diff --git a/README.md b/README.md
index 896afef..76d44d8 100644
--- a/README.md
+++ b/README.md
@@ -38,7 +38,32 @@ QRコード/リンクのアクセスを記録し、リダイレクトするた
 | Worker URL | `https://trackinglink.nutfes-nutmeg9488.workers.dev` |
 | Cloudflare Workerプロジェクト名 | `trackinglink` |
 | D1データベース名 | `trackinglink-db` |
-| デプロイ方法 | Cloudflareダッシュボード連携(Workers Builds)。`main`ブランチにpushすると自動デプロイ |
+| デプロイ方法 | ローカルから `pnpm deploy:api` を実行して手動デプロイ |
+
+### デプロイ
+
+リポジトリのルートで以下を実行します。
+
+```bash
+pnpm deploy:api
+```
+
+これは [`packages/api/scripts/deploy.mjs`](packages/api/scripts/deploy.mjs) を経由して `wrangler deploy --minify` を実行し、
+あわせて**現在のコミットを `GIT_SHA` としてWorkerに埋め込みます**。作業ツリーに未コミットの変更がある場合は
+`c7d34cd-dirty` のように `-dirty` が付き、稼働中のコードがそのコミットと同一でないことが分かるようになっています。
+
+### ヘルスチェック
+
+| エンドポイント | 内容 |
+| --- | --- |
+| `GET /healthz` | Liveness。DBには触れず `{"ok":true,"version":"<GIT_SHA>"}` を返す。`version` で稼働中のコミットを確認できる(未設定時は `dev`) |
+| `GET /readyz` | Readiness。`SELECT 1` でD1への到達性まで確認し、失敗時は `503` を返す |
+
+外部監視サービス(UptimeRobotなど)は `/healthz` に向けてください。`/readyz` を1分間隔で叩いても
+約1,440読み取り/日で、D1の500万読み取り/日に対して無視できる量です。
+
+**`GET /` を監視先にしないこと。** ここはQRコードのリダイレクト用で、`?id=` が無いと404を返すため、
+監視に使うとアラートが鳴り続けます。
 
 APIの設定・認証情報は以下の2種類に分かれています。
 
diff --git a/packages/api/package.json b/packages/api/package.json
index 304aee1..6c32eeb 100644
--- a/packages/api/package.json
+++ b/packages/api/package.json
@@ -10,7 +10,7 @@
 	},
 	"scripts": {
 		"dev": "wrangler dev",
-		"deploy": "wrangler deploy --minify",
+		"deploy": "node scripts/deploy.mjs",
 		"typecheck": "tsc --noEmit",
 		"cf-typegen": "wrangler types --env-interface CloudflareBindings",
 		"db:apply:local": "wrangler d1 execute trackinglink-db --local --file=./schema.sql",
diff --git a/packages/api/scripts/deploy.mjs b/packages/api/scripts/deploy.mjs
new file mode 100644
index 0000000..b6334f1
--- /dev/null
+++ b/packages/api/scripts/deploy.mjs
@@ -0,0 +1,86 @@
+// Deploys the Worker with the current commit baked in as GIT_SHA.
+//
+// Exists because `/healthz` reports `version: c.env.GIT_SHA ?? 'dev'`, and until
+// this script there was nothing setting GIT_SHA — so production answered
+// `{"ok":true,"version":"dev"}` forever and the health check could not tell you
+// which commit was actually running. Knowing that is the entire point of putting
+// a version in a liveness probe; see docs/load-test-report-2026-07-27.md §5.4.
+//
+// Why a Node script rather than `wrangler deploy --var GIT_SHA:$(git rev-parse ...)`
+// in package.json: pnpm runs scripts through cmd.exe on Windows, where `$(...)`
+// is not command substitution but a literal string. The var would have been set
+// to the text "$(git rev-parse --short HEAD)" on exactly the machine this project
+// is deployed from.
+//
+// Usage:
+//   pnpm deploy                 (from packages/api)
+//   pnpm deploy:api             (from the repository root)
+//   pnpm deploy -- --dry-run    (extra arguments are passed through to wrangler)
+import { spawnSync } from 'node:child_process';
+import { join } from 'node:path';
+
+/**
+ * Windows needs `shell: true` to launch wrangler.CMD at all. Copied from
+ * scripts/backfill-short-codes.mjs so both scripts fail the same way.
+ */
+const useShell = process.platform === 'win32';
+
+// join() rather than a slash-separated literal: with shell:true the command runs
+// through cmd.exe, which does not accept forward slashes as path separators and
+// answers `'node_modules' is not recognized`.
+const wranglerBin = join(
+	'node_modules',
+	'.bin',
+	useShell ? 'wrangler.CMD' : 'wrangler',
+);
+
+function git(args) {
+	const result = spawnSync('git', args, { encoding: 'utf8', shell: useShell });
+	if (result.status !== 0) return null;
+	return (result.stdout ?? '').trim();
+}
+
+/**
+ * The identifier `/healthz` will report.
+ *
+ * `-dirty` is not decoration. This deploys from a laptop rather than from CI, so
+ * shipping uncommitted work is normal and a bare SHA would be a claim the running
+ * code equals that commit — which is the one thing you must not get wrong while
+ * reading a health check during an incident.
+ *
+ * Returns null when git cannot answer (no git, no repository, no commits). The
+ * deploy still goes ahead without the variable and `/healthz` falls back to
+ * "dev", because refusing to deploy over a missing version label would be worse
+ * than deploying with the label this project already had.
+ */
+function resolveVersion() {
+	const sha = git(['rev-parse', '--short', 'HEAD']);
+	if (!sha) return null;
+	const status = git(['status', '--porcelain']);
+	return status ? `${sha}-dirty` : sha;
+}
+
+const passthrough = process.argv.slice(2);
+const version = resolveVersion();
+const argv = ['deploy', '--minify'];
+
+if (version) {
+	argv.push('--var', `GIT_SHA:${version}`);
+	console.log(`Deploying as GIT_SHA=${version}`);
+} else {
+	console.warn(
+		'Could not determine the commit; deploying without GIT_SHA. /healthz will report "dev".',
+	);
+}
+
+// `--var` merges with the `vars` block in wrangler.jsonc rather than replacing
+// it, so FALLBACK_DESTINATIONS and friends survive. Verified with
+// `wrangler deploy --dry-run`, which lists every binding it would upload.
+argv.push(...passthrough);
+
+const result = spawnSync(wranglerBin, argv, {
+	stdio: 'inherit',
+	shell: useShell,
+});
+
+process.exit(result.status ?? 1);