Handle missing reviewer LLM credentials

agent.py

@@ -69,6 +69,18 @@ class AgentReviewer(A2AAgent[ReviewerConfig, NoAuth]):
         if not ctx.cp_jwt or not ctx.cp_url:
             return {"error": "no cp_jwt; this agent must run through the orchestrator"}
 
+        creds = ctx.llm
+        if not creds.api_key:
+            return {
+                "error": "llm_credentials_missing",
+                "final": (
+                    "LLM credentials were not available for this review. "
+                    "Hosted reviewer runs should receive a platform LLM grant."
+                ),
+                "agent_name": agent_name,
+                "ref": ref,
+            }
+
         await ctx.emit_progress(f"requesting read-only Gitea token for {agent_name}@{ref}")
         try:
             mint = await ctx.mint_gitea_token(
@@ -88,7 +100,6 @@ class AgentReviewer(A2AAgent[ReviewerConfig, NoAuth]):
             f"minted token {token_name} (read on {gitea_owner}/{agent_name})"
         )
 
-        creds = ctx.llm
         await ctx.emit_progress(f"llm: {creds.model} via {creds.source}")
 
         completion_box: dict[str, ReviewReport] = {}