diff --git a/src/modes/detector.ts b/src/modes/detector.ts
index 92d1fed..5b9b7cd 100644
--- a/src/modes/detector.ts
+++ b/src/modes/detector.ts
@@ -44,6 +44,10 @@ export function detectMode(context: GitHubContext): AutoDetectedMode {
 
   // Issue events
   if (isEntityContext(context) && isIssuesEvent(context)) {
+    // If prompt is provided, use agent mode (same as PR events)
+    if (context.inputs.prompt) {
+      return "agent";
+    }
     // Check for @claude mentions or labels/assignees
     if (checkContainsTrigger(context)) {
       return "tag";
diff --git a/tests/modes/detector.test.ts b/tests/modes/detector.test.ts
index 6cbbcb3..39f5d14 100644
--- a/tests/modes/detector.test.ts
+++ b/tests/modes/detector.test.ts
@@ -113,6 +113,33 @@ describe("detectMode with enhanced routing", () => {
 
       expect(detectMode(context)).toBe("agent");
     });
+
+    it("should use agent mode for issues with explicit prompt", () => {
+      const context: GitHubContext = {
+        ...baseContext,
+        eventName: "issues",
+        eventAction: "opened",
+        payload: { issue: { number: 1, body: "Test issue" } } as any,
+        entityNumber: 1,
+        isPR: false,
+        inputs: { ...baseContext.inputs, prompt: "Analyze this issue" },
+      };
+
+      expect(detectMode(context)).toBe("agent");
+    });
+
+    it("should use tag mode for issues with @claude mention and no prompt", () => {
+      const context: GitHubContext = {
+        ...baseContext,
+        eventName: "issues",
+        eventAction: "opened",
+        payload: { issue: { number: 1, body: "@claude help" } } as any,
+        entityNumber: 1,
+        isPR: false,
+      };
+
+      expect(detectMode(context)).toBe("tag");
+    });
   });
 
   describe("Comment Events (unchanged behavior)", () => {