Fix Windows hook migration dedupe

Normalize hook command separators before matching Impeccable-owned entries so updates replace legacy Windows guards instead of duplicating them.\n\nAI assistance: Codex implemented and validated this change under maintainer authorization.

cli/bin/commands/skills.mjs

@@ -1534,7 +1534,8 @@ function hookInstalledForProvider(root, provider) {
 
 function valueHasImpeccableHookMarker(value) {
   if (typeof value === 'string') {
-    return IMPECCABLE_HOOK_COMMAND_MARKERS.some(marker => value.includes(marker));
+    const normalized = value.replace(/\\/g, '/');
+    return IMPECCABLE_HOOK_COMMAND_MARKERS.some(marker => normalized.includes(marker));
   }
   if (Array.isArray(value)) return value.some(valueHasImpeccableHookMarker);
   if (value && typeof value === 'object') {

tests/skills-cli.test.js

@@ -1649,6 +1649,35 @@ describe('hook manifest merge helpers', () => {
       'node .cursor/skills/impeccable/scripts/hook-before-edit.mjs',
     ]);
   });
+
+  test('mergeHookManifests replaces legacy Windows-path Claude hooks (#604)', () => {
+    const legacyPath = 'C:\\Users\\alice\\.claude\\skills\\impeccable\\scripts\\hook.mjs';
+    const legacyCommand = `[ ! -f "${legacyPath}" ] || node "${legacyPath}"`;
+    const freshCommand = `node -e "guard" "${legacyPath}"`;
+    const merged = mergeHookManifests(
+      {
+        hooks: {
+          PostToolUse: [{ matcher: 'Edit|Write|MultiEdit', hooks: [
+            { type: 'command', command: legacyCommand },
+          ] }],
+          Stop: [{ hooks: [{ type: 'command', command: legacyCommand }] }],
+        },
+      },
+      {
+        hooks: {
+          PostToolUse: [{ matcher: 'Edit|Write|MultiEdit', hooks: [
+            { type: 'command', command: freshCommand },
+          ] }],
+          Stop: [{ hooks: [{ type: 'command', command: freshCommand }] }],
+        },
+      },
+    );
+
+    expect(merged.hooks.PostToolUse).toHaveLength(1);
+    expect(merged.hooks.Stop).toHaveLength(1);
+    expect(merged.hooks.PostToolUse[0].hooks[0].command).toBe(freshCommand);
+    expect(merged.hooks.Stop[0].hooks[0].command).toBe(freshCommand);
+  });
 });
 
 // ─── Hook command path resolution (issue #399, part 1) ───────────────────────