diff --git a/.dockerignore b/.dockerignore
new file mode 100644
index 0000000..14472c8
--- /dev/null
+++ b/.dockerignore
@@ -0,0 +1,6 @@
+.git
+.gitea
+var/
+.env.local
+.env.*.local
+docker-compose.override.yml
diff --git a/.gitea/workflows/docker-publish.yml b/.gitea/workflows/docker-publish.yml
new file mode 100644
index 0000000..fbfa43f
--- /dev/null
+++ b/.gitea/workflows/docker-publish.yml
@@ -0,0 +1,70 @@
+# Builds and pushes a multi-arch Docker image to the Gitea container registry
+# whenever a semver tag (v*.*.*) is pushed.
+#
+# One-time setup required:
+#   1. Create a Gitea token with "package:write" scope.
+#   2. Add it as a repository secret named GITEA_TOKEN
+#      (Repository → Settings → Secrets → Actions).
+#
+# After a successful run the image is available at:
+#   <your-gitea-host>/<owner>/<repo>:<version>
+
+name: Docker Publish
+
+on:
+  push:
+    tags:
+      - 'v*.*.*'
+
+jobs:
+  build-push:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      # Strip the protocol from the server URL to get the registry hostname.
+      # e.g. https://gitea.example.com → gitea.example.com
+      - name: Derive registry hostname
+        run: |
+          echo "REGISTRY=$(echo '${{ gitea.server_url }}' | sed 's|https://||;s|http://||')" >> $GITHUB_ENV
+
+      # Generates OCI-compliant tags and labels from the git tag.
+      # v1.2.3 → image tags: 1.2.3 / 1.2 / 1
+      - name: Extract Docker metadata
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.REGISTRY }}/${{ gitea.repository }}
+          tags: |
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=semver,pattern={{major}}
+
+      # QEMU enables emulation of arm64 on the amd64 runner.
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+
+      # BuildKit driver required for multi-platform builds and layer caching.
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to Gitea registry
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ gitea.actor }}
+          password: ${{ secrets.GITEA_TOKEN }}
+
+      - name: Build and push
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          # Registry-based layer cache — survives between runs without a separate cache store.
+          cache-from: type=registry,ref=${{ env.REGISTRY }}/${{ gitea.repository }}:buildcache
+          cache-to: type=registry,ref=${{ env.REGISTRY }}/${{ gitea.repository }}:buildcache,mode=max
diff --git a/CLAUDE.md b/CLAUDE.md
index 4c892cb..8eb2b8d 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -118,20 +118,49 @@ Add to `.claude/settings.json` to run PHPUnit automatically after every file edi
 
 ## Docker
 
+### Development
+
+`docker-compose.override.yml` is picked up automatically and targets the `dev` stage (Xdebug + all deps, source mounted).
+
 ```bash
-# Build and run
+# Start dev container (override applied automatically)
 docker compose up -d --build
 
-# Force cache clear (clears the 1h filesystem cache)
+# Shell into the container to run commands
+docker compose exec graph sh
+
+# Run tests inside the container
+docker compose exec graph php bin/phpunit
+
+# Disable Xdebug for faster test runs
+XDEBUG_MODE=off docker compose up -d
+
+# Force cache clear
 docker compose exec graph rm -rf var/cache/*
 
 # View logs
 docker compose logs -f graph
 ```
 
-There is no `composer.lock` in the repo. If you add or change dependencies, run `composer install` locally and commit the resulting lock file — without it, Docker builds resolve versions fresh each time and may produce inconsistent results.
+**Xdebug:** listens on port `9003`. Configure your IDE to accept connections from Docker. On Linux `host.docker.internal` is resolved via `extra_hosts: host-gateway` in the override file.
 
-The Dockerfile runs `composer install --no-scripts` (skipping Symfony post-install scripts) then `composer dump-autoload --optimize --no-dev` in the final stage. If `bin/console` fails with a missing class error inside the container, the most likely cause is the absent lock file causing an incomplete dependency resolution.
+### Production
+
+Use only the base compose file to skip the dev override:
+
+```bash
+docker compose -f docker-compose.yml up -d --build
+```
+
+The `final` stage runs as a non-root `app` user and contains no Composer binary. The build pipeline is:
+
+```
+base → deps (composer install --no-dev)
+     → build (copy source + dump-autoload)
+     → final (copy vendor + source, chown app, USER app)
+```
+
+There is no `composer.lock` in the repo. If you add or change dependencies, run `composer install` locally and commit the resulting lock file — without it, Docker builds resolve versions fresh each time and may produce inconsistent results.
 
 ## Architecture
 
diff --git a/Dockerfile b/Dockerfile
index b80117d..8dc4ff9 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,19 +1,16 @@
 FROM php:8.3-cli-alpine AS base
 
-# Runtime dependencies
 RUN apk add --no-cache \
     curl \
     icu-libs \
     libzip \
     && docker-php-ext-install opcache
 
-# Composer
-COPY --from=composer:2 /usr/bin/composer /usr/bin/composer
-
 WORKDIR /app
 
-# ── deps stage ────────────────────────────────────────────────────────────────
+# ── deps stage (prod vendor) ───────────────────────────────────────────────────
 FROM base AS deps
+COPY --from=composer:2 /usr/bin/composer /usr/bin/composer
 COPY composer.json composer.lock* ./
 RUN composer install \
         --no-dev \
@@ -22,20 +19,39 @@ RUN composer install \
         --optimize-autoloader \
         --prefer-dist
 
-# ── final stage ───────────────────────────────────────────────────────────────
+# ── build stage (generate optimised classmap with source present) ──────────────
+FROM deps AS build
+COPY . .
+RUN composer dump-autoload --optimize --no-dev --no-interaction
+
+# ── dev stage (all deps + Xdebug, source is mounted at runtime) ───────────────
+FROM base AS dev
+COPY --from=composer:2 /usr/bin/composer /usr/bin/composer
+RUN apk add --no-cache ${PHPIZE_DEPS} linux-headers \
+    && pecl install xdebug \
+    && docker-php-ext-enable xdebug \
+    && apk del ${PHPIZE_DEPS}
+COPY docker/php/xdebug.ini /usr/local/etc/php/conf.d/docker-xdebug.ini
+COPY composer.json composer.lock* ./
+RUN composer install --no-scripts --no-interaction --prefer-dist
+EXPOSE 8080
+ENV APP_ENV=dev APP_DEBUG=1
+CMD ["php", "-S", "0.0.0.0:8080", "-t", "public", "public/index.php"]
+
+# ── final (prod) stage — no composer binary ────────────────────────────────────
 FROM base AS final
 
-COPY --from=deps /app/vendor /app/vendor
+RUN addgroup -S app && adduser -S -G app app
+
+COPY --from=build /app/vendor /app/vendor
 COPY . .
 
 RUN mkdir -p var/cache var/log \
-    && chmod -R 777 var \
-    && composer dump-autoload --optimize --no-dev
+    && chown -R app:app /app
+
+USER app
 
 EXPOSE 8080
+ENV APP_ENV=prod APP_DEBUG=0
 
-ENV APP_ENV=prod \
-    APP_DEBUG=0
-
-# Symfony's built-in dev server via PHP — fine for a single-purpose container
 CMD ["php", "-S", "0.0.0.0:8080", "-t", "public", "public/index.php"]
diff --git a/config/services.yaml b/config/services.yaml
new file mode 100644
index 0000000..7888e8b
--- /dev/null
+++ b/config/services.yaml
@@ -0,0 +1,31 @@
+services:
+    _defaults:
+        autowire: true
+        autoconfigure: true
+        public: false
+
+    App\:
+        resource: '../src/'
+        exclude:
+            - '../src/Kernel.php'
+
+    _instanceof:
+        App\Service\ProviderInterface:
+            tags: ['app.provider']
+
+    App\Service\GitHubProvider:
+        arguments:
+            $username: '%env(GITHUB_USER)%'
+            $token: '%env(GITHUB_TOKEN)%'
+
+    App\Service\GitLabProvider:
+        arguments:
+            $username: '%env(GITLAB_USER)%'
+            $token: '%env(GITLAB_TOKEN)%'
+            $baseUrl: '%env(GITLAB_URL)%'
+
+    App\Service\GiteaProvider:
+        arguments:
+            $username: '%env(GITEA_USER)%'
+            $token: '%env(GITEA_TOKEN)%'
+            $baseUrl: '%env(GITEA_URL)%'
diff --git a/docker-compose.override.yml b/docker-compose.override.yml
new file mode 100644
index 0000000..bce0fb4
--- /dev/null
+++ b/docker-compose.override.yml
@@ -0,0 +1,19 @@
+# Local development overrides — picked up automatically by `docker compose up`.
+# To run with production config only: docker compose -f docker-compose.yml up
+services:
+  graph:
+    build:
+      target: dev
+    volumes:
+      - .:/app
+      - /app/vendor        # keeps vendor from the dev image, not your local dir
+    environment:
+      APP_ENV: dev
+      APP_DEBUG: "1"
+      XDEBUG_MODE: "${XDEBUG_MODE:-debug}"
+      XDEBUG_CONFIG: "client_host=host.docker.internal"
+    # Makes host.docker.internal resolve correctly on Linux
+    extra_hosts:
+      - "host.docker.internal:host-gateway"
+    ports:
+      - "9003:9003"
diff --git a/docker-compose.yml b/docker-compose.yml
index 7ad3f87..30be36c 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -1,6 +1,8 @@
 services:
   graph:
-    build: .
+    build:
+      context: .
+      target: final
     container_name: git-contribution-graph
     restart: unless-stopped
     ports:
diff --git a/docker/php/xdebug.ini b/docker/php/xdebug.ini
new file mode 100644
index 0000000..97d92b7
--- /dev/null
+++ b/docker/php/xdebug.ini
@@ -0,0 +1,8 @@
+[xdebug]
+; Mode is controlled by the XDEBUG_MODE env var in docker-compose.override.yml.
+; Set XDEBUG_MODE=off in your shell to skip Xdebug for faster test runs.
+xdebug.mode=off
+xdebug.client_port=9003
+xdebug.client_host=host.docker.internal
+xdebug.start_with_request=yes
+xdebug.log=/tmp/xdebug.log
diff --git a/src/Controller/GraphController.php b/src/Controller/GraphController.php
index abbbac5..6fa2ebe 100644
--- a/src/Controller/GraphController.php
+++ b/src/Controller/GraphController.php
@@ -2,12 +2,11 @@
 
 namespace App\Controller;
 
-use App\Service\GiteaProvider;
-use App\Service\GitHubProvider;
-use App\Service\GitLabProvider;
+use App\Service\ProviderInterface;
 use App\Service\SvgRenderer;
 use Psr\Log\LoggerInterface;
 use Symfony\Component\DependencyInjection\Attribute\Autowire;
+use Symfony\Component\DependencyInjection\Attribute\TaggedIterator;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\Routing\Attribute\Route;
@@ -20,30 +19,13 @@ class GraphController
     private readonly array $allowedHosts;
 
     public function __construct(
-        private readonly GitHubProvider $github,
-        private readonly GitLabProvider $gitlab,
-        private readonly GiteaProvider $gitea,
+        #[TaggedIterator('app.provider')]
+        private readonly iterable $providers,
         private readonly SvgRenderer $renderer,
         private readonly CacheInterface $cache,
         private readonly LoggerInterface $logger,
         #[Autowire(env: 'ALLOWED_HOSTS')]
         string $allowedHosts = '',
-        #[Autowire(env: 'GITHUB_USER')]
-        private readonly string $githubUser = '',
-        #[Autowire(env: 'GITHUB_TOKEN')]
-        private readonly string $githubToken = '',
-        #[Autowire(env: 'GITLAB_USER')]
-        private readonly string $gitlabUser = '',
-        #[Autowire(env: 'GITLAB_TOKEN')]
-        private readonly string $gitlabToken = '',
-        #[Autowire(env: 'GITLAB_URL')]
-        private readonly string $gitlabUrl = '',
-        #[Autowire(env: 'GITEA_USER')]
-        private readonly string $giteaUser = '',
-        #[Autowire(env: 'GITEA_TOKEN')]
-        private readonly string $giteaToken = '',
-        #[Autowire(env: 'GITEA_URL')]
-        private readonly string $giteaUrl = '',
     ) {
         $this->allowedHosts = array_values(array_filter(array_map('trim', explode(',', $allowedHosts))));
     }
@@ -59,16 +41,13 @@ class GraphController
             return new Response('Forbidden', 403);
         }
 
-        $theme = $request->query->get('theme', 'dark');
-
+        $theme    = $request->query->get('theme', 'dark');
         $cacheKey = 'graph_' . $theme;
 
         $svg = $this->cache->get($cacheKey, function (ItemInterface $item) use ($theme): string {
             $item->expiresAfter(3600);
 
-            $contributions = $this->fetchAllContributions();
-
-            return $this->renderer->render($contributions, $theme);
+            return $this->renderer->render($this->fetchAllContributions(), $theme);
         });
 
         return new Response($svg, 200, [
@@ -83,51 +62,34 @@ class GraphController
         return new Response('{"status":"ok"}', 200, ['Content-Type' => 'application/json']);
     }
 
+    /** @return array<string, int> */
     private function fetchAllContributions(): array
     {
         $contributions = [];
 
-        if ($this->githubUser !== '' && $this->githubToken !== '') {
-            try {
-                $contributions = $this->merge($contributions, $this->github->fetch($this->githubUser, $this->githubToken));
-            } catch (\Throwable $e) {
-                $this->logger->warning('GitHub fetch failed: ' . $e->getMessage());
+        /** @var ProviderInterface $provider */
+        foreach ($this->providers as $provider) {
+            if (!$provider->isConfigured()) {
+                continue;
             }
-        }
 
-        if ($this->gitlabUser !== '' && $this->gitlabToken !== '') {
             try {
-                $contributions = $this->merge($contributions, $this->gitlab->fetch(
-                    $this->gitlabUser,
-                    $this->gitlabToken,
-                    $this->gitlabUrl !== '' ? $this->gitlabUrl : 'https://gitlab.com'
-                ));
+                $contributions = $this->merge($contributions, $provider->fetch());
             } catch (\Throwable $e) {
-                $this->logger->warning('GitLab fetch failed: ' . $e->getMessage());
-            }
-        }
-
-        if ($this->giteaUser !== '' && $this->giteaToken !== '' && $this->giteaUrl !== '') {
-            try {
-                $contributions = $this->merge($contributions, $this->gitea->fetch(
-                    $this->giteaUser,
-                    $this->giteaToken,
-                    rtrim($this->giteaUrl, '/')
-                ));
-            } catch (\Throwable $e) {
-                $this->logger->warning('Gitea fetch failed: ' . $e->getMessage());
+                $this->logger->warning(sprintf('%s fetch failed: %s', $provider::class, $e->getMessage()));
             }
         }
 
         return $contributions;
     }
 
-    /** Sum contributions by date from two maps. */
+    /** @param array<string, int> $base @param array<string, int> $new @return array<string, int> */
     private function merge(array $base, array $new): array
     {
         foreach ($new as $date => $count) {
             $base[$date] = ($base[$date] ?? 0) + $count;
         }
+
         return $base;
     }
 }
diff --git a/src/Service/GitHubProvider.php b/src/Service/GitHubProvider.php
index a206618..9c4a8f5 100644
--- a/src/Service/GitHubProvider.php
+++ b/src/Service/GitHubProvider.php
@@ -11,19 +11,26 @@ use Symfony\Contracts\HttpClient\HttpClientInterface;
  *
  * Required token scopes: read:user
  */
-class GitHubProvider
+class GitHubProvider implements ProviderInterface
 {
     private const GRAPHQL_URL = 'https://api.github.com/graphql';
 
     public function __construct(
         private readonly HttpClientInterface $client,
         private readonly GraphQLApiClientRegistryInterface $registry,
+        private readonly string $username,
+        private readonly string $token,
     ) {}
 
+    public function isConfigured(): bool
+    {
+        return $this->username !== '' && $this->token !== '';
+    }
+
     /**
      * @return array<string, int>  date (Y-m-d) => contribution count
      */
-    public function fetch(string $username, string $token): array
+    public function fetch(): array
     {
         $from = (new \DateTimeImmutable('-365 days'))->format('Y-m-d\T00:00:00\Z');
         $to   = (new \DateTimeImmutable())->format('Y-m-d\T23:59:59\Z');
@@ -32,7 +39,7 @@ class GitHubProvider
         $graphqlClient = $this->registry->get('github');
 
         $query = $graphqlClient->buildQuery(
-            ['user' => ['login' => $username]],
+            ['user' => ['login' => $this->username]],
             [
                 'contributionsCollection' => [
                     '_parameters' => ['from' => $from, 'to' => $to],
@@ -49,7 +56,7 @@ class GitHubProvider
         // transport sends form_params, so we use Symfony HttpClient here instead.
         $response = $this->client->request('POST', self::GRAPHQL_URL, [
             'headers' => [
-                'Authorization' => "Bearer $token",
+                'Authorization' => "Bearer {$this->token}",
                 'Content-Type'  => 'application/json',
             ],
             'json' => ['query' => $query],
diff --git a/src/Service/GitLabProvider.php b/src/Service/GitLabProvider.php
index 62159d6..2b5e6b6 100644
--- a/src/Service/GitLabProvider.php
+++ b/src/Service/GitLabProvider.php
@@ -10,26 +10,36 @@ use Symfony\Contracts\HttpClient\HttpClientInterface;
  * Required token scopes: read_user, read_api
  * Works with both gitlab.com and self-hosted instances.
  */
-class GitLabProvider
+class GitLabProvider implements ProviderInterface
 {
-    public function __construct(private readonly HttpClientInterface $client) {}
+    public function __construct(
+        private readonly HttpClientInterface $client,
+        private readonly string $username,
+        private readonly string $token,
+        private readonly string $baseUrl = '',
+    ) {}
+
+    public function isConfigured(): bool
+    {
+        return $this->username !== '' && $this->token !== '';
+    }
 
     /**
      * @return array<string, int>  date (Y-m-d) => event count
      */
-    public function fetch(string $username, string $token, string $baseUrl = 'https://gitlab.com'): array
+    public function fetch(): array
     {
-        $baseUrl = rtrim($baseUrl, '/');
+        $baseUrl = rtrim($this->baseUrl !== '' ? $this->baseUrl : 'https://gitlab.com', '/');
 
         // Resolve numeric user ID from username
         $userResponse = $this->client->request('GET', "$baseUrl/api/v4/users", [
-            'headers' => ['PRIVATE-TOKEN' => $token],
-            'query'   => ['username' => $username],
+            'headers' => ['PRIVATE-TOKEN' => $this->token],
+            'query'   => ['username' => $this->username],
         ]);
 
         $users = $userResponse->toArray();
         if (empty($users)) {
-            throw new \RuntimeException("GitLab: user '$username' not found on $baseUrl");
+            throw new \RuntimeException("GitLab: user '{$this->username}' not found on $baseUrl");
         }
         $userId = $users[0]['id'];
 
@@ -39,7 +49,7 @@ class GitLabProvider
 
         do {
             $response = $this->client->request('GET', "$baseUrl/api/v4/users/$userId/events", [
-                'headers' => ['PRIVATE-TOKEN' => $token],
+                'headers' => ['PRIVATE-TOKEN' => $this->token],
                 'query'   => [
                     'after'    => $after,
                     'per_page' => 100,
diff --git a/src/Service/GiteaProvider.php b/src/Service/GiteaProvider.php
index e5ba7bb..118c5d7 100644
--- a/src/Service/GiteaProvider.php
+++ b/src/Service/GiteaProvider.php
@@ -12,18 +12,28 @@ use Symfony\Contracts\HttpClient\HttpClientInterface;
  *
  * Required token scopes: read:user
  */
-class GiteaProvider
+class GiteaProvider implements ProviderInterface
 {
-    public function __construct(private readonly HttpClientInterface $client) {}
+    public function __construct(
+        private readonly HttpClientInterface $client,
+        private readonly string $username,
+        private readonly string $token,
+        private readonly string $baseUrl,
+    ) {}
+
+    public function isConfigured(): bool
+    {
+        return $this->username !== '' && $this->token !== '' && $this->baseUrl !== '';
+    }
 
     /**
      * @return array<string, int>  date (Y-m-d) => contribution count
      */
-    public function fetch(string $username, string $token, string $baseUrl): array
+    public function fetch(): array
     {
-        $baseUrl  = rtrim($baseUrl, '/');
-        $response = $this->client->request('GET', "$baseUrl/api/v1/users/$username/heatmap", [
-            'headers' => ['Authorization' => "token $token"],
+        $baseUrl  = rtrim($this->baseUrl, '/');
+        $response = $this->client->request('GET', "$baseUrl/api/v1/users/{$this->username}/heatmap", [
+            'headers' => ['Authorization' => "token {$this->token}"],
         ]);
 
         $data   = $response->toArray();
diff --git a/src/Service/ProviderInterface.php b/src/Service/ProviderInterface.php
new file mode 100644
index 0000000..d58119b
--- /dev/null
+++ b/src/Service/ProviderInterface.php
@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Service;
+
+interface ProviderInterface
+{
+    /** @return array<string, int>  date (Y-m-d) => contribution count */
+    public function fetch(): array;
+
+    public function isConfigured(): bool;
+}