feat(doctor): detect active preexec framework (#1955)

* feat(doctor): check active preexec framework

To check if "blesh" or "bash-preexec" is loaded and active in the
current Bash session where `atuin doctor` is called, we make the Atuin
integration script for Bash to set the environment variable
`ATUIN_PREEXEC_BACKEND` and store a string when it detects "blesh" or
"bash-preexec".

To check whether the obtained ATUIN_PREEXEC_BACKEND is set by the
current session, we record SHLVL in ATUIN_PREEXEC_BACKEND and check if
it matches SHLVL of the current process.

* feat(doctor): detect the case where Atuin is initialized before blesh

atuin/src/command/client/doctor.rs

@@ -19,6 +19,9 @@ struct ShellInfo {
     // Detect some shell plugins that the user has installed.
     // I'm just going to start with preexec/blesh
     pub plugins: Vec<String>,
+
+    // The preexec framework used in the current session, if Atuin is loaded.
+    pub preexec: Option<String>,
 }
 
 impl ShellInfo {
@@ -43,6 +46,31 @@ impl ShellInfo {
         cmd.contains("ATUIN_DOCTOR_ENV_FOUND")
     }
 
+    fn detect_preexec_framework(shell: &str) -> Option<String> {
+        if env::var("ATUIN_SESSION").ok().is_none() {
+            None
+        } else if shell.starts_with("bash") || shell == "sh" {
+            env::var("ATUIN_PREEXEC_BACKEND")
+                .ok()
+                .filter(|value| !value.is_empty())
+                .and_then(|atuin_preexec_backend| {
+                    atuin_preexec_backend.rfind(':').and_then(|pos_colon| {
+                        u32::from_str(&atuin_preexec_backend[..pos_colon])
+                            .ok()
+                            .is_some_and(|preexec_shlvl| {
+                                env::var("SHLVL")
+                                    .ok()
+                                    .and_then(|shlvl| u32::from_str(&shlvl).ok())
+                                    .is_some_and(|shlvl| shlvl == preexec_shlvl)
+                            })
+                            .then(|| atuin_preexec_backend[pos_colon + 1..].to_string())
+                    })
+                })
+        } else {
+            Some("built-in".to_string())
+        }
+    }
+
     fn validate_plugin_blesh(
         _shell: &str,
         shell_process: &sysinfo::Process,
@@ -156,10 +184,13 @@ impl ShellInfo {
 
         let default = Shell::default_shell().unwrap_or(Shell::Unknown).to_string();
 
+        let preexec = Self::detect_preexec_framework(name.as_str());
+
         Self {
             name,
             default,
             plugins,
+            preexec,
         }
     }
 }
@@ -272,6 +303,7 @@ fn checks(info: &DoctorDump) {
                 //
     let zfs_error = "[Filesystem] ZFS is known to have some issues with SQLite. Atuin uses SQLite heavily. If you are having poor performance, there are some workarounds here: https://github.com/atuinsh/atuin/issues/952".bold().red();
     let bash_plugin_error = "[Shell] If you are using Bash, Atuin requires that either bash-preexec or ble.sh be installed. An older ble.sh may not be detected. so ignore this if you have it set up! Read more here: https://docs.atuin.sh/guide/installation/#bash".bold().red();
+    let blesh_loading_order_error = "[Shell] Atuin seems to be loaded before ble.sh is sourced. In .bashrc, make sure to initialize Atuin after sourcing ble.sh.".bold().red();
 
     // ZFS: https://github.com/atuinsh/atuin/issues/952
     if info.system.disks.iter().any(|d| d.filesystem == "zfs") {
@@ -279,8 +311,8 @@ fn checks(info: &DoctorDump) {
     }
 
     // Shell
-    if info.shell.name == "bash"
-        && !info
+    if info.shell.name == "bash" {
+        if !info
             .shell
             .plugins
             .iter()
@@ -288,6 +320,14 @@ fn checks(info: &DoctorDump) {
         {
             println!("{bash_plugin_error}");
         }
+
+        if info.shell.plugins.iter().any(|plugin| plugin == "atuin")
+            && info.shell.plugins.iter().any(|plugin| plugin == "blesh")
+            && info.shell.preexec.as_ref().is_some_and(|val| val == "none")
+        {
+            println!("{blesh_loading_order_error}");
+        }
+    }
 }
 
 pub fn run(settings: &Settings) -> Result<()> {

atuin/src/shell/atuin.bash

@@ -17,6 +17,19 @@ ATUIN_STTY=$(stty -g)
 export ATUIN_SESSION
 ATUIN_HISTORY_ID=""
 
+export ATUIN_PREEXEC_BACKEND=$SHLVL:none
+__atuin_update_preexec_backend() {
+    if [[ ${BLE_ATTACHED-} ]]; then
+        ATUIN_PREEXEC_BACKEND=$SHLVL:blesh-${BLE_VERSION-}
+    elif [[ ${bash_preexec_imported-} ]]; then
+        ATUIN_PREEXEC_BACKEND=$SHLVL:bash-preexec
+    elif [[ ${__bp_imported-} ]]; then
+        ATUIN_PREEXEC_BACKEND="$SHLVL:bash-preexec (old)"
+    else
+        ATUIN_PREEXEC_BACKEND=$SHLVL:unknown
+    fi
+}
+
 __atuin_preexec() {
     # Workaround for old versions of bash-preexec
     if [[ ! ${BLE_ATTACHED-} ]]; then
@@ -33,6 +46,10 @@ __atuin_preexec() {
         fi
     fi
 
+    # Note: We update ATUIN_PREEXEC_BACKEND on every preexec because blesh's
+    # attaching state can dynamically change.
+    __atuin_update_preexec_backend
+
     local id
     id=$(atuin history start -- "$1")
     export ATUIN_HISTORY_ID=$id