test: keep review assertions tied to real failure paths

CodeRabbit flagged three non-blocking but valid review gaps: platform-specific mailbox errno checks, brittle UDS connection-failure message assertions, and missing AgentSummary reschedule proof after fork errors. This keeps the fixes narrow by tightening the affected assertions and adding a structured UDS connection error for tests to assert behavior instead of prose.

Constraint: PR #374 is a review follow-up and must not hide warnings, skip tests, or merge the PR.

Rejected: Matching the UDS failure message literal | preserves the brittle coupling CodeRabbit flagged.

Rejected: Asserting only that mailbox writes throw | would allow unrelated pre-path failures to pass.

Confidence: high

Scope-risk: narrow

Directive: Keep UDS connection-failure tests on structured error data, not display wording.

Tested: bun test src/services/AgentSummary/__tests__/agentSummary.test.ts src/utils/__tests__/teammateMailbox.test.ts src/utils/__tests__/udsMessaging.test.ts

Tested: bunx tsc --noEmit --pretty false

Tested: bun run lint

Tested: bun run test:all

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

Tested: bun run build

Tested: bun run build:vite

Not-tested: GitHub-hosted CodeRabbit refresh until pushed.

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

@@ -33,6 +33,7 @@ describe('startAgentSummarization', () => {
   let debugLogs: string[]
   let loggedErrors: Error[]
   let clearedHandles: unknown[]
+  let scheduledCount: number
 
   function startTestSummarization(
     dependencies: AgentSummaryDependencies = {},
@@ -81,8 +82,9 @@ describe('startAgentSummarization', () => {
           if (typeof callback !== 'function') {
             throw new Error('Expected timer callback')
           }
+          scheduledCount += 1
           scheduled = callback as () => void | Promise<void>
-          return 1 as unknown as ReturnType<typeof setTimeout>
+          return scheduledCount as unknown as ReturnType<typeof setTimeout>
         }) as unknown as typeof setTimeout,
         updateAgentSummary: (taskId: string, summary: string) => {
           updateCalls.push({ taskId, summary })
@@ -101,6 +103,7 @@ describe('startAgentSummarization', () => {
     debugLogs = []
     loggedErrors = []
     clearedHandles = []
+    scheduledCount = 0
   })
 
   test('summarizes bounded transcript once and skips unchanged fingerprints', async () => {
@@ -175,6 +178,7 @@ describe('startAgentSummarization', () => {
     })
 
     expect(typeof scheduled).toBe('function')
+    const initialScheduledCount = scheduledCount
     await scheduled!()
 
     expect(forkCalls).toEqual([])
@@ -182,6 +186,7 @@ describe('startAgentSummarization', () => {
     expect(debugLogs).toContain(
       '[AgentSummary] Skipping summary — poor mode active',
     )
+    expect(scheduledCount).toBe(initialScheduledCount + 1)
   })
 
   test('logs summary errors and keeps the next timer owned by the summarizer', async () => {
@@ -193,10 +198,12 @@ describe('startAgentSummarization', () => {
     })
 
     expect(typeof scheduled).toBe('function')
+    const initialScheduledCount = scheduledCount
     await scheduled!()
 
     expect(loggedErrors).toEqual([error])
     expect(updateCalls).toEqual([])
+    expect(scheduledCount).toBe(initialScheduledCount + 1)
   })
 
   test('stop clears the pending summary timer', () => {

src/utils/__tests__/teammateMailbox.test.ts

@@ -1,9 +1,10 @@
 import { afterEach, beforeEach, describe, expect, test } from 'bun:test'
-import { mkdir, readFile, rm, writeFile } from 'node:fs/promises'
+import { mkdir, readFile, rm, stat, writeFile } from 'node:fs/promises'
 import { mkdtempSync } from 'node:fs'
 import { tmpdir } from 'node:os'
 import { dirname, join } from 'node:path'
 import type { Message } from 'src/types/message.js'
+import { getErrnoCode } from 'src/utils/errors.js'
 import {
   compactMailboxMessages,
   getLastPeerDmSummary,
@@ -356,10 +357,16 @@ describe('teammate mailbox retention', () => {
       'alpha',
     ).then(
       () => undefined,
-      error => error as NodeJS.ErrnoException,
+      err => err,
     )
 
-    expect(error?.code).toBe('EISDIR')
+    const code = getErrnoCode(error)
+    expect(code).toBeDefined()
+    if (code === undefined) {
+      throw new Error('Expected filesystem errno code')
+    }
+    expect(['EISDIR', 'EPERM', 'EACCES']).toContain(code)
+    expect((await stat(inboxPath)).isDirectory()).toBe(true)
   })
 
   test('readMailbox fails closed on corrupt mailbox content', async () => {

src/utils/__tests__/udsMessaging.test.ts

@@ -227,11 +227,20 @@ describe('UDS inbox retention', () => {
       JSON.stringify({ socketPath: path, authToken: 'test-token' }),
       'utf-8',
     )
-    const { sendToUdsSocket } = await import('../udsClient.js')
+    const { sendToUdsSocket, UdsPeerConnectionError } = await import(
-
+      '../udsClient.js'
-    await expect(sendToUdsSocket(path, 'hello')).rejects.toThrow(
-      'Failed to connect to peer',
     )
+
+    const error = await sendToUdsSocket(path, 'hello').then(
+      () => undefined,
+      err => err,
+    )
+    expect(error).toBeInstanceOf(UdsPeerConnectionError)
+    if (!(error instanceof UdsPeerConnectionError)) {
+      throw new Error('Expected UDS peer connection error')
+    }
+    expect(error.socketPath).toBe(path)
+    expect(error.message).not.toContain('test-token')
   })
 
   test('sendUdsMessage fails closed before connecting without an auth token', async () => {

src/utils/udsClient.ts

@@ -36,6 +36,18 @@ export type PeerSession = {
   alive: boolean
 }
 
+export class UdsPeerConnectionError extends Error {
+  readonly socketPath: string
+  readonly cause: unknown
+
+  constructor(socketPath: string, cause: unknown) {
+    super(`Failed to connect to peer at ${socketPath}: ${errorMessage(cause)}`)
+    this.name = 'UdsPeerConnectionError'
+    this.socketPath = socketPath
+    this.cause = cause
+  }
+}
+
 // ---------------------------------------------------------------------------
 // Session directory
 // ---------------------------------------------------------------------------
@@ -237,9 +249,7 @@ export async function sendToUdsSocket(
       maxFrameBytes: MAX_UDS_FRAME_BYTES,
       onSettled: finish,
       formatSocketError: err =>
-        new Error(
+        new UdsPeerConnectionError(target.socketPath, err),
-          `Failed to connect to peer at ${target.socketPath}: ${errorMessage(err)}`,
-        ),
     })
     conn.setTimeout(5000, () => {
       finish(new Error('Connection timed out'))