feat(shared): wire tolerantFsync to record skips with path classification

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/shared/tolerant-fsync.test.ts

@@ -1,7 +1,8 @@
-import { describe, expect, it } from "bun:test"
+import { beforeEach, describe, expect, it } from "bun:test"
 import { fsyncSync } from "node:fs"
 import type { FileHandle } from "node:fs/promises"
 
+import { clearAllSkips, drainSkipsAfter } from "./fsync-skip-tracker"
 import { isToleratedFsyncError, tolerantFsync, tolerantFsyncSync } from "./tolerant-fsync"
 
 function makeFsError(code: string, message?: string): NodeJS.ErrnoException {
@@ -60,6 +61,10 @@ describe("isToleratedFsyncError", () => {
 })
 
 describe("tolerantFsync (async)", () => {
+  beforeEach(() => {
+    clearAllSkips()
+  })
+
   it("#given fsync throws EPERM #when called #then resolves without throwing", async () => {
     const handle = fakeHandleWithSyncError(makeFsError("EPERM", "operation not permitted, fsync"))
     await expect(tolerantFsync(handle, "test:async-eperm")).resolves.toBeUndefined()
@@ -100,6 +105,24 @@ describe("tolerantFsync (async)", () => {
     await tolerantFsync(handle, "test:async-success")
     expect(syncCalled).toBe(true)
   })
+
+  it("#given fsync throws EPERM #when called #then tracker records one skip", async () => {
+    const handle = fakeHandleWithSyncError(makeFsError("EPERM", "operation not permitted, fsync"))
+
+    await tolerantFsync(handle, "atomicWrite:/Users/x/Library/Mobile Documents/com~apple~CloudDocs/file.txt")
+
+    const entries = drainSkipsAfter(0)
+    expect(entries).toHaveLength(1)
+    expect(entries[0]?.errorCode).toBe("EPERM")
+  })
+
+  it("#given fsync throws EIO #when called #then tracker remains empty", async () => {
+    const handle = fakeHandleWithSyncError(makeFsError("EIO"))
+
+    await expect(tolerantFsync(handle, "atomicWrite:/tmp/file.txt")).rejects.toThrow("EIO: simulated")
+
+    expect(drainSkipsAfter(0)).toHaveLength(0)
+  })
 })
 
 describe("tolerantFsyncSync (synchronous)", () => {

src/shared/tolerant-fsync.ts

@@ -1,6 +1,8 @@
 import { fsyncSync } from "node:fs"
 import type { FileHandle } from "node:fs/promises"
 
+import { classifyPathEnvironment } from "./classify-path-environment"
+import { recordFsyncSkip } from "./fsync-skip-tracker"
 import { log } from "./logger"
 
 const TOLERATED_FSYNC_CODES: ReadonlySet<string> = new Set([
@@ -16,6 +18,13 @@ export function isToleratedFsyncError(error: unknown): boolean {
   return code !== undefined && TOLERATED_FSYNC_CODES.has(code)
 }
 
+function extractPathFromContextLabel(contextLabel: string): string {
+  const separatorIndex = contextLabel.indexOf(":")
+  if (separatorIndex < 0) return contextLabel
+
+  return contextLabel.slice(separatorIndex + 1)
+}
+
 export async function tolerantFsync(
   fileHandle: FileHandle,
   contextLabel: string,
@@ -24,11 +33,23 @@ export async function tolerantFsync(
     await fileHandle.sync()
   } catch (error) {
     if (!isToleratedFsyncError(error)) throw error
+    const errorCode = (error as NodeJS.ErrnoException).code ?? "UNKNOWN"
+    const message = error instanceof Error ? error.message : String(error)
+    const filePath = extractPathFromContextLabel(contextLabel)
+
     log("fsync skipped due to filesystem limitation", {
       event: "fsync-skipped",
       contextLabel,
-      code: (error as NodeJS.ErrnoException).code,
-      message: error instanceof Error ? error.message : String(error),
+      code: errorCode,
+      message,
+    })
+
+    recordFsyncSkip({
+      filePath,
+      contextLabel,
+      errorCode,
+      message,
+      pathClassification: classifyPathEnvironment(filePath),
     })
   }
 }
@@ -42,11 +63,23 @@ export function tolerantFsyncSync(
     fsyncImpl(fileDescriptor)
   } catch (error) {
     if (!isToleratedFsyncError(error)) throw error
+    const errorCode = (error as NodeJS.ErrnoException).code ?? "UNKNOWN"
+    const message = error instanceof Error ? error.message : String(error)
+    const filePath = extractPathFromContextLabel(contextLabel)
+
     log("fsync skipped due to filesystem limitation", {
       event: "fsync-skipped",
       contextLabel,
-      code: (error as NodeJS.ErrnoException).code,
-      message: error instanceof Error ? error.message : String(error),
+      code: errorCode,
+      message,
+    })
+
+    recordFsyncSkip({
+      filePath,
+      contextLabel,
+      errorCode,
+      message,
+      pathClassification: classifyPathEnvironment(filePath),
     })
   }
 }