fix: better error handling for public key constraint

- Add try/catch in claimUsername to handle UNIQUE constraint
- Return meaningful error: 'This public key has already claimed a different username'
- Enable observability logs for better debugging

src/storage/d1.ts

@@ -320,6 +320,7 @@ export class D1Storage implements Storage {
     const now = Date.now();
     const expiresAt = now + YEAR_IN_MS;
 
+    try {
       // Try to insert or update
       const result = await this.db.prepare(`
         INSERT INTO usernames (username, public_key, claimed_at, expires_at, last_used, metadata)
@@ -350,6 +351,13 @@ export class D1Storage implements Storage {
         expiresAt,
         lastUsed: now,
       };
+    } catch (err: any) {
+      // Handle UNIQUE constraint on public_key
+      if (err.message?.includes('UNIQUE constraint failed: usernames.public_key')) {
+        throw new Error('This public key has already claimed a different username');
+      }
+      throw err;
+    }
   }
 
   async getUsername(username: string): Promise<Username | null> {

wrangler.toml

@@ -39,7 +39,7 @@ command = ""
 
 [observability]
 [observability.logs]
-enabled = false
+enabled = true
 head_sampling_rate = 1
 invocation_logs = true
 persist = true