diff --git a/frontend/src/features/agents/hooks/useAgentDrillDown.js b/frontend/src/features/agents/hooks/useAgentDrillDown.js
index 46474d0..a3dca03 100644
--- a/frontend/src/features/agents/hooks/useAgentDrillDown.js
+++ b/frontend/src/features/agents/hooks/useAgentDrillDown.js
@@ -1,4 +1,4 @@
-import { useState, useEffect, useCallback } from 'react';
+import { useState, useEffect, useCallback, useRef } from 'react';
 import { 
     getAgents, 
     getSessionMessages, 
@@ -145,51 +145,14 @@
                 setTriggers(tList);
             } catch(e) {}
 
-            const sid = found.session?.sync_workspace_id || found.session_id;
-            const nodeId = found.mesh_node_id || "hub";
-            
-            if (sid) {
-                try {
-                    const cFilesListing = await getAgentCortexFiles(agentId, nodeId, sid);
-                    const files = cFilesListing.files || [];
-                    setCortexFiles(files);
-
-                    const fileExists = (name) => files.some(f => f.name === name || f.path === `.cortex/${name}`);
-
-                    if (fileExists("feedback.md")) {
-                        try {
-                            const feedback = await getAgentCortexFile(agentId, nodeId, sid, "feedback.md");
-                            setFeedbackContent(feedback?.content || "");
-                        } catch (e) {}
-                    }
-
-                    if (fileExists("rubric.md")) {
-                        try {
-                            const rubric = await getAgentCortexFile(agentId, nodeId, sid, "rubric.md");
-                            setRubricContent(rubric?.content || "");
-                        } catch (e) {}
-                    }
-
-                    try {
-                        const coworker = await getAgentCortexFile(agentId, nodeId, sid, ".coworker.md");
-                        setCoworkerContent(coworker?.content || "");
-                    } catch (e) {}
-
-                    if (fileExists("history.log")) {
-                        try {
-                            const logs = await getAgentCortexFile(agentId, nodeId, sid, "history.log");
-                            if (logs?.content) {
-                                try {
-                                    const parsed = JSON.parse(logs.content);
-                                    setHistoryLog(Array.isArray(parsed) ? parsed : []);
-                                } catch (e) {
-                                    setHistoryLog(logs.content.split('\n').filter(l => l.trim()).map(line => ({ message: line })));
-                                }
-                            }
-                        } catch (e) {}
-                    }
-                } catch (e) {}
+            // Cortex files (feedback, rubric, history) are fetched separately
+            // only when agent transitions to idle, to avoid blocking gRPC during active runs.
+            const isActive = found.status === 'active' || found.status === 'starting';
+            const wasActive = prevStatusRef.current === 'active' || prevStatusRef.current === 'starting';
+            if (!isActive && (wasActive || prevStatusRef.current === null)) {
+                fetchCortexFiles(found);
             }
+            prevStatusRef.current = found.status;
         } catch (err) {
             setError(err.message);
         } finally {
@@ -229,6 +192,56 @@
         loadConf();
     }, []);
 
+    // Separate cortex file fetch so blocking gRPC calls don't run every 2.5s
+    const fetchCortexFiles = useCallback(async (found) => {
+        const sid = found.session?.sync_workspace_id || found.session_id;
+        const nodeId = found.mesh_node_id || "hub";
+        if (!sid) return;
+        try {
+            const cFilesListing = await getAgentCortexFiles(agentId, nodeId, sid);
+            const files = cFilesListing.files || [];
+            setCortexFiles(files);
+
+            const fileExists = (name) => files.some(f => f.name === name || f.path === `.cortex/${name}`);
+
+            if (fileExists("feedback.md")) {
+                try {
+                    const feedback = await getAgentCortexFile(agentId, nodeId, sid, "feedback.md");
+                    setFeedbackContent(feedback?.content || "");
+                } catch (e) {}
+            }
+
+            if (fileExists("rubric.md")) {
+                try {
+                    const rubric = await getAgentCortexFile(agentId, nodeId, sid, "rubric.md");
+                    setRubricContent(rubric?.content || "");
+                } catch (e) {}
+            }
+
+            try {
+                const coworker = await getAgentCortexFile(agentId, nodeId, sid, ".coworker.md");
+                setCoworkerContent(coworker?.content || "");
+            } catch (e) {}
+
+            if (fileExists("history.log")) {
+                try {
+                    const logs = await getAgentCortexFile(agentId, nodeId, sid, "history.log");
+                    if (logs?.content) {
+                        try {
+                            const parsed = JSON.parse(logs.content);
+                            setHistoryLog(Array.isArray(parsed) ? parsed : []);
+                        } catch (e) {
+                            setHistoryLog(logs.content.split('\n').filter(l => l.trim()).map(line => ({ message: line })));
+                        }
+                    }
+                } catch (e) {}
+            }
+        } catch (e) {}
+    }, [agentId]);
+
+    // Track previous status to detect transitions to idle
+    const prevStatusRef = useRef(null);
+
     useEffect(() => {
         fetchData();
         const interval = setInterval(fetchData, 2500);