feat: add self-optimizing adaptive rate limiting with automatic retry

.gitignore

@@ -7,6 +7,9 @@ node_modules/
 # aider
 .aider*
 
+# claude
+.claude/
+
 # eslint cache
 .eslintcache
 

src/lib/error.ts

@@ -3,20 +3,57 @@ import type { ContentfulStatusCode } from "hono/utils/http-status"
 
 import consola from "consola"
 
+import { RateLimitError } from "./retry"
+
 export class HTTPError extends Error {
   response: Response
+  errorBody?: string
 
-  constructor(message: string, response: Response) {
+  constructor(message: string, response: Response, errorBody?: string) {
     super(message)
     this.response = response
+    this.errorBody = errorBody
   }
 }
 
 export async function forwardError(c: Context, error: unknown) {
   consola.error("Error occurred:", error)
 
+  // Handle rate limit errors with detailed retry information
+  if (error instanceof RateLimitError) {
+    const retryAfter = error.retryInfo.retryAfter
+    const message =
+      error.retryInfo.exceeded ?
+        `Rate limit exceeded: ${error.retryInfo.exceeded}. Retry after ${retryAfter} seconds.`
+      : `Rate limit exceeded. Retry after ${retryAfter} seconds.`
+
+    return c.json(
+      {
+        error: {
+          message,
+          type: "rate_limit_error",
+          retry_after: retryAfter,
+          exceeded: error.retryInfo.exceeded,
+        },
+      },
+      429,
+      {
+        "Retry-After": retryAfter.toString(),
+      },
+    )
+  }
+
   if (error instanceof HTTPError) {
-    const errorText = await error.response.text()
+    // Use cached error body if available, otherwise try to read it
+    let errorText = error.errorBody
+    if (!errorText) {
+      try {
+        errorText = await error.response.text()
+      } catch {
+        errorText = "Failed to read error body"
+      }
+    }
+
     let errorJson: unknown
     try {
       errorJson = JSON.parse(errorText)