From 1daf54ecbf960c42d612ed4ad2764045a606fb30 Mon Sep 17 00:00:00 2001
From: Golden-Pigeon <goldenpigeon2000@gmail.com>
Date: Fri, 22 May 2026 02:39:02 +0300
Subject: feat: show named session command hints

refs #199
---
 src/client/mod.rs | 115 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 114 insertions(+), 1 deletion(-)

(limited to 'src/client')

diff --git a/src/client/mod.rs b/src/client/mod.rs
index 11273061..1ac05201 100644
--- a/src/client/mod.rs
+++ b/src/client/mod.rs
@@ -154,7 +154,11 @@ impl std::fmt::Display for ClientError {
                             write!(f, "\nRun `{reattach_command}` to reattach")?;
                         } else {
                             write!(f, "detached from server")?;
-                            write!(f, "\nRun `herdr` to reattach")?;
+                            write!(
+                                f,
+                                "\nRun `{}` to reattach",
+                                crate::session::local_attach_command()
+                            )?;
                         }
                     }
                     _ => {
@@ -1125,6 +1129,65 @@ fn init_logging() {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use std::ffi::OsString;
+    use std::sync::{Mutex, OnceLock};
+
+    fn env_lock() -> &'static Mutex<()> {
+        static LOCK: OnceLock<Mutex<()>> = OnceLock::new();
+        LOCK.get_or_init(|| Mutex::new(()))
+    }
+
+    fn restore_env_var(key: &str, value: Option<OsString>) {
+        if let Some(value) = value {
+            std::env::set_var(key, value);
+        } else {
+            std::env::remove_var(key);
+        }
+    }
+
+    struct EnvVarGuard {
+        key: &'static str,
+        previous: Option<OsString>,
+    }
+
+    impl EnvVarGuard {
+        fn set(key: &'static str, value: &str) -> Self {
+            let previous = std::env::var_os(key);
+            std::env::set_var(key, value);
+            Self { key, previous }
+        }
+    }
+
+    impl Drop for EnvVarGuard {
+        fn drop(&mut self) {
+            restore_env_var(self.key, self.previous.clone());
+        }
+    }
+
+    struct EnvVarsRemovedGuard {
+        previous: Vec<(&'static str, Option<OsString>)>,
+    }
+
+    impl EnvVarsRemovedGuard {
+        fn new(keys: &[&'static str]) -> Self {
+            let previous: Vec<_> = keys
+                .iter()
+                .map(|key| (*key, std::env::var_os(key)))
+                .collect();
+            for key in keys {
+                std::env::remove_var(key);
+            }
+            Self { previous }
+        }
+    }
+
+    impl Drop for EnvVarsRemovedGuard {
+        fn drop(&mut self) {
+            for (key, value) in self.previous.clone() {
+                restore_env_var(key, value);
+            }
+        }
+    }
 
     #[test]
     fn clipboard_image_paste_bridge_triggers_on_ctrl_v_and_empty_paste() {
@@ -1295,6 +1358,56 @@ mod tests {
         );
     }
 
+    #[test]
+    fn client_error_display_detached_default_session_reattach_hint() {
+        let _guard = env_lock().lock().unwrap();
+        let _env = EnvVarsRemovedGuard::new(&[
+            crate::remote::REATTACH_COMMAND_ENV_VAR,
+            crate::session::SESSION_ENV_VAR,
+        ]);
+        let err = ClientError::ServerShutdown {
+            reason: Some("detached".into()),
+        };
+        let msg = err.to_string();
+        assert!(
+            msg.contains("Run `herdr` to reattach"),
+            "should suggest default reattach command: {msg}"
+        );
+    }
+
+    #[test]
+    fn client_error_display_detached_named_session_reattach_hint() {
+        let _guard = env_lock().lock().unwrap();
+        let _remote_env = EnvVarsRemovedGuard::new(&[crate::remote::REATTACH_COMMAND_ENV_VAR]);
+        let _session_env = EnvVarGuard::set(crate::session::SESSION_ENV_VAR, "work");
+        let err = ClientError::ServerShutdown {
+            reason: Some("detached".into()),
+        };
+        let msg = err.to_string();
+        assert!(
+            msg.contains("Run `herdr session attach work` to reattach"),
+            "should suggest named session reattach command: {msg}"
+        );
+    }
+
+    #[test]
+    fn client_error_display_detached_remote_reattach_hint_takes_precedence() {
+        let _guard = env_lock().lock().unwrap();
+        let _remote_env = EnvVarGuard::set(
+            crate::remote::REATTACH_COMMAND_ENV_VAR,
+            "herdr --remote host --session work",
+        );
+        let _session_env = EnvVarGuard::set(crate::session::SESSION_ENV_VAR, "work");
+        let err = ClientError::ServerShutdown {
+            reason: Some("detached".into()),
+        };
+        let msg = err.to_string();
+        assert!(
+            msg.contains("Run `herdr --remote host --session work` to reattach"),
+            "should prefer remote reattach command: {msg}"
+        );
+    }
+
     #[test]
     fn client_error_display_connection_lost() {
         let err =
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