diff --git a/lib/apps/fabro-cli/tests/it/scenario/petri.rs b/lib/apps/fabro-cli/tests/it/scenario/petri.rs
index c641054fa..0662cf70f 100644
--- a/lib/apps/fabro-cli/tests/it/scenario/petri.rs
+++ b/lib/apps/fabro-cli/tests/it/scenario/petri.rs
@@ -27,7 +27,8 @@ use std::process::{Child, Command, Output, Stdio};
 use std::time::{Duration, Instant};
 
 use fabro_client::ServerTarget;
-use fabro_config::{Storage, envfile};
+use fabro_config::daemon::ServerDaemon;
+use fabro_config::{RuntimeDirectory, Storage, envfile};
 use fabro_petri::SqliteRunStore;
 use fabro_petri::checkpoint::CheckpointKey;
 use fabro_petri::engine::{self, RunStatus};
@@ -54,7 +55,6 @@ pub(super) struct RunningServer {
     _storage_root:           tempfile::TempDir,
     pub(super) storage_dir:  PathBuf,
     config_path:             PathBuf,
-    port:                    u16,
     pub(super) api_base_url: String,
     /// The checkpoint gate directory the server forwards to its workers.
     gates_dir:               PathBuf,
@@ -85,7 +85,6 @@ impl RunningServer {
         let home_root = tempfile::tempdir_in("/tmp").expect("home tempdir");
         let storage_root = isolated_storage_dir();
         let storage_dir = storage_root.path().join("storage");
-        let port = reserve_port();
         let config_path = home_root.path().join("settings.toml");
         std::fs::write(
             &config_path,
@@ -117,8 +116,7 @@ impl RunningServer {
             _storage_root: storage_root,
             storage_dir,
             config_path,
-            port,
-            api_base_url: format!("http://127.0.0.1:{port}"),
+            api_base_url: String::new(),
             gates_dir,
             env: env
                 .iter()
@@ -150,16 +148,21 @@ impl RunningServer {
             .arg("--storage-dir")
             .arg(&self.storage_dir)
             .arg("--bind")
-            .arg(format!("127.0.0.1:{}", self.port))
+            .arg("127.0.0.1:0")
             .arg("--config")
             .arg(&self.config_path)
             .stdin(Stdio::null())
             .stdout(self.stderr_log())
             .stderr(self.stderr_log());
-        let mut child = cmd.spawn().expect("the server spawns");
+        // Keep ownership during readiness so a failed launch is killed on Drop.
+        self.child = Some(cmd.spawn().expect("the server spawns"));
         let log_path = self.storage_dir.with_file_name("server.stderr.log");
-        wait_for_http_ready(&self.api_base_url, &mut child, &log_path).await;
-        self.child = Some(child);
+        self.api_base_url = wait_for_http_ready(
+            &Storage::new(&self.storage_dir).runtime_directory(),
+            self.child.as_mut().expect("the server was spawned"),
+            &log_path,
+        )
+        .await;
     }
 
     /// Where the server's stdout and stderr go: a file beside its storage,
@@ -351,38 +354,99 @@ impl Drop for RunningServer {
     }
 }
 
-fn reserve_port() -> u16 {
-    std::net::TcpListener::bind("127.0.0.1:0")
-        .expect("a port binds")
-        .local_addr()
-        .expect("the listener has an address")
-        .port()
-}
-
-async fn wait_for_http_ready(base_url: &str, child: &mut Child, log_path: &Path) {
+async fn wait_for_http_ready(
+    runtime_directory: &RuntimeDirectory,
+    child: &mut Child,
+    log_path: &Path,
+) -> String {
     let client = fabro_test::test_http_client();
     let deadline = Instant::now() + Duration::from_secs(10);
     loop {
-        match client.get(format!("{base_url}/health")).send().await {
-            Ok(response) if response.status().is_success() => return,
-            Ok(_) | Err(_) if Instant::now() < deadline => {
-                if let Some(status) = child.try_wait().expect("the server polls") {
-                    let log = std::fs::read_to_string(log_path).unwrap_or_default();
-                    let tail = log.lines().rev().take(20).collect::<Vec<_>>();
-                    panic!(
-                        "the server exited before it was ready with status {status}; its log ends \
-                         with:\n{}",
-                        tail.into_iter().rev().collect::<Vec<_>>().join("\n")
-                    );
-                }
-                tokio::time::sleep(Duration::from_millis(25)).await;
-            }
-            Ok(response) => panic!("server at {base_url} was not ready: {}", response.status()),
-            Err(err) => panic!("server at {base_url} was not ready: {err}"),
+        if let Some(status) = child.try_wait().expect("the server polls") {
+            let log = std::fs::read_to_string(log_path).unwrap_or_default();
+            let tail = log.lines().rev().take(20).collect::<Vec<_>>();
+            panic!(
+                "the server exited before it was ready with status {status}; its log ends \
+                 with:\n{}",
+                tail.into_iter().rev().collect::<Vec<_>>().join("\n")
+            );
         }
+        // The server binds port zero itself and publishes the actual address.
+        // A SIGKILL leaves the previous record behind: only trust this child.
+        if let Some(daemon) = ServerDaemon::read(runtime_directory)
+            .expect("the server record reads")
+            .filter(|daemon| daemon.pid == child.id())
+        {
+            let base_url = daemon.bind.to_target();
+            match client
+                .get(format!("{base_url}/health"))
+                .timeout(Duration::from_millis(250))
+                .send()
+                .await
+            {
+                Ok(response) if response.status().is_success() => return base_url,
+                Ok(_) | Err(_) => {}
+            }
+        }
+        assert!(
+            Instant::now() < deadline,
+            "the server did not become ready; record: {:?}; log:\n{}",
+            ServerDaemon::read(runtime_directory),
+            std::fs::read_to_string(log_path).unwrap_or_default(),
+        );
+        tokio::time::sleep(Duration::from_millis(25)).await;
     }
 }
 
+/// A crashed server's port may already belong to a healthy unrelated
+/// service. Relaunch must discover the new child, not trust the stale record.
+#[tokio::test(flavor = "multi_thread")]
+async fn a_server_relaunch_uses_its_own_port_when_the_old_port_is_occupied() {
+    let _context = test_context!();
+    let mut server = RunningServer::start().await;
+    let old_url = server.api_base_url.clone();
+    server.kill();
+
+    let listener = tokio::net::TcpListener::bind(
+        old_url
+            .strip_prefix("http://")
+            .expect("the server uses HTTP"),
+    )
+    .await
+    .expect("the crashed server's port is occupied");
+    let impostor = tokio::spawn(async move {
+        axum::serve(
+            listener,
+            axum::Router::new().route("/health", axum::routing::get(|| async { "ok" })),
+        )
+        .await
+        .expect("the unrelated health server serves");
+    });
+    let _impostor_guard = scopeguard::guard(impostor, |task| task.abort());
+    fabro_test::expect_reqwest_status(
+        fabro_test::test_http_client()
+            .get(format!("{old_url}/health"))
+            .send()
+            .await
+            .expect("the unrelated health server responds"),
+        axum::http::StatusCode::OK,
+        "GET /health on the occupied old port",
+    )
+    .await;
+
+    server.launch().await;
+    assert_ne!(server.api_base_url, old_url);
+    let daemon = ServerDaemon::read(&Storage::new(&server.storage_dir).runtime_directory())
+        .expect("the server record reads")
+        .expect("the new server wrote its record");
+    assert_eq!(
+        daemon.pid,
+        server.child.as_ref().expect("the new server runs").id()
+    );
+    assert_eq!(daemon.bind.to_target(), server.api_base_url);
+    server.shutdown();
+}
+
 /// A workspace holding a command-only bundle whose `workflow.toml` names
 /// Petri, with the given stage script.
 fn write_petri_workspace(context: &fabro_test::TestContext, script: &str) -> PathBuf {