diff --git a/.forgejo/workflows/android-emulator-tests.yml b/.forgejo/workflows/android-emulator-tests.yml
index 29a356e..6804514 100644
--- a/.forgejo/workflows/android-emulator-tests.yml
+++ b/.forgejo/workflows/android-emulator-tests.yml
@@ -17,15 +17,6 @@ jobs:
         with:
           fetch-depth: 50
 
-      - uses: cachix/install-nix-action@v27
-        with:
-          nix_path: nixpkgs=channel:nixos-25.11
-
-      - name: Enable Nix flakes
-        run: |
-          mkdir -p ~/.config/nix
-          echo "experimental-features = nix-command flakes" >> ~/.config/nix/nix.conf
-
       - name: Install Android SDK
         run: |
           SDK="${ANDROID_HOME:-$HOME/Android/Sdk}"
@@ -40,4 +31,4 @@ jobs:
           fi
 
       - name: Run Android Integration Tests
-        run: nix develop --no-warn-dirty --command task integration-android
+        run: task integration-android
diff --git a/.forgejo/workflows/ci.yml b/.forgejo/workflows/ci.yml
index 92bd77b..80d2dc6 100644
--- a/.forgejo/workflows/ci.yml
+++ b/.forgejo/workflows/ci.yml
@@ -16,14 +16,11 @@ jobs:
         with:
           fetch-depth: 50
 
-      - uses: cachix/install-nix-action@v27
-        with:
-          nix_path: nixpkgs=channel:nixos-25.11
-
-      - name: Enable Nix flakes
+      - name: Install Dagger & Task
         run: |
-          mkdir -p ~/.config/nix
-          echo "experimental-features = nix-command flakes" >> ~/.config/nix/nix.conf
+          curl -L https://dl.dagger.io/dagger/install.sh | BIN_DIR=/usr/local/bin sh
+          curl -sL https://taskfile.dev/install.sh | sh -s -- -b /usr/local/bin
+          sudo apt-get update && sudo apt-get install -y stunnel4 netcat-openbsd
 
       - name: Setup Dagger Remote Engine (via stunnel)
         env:
@@ -32,19 +29,10 @@ jobs:
           DAGGER_CA_CERT: ${{ secrets.DAGGER_CA_CERT }}
           DAGGER_CLIENT_CERT: ${{ secrets.DAGGER_CLIENT_CERT }}
           DAGGER_CLIENT_KEY: ${{ secrets.DAGGER_CLIENT_KEY }}
-        run: nix develop --no-warn-dirty --command scripts/setup_dagger_remote.sh
-
-      - name: Setup Dagger Remote Engine (via stunnel)
-        env:
-          DAGGER_STUNNEL_URL1: ${{ secrets.DAGGER_STUNNEL_URL1 }}
-          DAGGER_STUNNEL_URL2: ${{ secrets.DAGGER_STUNNEL_URL2 }}
-          DAGGER_CA_CERT: ${{ secrets.DAGGER_CA_CERT }}
-          DAGGER_CLIENT_CERT: ${{ secrets.DAGGER_CLIENT_CERT }}
-          DAGGER_CLIENT_KEY: ${{ secrets.DAGGER_CLIENT_KEY }}
-        run: nix develop --no-warn-dirty --command scripts/setup_dagger_remote.sh
+        run: scripts/setup_dagger_remote.sh
 
       - name: Run Full Check Suite
-        run: nix develop --no-warn-dirty --command dagger call --progress=plain -m ci check --source .
+        run: dagger call --progress=plain -m ci check --source .
 
   build-linux:
     name: Build Linux Release
@@ -57,14 +45,11 @@ jobs:
         with:
           fetch-depth: 50
 
-      - uses: cachix/install-nix-action@v27
-        with:
-          nix_path: nixpkgs=channel:nixos-25.11
-
-      - name: Enable Nix flakes
+      - name: Install Dagger & Task
         run: |
-          mkdir -p ~/.config/nix
-          echo "experimental-features = nix-command flakes" >> ~/.config/nix/nix.conf
+          curl -L https://dl.dagger.io/dagger/install.sh | BIN_DIR=/usr/local/bin sh
+          curl -sL https://taskfile.dev/install.sh | sh -s -- -b /usr/local/bin
+          sudo apt-get update && sudo apt-get install -y stunnel4 netcat-openbsd
 
       - name: Setup Dagger Remote Engine (via stunnel)
         env:
@@ -73,7 +58,7 @@ jobs:
           DAGGER_CA_CERT: ${{ secrets.DAGGER_CA_CERT }}
           DAGGER_CLIENT_CERT: ${{ secrets.DAGGER_CLIENT_CERT }}
           DAGGER_CLIENT_KEY: ${{ secrets.DAGGER_CLIENT_KEY }}
-        run: nix develop --no-warn-dirty --command scripts/setup_dagger_remote.sh
+        run: scripts/setup_dagger_remote.sh
 
       - name: Build & Deploy Linux to server
         continue-on-error: true
@@ -83,7 +68,7 @@ jobs:
           SSH_HOST: ${{ secrets.SSH_HOST }}
         run: |
           HASH=$(git rev-parse --short HEAD)
-          nix develop --no-warn-dirty --command dagger call --progress=plain -m ci deploy-linux --source . --ssh-key env:SSH_PRIVATE_KEY --ssh-user "$SSH_USER" --ssh-host "$SSH_HOST" --commit-hash "$HASH"
+          dagger call --progress=plain -m ci deploy-linux --source . --ssh-key env:SSH_PRIVATE_KEY --ssh-user "$SSH_USER" --ssh-host "$SSH_HOST" --commit-hash "$HASH"
 
   deploy-playstore:
     name: Build & Deploy to Play Store
@@ -96,14 +81,11 @@ jobs:
         with:
           fetch-depth: 50
 
-      - uses: cachix/install-nix-action@v27
-        with:
-          nix_path: nixpkgs=channel:nixos-25.11
-
-      - name: Enable Nix flakes
+      - name: Install Dagger & Task
         run: |
-          mkdir -p ~/.config/nix
-          echo "experimental-features = nix-command flakes" >> ~/.config/nix/nix.conf
+          curl -L https://dl.dagger.io/dagger/install.sh | BIN_DIR=/usr/local/bin sh
+          curl -sL https://taskfile.dev/install.sh | sh -s -- -b /usr/local/bin
+          sudo apt-get update && sudo apt-get install -y stunnel4 netcat-openbsd
 
       - name: Setup Dagger Remote Engine (via stunnel)
         env:
@@ -112,40 +94,14 @@ jobs:
           DAGGER_CA_CERT: ${{ secrets.DAGGER_CA_CERT }}
           DAGGER_CLIENT_CERT: ${{ secrets.DAGGER_CLIENT_CERT }}
           DAGGER_CLIENT_KEY: ${{ secrets.DAGGER_CLIENT_KEY }}
-        run: nix develop --no-warn-dirty --command scripts/setup_dagger_remote.sh
-
-      - name: Install Android SDK (cached on runner between runs)
-        run: |
-          SDK="${ANDROID_HOME:-$HOME/Android/Sdk}"
-          if [ ! -d "$SDK/platforms/android-34" ]; then
-            echo "Android SDK not found, installing..."
-            wget -q https://dl.google.com/android/repository/commandlinetools-linux-11076708_latest.zip -O /tmp/cmdtools.zip
-            mkdir -p "$SDK/cmdline-tools"
-            unzip -q /tmp/cmdtools.zip -d "$SDK/cmdline-tools"
-            [ -d "$SDK/cmdline-tools/cmdline-tools" ] && mv "$SDK/cmdline-tools/cmdline-tools" "$SDK/cmdline-tools/latest"
-            yes | "$SDK/cmdline-tools/latest/bin/sdkmanager" --licenses >/dev/null 2>&1 || true
-            "$SDK/cmdline-tools/latest/bin/sdkmanager" "platform-tools" "build-tools;34.0.0" "platforms;android-34"
-          else
-            echo "Android SDK cached, skipping install."
-          fi
-
-      - name: Prepare Keystore
-        env:
-          ANDROID_KEYSTORE_BASE64: ${{ secrets.ANDROID_KEYSTORE_BASE64 }}
-        run: |
-          if [ -n "$ANDROID_KEYSTORE_BASE64" ]; then
-            echo "$ANDROID_KEYSTORE_BASE64" | base64 -d > android/app/upload-keystore.jks
-          else
-            echo "Error: ANDROID_KEYSTORE_BASE64 secret is not set."
-            exit 1
-          fi
+        run: scripts/setup_dagger_remote.sh
 
       - name: Build & Deploy to Play Store
         env:
           ANDROID_KEYSTORE_PASSWORD: ${{ secrets.ANDROID_KEYSTORE_PASSWORD }}
           PLAY_STORE_CONFIG_JSON: ${{ secrets.PLAY_STORE_CONFIG_JSON }}
         run: |
-          nix develop --no-warn-dirty --command dagger call --progress=plain -m ci publish-android --source . --play-store-config env:PLAY_STORE_CONFIG_JSON
+          dagger call --progress=plain -m ci publish-android --source . --play-store-config env:PLAY_STORE_CONFIG_JSON
 
       - name: Build & Deploy APK to server
         continue-on-error: true
@@ -156,7 +112,7 @@ jobs:
           ANDROID_KEYSTORE_PASSWORD: ${{ secrets.ANDROID_KEYSTORE_PASSWORD }}
         run: |
           HASH=$(git rev-parse --short HEAD)
-          nix develop --no-warn-dirty --command dagger call --progress=plain -m ci deploy-apk --source . --ssh-key env:SSH_PRIVATE_KEY --ssh-user "$SSH_USER" --ssh-host "$SSH_HOST" --commit-hash "$HASH"
+          dagger call --progress=plain -m ci deploy-apk --source . --ssh-key env:SSH_PRIVATE_KEY --ssh-user "$SSH_USER" --ssh-host "$SSH_HOST" --commit-hash "$HASH"
 
   publish-website:
     name: Publish Website Build History
@@ -172,14 +128,11 @@ jobs:
         with:
           fetch-depth: 1
 
-      - uses: cachix/install-nix-action@v27
-        with:
-          nix_path: nixpkgs=channel:nixos-25.11
-
-      - name: Enable Nix flakes
+      - name: Install Dagger & Task
         run: |
-          mkdir -p ~/.config/nix
-          echo "experimental-features = nix-command flakes" >> ~/.config/nix/nix.conf
+          curl -L https://dl.dagger.io/dagger/install.sh | BIN_DIR=/usr/local/bin sh
+          curl -sL https://taskfile.dev/install.sh | sh -s -- -b /usr/local/bin
+          sudo apt-get update && sudo apt-get install -y stunnel4 netcat-openbsd
 
       - name: Setup Dagger Remote Engine (via stunnel)
         env:
@@ -188,7 +141,7 @@ jobs:
           DAGGER_CA_CERT: ${{ secrets.DAGGER_CA_CERT }}
           DAGGER_CLIENT_CERT: ${{ secrets.DAGGER_CLIENT_CERT }}
           DAGGER_CLIENT_KEY: ${{ secrets.DAGGER_CLIENT_KEY }}
-        run: nix develop --no-warn-dirty --command scripts/setup_dagger_remote.sh
+        run: scripts/setup_dagger_remote.sh
 
       - name: Generate build history and deploy website
         continue-on-error: true
@@ -197,4 +150,4 @@ jobs:
           SSH_USER: ${{ secrets.SSH_USER }}
           SSH_HOST: ${{ secrets.SSH_HOST }}
         run: |
-          nix develop --no-warn-dirty --command dagger call --progress=plain -m ci publish-website --source . --ssh-key env:SSH_PRIVATE_KEY --ssh-user "$SSH_USER" --ssh-host "$SSH_HOST"
+          dagger call --progress=plain -m ci publish-website --source . --ssh-key env:SSH_PRIVATE_KEY --ssh-user "$SSH_USER" --ssh-host "$SSH_HOST"
diff --git a/.forgejo/workflows/website.yml b/.forgejo/workflows/website.yml
index 09d6e6a..8c8150d 100644
--- a/.forgejo/workflows/website.yml
+++ b/.forgejo/workflows/website.yml
@@ -19,14 +19,11 @@ jobs:
         with:
           submodules: recursive
 
-      - uses: cachix/install-nix-action@v27
-        with:
-          nix_path: nixpkgs=channel:nixos-25.11
-
-      - name: Enable Nix flakes
+      - name: Install Dagger & Task
         run: |
-          mkdir -p ~/.config/nix
-          echo "experimental-features = nix-command flakes" >> ~/.config/nix/nix.conf
+          curl -L https://dl.dagger.io/dagger/install.sh | BIN_DIR=/usr/local/bin sh
+          curl -sL https://taskfile.dev/install.sh | sh -s -- -b /usr/local/bin
+          sudo apt-get update && sudo apt-get install -y stunnel4 netcat-openbsd
 
       - name: Setup Dagger Remote Engine (via stunnel)
         env:
@@ -35,7 +32,7 @@ jobs:
           DAGGER_CA_CERT: ${{ secrets.DAGGER_CA_CERT }}
           DAGGER_CLIENT_CERT: ${{ secrets.DAGGER_CLIENT_CERT }}
           DAGGER_CLIENT_KEY: ${{ secrets.DAGGER_CLIENT_KEY }}
-        run: nix develop --no-warn-dirty --command scripts/setup_dagger_remote.sh
+        run: scripts/setup_dagger_remote.sh
 
       - name: Build & Deploy Website
         env:
@@ -43,9 +40,9 @@ jobs:
           SSH_USER: ${{ secrets.WEBSITE_SSH_USER }}
           SSH_HOST: ${{ secrets.WEBSITE_SSH_HOST }}
         run: |
-          nix develop --no-warn-dirty --command dagger call --progress=plain -m ci publish-website --source . --ssh-key env:SSH_PRIVATE_KEY --ssh-user "$SSH_USER" --ssh-host "$SSH_HOST"
+          dagger call --progress=plain -m ci publish-website --source . --ssh-key env:SSH_PRIVATE_KEY --ssh-user "$SSH_USER" --ssh-host "$SSH_HOST"
 
       - name: Verify Website
         env:
           SSH_HOST: ${{ secrets.WEBSITE_SSH_HOST }}
-        run: nix develop --no-warn-dirty --command scripts/website-verify.sh
+        run: scripts/website-verify.sh
diff --git a/ci/main.go b/ci/main.go
index 53b6eec..a44be14 100644
--- a/ci/main.go
+++ b/ci/main.go
@@ -36,10 +36,6 @@ func (m *Ci) Base(source *dagger.Directory) *dagger.Container {
 			"clang", "cmake", "ninja-build", "pkg-config",
 			"libgtk-3-dev", "liblzma-dev", "libsecret-1-dev",
 			"libgcrypt20-dev", "libjsoncpp-dev", "sqlite3", "curl", "python3", "iproute2"}).
-		WithExec([]string{"curl", "-sL", "https://github.com/stalwartlabs/mail-server/releases/download/v0.14.1/stalwart-x86_64-unknown-linux-gnu.tar.gz", "-o", "/tmp/stalwart.tar.gz"}).
-		WithExec([]string{"tar", "-xzf", "/tmp/stalwart.tar.gz", "-C", "/usr/local/bin", "stalwart"}).
-		WithExec([]string{"chmod", "+x", "/usr/local/bin/stalwart"}).
-		WithExec([]string{"rm", "/tmp/stalwart.tar.gz"}).
 		WithMountedCache("/root/.pub-cache", dag.CacheVolume("flutter-pub-cache")).
 		WithMountedCache("/root/.gradle", dag.CacheVolume("gradle-cache")).
 		WithEnvVariable("PUB_CACHE", "/root/.pub-cache").
@@ -66,6 +62,23 @@ func (m *Ci) Deployer(sshKey *dagger.Secret) *dagger.Container {
 		WithEnvVariable("RSYNC_RSH", "ssh -o StrictHostKeyChecking=no -i /root/.ssh/id_ed25519")
 }
 
+// Latest Stalwart Mail Server as a Dagger Service
+func (m *Ci) Stalwart(source *dagger.Directory) *dagger.Service {
+	config := source.Directory("stalwart-dev").File("config.toml")
+
+	return dag.Container().
+		From("stalwartlabs/stalwart:latest").
+		WithFile("/etc/stalwart/config.toml", config).
+		// Create data dir in /tmp where permissions are usually more relaxed.
+		// Note: The Stalwart image might run as a non-root user.
+		WithExec([]string{"/bin/sh", "-c", "mkdir -p /tmp/stalwart && chmod 777 /tmp/stalwart"}).
+		WithExposedPort(8080). // JMAP
+		WithExposedPort(1430). // IMAP
+		WithExposedPort(1025). // SMTP
+		WithExposedPort(4190). // ManageSieve
+		AsService()
+}
+
 // Setup environment: pub get and build_runner
 func (m *Ci) Setup(source *dagger.Directory) *dagger.Container {
 	return m.Base(source).
@@ -145,8 +158,25 @@ func (m *Ci) Check(ctx context.Context, source *dagger.Directory) (string, error
 		return coverage, err
 	}
 
-	// Run backend tests (requires Stalwart)
-	testBackend, err := setup.WithExec([]string{"stalwart-dev/test.sh"}).Stdout(ctx)
+	// Run backend tests (requires Stalwart Service)
+	stalwart := m.Stalwart(source)
+	testBackend, err := setup.
+		WithServiceBinding("stalwart", stalwart).
+		WithEnvVariable("STALWART_IMAP_HOST", "stalwart").
+		WithEnvVariable("STALWART_SMTP_HOST", "stalwart").
+		WithEnvVariable("STALWART_URL", "http://stalwart:8080").
+		WithEnvVariable("STALWART_IMAP_PORT", "1430").
+		WithEnvVariable("STALWART_SMTP_PORT", "1025").
+		WithEnvVariable("STALWART_SIEVE_PORT", "4190").
+		WithEnvVariable("STALWART_USER_B", "alice@example.com").
+		WithEnvVariable("STALWART_PASS_B", "secret").
+		// USER_C/PASS_C needed for multi-account tests
+		WithEnvVariable("STALWART_USER_C", "bob@example.com").
+		WithEnvVariable("STALWART_PASS_C", "secret").
+		// We can't use stalwart-dev/test.sh directly because it tries to START stalwart.
+		// We just run the tests against the bound service.
+		WithExec([]string{"flutter", "test", "test/backend"}).
+		Stdout(ctx)
 	if err != nil {
 		return testBackend, err
 	}
@@ -225,8 +255,8 @@ func (m *Ci) PublishWebsite(
 // Build and return the Linux bundle
 func (m *Ci) BuildLinux(source *dagger.Directory) *dagger.Directory {
 	return m.Setup(source).
-		WithExec([]string{"flutter", "build", "linux", "--debug"}).
-		Directory("build/linux/x64/debug/bundle")
+		WithExec([]string{"flutter", "build", "linux", "--release"}).
+		Directory("build/linux/x64/release/bundle")
 }
 
 // Build and return the Linux bundle (release)
diff --git a/stalwart-dev/config.toml b/stalwart-dev/config.toml
index c11a30b..82af49e 100644
--- a/stalwart-dev/config.toml
+++ b/stalwart-dev/config.toml
@@ -1,10 +1,5 @@
 # Minimal Stalwart Mail configuration for local development and integration tests.
 #
-# Do not start directly — use stalwart-dev/start, which substitutes $STALWART_PORT
-# and writes a per-clone config into /tmp/stalwart-dev-PORT/ before starting.
-#
-# Check:  curl http://localhost:$STALWART_PORT/.well-known/jmap
-#
 # HTTP only — localhost testing, no TLS.
 # Two test accounts (alice, bob) for multi-account sync tests.
 
@@ -13,27 +8,27 @@ hostname = "localhost"
 
 [[server.listener]]
 id       = "jmap"
-bind     = ["127.0.0.1:8080"]
+bind     = ["0.0.0.0:8080"]
 protocol = "http"
 
 [[server.listener]]
 id       = "imap"
-bind     = ["127.0.0.1:1430"]
+bind     = ["0.0.0.0:1430"]
 protocol = "imap"
 
 [[server.listener]]
 id       = "smtp"
-bind     = ["127.0.0.1:1025"]
+bind     = ["0.0.0.0:1025"]
 protocol = "smtp"
 
 [[server.listener]]
 id       = "managesieve"
-bind     = ["127.0.0.1:4190"]
+bind     = ["0.0.0.0:4190"]
 protocol = "managesieve"
 
 [store."db"]
 type = "sqlite"
-path = "/tmp/stalwart-dev/data.sqlite"
+path = "/tmp/stalwart/data.sqlite"
 
 [storage]
 data      = "db"