test: keep Codecov coverage on real agent communication paths

PR #369 was merged before the final Codecov coverage fix landed, so this follow-up carries only the incremental real-path tests needed on top of main. The tests exercise AgentSummary lifecycle branches, mailbox fail-closed behavior, UDS client connection failure through a real capability file, and UDS response-reader framing without mock.module, warning suppression, feature fallback, or production-code churn.

Constraint: PR #369 is already merged; this branch must contain only the incremental Codecov repair on top of latest main

Rejected: Reopen or keep pushing the merged PR branch | merged PR refs do not update and would leave Codecov stale

Rejected: Mock bun:bundle or hide warnings | would reintroduce cross-test pollution and pseudo coverage

Rejected: Keep unrelated SendMessageTool production diff | it created avoidable patch-coverage debt without improving the runtime path

Confidence: high

Scope-risk: narrow

Directive: Keep these coverage tests on real paths; do not replace them with output suppression or feature-flag mocks

Tested: bunx tsc --noEmit --pretty false

Tested: bun run lint

Tested: bun test src\utils\__tests__\teammateMailbox.test.ts

Tested: bun test src\services\AgentSummary\__tests__\agentSummary.test.ts src\services\AgentSummary\__tests__\summaryContext.test.ts src\utils\__tests__\teammateMailbox.test.ts src\utils\__tests__\udsMessaging.test.ts src\utils\__tests__\udsResponseReader.test.ts packages\builtin-tools\src\tools\SendMessageTool\__tests__\udsRecipientSanitization.test.ts

Tested: bun run test:all

Tested: bun test --coverage --coverage-reporter lcov --coverage-dir coverage

Tested: bun run build

Tested: bun run build:vite

Tested: bun audit

Tested: git diff --check

Tested: Claude simplify review GO (.omx/artifacts/claude-simplify-codecov-20260427-1521.md)

Tested: Claude security review GO (.omx/artifacts/claude-security-codecov-20260427-1522.md)

Not-tested: GitHub-hosted Codecov upload after this amended commit until PR checks rerun

src/services/AgentSummary/__tests__/agentSummary.test.ts

@@ -5,7 +5,10 @@ import type {
   CacheSafeParams,
   ForkedAgentResult,
 } from '../../../utils/forkedAgent.js'
-import { startAgentSummarization } from '../agentSummary.js'
+import {
+  type AgentSummaryDependencies,
+  startAgentSummarization,
+} from '../agentSummary.js'
 
 const transcriptMessages = [
   { type: 'user', message: { content: 'start' }, uuid: 'u1' },
@@ -27,17 +30,14 @@ describe('startAgentSummarization', () => {
   let forkCalls: ForkCall[]
   let updateCalls: Array<{ taskId: string; summary: string }>
   let transcriptMessagesForTest: Message[]
+  let debugLogs: string[]
+  let loggedErrors: Error[]
+  let clearedHandles: unknown[]
 
-  beforeEach(() => {
+  function startTestSummarization(
-    forkCalls = []
+    dependencies: AgentSummaryDependencies = {},
-    updateCalls = []
+  ): { stop: () => void } {
-    scheduled = undefined
+    return startAgentSummarization(
-    handle = undefined
-    transcriptMessagesForTest = transcriptMessages
-  })
-
-  test('summarizes bounded transcript once and skips unchanged fingerprints', async () => {
-    handle = startAgentSummarization(
       'task-1',
       asAgentId('a0000000000000000'),
       {
@@ -48,14 +48,22 @@ describe('startAgentSummarization', () => {
       } as unknown as CacheSafeParams,
       () => undefined,
       {
-        clearTimeout: () => undefined,
+        clearTimeout: ((timeoutId: unknown) => {
+          clearedHandles.push(timeoutId)
+        }) as typeof clearTimeout,
         getAgentTranscript: async () => ({
           messages: transcriptMessagesForTest,
           contentReplacements: [],
         }),
         isPoorModeActive: () => false,
-        logError: () => undefined,
+        logError: error => {
-        logForDebugging: () => undefined,
+          loggedErrors.push(
+            error instanceof Error ? error : new Error(String(error)),
+          )
+        },
+        logForDebugging: message => {
+          debugLogs.push(message)
+        },
         runForkedAgent: async (args: ForkCall) => {
           forkCalls.push(args)
           return {
@@ -79,8 +87,24 @@ describe('startAgentSummarization', () => {
         updateAgentSummary: (taskId: string, summary: string) => {
           updateCalls.push({ taskId, summary })
         },
+        ...dependencies,
       },
     )
+  }
+
+  beforeEach(() => {
+    forkCalls = []
+    updateCalls = []
+    scheduled = undefined
+    handle = undefined
+    transcriptMessagesForTest = transcriptMessages
+    debugLogs = []
+    loggedErrors = []
+    clearedHandles = []
+  })
+
+  test('summarizes bounded transcript once and skips unchanged fingerprints', async () => {
+    handle = startTestSummarization()
 
     expect(typeof scheduled).toBe('function')
     await scheduled!()
@@ -106,47 +130,83 @@ describe('startAgentSummarization', () => {
     expect(updateCalls).toHaveLength(1)
   })
 
-  test('skips summarization when bounded context is too small', async () => {
+  test('skips summarization when filtering leaves too little bounded context', async () => {
-    transcriptMessagesForTest = transcriptMessages.slice(0, 2)
+    transcriptMessagesForTest = [
-
+      { type: 'user', message: { content: 'start' }, uuid: 'u1' },
-    handle = startAgentSummarization(
-      'task-1',
-      asAgentId('a0000000000000000'),
       {
-        forkContextMessages: transcriptMessages,
+        type: 'assistant',
-        model: 'claude-test',
+        uuid: 'a1',
-      } as unknown as CacheSafeParams,
+        message: {
-      () => undefined,
+          content: [{ type: 'tool_use', id: 'missing', name: 'Read' }],
-      {
-        clearTimeout: () => undefined,
-        getAgentTranscript: async () => ({
-          messages: transcriptMessagesForTest,
-          contentReplacements: [],
-        }),
-        isPoorModeActive: () => false,
-        logError: () => undefined,
-        logForDebugging: () => undefined,
-        runForkedAgent: async (args: ForkCall) => {
-          forkCalls.push(args)
-          return { messages: [] } as unknown as ForkedAgentResult
-        },
-        setTimeout: ((callback: TimerHandler) => {
-          if (typeof callback !== 'function') {
-            throw new Error('Expected timer callback')
-          }
-          scheduled = callback as () => void | Promise<void>
-          return 1 as unknown as ReturnType<typeof setTimeout>
-        }) as unknown as typeof setTimeout,
-        updateAgentSummary: (taskId: string, summary: string) => {
-          updateCalls.push({ taskId, summary })
         },
       },
-    )
+      { type: 'user', message: { content: 'continue' }, uuid: 'u2' },
+    ] as unknown as Message[]
+
+    handle = startTestSummarization()
 
     expect(typeof scheduled).toBe('function')
     await scheduled!()
 
     expect(forkCalls).toEqual([])
     expect(updateCalls).toEqual([])
+    expect(debugLogs).toContain(
+      '[AgentSummary] Skipping summary for task-1: no bounded context available',
+    )
+  })
+
+  test('skips summarization before building context when transcript is too short', async () => {
+    transcriptMessagesForTest = transcriptMessages.slice(0, 2)
+    handle = startTestSummarization()
+
+    expect(typeof scheduled).toBe('function')
+    await scheduled!()
+
+    expect(forkCalls).toEqual([])
+    expect(updateCalls).toEqual([])
+    expect(debugLogs).toContain(
+      '[AgentSummary] Skipping summary for task-1: not enough messages (2)',
+    )
+  })
+
+  test('skips and reschedules while poor mode is active', async () => {
+    handle = startTestSummarization({
+      isPoorModeActive: () => true,
+    })
+
+    expect(typeof scheduled).toBe('function')
+    await scheduled!()
+
+    expect(forkCalls).toEqual([])
+    expect(updateCalls).toEqual([])
+    expect(debugLogs).toContain(
+      '[AgentSummary] Skipping summary — poor mode active',
+    )
+  })
+
+  test('logs summary errors and keeps the next timer owned by the summarizer', async () => {
+    const error = new Error('fork failed')
+    handle = startTestSummarization({
+      runForkedAgent: async () => {
+        throw error
+      },
+    })
+
+    expect(typeof scheduled).toBe('function')
+    await scheduled!()
+
+    expect(loggedErrors).toEqual([error])
+    expect(updateCalls).toEqual([])
+  })
+
+  test('stop clears the pending summary timer', () => {
+    handle = startTestSummarization()
+
+    handle.stop()
+
+    expect(debugLogs).toContain(
+      '[AgentSummary] Stopping summarization for task-1',
+    )
+    expect(clearedHandles).toEqual([1])
   })
 })

src/services/AgentSummary/__tests__/summaryContext.test.ts

@@ -141,6 +141,13 @@ describe('getSummaryContextFingerprint', () => {
     expect(estimateMessageChars(message)).toBeGreaterThan(0)
   })
 
+  test('treats unsupported top-level primitives as zero-size estimates', () => {
+    expect(
+      estimateMessageChars((() => undefined) as unknown as Message),
+    ).toBe(0)
+    expect(estimateMessageChars(1n as unknown as Message)).toBe(0)
+  })
+
   test('returns null for an empty transcript', () => {
     expect(getSummaryContextFingerprint([])).toBeNull()
   })

src/utils/__tests__/teammateMailbox.test.ts

@@ -171,6 +171,17 @@ describe('compactMailboxMessages', () => {
 
     expect(compacted).toEqual([])
   })
+
+  test('returns an empty mailbox when all retention lanes are disabled', () => {
+    const compacted = compactMailboxMessages([message('unread', false)], {
+      maxMessages: 0,
+      maxReadMessages: 0,
+      maxUnreadProtocolMessages: 0,
+      maxRetainedBytes: 1_000,
+    })
+
+    expect(compacted).toEqual([])
+  })
 })
 
 describe('teammate mailbox retention', () => {
@@ -331,6 +342,26 @@ describe('teammate mailbox retention', () => {
     expect(await readFile(inboxPath, 'utf-8')).toBe('{not-json')
   })
 
+  test('writeToMailbox rejects when the inbox path is already a directory', async () => {
+    const inboxPath = getInboxPath('worker', 'alpha')
+    await mkdir(inboxPath, { recursive: true })
+
+    const error = await writeToMailbox(
+      'worker',
+      {
+        from: 'team-lead',
+        text: 'new',
+        timestamp: new Date(5).toISOString(),
+      },
+      'alpha',
+    ).then(
+      () => undefined,
+      error => error as NodeJS.ErrnoException,
+    )
+
+    expect(error?.code).toBe('EISDIR')
+  })
+
   test('readMailbox fails closed on corrupt mailbox content', async () => {
     const inboxPath = getInboxPath('worker', 'alpha')
     await mkdir(dirname(inboxPath), { recursive: true })

src/utils/__tests__/udsMessaging.test.ts

@@ -217,6 +217,23 @@ describe('UDS inbox retention', () => {
     )
   })
 
+  test('udsClient send reports connection failures without leaking token state', async () => {
+    const path = socketPath('uds-client-connect-error')
+    const capabilityDir = join(tempConfigDir, 'messaging-capabilities')
+    const capabilityName = `${createHash('sha256').update(path).digest('hex')}.json`
+    await mkdir(capabilityDir, { recursive: true, mode: 0o700 })
+    await writeFile(
+      join(capabilityDir, capabilityName),
+      JSON.stringify({ socketPath: path, authToken: 'test-token' }),
+      'utf-8',
+    )
+    const { sendToUdsSocket } = await import('../udsClient.js')
+
+    await expect(sendToUdsSocket(path, 'hello')).rejects.toThrow(
+      'Failed to connect to peer',
+    )
+  })
+
   test('sendUdsMessage fails closed before connecting without an auth token', async () => {
     await expect(
       sendUdsMessage(socketPath('no-auth-token'), { type: 'text', data: 'x' }),

src/utils/__tests__/udsResponseReader.test.ts

@@ -97,6 +97,28 @@ describe('attachUdsResponseReader', () => {
     expect(socket.ended).toBe(true)
   })
 
+  test('continues scanning when blank and valid frames share one chunk', () => {
+    const socket = new FakeSocket()
+    let settled = false
+    let settledError: Error | undefined
+
+    attachUdsResponseReader(asSocket(socket), {
+      maxFrameBytes: 128,
+      onSettled: error => {
+        settled = true
+        settledError = error
+      },
+    })
+
+    socket.emitData(
+      Buffer.from(`\n${JSON.stringify({ type: 'response' })}\n`),
+    )
+
+    expect(settled).toBe(true)
+    expect(settledError).toBeUndefined()
+    expect(socket.ended).toBe(true)
+  })
+
   test('rejects receiver error frames', () => {
     const socket = new FakeSocket()
     let settledError: Error | undefined
@@ -116,6 +138,31 @@ describe('attachUdsResponseReader', () => {
     expect(socket.destroyed).toBe(true)
   })
 
+  test('ignores unrelated receiver frames until a terminal response arrives', () => {
+    const socket = new FakeSocket()
+    let settled = false
+    let settledError: Error | undefined
+
+    attachUdsResponseReader(asSocket(socket), {
+      maxFrameBytes: 128,
+      onSettled: error => {
+        settled = true
+        settledError = error
+      },
+    })
+
+    socket.emitData(
+      Buffer.from(
+        `${JSON.stringify({ type: 'notification', data: 'queued' })}\n`,
+      ),
+    )
+    expect(settled).toBe(false)
+
+    socket.emitData(Buffer.from(`${JSON.stringify({ type: 'response' })}\n`))
+    expect(settled).toBe(true)
+    expect(settledError).toBeUndefined()
+  })
+
   test('uses custom socket error formatting', () => {
     const socket = new FakeSocket()
     let settledError: Error | undefined