fix(circuit-breaker): wire target-aware detection into background manager

src/features/background-agent/manager-circuit-breaker.test.ts

@@ -236,4 +236,181 @@ describe("BackgroundManager circuit breaker", () => {
       expect(task.progress?.countedToolPartIDs).toEqual(["tool-1"])
     })
   })
+
+  describe("#given same tool reading different files", () => {
+    test("#when tool events arrive with state.input #then task keeps running", async () => {
+      const manager = createManager({
+        circuitBreaker: {
+          windowSize: 20,
+          repetitionThresholdPercent: 80,
+        },
+      })
+      const task: BackgroundTask = {
+        id: "task-diff-files-1",
+        sessionID: "session-diff-files-1",
+        parentSessionID: "parent-1",
+        parentMessageID: "msg-1",
+        description: "Reading different files",
+        prompt: "work",
+        agent: "explore",
+        status: "running",
+        startedAt: new Date(Date.now() - 60_000),
+        progress: {
+          toolCalls: 0,
+          lastUpdate: new Date(Date.now() - 60_000),
+        },
+      }
+      getTaskMap(manager).set(task.id, task)
+
+      for (let i = 0; i < 20; i++) {
+        manager.handleEvent({
+          type: "message.part.updated",
+          properties: {
+            part: {
+              sessionID: task.sessionID,
+              type: "tool",
+              tool: "read",
+              state: { status: "running", input: { filePath: `/src/file-${i}.ts` } },
+            },
+          },
+        })
+      }
+
+      await flushAsyncWork()
+
+      expect(task.status).toBe("running")
+      expect(task.progress?.toolCalls).toBe(20)
+    })
+  })
+
+  describe("#given same tool reading same file repeatedly", () => {
+    test("#when tool events arrive with state.input #then task is cancelled with bare tool name in error", async () => {
+      const manager = createManager({
+        circuitBreaker: {
+          windowSize: 20,
+          repetitionThresholdPercent: 80,
+        },
+      })
+      const task: BackgroundTask = {
+        id: "task-same-file-1",
+        sessionID: "session-same-file-1",
+        parentSessionID: "parent-1",
+        parentMessageID: "msg-1",
+        description: "Reading same file repeatedly",
+        prompt: "work",
+        agent: "explore",
+        status: "running",
+        startedAt: new Date(Date.now() - 60_000),
+        progress: {
+          toolCalls: 0,
+          lastUpdate: new Date(Date.now() - 60_000),
+        },
+      }
+      getTaskMap(manager).set(task.id, task)
+
+      for (let i = 0; i < 20; i++) {
+        manager.handleEvent({
+          type: "message.part.updated",
+          properties: {
+            part: {
+              sessionID: task.sessionID,
+              type: "tool",
+              tool: "read",
+              state: { status: "running", input: { filePath: "/src/same.ts" } },
+            },
+          },
+        })
+      }
+
+      await flushAsyncWork()
+
+      expect(task.status).toBe("cancelled")
+      expect(task.error).toContain("repeatedly called read")
+      expect(task.error).not.toContain("::")
+    })
+  })
+
+  describe("#given circuit breaker enabled is false", () => {
+    test("#when repetitive tools arrive #then task keeps running", async () => {
+      const manager = createManager({
+        circuitBreaker: {
+          enabled: false,
+          windowSize: 20,
+          repetitionThresholdPercent: 80,
+        },
+      })
+      const task: BackgroundTask = {
+        id: "task-disabled-1",
+        sessionID: "session-disabled-1",
+        parentSessionID: "parent-1",
+        parentMessageID: "msg-1",
+        description: "Disabled circuit breaker task",
+        prompt: "work",
+        agent: "explore",
+        status: "running",
+        startedAt: new Date(Date.now() - 60_000),
+        progress: {
+          toolCalls: 0,
+          lastUpdate: new Date(Date.now() - 60_000),
+        },
+      }
+      getTaskMap(manager).set(task.id, task)
+
+      for (let i = 0; i < 20; i++) {
+        manager.handleEvent({
+          type: "message.part.updated",
+          properties: {
+            sessionID: task.sessionID,
+            type: "tool",
+            tool: "read",
+          },
+        })
+      }
+
+      await flushAsyncWork()
+
+      expect(task.status).toBe("running")
+    })
+  })
+
+  describe("#given circuit breaker enabled is false but absolute cap is low", () => {
+    test("#when max tool calls exceeded #then task is still cancelled by absolute cap", async () => {
+      const manager = createManager({
+        maxToolCalls: 3,
+        circuitBreaker: {
+          enabled: false,
+          windowSize: 10,
+          repetitionThresholdPercent: 95,
+        },
+      })
+      const task: BackgroundTask = {
+        id: "task-cap-disabled-1",
+        sessionID: "session-cap-disabled-1",
+        parentSessionID: "parent-1",
+        parentMessageID: "msg-1",
+        description: "Backstop task with disabled circuit breaker",
+        prompt: "work",
+        agent: "explore",
+        status: "running",
+        startedAt: new Date(Date.now() - 60_000),
+        progress: {
+          toolCalls: 0,
+          lastUpdate: new Date(Date.now() - 60_000),
+        },
+      }
+      getTaskMap(manager).set(task.id, task)
+
+      for (const toolName of ["read", "grep", "edit"]) {
+        manager.handleEvent({
+          type: "message.part.updated",
+          properties: { sessionID: task.sessionID, type: "tool", tool: toolName },
+        })
+      }
+
+      await flushAsyncWork()
+
+      expect(task.status).toBe("cancelled")
+      expect(task.error).toContain("maximum tool call limit (3)")
+    })
+  })
 })

src/features/background-agent/manager.ts

@@ -74,7 +74,7 @@ interface MessagePartInfo {
   sessionID?: string
   type?: string
   tool?: string
-  state?: { status?: string }
+  state?: { status?: string; input?: Record<string, unknown> }
 }
 
 interface EventProperties {
@@ -918,29 +918,32 @@ export class BackgroundManager {
         task.progress.lastTool = partInfo.tool
         const circuitBreaker = resolveCircuitBreakerSettings(this.config)
         if (partInfo.tool) {
-          task.progress.toolCallWindow = recordToolCall(
-            task.progress.toolCallWindow,
-            partInfo.tool,
-            circuitBreaker
-          )
+         task.progress.toolCallWindow = recordToolCall(
+             task.progress.toolCallWindow,
+             partInfo.tool,
+             circuitBreaker,
+             partInfo.state?.input
+           )
 
-          const loopDetection = detectRepetitiveToolUse(task.progress.toolCallWindow)
-          if (loopDetection.triggered) {
-            log("[background-agent] Circuit breaker: repetitive tool usage detected", {
-              taskId: task.id,
-              agent: task.agent,
-              sessionID,
-              toolName: loopDetection.toolName,
-              repeatedCount: loopDetection.repeatedCount,
-              sampleSize: loopDetection.sampleSize,
-              thresholdPercent: loopDetection.thresholdPercent,
-            })
-            void this.cancelTask(task.id, {
-              source: "circuit-breaker",
-              reason: `Subagent repeatedly called ${loopDetection.toolName} ${loopDetection.repeatedCount}/${loopDetection.sampleSize} times in the recent tool-call window (${loopDetection.thresholdPercent}% threshold). This usually indicates an infinite loop. The task was automatically cancelled to prevent excessive token usage.`,
-            })
-            return
-          }
+           if (circuitBreaker.enabled) {
+             const loopDetection = detectRepetitiveToolUse(task.progress.toolCallWindow)
+             if (loopDetection.triggered) {
+               log("[background-agent] Circuit breaker: repetitive tool usage detected", {
+                 taskId: task.id,
+                 agent: task.agent,
+                 sessionID,
+                 toolName: loopDetection.toolName,
+                 repeatedCount: loopDetection.repeatedCount,
+                 sampleSize: loopDetection.sampleSize,
+                 thresholdPercent: loopDetection.thresholdPercent,
+               })
+               void this.cancelTask(task.id, {
+                 source: "circuit-breaker",
+                 reason: `Subagent repeatedly called ${loopDetection.toolName} ${loopDetection.repeatedCount}/${loopDetection.sampleSize} times in the recent tool-call window (${loopDetection.thresholdPercent}% threshold). This usually indicates an infinite loop. The task was automatically cancelled to prevent excessive token usage.`,
+               })
+               return
+             }
+           }
         }
 
         const maxToolCalls = circuitBreaker.maxToolCalls