Relax Elixir version constraint to ~> 1.17 and add CI

.github/workflows/ci.yml

@@ -0,0 +1,82 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+    name: Elixir ${{ matrix.elixir }} / OTP ${{ matrix.otp }}
+    runs-on: ubuntu-latest
+
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - elixir: "1.17"
+            otp: "26"
+          - elixir: "1.18"
+            otp: "27"
+          - elixir: "1.19"
+            otp: "28"
+
+    env:
+      MIX_ENV: test
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: erlef/setup-beam@v1
+        with:
+          elixir-version: ${{ matrix.elixir }}
+          otp-version: ${{ matrix.otp }}
+
+      - uses: actions/cache@v4
+        with:
+          path: |
+            deps
+            _build
+          key: ${{ runner.os }}-mix-${{ matrix.elixir }}-${{ matrix.otp }}-${{ hashFiles('mix.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-mix-${{ matrix.elixir }}-${{ matrix.otp }}-
+
+      - run: mix deps.get
+
+      - run: mix compile --warnings-as-errors
+
+      - run: mix test
+
+  lint:
+    name: Lint
+    runs-on: ubuntu-latest
+
+    env:
+      MIX_ENV: dev
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: erlef/setup-beam@v1
+        with:
+          elixir-version: "1.19"
+          otp-version: "28"
+
+      - uses: actions/cache@v4
+        with:
+          path: |
+            deps
+            _build
+          key: ${{ runner.os }}-mix-lint-1.19-28-${{ hashFiles('mix.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-mix-lint-1.19-28-
+
+      - run: mix deps.get
+
+      - run: mix format --check-formatted
+
+      - run: mix credo --strict

CHANGELOG.md

@@ -7,6 +7,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+- Relaxed Elixir version constraint from `~> 1.19` to `~> 1.17` to support projects on Elixir 1.17 and 1.18
+
+### Added
+- GitHub Actions CI with matrix testing across Elixir 1.17/OTP 26, 1.18/OTP 27, and 1.19/OTP 28
+
 ## [0.1.0] - 2025-11-29
 
 ### Added

devenv.yaml

@@ -1,3 +1,8 @@
 inputs:
+  git-hooks:
+    url: github:cachix/git-hooks.nix
+    inputs:
+      nixpkgs:
+        follows: nixpkgs
   nixpkgs:
     url: github:cachix/devenv-nixpkgs/rolling

mix.exs

@@ -8,7 +8,7 @@ defmodule Langfuse.MixProject do
     [
       app: :langfuse,
       version: @version,
-      elixir: "~> 1.19",
+      elixir: "~> 1.17",
       start_permanent: Mix.env() == :prod,
       deps: deps(),
       elixirc_paths: elixirc_paths(Mix.env()),