
# BAD: CLI flags instead of deno.json tasks
deno run --allow-net --allow-read --allow-env --allow-write --unstable-kv src/main.ts
# This belongs in a deno.json task

# BAD: URL imports without import map
import { serve } from "https://deno.land/std@0.220.0/http/server.ts";
# Use JSR imports in deno.json instead
```

## Enforcement
- `deno check` validates TypeScript without running
- `deno lint` enforces lint rules from deno.json
- CI runs `deno fmt --check` to verify formatting