From c5f34ec1c3d2237813bfe7ed2dd44a212b979cc6 Mon Sep 17 00:00:00 2001
From: marcopiraccini <marco.piraccini@gmail.com>
Date: Thu, 28 May 2026 18:18:28 +0200
Subject: [PATCH 1/2] types

Signed-off-by: marcopiraccini <marco.piraccini@gmail.com>
---
 .github/workflows/ci.yml |  2 ++
 index.d.ts               | 40 ++++++++++++++++++++++++++++++++++++++++
 package.json             |  5 ++++-
 test/types.test-d.ts     | 36 ++++++++++++++++++++++++++++++++++++
 tsconfig.json            | 11 +++++++++++
 5 files changed, 93 insertions(+), 1 deletion(-)
 create mode 100644 index.d.ts
 create mode 100644 test/types.test-d.ts
 create mode 100644 tsconfig.json

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 3b050e1..8404efe 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -63,3 +63,5 @@ jobs:
         run: npm install
       - name: Run linter
         run: npm run lint
+      - name: Type check
+        run: npm run test:types
diff --git a/index.d.ts b/index.d.ts
new file mode 100644
index 0000000..1838e79
--- /dev/null
+++ b/index.d.ts
@@ -0,0 +1,40 @@
+declare function createLeaderElector (
+  options: createLeaderElector.LeaderElectorOptions
+): createLeaderElector.LeaderElector
+
+declare namespace createLeaderElector {
+  export interface Pool {
+    connect (): Promise<unknown>
+    query (text: string, ...args: unknown[]): Promise<unknown>
+  }
+
+  export interface Logger {
+    info: (...args: unknown[]) => void
+    debug: (...args: unknown[]) => void
+    warn: (...args: unknown[]) => void
+    error: (...args: unknown[]) => void
+  }
+
+  export interface NotificationChannel<TPayload = unknown> {
+    channel: string
+    onNotification: (payload: TPayload) => void | Promise<void>
+  }
+
+  export interface LeaderElectorOptions {
+    pool: Pool
+    lock: number
+    poll?: number
+    channels?: NotificationChannel[]
+    log?: Logger
+    onLeadershipChange?: ((isLeader: boolean) => void) | null
+  }
+
+  export interface LeaderElector {
+    start (): Promise<void>
+    stop (): Promise<void>
+    notify (payload: unknown, channelName: string): Promise<void>
+    isLeader (): boolean
+  }
+}
+
+export = createLeaderElector
diff --git a/package.json b/package.json
index c375948..c5a8905 100644
--- a/package.json
+++ b/package.json
@@ -3,8 +3,10 @@
   "version": "0.2.0",
   "description": "PostgreSQL advisory lock-based leader election with notification channels",
   "main": "index.js",
+  "types": "index.d.ts",
   "scripts": {
     "test": "node --test test/*.test.js",
+    "test:types": "tsc -p tsconfig.json",
     "lint": "standard ."
   },
   "dependencies": {
@@ -12,7 +14,8 @@
     "pino": "^10.3.1"
   },
   "devDependencies": {
-    "standard": "^17.1.2"
+    "standard": "^17.1.2",
+    "typescript": "^5.9.3"
   },
   "engines": {
     "node": ">=22.0.0"
diff --git a/test/types.test-d.ts b/test/types.test-d.ts
new file mode 100644
index 0000000..95ff3de
--- /dev/null
+++ b/test/types.test-d.ts
@@ -0,0 +1,36 @@
+import createLeaderElector = require('../index')
+
+const fakePool: createLeaderElector.Pool = {
+  connect: async () => ({}),
+  query: async () => ({})
+}
+
+const elector: createLeaderElector.LeaderElector = createLeaderElector({
+  pool: fakePool,
+  lock: 42,
+  poll: 1000,
+  channels: [
+    {
+      channel: 'deferred_messages',
+      onNotification: async (payload: unknown) => { void payload }
+    }
+  ],
+  log: {
+    info: () => {},
+    debug: () => {},
+    warn: () => {},
+    error: () => {}
+  },
+  onLeadershipChange: (isLeader: boolean) => { void isLeader }
+})
+
+const _minimal: createLeaderElector.LeaderElector = createLeaderElector({
+  pool: fakePool,
+  lock: 1
+})
+
+const _start: Promise<void> = elector.start()
+const _stop: Promise<void> = elector.stop()
+const _notify: Promise<void> = elector.notify({ id: 1 }, 'channel')
+const _isLeader: boolean = elector.isLeader()
+void _minimal; void _start; void _stop; void _notify; void _isLeader
diff --git a/tsconfig.json b/tsconfig.json
new file mode 100644
index 0000000..164cfa1
--- /dev/null
+++ b/tsconfig.json
@@ -0,0 +1,11 @@
+{
+  "compilerOptions": {
+    "module": "nodenext",
+    "moduleResolution": "nodenext",
+    "target": "esnext",
+    "strict": true,
+    "noEmit": true,
+    "skipLibCheck": true
+  },
+  "include": ["index.d.ts", "test/types.test-d.ts"]
+}

From dd76d0a55661c9807b16cadd88960708a42e1cc9 Mon Sep 17 00:00:00 2001
From: marcopiraccini <marco.piraccini@gmail.com>
Date: Thu, 28 May 2026 18:19:56 +0200
Subject: [PATCH 2/2] types

Signed-off-by: marcopiraccini <marco.piraccini@gmail.com>
---
 .github/workflows/ci.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8404efe..1defccf 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -21,7 +21,7 @@ jobs:
     timeout-minutes: 10
     strategy:
       matrix:
-        node: [22, 24]
+        node: [22, 24, 26]
     services:
       postgres:
         image: postgres:17