fix: isolate debug runtime paths and block duplicate herdr instances

4 files changed, 66 insertions, 33 deletions

diff --git a/src/api/mod.rs b/src/api/mod.rs
index 2e7692a4..1a713323 100644
--- a/src/api/mod.rs
+++ b/src/api/mod.rs
@@ -71,19 +71,17 @@ pub fn socket_path() -> PathBuf {
         return PathBuf::from(path);
     }
 
-    if let Ok(dir) = std::env::var("XDG_RUNTIME_DIR") {
-        return PathBuf::from(dir).join("herdr.sock");
-    }
-
-    if let Ok(dir) = std::env::var("XDG_CONFIG_HOME") {
-        return PathBuf::from(dir).join("herdr/herdr.sock");
-    }
+    let socket_name = if crate::config::app_dir_name() == "herdr" {
+        "herdr.sock"
+    } else {
+        "herdr-dev.sock"
+    };
 
-    if let Ok(home) = std::env::var("HOME") {
-        return PathBuf::from(home).join(".config/herdr/herdr.sock");
+    if let Ok(dir) = std::env::var("XDG_RUNTIME_DIR") {
+        return PathBuf::from(dir).join(socket_name);
     }
 
-    PathBuf::from("/tmp/herdr.sock")
+    crate::config::config_dir().join("herdr.sock")
 }
 
 pub struct ServerHandle {
@@ -143,6 +141,30 @@ fn prepare_socket_path(path: &Path) -> std::io::Result<()> {
         fs::create_dir_all(parent)?;
     }
 
+    if !path.exists() {
+        return Ok(());
+    }
+
+    match UnixStream::connect(path) {
+        Ok(_) => {
+            return Err(std::io::Error::new(
+                std::io::ErrorKind::AddrInUse,
+                format!(
+                    "herdr is already running (socket busy at {})",
+                    path.display()
+                ),
+            ));
+        }
+        Err(err)
+            if matches!(
+                err.kind(),
+                std::io::ErrorKind::ConnectionRefused
+                    | std::io::ErrorKind::NotFound
+                    | std::io::ErrorKind::TimedOut
+            ) => {}
+        Err(err) => return Err(err),
+    }
+
     if let Err(err) = fs::remove_file(path) {
         if err.kind() != std::io::ErrorKind::NotFound {
             return Err(err);
diff --git a/src/config.rs b/src/config.rs
index c901c2d6..d5417421 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -6,6 +6,24 @@ use serde::Deserialize;
 pub const CONFIG_PATH_ENV_VAR: &str = "HERDR_CONFIG_PATH";
 use tracing::warn;
 
+pub fn app_dir_name() -> &'static str {
+    if cfg!(debug_assertions) {
+        "herdr-dev"
+    } else {
+        "herdr"
+    }
+}
+
+pub fn config_dir() -> PathBuf {
+    if let Ok(dir) = std::env::var("XDG_CONFIG_HOME") {
+        PathBuf::from(dir).join(app_dir_name())
+    } else if let Ok(home) = std::env::var("HOME") {
+        PathBuf::from(home).join(format!(".config/{}", app_dir_name()))
+    } else {
+        PathBuf::from(format!("/tmp/{}", app_dir_name()))
+    }
+}
+
 use crate::detect::Agent;
 
 #[derive(Debug, Clone, Deserialize)]
@@ -705,13 +723,7 @@ pub fn config_path() -> PathBuf {
     if let Ok(path) = std::env::var(CONFIG_PATH_ENV_VAR) {
         return PathBuf::from(path);
     }
-    if let Ok(dir) = std::env::var("XDG_CONFIG_HOME") {
-        PathBuf::from(dir).join("herdr/config.toml")
-    } else if let Ok(home) = std::env::var("HOME") {
-        PathBuf::from(home).join(".config/herdr/config.toml")
-    } else {
-        PathBuf::from("/tmp/herdr/config.toml")
-    }
+    config_dir().join("config.toml")
 }
 
 fn upsert_top_level_bool(content: &str, key: &str, value: bool) -> String {
diff --git a/src/main.rs b/src/main.rs
index 385f6f5f..ee72e49b 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -43,13 +43,7 @@ fn init_logging() {
     use std::fs::{self, OpenOptions};
     use tracing_subscriber::EnvFilter;
 
-    let log_dir = if let Ok(dir) = std::env::var("XDG_CONFIG_HOME") {
-        std::path::PathBuf::from(dir).join("herdr")
-    } else if let Ok(home) = std::env::var("HOME") {
-        std::path::PathBuf::from(home).join(".config/herdr")
-    } else {
-        std::path::PathBuf::from("/tmp/herdr")
-    };
+    let log_dir = crate::config::config_dir();
     let _ = fs::create_dir_all(&log_dir);
     let log_path = log_dir.join("herdr.log");
 
@@ -218,7 +212,10 @@ fn main() -> io::Result<()> {
         println!("  --help, -h          Show this help");
         println!();
         println!("Config: {}", config::config_path().display());
-        println!("Logs:   ~/.config/herdr/herdr.log");
+        println!(
+            "Logs:   {}",
+            config::config_dir().join("herdr.log").display()
+        );
         println!("Env:    HERDR_CONFIG_PATH overrides config file path");
         println!("Home:   https://herdr.dev");
         return Ok(());
@@ -272,7 +269,15 @@ fn main() -> io::Result<()> {
 
     let (api_tx, api_rx) = tokio::sync::mpsc::unbounded_channel();
     let event_hub = api::EventHub::default();
-    let _api_server = api::start_server(api_tx, event_hub.clone())?;
+    let _api_server = match api::start_server(api_tx, event_hub.clone()) {
+        Ok(server) => server,
+        Err(err) if err.kind() == io::ErrorKind::AddrInUse => {
+            eprintln!("error: herdr is already running");
+            eprintln!("socket: {}", api::socket_path().display());
+            std::process::exit(1);
+        }
+        Err(err) => return Err(err),
+    };
 
     let no_session = std::env::args().any(|a| a == "--no-session");
     let show_changelog = std::env::args().any(|a| a == "--show-changelog");
diff --git a/src/persist.rs b/src/persist.rs
index c296b0ac..fb8ab2d8 100644
--- a/src/persist.rs
+++ b/src/persist.rs
@@ -467,13 +467,7 @@ fn collect_ids_inner(node: &Node, ids: &mut Vec<PaneId>) {
 // --- File I/O ---
 
 fn session_path() -> PathBuf {
-    if let Ok(dir) = std::env::var("XDG_CONFIG_HOME") {
-        PathBuf::from(dir).join("herdr/session.json")
-    } else if let Ok(home) = std::env::var("HOME") {
-        PathBuf::from(home).join(".config/herdr/session.json")
-    } else {
-        PathBuf::from("/tmp/herdr/session.json")
-    }
+    crate::config::config_dir().join("session.json")
 }
 
 pub fn save(snapshot: &SessionSnapshot) {