diff --git a/gitnexus-claude-plugin/hooks/registry-query.cjs b/gitnexus-claude-plugin/hooks/registry-query.cjs
index 0607602db..52abc3474 100644
--- a/gitnexus-claude-plugin/hooks/registry-query.cjs
+++ b/gitnexus-claude-plugin/hooks/registry-query.cjs
@@ -218,11 +218,11 @@ function branchSlug(rawRef) {
   return `${safe}-${hash}`;
 }
 
-// Mirror gitnexus/src/storage/storage-resolver.ts storageSlotName exactly
+// Mirror gitnexus/src/storage/storage-slot.ts slotNameForCanonicalPath exactly
 // (sanitize + sha256 of the canonical repo path, 12-hex suffix).
 function sanitizeSlotBasename(value) {
   // Cap first, then walk the tail once — same order as
-  // gitnexus/src/storage/storage-resolver.ts (avoids /[. ]+$/ ReDoS).
+  // gitnexus/src/storage/storage-slot.ts (avoids /[. ]+$/ ReDoS).
   const sanitized = value.replace(/[\u0000-\u001f<>:"/\\|?*]/g, '-').slice(0, 80);
   let end = sanitized.length;
   while (end > 0) {
@@ -231,9 +231,13 @@ function sanitizeSlotBasename(value) {
     end--;
   }
   const candidate = sanitized.slice(0, end) || 'repository';
-  return /^(con|prn|aux|nul|com[1-9]|lpt[1-9])$/i.test(candidate)
-    ? `repository-${candidate}`
-    : candidate;
+  // Windows also reserves device names with an extension (`CON.txt`); same
+  // platform branch as gitnexus/src/storage/storage-slot.ts.
+  const reserved =
+    process.platform === 'win32'
+      ? /^(con|prn|aux|nul|com[1-9]|lpt[1-9])(\..*)?$/i
+      : /^(con|prn|aux|nul|com[1-9]|lpt[1-9])$/i;
+  return reserved.test(candidate) ? `repository-${candidate}` : candidate;
 }
 
 function storageSlotName(repoPath) {
diff --git a/gitnexus-cursor-integration/hooks/registry-query.cjs b/gitnexus-cursor-integration/hooks/registry-query.cjs
index 0607602db..52abc3474 100644
--- a/gitnexus-cursor-integration/hooks/registry-query.cjs
+++ b/gitnexus-cursor-integration/hooks/registry-query.cjs
@@ -218,11 +218,11 @@ function branchSlug(rawRef) {
   return `${safe}-${hash}`;
 }
 
-// Mirror gitnexus/src/storage/storage-resolver.ts storageSlotName exactly
+// Mirror gitnexus/src/storage/storage-slot.ts slotNameForCanonicalPath exactly
 // (sanitize + sha256 of the canonical repo path, 12-hex suffix).
 function sanitizeSlotBasename(value) {
   // Cap first, then walk the tail once — same order as
-  // gitnexus/src/storage/storage-resolver.ts (avoids /[. ]+$/ ReDoS).
+  // gitnexus/src/storage/storage-slot.ts (avoids /[. ]+$/ ReDoS).
   const sanitized = value.replace(/[\u0000-\u001f<>:"/\\|?*]/g, '-').slice(0, 80);
   let end = sanitized.length;
   while (end > 0) {
@@ -231,9 +231,13 @@ function sanitizeSlotBasename(value) {
     end--;
   }
   const candidate = sanitized.slice(0, end) || 'repository';
-  return /^(con|prn|aux|nul|com[1-9]|lpt[1-9])$/i.test(candidate)
-    ? `repository-${candidate}`
-    : candidate;
+  // Windows also reserves device names with an extension (`CON.txt`); same
+  // platform branch as gitnexus/src/storage/storage-slot.ts.
+  const reserved =
+    process.platform === 'win32'
+      ? /^(con|prn|aux|nul|com[1-9]|lpt[1-9])(\..*)?$/i
+      : /^(con|prn|aux|nul|com[1-9]|lpt[1-9])$/i;
+  return reserved.test(candidate) ? `repository-${candidate}` : candidate;
 }
 
 function storageSlotName(repoPath) {
diff --git a/gitnexus-factory-plugin/hooks/registry-query.cjs b/gitnexus-factory-plugin/hooks/registry-query.cjs
index 0607602db..52abc3474 100644
--- a/gitnexus-factory-plugin/hooks/registry-query.cjs
+++ b/gitnexus-factory-plugin/hooks/registry-query.cjs
@@ -218,11 +218,11 @@ function branchSlug(rawRef) {
   return `${safe}-${hash}`;
 }
 
-// Mirror gitnexus/src/storage/storage-resolver.ts storageSlotName exactly
+// Mirror gitnexus/src/storage/storage-slot.ts slotNameForCanonicalPath exactly
 // (sanitize + sha256 of the canonical repo path, 12-hex suffix).
 function sanitizeSlotBasename(value) {
   // Cap first, then walk the tail once — same order as
-  // gitnexus/src/storage/storage-resolver.ts (avoids /[. ]+$/ ReDoS).
+  // gitnexus/src/storage/storage-slot.ts (avoids /[. ]+$/ ReDoS).
   const sanitized = value.replace(/[\u0000-\u001f<>:"/\\|?*]/g, '-').slice(0, 80);
   let end = sanitized.length;
   while (end > 0) {
@@ -231,9 +231,13 @@ function sanitizeSlotBasename(value) {
     end--;
   }
   const candidate = sanitized.slice(0, end) || 'repository';
-  return /^(con|prn|aux|nul|com[1-9]|lpt[1-9])$/i.test(candidate)
-    ? `repository-${candidate}`
-    : candidate;
+  // Windows also reserves device names with an extension (`CON.txt`); same
+  // platform branch as gitnexus/src/storage/storage-slot.ts.
+  const reserved =
+    process.platform === 'win32'
+      ? /^(con|prn|aux|nul|com[1-9]|lpt[1-9])(\..*)?$/i
+      : /^(con|prn|aux|nul|com[1-9]|lpt[1-9])$/i;
+  return reserved.test(candidate) ? `repository-${candidate}` : candidate;
 }
 
 function storageSlotName(repoPath) {
diff --git a/gitnexus/hooks/claude/registry-query.cjs b/gitnexus/hooks/claude/registry-query.cjs
index 0607602db..52abc3474 100644
--- a/gitnexus/hooks/claude/registry-query.cjs
+++ b/gitnexus/hooks/claude/registry-query.cjs
@@ -218,11 +218,11 @@ function branchSlug(rawRef) {
   return `${safe}-${hash}`;
 }
 
-// Mirror gitnexus/src/storage/storage-resolver.ts storageSlotName exactly
+// Mirror gitnexus/src/storage/storage-slot.ts slotNameForCanonicalPath exactly
 // (sanitize + sha256 of the canonical repo path, 12-hex suffix).
 function sanitizeSlotBasename(value) {
   // Cap first, then walk the tail once — same order as
-  // gitnexus/src/storage/storage-resolver.ts (avoids /[. ]+$/ ReDoS).
+  // gitnexus/src/storage/storage-slot.ts (avoids /[. ]+$/ ReDoS).
   const sanitized = value.replace(/[\u0000-\u001f<>:"/\\|?*]/g, '-').slice(0, 80);
   let end = sanitized.length;
   while (end > 0) {
@@ -231,9 +231,13 @@ function sanitizeSlotBasename(value) {
     end--;
   }
   const candidate = sanitized.slice(0, end) || 'repository';
-  return /^(con|prn|aux|nul|com[1-9]|lpt[1-9])$/i.test(candidate)
-    ? `repository-${candidate}`
-    : candidate;
+  // Windows also reserves device names with an extension (`CON.txt`); same
+  // platform branch as gitnexus/src/storage/storage-slot.ts.
+  const reserved =
+    process.platform === 'win32'
+      ? /^(con|prn|aux|nul|com[1-9]|lpt[1-9])(\..*)?$/i
+      : /^(con|prn|aux|nul|com[1-9]|lpt[1-9])$/i;
+  return reserved.test(candidate) ? `repository-${candidate}` : candidate;
 }
 
 function storageSlotName(repoPath) {
diff --git a/gitnexus/test/unit/hooks-shared-store.test.ts b/gitnexus/test/unit/hooks-shared-store.test.ts
index 186c72d9a..074767d3d 100644
--- a/gitnexus/test/unit/hooks-shared-store.test.ts
+++ b/gitnexus/test/unit/hooks-shared-store.test.ts
@@ -4,6 +4,7 @@ import os from 'os';
 import path from 'path';
 import { createRequire } from 'module';
 import { afterEach, beforeEach, describe, expect, it } from 'vitest';
+import { slotNameForCanonicalPath } from '../../src/storage/storage-slot.js';
 
 /**
  * #3352 — the Claude hook resolves a shared-store checkout to the commit
@@ -96,7 +97,7 @@ describe('registry-query shared store graph (#3352)', () => {
     fs.rmSync(tmp, { recursive: true, force: true });
   });
 
-  it('keeps the three hook copies byte-identical', () => {
+  it('keeps the four hook copies byte-identical', () => {
     const [primary, ...copies] = HOOK_COPIES.map((f) => fs.readFileSync(f, 'utf-8'));
     for (const copy of copies) expect(copy).toBe(primary);
   });
@@ -124,3 +125,70 @@ describe('registry-query shared store graph (#3352)', () => {
     );
   });
 });
+
+/**
+ * #3374 — the hook's slot name must match `slotNameForCanonicalPath` for
+ * device-name basenames on both platform branches, or a GITNEXUS_STORAGE_ROOT
+ * index is invisible to the hook. The checkout itself is never created (the
+ * hook falls back to the resolved path); only the slot is written. A real
+ * Windows host cannot create the POSIX-branch slot (`CON.txt-<hash>`), so the
+ * stubbed rows run on POSIX hosts, which exercise both branches.
+ */
+describe.skipIf(process.platform === 'win32')('registry-query slot name parity (#3374)', () => {
+  const realPlatform = process.platform;
+  const savedHome = process.env.GITNEXUS_HOME;
+  const savedStoragePath = process.env.GITNEXUS_STORAGE_PATH;
+  const savedStorageRoot = process.env.GITNEXUS_STORAGE_ROOT;
+  let tmp: string;
+
+  beforeEach(() => {
+    tmp = fs.realpathSync(fs.mkdtempSync(path.join(os.tmpdir(), 'gn-hook-slot-')));
+    process.env.GITNEXUS_HOME = path.join(tmp, 'home');
+    process.env.GITNEXUS_STORAGE_ROOT = path.join(tmp, 'root');
+    delete process.env.GITNEXUS_STORAGE_PATH;
+  });
+
+  afterEach(() => {
+    Object.defineProperty(process, 'platform', { value: realPlatform, configurable: true });
+    if (savedHome === undefined) delete process.env.GITNEXUS_HOME;
+    else process.env.GITNEXUS_HOME = savedHome;
+    if (savedStoragePath === undefined) delete process.env.GITNEXUS_STORAGE_PATH;
+    else process.env.GITNEXUS_STORAGE_PATH = savedStoragePath;
+    if (savedStorageRoot === undefined) delete process.env.GITNEXUS_STORAGE_ROOT;
+    else process.env.GITNEXUS_STORAGE_ROOT = savedStorageRoot;
+    fs.rmSync(tmp, { recursive: true, force: true });
+  });
+
+  const basenames = [
+    'CON',
+    'con.txt',
+    'NUL.tar.gz',
+    'COM1',
+    'LPT9.log',
+    'aux',
+    'prn.',
+    'normal',
+    'CONSOLE',
+    'com0.txt',
+  ];
+  const rows = (['win32', 'linux'] as const).flatMap((platform) =>
+    basenames.map((basename) => [platform, basename] as const),
+  );
+
+  it.each(rows)('on %s resolves the slot storage-slot.ts names for %s', (platform, basename) => {
+    Object.defineProperty(process, 'platform', { value: platform, configurable: true });
+    const checkout = path.join(tmp, 'repos', basename);
+    const slot = path.join(tmp, 'root', slotNameForCanonicalPath(checkout));
+    fs.mkdirSync(slot, { recursive: true });
+    fs.writeFileSync(
+      path.join(slot, 'gitnexus.json'),
+      JSON.stringify({ repoPath: checkout, storagePath: slot, lastCommit: 'abc' }),
+    );
+    fs.mkdirSync(path.join(tmp, 'home'), { recursive: true });
+    fs.writeFileSync(
+      path.join(tmp, 'home', 'registry.json'),
+      JSON.stringify([{ name: basename, path: checkout, indexedAt: '', lastCommit: '' }]),
+    );
+    expect(load(HOOK_COPIES[0]).findRegisteredRepo(checkout)?.storagePath).toBe(slot);
+  });
+});