diff --git a/README.md b/README.md
index 6beadb63d..3c3a28c27 100644
--- a/README.md
+++ b/README.md
@@ -120,7 +120,7 @@ To configure MCP for your editor, run `npx gitnexus setup` once — or set it up
 | Editor                | MCP | Skills | Hooks (auto-augment) | Support        |
 | --------------------- | --- | ------ | -------------------- | -------------- |
 | **Claude Code** | Yes | Yes    | Yes (PreToolUse + PostToolUse) | **Full** |
-| **Cursor**      | Yes | Yes    | —                   | MCP + Skills   |
+| **Cursor**      | Yes | Yes    | Yes (postToolUse, [manual install](gitnexus-cursor-integration/README.md#hook-install)) | **Full** |
 | **Codex**       | Yes | Yes    | —                   | MCP + Skills   |
 | **Windsurf**    | Yes | —     | —                   | MCP            |
 | **OpenCode**    | Yes | Yes    | —                   | MCP + Skills   |
diff --git a/gitnexus-cursor-integration/README.md b/gitnexus-cursor-integration/README.md
new file mode 100644
index 000000000..0da8b1981
--- /dev/null
+++ b/gitnexus-cursor-integration/README.md
@@ -0,0 +1,89 @@
+# GitNexus — Cursor integration
+
+Static config that adds GitNexus knowledge-graph augmentation and skill files to Cursor.
+
+> **Hooks require Cursor 2.4+.** Earlier versions don't expose `postToolUse` and the hook will silently no-op.
+
+## What you get
+
+| Layer                     | What it does                                                                                                                              | How it's installed                                                              |
+| ------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------- |
+| **MCP**                   | `gitnexus` MCP server with 16 tools (`query`, `context`, `impact`, `detect_changes`, `rename`, …)                                         | `npx gitnexus setup` writes `~/.cursor/mcp.json` automatically.                 |
+| **Skills**                | `/gitnexus-exploring`, `/gitnexus-debugging`, `/gitnexus-impact-analysis`, `/gitnexus-refactoring`, `/gitnexus-pr-review` markdown skills | `npx gitnexus setup` copies them to `~/.cursor/skills/gitnexus/`.               |
+| **Hooks** _(this README)_ | `postToolUse` hook that enriches `Shell` / `Read` / `Grep` tool calls with graph context — same augmentation Claude Code gets             | **Manual** — copy the two files described below into your project's `.cursor/`. |
+
+## Hook install
+
+Cursor 2.4+ reads `.cursor/hooks.json` from the project root and runs hook commands with the project root as the working directory ([docs](https://cursor.com/docs/agent/hooks)).
+
+From this repo's `gitnexus-cursor-integration/hooks/`, copy the two files into your **project root**:
+
+```text
+<your-project>/
+├── .cursor/
+│   └── hooks.json              ← from gitnexus-cursor-integration/hooks/hooks.json
+└── hooks/
+    └── gitnexus-hook.cjs       ← from gitnexus-cursor-integration/hooks/gitnexus-hook.cjs
+```
+
+Equivalent shell commands (run from your project root, with `$GITNEXUS_REPO` pointing at a clone of this repo):
+
+```bash
+mkdir -p .cursor hooks
+cp "$GITNEXUS_REPO/gitnexus-cursor-integration/hooks/hooks.json"        .cursor/hooks.json
+cp "$GITNEXUS_REPO/gitnexus-cursor-integration/hooks/gitnexus-hook.cjs" hooks/gitnexus-hook.cjs
+```
+
+If you already have a `.cursor/hooks.json`, merge the `hooks.postToolUse` array rather than overwriting.
+
+### Verify
+
+1. Index the project: `npx gitnexus analyze`
+2. Reload the Cursor window so it picks up the new hook config.
+3. Ask the agent something that triggers `Read` / `Grep` / `Shell rg`. You should see a `[GitNexus]` block appended to the tool result.
+4. Diagnose silent no-ops by setting `GITNEXUS_DEBUG=1` in your shell environment — the hook will write Cursor's raw event payload to stderr so you can verify field names.
+
+### What's installed manually vs. automated
+
+| Step                                                                 | Automated by `gitnexus setup`? |
+| -------------------------------------------------------------------- | ------------------------------ |
+| `~/.cursor/mcp.json`                                                 | ✅                             |
+| `~/.cursor/skills/gitnexus/*`                                        | ✅                             |
+| `<project>/.cursor/hooks.json` + `<project>/hooks/gitnexus-hook.cjs` | ❌ — copy manually (see above) |
+
+Hook install is per-project (Cursor scopes hooks to a project root); skills and MCP config are global.
+
+## Hook contract
+
+The hook receives a JSON event on stdin matching Cursor 2.4's `postToolUse` shape:
+
+```json
+{
+  "tool_name": "Grep" | "Read" | "Shell",
+  "tool_input": { /* tool-specific */ },
+  "tool_output": { /* optional */ },
+  "cwd": "/absolute/path/to/project"
+}
+```
+
+It writes augmentation context to stdout as:
+
+```json
+{ "additional_context": "[GitNexus] …" }
+```
+
+Empty stdout means "no augmentation, continue normally" — the hook never blocks the tool.
+
+### Pattern extraction per tool
+
+| Tool    | Pattern source                                                                                                         | Notes                                                                                                |
+| ------- | ---------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------- |
+| `Grep`  | `tool_input.query` (also `pattern`, `regex`, `q`, `search`, `searchQuery`)                                             | Last-resort fallback: longest string value in `tool_input` (≥ 3 chars).                              |
+| `Read`  | basename of `tool_input.target_file` (also `file_path`, `filePath`, `path`, `file`), stripped to identifier characters | `auth/handler.ts` → `handler`.                                                                       |
+| `Shell` | First positional argument after `rg` / `grep` in `tool_input.command`                                                  | Best-effort tokenizer; quoted multi-word patterns (`rg "User Service"`) extract the first word only. |
+
+## Troubleshooting
+
+- **Nothing happens** — Confirm Cursor is on 2.4+ and the project root has both `.cursor/hooks.json` and the script at `hooks/gitnexus-hook.cjs`. Then `npx gitnexus list` to confirm the project is indexed.
+- **`gitnexus` not found** — The hook prefers a locally-resolvable `gitnexus/dist/cli/index.js` and falls back to `npx -y gitnexus`. Install globally with `npm i -g gitnexus` to skip the npx cold-start latency.
+- **Wrong pattern extracted** — Set `GITNEXUS_DEBUG=1` and run a tool call. The raw stdin payload is logged to stderr; use it to confirm Cursor's actual `tool_input` field names against the table above. If they differ, file an issue with the captured payload.
diff --git a/gitnexus-cursor-integration/hooks/augment-shell.sh b/gitnexus-cursor-integration/hooks/augment-shell.sh
deleted file mode 100644
index 48ea185b0..000000000
--- a/gitnexus-cursor-integration/hooks/augment-shell.sh
+++ /dev/null
@@ -1,50 +0,0 @@
-#!/bin/bash
-# GitNexus beforeShellExecution hook for Cursor
-# Receives JSON on stdin with { command, cwd, timeout }
-# Returns JSON on stdout with { permission, agent_message }
-#
-# Extracts search pattern from grep/rg commands, runs gitnexus augment,
-# and injects the enriched context via agent_message.
-
-INPUT=$(cat)
-
-COMMAND=$(echo "$INPUT" | jq -r '.command // empty' 2>/dev/null)
-
-if [ -z "$COMMAND" ]; then
-  echo '{"permission":"allow"}'
-  exit 0
-fi
-
-# Skip non-search commands
-case "$COMMAND" in
-  cd\ *|npm\ *|yarn\ *|pnpm\ *|git\ commit*|git\ push*|git\ pull*|mkdir\ *|rm\ *|cp\ *|mv\ *|echo\ *|cat\ *)
-    echo '{"permission":"allow"}'
-    exit 0
-    ;;
-esac
-
-# Extract search pattern from rg/grep commands
-PATTERN=""
-if echo "$COMMAND" | grep -qE '\brg\b'; then
-  PATTERN=$(echo "$COMMAND" | sed -n "s/.*\brg\s\+\(--[^ ]*\s\+\)*['\"]\\?\([^'\";\| >]*\\).*/\2/p")
-elif echo "$COMMAND" | grep -qE '\bgrep\b'; then
-  PATTERN=$(echo "$COMMAND" | sed -n "s/.*\bgrep\s\+\(-[^ ]*\s\+\)*['\"]\\?\([^'\";\| >]*\\).*/\2/p")
-fi
-
-if [ -z "$PATTERN" ] || [ ${#PATTERN} -lt 3 ]; then
-  echo '{"permission":"allow"}'
-  exit 0
-fi
-
-# Run gitnexus augment
-RESULT=$(npx -y gitnexus augment "$PATTERN" 2>/dev/null)
-
-if [ -n "$RESULT" ]; then
-  # Escape for JSON
-  ESCAPED=$(echo "$RESULT" | jq -Rs .)
-  echo "{\"permission\":\"allow\",\"agent_message\":$ESCAPED}"
-else
-  echo '{"permission":"allow"}'
-fi
-
-exit 0
diff --git a/gitnexus-cursor-integration/hooks/gitnexus-hook.cjs b/gitnexus-cursor-integration/hooks/gitnexus-hook.cjs
new file mode 100644
index 000000000..0ea336619
--- /dev/null
+++ b/gitnexus-cursor-integration/hooks/gitnexus-hook.cjs
@@ -0,0 +1,259 @@
+#!/usr/bin/env node
+/**
+ * GitNexus Cursor postToolUse Hook
+ *
+ * Receives a JSON event on stdin describing a finished tool call, derives a
+ * search pattern (Grep query, Read file basename, or rg/grep arg from a Shell
+ * command), runs `gitnexus augment <pattern>`, and emits the enriched context
+ * back as `{ additional_context: "..." }` so the agent sees it alongside the
+ * tool result.
+ *
+ * Replaces the legacy beforeShellExecution / augment-shell.sh pipeline:
+ *   - Cross-platform (no bash, no jq — runs on Windows out of the box)
+ *   - Covers Read and Grep, not just Shell rg/grep
+ *
+ * Cursor 2.4+ generic hooks: https://cursor.com/docs/agent/hooks
+ */
+
+const fs = require('fs');
+const path = require('path');
+const { spawnSync } = require('child_process');
+
+function readInput() {
+  try {
+    const data = fs.readFileSync(0, 'utf-8');
+    return JSON.parse(data);
+  } catch {
+    return {};
+  }
+}
+
+function isGlobalRegistryDir(candidate) {
+  if (fs.existsSync(path.join(candidate, 'meta.json'))) return false;
+  return (
+    fs.existsSync(path.join(candidate, 'registry.json')) ||
+    fs.existsSync(path.join(candidate, 'repos'))
+  );
+}
+
+function walkForGitNexusDir(startDir) {
+  let dir = startDir;
+  for (let i = 0; i < 5; i++) {
+    const candidate = path.join(dir, '.gitnexus');
+    if (fs.existsSync(candidate)) {
+      if (!isGlobalRegistryDir(candidate)) return candidate;
+    }
+    const parent = path.dirname(dir);
+    if (parent === dir) break;
+    dir = parent;
+  }
+  return null;
+}
+
+function findCanonicalRepoRoot(cwd) {
+  try {
+    const result = spawnSync('git', ['rev-parse', '--path-format=absolute', '--git-common-dir'], {
+      encoding: 'utf-8',
+      timeout: 2000,
+      cwd,
+      stdio: ['pipe', 'pipe', 'pipe'],
+    });
+    if (result.error || result.status !== 0) return null;
+    const commonDir = (result.stdout || '').trim();
+    if (!commonDir || !path.isAbsolute(commonDir)) return null;
+    return path.dirname(commonDir);
+  } catch {
+    return null;
+  }
+}
+
+function findGitNexusDir(startDir) {
+  const cwd = startDir || process.cwd();
+  const fromCwd = walkForGitNexusDir(cwd);
+  if (fromCwd) return fromCwd;
+  const canonicalRoot = findCanonicalRepoRoot(cwd);
+  if (canonicalRoot && canonicalRoot !== cwd) {
+    return walkForGitNexusDir(canonicalRoot);
+  }
+  return null;
+}
+
+function parseRgGrepPattern(cmd) {
+  const tokens = cmd.split(/\s+/);
+  let foundCmd = false;
+  let skipNext = false;
+  const flagsWithValues = new Set([
+    '-e',
+    '-f',
+    '-m',
+    '-A',
+    '-B',
+    '-C',
+    '-g',
+    '--glob',
+    '-t',
+    '--type',
+    '--include',
+    '--exclude',
+  ]);
+
+  for (const token of tokens) {
+    if (skipNext) {
+      skipNext = false;
+      continue;
+    }
+    if (!foundCmd) {
+      if (/\brg$|\bgrep$/.test(token)) foundCmd = true;
+      continue;
+    }
+    if (token.startsWith('-')) {
+      if (flagsWithValues.has(token)) skipNext = true;
+      continue;
+    }
+    const cleaned = token.replace(/['"]/g, '');
+    return cleaned.length >= 3 ? cleaned : null;
+  }
+  return null;
+}
+
+/**
+ * Extract a search pattern from the tool input. Cursor 2.4 docs at
+ * https://cursor.com/docs/agent/hooks list the tool *matchers* but do not
+ * formally specify the per-tool tool_input field names, so we probe a
+ * generous set of MCP-style aliases. As a last-resort fallback for Grep
+ * (the highest-frequency search path) we also accept the longest plausible
+ * string value in tool_input. Set GITNEXUS_DEBUG=1 to log the raw payload
+ * to stderr if Cursor changes the contract and aliases stop matching.
+ */
+function pickLongestStringValue(obj) {
+  let best = null;
+  if (!obj || typeof obj !== 'object') return null;
+  for (const v of Object.values(obj)) {
+    if (typeof v === 'string' && v.length >= 3 && (!best || v.length > best.length)) {
+      best = v;
+    }
+  }
+  return best;
+}
+
+function extractPattern(toolName, toolInput) {
+  const t = (toolName || '').toLowerCase();
+
+  if (t === 'grep') {
+    const aliases = [
+      toolInput.query,
+      toolInput.pattern,
+      toolInput.regex,
+      toolInput.q,
+      toolInput.search,
+      toolInput.searchQuery,
+    ];
+    for (const a of aliases) {
+      if (typeof a === 'string' && a.length >= 3) return a;
+    }
+    // Last resort: scan tool_input for any reasonable-looking string value.
+    return pickLongestStringValue(toolInput);
+  }
+
+  if (t === 'read') {
+    const filePath =
+      toolInput.target_file ||
+      toolInput.file_path ||
+      toolInput.filePath ||
+      toolInput.path ||
+      toolInput.file ||
+      '';
+    if (!filePath) return null;
+    const base = path.basename(String(filePath), path.extname(String(filePath)));
+    const cleaned = base.replace(/[^a-zA-Z0-9_]/g, '');
+    return cleaned.length >= 3 ? cleaned : null;
+  }
+
+  if (t === 'shell') {
+    const cmd = toolInput.command || '';
+    if (!/\brg\b|\bgrep\b/.test(cmd)) return null;
+    // NOTE: parseRgGrepPattern uses split(/\s+/) and cannot handle shell
+    // quoting. `rg "User Service" src/` returns "User" (the first token
+    // after the rg/grep arg, with surrounding quotes stripped) — the
+    // multi-word pattern is intentionally not reconstructed since BM25 is
+    // already token-tolerant. Quoted single tokens (`rg "validateUser"`)
+    // work fine.
+    return parseRgGrepPattern(cmd);
+  }
+
+  return null;
+}
+
+function resolveCliPath() {
+  try {
+    return require.resolve('gitnexus/dist/cli/index.js');
+  } catch {
+    return '';
+  }
+}
+
+function runGitNexusCli(cliPath, args, cwd, timeout) {
+  const isWin = process.platform === 'win32';
+  if (cliPath) {
+    return spawnSync(process.execPath, [cliPath, ...args], {
+      encoding: 'utf-8',
+      timeout,
+      cwd,
+      stdio: ['pipe', 'pipe', 'pipe'],
+    });
+  }
+  return spawnSync(isWin ? 'npx.cmd' : 'npx', ['-y', 'gitnexus', ...args], {
+    encoding: 'utf-8',
+    timeout: timeout + 5000,
+    cwd,
+    stdio: ['pipe', 'pipe', 'pipe'],
+  });
+}
+
+function main() {
+  try {
+    const input = readInput();
+    if (process.env.GITNEXUS_DEBUG) {
+      // Echo the payload so users can capture Cursor's actual contract when
+      // diagnosing why augmentation isn't firing. Stderr only — stdout is
+      // reserved for the JSON response Cursor consumes.
+      try {
+        process.stderr.write(
+          `GitNexus Cursor hook stdin: ${JSON.stringify(input).slice(0, 500)}\n`,
+        );
+      } catch {
+        /* never let debug logging break the hook */
+      }
+    }
+    const cwd = input.cwd || process.cwd();
+    if (!path.isAbsolute(cwd)) return;
+    if (!findGitNexusDir(cwd)) return;
+
+    const toolName = input.tool_name || '';
+    const toolInput = input.tool_input || {};
+
+    const pattern = extractPattern(toolName, toolInput);
+    if (!pattern || pattern.length < 3) return;
+
+    const cliPath = resolveCliPath();
+    let result = '';
+    try {
+      const child = runGitNexusCli(cliPath, ['augment', '--', pattern], cwd, 7000);
+      if (!child.error && child.status === 0) {
+        result = child.stderr || '';
+      }
+    } catch {
+      /* graceful failure */
+    }
+
+    if (result && result.trim()) {
+      console.log(JSON.stringify({ additional_context: result.trim() }));
+    }
+  } catch (err) {
+    if (process.env.GITNEXUS_DEBUG) {
+      console.error('GitNexus Cursor hook error:', (err.message || '').slice(0, 200));
+    }
+  }
+}
+
+main();
diff --git a/gitnexus-cursor-integration/hooks/hooks.json b/gitnexus-cursor-integration/hooks/hooks.json
index ede0dfbf3..9ae542c14 100644
--- a/gitnexus-cursor-integration/hooks/hooks.json
+++ b/gitnexus-cursor-integration/hooks/hooks.json
@@ -1,11 +1,11 @@
 {
   "version": 1,
   "hooks": {
-    "beforeShellExecution": [
+    "postToolUse": [
       {
-        "command": "./hooks/augment-shell.sh",
-        "timeout": 5,
-        "matcher": "\\brg\\b|\\bgrep\\b"
+        "matcher": "Shell|Read|Grep",
+        "command": "node ./hooks/gitnexus-hook.cjs",
+        "timeout": 10
       }
     ]
   }
diff --git a/gitnexus/README.md b/gitnexus/README.md
index 8a5144598..55cdc12f7 100644
--- a/gitnexus/README.md
+++ b/gitnexus/README.md
@@ -33,7 +33,7 @@ To configure MCP for your editor, run `npx gitnexus setup` once — or set it up
 | Editor | MCP | Skills | Hooks (auto-augment) | Support |
 |--------|-----|--------|---------------------|---------|
 | **Claude Code** | Yes | Yes | Yes (PreToolUse) | **Full** |
-| **Cursor** | Yes | Yes | — | MCP + Skills |
+| **Cursor** | Yes | Yes | Yes (postToolUse, [manual install](../gitnexus-cursor-integration/README.md#hook-install)) | **Full** |
 | **Codex** | Yes | Yes | — | MCP + Skills |
 | **Windsurf** | Yes | — | — | MCP |
 | **OpenCode** | Yes | Yes | — | MCP + Skills |
diff --git a/gitnexus/src/cli/augment.ts b/gitnexus/src/cli/augment.ts
index 553e3f591..a97f6e23c 100644
--- a/gitnexus/src/cli/augment.ts
+++ b/gitnexus/src/cli/augment.ts
@@ -2,7 +2,7 @@
  * Augment CLI Command
  *
  * Fast-path command for platform hooks.
- * Shells out from Claude Code PreToolUse / Cursor beforeShellExecution hooks.
+ * Shells out from Claude Code PreToolUse / Cursor postToolUse hooks.
  *
  * Usage: gitnexus augment <pattern>
  * Returns enriched text to stdout.
diff --git a/gitnexus/src/core/augmentation/engine.ts b/gitnexus/src/core/augmentation/engine.ts
index f97415cc9..42087e4b0 100644
--- a/gitnexus/src/core/augmentation/engine.ts
+++ b/gitnexus/src/core/augmentation/engine.ts
@@ -2,8 +2,8 @@
  * Augmentation Engine
  *
  * Lightweight, fast-path enrichment of search patterns with knowledge graph context.
- * Designed to be called from platform hooks (Claude Code PreToolUse, Cursor beforeShellExecution)
- * when an agent runs grep/glob/search.
+ * Designed to be called from platform hooks (Claude Code PreToolUse, Cursor postToolUse)
+ * when an agent runs grep/glob/read/search.
  *
  * Performance target: <500ms cold start, <200ms warm.
  *
diff --git a/gitnexus/test/unit/cursor-hook.test.ts b/gitnexus/test/unit/cursor-hook.test.ts
new file mode 100644
index 000000000..f0d875dee
--- /dev/null
+++ b/gitnexus/test/unit/cursor-hook.test.ts
@@ -0,0 +1,458 @@
+/**
+ * Regression Tests: Cursor postToolUse Hook
+ *
+ * Tests the hook script at gitnexus-cursor-integration/hooks/gitnexus-hook.cjs
+ * which runs as a Cursor 2.4 postToolUse hook.
+ *
+ * Covers:
+ * - extractPattern: pattern extraction from Grep/Read/Shell tool inputs
+ * - findGitNexusDir: .gitnexus directory discovery (shared with Claude hook)
+ * - cwd validation: rejects relative paths
+ * - shell injection: verifies no `shell: true` in spawnSync calls
+ * - cross-platform: Windows .cmd extension handling
+ * - output shape: top-level `additional_context` (NOT Claude's `hookSpecificOutput.additionalContext`)
+ * - hooks.json wiring matches the script's actual handlers
+ *
+ * Cursor hooks reach the augment CLI only when cwd is inside an indexed
+ * repo, so behavior tests stick to early-exit paths to avoid spawning
+ * `npx gitnexus`.
+ */
+import { describe, it, expect, beforeAll, afterAll } from 'vitest';
+import { spawnSync } from 'child_process';
+import fs from 'fs';
+import path from 'path';
+import os from 'os';
+import { runHook } from '../utils/hook-test-helpers.js';
+
+// ─── Path to the Cursor hook + manifest ─────────────────────────────
+
+const CURSOR_HOOK = path.resolve(
+  __dirname,
+  '..',
+  '..',
+  '..',
+  'gitnexus-cursor-integration',
+  'hooks',
+  'gitnexus-hook.cjs',
+);
+const CURSOR_HOOKS_JSON = path.resolve(
+  __dirname,
+  '..',
+  '..',
+  '..',
+  'gitnexus-cursor-integration',
+  'hooks',
+  'hooks.json',
+);
+
+// ─── Cursor-specific output parser ──────────────────────────────────
+// Cursor postToolUse output shape: { "additional_context": "..." }
+
+function parseCursorOutput(stdout: string): { additional_context?: string } | null {
+  if (!stdout.trim()) return null;
+  try {
+    return JSON.parse(stdout.trim());
+  } catch {
+    return null;
+  }
+}
+
+// ─── Test fixtures ──────────────────────────────────────────────────
+
+let tmpDir: string;
+
+beforeAll(() => {
+  tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'gitnexus-cursor-hook-test-'));
+  spawnSync('git', ['init'], { cwd: tmpDir, stdio: 'pipe' });
+  spawnSync('git', ['config', 'user.email', 'test@test.com'], { cwd: tmpDir, stdio: 'pipe' });
+  spawnSync('git', ['config', 'user.name', 'Test'], { cwd: tmpDir, stdio: 'pipe' });
+});
+
+afterAll(() => {
+  fs.rmSync(tmpDir, { recursive: true, force: true });
+});
+
+// ─── Manifest + hook file presence ───────────────────────────────────
+
+describe('Cursor integration files', () => {
+  it('hook script exists', () => {
+    expect(fs.existsSync(CURSOR_HOOK)).toBe(true);
+  });
+
+  it('hooks.json exists', () => {
+    expect(fs.existsSync(CURSOR_HOOKS_JSON)).toBe(true);
+  });
+
+  it('legacy augment-shell.sh has been removed', () => {
+    const legacy = path.resolve(
+      __dirname,
+      '..',
+      '..',
+      '..',
+      'gitnexus-cursor-integration',
+      'hooks',
+      'augment-shell.sh',
+    );
+    expect(fs.existsSync(legacy)).toBe(false);
+  });
+});
+
+// ─── hooks.json wiring ──────────────────────────────────────────────
+
+describe('hooks.json wiring', () => {
+  const manifest = JSON.parse(fs.readFileSync(CURSOR_HOOKS_JSON, 'utf-8'));
+
+  it('declares version 1', () => {
+    expect(manifest.version).toBe(1);
+  });
+
+  it('registers a postToolUse hook (not legacy beforeShellExecution)', () => {
+    expect(manifest.hooks.postToolUse).toBeDefined();
+    expect(Array.isArray(manifest.hooks.postToolUse)).toBe(true);
+    expect(manifest.hooks.beforeShellExecution).toBeUndefined();
+  });
+
+  it('matches Shell, Read, and Grep tools', () => {
+    const matcher: string = manifest.hooks.postToolUse[0].matcher;
+    expect(matcher).toMatch(/Shell/);
+    expect(matcher).toMatch(/Read/);
+    expect(matcher).toMatch(/Grep/);
+  });
+
+  it('points command at the new Node hook', () => {
+    const command: string = manifest.hooks.postToolUse[0].command;
+    expect(command).toContain('gitnexus-hook.cjs');
+    expect(command).not.toContain('augment-shell.sh');
+  });
+
+  it('declares timeout in seconds (not milliseconds)', () => {
+    // Cursor's `timeout` field is in seconds per
+    // https://cursor.com/docs/agent/hooks. Regression guard: a value of
+    // 1000+ here would be a >16-minute timeout, almost certainly a ms/s mixup.
+    const timeout: number = manifest.hooks.postToolUse[0].timeout;
+    expect(typeof timeout).toBe('number');
+    expect(timeout).toBeGreaterThan(0);
+    expect(timeout).toBeLessThan(120);
+  });
+});
+
+// ─── Source code regressions ────────────────────────────────────────
+
+describe('Cursor hook source regressions', () => {
+  const source = fs.readFileSync(CURSOR_HOOK, 'utf-8');
+
+  it('does not pass shell: true to spawnSync', () => {
+    const lines = source.split('\n');
+    for (let i = 0; i < lines.length; i++) {
+      const line = lines[i];
+      if (line.trim().startsWith('//') || line.trim().startsWith('*')) continue;
+      if (/shell:\s*(true|isWin)/.test(line)) {
+        throw new Error(`Cursor hook line ${i + 1} has shell injection risk: ${line.trim()}`);
+      }
+    }
+  });
+
+  it('uses npx.cmd for Windows', () => {
+    expect(source).toContain('npx.cmd');
+  });
+
+  it('validates cwd is an absolute path', () => {
+    expect(source).toMatch(/path\.isAbsolute\(cwd\)/);
+  });
+
+  it('truncates debug error messages to 200 chars', () => {
+    expect(source).toContain('.slice(0, 200)');
+  });
+
+  it('emits Cursor-shape additional_context (not Claude hookSpecificOutput)', () => {
+    expect(source).toContain('additional_context');
+    expect(source).not.toContain('hookSpecificOutput');
+    expect(source).not.toContain('hookEventName');
+  });
+
+  it('rejects patterns shorter than 3 chars', () => {
+    expect(source).toMatch(/length\s*>=\s*3/);
+  });
+
+  it('passes pattern after end-of-options marker (--)', () => {
+    // Regression for #200 — augment patterns starting with `-` would
+    // otherwise be parsed as CLI flags by the gitnexus CLI.
+    expect(source).toMatch(/'augment',\s*'--',\s*pattern/);
+  });
+
+  it('gates on a non-global .gitnexus directory before invoking the CLI', () => {
+    expect(source).toContain('findGitNexusDir');
+    expect(source).toContain('isGlobalRegistryDir');
+  });
+
+  it('handles linked git worktrees via git rev-parse --git-common-dir', () => {
+    expect(source).toContain('--git-common-dir');
+  });
+});
+
+// ─── extractPattern coverage (source-level) ─────────────────────────
+
+describe('Cursor hook extractPattern coverage', () => {
+  const source = fs.readFileSync(CURSOR_HOOK, 'utf-8');
+
+  it("handles 'grep' tool (Cursor matcher: Grep)", () => {
+    expect(source).toMatch(/t === 'grep'/);
+  });
+
+  it('probes a wide alias set for Grep query field (Cursor contract not formally specified)', () => {
+    // Cursor 2.4 docs at https://cursor.com/docs/agent/hooks list the
+    // matchers but not the per-tool tool_input field names. If Cursor
+    // changes the contract, we want the hook to still extract *something*
+    // — these aliases plus the longest-string fallback give us coverage.
+    for (const alias of ['query', 'pattern', 'regex', 'q', 'search', 'searchQuery']) {
+      expect(source).toContain(`toolInput.${alias}`);
+    }
+    expect(source).toContain('pickLongestStringValue');
+  });
+
+  it("handles 'read' tool (Cursor matcher: Read)", () => {
+    expect(source).toMatch(/t === 'read'/);
+    for (const alias of ['target_file', 'file_path', 'filePath', 'path', 'file']) {
+      expect(source).toContain(`toolInput.${alias}`);
+    }
+  });
+
+  it("handles 'shell' tool (Cursor matcher: Shell)", () => {
+    expect(source).toMatch(/t === 'shell'/);
+    expect(source).toMatch(/\\brg\\b\|\\bgrep\\b/);
+  });
+
+  it('logs raw payload to stderr when GITNEXUS_DEBUG is set (for contract diagnostics)', () => {
+    expect(source).toContain('GITNEXUS_DEBUG');
+    expect(source).toContain('GitNexus Cursor hook stdin:');
+  });
+});
+
+// ─── Behavior: graceful no-op paths (no augment CLI invocation) ─────
+
+describe('Cursor hook behavior — early-exit paths', () => {
+  it('exits cleanly on empty stdin', () => {
+    const result = spawnSync(process.execPath, [CURSOR_HOOK], {
+      input: '',
+      encoding: 'utf-8',
+      timeout: 10000,
+      stdio: ['pipe', 'pipe', 'pipe'],
+    });
+    expect(result.status).toBe(0);
+    expect(result.stdout.trim()).toBe('');
+  });
+
+  it('exits cleanly on invalid JSON stdin', () => {
+    const result = spawnSync(process.execPath, [CURSOR_HOOK], {
+      input: 'not json at all',
+      encoding: 'utf-8',
+      timeout: 10000,
+      stdio: ['pipe', 'pipe', 'pipe'],
+    });
+    expect(result.status).toBe(0);
+    expect(result.stdout.trim()).toBe('');
+  });
+
+  it('produces no output when cwd is relative', () => {
+    const result = runHook(CURSOR_HOOK, {
+      tool_name: 'Grep',
+      tool_input: { query: 'validateUser' },
+      cwd: 'relative/path',
+    });
+    expect(result.stdout.trim()).toBe('');
+    expect(result.status).toBe(0);
+  });
+
+  it('produces no output when cwd has no .gitnexus dir', () => {
+    const result = runHook(CURSOR_HOOK, {
+      tool_name: 'Grep',
+      tool_input: { query: 'validateUser' },
+      cwd: tmpDir,
+    });
+    expect(result.stdout.trim()).toBe('');
+    expect(result.status).toBe(0);
+  });
+
+  it('produces no output for unknown tool names', () => {
+    const result = runHook(CURSOR_HOOK, {
+      tool_name: 'TotallyMadeUpTool',
+      tool_input: { foo: 'bar' },
+      cwd: tmpDir,
+    });
+    expect(result.stdout.trim()).toBe('');
+    expect(result.status).toBe(0);
+  });
+
+  it('produces no output for Shell commands without rg/grep', () => {
+    const result = runHook(CURSOR_HOOK, {
+      tool_name: 'Shell',
+      tool_input: { command: 'ls -la' },
+      cwd: tmpDir,
+    });
+    expect(result.stdout.trim()).toBe('');
+    expect(result.status).toBe(0);
+  });
+
+  it('produces no output for Grep with a 2-char query', () => {
+    const result = runHook(CURSOR_HOOK, {
+      tool_name: 'Grep',
+      tool_input: { query: 'is' },
+      cwd: tmpDir,
+    });
+    expect(result.stdout.trim()).toBe('');
+    expect(result.status).toBe(0);
+  });
+
+  it('produces no output for Read whose basename has no identifier chars', () => {
+    const result = runHook(CURSOR_HOOK, {
+      tool_name: 'Read',
+      tool_input: { target_file: '/tmp/--.md' },
+      cwd: tmpDir,
+    });
+    expect(result.stdout.trim()).toBe('');
+    expect(result.status).toBe(0);
+  });
+
+  it('produces no output for Read with no file path', () => {
+    const result = runHook(CURSOR_HOOK, {
+      tool_name: 'Read',
+      tool_input: {},
+      cwd: tmpDir,
+    });
+    expect(result.stdout.trim()).toBe('');
+    expect(result.status).toBe(0);
+  });
+
+  it('treats tool_name case-insensitively (Grep vs grep)', () => {
+    // Both should reach the same handler — and both should early-exit silently
+    // because tmpDir has no .gitnexus.
+    for (const toolName of ['Grep', 'grep', 'GREP']) {
+      const result = runHook(CURSOR_HOOK, {
+        tool_name: toolName,
+        tool_input: { query: 'validateUser' },
+        cwd: tmpDir,
+      });
+      expect(result.stdout.trim()).toBe('');
+      expect(result.status).toBe(0);
+    }
+  });
+});
+
+// ─── Behavior: GITNEXUS_DEBUG payload logging ────────────────────────
+
+describe('Cursor hook debug logging', () => {
+  it('echoes the payload to stderr only when GITNEXUS_DEBUG is set', () => {
+    const payload = {
+      tool_name: 'Grep',
+      tool_input: { query: 'validateUser' },
+      cwd: tmpDir,
+    };
+
+    // GITNEXUS_DEBUG unset → stderr quiet.
+    const quiet = spawnSync(process.execPath, [CURSOR_HOOK], {
+      input: JSON.stringify(payload),
+      encoding: 'utf-8',
+      timeout: 10000,
+      stdio: ['pipe', 'pipe', 'pipe'],
+      env: { ...process.env, GITNEXUS_DEBUG: '' },
+    });
+    expect(quiet.status).toBe(0);
+    expect(quiet.stderr).not.toContain('GitNexus Cursor hook stdin');
+
+    // GITNEXUS_DEBUG=1 → payload echoed to stderr (stdout still empty for
+    // unindexed cwd, so the hook output contract is preserved).
+    const verbose = spawnSync(process.execPath, [CURSOR_HOOK], {
+      input: JSON.stringify(payload),
+      encoding: 'utf-8',
+      timeout: 10000,
+      stdio: ['pipe', 'pipe', 'pipe'],
+      env: { ...process.env, GITNEXUS_DEBUG: '1' },
+    });
+    expect(verbose.status).toBe(0);
+    expect(verbose.stderr).toContain('GitNexus Cursor hook stdin');
+    expect(verbose.stderr).toContain('"tool_name":"Grep"');
+    expect(verbose.stdout.trim()).toBe('');
+  });
+});
+
+// ─── Documented contract behavior (extractPattern via the live hook) ─
+
+describe('Shell quoted-pattern parser limitations (documented)', () => {
+  // The Shell parser cannot reconstruct shell quoting. These tests pin the
+  // current behavior so a future "fix" doesn't silently change extraction
+  // — and so users diagnosing a noisy/missed pattern can find the behavior
+  // documented in tests.
+  //
+  // We can't observe the extracted pattern directly without an indexed
+  // repo, but we *can* confirm the hook reaches the augment-call path
+  // (vs. early-exiting) by checking exit status + clean stdout for cases
+  // where parseRgGrepPattern would yield a >=3-char token.
+
+  it('quoted multi-word `rg "User Service"` extracts the first word only', () => {
+    const result = runHook(CURSOR_HOOK, {
+      tool_name: 'Shell',
+      tool_input: { command: 'rg "User Service" src/' },
+      cwd: tmpDir, // no .gitnexus → exits early after extract
+    });
+    expect(result.status).toBe(0);
+    expect(result.stdout.trim()).toBe('');
+  });
+
+  it('single-token quoted `rg "validateUser"` works as expected', () => {
+    const result = runHook(CURSOR_HOOK, {
+      tool_name: 'Shell',
+      tool_input: { command: 'rg "validateUser"' },
+      cwd: tmpDir,
+    });
+    expect(result.status).toBe(0);
+    expect(result.stdout.trim()).toBe('');
+  });
+});
+
+// ─── Install docs ─────────────────────────────────────────────────────
+
+describe('Cursor integration install docs', () => {
+  const integrationReadme = path.resolve(
+    __dirname,
+    '..',
+    '..',
+    '..',
+    'gitnexus-cursor-integration',
+    'README.md',
+  );
+
+  it('install README exists', () => {
+    expect(fs.existsSync(integrationReadme)).toBe(true);
+  });
+
+  it('install README documents the hook install path', () => {
+    const body = fs.readFileSync(integrationReadme, 'utf-8');
+    expect(body).toContain('.cursor/hooks.json');
+    expect(body).toContain('hooks/gitnexus-hook.cjs');
+    expect(body).toContain('Hook install');
+  });
+
+  it('install README documents GITNEXUS_DEBUG for payload diagnostics', () => {
+    const body = fs.readFileSync(integrationReadme, 'utf-8');
+    expect(body).toContain('GITNEXUS_DEBUG');
+  });
+});
+
+// ─── Output parser sanity (synthetic JSON) ──────────────────────────
+
+describe('parseCursorOutput', () => {
+  it('parses a well-formed { additional_context } payload', () => {
+    const parsed = parseCursorOutput('{"additional_context":"hello"}');
+    expect(parsed).not.toBeNull();
+    expect(parsed?.additional_context).toBe('hello');
+  });
+
+  it('returns null on empty stdout', () => {
+    expect(parseCursorOutput('')).toBeNull();
+    expect(parseCursorOutput('   \n')).toBeNull();
+  });
+
+  it('returns null on malformed JSON', () => {
+    expect(parseCursorOutput('not json')).toBeNull();
+  });
+});