Merge pull request #3348 from code-yeongyu/refactor/ulw-repo-cleanup-20260411

refactor: simplify nullish guards and remove dead no-op paths

src/features/background-agent/loop-detector.test.ts

@@ -112,6 +112,20 @@ describe("loop-detector", () => {
       expect(result).toBe("read")
     })
 
+    test("#given nullish inputs #when signatures are created #then null and undefined behave the same", () => {
+      // given
+      const undefinedInput = undefined
+      const nullInput = null
+
+      // when
+      const undefinedResult = createToolCallSignature("read", undefinedInput)
+      const nullResult = createToolCallSignature("read", nullInput)
+
+      // then
+      expect(undefinedResult).toBe("read")
+      expect(nullResult).toBe(undefinedResult)
+    })
+
     test("#given tool with empty object input #when signature created #then returns bare tool name", () => {
       const result = createToolCallSignature("read", {})
 
@@ -259,5 +273,24 @@ describe("loop-detector", () => {
         expect(result).toEqual({ triggered: false })
       })
     })
+
+    describe("#given nullish tool inputs", () => {
+      test("#when recorded #then null and undefined produce the same unknown-input window", () => {
+        // given
+        const settings = resolveCircuitBreakerSettings()
+
+        // when
+        const undefinedWindow = recordToolCall(undefined, "read", settings, undefined)
+        const nullWindow = recordToolCall(undefined, "read", settings, null)
+
+        // then
+        expect(undefinedWindow).toEqual(nullWindow)
+        expect(undefinedWindow).toEqual({
+          lastSignature: "read::__unknown-input__",
+          consecutiveCount: 1,
+          threshold: settings.consecutiveThreshold,
+        })
+      })
+    })
   })
 })

src/features/background-agent/loop-detector.ts

@@ -36,7 +36,7 @@ export function recordToolCall(
   settings: CircuitBreakerSettings,
   toolInput?: Record<string, unknown> | null
 ): ToolCallWindow {
-  if (toolInput === undefined || toolInput === null) {
+  if (toolInput == null) {
     return {
       lastSignature: `${toolName}::__unknown-input__`,
       consecutiveCount: 1,
@@ -62,7 +62,7 @@ export function recordToolCall(
 }
 
 function sortObject(obj: unknown): unknown {
-  if (obj === null || obj === undefined) return obj
+  if (obj == null) return obj
   if (typeof obj !== "object") return obj
   if (Array.isArray(obj)) return obj.map(sortObject)
 
@@ -78,7 +78,7 @@ export function createToolCallSignature(
   toolName: string,
   toolInput?: Record<string, unknown> | null
 ): string {
-  if (toolInput === undefined || toolInput === null) {
+  if (toolInput == null) {
     return toolName
   }
   if (Object.keys(toolInput).length === 0) {