Configuration

wrangler.toml (the whole file)

name = "plot-mcp-worker"
main = "src/index.ts"
compatibility_date = "2026-04-22"
workers_dev = true

[[routes]]
pattern = "your-worker.your-domain.com/*"
zone_name = "your-domain.com"

[[kv_namespaces]]
binding = "SHORT_LINKS"
id = "YOUR_KV_NAMESPACE_ID"
preview_id = "YOUR_KV_PREVIEW_NAMESPACE_ID"

[build]
command = ""

[[rules]]
type = "Data"
globs = ["**/*.ttf"]
fallthrough = true

KV namespace SHORT_LINKS

Binding name SHORT_LINKS. Three uses:

1. Short link records — key short:{8-char-token}, JSON value {path, payload}, TTL 30 days
2. Fonts (critical) — key font:arial-unicode-cn-gb2312 (TTF bytes), key font:arial-sans (TTF bytes), no TTL
3. Anything else? — no, those are the only two namespaces referenced in src/index.ts and src/render.ts

Font upload (one-time setup)

loadFonts in src/render.ts L79-97 fetches both fonts from KV on first PNG render. If either is missing, it throws No CJK font loaded from KV (...). The fonts must be uploaded as raw arrayBuffer:

wrangler kv:key put --binding=SHORT_LINKS   "font:arial-unicode-cn-gb2312"   --path=./fonts/ArialUnicodeCN.ttf

wrangler kv:key put --binding=SHORT_LINKS   "font:arial-sans"   --path=./fonts/ArialSans.ttf

The first font (CJK) is also parsed with opentype.js and used by pathifyCjkText to convert CJK glyphs and math unicode (π, ², ³, ∫, √, etc.) to SVG paths before resvg renders them. Without this, Chinese labels and math symbols render as □.

The [[rules]] for .ttf

Wrangler's default behavior tries to bundle TTF files into the worker script, which fails for large fonts. The rule { type = "Data", globs = ["**/*.ttf"], fallthrough = true } tells wrangler: treat .ttf files as data (separate asset) and fall through to the next matching rule. This is what lets the fonts live in KV instead of being inlined into the worker bundle.

Constants (from src/constants.ts)

TypeScript config (tsconfig.json)

{
  "compilerOptions": {
    "target": "ES2022",
    "module": "ES2022",
    "moduleResolution": "Bundler",
    "strict": true,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "types": ["@cloudflare/workers-types"]
  },
  "include": ["src/**/*.ts"]
}

ES2022 + strict mode. skipLibCheck skips checking @cloudflare/workers-types. Wrangler's Bundler resolution mode means you don't need to declare explicit import paths for the npm dependencies.