diff --git a/tools/path-normalization.mjs b/tools/path-normalization.mjs
index 97f8bc234..1be3c5f64 100644
--- a/tools/path-normalization.mjs
+++ b/tools/path-normalization.mjs
@@ -94,5 +94,8 @@ export function pathNormalize(target, opts = {}) {
     if (e && e.code && e.code !== 'ENOENT') throw e; // surface real FS errors; fail-close handled by caller
     real = resolved; // ENOENT — best-effort resolved path for unknown-state files
   }
-  return caseFold(real, platform);
+  // Smoke 5 integration fix (2026-05-30): normalize ALL separators to forward slashes
+  // regardless of platform. DEFAULT_PROTECTED_PATTERNS regexes are forward-slash only.
+  // Without this, win32 path.resolve + realpath returns backslashes and patterns miss.
+  return caseFold(real, platform).split('\\').join('/');
 }
diff --git a/tools/path-normalization.test.mjs b/tools/path-normalization.test.mjs
index b6c77d6a7..2a9611812 100644
--- a/tools/path-normalization.test.mjs
+++ b/tools/path-normalization.test.mjs
@@ -78,6 +78,20 @@ describe('pathNormalize', () => {
   it('expands ~ and resolves', () => {
     expect(pathNormalize('~/x', { homedir: '/h', realpath: (p) => p, resolve: (p) => p, platform: 'linux', env: {} })).toBe('/h/x');
   });
+  // Smoke 5 integration bug 2026-05-30 — Stream A pathNormalize returned backslashes
+  // on win32, breaking DEFAULT_PROTECTED_PATTERNS regex (forward-slash-only) match.
+  // Fix: normalize all separators to forward slashes in output, regardless of platform.
+  it('normalizes backslashes to forward slashes on win32 (integration fix for protected patterns)', () => {
+    const result = pathNormalize('~/foo/bar.jsonl', {
+      homedir: 'C:\\Users\\Admin',
+      realpath: (p) => p,
+      resolve: path.win32.resolve,
+      platform: 'win32',
+      env: {},
+    });
+    expect(result).not.toMatch(/\\/);
+    expect(result.includes('/')).toBe(true);
+  });
   it('collapses .. via path.resolve', () => {
     // Use path.posix.resolve to simulate POSIX behaviour cross-platform
     const result = pathNormalize('a/../b', { realpath: (p) => p, resolve: path.posix.resolve, platform: 'linux', homedir: '/h', env: {} });