diff --git a/.gitea/workflows/ci.yml b/.gitea/workflows/ci.yml
new file mode 100644
index 0000000..d41166f
--- /dev/null
+++ b/.gitea/workflows/ci.yml
@@ -0,0 +1,60 @@
+name: CI
+
+on:
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  check:
+    name: Lint and Test
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Install Rust
+        uses: actions-rust-lang/setup-rust-toolchain@v1
+        with:
+          toolchain: stable
+          components: rustfmt, clippy
+          cache: false
+
+      - name: Check formatting
+        run: cargo fmt --check
+
+      - name: Clippy
+        run: cargo clippy --tests -- -D warnings
+
+      - name: Test
+        run: cargo test
+
+      - name: Build
+        run: cargo build --release
+
+  version-check:
+    name: Version Check
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Compare versions
+        shell: bash
+        run: |
+          NEW_VERSION=$(grep -m1 '^version =' Cargo.toml | cut -d '"' -f 2)
+
+          git fetch origin ${{ github.base_ref }}
+          OLD_VERSION=$(git show origin/${{ github.base_ref }}:Cargo.toml | grep -m1 '^version =' | cut -d '"' -f 2)
+
+          echo "Old version (main): $OLD_VERSION"
+          echo "New version (PR): $NEW_VERSION"
+
+          if [ "$NEW_VERSION" = "$OLD_VERSION" ]; then
+            echo "Error: Cargo.toml version has not been updated in this PR!"
+            exit 1
+          else
+            echo "Success: Version updated from $OLD_VERSION to $NEW_VERSION"
+          fi
diff --git a/.gitea/workflows/release.yml b/.gitea/workflows/release.yml
new file mode 100644
index 0000000..bacc583
--- /dev/null
+++ b/.gitea/workflows/release.yml
@@ -0,0 +1,109 @@
+name: Release
+
+on:
+  push:
+    branches:
+      - main
+    tags:
+      - 'v*'
+
+jobs:
+  build:
+    name: Build and Release
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Install Rust
+        uses: actions-rust-lang/setup-rust-toolchain@v1
+        with:
+          toolchain: stable
+          cache: false
+
+      - name: Install packaging tools
+        run: apt-get update && apt-get install -y dpkg-dev
+
+      - name: Get Version
+        id: get_version
+        run: |
+          VERSION=$(grep -m1 '^version =' Cargo.toml | cut -d '"' -f 2)
+          echo "VERSION=$VERSION" >> $GITHUB_OUTPUT
+          if [[ "${{ github.ref }}" == refs/tags/v* ]]; then
+            echo "TAG=${{ github.ref_name }}" >> $GITHUB_OUTPUT
+          else
+            echo "TAG=v$VERSION" >> $GITHUB_OUTPUT
+          fi
+
+      - name: Check if Release Exists
+        id: check_release
+        shell: bash
+        run: |
+          HTTP_STATUS=$(curl -s -o /dev/null -w "%{http_code}" \
+            -H "Authorization: token ${{ secrets.GITHUB_TOKEN }}" \
+            "${{ github.server_url }}/api/v1/repos/${{ github.repository }}/releases/tags/${{ steps.get_version.outputs.TAG }}")
+
+          if [ "$HTTP_STATUS" = "200" ]; then
+            echo "EXISTS=true" >> $GITHUB_OUTPUT
+            echo "Release already exists for tag ${{ steps.get_version.outputs.TAG }}. Skipping."
+          else
+            echo "EXISTS=false" >> $GITHUB_OUTPUT
+          fi
+
+      - name: Build
+        if: steps.check_release.outputs.EXISTS == 'false'
+        run: cargo build --release
+
+      - name: Test
+        if: steps.check_release.outputs.EXISTS == 'false'
+        run: cargo test
+
+      - name: Package .deb
+        if: steps.check_release.outputs.EXISTS == 'false'
+        env:
+          VERSION: ${{ steps.get_version.outputs.VERSION }}
+          TAG: ${{ steps.get_version.outputs.TAG }}
+        run: |
+          PKG="fluxo-rs_${VERSION}_amd64"
+
+          mkdir -p "${PKG}/DEBIAN"
+          mkdir -p "${PKG}/usr/bin"
+
+          cp target/release/fluxo-rs "${PKG}/usr/bin/"
+          strip "${PKG}/usr/bin/fluxo-rs"
+
+          printf '%s\n' \
+            "Package: fluxo-rs" \
+            "Version: ${VERSION}" \
+            "Section: utils" \
+            "Priority: optional" \
+            "Architecture: amd64" \
+            "Maintainer: fluxo-rs contributors" \
+            "Description: High-performance daemon/client for Waybar custom modules" \
+            " fluxo-rs is a compiled Rust daemon that polls system metrics and" \
+            " serves formatted JSON output to Waybar custom modules over a Unix" \
+            " domain socket. Replaces shell scripts with a single binary." \
+            > "${PKG}/DEBIAN/control"
+
+          dpkg-deb --build "${PKG}"
+
+          mv "${PKG}.deb" "fluxo-rs-${TAG}-amd64.deb"
+          echo "Built: fluxo-rs-${TAG}-amd64.deb"
+
+      - name: Create Release and Upload Assets
+        if: steps.check_release.outputs.EXISTS == 'false'
+        uses: https://github.com/softprops/action-gh-release@v1
+        with:
+          tag_name: ${{ steps.get_version.outputs.TAG }}
+          name: Release ${{ steps.get_version.outputs.TAG }}
+          body: |
+            Automated release for version ${{ steps.get_version.outputs.VERSION }}
+            Commit: ${{ github.sha }}
+            Branch: ${{ github.ref_name }}
+          files: |
+            fluxo-rs-${{ steps.get_version.outputs.TAG }}-amd64.deb
+            target/release/fluxo-rs
+          draft: false
+          prerelease: false
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
diff --git a/Cargo.lock b/Cargo.lock
index 2289025..1c8620b 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -169,6 +169,22 @@ version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "877a4ace8713b0bcf2a4e7eec82529c029f1d0619886d18145fea96c3ffe5c0f"
 
+[[package]]
+name = "errno"
+version = "0.3.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "39cab71617ae0d63f51a36d69f866391735b51691dbda63cf6f96d042b63efeb"
+dependencies = [
+ "libc",
+ "windows-sys",
+]
+
+[[package]]
+name = "fastrand"
+version = "2.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "37909eebbb50d72f9059c3b6d82c0463f2ff062c9e95845c43a6c9c0355411be"
+
 [[package]]
 name = "fluxo-rs"
 version = "0.2.0"
@@ -180,11 +196,40 @@ dependencies = [
  "serde",
  "serde_json",
  "sysinfo",
+ "tempfile",
  "toml",
  "tracing",
  "tracing-subscriber",
 ]
 
+[[package]]
+name = "foldhash"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d9c4f5dac5e15c24eb999c26181a6ca40b39fe946cbe4c263c7209467bc83af2"
+
+[[package]]
+name = "getrandom"
+version = "0.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0de51e6874e94e7bf76d726fc5d13ba782deca734ff60d5bb2fb2607c7406555"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "r-efi",
+ "wasip2",
+ "wasip3",
+]
+
+[[package]]
+name = "hashbrown"
+version = "0.15.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9229cfe53dfd69f0609a49f65461bd93001ea1ef889cd5529dd176593f5338a1"
+dependencies = [
+ "foldhash",
+]
+
 [[package]]
 name = "hashbrown"
 version = "0.16.1"
@@ -197,6 +242,12 @@ version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2304e00983f87ffb38b55b444b5e3b60a884b5d30c0fca7d82fe33449bbe55ea"
 
+[[package]]
+name = "id-arena"
+version = "2.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3d3067d79b975e8844ca9eb072e16b31c3c1c36928edf9c6789548c524d0d954"
+
 [[package]]
 name = "indexmap"
 version = "2.13.0"
@@ -204,7 +255,9 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7714e70437a7dc3ac8eb7e6f8df75fd8eb422675fc7678aff7364301092b1017"
 dependencies = [
  "equivalent",
- "hashbrown",
+ "hashbrown 0.16.1",
+ "serde",
+ "serde_core",
 ]
 
 [[package]]
@@ -225,12 +278,24 @@ version = "1.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
 
+[[package]]
+name = "leb128fmt"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "09edd9e8b54e49e587e4f6295a7d29c3ea94d469cb40ab8ca70b288248a81db2"
+
 [[package]]
 name = "libc"
 version = "0.2.183"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b5b646652bf6661599e1da8901b3b9522896f01e736bad5f723fe7a3a27f899d"
 
+[[package]]
+name = "linux-raw-sys"
+version = "0.12.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "32a66949e030da00e8c7d4434b251670a91556f4144941d37452769c25d58a53"
+
 [[package]]
 name = "log"
 version = "0.4.29"
@@ -334,6 +399,16 @@ version = "0.2.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a89322df9ebe1c1578d689c92318e070967d1042b512afbe49518723f4e6d5cd"
 
+[[package]]
+name = "prettyplease"
+version = "0.2.37"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "479ca8adacdd7ce8f1fb39ce9ecccbfe93a3f1344b3d0d97f20bc0196208f62b"
+dependencies = [
+ "proc-macro2",
+ "syn",
+]
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.106"
@@ -352,6 +427,12 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "r-efi"
+version = "6.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f8dcc9c7d52a811697d2151c701e0d08956f92b0e24136cf4cf27b57a6a0d9bf"
+
 [[package]]
 name = "regex"
 version = "1.12.3"
@@ -381,6 +462,25 @@ version = "0.8.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "dc897dd8d9e8bd1ed8cdad82b5966c3e0ecae09fb1907d58efaa013543185d0a"
 
+[[package]]
+name = "rustix"
+version = "1.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b6fe4565b9518b83ef4f91bb47ce29620ca828bd32cb7e408f0062e9930ba190"
+dependencies = [
+ "bitflags",
+ "errno",
+ "libc",
+ "linux-raw-sys",
+ "windows-sys",
+]
+
+[[package]]
+name = "semver"
+version = "1.0.27"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d767eb0aabc880b29956c35734170f26ed551a859dbd361d140cdbeca61ab1e2"
+
 [[package]]
 name = "serde"
 version = "1.0.228"
@@ -479,6 +579,19 @@ dependencies = [
  "windows",
 ]
 
+[[package]]
+name = "tempfile"
+version = "3.27.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "32497e9a4c7b38532efcdebeef879707aa9f794296a4f0244f6f69e9bc8574bd"
+dependencies = [
+ "fastrand",
+ "getrandom",
+ "once_cell",
+ "rustix",
+ "windows-sys",
+]
+
 [[package]]
 name = "thread_local"
 version = "1.1.9"
@@ -594,6 +707,12 @@ version = "1.0.24"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e6e4313cd5fcd3dad5cafa179702e2b244f760991f45397d14d4ebf38247da75"
 
+[[package]]
+name = "unicode-xid"
+version = "0.2.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ebc1c04c71510c7f702b52b7c350734c9ff1295c464a03335b00bb84fc54f853"
+
 [[package]]
 name = "utf8parse"
 version = "0.2.2"
@@ -606,6 +725,58 @@ version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ba73ea9cf16a25df0c8caa16c51acb937d5712a8429db78a3ee29d5dcacd3a65"
 
+[[package]]
+name = "wasip2"
+version = "1.0.2+wasi-0.2.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9517f9239f02c069db75e65f174b3da828fe5f5b945c4dd26bd25d89c03ebcf5"
+dependencies = [
+ "wit-bindgen",
+]
+
+[[package]]
+name = "wasip3"
+version = "0.4.0+wasi-0.3.0-rc-2026-01-06"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5428f8bf88ea5ddc08faddef2ac4a67e390b88186c703ce6dbd955e1c145aca5"
+dependencies = [
+ "wit-bindgen",
+]
+
+[[package]]
+name = "wasm-encoder"
+version = "0.244.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "990065f2fe63003fe337b932cfb5e3b80e0b4d0f5ff650e6985b1048f62c8319"
+dependencies = [
+ "leb128fmt",
+ "wasmparser",
+]
+
+[[package]]
+name = "wasm-metadata"
+version = "0.244.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bb0e353e6a2fbdc176932bbaab493762eb1255a7900fe0fea1a2f96c296cc909"
+dependencies = [
+ "anyhow",
+ "indexmap",
+ "wasm-encoder",
+ "wasmparser",
+]
+
+[[package]]
+name = "wasmparser"
+version = "0.244.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "47b807c72e1bac69382b3a6fb3dbe8ea4c0ed87ff5629b8685ae6b9a611028fe"
+dependencies = [
+ "bitflags",
+ "hashbrown 0.15.5",
+ "indexmap",
+ "semver",
+]
+
 [[package]]
 name = "winapi"
 version = "0.3.9"
@@ -753,6 +924,94 @@ version = "0.7.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "df79d97927682d2fd8adb29682d1140b343be4ac0f08fd68b7765d9c059d3945"
 
+[[package]]
+name = "wit-bindgen"
+version = "0.51.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d7249219f66ced02969388cf2bb044a09756a083d0fab1e566056b04d9fbcaa5"
+dependencies = [
+ "wit-bindgen-rust-macro",
+]
+
+[[package]]
+name = "wit-bindgen-core"
+version = "0.51.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ea61de684c3ea68cb082b7a88508a8b27fcc8b797d738bfc99a82facf1d752dc"
+dependencies = [
+ "anyhow",
+ "heck",
+ "wit-parser",
+]
+
+[[package]]
+name = "wit-bindgen-rust"
+version = "0.51.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b7c566e0f4b284dd6561c786d9cb0142da491f46a9fbed79ea69cdad5db17f21"
+dependencies = [
+ "anyhow",
+ "heck",
+ "indexmap",
+ "prettyplease",
+ "syn",
+ "wasm-metadata",
+ "wit-bindgen-core",
+ "wit-component",
+]
+
+[[package]]
+name = "wit-bindgen-rust-macro"
+version = "0.51.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0c0f9bfd77e6a48eccf51359e3ae77140a7f50b1e2ebfe62422d8afdaffab17a"
+dependencies = [
+ "anyhow",
+ "prettyplease",
+ "proc-macro2",
+ "quote",
+ "syn",
+ "wit-bindgen-core",
+ "wit-bindgen-rust",
+]
+
+[[package]]
+name = "wit-component"
+version = "0.244.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9d66ea20e9553b30172b5e831994e35fbde2d165325bec84fc43dbf6f4eb9cb2"
+dependencies = [
+ "anyhow",
+ "bitflags",
+ "indexmap",
+ "log",
+ "serde",
+ "serde_derive",
+ "serde_json",
+ "wasm-encoder",
+ "wasm-metadata",
+ "wasmparser",
+ "wit-parser",
+]
+
+[[package]]
+name = "wit-parser"
+version = "0.244.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ecc8ac4bc1dc3381b7f59c34f00b67e18f910c2c0f50015669dde7def656a736"
+dependencies = [
+ "anyhow",
+ "id-arena",
+ "indexmap",
+ "log",
+ "semver",
+ "serde",
+ "serde_derive",
+ "serde_json",
+ "unicode-xid",
+ "wasmparser",
+]
+
 [[package]]
 name = "zmij"
 version = "1.0.21"
diff --git a/Cargo.toml b/Cargo.toml
index ad5b0cf..dc6f275 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -14,3 +14,6 @@ sysinfo = "0.38.4"
 toml = "1.0.6"
 tracing = "0.1.44"
 tracing-subscriber = { version = "0.3.23", features = ["env-filter"] }
+
+[dev-dependencies]
+tempfile = "3"
diff --git a/src/config.rs b/src/config.rs
index cc148c7..638384b 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -1,6 +1,8 @@
+use regex::Regex;
 use serde::Deserialize;
 use std::fs;
 use std::path::PathBuf;
+use std::sync::LazyLock;
 use tracing::{debug, info, warn};
 
 #[derive(Deserialize, Default)]
@@ -224,6 +226,80 @@ impl Default for GameConfig {
     }
 }
 
+static TOKEN_RE: LazyLock<Regex> =
+    LazyLock::new(|| Regex::new(r"\{([a-zA-Z0-9_]+)(?::([<>\^])?(\d+)?(?:\.(\d+))?)?\}").unwrap());
+
+fn extract_tokens(format_str: &str) -> Vec<String> {
+    TOKEN_RE
+        .captures_iter(format_str)
+        .map(|cap| cap[1].to_string())
+        .collect()
+}
+
+fn validate_format(label: &str, format_str: &str, known_tokens: &[&str]) {
+    for token in extract_tokens(format_str) {
+        if !known_tokens.contains(&token.as_str()) {
+            warn!(
+                "Config [{}]: unknown token '{{{}}}' in format string. Known tokens: {:?}",
+                label, token, known_tokens
+            );
+        }
+    }
+}
+
+impl Config {
+    pub fn validate(&self) {
+        validate_format(
+            "network",
+            &self.network.format,
+            &["interface", "ip", "rx", "tx"],
+        );
+        validate_format("cpu", &self.cpu.format, &["usage", "temp"]);
+        validate_format("memory", &self.memory.format, &["used", "total"]);
+        validate_format(
+            "gpu.amd",
+            &self.gpu.format_amd,
+            &["usage", "vram_used", "vram_total", "temp"],
+        );
+        validate_format("gpu.intel", &self.gpu.format_intel, &["usage", "freq"]);
+        validate_format(
+            "gpu.nvidia",
+            &self.gpu.format_nvidia,
+            &["usage", "vram_used", "vram_total", "temp"],
+        );
+        validate_format(
+            "sys",
+            &self.sys.format,
+            &["uptime", "load1", "load5", "load15", "procs"],
+        );
+        validate_format("disk", &self.disk.format, &["mount", "used", "total"]);
+        validate_format("pool", &self.pool.format, &["used", "total"]);
+        validate_format("power", &self.power.format, &["percentage", "icon"]);
+        validate_format("buds", &self.buds.format, &["left", "right", "anc"]);
+        validate_format(
+            "audio.sink_unmuted",
+            &self.audio.format_sink_unmuted,
+            &["name", "icon", "volume"],
+        );
+        validate_format(
+            "audio.sink_muted",
+            &self.audio.format_sink_muted,
+            &["name", "icon"],
+        );
+        validate_format(
+            "audio.source_unmuted",
+            &self.audio.format_source_unmuted,
+            &["name", "icon", "volume"],
+        );
+        validate_format(
+            "audio.source_muted",
+            &self.audio.format_source_muted,
+            &["name", "icon"],
+        );
+        validate_format("bt.connected", &self.bt.format_connected, &["alias"]);
+    }
+}
+
 pub fn load_config(custom_path: Option<PathBuf>) -> Config {
     let config_path = custom_path.unwrap_or_else(|| {
         let config_dir = std::env::var("XDG_CONFIG_HOME")
@@ -236,9 +312,10 @@ pub fn load_config(custom_path: Option<PathBuf>) -> Config {
     });
 
     if let Ok(content) = fs::read_to_string(&config_path) {
-        match toml::from_str(&content) {
+        match toml::from_str::<Config>(&content) {
             Ok(cfg) => {
                 info!("Successfully loaded configuration from {:?}", config_path);
+                cfg.validate();
                 cfg
             }
             Err(e) => {
@@ -255,3 +332,72 @@ pub fn load_config(custom_path: Option<PathBuf>) -> Config {
         Config::default()
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::io::Write;
+
+    #[test]
+    fn test_default_config() {
+        let config = Config::default();
+        assert_eq!(
+            config.general.menu_command,
+            "fuzzel --dmenu --prompt '{prompt}'"
+        );
+        assert!(config.cpu.format.contains("usage"));
+        assert!(config.cpu.format.contains("temp"));
+        assert!(config.memory.format.contains("used"));
+        assert!(config.memory.format.contains("total"));
+    }
+
+    #[test]
+    fn test_load_missing_config() {
+        let config = load_config(Some(PathBuf::from("/nonexistent/config.toml")));
+        // Should fallback to defaults without panicking
+        assert_eq!(
+            config.general.menu_command,
+            "fuzzel --dmenu --prompt '{prompt}'"
+        );
+    }
+
+    #[test]
+    fn test_load_valid_partial_config() {
+        let mut tmpfile = tempfile::NamedTempFile::new().unwrap();
+        // In TOML, braces have no special meaning in strings
+        writeln!(tmpfile, "[cpu]").unwrap();
+        writeln!(tmpfile, "format = \"custom: {{usage}}\"").unwrap();
+
+        let config = load_config(Some(tmpfile.path().to_path_buf()));
+        // TOML treats {{ as literal {{ (no escape), so the value is "custom: {{usage}}"
+        assert!(config.cpu.format.contains("usage"));
+        // Other sections still have defaults
+        assert!(config.memory.format.contains("used"));
+    }
+
+    #[test]
+    fn test_load_invalid_toml() {
+        let mut tmpfile = tempfile::NamedTempFile::new().unwrap();
+        write!(tmpfile, "this is not valid toml {{{{").unwrap();
+
+        let config = load_config(Some(tmpfile.path().to_path_buf()));
+        // Should fallback to defaults
+        assert_eq!(
+            config.general.menu_command,
+            "fuzzel --dmenu --prompt '{prompt}'"
+        );
+    }
+
+    #[test]
+    fn test_load_empty_config() {
+        let tmpfile = tempfile::NamedTempFile::new().unwrap();
+        // Empty file is valid TOML, all sections default
+
+        let config = load_config(Some(tmpfile.path().to_path_buf()));
+        assert_eq!(
+            config.general.menu_command,
+            "fuzzel --dmenu --prompt '{prompt}'"
+        );
+        assert!(config.cpu.format.contains("usage"));
+    }
+}
diff --git a/src/modules/bt.rs b/src/modules/bt.rs
index cef505c..0e3ed19 100644
--- a/src/modules/bt.rs
+++ b/src/modules/bt.rs
@@ -27,14 +27,15 @@ impl WaybarModule for BtModule {
         }
 
         if let Ok(stdout) = run_command("bluetoothctl", &["show"])
-            && stdout.contains("Powered: no") {
-                return Ok(WaybarOutput {
-                    text: config.bt.format_disabled.clone(),
-                    tooltip: Some("Bluetooth Disabled".to_string()),
-                    class: Some("disabled".to_string()),
-                    percentage: None,
-                });
-            }
+            && stdout.contains("Powered: no")
+        {
+            return Ok(WaybarOutput {
+                text: config.bt.format_disabled.clone(),
+                tooltip: Some("Bluetooth Disabled".to_string()),
+                class: Some("disabled".to_string()),
+                percentage: None,
+            });
+        }
 
         if let Some(mac) = find_audio_device() {
             let info = run_command("bluetoothctl", &["info", &mac])?;
@@ -90,12 +91,13 @@ impl WaybarModule for BtModule {
 
 fn find_audio_device() -> Option<String> {
     if let Ok(sink) = run_command("pactl", &["get-default-sink"])
-        && sink.starts_with("bluez_output.") {
-            let parts: Vec<&str> = sink.split('.').collect();
-            if parts.len() >= 2 {
-                return Some(parts[1].replace('_', ":"));
-            }
+        && sink.starts_with("bluez_output.")
+    {
+        let parts: Vec<&str> = sink.split('.').collect();
+        if parts.len() >= 2 {
+            return Some(parts[1].replace('_', ":"));
         }
+    }
 
     if let Ok(stdout) = run_command("bluetoothctl", &["devices", "Connected"]) {
         for line in stdout.lines() {
@@ -104,9 +106,10 @@ fn find_audio_device() -> Option<String> {
                 if parts.len() >= 2 {
                     let mac = parts[1];
                     if let Ok(info_str) = run_command("bluetoothctl", &["info", mac])
-                        && info_str.contains("0000110b-0000-1000-8000-00805f9b34fb") {
-                            return Some(mac.to_string());
-                        }
+                        && info_str.contains("0000110b-0000-1000-8000-00805f9b34fb")
+                    {
+                        return Some(mac.to_string());
+                    }
                 }
             }
         }
diff --git a/src/modules/buds.rs b/src/modules/buds.rs
index 00dc1ac..d6cf38b 100644
--- a/src/modules/buds.rs
+++ b/src/modules/buds.rs
@@ -2,9 +2,8 @@ use crate::config::Config;
 use crate::modules::WaybarModule;
 use crate::output::WaybarOutput;
 use crate::state::SharedState;
-use crate::utils::{TokenValue, format_template};
+use crate::utils::{TokenValue, format_template, run_command};
 use anyhow::Result;
-use std::process::Command;
 
 pub struct BudsModule;
 
@@ -15,8 +14,7 @@ impl WaybarModule for BudsModule {
 
         match *action {
             "cycle_anc" => {
-                let output = Command::new("pbpctrl").args(["get", "anc"]).output()?;
-                let current_mode = String::from_utf8_lossy(&output.stdout).trim().to_string();
+                let current_mode = run_command("pbpctrl", &["get", "anc"])?;
 
                 let next_mode = match current_mode.as_str() {
                     "active" => "aware",
@@ -24,9 +22,7 @@ impl WaybarModule for BudsModule {
                     _ => "active",
                 };
 
-                Command::new("pbpctrl")
-                    .args(["set", "anc", next_mode])
-                    .status()?;
+                let _ = run_command("pbpctrl", &["set", "anc", next_mode]);
                 return Ok(WaybarOutput {
                     text: String::new(),
                     tooltip: None,
@@ -35,9 +31,7 @@ impl WaybarModule for BudsModule {
                 });
             }
             "connect" => {
-                Command::new("bluetoothctl")
-                    .args(["connect", mac])
-                    .status()?;
+                let _ = run_command("bluetoothctl", &["connect", mac]);
                 return Ok(WaybarOutput {
                     text: String::new(),
                     tooltip: None,
@@ -46,9 +40,7 @@ impl WaybarModule for BudsModule {
                 });
             }
             "disconnect" => {
-                Command::new("bluetoothctl")
-                    .args(["disconnect", mac])
-                    .status()?;
+                let _ = run_command("bluetoothctl", &["disconnect", mac]);
                 return Ok(WaybarOutput {
                     text: String::new(),
                     tooltip: None,
@@ -62,8 +54,7 @@ impl WaybarModule for BudsModule {
             }
         }
 
-        let bt_info = Command::new("bluetoothctl").args(["info", mac]).output()?;
-        let bt_str = String::from_utf8_lossy(&bt_info.stdout);
+        let bt_str = run_command("bluetoothctl", &["info", mac])?;
 
         if !bt_str.contains("Connected: yes") {
             return Ok(WaybarOutput {
@@ -74,18 +65,18 @@ impl WaybarModule for BudsModule {
             });
         }
 
-        let bat_cmd = Command::new("pbpctrl").args(["show", "battery"]).output();
-        if bat_cmd.is_err() || !bat_cmd.as_ref().unwrap().status.success() {
-            return Ok(WaybarOutput {
-                text: config.buds.format_disconnected.clone(),
-                tooltip: Some("Pixel Buds Pro 2 connected (No Data)".to_string()),
-                class: Some("disconnected".to_string()),
-                percentage: None,
-            });
-        }
+        let bat_output = match run_command("pbpctrl", &["show", "battery"]) {
+            Ok(output) => output,
+            Err(_) => {
+                return Ok(WaybarOutput {
+                    text: config.buds.format_disconnected.clone(),
+                    tooltip: Some("Pixel Buds Pro 2 connected (No Data)".to_string()),
+                    class: Some("disconnected".to_string()),
+                    percentage: None,
+                });
+            }
+        };
 
-        let bat_result = bat_cmd.unwrap();
-        let bat_output = String::from_utf8_lossy(&bat_result.stdout);
         let mut left_bud = "unknown";
         let mut right_bud = "unknown";
 
@@ -117,8 +108,7 @@ impl WaybarModule for BudsModule {
             format!("{}%", right_bud)
         };
 
-        let anc_cmd = Command::new("pbpctrl").args(["get", "anc"]).output()?;
-        let current_mode = String::from_utf8_lossy(&anc_cmd.stdout).trim().to_string();
+        let current_mode = run_command("pbpctrl", &["get", "anc"]).unwrap_or_default();
 
         let (anc_icon, class) = match current_mode.as_str() {
             "active" => ("ANC", "anc-active"),
diff --git a/src/modules/cpu.rs b/src/modules/cpu.rs
index 8c6e043..f266d67 100644
--- a/src/modules/cpu.rs
+++ b/src/modules/cpu.rs
@@ -45,3 +45,58 @@ impl WaybarModule for CpuModule {
         })
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::state::{AppState, CpuState, mock_state};
+
+    #[test]
+    fn test_cpu_normal() {
+        let state = mock_state(AppState {
+            cpu: CpuState {
+                usage: 25.0,
+                temp: 45.0,
+                model: "Test CPU".into(),
+            },
+            ..Default::default()
+        });
+        let config = Config::default();
+        let output = CpuModule.run(&config, &state, &[]).unwrap();
+        assert!(output.text.contains("25.0"));
+        assert!(output.text.contains("45.0"));
+        assert_eq!(output.class.as_deref(), Some("normal"));
+        assert_eq!(output.percentage, Some(25));
+        assert_eq!(output.tooltip.as_deref(), Some("Test CPU"));
+    }
+
+    #[test]
+    fn test_cpu_high() {
+        let state = mock_state(AppState {
+            cpu: CpuState {
+                usage: 80.0,
+                temp: 70.0,
+                model: "Test".into(),
+            },
+            ..Default::default()
+        });
+        let config = Config::default();
+        let output = CpuModule.run(&config, &state, &[]).unwrap();
+        assert_eq!(output.class.as_deref(), Some("high"));
+    }
+
+    #[test]
+    fn test_cpu_max() {
+        let state = mock_state(AppState {
+            cpu: CpuState {
+                usage: 99.0,
+                temp: 95.0,
+                model: "Test".into(),
+            },
+            ..Default::default()
+        });
+        let config = Config::default();
+        let output = CpuModule.run(&config, &state, &[]).unwrap();
+        assert_eq!(output.class.as_deref(), Some("max"));
+    }
+}
diff --git a/src/modules/disk.rs b/src/modules/disk.rs
index 2aacc4b..d333101 100644
--- a/src/modules/disk.rs
+++ b/src/modules/disk.rs
@@ -65,3 +65,48 @@ impl WaybarModule for DiskModule {
         Err(anyhow::anyhow!("Mountpoint {} not found", mountpoint))
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::state::{AppState, DiskInfo, mock_state};
+
+    fn state_with_disk(mount: &str, total: u64, available: u64) -> crate::state::SharedState {
+        mock_state(AppState {
+            disks: vec![DiskInfo {
+                mount_point: mount.to_string(),
+                filesystem: "ext4".to_string(),
+                total_bytes: total,
+                available_bytes: available,
+            }],
+            ..Default::default()
+        })
+    }
+
+    #[test]
+    fn test_disk_found() {
+        let gb = 1024 * 1024 * 1024;
+        let state = state_with_disk("/", 100 * gb, 60 * gb);
+        let config = Config::default();
+        let output = DiskModule.run(&config, &state, &["/"]).unwrap();
+        assert_eq!(output.class.as_deref(), Some("normal"));
+        assert_eq!(output.percentage, Some(40)); // 40% used
+    }
+
+    #[test]
+    fn test_disk_high() {
+        let gb = 1024 * 1024 * 1024;
+        let state = state_with_disk("/", 100 * gb, 15 * gb);
+        let config = Config::default();
+        let output = DiskModule.run(&config, &state, &["/"]).unwrap();
+        assert_eq!(output.class.as_deref(), Some("high")); // 85% used
+    }
+
+    #[test]
+    fn test_disk_not_found() {
+        let state = mock_state(AppState::default());
+        let config = Config::default();
+        let result = DiskModule.run(&config, &state, &["/nonexistent"]);
+        assert!(result.is_err());
+    }
+}
diff --git a/src/modules/memory.rs b/src/modules/memory.rs
index 885f421..946d708 100644
--- a/src/modules/memory.rs
+++ b/src/modules/memory.rs
@@ -47,3 +47,55 @@ impl WaybarModule for MemoryModule {
         })
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::state::{AppState, MemoryState, mock_state};
+
+    #[test]
+    fn test_memory_normal() {
+        let state = mock_state(AppState {
+            memory: MemoryState {
+                used_gb: 8.0,
+                total_gb: 32.0,
+            },
+            ..Default::default()
+        });
+        let config = Config::default();
+        let output = MemoryModule.run(&config, &state, &[]).unwrap();
+        assert!(output.text.contains("8.00"));
+        assert!(output.text.contains("32.00"));
+        assert_eq!(output.class.as_deref(), Some("normal"));
+        assert_eq!(output.percentage, Some(25)); // 8/32 = 25%
+    }
+
+    #[test]
+    fn test_memory_high() {
+        let state = mock_state(AppState {
+            memory: MemoryState {
+                used_gb: 26.0,
+                total_gb: 32.0,
+            },
+            ..Default::default()
+        });
+        let config = Config::default();
+        let output = MemoryModule.run(&config, &state, &[]).unwrap();
+        assert_eq!(output.class.as_deref(), Some("high")); // 81%
+    }
+
+    #[test]
+    fn test_memory_zero_total() {
+        let state = mock_state(AppState {
+            memory: MemoryState {
+                used_gb: 0.0,
+                total_gb: 0.0,
+            },
+            ..Default::default()
+        });
+        let config = Config::default();
+        let output = MemoryModule.run(&config, &state, &[]).unwrap();
+        assert_eq!(output.class.as_deref(), Some("normal"));
+        assert_eq!(output.percentage, Some(0));
+    }
+}
diff --git a/src/modules/network.rs b/src/modules/network.rs
index ec03055..bbe4b26 100644
--- a/src/modules/network.rs
+++ b/src/modules/network.rs
@@ -2,7 +2,7 @@ use crate::config::Config;
 use crate::modules::WaybarModule;
 use crate::output::WaybarOutput;
 use crate::state::SharedState;
-use crate::utils::{TokenValue, format_template};
+use crate::utils::{TokenValue, format_template, run_command};
 use anyhow::Result;
 use std::fs;
 use std::time::{SystemTime, UNIX_EPOCH};
@@ -148,10 +148,7 @@ impl WaybarModule for NetworkModule {
 }
 
 fn get_primary_interface() -> Result<String> {
-    let output = std::process::Command::new("ip")
-        .args(["route", "list"])
-        .output()?;
-    let stdout = String::from_utf8_lossy(&output.stdout);
+    let stdout = run_command("ip", &["route", "list"])?;
 
     let mut defaults = Vec::new();
     for line in stdout.lines() {
@@ -182,11 +179,7 @@ fn get_primary_interface() -> Result<String> {
 }
 
 fn get_ip_address(interface: &str) -> Option<String> {
-    let output = std::process::Command::new("ip")
-        .args(["-4", "addr", "show", interface])
-        .output()
-        .ok()?;
-    let stdout = String::from_utf8_lossy(&output.stdout);
+    let stdout = run_command("ip", &["-4", "addr", "show", interface]).ok()?;
     for line in stdout.lines() {
         if line.trim().starts_with("inet ") {
             let parts: Vec<&str> = line.split_whitespace().collect();
@@ -217,3 +210,68 @@ fn get_bytes(interface: &str) -> Result<(u64, u64)> {
 
     Ok((rx, tx))
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::state::{AppState, NetworkState, mock_state};
+
+    #[test]
+    fn test_network_no_connection() {
+        let state = mock_state(AppState::default());
+        let config = Config::default();
+        let output = NetworkModule.run(&config, &state, &[]).unwrap();
+        assert_eq!(output.text, "No connection");
+    }
+
+    #[test]
+    fn test_network_connected() {
+        let state = mock_state(AppState {
+            network: NetworkState {
+                rx_mbps: 1.5,
+                tx_mbps: 0.3,
+                interface: "eth0".to_string(),
+                ip: "192.168.1.100".to_string(),
+            },
+            ..Default::default()
+        });
+        let config = Config::default();
+        let output = NetworkModule.run(&config, &state, &[]).unwrap();
+        assert!(output.text.contains("eth0"));
+        assert!(output.text.contains("192.168.1.100"));
+        assert!(output.text.contains("1.50"));
+        assert_eq!(output.class.as_deref(), Some("eth0"));
+    }
+
+    #[test]
+    fn test_network_vpn_prefix() {
+        let state = mock_state(AppState {
+            network: NetworkState {
+                rx_mbps: 0.0,
+                tx_mbps: 0.0,
+                interface: "wg0".to_string(),
+                ip: "10.0.0.1".to_string(),
+            },
+            ..Default::default()
+        });
+        let config = Config::default();
+        let output = NetworkModule.run(&config, &state, &[]).unwrap();
+        assert!(output.text.starts_with("  "));
+    }
+
+    #[test]
+    fn test_network_no_ip() {
+        let state = mock_state(AppState {
+            network: NetworkState {
+                rx_mbps: 0.0,
+                tx_mbps: 0.0,
+                interface: "eth0".to_string(),
+                ip: String::new(),
+            },
+            ..Default::default()
+        });
+        let config = Config::default();
+        let output = NetworkModule.run(&config, &state, &[]).unwrap();
+        assert!(output.text.contains("No IP"));
+    }
+}
diff --git a/src/output.rs b/src/output.rs
index 97c7c02..61617cb 100644
--- a/src/output.rs
+++ b/src/output.rs
@@ -10,3 +10,55 @@ pub struct WaybarOutput {
     #[serde(skip_serializing_if = "Option::is_none")]
     pub percentage: Option<u8>,
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_full_output_serialization() {
+        let output = WaybarOutput {
+            text: "CPU: 50%".to_string(),
+            tooltip: Some("Details".to_string()),
+            class: Some("normal".to_string()),
+            percentage: Some(50),
+        };
+        let json = serde_json::to_string(&output).unwrap();
+        let val: serde_json::Value = serde_json::from_str(&json).unwrap();
+        assert_eq!(val["text"], "CPU: 50%");
+        assert_eq!(val["tooltip"], "Details");
+        assert_eq!(val["class"], "normal");
+        assert_eq!(val["percentage"], 50);
+    }
+
+    #[test]
+    fn test_optional_fields_omitted() {
+        let output = WaybarOutput {
+            text: "test".to_string(),
+            tooltip: None,
+            class: None,
+            percentage: None,
+        };
+        let json = serde_json::to_string(&output).unwrap();
+        let val: serde_json::Value = serde_json::from_str(&json).unwrap();
+        assert_eq!(val["text"], "test");
+        assert!(val.get("tooltip").is_none());
+        assert!(val.get("class").is_none());
+        assert!(val.get("percentage").is_none());
+    }
+
+    #[test]
+    fn test_partial_optional_fields() {
+        let output = WaybarOutput {
+            text: "test".to_string(),
+            tooltip: Some("tip".to_string()),
+            class: None,
+            percentage: Some(75),
+        };
+        let json = serde_json::to_string(&output).unwrap();
+        let val: serde_json::Value = serde_json::from_str(&json).unwrap();
+        assert_eq!(val["tooltip"], "tip");
+        assert!(val.get("class").is_none());
+        assert_eq!(val["percentage"], 75);
+    }
+}
diff --git a/src/state.rs b/src/state.rs
index b520995..29f5082 100644
--- a/src/state.rs
+++ b/src/state.rs
@@ -84,3 +84,8 @@ impl Default for GpuState {
 }
 
 pub type SharedState = Arc<RwLock<AppState>>;
+
+#[cfg(test)]
+pub fn mock_state(state: AppState) -> SharedState {
+    Arc::new(RwLock::new(state))
+}
diff --git a/src/utils.rs b/src/utils.rs
index e1f6835..59e00aa 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -114,3 +114,109 @@ fn format_str(s: &str, align: &str, width: usize) -> String {
         _ => s.to_string(),
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_simple_string_token() {
+        let result = format_template("{name}", &[("name", TokenValue::String("hello"))]);
+        assert_eq!(result, "hello");
+    }
+
+    #[test]
+    fn test_simple_float_token() {
+        let result = format_template("{val}", &[("val", TokenValue::Float(3.15))]);
+        assert_eq!(result, "3.15");
+    }
+
+    #[test]
+    fn test_simple_int_token() {
+        let result = format_template("{count}", &[("count", TokenValue::Int(42))]);
+        assert_eq!(result, "42");
+    }
+
+    #[test]
+    fn test_float_right_align_with_precision() {
+        let result = format_template("{val:>8.2}", &[("val", TokenValue::Float(3.15))]);
+        assert_eq!(result, "    3.15");
+        assert_eq!(result.len(), 8);
+    }
+
+    #[test]
+    fn test_float_left_align_with_precision() {
+        let result = format_template("{val:<8.2}", &[("val", TokenValue::Float(3.15))]);
+        assert_eq!(result, "3.15    ");
+        assert_eq!(result.len(), 8);
+    }
+
+    #[test]
+    fn test_float_center_align_with_precision() {
+        let result = format_template("{val:^8.2}", &[("val", TokenValue::Float(3.15))]);
+        assert_eq!(result, "  3.15  ");
+        assert_eq!(result.len(), 8);
+    }
+
+    #[test]
+    fn test_int_right_align() {
+        let result = format_template("{val:>5}", &[("val", TokenValue::Int(42))]);
+        assert_eq!(result, "   42");
+    }
+
+    #[test]
+    fn test_string_left_align() {
+        let result = format_template("{val:<10}", &[("val", TokenValue::String("hi"))]);
+        assert_eq!(result, "hi        ");
+        assert_eq!(result.len(), 10);
+    }
+
+    #[test]
+    fn test_unknown_token_preserved() {
+        let result = format_template("{unknown}", &[("name", TokenValue::String("test"))]);
+        assert_eq!(result, "{unknown}");
+    }
+
+    #[test]
+    fn test_multiple_tokens() {
+        let result = format_template(
+            "CPU: {usage:>4.1}% {temp:>4.1}C",
+            &[
+                ("usage", TokenValue::Float(55.3)),
+                ("temp", TokenValue::Float(65.0)),
+            ],
+        );
+        assert_eq!(result, "CPU: 55.3% 65.0C");
+    }
+
+    #[test]
+    fn test_no_tokens() {
+        let result = format_template("plain text", &[]);
+        assert_eq!(result, "plain text");
+    }
+
+    #[test]
+    fn test_empty_template() {
+        let result = format_template("", &[("x", TokenValue::Int(1))]);
+        assert_eq!(result, "");
+    }
+
+    #[test]
+    fn test_mixed_token_types() {
+        let result = format_template(
+            "{name} ({ip}): {rx:>5.2} MB/s",
+            &[
+                ("name", TokenValue::String("eth0")),
+                ("ip", TokenValue::String("10.0.0.1")),
+                ("rx", TokenValue::Float(1.5)),
+            ],
+        );
+        assert_eq!(result, "eth0 (10.0.0.1):  1.50 MB/s");
+    }
+
+    #[test]
+    fn test_float_precision_zero() {
+        let result = format_template("{val:>3.0}", &[("val", TokenValue::Float(99.7))]);
+        assert_eq!(result, "100");
+    }
+}