Print a more sensible error when the user's edge preview token is expired

src/cloudflare/internal/ai-api.ts

@@ -386,6 +386,14 @@ export class Ai {
         return new InferenceUpstreamError(content);
       }
     } catch {
+      // FL2 returns a plain text "error code: 1031" response when the edge
+      // preview token has expired (e.g. during `wrangler dev`).
+      if (content.includes('error code: 1031')) {
+        return new InferenceUpstreamError(
+          `${content} (your API token may have expired — try running \`wrangler login\` to obtain a fresh token and restart your dev server)`
+        );
+      }
+
       return new InferenceUpstreamError(content);
     }
   }

src/cloudflare/internal/test/ai/ai-api-test.js

@@ -88,6 +88,39 @@ export const tests = {
       assert.equal(err.message, 'Unknown error');
     }
 
+    {
+      // Test FL2 plain text "error code: 1031" (expired preview token)
+      // includes wrangler login hint. FL2 returns this as text/plain when
+      // the edge preview token has expired during `wrangler dev`.
+      const err = await env.ai._parseError(
+        new Response('error code: 1031', {
+          status: 400,
+          headers: { 'content-type': 'text/plain; charset=UTF-8' },
+        })
+      );
+      assert.equal(err.name, 'InferenceUpstreamError');
+      assert.ok(err.message.includes('1031'), 'should include error code 1031');
+      assert.ok(
+        err.message.includes('wrangler login'),
+        'should suggest running wrangler login'
+      );
+    }
+
+    {
+      // Test error code 1031 via mock (expired preview token model)
+      try {
+        await env.ai.run('expiredTokenModel', { prompt: 'test' });
+        assert.fail('should have thrown');
+      } catch (e) {
+        assert.equal(e.name, 'InferenceUpstreamError');
+        assert.ok(e.message.includes('1031'), 'should include error code 1031');
+        assert.ok(
+          e.message.includes('wrangler login'),
+          'should suggest running wrangler login'
+        );
+      }
+    }
+
     {
       // Test raw input
       const resp = await env.ai.run('rawInputs', { prompt: 'test' });

src/cloudflare/internal/test/ai/ai-mock.js

@@ -126,6 +126,18 @@ export default {
       );
     }
 
+    if (modelName === 'expiredTokenModel') {
+      // Simulate the real FL2 response when an edge preview token has expired.
+      // FL2 returns plain text "error code: 1031" with HTTP 400.
+      return new Response('error code: 1031', {
+        status: 400,
+        headers: {
+          'content-type': 'text/plain; charset=UTF-8',
+          ...respHeaders,
+        },
+      });
+    }
+
     // Handle websocket requests
     if (isWebsocket && modelName === '@cf/test/websocket') {
       // For websocket requests, extract data from URL 'body' parameter