diff --git a/gitnexus-claude-plugin/hooks/gitnexus-hook.js b/gitnexus-claude-plugin/hooks/gitnexus-hook.js
index 7d8fbfda4..cd65750ba 100644
--- a/gitnexus-claude-plugin/hooks/gitnexus-hook.js
+++ b/gitnexus-claude-plugin/hooks/gitnexus-hook.js
@@ -102,6 +102,43 @@ function findGitNexusDir(startDir) {
   return null;
 }
 
+function isGitNexusServerCommand(command) {
+  const hasServerMode = /(?:^|\s)(mcp|serve)(?:\s|$)/.test(command);
+  const hasGitNexus = /(?:^|[/\\\s])gitnexus(?:\.cmd)?(?:\s|$)/.test(command) ||
+    /node_modules[/\\]gitnexus[/\\]/.test(command);
+  return hasServerMode && hasGitNexus;
+}
+
+function hasGitNexusServerOwner(gitNexusDir) {
+  const dbPath = path.join(gitNexusDir, 'lbug');
+  if (process.platform === 'win32' || !fs.existsSync(dbPath)) return false;
+
+  const lsof = spawnSync('lsof', ['-nP', '-t', '--', dbPath], {
+    encoding: 'utf-8',
+    timeout: 1000,
+    stdio: ['ignore', 'pipe', 'ignore'],
+  });
+  if (lsof.error) return lsof.error.code === 'ETIMEDOUT';
+
+  const pids = (lsof.stdout || '').split(/\s+/).filter(Boolean);
+  for (const pid of pids) {
+    if (Number(pid) === process.pid) continue;
+    const ps = spawnSync('ps', ['-p', pid, '-o', 'command='], {
+      encoding: 'utf-8',
+      timeout: 500,
+      stdio: ['ignore', 'pipe', 'ignore'],
+    });
+    if (!ps.error && isGitNexusServerCommand(ps.stdout || '')) return true;
+  }
+  return false;
+}
+
+function extractAugmentContext(stderr) {
+  const output = (stderr || '').trim();
+  const marker = output.indexOf('[GitNexus]');
+  return marker === -1 ? '' : output.slice(marker).trim();
+}
+
 /**
  * Extract search pattern from tool input.
  */
@@ -217,7 +254,8 @@ function sendHookResponse(hookEventName, message) {
 function handlePreToolUse(input) {
   const cwd = input.cwd || process.cwd();
   if (!path.isAbsolute(cwd)) return;
-  if (!findGitNexusDir(cwd)) return;
+  const gitNexusDir = findGitNexusDir(cwd);
+  if (!gitNexusDir) return;
 
   const toolName = input.tool_name || '';
   const toolInput = input.tool_input || {};
@@ -226,19 +264,20 @@ function handlePreToolUse(input) {
 
   const pattern = extractPattern(toolName, toolInput);
   if (!pattern || pattern.length < 3) return;
+  if (hasGitNexusServerOwner(gitNexusDir)) return;
 
   let result = '';
   try {
     const child = runGitNexusCli(['augment', '--', pattern], cwd, 7000);
     if (!child.error && child.status === 0) {
-      result = child.stderr || '';
+      result = extractAugmentContext(child.stderr || '');
     }
   } catch {
     /* graceful failure */
   }
 
-  if (result && result.trim()) {
-    sendHookResponse('PreToolUse', result.trim());
+  if (result) {
+    sendHookResponse('PreToolUse', result);
   }
 }
 
diff --git a/gitnexus/hooks/claude/gitnexus-hook.cjs b/gitnexus/hooks/claude/gitnexus-hook.cjs
index 7bfa150cd..6ec8bd3ee 100755
--- a/gitnexus/hooks/claude/gitnexus-hook.cjs
+++ b/gitnexus/hooks/claude/gitnexus-hook.cjs
@@ -102,6 +102,43 @@ function findGitNexusDir(startDir) {
   return null;
 }
 
+function isGitNexusServerCommand(command) {
+  const hasServerMode = /(?:^|\s)(mcp|serve)(?:\s|$)/.test(command);
+  const hasGitNexus = /(?:^|[/\\\s])gitnexus(?:\.cmd)?(?:\s|$)/.test(command) ||
+    /node_modules[/\\]gitnexus[/\\]/.test(command);
+  return hasServerMode && hasGitNexus;
+}
+
+function hasGitNexusServerOwner(gitNexusDir) {
+  const dbPath = path.join(gitNexusDir, 'lbug');
+  if (process.platform === 'win32' || !fs.existsSync(dbPath)) return false;
+
+  const lsof = spawnSync('lsof', ['-nP', '-t', '--', dbPath], {
+    encoding: 'utf-8',
+    timeout: 1000,
+    stdio: ['ignore', 'pipe', 'ignore'],
+  });
+  if (lsof.error) return lsof.error.code === 'ETIMEDOUT';
+
+  const pids = (lsof.stdout || '').split(/\s+/).filter(Boolean);
+  for (const pid of pids) {
+    if (Number(pid) === process.pid) continue;
+    const ps = spawnSync('ps', ['-p', pid, '-o', 'command='], {
+      encoding: 'utf-8',
+      timeout: 500,
+      stdio: ['ignore', 'pipe', 'ignore'],
+    });
+    if (!ps.error && isGitNexusServerCommand(ps.stdout || '')) return true;
+  }
+  return false;
+}
+
+function extractAugmentContext(stderr) {
+  const output = (stderr || '').trim();
+  const marker = output.indexOf('[GitNexus]');
+  return marker === -1 ? '' : output.slice(marker).trim();
+}
+
 /**
  * Extract search pattern from tool input.
  */
@@ -167,6 +204,9 @@ function extractPattern(toolName, toolInput) {
  * 3. Fall back to npx (returns empty string)
  */
 function resolveCliPath() {
+  if (process.env.GITNEXUS_HOOK_CLI_PATH !== undefined) {
+    return process.env.GITNEXUS_HOOK_CLI_PATH;
+  }
   let cliPath = path.resolve(__dirname, '..', '..', 'dist', 'cli', 'index.js');
   if (!fs.existsSync(cliPath)) {
     try {
@@ -207,7 +247,8 @@ function runGitNexusCli(cliPath, args, cwd, timeout) {
 function handlePreToolUse(input) {
   const cwd = input.cwd || process.cwd();
   if (!path.isAbsolute(cwd)) return;
-  if (!findGitNexusDir(cwd)) return;
+  const gitNexusDir = findGitNexusDir(cwd);
+  if (!gitNexusDir) return;
 
   const toolName = input.tool_name || '';
   const toolInput = input.tool_input || {};
@@ -216,20 +257,21 @@ function handlePreToolUse(input) {
 
   const pattern = extractPattern(toolName, toolInput);
   if (!pattern || pattern.length < 3) return;
+  if (hasGitNexusServerOwner(gitNexusDir)) return;
 
   const cliPath = resolveCliPath();
   let result = '';
   try {
     const child = runGitNexusCli(cliPath, ['augment', '--', pattern], cwd, 7000);
     if (!child.error && child.status === 0) {
-      result = child.stderr || '';
+      result = extractAugmentContext(child.stderr || '');
     }
   } catch {
     /* graceful failure */
   }
 
-  if (result && result.trim()) {
-    sendHookResponse('PreToolUse', result.trim());
+  if (result) {
+    sendHookResponse('PreToolUse', result);
   }
 }
 
diff --git a/gitnexus/package-lock.json b/gitnexus/package-lock.json
index dfc5e3c4c..7aa9dc7bf 100644
--- a/gitnexus/package-lock.json
+++ b/gitnexus/package-lock.json
@@ -63,7 +63,7 @@
         "vitest": "^4.0.18"
       },
       "engines": {
-        "node": ">=20.0.0"
+        "node": ">=22.0.0"
       },
       "optionalDependencies": {
         "node-addon-api": "^8.0.0",
diff --git a/gitnexus/test/unit/hooks.test.ts b/gitnexus/test/unit/hooks.test.ts
index da19da002..c7c236c49 100644
--- a/gitnexus/test/unit/hooks.test.ts
+++ b/gitnexus/test/unit/hooks.test.ts
@@ -18,6 +18,7 @@
  */
 import { describe, it, expect, beforeAll, afterAll } from 'vitest';
 import { spawnSync } from 'child_process';
+import type { WriteFileOptions } from 'fs';
 import fs from 'fs';
 import path from 'path';
 import os from 'os';
@@ -99,6 +100,45 @@ function createGlobalRegistry(homeDir: string, marker: 'both' | 'registry' | 're
   }
 }
 
+function writeExecutable(filePath: string, content: string) {
+  fs.writeFileSync(filePath, content, { mode: 0o755 } as WriteFileOptions);
+}
+
+function createHookToolDir(options: {
+  gitnexusStderr?: string;
+  gitnexusMarkerPath?: string;
+  lsofOutput?: string;
+  psOutput?: string;
+}) {
+  const binDir = fs.mkdtempSync(path.join(os.tmpdir(), 'gitnexus-hook-bin-'));
+  const gitnexusStderr = JSON.stringify(options.gitnexusStderr ?? '');
+  const markerPath = JSON.stringify(options.gitnexusMarkerPath ?? '');
+
+  const fakeGitNexus = `#!/usr/bin/env node\nconst fs = require('fs');\nconst marker = ${markerPath};\nif (marker) fs.writeFileSync(marker, 'called');\nprocess.stderr.write(${gitnexusStderr});\n`;
+  writeExecutable(path.join(binDir, 'gitnexus'), fakeGitNexus);
+  writeExecutable(path.join(binDir, 'gitnexus-cli.js'), fakeGitNexus);
+
+  writeExecutable(
+    path.join(binDir, 'lsof'),
+    `#!/usr/bin/env node\nprocess.stdout.write(${JSON.stringify(options.lsofOutput ?? '')});\nprocess.exit(0);\n`,
+  );
+
+  writeExecutable(
+    path.join(binDir, 'ps'),
+    `#!/usr/bin/env node\nprocess.stdout.write(${JSON.stringify(options.psOutput ?? '')});\nprocess.exit(0);\n`,
+  );
+
+  return binDir;
+}
+
+function hookEnv(binDir: string) {
+  return {
+    ...process.env,
+    PATH: `${binDir}${path.delimiter}${process.env.PATH || ''}`,
+    GITNEXUS_HOOK_CLI_PATH: path.join(binDir, 'gitnexus-cli.js'),
+  };
+}
+
 // ─── Both hook files should exist ───────────────────────────────────
 
 describe('Hook files exist', () => {
@@ -294,6 +334,96 @@ describe('Git mutation regex', () => {
   }
 });
 
+// ─── Integration: PreToolUse augmentation filtering ─────────────────
+
+describe('PreToolUse augmentation filtering (integration)', () => {
+  for (const [label, hookPath] of [
+    ['CJS', CJS_HOOK],
+    ['Plugin', PLUGIN_HOOK],
+  ] as const) {
+    it(`${label}: emits valid GitNexus augmentation context`, () => {
+      const binDir = createHookToolDir({
+        gitnexusStderr: '[GitNexus] 1 related symbol found:\n\nvalidateUser (src/auth.ts)\n',
+      });
+      try {
+        const result = runHook(
+          hookPath,
+          {
+            hook_event_name: 'PreToolUse',
+            tool_name: 'Grep',
+            tool_input: { pattern: 'validateUser' },
+            cwd: tmpDir,
+          },
+          undefined,
+          { env: hookEnv(binDir) },
+        );
+
+        const output = parseHookOutput(result.stdout);
+        expect(output).not.toBeNull();
+        expect(output!.hookEventName).toBe('PreToolUse');
+        expect(output!.additionalContext).toContain('[GitNexus] 1 related symbol found');
+      } finally {
+        fs.rmSync(binDir, { recursive: true, force: true });
+      }
+    });
+
+    it(`${label}: suppresses LadybugDB lock warnings from augment stderr`, () => {
+      const binDir = createHookToolDir({
+        gitnexusStderr:
+          'GitNexus: FTS extension load failed: IO exception: Could not set lock on file : /tmp/repo/.gitnexus/lbug\n',
+      });
+      try {
+        const result = runHook(
+          hookPath,
+          {
+            hook_event_name: 'PreToolUse',
+            tool_name: 'Grep',
+            tool_input: { pattern: 'validateUser' },
+            cwd: tmpDir,
+          },
+          undefined,
+          { env: hookEnv(binDir) },
+        );
+
+        expect(result.stdout.trim()).toBe('');
+      } finally {
+        fs.rmSync(binDir, { recursive: true, force: true });
+      }
+    });
+
+    it(`${label}: skips augment when a GitNexus MCP process owns the repo DB`, () => {
+      const markerPath = path.join(os.tmpdir(), `gitnexus-hook-called-${process.pid}-${label}`);
+      const lbugPath = path.join(gitNexusDir, 'lbug');
+      fs.writeFileSync(lbugPath, '');
+      fs.rmSync(markerPath, { force: true });
+      const binDir = createHookToolDir({
+        gitnexusMarkerPath: markerPath,
+        lsofOutput: '12345\n',
+        psOutput: 'node /tmp/node_modules/.bin/gitnexus mcp\n',
+      });
+      try {
+        const result = runHook(
+          hookPath,
+          {
+            hook_event_name: 'PreToolUse',
+            tool_name: 'Grep',
+            tool_input: { pattern: 'validateUser' },
+            cwd: tmpDir,
+          },
+          undefined,
+          { env: hookEnv(binDir) },
+        );
+
+        expect(result.stdout.trim()).toBe('');
+        expect(fs.existsSync(markerPath)).toBe(false);
+      } finally {
+        fs.rmSync(markerPath, { force: true });
+        fs.rmSync(binDir, { recursive: true, force: true });
+      }
+    });
+  }
+});
+
 // ─── Integration: PostToolUse staleness detection ───────────────────
 
 describe('PostToolUse staleness detection (integration)', () => {
diff --git a/gitnexus/test/utils/hook-test-helpers.ts b/gitnexus/test/utils/hook-test-helpers.ts
index 6f5c5fbfd..3f519bc81 100644
--- a/gitnexus/test/utils/hook-test-helpers.ts
+++ b/gitnexus/test/utils/hook-test-helpers.ts
@@ -7,12 +7,14 @@ export function runHook(
   hookPath: string,
   input: Record<string, any>,
   cwd?: string,
+  options: { env?: NodeJS.ProcessEnv } = {},
 ): { stdout: string; stderr: string; status: number | null } {
   const result = spawnSync(process.execPath, [hookPath], {
     input: JSON.stringify(input),
     encoding: 'utf-8',
     timeout: 10000,
     cwd,
+    env: options.env,
     stdio: ['pipe', 'pipe', 'pipe'],
   });
   return {