diff --git a/package-lock.json b/package-lock.json
index 828f7b2f..fda883b5 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -14,6 +14,7 @@
         "awilix": "^12.1.0",
         "chalk": "^5.3.0",
         "commander": "^11.1.0",
+        "dotenv": "^17.3.1",
         "prompts": "^2.4.2"
       },
       "bin": {
@@ -2960,6 +2961,18 @@
         "node": ">=8"
       }
     },
+    "node_modules/dotenv": {
+      "version": "17.3.1",
+      "resolved": "https://registry.npmjs.org/dotenv/-/dotenv-17.3.1.tgz",
+      "integrity": "sha512-IO8C/dzEb6O3F9/twg6ZLXz164a2fhTnEWb95H23Dm4OuN+92NmEAlTrupP9VW6Jm3sO26tQlqyvyi4CsnY9GA==",
+      "license": "BSD-2-Clause",
+      "engines": {
+        "node": ">=12"
+      },
+      "funding": {
+        "url": "https://dotenvx.com"
+      }
+    },
     "node_modules/dunder-proto": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/dunder-proto/-/dunder-proto-1.0.1.tgz",
diff --git a/package.json b/package.json
index 4e662c4d..e15d736f 100644
--- a/package.json
+++ b/package.json
@@ -45,6 +45,7 @@
     "awilix": "^12.1.0",
     "chalk": "^5.3.0",
     "commander": "^11.1.0",
+    "dotenv": "^17.3.1",
     "prompts": "^2.4.2"
   },
   "devDependencies": {
diff --git a/src/commands/hook.ts b/src/commands/hook.ts
index e5cf2c4e..25d3e2f4 100644
--- a/src/commands/hook.ts
+++ b/src/commands/hook.ts
@@ -10,6 +10,9 @@
  *   git-mem hook prompt-submit
  */
 
+import { join } from 'path';
+import { execFileSync } from 'child_process';
+import { config as loadEnv } from 'dotenv';
 import { createContainer } from '../infrastructure/di';
 import { readStdin } from '../hooks/utils/stdin';
 import { setupShutdown } from '../hooks/utils/shutdown';
@@ -100,6 +103,22 @@ export function buildEvent(eventType: HookEventType, input: IHookInput): HookEve
   }
 }
 
+/**
+ * Find git repository root from a working directory.
+ * Returns cwd if git command fails (graceful fallback).
+ */
+function findGitRoot(cwd: string): string {
+  try {
+    return execFileSync('git', ['rev-parse', '--show-toplevel'], {
+      cwd,
+      encoding: 'utf8',
+      stdio: ['pipe', 'pipe', 'pipe'],
+    }).trim();
+  } catch {
+    return cwd;
+  }
+}
+
 /** Stderr labels per event for user-facing messages. */
 const STDERR_LABELS: Record<HookEventType, { success: string; prefix: string }> = {
   'session:start': { success: 'Memory loaded.', prefix: 'Memory loaded' },
@@ -120,7 +139,13 @@ export async function hookCommand(eventName: string, _logger?: ILogger): Promise
 
   try {
     const input = await readStdin<IHookInput>();
-    const config = loadHookConfig(input.cwd);
+    const cwd = input.cwd ?? process.cwd();
+    const repoRoot = findGitRoot(cwd);
+
+    // Load .env from repository root for API keys (e.g., ANTHROPIC_API_KEY)
+    loadEnv({ path: join(repoRoot, '.env'), quiet: true });
+
+    const config = loadHookConfig(repoRoot);
 
     if (!isEventEnabled(config.hooks, eventName)) {
       clearTimeout(timer);