fix(hooks): add null guard for tool.execute.after output (#1054)

/review command and some Claude Code built-in commands trigger
tool.execute.after hooks with undefined output, causing crashes
when accessing output.metadata or output.output.

Fixes #1035

Co-authored-by: sisyphus-dev-ai <sisyphus-dev-ai@users.noreply.github.com>

src/hooks/atlas/index.test.ts

@@ -66,6 +66,20 @@ describe("atlas hook", () => {
   })
 
   describe("tool.execute.after handler", () => {
+    test("should handle undefined output gracefully (issue #1035)", async () => {
+      // #given - hook and undefined output (e.g., from /review command)
+      const hook = createAtlasHook(createMockPluginInput())
+
+      // #when - calling with undefined output
+      const result = await hook["tool.execute.after"](
+        { tool: "delegate_task", sessionID: "session-123" },
+        undefined as unknown as { title: string; output: string; metadata: Record<string, unknown> }
+      )
+
+      // #then - returns undefined without throwing
+      expect(result).toBeUndefined()
+    })
+
     test("should ignore non-delegate_task tools", async () => {
       // #given - hook and non-delegate_task tool
       const hook = createAtlasHook(createMockPluginInput())

src/hooks/atlas/index.ts

@@ -663,6 +663,11 @@ export function createAtlasHook(
       input: ToolExecuteAfterInput,
       output: ToolExecuteAfterOutput
     ): Promise<void> => {
+      // Guard against undefined output (e.g., from /review command - see issue #1035)
+      if (!output) {
+        return
+      }
+
       if (!isCallerOrchestrator(input.sessionID)) {
         return
       }