oh-my-openagent/src/features/background-agent/loop-detector.test.ts

import { describe, expect, test } from "bun:test"
import {
  createToolCallSignature,
  detectRepetitiveToolUse,
  recordToolCall,
  resolveCircuitBreakerSettings,
} from "./loop-detector"

function buildWindow(
  toolNames: string[],
  override?: Parameters<typeof resolveCircuitBreakerSettings>[0]
) {
  const settings = resolveCircuitBreakerSettings(override)

  return toolNames.reduce(
    (window, toolName) => recordToolCall(window, toolName, settings),
    undefined as ReturnType<typeof recordToolCall> | undefined
  )
}

function buildWindowWithInputs(
  calls: Array<{ tool: string; input?: Record<string, unknown> }>,
  override?: Parameters<typeof resolveCircuitBreakerSettings>[0]
) {
  const settings = resolveCircuitBreakerSettings(override)
  return calls.reduce(
    (window, { tool, input }) => recordToolCall(window, tool, settings, input),
    undefined as ReturnType<typeof recordToolCall> | undefined
  )
}

describe("loop-detector", () => {
  describe("resolveCircuitBreakerSettings", () => {
    describe("#given nested circuit breaker config", () => {
      test("#when resolved #then nested values override defaults", () => {
        const result = resolveCircuitBreakerSettings({
          maxToolCalls: 200,
          circuitBreaker: {
            maxToolCalls: 120,
            windowSize: 10,
            repetitionThresholdPercent: 70,
          },
        })

        expect(result).toEqual({
          enabled: true,
          maxToolCalls: 120,
          windowSize: 10,
          repetitionThresholdPercent: 70,
        })
      })
    })

    describe("#given no enabled config", () => {
      test("#when resolved #then enabled defaults to true", () => {
        const result = resolveCircuitBreakerSettings({
          circuitBreaker: {
            maxToolCalls: 100,
            windowSize: 5,
            repetitionThresholdPercent: 60,
          },
        })

        expect(result.enabled).toBe(true)
      })
    })

    describe("#given enabled is false in config", () => {
      test("#when resolved #then enabled is false", () => {
        const result = resolveCircuitBreakerSettings({
          circuitBreaker: {
            enabled: false,
            maxToolCalls: 100,
            windowSize: 5,
            repetitionThresholdPercent: 60,
          },
        })

        expect(result.enabled).toBe(false)
      })
    })

    describe("#given enabled is true in config", () => {
      test("#when resolved #then enabled is true", () => {
        const result = resolveCircuitBreakerSettings({
          circuitBreaker: {
            enabled: true,
            maxToolCalls: 100,
            windowSize: 5,
            repetitionThresholdPercent: 60,
          },
        })

        expect(result.enabled).toBe(true)
      })
    })
  })

  describe("createToolCallSignature", () => {
    test("#given tool with input #when signature created #then includes tool and sorted input", () => {
      const result = createToolCallSignature("read", { filePath: "/a.ts" })

      expect(result).toBe('read::{"filePath":"/a.ts"}')
    })

    test("#given tool with undefined input #when signature created #then returns bare tool name", () => {
      const result = createToolCallSignature("read", undefined)

      expect(result).toBe("read")
    })

    test("#given tool with null input #when signature created #then returns bare tool name", () => {
      const result = createToolCallSignature("read", null)

      expect(result).toBe("read")
    })

    test("#given tool with empty object input #when signature created #then returns bare tool name", () => {
      const result = createToolCallSignature("read", {})

      expect(result).toBe("read")
    })

    test("#given same input different key order #when signatures compared #then they are equal", () => {
      const first = createToolCallSignature("read", { filePath: "/a.ts", offset: 0 })
      const second = createToolCallSignature("read", { offset: 0, filePath: "/a.ts" })

      expect(first).toBe(second)
    })
  })

  describe("detectRepetitiveToolUse", () => {
    describe("#given recent tools are diverse", () => {
      test("#when evaluated #then it does not trigger", () => {
        const window = buildWindow([
          "read",
          "grep",
          "edit",
          "bash",
          "read",
          "glob",
          "lsp_diagnostics",
          "read",
          "grep",
          "edit",
        ])

        const result = detectRepetitiveToolUse(window)

        expect(result.triggered).toBe(false)
      })
    })

    describe("#given the same tool dominates the recent window", () => {
      test("#when evaluated #then it triggers", () => {
        const window = buildWindow([
          "read",
          "read",
          "read",
          "edit",
          "read",
          "read",
          "read",
          "read",
          "grep",
          "read",
        ], {
          circuitBreaker: {
            windowSize: 10,
            repetitionThresholdPercent: 80,
          },
        })

        const result = detectRepetitiveToolUse(window)

        expect(result).toEqual({
          triggered: true,
          toolName: "read",
          repeatedCount: 8,
          sampleSize: 10,
          thresholdPercent: 80,
        })
      })
    })

    describe("#given the window is not full yet", () => {
      test("#when the current sample crosses the threshold #then it still triggers", () => {
        const window = buildWindow(["read", "read", "edit", "read", "read", "read", "read", "read"], {
          circuitBreaker: {
            windowSize: 10,
            repetitionThresholdPercent: 80,
          },
        })

        const result = detectRepetitiveToolUse(window)

        expect(result).toEqual({
          triggered: true,
          toolName: "read",
          repeatedCount: 7,
          sampleSize: 8,
          thresholdPercent: 80,
        })
      })
    })

    describe("#given same tool with different file inputs", () => {
      test("#when evaluated #then it does not trigger", () => {
        const calls = Array.from({ length: 20 }, (_, i) => ({
          tool: "read",
          input: { filePath: `/src/file-${i}.ts` },
        }))
        const window = buildWindowWithInputs(calls, {
          circuitBreaker: { windowSize: 20, repetitionThresholdPercent: 80 },
        })
        const result = detectRepetitiveToolUse(window)
        expect(result.triggered).toBe(false)
      })
    })

    describe("#given same tool with identical file inputs", () => {
      test("#when evaluated #then it triggers with bare tool name", () => {
        const calls = [
          ...Array.from({ length: 16 }, () => ({ tool: "read", input: { filePath: "/src/same.ts" } })),
          { tool: "grep", input: { pattern: "foo" } },
          { tool: "edit", input: { filePath: "/src/other.ts" } },
          { tool: "bash", input: { command: "ls" } },
          { tool: "glob", input: { pattern: "**/*.ts" } },
        ]
        const window = buildWindowWithInputs(calls, {
          circuitBreaker: { windowSize: 20, repetitionThresholdPercent: 80 },
        })
        const result = detectRepetitiveToolUse(window)
        expect(result.triggered).toBe(true)
        expect(result.toolName).toBe("read")
        expect(result.repeatedCount).toBe(16)
      })
    })

    describe("#given tool calls with no input", () => {
      test("#when the same tool dominates #then falls back to name-only detection", () => {
        const calls = [
          ...Array.from({ length: 16 }, () => ({ tool: "read" })),
          { tool: "grep" },
          { tool: "edit" },
          { tool: "bash" },
          { tool: "glob" },
        ]
        const window = buildWindowWithInputs(calls, {
          circuitBreaker: { windowSize: 20, repetitionThresholdPercent: 80 },
        })
        const result = detectRepetitiveToolUse(window)
        expect(result.triggered).toBe(true)
        expect(result.toolName).toBe("read")
      })
    })
  })
})