feat: query language docs in swagger description

apps/web/src/index.ts

@@ -12,7 +12,99 @@ await migrate();
 
 const app = new Elysia()
   .use(cors())
-  .use(swagger({ path: "/docs", documentation: { info: { title: "PingQL API", version: "0.1.0" } } }))
+  .use(swagger({
+    path: "/docs",
+    documentation: {
+      info: {
+        title: "PingQL API",
+        version: "0.1.0",
+        description: `
+## Query Language
+
+A MongoDB-style query language for defining when a monitor is **up** or **down**.
+By default (no query), a monitor is up when HTTP status < 400.
+
+---
+
+### Fields
+
+| Field | Type | Description |
+|---|---|---|
+| \`status\` | number | HTTP status code |
+| \`body\` | string | Response body as text |
+| \`headers.<name>\` | string | Response header (e.g. \`headers.content-type\`) |
+| \`$responseTime\` | number | Latency in milliseconds |
+| \`$certExpiry\` | number | Days until SSL cert expires |
+| \`$json\` | object | JSONPath against response body |
+| \`$select\` | object | CSS selector against response HTML |
+
+---
+
+### Operators
+
+| Operator | Description |
+|---|---|
+| \`$eq\` \`$ne\` | Equal / not equal |
+| \`$gt\` \`$gte\` \`$lt\` \`$lte\` | Numeric comparison |
+| \`$contains\` \`$startsWith\` \`$endsWith\` | String matching |
+| \`$regex\` | Regular expression |
+| \`$exists\` | Field is present and non-null |
+| \`$in\` | Value is in array |
+| \`$and\` \`$or\` \`$not\` | Logical operators |
+
+---
+
+### Examples
+
+**Status code:**
+\`\`\`json
+{ "status": { "$lt": 400 } }
+\`\`\`
+
+**Body content:**
+\`\`\`json
+{ "body": { "$contains": "healthy" } }
+\`\`\`
+
+**JSON response field:**
+\`\`\`json
+{ "$json": { "$.data.status": { "$eq": "ok" } } }
+\`\`\`
+
+**CSS selector (HTML pages):**
+\`\`\`json
+{ "$select": { ".status-badge": { "$contains": "operational" } } }
+\`\`\`
+
+**Response time:**
+\`\`\`json
+{ "$responseTime": { "$lt": 500 } }
+\`\`\`
+
+**SSL cert expiry:**
+\`\`\`json
+{ "$certExpiry": { "$gt": 14 } }
+\`\`\`
+
+**Logical:**
+\`\`\`json
+{ "$and": [{ "status": 200 }, { "body": { "$contains": "ok" } }] }
+\`\`\`
+
+**$consider — mark DOWN when conditions match:**
+\`\`\`json
+{ "$consider": "down", "$responseTime": { "$gt": 2000 } }
+\`\`\`
+
+Full docs: [/dashboard/docs](/dashboard/docs)
+        `.trim(),
+      },
+      tags: [
+        { name: "account", description: "Account registration and settings" },
+        { name: "monitors", description: "Create and manage monitors" },
+      ],
+    },
+  }))
   .get("/", () => ({ name: "PingQL", version: "0.1.0", docs: "/docs", dashboard: "/dashboard" }), { detail: { hide: true } })
   .use(dashboard)
   .use(account)