Fetch GitHub Models catalog with httpx and documented headers

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

artifacts/flask-api/ai_agent.py

@@ -8,6 +8,7 @@ Supporte Mistral AI (par défaut) et tout fournisseur compatible OpenAI.
 import json
 import os
 import logging
+import httpx
 from openai import OpenAI, BadRequestError
 from legal_framework import LEGAL_FILTER_PROMPT, SYNTHESIS_PROMPT, LAW_CHECK_PROMPT, build_filter_prompt
 from legifrance_client import get_legifrance_client
@@ -84,9 +85,18 @@ def list_model_ids() -> list[str]:
     """Modèles accessibles avec la clé en place (GitHub Models : catalogue dédié, /models n'est pas OpenAI-compatible)."""
     client = get_client()
     if "models.github.ai" in str(client.base_url):
-        raw = client.get(GITHUB_CATALOG_URL, cast_to=object)
-        if isinstance(raw, (str, bytes)):  # content-type non-JSON : le SDK rend le texte brut
-            raw = json.loads(raw)
+        r = httpx.get(
+            GITHUB_CATALOG_URL,
+            headers={
+                "Authorization": f"Bearer {client.api_key}",
+                "Accept": "application/vnd.github+json",
+                "X-GitHub-Api-Version": "2022-11-28",
+            },
+            timeout=10,
+        )
+        if r.status_code != 200 or not r.content:
+            raise RuntimeError(f"catalogue GitHub HTTP {r.status_code} : {r.text[:120]!r}")
+        raw = r.json()
         if isinstance(raw, dict):
             raw = next((v for v in raw.values() if isinstance(v, list)), [])
         return sorted(m["id"] if isinstance(m, dict) else str(m) for m in raw)