feat: show launcher if different version was installed (#4381)

qt/launcher/build.rs

@@ -7,4 +7,7 @@ fn main() {
             .manifest_required()
             .unwrap();
     }
+    println!("cargo:rerun-if-changed=../../out/buildhash");
+    let buildhash = std::fs::read_to_string("../../out/buildhash").unwrap_or_default();
+    println!("cargo:rustc-env=BUILDHASH={buildhash}");
 }

qt/launcher/src/main.rs

@@ -152,7 +152,9 @@ fn run() -> Result<()> {
     let sync_time = file_timestamp_secs(&state.sync_complete_marker);
     state.pyproject_modified_by_user = pyproject_time > sync_time;
     let pyproject_has_changed = state.pyproject_modified_by_user;
-    if !launcher_requested && !pyproject_has_changed {
+    let different_launcher = diff_launcher_was_installed(&state)?;
+
+    if !launcher_requested && !pyproject_has_changed && !different_launcher {
         // If no launcher request and venv is already up to date, launch Anki normally
         let args: Vec<String> = std::env::args().skip(1).collect();
         let cmd = build_python_command(&state, &args)?;
@@ -1107,6 +1109,20 @@ fn show_mirror_submenu(state: &State) -> Result<()> {
     Ok(())
 }
 
+fn diff_launcher_was_installed(state: &State) -> Result<bool> {
+    let launcher_version = option_env!("BUILDHASH").unwrap_or("dev").trim();
+    let launcher_version_path = state.uv_install_root.join("launcher-version");
+    if let Ok(content) = read_file(&launcher_version_path) {
+        if let Ok(version_str) = String::from_utf8(content) {
+            if version_str.trim() == launcher_version {
+                return Ok(false);
+            }
+        }
+    }
+    write_file(launcher_version_path, launcher_version)?;
+    Ok(true)
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;