Keep reconnect health breadcrumbs

Cargo.lock

@@ -436,7 +436,7 @@ dependencies = [
 
 [[package]]
 name = "dosh"
-version = "1.0.0-rc39"
+version = "1.0.0-rc40"
 dependencies = [
  "anyhow",
  "base64",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "dosh"
-version = "1.0.0-rc39"
+version = "1.0.0-rc40"
 edition = "2024"
 license = "MIT"
 

src/bin/dosh-client.rs

@@ -251,6 +251,12 @@ async fn main() -> Result<()> {
         "client.start",
         &[("version", dosh::build_info::VERSION.to_string())],
     );
+    if should_health_log_client_start(args.server.as_deref()) {
+        dosh::trace::health_event(
+            "client.start",
+            &[("version", dosh::build_info::VERSION.to_string())],
+        );
+    }
     let config = load_client_config(None).unwrap_or_default();
     if args.server.as_deref() == Some("cp") {
         return run_cp_command(&config, &args);
@@ -1041,6 +1047,33 @@ fn sanitize_trace_name(value: &str) -> String {
     }
 }
 
+fn should_health_log_client_start(command: Option<&str>) -> bool {
+    !matches!(
+        command,
+        Some(
+            "cp" | "exec"
+                | "ls"
+                | "mkdir"
+                | "rm"
+                | "cat"
+                | "update"
+                | "trace"
+                | "setup"
+                | "selftest"
+                | "proxy-stdio"
+                | "vscode"
+                | "recover"
+                | "repair"
+                | "status"
+                | "sessions"
+                | "restart"
+                | "import-ssh"
+                | "trust"
+                | "doctor"
+        )
+    )
+}
+
 fn run_trace_command(args: &Args) -> Result<()> {
     if args.command.first().is_some_and(|value| value == "report") {
         let config = load_client_config(None).unwrap_or_default();
@@ -1201,10 +1234,15 @@ fn trace_cache_dir() -> PathBuf {
 
 fn newest_client_trace_path() -> Result<Option<PathBuf>> {
     let root = trace_cache_dir();
-    let Ok(entries) = fs::read_dir(&root) else {
-        return Ok(None);
-    };
+    newest_client_trace_path_from(&root, default_health_trace_path())
+}
+
+fn newest_client_trace_path_from(
+    root: &Path,
+    health_path: Option<PathBuf>,
+) -> Result<Option<PathBuf>> {
     let mut newest: Option<(SystemTime, PathBuf)> = None;
+    if let Ok(entries) = fs::read_dir(root) {
         for entry in entries {
             let entry = entry?;
             let path = entry.path();
@@ -1225,14 +1263,35 @@ fn newest_client_trace_path() -> Result<Option<PathBuf>> {
                 .metadata()
                 .and_then(|metadata| metadata.modified())
                 .unwrap_or(SystemTime::UNIX_EPOCH);
+            keep_newer_trace_path(&mut newest, modified, path);
+        }
+    }
+    if let Some(path) = health_path.filter(|path| path.is_file()) {
+        let modified = path
+            .metadata()
+            .and_then(|metadata| metadata.modified())
+            .unwrap_or(SystemTime::UNIX_EPOCH);
+        keep_newer_trace_path(&mut newest, modified, path);
+    }
+    Ok(newest.map(|(_, path)| path))
+}
+
+fn keep_newer_trace_path(
+    newest: &mut Option<(SystemTime, PathBuf)>,
+    modified: SystemTime,
+    path: PathBuf,
+) {
     if newest
         .as_ref()
         .is_none_or(|(old_modified, _)| modified > *old_modified)
     {
-            newest = Some((modified, path));
+        *newest = Some((modified, path));
     }
 }
-    Ok(newest.map(|(_, path)| path))
+
+fn default_health_trace_path() -> Option<PathBuf> {
+    let path = dosh::trace::default_health_log_path();
+    path.is_file().then_some(path)
 }
 
 fn summarize_trace_file(path: &Path, tail: usize) -> Result<TraceReport> {
@@ -7127,6 +7186,14 @@ async fn reconnect(
             ("last_rendered_seq", cred.last_rendered_seq.to_string()),
         ],
     );
+    dosh::trace::health_event(
+        "client.reconnect_start",
+        &[
+            ("session", cred.session.clone()),
+            ("mode", cred.mode.clone()),
+            ("last_rendered_seq", cred.last_rendered_seq.to_string()),
+        ],
+    );
     match try_live_resume(socket, cred, send_seq, size.0, size.1).await {
         Ok((frame, next)) => {
             *cred = next;
@@ -7147,6 +7214,13 @@ async fn reconnect(
                     ("bytes", frame.bytes.len().to_string()),
                 ],
             );
+            dosh::trace::health_event(
+                "client.reconnect_live_ok",
+                &[
+                    ("output_seq", frame.output_seq.to_string()),
+                    ("bytes", frame.bytes.len().to_string()),
+                ],
+            );
             return Ok(Some(frame));
         }
         Err(err) => {
@@ -7154,6 +7228,10 @@ async fn reconnect(
                 "client.reconnect_live_fail",
                 &[("reason", format!("{err:#}"))],
             );
+            dosh::trace::health_event(
+                "client.reconnect_live_fail",
+                &[("reason", format!("{err:#}"))],
+            );
         }
     }
 
@@ -7164,7 +7242,12 @@ async fn reconnect(
                 "client.reconnect_ticket_fail",
                 &[("reason", format!("{err:#}"))],
             );
+            dosh::trace::health_event(
+                "client.reconnect_ticket_fail",
+                &[("reason", format!("{err:#}"))],
+            );
             dosh::trace::event("client.reconnect_none", &[]);
+            dosh::trace::health_event("client.reconnect_none", &[]);
             return Ok(None);
         }
     };
@@ -7187,6 +7270,13 @@ async fn reconnect(
             ("bytes", frame.bytes.len().to_string()),
         ],
     );
+    dosh::trace::health_event(
+        "client.reconnect_ticket_ok",
+        &[
+            ("output_seq", frame.output_seq.to_string()),
+            ("bytes", frame.bytes.len().to_string()),
+        ],
+    );
     Ok(Some(frame))
 }
 
@@ -9325,16 +9415,17 @@ mod tests {
         ensure_tui_safe_status_overlay, expand_ssh_path_tokens, input_contains_focus_in,
         input_matches_escape, is_local_status_target, is_resume_response_for_client,
         latest_release_download_url, load_first_native_identity_with_prompt,
-        native_proxy_udp_warning, parse_dynamic_forward, parse_escape_key, parse_local_forward,
-        parse_remote_forward, parse_ssh_config, parse_trace_line, parse_trace_options,
-        parse_trace_report_options, parse_trace_summary, parse_update_options,
-        post_submit_hold_duration, queue_pending_user_input, queue_stale_pending_user_input,
-        raw_contains_host_table, recv_response_until, refresh_live_addr, release_tag_download_url,
-        release_tag_from_effective_url, release_version_from_tag, render_status_clear,
-        render_status_overlay, requested_env, resolved_startup_command, retire_stream_state,
-        retransmit_stream_opens, rewrite_forward_command, sanitize_trace_name,
-        selected_predict_mode, selected_udp_host, server_version_mismatch,
-        should_flush_terminal_input_after_contact, should_hold_during_startup_gate,
+        native_proxy_udp_warning, newest_client_trace_path_from, parse_dynamic_forward,
+        parse_escape_key, parse_local_forward, parse_remote_forward, parse_ssh_config,
+        parse_trace_line, parse_trace_options, parse_trace_report_options, parse_trace_summary,
+        parse_update_options, post_submit_hold_duration, queue_pending_user_input,
+        queue_stale_pending_user_input, raw_contains_host_table, recv_response_until,
+        refresh_live_addr, release_tag_download_url, release_tag_from_effective_url,
+        release_version_from_tag, render_status_clear, render_status_overlay, requested_env,
+        resolved_startup_command, retire_stream_state, retransmit_stream_opens,
+        rewrite_forward_command, sanitize_trace_name, selected_predict_mode, selected_udp_host,
+        server_version_mismatch, should_flush_terminal_input_after_contact,
+        should_health_log_client_start, should_hold_during_startup_gate,
         should_hold_post_submit_input, should_reconnect_before_input_for_local_sleep,
         should_repaint_idle_terminal, should_strip_unowned_terminal_reports,
         split_after_command_submit, split_trace_tokens, ssh_command_target, ssh_config_uses_proxy,
@@ -10893,6 +10984,40 @@ mod tests {
         }));
     }
 
+    #[test]
+    fn trace_report_falls_back_to_health_log_when_no_client_trace_exists() {
+        let dir = tempfile::tempdir().unwrap();
+        let root = dir.path().join("trace");
+        let health = root.join("health.log");
+        fs::create_dir_all(&root).unwrap();
+        fs::write(
+            &health,
+            concat!(
+                "ts_ms=10 pid=1 event=client.start version=1.0.0\n",
+                "ts_ms=11 pid=1 event=client.reconnect_none\n",
+            ),
+        )
+        .unwrap();
+
+        let selected = newest_client_trace_path_from(&root, Some(health.clone()))
+            .unwrap()
+            .expect("health log fallback");
+        assert_eq!(selected, health);
+        let report = summarize_trace_file(&selected, 10).unwrap();
+        assert_eq!(report.reconnect_none_events, 1);
+    }
+
+    #[test]
+    fn health_log_start_markers_only_for_connect_runs() {
+        assert!(should_health_log_client_start(None));
+        assert!(should_health_log_client_start(Some("palav")));
+        assert!(should_health_log_client_start(Some("forward")));
+        assert!(!should_health_log_client_start(Some("trace")));
+        assert!(!should_health_log_client_start(Some("update")));
+        assert!(!should_health_log_client_start(Some("doctor")));
+        assert!(!should_health_log_client_start(Some("status")));
+    }
+
     #[test]
     fn update_installer_uses_platform_native_script() {
         assert_eq!(

src/trace.rs

@@ -1,11 +1,13 @@
 use std::fs::{File, OpenOptions};
 use std::io::Write;
-use std::path::PathBuf;
+use std::path::{Path, PathBuf};
 use std::sync::{Mutex, OnceLock};
 use std::time::{SystemTime, UNIX_EPOCH};
 
 static TRACE_FILE: OnceLock<Option<Mutex<File>>> = OnceLock::new();
+static HEALTH_FILE: OnceLock<Option<Mutex<File>>> = OnceLock::new();
 static TRACE_BYTES: OnceLock<bool> = OnceLock::new();
+const HEALTH_LOG_MAX_BYTES: u64 = 1024 * 1024;
 
 pub fn enabled() -> bool {
     TRACE_FILE.get_or_init(open_trace_file).is_some()
@@ -19,6 +21,21 @@ pub fn event(name: &str, fields: &[(&str, String)]) {
     let Some(file) = TRACE_FILE.get_or_init(open_trace_file) else {
         return;
     };
+    write_event(file, name, fields);
+}
+
+pub fn health_event(name: &str, fields: &[(&str, String)]) {
+    let Some(file) = HEALTH_FILE.get_or_init(open_health_file) else {
+        return;
+    };
+    write_event(file, name, fields);
+}
+
+pub fn default_health_log_path() -> PathBuf {
+    trace_root().join("health.log")
+}
+
+fn write_event(file: &Mutex<File>, name: &str, fields: &[(&str, String)]) {
     let now = SystemTime::now()
         .duration_since(UNIX_EPOCH)
         .map(|duration| duration.as_millis())
@@ -81,11 +98,49 @@ fn open_trace_file() -> Option<Mutex<File>> {
         .map(Mutex::new)
 }
 
+fn open_health_file() -> Option<Mutex<File>> {
+    let path = health_log_path_from_env()?;
+    rotate_health_log_if_needed(&path);
+    if let Some(parent) = path.parent() {
+        let _ = std::fs::create_dir_all(parent);
+    }
+    OpenOptions::new()
+        .create(true)
+        .append(true)
+        .open(&path)
+        .ok()
+        .map(Mutex::new)
+}
+
+fn health_log_path_from_env() -> Option<PathBuf> {
+    match std::env::var_os("DOSH_HEALTH_LOG") {
+        Some(raw) => {
+            let normalized = raw.to_string_lossy().to_ascii_lowercase();
+            if normalized.is_empty() || matches!(normalized.as_str(), "0" | "false" | "off") {
+                None
+            } else if matches!(normalized.as_str(), "1" | "true" | "on") {
+                Some(default_health_log_path())
+            } else {
+                Some(PathBuf::from(raw))
+            }
+        }
+        None => Some(default_health_log_path()),
+    }
+}
+
+fn rotate_health_log_if_needed(path: &Path) {
+    let Ok(metadata) = std::fs::metadata(path) else {
+        return;
+    };
+    if metadata.len() <= HEALTH_LOG_MAX_BYTES {
+        return;
+    }
+    let rotated = path.with_extension("log.1");
+    let _ = std::fs::remove_file(&rotated);
+    let _ = std::fs::rename(path, rotated);
+}
+
 fn default_trace_path() -> PathBuf {
-    let root = dirs::cache_dir()
-        .unwrap_or_else(std::env::temp_dir)
-        .join("dosh")
-        .join("trace");
     let exe = std::env::current_exe()
         .ok()
         .and_then(|path| {
@@ -93,7 +148,14 @@ fn default_trace_path() -> PathBuf {
                 .map(|stem| stem.to_string_lossy().to_string())
         })
         .unwrap_or_else(|| "dosh".to_string());
-    root.join(format!("{}-{}.log", exe, std::process::id()))
+    trace_root().join(format!("{}-{}.log", exe, std::process::id()))
+}
+
+fn trace_root() -> PathBuf {
+    dirs::cache_dir()
+        .unwrap_or_else(std::env::temp_dir)
+        .join("dosh")
+        .join("trace")
 }
 
 fn truthy_env(name: &str) -> bool {