diff --git a/src/app.rs b/src/app.rs
index 9a701c5..da138c1 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -121,6 +121,23 @@ impl App {
         self.theme.set(theme);
     }
 
+    /// Directory of the event journal (the state directory).
+    pub fn events_dir(&self) -> PathBuf {
+        self.paths
+            .state_file
+            .parent()
+            .map(|p| p.to_path_buf())
+            .unwrap_or_else(|| self.paths.state_file.clone())
+    }
+
+    /// Append an event to the journal; failures are never fatal (logged at
+    /// verbose level only).
+    pub fn emit(&self, event: &crate::events::Event) {
+        if let Err(e) = crate::events::append(&self.events_dir(), event) {
+            self.log.verbose(&format!("cannot write event journal: {e:#}"));
+        }
+    }
+
     /// Ask the user for confirmation on stderr. Accepts y/yes/o/oui.
     pub fn confirm(&self, question: &str) -> Result<bool> {
         if self.cli.yes {
diff --git a/src/commands/doctor_cmd.rs b/src/commands/doctor_cmd.rs
index f50adc7..7afcd06 100644
--- a/src/commands/doctor_cmd.rs
+++ b/src/commands/doctor_cmd.rs
@@ -2,6 +2,7 @@
 
 use super::*;
 use crate::doctor::{self, Status};
+use crate::events::{Event, EventKind};
 use crate::output::{boxed_table, print_json, status_style};
 use crate::runner::SystemRunner;
 use anyhow::Result;
@@ -22,6 +23,12 @@ pub fn run(app: &App, fix: bool) -> Result<i32> {
     // The doctor report probes real tools, even under --dry-run.
     let runner = SystemRunner::new(false, false, &app.log);
     let report = doctor::run(app, &runner);
+    if !app.dry_run() {
+        app.emit(
+            &Event::now(EventKind::Doctor)
+                .with_exit_code(if report.ok() { 0 } else { 1 }),
+        );
+    }
     if app.json() {
         print_json(&report.checks);
         return Ok(if report.ok() { 0 } else { 1 });
diff --git a/src/commands/install_cmd.rs b/src/commands/install_cmd.rs
index 8ac9d23..10e52ee 100644
--- a/src/commands/install_cmd.rs
+++ b/src/commands/install_cmd.rs
@@ -2,6 +2,7 @@
 //! installer, and record the installation in the state database.
 
 use super::*;
+use crate::events::{Event, EventKind};
 use crate::installers;
 use crate::runner::SystemRunner;
 use anyhow::{anyhow, bail, Result};
@@ -137,6 +138,11 @@ pub fn run(app: &App, agent_name: &str, method_sel: Option<&str>, force: bool) -
     let entry = installers::make_entry(agent, method, &outcome, app);
     let version = entry.version.clone().unwrap_or_else(|| "unknown".to_string());
     app.state.set(&entry)?;
+    app.emit(
+        &Event::now(EventKind::Install)
+            .with_agent(agent.name.clone())
+            .with_args(vec![format!("method={}", method.kind)]),
+    );
     app.log.success(&format!(
         "installed {} (v{version}) in {}",
         agent.title(),
diff --git a/src/commands/run_cmd.rs b/src/commands/run_cmd.rs
index 82382dc..cc7ab0c 100644
--- a/src/commands/run_cmd.rs
+++ b/src/commands/run_cmd.rs
@@ -2,6 +2,7 @@
 
 use super::*;
 use crate::cli::StartArgs;
+use crate::events::{self, Event, EventKind};
 use crate::process;
 use anyhow::{bail, Context, Result};
 use std::collections::BTreeMap;
@@ -51,6 +52,15 @@ fn start_one(
                 agent.name
             ));
         }
+        app.emit(
+            &Event::now(EventKind::Start)
+                .with_agent(agent.name.clone())
+                .with_pid(pid)
+                .with_session(crate::repl::session_id())
+                .with_cwd(cwd_string())
+                .with_args(exec.args.clone())
+                .with_env_keys(events::env_keys(&exec.env)),
+        );
         let log = process::agent_log_path(app, &agent.name);
         app.log.success(&format!(
             "{} started (pid {pid}); log: {}",
@@ -70,6 +80,7 @@ fn start_one(
             ));
             return Ok(0);
         }
+        let started = std::time::Instant::now();
         let (prog, prefix) = crate::runner::resolve_program(&exec.program);
         let mut full_args = prefix;
         full_args.extend(exec.args.iter().cloned());
@@ -78,7 +89,17 @@ fn start_one(
             .envs(&exec.env)
             .status()
             .with_context(|| format!("failed to run {}", exec.program))?;
-        Ok(status.code().unwrap_or(1))
+        let code = status.code().unwrap_or(1);
+        app.emit(
+            &Event::now(EventKind::Run)
+                .with_agent(agent.name.clone())
+                .with_cwd(cwd_string())
+                .with_args(exec.args.clone())
+                .with_env_keys(events::env_keys(&exec.env))
+                .with_exit_code(code)
+                .with_duration(started.elapsed().as_secs()),
+        );
+        Ok(code)
     }
 }
 
@@ -123,11 +144,27 @@ fn stop_one(app: &App, agent: &AgentDef, force: bool, timeout: u64) -> Result<i3
             "stale PID {pid} for '{}' (process no longer running); cleaning up",
             agent.name
         ));
+        app.emit(
+            &Event::now(EventKind::Stop)
+                .with_agent(agent.name.clone())
+                .with_pid(pid)
+                .with_reason("stale"),
+        );
         app.state.update_pid(&agent.name, None, None)?;
         return Ok(0);
     }
     app.log.info(&format!("stopping '{}' (pid {pid})", agent.name));
     let stopped = process::stop_pid(pid, force, timeout);
+    let duration = seconds_since(entry.started_at.as_deref());
+    let mut ev = Event::now(EventKind::Stop)
+        .with_agent(agent.name.clone())
+        .with_pid(pid)
+        .with_reason(if force { "force" } else { "signal" })
+        .with_exit_code(if stopped { 0 } else { 1 });
+    if let Some(d) = duration {
+        ev = ev.with_duration(d);
+    }
+    app.emit(&ev);
     app.state.update_pid(&agent.name, None, None)?;
     if stopped {
         app.log.success(&format!("{} stopped", agent.title()));
@@ -175,6 +212,7 @@ pub fn run(app: &App, target: &str, extra: &[OsString]) -> Result<i32> {
         ));
         return Ok(0);
     }
+    let started = std::time::Instant::now();
     let (prog, prefix) = crate::runner::resolve_program(&exec.program);
     let mut full_args = prefix;
     full_args.extend(exec.args.iter().cloned());
@@ -183,5 +221,30 @@ pub fn run(app: &App, target: &str, extra: &[OsString]) -> Result<i32> {
         .envs(&exec.env)
         .status()
         .with_context(|| format!("failed to run {}", exec.program))?;
-    Ok(status.code().unwrap_or(1))
+    let code = status.code().unwrap_or(1);
+    app.emit(
+        &Event::now(EventKind::Run)
+            .with_agent(agent.name.clone())
+            .with_cwd(cwd_string())
+            .with_args(exec.args.clone())
+            .with_env_keys(events::env_keys(&exec.env))
+            .with_exit_code(code)
+            .with_duration(started.elapsed().as_secs()),
+    );
+    Ok(code)
+}
+
+/// Current directory as a string (None when unavailable).
+fn cwd_string() -> Option<String> {
+    std::env::current_dir().ok().map(|p| p.display().to_string())
+}
+
+/// Seconds elapsed since an RFC 3339 timestamp (None when unparsable).
+fn seconds_since(ts: Option<&str>) -> Option<u64> {
+    let t = chrono::DateTime::parse_from_rfc3339(ts?).ok()?;
+    let now = chrono::Utc::now();
+    let secs = now
+        .signed_duration_since(t.with_timezone(&chrono::Utc))
+        .num_seconds();
+    Some(secs.max(0) as u64)
 }
diff --git a/src/commands/uninstall_cmd.rs b/src/commands/uninstall_cmd.rs
index a09e19a..a48ef8f 100644
--- a/src/commands/uninstall_cmd.rs
+++ b/src/commands/uninstall_cmd.rs
@@ -5,6 +5,7 @@
 //! executables found on PATH otherwise.
 
 use super::*;
+use crate::events::{Event, EventKind};
 use anyhow::{Context, Result};
 use std::path::PathBuf;
 use std::process::Command as ProcessCommand;
@@ -57,6 +58,7 @@ pub fn run(app: &App, agent_name: &str, purge: bool) -> Result<i32> {
         remove_from_user_config(app, &agent.name)?;
     }
 
+    app.emit(&Event::now(EventKind::Uninstall).with_agent(agent.name.clone()));
     app.log.success(&format!(
         "uninstalled {} (files removed{})",
         agent.title(),
@@ -178,6 +180,11 @@ fn uninstall_external(app: &App, agent: &AgentDef) -> Result<i32> {
         .and_then(|t| which::which(t).ok())
         .is_none();
     if gone {
+        app.emit(
+            &Event::now(EventKind::Uninstall)
+                .with_agent(agent.name.clone())
+                .with_reason("external"),
+        );
         app.log
             .success(&format!("uninstalled {} (external)", agent.title()));
     } else {
diff --git a/src/commands/update_cmd.rs b/src/commands/update_cmd.rs
index f5fd114..dc6bab2 100644
--- a/src/commands/update_cmd.rs
+++ b/src/commands/update_cmd.rs
@@ -2,6 +2,7 @@
 //! reinstall when an update exists.
 
 use super::*;
+use crate::events::{Event, EventKind};
 use crate::installers;
 use crate::runner::{Runner, SystemRunner};
 use anyhow::{bail, Result};
@@ -96,6 +97,11 @@ fn update_one(app: &App, runner: &dyn Runner, name: &str) -> Result<i32> {
     new_entry.updated_at = Some(installers::now_rfc3339());
     let version = new_entry.version.clone().unwrap_or_else(|| "unknown".to_string());
     app.state.set(&new_entry)?;
+    app.emit(
+        &Event::now(EventKind::Update)
+            .with_agent(agent.name.clone())
+            .with_args(vec![format!("method={}", method.kind)]),
+    );
     app.log.success(&format!(
         "updated {} to v{version}",
         agent.title()
diff --git a/src/events.rs b/src/events.rs
index 51fb2ba..979c4d7 100644
--- a/src/events.rs
+++ b/src/events.rs
@@ -90,8 +90,8 @@ impl Event {
         self
     }
 
-    pub fn with_cwd(mut self, cwd: impl Into<String>) -> Self {
-        self.cwd = Some(cwd.into());
+    pub fn with_cwd(mut self, cwd: Option<String>) -> Self {
+        self.cwd = cwd;
         self
     }
 
@@ -209,6 +209,46 @@ pub fn read_events(dir: &Path, limit: usize) -> Vec<Event> {
     out
 }
 
+/// Append one event as a single JSON line to the journal file for the
+/// event's month (created under `dir`). Returns the file written to.
+/// Retries briefly when the file is locked (Windows).
+pub fn append(dir: &Path, event: &Event) -> anyhow::Result<PathBuf> {
+    let path = dir.join(file_name_for_month(&month_of(&event.ts)));
+    append_to(&path, event)?;
+    Ok(path)
+}
+
+/// Append one event to a specific journal file.
+pub fn append_to(path: &Path, event: &Event) -> anyhow::Result<()> {
+    if let Some(parent) = path.parent() {
+        let _ = std::fs::create_dir_all(parent);
+    }
+    let line = serde_json::to_string(event)?;
+    let mut last_err: Option<std::io::Error> = None;
+    for attempt in 0..5 {
+        match std::fs::OpenOptions::new().create(true).append(true).open(path) {
+            Ok(mut f) => {
+                f.write_all(line.as_bytes())?;
+                f.write_all(b"\n")?;
+                return Ok(());
+            }
+            Err(e) => {
+                last_err = Some(e);
+                if attempt < 4 {
+                    std::thread::sleep(std::time::Duration::from_millis(20 * (attempt + 1)));
+                }
+            }
+        }
+    }
+    Err(anyhow::anyhow!(
+        "cannot append to journal {}: {}",
+        path.display(),
+        last_err
+            .map(|e| e.to_string())
+            .unwrap_or_else(|| "unknown error".to_string())
+    ))
+}
+
 /// Append-only journal living in a directory (the state directory).
 pub struct EventLog {
     dir: PathBuf,
@@ -247,41 +287,11 @@ impl EventLog {
     }
 
     /// Append one event as a single JSON line; returns the file written to.
-    /// Retries briefly when the file is locked (Windows).
     pub fn append(&mut self, event: &Event) -> anyhow::Result<PathBuf> {
         let month = month_of(&event.ts);
         let path = self.file_for(&month);
-        if let Some(parent) = path.parent() {
-            let _ = std::fs::create_dir_all(parent);
-        }
-        let line = serde_json::to_string(event)?;
-        let mut last_err: Option<std::io::Error> = None;
-        for attempt in 0..5 {
-            match std::fs::OpenOptions::new()
-                .create(true)
-                .append(true)
-                .open(&path)
-            {
-                Ok(mut f) => {
-                    f.write_all(line.as_bytes())?;
-                    f.write_all(b"\n")?;
-                    return Ok(path);
-                }
-                Err(e) => {
-                    last_err = Some(e);
-                    if attempt < 4 {
-                        std::thread::sleep(std::time::Duration::from_millis(20 * (attempt + 1)));
-                    }
-                }
-            }
-        }
-        Err(anyhow::anyhow!(
-            "cannot append to journal {}: {}",
-            path.display(),
-            last_err
-                .map(|e| e.to_string())
-                .unwrap_or_else(|| "unknown error".to_string())
-        ))
+        append_to(&path, event)?;
+        Ok(path)
     }
 }
 
diff --git a/src/repl.rs b/src/repl.rs
index e2c4c8a..db81523 100644
--- a/src/repl.rs
+++ b/src/repl.rs
@@ -15,6 +15,7 @@
 use crate::app::App;
 use crate::cli::{Command, StartArgs};
 use crate::commands;
+use crate::events::{Event, EventKind};
 use crate::nav;
 use crate::ps;
 use crate::tables::DataTable;
@@ -884,6 +885,11 @@ pub fn run(app: &App) -> Result<i32> {
     }
     let mut session = ShellSession::start(&app.config);
     let sid = session_id();
+    app.emit(
+        &Event::now(EventKind::Repl)
+            .with_session(sid.clone())
+            .with_cwd(Some(current_dir_string())),
+    );
     print!("{}", banner(app, &session, &sid));
     match run_with_editor(app, &mut session) {
         Ok(code) => Ok(code),
@@ -1379,11 +1385,19 @@ fn eval_pipeline(app: &App, last: &mut Option<DataTable>, line: &str) -> Result<
 /// Run one system command through the active shell (inherited stdio).
 fn run_system(app: &App, session: &ShellSession, line: &str) -> Result<()> {
     app.log.cmd(&format!("{}: {line}", session.current.name));
+    let started = std::time::Instant::now();
     let code = session.run(line)?;
     if code != 0 {
         app.log
             .error(&format!("command exited with code {code}"));
     }
+    app.emit(
+        &Event::now(EventKind::Shell)
+            .with_args(vec![line.to_string()])
+            .with_exit_code(code)
+            .with_duration(started.elapsed().as_secs())
+            .with_cwd(Some(current_dir_string())),
+    );
     Ok(())
 }
 
diff --git a/tests/events_test.rs b/tests/events_test.rs
index 6fb9fc0..567b0c6 100644
--- a/tests/events_test.rs
+++ b/tests/events_test.rs
@@ -29,7 +29,7 @@ fn append_then_read_back_through_read_events() {
     log.append(
         &Event::now(EventKind::Run)
             .with_agent("jcode")
-            .with_cwd("/tmp/demo")
+            .with_cwd(Some("/tmp/demo".to_string()))
             .with_exit_code(0),
     )
     .unwrap();
diff --git a/tests/instrumentation_test.rs b/tests/instrumentation_test.rs
new file mode 100644
index 0000000..9e3add6
--- /dev/null
+++ b/tests/instrumentation_test.rs
@@ -0,0 +1,130 @@
+//! Instrumentation: every real action appends one event to the journal;
+//! dry runs write nothing. Uses the same isolated-App pattern as the other
+//! integration tests (no user config or state leaks in).
+
+mod common;
+
+use agent_manager::app::App;
+use agent_manager::cli::{Cli, StartArgs};
+use agent_manager::commands::run_cmd;
+use agent_manager::events::{self, Event, EventKind};
+use agent_manager::state::InstalledEntry;
+use clap::Parser;
+use std::ffi::OsString;
+use std::path::PathBuf;
+use std::sync::atomic::{AtomicU32, Ordering};
+
+static COUNTER: AtomicU32 = AtomicU32::new(0);
+
+/// Build an isolated App whose catalog contains the given agent definition.
+fn app_with_agent(tag: &str, args: &[&str], agent_yaml: &str) -> App {
+    let id = COUNTER.fetch_add(1, Ordering::SeqCst);
+    let dir = std::env::temp_dir().join(format!("am-instr-{tag}-{}-{id}", std::process::id()));
+    std::fs::create_dir_all(&dir).unwrap();
+    let cfg = common::write_config(&dir, agent_yaml);
+    let mut full = vec!["am".to_string(), "--config".to_string(), cfg.display().to_string()];
+    full.extend(args.iter().map(|s| s.to_string()));
+    let cli = Cli::parse_from(full);
+    let mut app = App::from_cli(cli).expect("app should build");
+    common::isolate(&mut app, &dir);
+    app
+}
+
+fn events(app: &App) -> Vec<Event> {
+    events::read_events(&app.events_dir(), 0)
+}
+
+const ECHO_AGENT: &str = r#"
+agents:
+  - name: echo-agent
+    install: { type: binary, url: "https://example.com/echo.zip" }
+    run: sh
+    args: ["-c", "echo hi"]
+"#;
+
+#[test]
+fn run_emits_one_run_event_with_exit_code() {
+    let app = app_with_agent("run", &["run", "echo-agent"], ECHO_AGENT);
+    let code = run_cmd::run(&app, "echo-agent", &[OsString::from("hello")]).unwrap();
+    assert_eq!(code, 0);
+    let evs = events(&app);
+    assert_eq!(evs.len(), 1, "exactly one event expected, got {:?}", evs);
+    assert_eq!(evs[0].kind, EventKind::Run);
+    assert_eq!(evs[0].agent.as_deref(), Some("echo-agent"));
+    assert_eq!(evs[0].exit_code, Some(0));
+    assert!(evs[0].duration_s.is_some());
+}
+
+#[test]
+fn dry_run_writes_no_event() {
+    let app = app_with_agent("dry", &["run", "echo-agent", "--dry-run"], ECHO_AGENT);
+    let code = run_cmd::run(&app, "echo-agent", &[]).unwrap();
+    assert_eq!(code, 0);
+    assert!(events(&app).is_empty(), "dry-run must not append events");
+    assert!(events::journal_files(&app.events_dir()).is_empty());
+}
+
+fn sleeper_agent() -> String {
+    let (run, args) = if cfg!(windows) {
+        ("ping", r#"["-n", "60", "127.0.0.1"]"#)
+    } else {
+        ("sleep", r#"["60"]"#)
+    };
+    format!(
+        r#"
+agents:
+  - name: sleeper
+    install: {{ type: binary, url: "https://example.com/sleeper.zip" }}
+    run: {run}
+    args: {args}
+"#
+    )
+}
+
+#[test]
+fn start_and_stop_emit_a_matching_pair() {
+    let app = app_with_agent("startstop", &["start", "sleeper", "--background"], &sleeper_agent());
+    // The agent must be "managed" for the PID to be recorded and stoppable.
+    let entry = InstalledEntry {
+        name: "sleeper".to_string(),
+        version: None,
+        method: "binary".to_string(),
+        install_dir: app.paths.install_dir.display().to_string(),
+        bins: vec![],
+        run: "sleeper".to_string(),
+        installed_at: "2026-01-01T00:00:00Z".to_string(),
+        updated_at: None,
+        pid: None,
+        started_at: None,
+    };
+    app.state.set(&entry).unwrap();
+
+    let opts = StartArgs {
+        agent: "sleeper".to_string(),
+        background: true,
+        ..Default::default()
+    };
+    let code = run_cmd::start(&app, &opts).unwrap();
+    assert_eq!(code, 0);
+
+    let stop_code = run_cmd::stop(&app, "sleeper", false, None).unwrap();
+    assert_eq!(stop_code, 0);
+
+    let evs = events(&app);
+    assert_eq!(evs.len(), 2, "expected Start + Stop, got {:?}", evs);
+    assert_eq!(evs[0].kind, EventKind::Start);
+    assert_eq!(evs[0].agent.as_deref(), Some("sleeper"));
+    assert!(evs[0].pid.is_some());
+    assert!(evs[0].session.is_some(), "start events carry a session id");
+    assert_eq!(evs[1].kind, EventKind::Stop);
+    assert_eq!(evs[1].pid, evs[0].pid);
+    assert_eq!(evs[1].exit_code, Some(0));
+    assert!(evs[1].duration_s.is_some(), "stop events carry the duration");
+}
+
+#[test]
+fn fixture_path_is_reachable() {
+    // Guard: the shared fixture used by events_test stays parsable here too.
+    let p = PathBuf::from(env!("CARGO_MANIFEST_DIR")).join("tests/fixtures/events-sample.jsonl");
+    assert_eq!(events::parse_file(&p).len(), 2);
+}