diff --git a/gitnexus/src/core/lbug/sidecar-recovery.ts b/gitnexus/src/core/lbug/sidecar-recovery.ts
index f9e86719d..b34b4d905 100644
--- a/gitnexus/src/core/lbug/sidecar-recovery.ts
+++ b/gitnexus/src/core/lbug/sidecar-recovery.ts
@@ -113,7 +113,9 @@ const warnOnce = (logger: SidecarRecoveryLogger, key: string, message: string):
 // — `git grep "LADYBUGDB-CONTRACT"` enumerates every version-coupled spot.
 export const isMissingShadowSidecarError = (err: unknown): boolean => {
   const msg = err instanceof Error ? err.message : String(err);
-  return /Cannot open file .*\.shadow: No such file or directory/i.test(msg);
+  return /Cannot open file(?:\. path:)? .*\.shadow(?:: No such file or directory| - Error 2: The system cannot find the file specified\.?)/i.test(
+    msg,
+  );
 };
 
 // LADYBUGDB-CONTRACT: matches @ladybugdb/core ^0.16.1 native error text.
diff --git a/gitnexus/test/unit/sidecar-recovery.test.ts b/gitnexus/test/unit/sidecar-recovery.test.ts
index c0a2c4752..ce550c90f 100644
--- a/gitnexus/test/unit/sidecar-recovery.test.ts
+++ b/gitnexus/test/unit/sidecar-recovery.test.ts
@@ -7,6 +7,7 @@ import {
   _resetSidecarRecoveryWarningsForTest,
   finalizeLbugSidecarsAfterClose,
   inspectLbugSidecars,
+  isMissingShadowSidecarError,
   isPermissionRenameError,
   isReadOnlyShadowReplayError,
   listQuarantinedMissingShadowWals,
@@ -184,6 +185,24 @@ describe('LadybugDB sidecar recovery', () => {
   });
 
   describe('Centralized isReadOnlyShadowReplayError (PR #1747 review, F4 dedup)', () => {
+    it('matches LadybugDB missing-shadow errors on both Unix and Windows formats', () => {
+      const unixErr = new Error(
+        'IO exception: Cannot open file /tmp/lbug.shadow: No such file or directory',
+      );
+      const winErr = new Error(
+        'IO exception: Cannot open file. path: D:\\repo\\.gitnexus\\lbug.shadow - Error 2: The system cannot find the file specified.',
+      );
+      expect(isMissingShadowSidecarError(unixErr)).toBe(true);
+      expect(isMissingShadowSidecarError(winErr)).toBe(true);
+    });
+
+    it('false-positive guard: missing-shadow matcher rejects unrelated errors', () => {
+      expect(isMissingShadowSidecarError(new Error('file not found'))).toBe(false);
+      expect(
+        isMissingShadowSidecarError(new Error('Cannot open file /tmp/lbug.wal: lock conflict')),
+      ).toBe(false);
+    });
+
     it('matches LadybugDB read-only shadow-replay error', () => {
       const err = new Error(
         "Runtime exception: Couldn't replay shadow pages under read-only mode. Please re-open the database with read-write mode to replay shadow pages.",