diff --git a/Cargo.lock b/Cargo.lock
index dd83245..421bc47 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -19,12 +19,10 @@ dependencies = [
  "ahfail-ui",
  "gdk",
  "gdk-pixbuf",
- "gio",
  "glib",
  "gstreamer",
  "gstreamer-player",
  "gtk",
- "libc",
  "pkg-config",
  "rand",
 ]
@@ -44,7 +42,9 @@ dependencies = [
  "gstreamer",
  "gstreamer-player",
  "gtk",
+ "libc",
  "rand",
+ "tempfile",
  "ureq",
 ]
 
@@ -61,7 +61,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2c3d816ce6f0e2909a96830d6911c2aff044370b1ef92d7f267b43bae5addedd"
 dependencies = [
  "atk-sys",
- "bitflags",
+ "bitflags 1.3.2",
  "glib",
  "libc",
 ]
@@ -96,13 +96,19 @@ version = "1.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
 
+[[package]]
+name = "bitflags"
+version = "2.11.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c4512299f36f043ab09a583e57bceb5a5aab7a73db1805848e8fef3c9e8c78b3"
+
 [[package]]
 name = "cairo-rs"
 version = "0.15.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c76ee391b03d35510d9fa917357c7f1855bd9a6659c95a1b392e33f49b3369bc"
 dependencies = [
- "bitflags",
+ "bitflags 1.3.2",
  "cairo-sys-rs",
  "glib",
  "libc",
@@ -172,6 +178,22 @@ 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 = "2.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9f1f227452a390804cdb637b74a86990f2a7d7ba4b7d5693aac9b4dd6defd8d6"
+
 [[package]]
 name = "field-offset"
 version = "0.3.6"
@@ -198,6 +220,12 @@ dependencies = [
  "miniz_oxide",
 ]
 
+[[package]]
+name = "foldhash"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d9c4f5dac5e15c24eb999c26181a6ca40b39fe946cbe4c263c7209467bc83af2"
+
 [[package]]
 name = "form_urlencoded"
 version = "1.2.2"
@@ -264,7 +292,7 @@ version = "0.15.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a6e05c1f572ab0e1f15be94217f0dc29088c248b14f792a5ff0af0d84bcda9e8"
 dependencies = [
- "bitflags",
+ "bitflags 1.3.2",
  "cairo-rs",
  "gdk-pixbuf",
  "gdk-sys",
@@ -280,7 +308,7 @@ version = "0.15.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ad38dd9cc8b099cceecdf41375bb6d481b1b5a7cd5cd603e10a69a9383f8619a"
 dependencies = [
- "bitflags",
+ "bitflags 1.3.2",
  "gdk-pixbuf-sys",
  "gio",
  "glib",
@@ -328,13 +356,26 @@ dependencies = [
  "wasi",
 ]
 
+[[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 = "gio"
 version = "0.15.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "68fdbc90312d462781a395f7a16d96a2b379bb6ef8cd6310a2df272771c4283b"
 dependencies = [
- "bitflags",
+ "bitflags 1.3.2",
  "futures-channel",
  "futures-core",
  "futures-io",
@@ -364,7 +405,7 @@ version = "0.15.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "edb0306fbad0ab5428b0ca674a23893db909a98582969c9b537be4ced78c505d"
 dependencies = [
- "bitflags",
+ "bitflags 1.3.2",
  "futures-channel",
  "futures-core",
  "futures-executor",
@@ -420,7 +461,7 @@ version = "0.18.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d66363bacf5e4f6eb281564adc2902e44c52ae5c45082423e7439e9012b75456"
 dependencies = [
- "bitflags",
+ "bitflags 1.3.2",
  "cfg-if",
  "futures-channel",
  "futures-core",
@@ -444,7 +485,7 @@ version = "0.18.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "224f35f36582407caf58ded74854526beeecc23d0cf64b8d1c3e00584ed6863f"
 dependencies = [
- "bitflags",
+ "bitflags 1.3.2",
  "cfg-if",
  "glib",
  "gstreamer",
@@ -471,7 +512,7 @@ version = "0.18.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5f14ee02352ba73cadebe640bfb33f12fe8d03cbcad816a102d55a0251fb99bb"
 dependencies = [
- "bitflags",
+ "bitflags 1.3.2",
  "glib",
  "gstreamer",
  "gstreamer-player-sys",
@@ -512,7 +553,7 @@ version = "0.18.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9418adfc72dafa1ad9eb106527ce4804887d101027c4528ec28c7d29cc899519"
 dependencies = [
- "bitflags",
+ "bitflags 1.3.2",
  "cfg-if",
  "futures-channel",
  "glib",
@@ -544,7 +585,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "92e3004a2d5d6d8b5057d2b57b3712c9529b62e82c77f25c1fecde1fd5c23bd0"
 dependencies = [
  "atk",
- "bitflags",
+ "bitflags 1.3.2",
  "cairo-rs",
  "field-offset",
  "futures-channel",
@@ -592,6 +633,15 @@ dependencies = [
  "syn 1.0.109",
 ]
 
+[[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"
@@ -691,6 +741,12 @@ dependencies = [
  "zerovec",
 ]
 
+[[package]]
+name = "id-arena"
+version = "2.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3d3067d79b975e8844ca9eb072e16b31c3c1c36928edf9c6789548c524d0d954"
+
 [[package]]
 name = "idna"
 version = "1.1.0"
@@ -719,15 +775,35 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0ad4bb2b565bca0645f4d68c5c9af97fba094e9791da685bf83cb5f3ce74acf2"
 dependencies = [
  "equivalent",
- "hashbrown",
+ "hashbrown 0.16.1",
+ "serde",
+ "serde_core",
 ]
 
+[[package]]
+name = "itoa"
+version = "1.0.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8f42a60cbdf9a97f5d2305f08a87dc4e09308d1276d28c869c684d7777685682"
+
+[[package]]
+name = "leb128fmt"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "09edd9e8b54e49e587e4f6295a7d29c3ea94d469cb40ab8ca70b288248a81db2"
+
 [[package]]
 name = "libc"
 version = "0.2.177"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2874a2af47a2325c2001a6e6fad9b16a53b802102b528163885171cf92b15976"
 
+[[package]]
+name = "linux-raw-sys"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "df1d3c3b53da64cf5760482273a98e575c651a67eec7f77df96b5b642de8f039"
+
 [[package]]
 name = "litemap"
 version = "0.8.2"
@@ -820,7 +896,7 @@ version = "0.15.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "22e4045548659aee5313bde6c582b0d83a627b7904dd20dc2d9ef0895d414e4f"
 dependencies = [
- "bitflags",
+ "bitflags 1.3.2",
  "glib",
  "libc",
  "once_cell",
@@ -893,6 +969,16 @@ version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c6fa0831dd7cc608c38a5e323422a0077678fa5744aa2be4ad91c4ece8eec8d5"
 
+[[package]]
+name = "prettyplease"
+version = "0.2.37"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "479ca8adacdd7ce8f1fb39ce9ecccbfe93a3f1344b3d0d97f20bc0196208f62b"
+dependencies = [
+ "proc-macro2",
+ "syn 2.0.111",
+]
+
 [[package]]
 name = "proc-macro-crate"
 version = "1.3.1"
@@ -945,6 +1031,12 @@ 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 = "rand"
 version = "0.8.5"
@@ -972,7 +1064,7 @@ version = "0.6.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
 dependencies = [
- "getrandom",
+ "getrandom 0.2.16",
 ]
 
 [[package]]
@@ -983,7 +1075,7 @@ checksum = "a4689e6c2294d81e88dc6261c768b63bc4fcdb852be6d1352498b114f61383b7"
 dependencies = [
  "cc",
  "cfg-if",
- "getrandom",
+ "getrandom 0.2.16",
  "libc",
  "untrusted",
  "windows-sys",
@@ -998,6 +1090,19 @@ dependencies = [
  "semver",
 ]
 
+[[package]]
+name = "rustix"
+version = "1.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "146c9e247ccc180c1f61615433868c99f3de3ae256a30a43b49f67c2d9171f34"
+dependencies = [
+ "bitflags 2.11.1",
+ "errno",
+ "libc",
+ "linux-raw-sys",
+ "windows-sys",
+]
+
 [[package]]
 name = "rustls"
 version = "0.23.40"
@@ -1068,6 +1173,19 @@ dependencies = [
  "syn 2.0.111",
 ]
 
+[[package]]
+name = "serde_json"
+version = "1.0.149"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "83fc039473c5595ace860d8c4fafa220ff474b3fc6bfdb4293327f1a37e94d86"
+dependencies = [
+ "itoa",
+ "memchr",
+ "serde",
+ "serde_core",
+ "zmij",
+]
+
 [[package]]
 name = "serde_spanned"
 version = "0.6.9"
@@ -1165,6 +1283,19 @@ version = "0.12.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "61c41af27dd6d1e27b1b16b489db798443478cef1f06a660c96db617ba5de3b1"
 
+[[package]]
+name = "tempfile"
+version = "3.25.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0136791f7c95b1f6dd99f9cc786b91bb81c3800b639b3478e561ddb7be95e5f1"
+dependencies = [
+ "fastrand",
+ "getrandom 0.4.2",
+ "once_cell",
+ "rustix",
+ "windows-sys",
+]
+
 [[package]]
 name = "thiserror"
 version = "1.0.69"
@@ -1246,6 +1377,12 @@ version = "1.0.22"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9312f7c4f6ff9069b165498234ce8be658059c6728633667c526e27dc2cf1df5"
 
+[[package]]
+name = "unicode-xid"
+version = "0.2.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ebc1c04c71510c7f702b52b7c350734c9ff1295c464a03335b00bb84fc54f853"
+
 [[package]]
 name = "untrusted"
 version = "0.9.0"
@@ -1304,6 +1441,58 @@ version = "0.11.1+wasi-snapshot-preview1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ccf3ec651a847eb01de73ccad15eb7d99f80485de043efb2f370cd654f4ea44b"
 
+[[package]]
+name = "wasip2"
+version = "1.0.3+wasi-0.2.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "20064672db26d7cdc89c7798c48a0fdfac8213434a1186e5ef29fd560ae223d6"
+dependencies = [
+ "wit-bindgen 0.57.1",
+]
+
+[[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 0.51.0",
+]
+
+[[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 2.11.1",
+ "hashbrown 0.15.5",
+ "indexmap",
+ "semver",
+]
+
 [[package]]
 name = "webpki-roots"
 version = "0.26.11"
@@ -1435,6 +1624,100 @@ dependencies = [
  "memchr",
 ]
 
+[[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"
+version = "0.57.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1ebf944e87a7c253233ad6766e082e3cd714b5d03812acc24c318f549614536e"
+
+[[package]]
+name = "wit-bindgen-core"
+version = "0.51.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ea61de684c3ea68cb082b7a88508a8b27fcc8b797d738bfc99a82facf1d752dc"
+dependencies = [
+ "anyhow",
+ "heck 0.5.0",
+ "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 0.5.0",
+ "indexmap",
+ "prettyplease",
+ "syn 2.0.111",
+ "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 2.0.111",
+ "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 2.11.1",
+ "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 = "writeable"
 version = "0.6.3"
@@ -1543,3 +1826,9 @@ dependencies = [
  "quote",
  "syn 2.0.111",
 ]
+
+[[package]]
+name = "zmij"
+version = "1.0.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b8848ee67ecc8aedbaf3e4122217aff892639231befc6a1b58d29fff4c2cabaa"
diff --git a/crates/ahfail-gtklock/src/handler.rs b/crates/ahfail-gtklock/src/handler.rs
index a8b2ee9..5aadc81 100644
--- a/crates/ahfail-gtklock/src/handler.rs
+++ b/crates/ahfail-gtklock/src/handler.rs
@@ -56,6 +56,13 @@ impl WindowHandler {
             }
             println!("[ahfail] Error label changed to: '{}'", text_str);
 
+            MODULE_STATE.with(|s| {
+                let mut st = s.borrow_mut();
+                if st.volume_state.is_none() {
+                    st.volume_state = ahfail_ui::volume::save_and_set_max();
+                }
+            });
+
             MODULE_STATE.with(|state| {
                 let state = state.borrow();
                 if let (Some(animation), Some(audio_uri)) = (&state.animation, &state.audio_uri) {
diff --git a/crates/ahfail-gtklock/src/lib.rs b/crates/ahfail-gtklock/src/lib.rs
index b105377..7838ce9 100644
--- a/crates/ahfail-gtklock/src/lib.rs
+++ b/crates/ahfail-gtklock/src/lib.rs
@@ -136,8 +136,12 @@ pub unsafe extern "C" fn on_idle_show(_gtklock: *mut GtkLock) {}
 pub unsafe extern "C" fn g_module_unload(_module: *mut c_void) {
     MODULE_STATE.with(|state| {
         let mut state = state.borrow_mut();
+        if let Some(vs) = state.volume_state.take() {
+            ahfail_ui::volume::restore(vs);
+        }
         state.animation = None;
         state.audio_uri = None;
         state.config.deadzone = None;
+        state.volume_state = None;
     });
 }
\ No newline at end of file
diff --git a/crates/ahfail-gtklock/src/state.rs b/crates/ahfail-gtklock/src/state.rs
index 1367b21..be347d2 100644
--- a/crates/ahfail-gtklock/src/state.rs
+++ b/crates/ahfail-gtklock/src/state.rs
@@ -7,6 +7,7 @@ pub struct ModuleState {
     pub animation: Option<gdk_pixbuf::PixbufAnimation>,
     pub audio_uri: Option<String>,
     pub config: ModuleConfig,
+    pub volume_state: Option<ahfail_ui::volume::VolumeState>,
 }
 
 pub struct WindowData {
@@ -22,5 +23,6 @@ thread_local! {
         animation: None,
         audio_uri: None,
         config: ModuleConfig { deadzone: None },
+        volume_state: None,
     }) };
 }
diff --git a/crates/ahfail-ui/Cargo.toml b/crates/ahfail-ui/Cargo.toml
index 4e5df87..7097b94 100644
--- a/crates/ahfail-ui/Cargo.toml
+++ b/crates/ahfail-ui/Cargo.toml
@@ -17,3 +17,7 @@ gio = { version = "0.15", package = "gio" }
 gdk-pixbuf = "0.15"
 rand = "0.8"
 ureq = "2"
+libc = "0.2"
+
+[dev-dependencies]
+tempfile = "3"
diff --git a/crates/ahfail-ui/src/volume.rs b/crates/ahfail-ui/src/volume.rs
index ef8336b..7b3745f 100644
--- a/crates/ahfail-ui/src/volume.rs
+++ b/crates/ahfail-ui/src/volume.rs
@@ -1,7 +1,139 @@
-pub struct VolumeState;
+use std::path::PathBuf;
+use std::process::Command;
+use std::fs;
+use std::io::Write;
 
-pub fn save_and_set_max() -> Option<VolumeState> {
-    None
+pub struct VolumeState {
+    pub volume: u32,
+    pub muted: bool,
+    pub lock_path: PathBuf,
 }
 
-pub fn restore(_state: VolumeState) {}
+/// Atomically creates lock file. Returns true if this process is first (primary).
+pub fn try_acquire_lock(path: &std::path::Path) -> bool {
+    fs::OpenOptions::new()
+        .write(true)
+        .create_new(true)
+        .open(path)
+        .map(|mut f| { let _ = f.write_all(b"1"); true })
+        .unwrap_or(false)
+}
+
+/// Returns lock file path: $XDG_RUNTIME_DIR/ahfail.lock or /tmp/ahfail-{uid}.lock
+pub fn lock_path() -> PathBuf {
+    if let Ok(dir) = std::env::var("XDG_RUNTIME_DIR") {
+        PathBuf::from(dir).join("ahfail.lock")
+    } else {
+        PathBuf::from(format!("/tmp/ahfail-{}.lock", get_uid()))
+    }
+}
+
+fn get_uid() -> u32 {
+    unsafe { libc::getuid() }
+}
+
+/// If primary: save current system volume/mute state, set volume to 100% unmuted.
+/// Returns Some(VolumeState) if this process is the primary (should restore on exit).
+pub fn save_and_set_max() -> Option<VolumeState> {
+    let path = lock_path();
+    if !try_acquire_lock(&path) { return None; }
+    let (volume, muted) = get_current_volume();
+    set_volume_max();
+    Some(VolumeState { volume, muted, lock_path: path })
+}
+
+/// Restores volume from saved state and removes lock file.
+pub fn restore(state: VolumeState) {
+    restore_volume(state.volume, state.muted);
+    let _ = fs::remove_file(&state.lock_path);
+}
+
+#[cfg(target_os = "linux")]
+fn get_current_volume() -> (u32, bool) {
+    let vol = Command::new("pactl")
+        .args(["get-sink-volume", "@DEFAULT_SINK@"])
+        .output()
+        .ok()
+        .and_then(|o| parse_pactl_volume(&String::from_utf8_lossy(&o.stdout)))
+        .unwrap_or(100);
+
+    let muted = Command::new("pactl")
+        .args(["get-sink-mute", "@DEFAULT_SINK@"])
+        .output()
+        .ok()
+        .map(|o| String::from_utf8_lossy(&o.stdout).contains("yes"))
+        .unwrap_or(false);
+
+    (vol, muted)
+}
+
+#[cfg(target_os = "linux")]
+fn parse_pactl_volume(output: &str) -> Option<u32> {
+    output.split('%').next()
+        .and_then(|s| s.split_whitespace().last())
+        .and_then(|s| s.parse().ok())
+}
+
+#[cfg(target_os = "linux")]
+fn set_volume_max() {
+    let _ = Command::new("pactl").args(["set-sink-mute", "@DEFAULT_SINK@", "0"]).status();
+    let _ = Command::new("pactl").args(["set-sink-volume", "@DEFAULT_SINK@", "65536"]).status();
+}
+
+#[cfg(target_os = "linux")]
+fn restore_volume(volume: u32, muted: bool) {
+    let v = ((volume as u64 * 65536) / 100) as u32;
+    let _ = Command::new("pactl")
+        .args(["set-sink-volume", "@DEFAULT_SINK@", &v.to_string()])
+        .status();
+    let mute_arg = if muted { "1" } else { "0" };
+    let _ = Command::new("pactl").args(["set-sink-mute", "@DEFAULT_SINK@", mute_arg]).status();
+}
+
+#[cfg(target_os = "macos")]
+fn get_current_volume() -> (u32, bool) {
+    let output = Command::new("osascript")
+        .args(["-e", "output volume of (get volume settings)"])
+        .output()
+        .ok();
+    let vol = output.as_ref()
+        .and_then(|o| String::from_utf8_lossy(&o.stdout).trim().parse().ok())
+        .unwrap_or(100);
+
+    let muted = Command::new("osascript")
+        .args(["-e", "output muted of (get volume settings)"])
+        .output()
+        .ok()
+        .map(|o| String::from_utf8_lossy(&o.stdout).trim() == "true")
+        .unwrap_or(false);
+
+    (vol, muted)
+}
+
+#[cfg(target_os = "macos")]
+fn set_volume_max() {
+    let _ = Command::new("osascript")
+        .args(["-e", "set volume output volume 100 without output muted"])
+        .status();
+}
+
+#[cfg(target_os = "macos")]
+fn restore_volume(volume: u32, muted: bool) {
+    let script = if muted {
+        format!("set volume output volume {} with output muted", volume)
+    } else {
+        format!("set volume output volume {} without output muted", volume)
+    };
+    let _ = Command::new("osascript").args(["-e", &script]).status();
+}
+
+#[cfg(not(any(target_os = "linux", target_os = "macos")))]
+fn get_current_volume() -> (u32, bool) {
+    (100, false)
+}
+
+#[cfg(not(any(target_os = "linux", target_os = "macos")))]
+fn set_volume_max() {}
+
+#[cfg(not(any(target_os = "linux", target_os = "macos")))]
+fn restore_volume(_volume: u32, _muted: bool) {}
diff --git a/crates/ahfail-ui/tests/volume_tests.rs b/crates/ahfail-ui/tests/volume_tests.rs
new file mode 100644
index 0000000..1708ac2
--- /dev/null
+++ b/crates/ahfail-ui/tests/volume_tests.rs
@@ -0,0 +1,12 @@
+#[test]
+fn lock_file_created_and_prevents_second_acquisition() {
+    let dir = tempfile::tempdir().unwrap();
+    let lock_path = dir.path().join("ahfail.lock");
+
+    let acquired = ahfail_ui::volume::try_acquire_lock(&lock_path);
+    assert!(acquired);
+    assert!(lock_path.exists());
+
+    let acquired2 = ahfail_ui::volume::try_acquire_lock(&lock_path);
+    assert!(!acquired2);
+}