fix: retry AI fallback once on HTTP 429 with Retry-After backoff

When the GitHub Models API rate-limits the backfill (429), read the
Retry-After header (capped at 60s), wait, then retry the request once.
If the retry also fails the issue is skipped as before.

Author: dgibbs64

.github/workflows/labeler.yml

@@ -1337,37 +1337,40 @@ jobs:
                 // Optional AI fallback for legacy issues where deterministic matching finds nothing.
                 if (useAiGameFallback && desiredGames.size === 0) {
                   aiGameAttempts += 1;
-                  try {
-                    const res = await fetch(
-                      `https://models.github.ai/orgs/${owner}/inference/chat/completions`,
+                  const aiPayload = {
+                    model: 'openai/gpt-4.1-mini',
+                    temperature: 0.1,
+                    max_tokens: 120,
+                    messages: [
                       {
-                        method: 'POST',
-                        headers: {
-                          Accept: 'application/vnd.github+json',
-                          Authorization: `Bearer ${process.env.GITHUB_TOKEN}`,
-                          'X-GitHub-Api-Version': '2026-03-10',
-                          'Content-Type': 'application/json',
-                        },
-                        body: JSON.stringify({
-                          model: 'openai/gpt-4.1-mini',
-                          temperature: 0.1,
-                          max_tokens: 120,
-                          messages: [
-                            {
-                              role: 'system',
-                              content:
-                                'Return JSON only. Identify the game referenced in this LinuxGSM issue with high precision.',
-                            },
-                            {
-                              role: 'user',
-                              content:
-                                `Title: ${title}\n\nBody:\n${body.slice(0, 2500)}\n\n` +
-                                'Return JSON: {"detected_game":"string or null","game_confidence":"high|medium|low|null"}',
-                            },
-                          ],
-                        }),
-                      }
-                    );
+                        role: 'system',
+                        content: 'Return JSON only. Identify the game referenced in this LinuxGSM issue with high precision.',
+                      },
+                      {
+                        role: 'user',
+                        content:
+                          `Title: ${title}\n\nBody:\n${body.slice(0, 2500)}\n\n` +
+                          'Return JSON: {"detected_game":"string or null","game_confidence":"high|medium|low|null"}',
+                      },
+                    ],
+                  };
+                  const aiUrl = `https://models.github.ai/orgs/${owner}/inference/chat/completions`;
+                  const aiHeaders = {
+                    Accept: 'application/vnd.github+json',
+                    Authorization: `Bearer ${process.env.GITHUB_TOKEN}`,
+                    'X-GitHub-Api-Version': '2026-03-10',
+                    'Content-Type': 'application/json',
+                  };
+                  try {
+                    let res = await fetch(aiUrl, { method: 'POST', headers: aiHeaders, body: JSON.stringify(aiPayload) });
+
+                    // On 429 honour Retry-After (capped at 60 s) then retry once.
+                    if (res.status === 429) {
+                      const retryAfter = Math.min(Number.parseInt(res.headers.get('Retry-After') || '10', 10), 60);
+                      console.log(`#${rawIssue.number}: AI fallback rate-limited — waiting ${retryAfter}s then retrying…`);
+                      await new Promise((r) => setTimeout(r, retryAfter * 1000));
+                      res = await fetch(aiUrl, { method: 'POST', headers: aiHeaders, body: JSON.stringify(aiPayload) });
+                    }
 
                     if (res.ok) {
                       const data = await res.json();