diff --git a/tests/hooks/post-tool-use-auto-update.test.mjs b/tests/hooks/post-tool-use-auto-update.test.mjs
index 555eb7a8..e9ac94d0 100644
--- a/tests/hooks/post-tool-use-auto-update.test.mjs
+++ b/tests/hooks/post-tool-use-auto-update.test.mjs
@@ -1,5 +1,11 @@
 import { spawnSync } from 'node:child_process';
-import { mkdirSync, mkdtempSync, rmSync, writeFileSync } from 'node:fs';
+import {
+  mkdirSync,
+  mkdtempSync,
+  readFileSync,
+  rmSync,
+  writeFileSync,
+} from 'node:fs';
 import { tmpdir } from 'node:os';
 import { dirname, join, resolve } from 'node:path';
 import { fileURLToPath } from 'node:url';
@@ -13,34 +19,65 @@ const hookScript = join(
   'hooks',
   'post-tool-use-auto-update.mjs',
 );
+const hooksConfig = JSON.parse(
+  readFileSync(
+    join(repoRoot, 'understand-anything-plugin', 'hooks', 'hooks.json'),
+    'utf8',
+  ),
+);
 
 function runHook({
   command = 'git commit -m "test"',
   autoUpdate = true,
+  configContents,
+  createConfig = true,
   createGraph = true,
+  dataDirName = '.understand-anything',
+  input,
+  pluginRoot,
 } = {}) {
   const projectRoot = mkdtempSync(join(tmpdir(), 'ua-post-tool-use-'));
-  const dataDir = join(projectRoot, '.understand-anything');
+  const dataDir = join(projectRoot, dataDirName);
   mkdirSync(dataDir);
-  writeFileSync(join(dataDir, 'config.json'), JSON.stringify({ autoUpdate }));
+  if (createConfig) {
+    writeFileSync(
+      join(dataDir, 'config.json'),
+      configContents ?? JSON.stringify({ autoUpdate }),
+    );
+  }
   if (createGraph) writeFileSync(join(dataDir, 'knowledge-graph.json'), '{}');
 
-  const pluginRoot = join(projectRoot, 'plugin root');
+  const resolvedPluginRoot = pluginRoot ?? join(projectRoot, 'plugin root');
   const result = spawnSync(process.execPath, [hookScript], {
     cwd: projectRoot,
-    input: JSON.stringify({
-      tool_name: 'Bash',
-      tool_input: { command },
-    }),
-    env: { ...process.env, CLAUDE_PLUGIN_ROOT: pluginRoot },
+    input:
+      input ??
+      JSON.stringify({
+        tool_name: 'Bash',
+        tool_input: { command },
+      }),
+    env: { ...process.env, CLAUDE_PLUGIN_ROOT: resolvedPluginRoot },
     encoding: 'utf8',
   });
 
   rmSync(projectRoot, { recursive: true, force: true });
-  return { ...result, pluginRoot };
+  return { ...result, pluginRoot: resolvedPluginRoot };
 }
 
 describe('PostToolUse auto-update hook', () => {
+  it('is registered as the Bash PostToolUse handler', () => {
+    const registration = hooksConfig.hooks.PostToolUse[0];
+
+    expect(registration.matcher).toBe('Bash');
+    expect(registration.hooks).toEqual([
+      {
+        type: 'command',
+        command:
+          'node "${CLAUDE_PLUGIN_ROOT}/hooks/post-tool-use-auto-update.mjs"',
+      },
+    ]);
+  });
+
   it('injects the auto-update instruction as PostToolUse additional context', () => {
     const result = runHook();
     const output = JSON.parse(result.stdout);
@@ -60,6 +97,37 @@ describe('PostToolUse auto-update hook', () => {
     );
   });
 
+  it.each(['commit', 'merge', 'cherry-pick', 'rebase'])(
+    'recognizes git %s as a graph-changing operation',
+    (operation) => {
+      const result = runHook({ command: `git ${operation} example` });
+
+      expect(result.status).toBe(0);
+      expect(
+        JSON.parse(result.stdout).hookSpecificOutput.hookEventName,
+      ).toBe('PostToolUse');
+    },
+  );
+
+  it('preserves Windows-style plugin paths as valid JSON', () => {
+    const pluginRoot = 'C:\\Users\\Example Person\\understand-anything';
+    const result = runHook({ pluginRoot });
+    const output = JSON.parse(result.stdout);
+
+    expect(output.hookSpecificOutput.additionalContext).toContain(
+      `${pluginRoot}/hooks/auto-update-prompt.md`,
+    );
+  });
+
+  it('supports the legacy .ua data directory', () => {
+    const result = runHook({ dataDirName: '.ua' });
+
+    expect(result.status).toBe(0);
+    expect(JSON.parse(result.stdout).hookSpecificOutput.hookEventName).toBe(
+      'PostToolUse',
+    );
+  });
+
   it('stays silent for unrelated Bash commands', () => {
     const result = runHook({ command: 'git status --short' });
 
@@ -73,4 +141,17 @@ describe('PostToolUse auto-update hook', () => {
     expect(result.status).toBe(0);
     expect(result.stdout).toBe('');
   });
+
+  it.each([
+    ['malformed stdin', { input: '{not-json' }],
+    ['a missing config', { createConfig: false }],
+    ['a malformed config', { configContents: '{not-json' }],
+    ['a missing graph', { createGraph: false }],
+  ])('stays silent for %s', (_scenario, options) => {
+    const result = runHook(options);
+
+    expect(result.status).toBe(0);
+    expect(result.stderr).toBe('');
+    expect(result.stdout).toBe('');
+  });
 });