CLAUDE.md

@@ -313,7 +313,13 @@ docker exec stdout → tokio task → emit("terminal-output-{sessionId}") → li
     approach converges on the worst state: a 400 MB browser present with its libraries gone.
   - The layer sits immediately after Node (npx is its only prerequisite) and well above the shim
     `COPY`s, so editing a shim does not re-run a multi-hundred-megabyte apt install.
-- **`entrypoint.sh`** — UID/GID remapping to match host user, SSH key setup (`sync_host_ssh` *merges* the host dir into `~/.ssh`; never wipe it — container-made keys live there on the home volume), git config, docker socket permissions, Claude Code settings.json injection, then `sleep infinity`
+- **`entrypoint.sh`** — UID/GID remapping to match host user, SSH key setup (`sync_host_ssh` *merges* the host dir into `~/.ssh`; never wipe it — container-made keys live there on the home volume), git config, docker socket permissions, Claude Code settings.json injection, then stays resident **as root** waiting on a root-owned
+  `triple-c-keepalive` sleep (respawned if killed; SIGTERM trap so `docker stop` is immediate).
+  **Never hand the container's lifetime to a process the `claude` user owns** — it used to end in
+  `exec su … claude -c "exec sleep infinity"`, and any `pkill sleep` / `kill -9 -1` a Claude
+  session ran killed the whole container. `container_watch.rs` (one Docker `die`-event
+  subscription) is what flips a project whose container exits on its own to Stopped and emits
+  `project-container-exited` with a `reason` (`exited` toasts; `found_stopped`, the first look of a run, is silent); `useProjectStatusEvents` applies it
 - **`triple-c-scheduler`** — Bash-based scheduled task system for recurring Claude Code invocations
 
 **`/home/claude` in the image is seed-only.** It is the mount point of the named volume
@@ -672,8 +678,9 @@ Anthropic and Bedrock deliberately keep Claude Code's own defaults.
   now", the host builds the project's effective set (`global − disabled ∪ project`), then uploads
   `payload.tar` **and the app-embedded script `src/marketplace/sync.sh`** (`include_str!`, not a
   file in `container/`) to `~/.claude/triple-c/marketplace/incoming/` and runs it as `claude`,
-  once the entrypoint has finished (`pgrep -x -f 'su -s /bin/bash claude -c exec sleep
-  infinity'`). The script is re-uploaded on every sync rather than baked into the image, so every
+  once the entrypoint has finished (`READY_PROBE`: a root `triple-c-keepalive infinity` process
+  on current images, `su -s /bin/bash claude -c exec sleep infinity` on older ones — keep both).
+  The script is re-uploaded on every sync rather than baked into the image, so every
   existing project always gets the version that matches the running app — `container/` is never
   touched for this feature. The script only removes files and hook entries it recorded in
   `~/.claude/triple-c/marketplace/state.json`; it must never overwrite or delete user-created

TECHNICAL.md

@@ -137,7 +137,7 @@ Implementation gotchas for the terminal view and its global controls (merged in
 │                                                          │
 │  User: claude (UID/GID remapped to match host)           │
 │  Entrypoint: UID/GID remap → SSH setup → git config →   │
-│              docker socket perms → sleep infinity        │
+│              docker socket perms → root keepalive wait   │
 └──────────────────────────────────────────────────────────┘
 ```
 
@@ -164,7 +164,7 @@ Terminal resize follows the same pattern: `ResizeObserver` detects container siz
 
 Containers follow a **stop/start** model, not create/destroy:
 
-1. **First start**: A new container is created with bind mounts, named volumes, environment variables, and labels. The entrypoint remaps UID/GID, configures SSH and git, rebuilds the scheduler crontab, then runs `sleep infinity` to keep the container alive.
+1. **First start**: A new container is created with bind mounts, named volumes, environment variables, and labels. The entrypoint remaps UID/GID, configures SSH and git, rebuilds the scheduler crontab, then stays resident as root waiting on a root-owned `triple-c-keepalive` sleep — never a process the `claude` user can kill, since any `pkill sleep` a Claude session runs would otherwise stop the container.
 2. **Terminal open**: `docker exec` launches `claude` with a PTY in the running container, with the permission-mode flags from `PermissionMode::cli_args()` (or `bash -l` for a shell session).
 3. **Stop**: `docker stop` halts the container but preserves its filesystem. Any packages Claude installed via `apt`, `pip`, `cargo`, etc. survive.
 4. **Restart**: `docker start` resumes the existing container — unless `container_needs_recreation()` finds a `triple-c.*` label that no longer matches the project's settings, in which case the container is committed to a snapshot image (`triple-c-snapshot-{projectId}:latest`), removed, and recreated from that snapshot. Installed tools survive; the named volumes are untouched.
@@ -348,7 +348,7 @@ The entrypoint solves this by:
 3. Relocating any existing system user/group that conflicts with the target UID/GID.
 4. Fixing ownership of `/home/claude` after the change.
 
-This runs as root in the entrypoint, then the final `exec su -s /bin/bash claude -c "exec sleep infinity"` drops to the remapped user.
+This runs as root in the entrypoint. The entrypoint itself then stays running as root to keep the container alive; sessions reach the remapped `claude` user through `docker exec --user`. (Older images ended in `exec su -s /bin/bash claude -c "exec sleep infinity"`, which let any `claude` process stop the container by killing that sleep.)
 
 ### SSH Key Handling
 

app/src-tauri/src/container_watch.rs

@@ -0,0 +1,396 @@
+//! Notices a project container that stopped without the app asking.
+//!
+//! Until this existed the app only ever learned a container's state from its
+//! own commands and from `reconcile_project_statuses`, which the frontend runs
+//! once, when Docker first answers. A container that died underneath a running
+//! app — the entrypoint's keepalive killed, an OOM, `docker stop` from a shell,
+//! a daemon restart — left its project at Running indefinitely: every terminal
+//! disconnected, while the sidebar, Start/Stop and Project Home all still
+//! described a live container.
+//!
+//! One subscription to Docker's event stream, filtered daemon-side to container
+//! `die` events, so an idle daemon costs nothing and the app hears about a death
+//! as it happens. No polling loop. Each `die` naming a project's container is
+//! confirmed with one inspect before anything changes (an event can be
+//! replayed, and a restart can reuse the id), and the flip itself is
+//! [`ProjectsStore::mark_exited`]'s compare-and-set, which never touches a
+//! project a command owns and refuses if the store changed while the inspect
+//! was in flight. The frontend hears it on [`CONTAINER_EXITED_EVENT`].
+//!
+//! The stream drops whenever the daemon does. Each (re)subscription asks for
+//! events since just before it, and first re-checks every Running project once —
+//! the only window that replay cannot cover is a daemon restart, which forgets
+//! its event history, and that is exactly when containers go away.
+
+use std::collections::HashMap;
+use std::future::Future;
+use std::sync::Arc;
+use std::time::{Duration, Instant};
+
+use bollard::errors::Error as DockerError;
+use bollard::models::{EventMessage, EventMessageTypeEnum};
+use bollard::system::EventsOptions;
+use bollard::Docker;
+use futures_util::StreamExt;
+use serde::Serialize;
+use tauri::{AppHandle, Emitter};
+use tokio::sync::watch;
+
+use crate::models::{Project, ProjectStatus};
+use crate::storage::projects_store::{ExitMark, ProjectsStore};
+
+/// Emitted as a [`ContainerExited`] whenever this module flips a project to
+/// Stopped.
+pub const CONTAINER_EXITED_EVENT: &str = "project-container-exited";
+
+const RETRY_MIN: Duration = Duration::from_secs(5);
+const RETRY_MAX: Duration = Duration::from_secs(60);
+/// A stream that stayed up this long (or delivered anything) was a working
+/// connection, so its loss starts the backoff over. Anything shorter — the
+/// daemon answers ping but the events call fails — keeps backing off, or it
+/// would re-sweep and re-log every five seconds forever.
+const STABLE_AFTER: Duration = Duration::from_secs(60);
+/// How often `settle` re-confirms when the store keeps changing under it.
+const SETTLE_ATTEMPTS: usize = 3;
+
+/// How the app found out, which decides whether it is news to the user.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize)]
+#[serde(rename_all = "snake_case")]
+pub enum ExitReason {
+    /// The container died while this app was running and watching — any
+    /// sessions it had were just cut off.
+    Exited,
+    /// Found already stopped on the first look of this run: it went down
+    /// while the app was closed (a host reboot, typically). Nothing the user
+    /// can see was interrupted, so it is not news.
+    FoundStopped,
+}
+
+#[derive(Debug, Clone, Serialize)]
+pub struct ContainerExited<'a> {
+    pub project: &'a Project,
+    pub reason: ExitReason,
+}
+
+/// The container id a Docker event reports as having died, if it is one.
+pub(crate) fn died_container(msg: &EventMessage) -> Option<&str> {
+    if msg.typ != Some(EventMessageTypeEnum::CONTAINER) || msg.action.as_deref() != Some("die") {
+        return None;
+    }
+    msg.actor.as_ref()?.id.as_deref().filter(|id| !id.is_empty())
+}
+
+/// `true` only when Docker positively says the container is not running: it
+/// inspects as stopped, or it no longer exists. Any other failure is "don't
+/// know" — `docker::is_container_running` maps every error to `false`, which
+/// is right for its callers and wrong here, where it would mark every project
+/// Stopped the moment the daemon hiccups.
+async fn has_exited(docker: &Docker, container_id: &str) -> bool {
+    match docker.inspect_container(container_id, None).await {
+        Ok(info) => !info.state.and_then(|s| s.running).unwrap_or(false),
+        Err(DockerError::DockerResponseServerError { status_code: 404, .. }) => true,
+        Err(_) => false,
+    }
+}
+
+fn project_busy(project_id: &str) -> bool {
+    crate::project_lock::held(project_id).is_some()
+}
+
+/// Confirm `container_id` really stopped and, if a project was Running on it,
+/// flip that project. Returns what changed.
+async fn settle(docker: &Docker, store: &ProjectsStore, container_id: &str) -> Option<Project> {
+    for _ in 0..SETTLE_ATTEMPTS {
+        // Cheap and allocation-free: most containers that die are not ours
+        // (probe and scratch containers, other software on the daemon), and
+        // those cost no inspect at all.
+        let seen = store.running_on(container_id)?;
+        if !has_exited(docker, container_id).await {
+            return None;
+        }
+        match store.mark_exited(container_id, &seen, project_busy) {
+            ExitMark::Flipped(p) => return Some(*p),
+            ExitMark::NotApplicable => return None,
+            // The store moved while Docker was answering — possibly a stop and
+            // start of this very container. The inspect is stale; ask again.
+            ExitMark::Changed => continue,
+        }
+    }
+    None
+}
+
+/// Re-check every Running project once. Used on each (re)subscription.
+async fn sweep(docker: &Docker, store: &ProjectsStore) -> Vec<Project> {
+    let mut changed = Vec::new();
+    for p in store.list() {
+        if p.status != ProjectStatus::Running {
+            continue;
+        }
+        let Some(cid) = p.container_id.as_deref() else { continue };
+        if let Some(c) = settle(docker, store, cid).await {
+            changed.push(c);
+        }
+    }
+    changed
+}
+
+fn die_filter() -> HashMap<String, Vec<String>> {
+    HashMap::from([
+        ("type".to_string(), vec!["container".to_string()]),
+        ("event".to_string(), vec!["die".to_string()]),
+    ])
+}
+
+/// The wait before connection attempt `n + 1`, after `n` consecutive
+/// unproductive ones: 5 s, 10 s, 20 s, 40 s, then 60 s for good.
+fn retry_delay(consecutive_failures: u32) -> Duration {
+    let doublings = consecutive_failures.saturating_sub(1).min(8);
+    (RETRY_MIN * 2u32.pow(doublings)).min(RETRY_MAX)
+}
+
+/// `fut`, unless the app starts shutting down first. Every Docker call in here
+/// goes through this: a wedged daemon must not hold shutdown for its full
+/// budget.
+async fn unless_cancelled<T>(
+    cancel: &mut watch::Receiver<bool>,
+    fut: impl Future<Output = T>,
+) -> Option<T> {
+    if *cancel.borrow() {
+        return None;
+    }
+    tokio::select! {
+        // `Err` means the sender is gone, i.e. so is the app.
+        _ = cancel.changed() => None,
+        v = fut => Some(v),
+    }
+}
+
+/// One connection: ping, sweep, then follow the event stream until it ends.
+/// `None` when cancelled; otherwise whether the connection was a working one
+/// (see [`STABLE_AFTER`]).
+async fn watch_once(
+    store: &ProjectsStore,
+    cancel: &mut watch::Receiver<bool>,
+    sweep_reason: ExitReason,
+    on_change: &impl Fn(&Project, ExitReason),
+) -> Option<bool> {
+    let Ok(docker) = crate::docker::get_docker() else { return Some(false) };
+    if unless_cancelled(cancel, docker.ping()).await?.is_err() {
+        return Some(false);
+    }
+    // A second's overlap: the daemon replays from `since`, so a death during
+    // the sweep below is still delivered. Duplicates are harmless — `settle`
+    // confirms with an inspect every time.
+    let since = (chrono::Utc::now().timestamp() - 1).to_string();
+    for p in unless_cancelled(cancel, sweep(&docker, store)).await? {
+        on_change(&p, sweep_reason);
+    }
+    let mut events = docker.events(Some(EventsOptions::<String> {
+        since: Some(since),
+        until: None,
+        filters: die_filter(),
+    }));
+    let connected = Instant::now();
+    let mut delivered = false;
+    loop {
+        match unless_cancelled(cancel, events.next()).await? {
+            Some(Ok(msg)) => {
+                delivered = true;
+                if let Some(cid) = died_container(&msg) {
+                    if let Some(p) = unless_cancelled(cancel, settle(&docker, store, cid)).await? {
+                        on_change(&p, ExitReason::Exited);
+                    }
+                }
+            }
+            Some(Err(e)) => {
+                log::info!("Container watch: event stream ended ({e}) — reconnecting");
+                break;
+            }
+            None => {
+                log::info!("Container watch: event stream closed — reconnecting");
+                break;
+            }
+        }
+    }
+    Some(delivered || connected.elapsed() >= STABLE_AFTER)
+}
+
+/// Watch until `cancel` flips, calling `on_change` for every project whose
+/// container is found to have stopped on its own. Separate from [`spawn`] so a
+/// test can drive it without a Tauri app.
+pub(crate) async fn run(
+    store: Arc<ProjectsStore>,
+    mut cancel: watch::Receiver<bool>,
+    on_change: impl Fn(&Project, ExitReason),
+) {
+    // Only the first look of the run finds containers that stopped while the
+    // app was closed. A sweep after a reconnect finds ones that died while we
+    // were running — the daemon restarting is the usual cause — and those
+    // cut off live sessions just as a `die` event would.
+    let mut sweep_reason = ExitReason::FoundStopped;
+    let mut failures: u32 = 0;
+    loop {
+        let Some(healthy) = watch_once(&store, &mut cancel, sweep_reason, &on_change).await else {
+            return;
+        };
+        sweep_reason = ExitReason::Exited;
+        failures = if healthy { 1 } else { failures + 1 };
+        unless_cancelled(&mut cancel, tokio::time::sleep(retry_delay(failures))).await;
+        if *cancel.borrow() {
+            return;
+        }
+    }
+}
+
+/// Start the watcher for the life of the app.
+pub fn spawn(
+    app: AppHandle,
+    store: Arc<ProjectsStore>,
+    cancel: watch::Receiver<bool>,
+) -> tauri::async_runtime::JoinHandle<()> {
+    tauri::async_runtime::spawn(async move {
+        run(store, cancel, |p, reason| {
+            log::warn!(
+                "Project '{}' ({}): its container stopped without the app asking ({:?}) — marking Stopped",
+                p.name,
+                p.id,
+                reason
+            );
+            let _ = app.emit(CONTAINER_EXITED_EVENT, ContainerExited { project: p, reason });
+        })
+        .await;
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use bollard::models::EventActor;
+
+    fn event(typ: EventMessageTypeEnum, action: &str, id: Option<&str>) -> EventMessage {
+        EventMessage {
+            typ: Some(typ),
+            action: Some(action.to_string()),
+            actor: Some(EventActor { id: id.map(str::to_string), attributes: None }),
+            ..Default::default()
+        }
+    }
+
+    #[test]
+    fn only_a_container_die_names_a_container() {
+        let die = event(EventMessageTypeEnum::CONTAINER, "die", Some("abc"));
+        assert_eq!(died_container(&die), Some("abc"));
+
+        for (typ, action, id) in [
+            (EventMessageTypeEnum::CONTAINER, "stop", Some("abc")),
+            (EventMessageTypeEnum::CONTAINER, "start", Some("abc")),
+            (EventMessageTypeEnum::CONTAINER, "exec_die", Some("abc")),
+            (EventMessageTypeEnum::NETWORK, "die", Some("abc")),
+            (EventMessageTypeEnum::CONTAINER, "die", None),
+            (EventMessageTypeEnum::CONTAINER, "die", Some("")),
+        ] {
+            assert_eq!(died_container(&event(typ, action, id)), None, "{typ:?} {action} {id:?}");
+        }
+    }
+
+    #[test]
+    fn the_subscription_is_filtered_to_container_deaths_daemon_side() {
+        let f = die_filter();
+        assert_eq!(f.get("type"), Some(&vec!["container".to_string()]));
+        assert_eq!(f.get("event"), Some(&vec!["die".to_string()]));
+        assert_eq!(f.len(), 2);
+    }
+
+    #[test]
+    fn retries_back_off_to_a_minute_and_stay_there() {
+        let secs: Vec<u64> = (1..=7).map(|n| retry_delay(n).as_secs()).collect();
+        assert_eq!(secs, vec![5, 10, 20, 40, 60, 60, 60]);
+        assert_eq!(retry_delay(0), RETRY_MIN);
+        assert_eq!(retry_delay(u32::MAX), RETRY_MAX);
+    }
+
+    #[test]
+    fn the_event_says_why_so_the_ui_can_tell_news_from_housekeeping() {
+        let p = Project::new("demo".to_string(), Vec::new());
+        let v = serde_json::to_value(ContainerExited { project: &p, reason: ExitReason::Exited }).unwrap();
+        assert_eq!(v["reason"], "exited");
+        assert_eq!(v["project"]["name"], "demo");
+        let v = serde_json::to_value(ContainerExited { project: &p, reason: ExitReason::FoundStopped })
+            .unwrap();
+        assert_eq!(v["reason"], "found_stopped");
+        assert_eq!(CONTAINER_EXITED_EVENT, "project-container-exited");
+    }
+
+    /// The shutdown path: a Docker call that never answers (a wedged daemon)
+    /// must give way to cancellation at once, not hold teardown.
+    #[tokio::test]
+    async fn a_hung_docker_call_yields_to_cancellation() {
+        let (tx, mut rx) = watch::channel(false);
+        let canceller = tokio::spawn(async move {
+            tokio::time::sleep(Duration::from_millis(20)).await;
+            let _ = tx.send(true);
+        });
+        let hung = std::future::pending::<()>();
+        let out = tokio::time::timeout(Duration::from_secs(2), unless_cancelled(&mut rx, hung)).await;
+        assert_eq!(out.expect("returned promptly"), None);
+        canceller.await.unwrap();
+        // Already cancelled: it does not even start the call.
+        assert_eq!(unless_cancelled(&mut rx, async { 1 }).await, None);
+    }
+
+    /// End to end against a real daemon: a Running project whose container is
+    /// killed from outside the app is flipped to Stopped and reported as a live
+    /// exit; one found already stopped on the first look is reported as such;
+    /// and one whose container is still up is left alone.
+    #[tokio::test]
+    #[ignore = "needs a Docker daemon; creates and removes throwaway containers"]
+    async fn a_container_killed_outside_the_app_flips_its_project_to_stopped() {
+        use std::process::Command;
+        fn docker_cli(args: &[&str]) -> String {
+            let out = Command::new("docker").args(args).output().expect("docker cli");
+            assert!(out.status.success(), "docker {:?}: {}", args, String::from_utf8_lossy(&out.stderr));
+            String::from_utf8_lossy(&out.stdout).trim().to_string()
+        }
+        let tag = uuid::Uuid::new_v4().simple().to_string();
+        let doomed = docker_cli(&["run", "-d", "--name", &format!("tc-watch-a-{tag}"), "alpine:3", "sleep", "300"]);
+        let alive = docker_cli(&["run", "-d", "--name", &format!("tc-watch-b-{tag}"), "alpine:3", "sleep", "300"]);
+        let already = docker_cli(&["create", "--name", &format!("tc-watch-c-{tag}"), "alpine:3", "true"]);
+
+        let dir = std::env::temp_dir().join(format!("triple-c-watch-{tag}"));
+        std::fs::create_dir_all(&dir).unwrap();
+        let running = |name: &str, cid: &str| {
+            let mut p = Project::new(name.to_string(), Vec::new());
+            p.container_id = Some(cid.to_string());
+            p.status = ProjectStatus::Running;
+            p
+        };
+        let (a, b, c) = (running("a", &doomed), running("b", &alive), running("c", &already));
+        let (a_id, b_id, c_id) = (a.id.clone(), b.id.clone(), c.id.clone());
+        let store = Arc::new(ProjectsStore::over_file_for_test(dir.join("projects.json"), vec![a, b, c]));
+
+        let (cancel_tx, cancel_rx) = watch::channel(false);
+        let (seen_tx, mut seen_rx) = tokio::sync::mpsc::unbounded_channel::<(String, ExitReason)>();
+        let watcher = tokio::spawn(run(store.clone(), cancel_rx, move |p, why| {
+            let _ = seen_tx.send((p.id.clone(), why));
+        }));
+        let first = tokio::time::timeout(Duration::from_secs(10), seen_rx.recv()).await;
+        // Subscribed by now (the sweep precedes it, and `since` overlaps);
+        // kill from "outside".
+        docker_cli(&["kill", &doomed]);
+        let second = tokio::time::timeout(Duration::from_secs(15), seen_rx.recv()).await;
+
+        let t0 = Instant::now();
+        let _ = cancel_tx.send(true);
+        let _ = watcher.await;
+        let shutdown = t0.elapsed();
+        let statuses: Vec<ProjectStatus> =
+            [&a_id, &b_id, &c_id].iter().map(|id| store.get(id).unwrap().status).collect();
+        docker_cli(&["rm", "-f", &doomed, &alive, &already]);
+        std::fs::remove_dir_all(&dir).ok();
+
+        assert_eq!(first.expect("sweep within 10s"), Some((c_id, ExitReason::FoundStopped)));
+        assert_eq!(second.expect("die within 15s"), Some((a_id, ExitReason::Exited)));
+        assert_eq!(statuses, vec![ProjectStatus::Stopped, ProjectStatus::Running, ProjectStatus::Stopped]);
+        assert!(shutdown < Duration::from_secs(1), "stopped watching in {shutdown:?}");
+    }
+}

app/src-tauri/src/lib.rs

@@ -3,6 +3,7 @@ mod browser_view;
 #[cfg(test)]
 mod command_census;
 mod commands;
+mod container_watch;
 mod docker;
 pub mod file_viewer;
 mod install_helper;
@@ -307,6 +308,16 @@ pub fn run() {
                 .await;
             });
 
+            // Notice a project container that stops without the app asking
+            // (its keepalive killed, an OOM, a `docker stop` from a shell) and
+            // flip the project to Stopped. One daemon-side-filtered event
+            // subscription for the app's lifetime — see `container_watch`.
+            lifecycle_setup.track(container_watch::spawn(
+                app.handle().clone(),
+                projects_store_setup.clone(),
+                lifecycle_setup.cancellation(),
+            ));
+
             // Marketplaces: refresh each once at startup, in the background.
             // Failures are logged, not toasted — the Marketplace tab shows them.
             {

app/src-tauri/src/marketplace/sync.rs

@@ -14,10 +14,19 @@ pub const INCOMING_DIR: &str = "/home/claude/.claude/triple-c/marketplace/incomi
 /// app version reaches existing containers without an image migration.
 pub const SYNC_SCRIPT: &str = include_str!("sync.sh");
 
-/// True once the entrypoint has finished: its last step execs this exact
-/// command line. Before that it may still be merging `settings.json` or running
-/// `claude update`, both of which the sync would race.
-const READY_PROBE: &str = "pgrep -x -f 'su -s /bin/bash claude -c exec sleep infinity' >/dev/null";
+/// True once the entrypoint has finished: its last step starts a process with
+/// one of these exact command lines. Before that it may still be merging
+/// `settings.json` or running `claude update`, both of which the sync would race.
+///
+/// Two, because there are two generations of entrypoint in the field. Current
+/// images keep the container alive with a root-owned `triple-c-keepalive`
+/// sleep (so a `pkill sleep` run as `claude` cannot stop the container — see
+/// the end of `container/entrypoint.sh`); older ones `exec su … claude -c exec
+/// sleep infinity`, and a project keeps its base image until it is migrated.
+/// Both are matched as root-owned only (the old image's `su` runs as root), so
+/// a `claude` process wearing either command line cannot fake readiness.
+const READY_PROBE: &str = "pgrep -u root -x -f 'triple-c-keepalive infinity' >/dev/null \
+                           || pgrep -u root -x -f 'su -s /bin/bash claude -c exec sleep infinity' >/dev/null";
 const READY_TIMEOUT: Duration = Duration::from_secs(180);
 const READY_POLL: Duration = Duration::from_secs(2);
 
@@ -196,14 +205,22 @@ mod tests {
 
     #[test]
     fn readiness_probes_the_entrypoints_final_exec() {
+        // Both generations of entrypoint: a project keeps the base image it
+        // was built from until it migrates, so the old `su … sleep` ending is
+        // the common case for years and must still read as ready.
         assert_eq!(
             ready_probe_cmd(),
             vec![
                 "sh",
                 "-c",
-                "pgrep -x -f 'su -s /bin/bash claude -c exec sleep infinity' >/dev/null"
+                "pgrep -u root -x -f 'triple-c-keepalive infinity' >/dev/null \
+                 || pgrep -u root -x -f 'su -s /bin/bash claude -c exec sleep infinity' >/dev/null"
             ]
         );
+        // The marker name is shared with the entrypoint; a rename on one side
+        // only would leave every new container "not ready" for 180 s.
+        let entrypoint = include_str!("../../../../container/entrypoint.sh");
+        assert!(entrypoint.contains("exec -a triple-c-keepalive sleep infinity"));
         assert_eq!(READY_POLL, Duration::from_secs(2));
         assert_eq!(READY_TIMEOUT, Duration::from_secs(180));
     }

app/src-tauri/src/storage/projects_store.rs

@@ -1,10 +1,42 @@
 use std::fs;
 use std::path::{Path, PathBuf};
+use std::sync::atomic::{AtomicU64, Ordering};
 use std::sync::Mutex;
 
 use crate::models::marketplace::{MarketplaceInstall, MarketplaceItemRef};
 use crate::models::Project;
 
+/// Proof that, at some revision of the store, a project was `Running` on a
+/// given container. See [`ProjectsStore::running_on`].
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct RunningSighting {
+    revision: u64,
+}
+
+/// What [`ProjectsStore::mark_exited`] did.
+#[derive(Debug)]
+pub enum ExitMark {
+    /// Flipped to `Stopped`; the updated record.
+    Flipped(Box<Project>),
+    /// The store changed since the sighting while a project is still Running
+    /// on that container — the caller's Docker check may be stale. Re-check.
+    Changed,
+    /// No project is Running on that container, or a command owns it.
+    NotApplicable,
+}
+
+/// The one rule for "this project is Running on that container". Both ids
+/// must be at least a short id long: a blank or truncated value is a prefix
+/// of everything and would match every container on the daemon.
+fn is_running_on(p: &Project, container_id: &str) -> bool {
+    p.status == crate::models::ProjectStatus::Running
+        && container_id.len() >= 12
+        && p.container_id
+            .as_deref()
+            .filter(|stored| stored.len() >= 12)
+            .is_some_and(|stored| stored.starts_with(container_id) || container_id.starts_with(stored))
+}
+
 /// The sticky marker for `projects.json`: `projects.json.corrupt`, beside it.
 ///
 /// Derived from the file rather than from `dirs::data_dir()` so the marker
@@ -64,6 +96,8 @@ fn record_corrupt_load(file_path: &Path, now: &chrono::DateTime<chrono::Utc>) {
 pub struct ProjectsStore {
     projects: Mutex<Vec<Project>>,
     file_path: PathBuf,
+    /// Bumped by every `save()`; see [`ProjectsStore::mark_exited`].
+    revision: AtomicU64,
 }
 
 impl ProjectsStore {
@@ -147,6 +181,7 @@ impl ProjectsStore {
         let store = Self {
             projects: Mutex::new(projects),
             file_path,
+            revision: AtomicU64::new(0),
         };
 
         // Persist migrated/reconciled format back to disk
@@ -161,11 +196,21 @@ impl ProjectsStore {
         Ok(store)
     }
 
+    /// A store over a file the test owns (`new()` insists on the real data dir).
+    #[cfg(test)]
+    pub(crate) fn over_file_for_test(file_path: PathBuf, projects: Vec<Project>) -> Self {
+        Self { projects: Mutex::new(projects), file_path, revision: AtomicU64::new(0) }
+    }
+
     fn lock(&self) -> std::sync::MutexGuard<'_, Vec<Project>> {
         self.projects.lock().unwrap_or_else(|e| e.into_inner())
     }
 
     fn save(&self, projects: &[Project]) -> Result<(), String> {
+        // Every mutation saves with the lock held, so this counts every change
+        // to the in-memory list — bumped first, because a failed write has
+        // still changed what the list holds.
+        self.revision.fetch_add(1, Ordering::SeqCst);
         let data = serde_json::to_string_pretty(projects)
             .map_err(|e| format!("Failed to serialize projects: {}", e))?;
 
@@ -237,6 +282,69 @@ impl ProjectsStore {
         Ok(())
     }
 
+    /// Is some project `Running` on `container_id`? Checked under the lock
+    /// without cloning anything — the container watcher asks this for every
+    /// container death on the daemon, nearly all of them not ours.
+    ///
+    /// The answer carries the store's revision, which [`Self::mark_exited`]
+    /// needs: the caller confirms with Docker that the container really is
+    /// down *between* the two calls, and that inspect can be slow.
+    pub fn running_on(&self, container_id: &str) -> Option<RunningSighting> {
+        let projects = self.lock();
+        projects
+            .iter()
+            .any(|p| is_running_on(p, container_id))
+            .then(|| RunningSighting { revision: self.revision.load(Ordering::SeqCst) })
+    }
+
+    /// A container stopped without the app asking: flip the project that is
+    /// `Running` on it to `Stopped`.
+    ///
+    /// A compare-and-set under the store lock rather than a read followed by
+    /// `update_status`, and against two things:
+    ///
+    /// * **The store's revision as of `seen`.** Between [`Self::running_on`]
+    ///   and here the caller waited on a Docker inspect. If the user stopped
+    ///   and restarted the project meanwhile — same container id, stop/start
+    ///   model — that inspect's "not running" is about a container that has
+    ///   since come back, and flipping would mark a healthy project Stopped.
+    ///   Any write to the store in that window bumps the revision, and the
+    ///   answer is [`ExitMark::Changed`]: confirm again and retry.
+    /// * **`is_busy`** — the project lock. Stop, Start, Reset and migration
+    ///   hold it across their own container's death and write the status they
+    ///   mean themselves. A start that takes the project lock just after this
+    ///   check still blocks on the store lock before it writes `Starting`.
+    ///
+    /// `container_id` may be the short form; the store holds the full id.
+    pub fn mark_exited(
+        &self,
+        container_id: &str,
+        seen: &RunningSighting,
+        is_busy: impl Fn(&str) -> bool,
+    ) -> ExitMark {
+        let mut projects = self.lock();
+        let unchanged = self.revision.load(Ordering::SeqCst) == seen.revision;
+        let Some(p) = projects.iter_mut().find(|p| is_running_on(p, container_id)) else {
+            return ExitMark::NotApplicable;
+        };
+        if !unchanged {
+            return ExitMark::Changed;
+        }
+        if is_busy(&p.id) {
+            return ExitMark::NotApplicable;
+        }
+        p.status = crate::models::ProjectStatus::Stopped;
+        p.updated_at = chrono::Utc::now().to_rfc3339();
+        let changed = p.clone();
+        if let Err(e) = self.save(&projects) {
+            // The in-memory record is what the UI is told about and what every
+            // later command reads, so it stays flipped; the next save of any
+            // kind writes it out.
+            log::warn!("Could not persist Stopped for project {}: {}", changed.id, e);
+        }
+        ExitMark::Flipped(Box::new(changed))
+    }
+
     pub fn update_status(&self, id: &str, status: crate::models::ProjectStatus) -> Result<(), String> {
         let mut projects = self.lock();
         if let Some(p) = projects.iter_mut().find(|p| p.id == id) {
@@ -437,6 +545,7 @@ mod tests {
         ProjectsStore {
             projects: Mutex::new(projects),
             file_path: dir.join("projects.json"),
+            revision: AtomicU64::new(0),
         }
     }
 
@@ -604,4 +713,138 @@ mod tests {
 
         fs::remove_dir_all(&dir).ok();
     }
+
+    // ── running_on / mark_exited: a container that died on its own ───────
+
+    /// A full-length id, as Docker's events and the store both carry.
+    const C0FFEE: &str = "c0ffee0000000000000000000000000000000000000000000000000000000000";
+
+    fn running_on(container_id: &str) -> Project {
+        let mut p = Project::new("p".to_string(), Vec::new());
+        p.container_id = Some(container_id.to_string());
+        p.status = crate::models::ProjectStatus::Running;
+        p
+    }
+
+    /// Sighting and flip back to back, as when Docker answers instantly.
+    fn sight_and_mark(store: &ProjectsStore, cid: &str, busy: impl Fn(&str) -> bool) -> Option<Project> {
+        let seen = store.running_on(cid)?;
+        match store.mark_exited(cid, &seen, busy) {
+            ExitMark::Flipped(p) => Some(*p),
+            _ => None,
+        }
+    }
+
+    #[test]
+    fn a_running_project_whose_container_exited_is_marked_stopped_and_saved() {
+        let dir = temp_dir("exited");
+        let p = running_on(C0FFEE);
+        let id = p.id.clone();
+        let store = store_over(&dir, vec![p]);
+
+        let changed = sight_and_mark(&store, C0FFEE, |_| false).expect("flipped");
+
+        assert_eq!(changed.id, id);
+        assert_eq!(changed.status, crate::models::ProjectStatus::Stopped);
+        assert_eq!(store.get(&id).unwrap().status, crate::models::ProjectStatus::Stopped);
+        let on_disk = fs::read_to_string(dir.join("projects.json")).unwrap();
+        assert!(on_disk.contains("\"stopped\""), "the flip must be persisted: {on_disk}");
+        fs::remove_dir_all(&dir).ok();
+    }
+
+    #[test]
+    fn mark_exited_leaves_a_project_alone_while_a_command_owns_it() {
+        // Stop, Start-with-recreate, Reset and migration all hold the project
+        // lock across their own container's death; the command writes the
+        // status it means, and the watcher must not race it.
+        let dir = temp_dir("busy");
+        let p = running_on(C0FFEE);
+        let id = p.id.clone();
+        let store = store_over(&dir, vec![p]);
+
+        assert!(sight_and_mark(&store, C0FFEE, |pid| pid == id).is_none());
+        assert_eq!(store.get(&id).unwrap().status, crate::models::ProjectStatus::Running);
+        // ...and it was only the claim that held it back.
+        assert!(sight_and_mark(&store, C0FFEE, |_| false).is_some());
+        fs::remove_dir_all(&dir).ok();
+    }
+
+    /// The slow-inspect race. The watcher sights the project Running, then
+    /// waits on Docker; meanwhile the user stops and starts it again on the
+    /// *same* container id (stop/start model). Docker's "not running" is now
+    /// about a container that has come back, so the flip must not land.
+    #[test]
+    fn a_stop_and_start_during_the_docker_check_invalidates_the_sighting() {
+        let dir = temp_dir("restarted");
+        let p = running_on(C0FFEE);
+        let id = p.id.clone();
+        let store = store_over(&dir, vec![p]);
+
+        let seen = store.running_on(C0FFEE).expect("sighted");
+        // ...the inspect is in flight...
+        store.update_status(&id, crate::models::ProjectStatus::Stopping).unwrap();
+        store.update_status(&id, crate::models::ProjectStatus::Stopped).unwrap();
+        store.update_status(&id, crate::models::ProjectStatus::Starting).unwrap();
+        store.update_status(&id, crate::models::ProjectStatus::Running).unwrap();
+
+        assert!(matches!(store.mark_exited(C0FFEE, &seen, |_| false), ExitMark::Changed));
+        assert_eq!(store.get(&id).unwrap().status, crate::models::ProjectStatus::Running);
+        fs::remove_dir_all(&dir).ok();
+    }
+
+    #[test]
+    fn a_stale_sighting_of_a_project_no_longer_running_is_simply_not_applicable() {
+        let dir = temp_dir("gone");
+        let p = running_on(C0FFEE);
+        let id = p.id.clone();
+        let store = store_over(&dir, vec![p]);
+
+        let seen = store.running_on(C0FFEE).expect("sighted");
+        store.update_status(&id, crate::models::ProjectStatus::Stopped).unwrap();
+
+        assert!(matches!(store.mark_exited(C0FFEE, &seen, |_| false), ExitMark::NotApplicable));
+        fs::remove_dir_all(&dir).ok();
+    }
+
+    #[test]
+    fn only_running_projects_on_that_container_are_sighted_or_touched() {
+        let dir = temp_dir("other");
+        let mut starting = running_on(C0FFEE);
+        starting.status = crate::models::ProjectStatus::Starting;
+        let other = running_on(&"b".repeat(64));
+        let (starting_id, other_id) = (starting.id.clone(), other.id.clone());
+        let store = store_over(&dir, vec![starting, other]);
+
+        assert!(store.running_on(C0FFEE).is_none(), "Starting is a command's");
+        assert!(store.running_on(&"d".repeat(64)).is_none(), "nobody's container");
+        assert!(store.running_on("").is_none());
+        assert!(sight_and_mark(&store, C0FFEE, |_| false).is_none());
+        assert_eq!(
+            store.get(&starting_id).unwrap().status,
+            crate::models::ProjectStatus::Starting
+        );
+        assert_eq!(store.get(&other_id).unwrap().status, crate::models::ProjectStatus::Running);
+        fs::remove_dir_all(&dir).ok();
+    }
+
+    #[test]
+    fn a_blank_or_truncated_stored_id_matches_no_container() {
+        // A blank stored id is a prefix of everything.
+        let dir = temp_dir("blank");
+        let store = store_over(&dir, vec![running_on(""), running_on("abc")]);
+        assert!(store.running_on(&"f".repeat(64)).is_none());
+        assert!(store.running_on("abcdef0123456789").is_none());
+        fs::remove_dir_all(&dir).ok();
+    }
+
+    #[test]
+    fn a_short_id_is_matched_against_the_stored_full_one() {
+        let dir = temp_dir("short");
+        let full = "a".repeat(12) + &"b".repeat(52);
+        let store = store_over(&dir, vec![running_on(&full)]);
+
+        assert!(store.running_on("aaaa").is_none(), "too short to be an id");
+        assert!(sight_and_mark(&store, &full[..12], |_| false).is_some());
+        fs::remove_dir_all(&dir).ok();
+    }
 }

app/src/App.tsx

@@ -22,6 +22,7 @@ import { useSTT } from "./hooks/useSTT";
 import { useContainerProgress } from "./hooks/useContainerProgress";
 import { useKeyboardShortcuts } from "./hooks/useKeyboardShortcuts";
 import { useMarketplaceSyncToasts } from "./hooks/useMarketplace";
+import { useProjectStatusEvents } from "./hooks/useProjectStatusEvents";
 import MarketplaceView from "./components/marketplace/MarketplaceView";
 import { useAppState, isHomeTab, tabKeyId, homeTabKey, MARKETPLACE_TAB_KEY } from "./store/appState";
 import { reconcileProjectStatuses } from "./lib/tauri-commands";
@@ -75,6 +76,7 @@ export default function App() {
   useContainerProgress();
   useKeyboardShortcuts();
   useMarketplaceSyncToasts();
+  useProjectStatusEvents();
 
   // Initialize on mount
   useEffect(() => {

app/src/hooks/useProjectStatusEvents.test.ts

@@ -0,0 +1,74 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { renderHook } from "@testing-library/react";
+import { useAppState } from "../store/appState";
+import type { Project } from "../lib/types";
+
+let handler: ((e: { payload: unknown }) => void) | null = null;
+const unlisten = vi.fn();
+const listen = vi.fn(async (name: string, cb: (e: { payload: unknown }) => void) => {
+  if (name === "project-container-exited") handler = cb;
+  return unlisten;
+});
+vi.mock("@tauri-apps/api/event", () => ({
+  listen: (name: string, cb: (e: { payload: unknown }) => void) => listen(name, cb),
+}));
+
+import { useProjectStatusEvents } from "./useProjectStatusEvents";
+
+const project = (over: Partial<Project>): Project =>
+  ({ id: "p1", name: "demo", status: "running", container_id: "c1", ...over }) as Project;
+
+describe("useProjectStatusEvents", () => {
+  beforeEach(() => {
+    handler = null;
+    unlisten.mockClear();
+    listen.mockClear();
+    useAppState.setState({ projects: [project({}), project({ id: "p2", name: "other" })], toasts: [] });
+  });
+
+  it("applies a live exit and says why the sessions just died", async () => {
+    renderHook(() => useProjectStatusEvents());
+    await vi.waitFor(() => expect(handler).not.toBeNull());
+
+    handler!({ payload: { project: project({ status: "stopped" }), reason: "exited" } });
+
+    const { projects, toasts } = useAppState.getState();
+    expect(projects.find((p) => p.id === "p1")?.status).toBe("stopped");
+    expect(projects.find((p) => p.id === "p2")?.status).toBe("running");
+    expect(toasts).toHaveLength(1);
+    expect(toasts[0].kind).toBe("error");
+    expect(toasts[0].message).toContain("demo");
+    expect(toasts[0].dedupeKey).toBe("container-exited-p1");
+  });
+
+  it("applies a container found already stopped at startup silently", async () => {
+    // After a host reboot every project's container is down before the app
+    // opens; nothing was interrupted this run, so nothing to alarm anyone about.
+    renderHook(() => useProjectStatusEvents());
+    await vi.waitFor(() => expect(handler).not.toBeNull());
+
+    handler!({ payload: { project: project({ status: "stopped" }), reason: "found_stopped" } });
+
+    const { projects, toasts } = useAppState.getState();
+    expect(projects.find((p) => p.id === "p1")?.status).toBe("stopped");
+    expect(toasts).toHaveLength(0);
+  });
+
+  it("stops listening on unmount", async () => {
+    const { unmount } = renderHook(() => useProjectStatusEvents());
+    await vi.waitFor(() => expect(handler).not.toBeNull());
+    unmount();
+    expect(unlisten).toHaveBeenCalled();
+  });
+
+  it("survives listen() rejecting (no unhandled rejection)", async () => {
+    const err = vi.spyOn(console, "error").mockImplementation(() => {});
+    listen.mockImplementationOnce(async () => {
+      throw new Error("no IPC");
+    });
+    const { unmount } = renderHook(() => useProjectStatusEvents());
+    await vi.waitFor(() => expect(err).toHaveBeenCalled());
+    unmount();
+    err.mockRestore();
+  });
+});

app/src/hooks/useProjectStatusEvents.ts

@@ -0,0 +1,51 @@
+import { useEffect } from "react";
+import { listen, type UnlistenFn } from "@tauri-apps/api/event";
+import { useAppState } from "../store/appState";
+import type { Project } from "../lib/types";
+
+/** `container_watch.rs`'s `ContainerExited`. */
+export interface ContainerExitedEvent {
+  project: Project;
+  /**
+   * `exited`: it died while the app was running — sessions were just cut off.
+   * `found_stopped`: found down on the app's first look this run (it stopped
+   * while the app was closed, e.g. a host reboot); nothing was interrupted.
+   */
+  reason: "exited" | "found_stopped";
+}
+
+/**
+ * App-wide: apply `project-container-exited` — `container_watch.rs` marking a
+ * project Stopped because its container exited without the app asking. Before
+ * it, the project kept reading Running, with every terminal dead, until the
+ * app was restarted.
+ */
+export function useProjectStatusEvents() {
+  useEffect(() => {
+    let cancelled = false;
+    let unlisten: UnlistenFn | null = null;
+    listen<ContainerExitedEvent>("project-container-exited", (event) => {
+      const { project, reason } = event.payload;
+      const state = useAppState.getState();
+      state.updateProjectInList(project);
+      if (reason !== "exited") return;
+      state.pushToast({
+        kind: "error",
+        message: `The container for “${project.name}” stopped`,
+        detail:
+          "It exited without Triple-C stopping it — open sessions were disconnected. " +
+          "Start the project again to reconnect.",
+        dedupeKey: `container-exited-${project.id}`,
+      });
+    })
+      .then((fn) => {
+        if (cancelled) fn();
+        else unlisten = fn;
+      })
+      .catch((e) => console.error("Failed to listen for container exits:", e));
+    return () => {
+      cancelled = true;
+      unlisten?.();
+    };
+  }, []);
+}

container/entrypoint.sh

@@ -736,6 +736,56 @@ timeout 120 su -s /bin/bash claude -c 'export PATH="/home/claude/.claude/bin:/ho
     && echo "entrypoint: Claude Code is up to date" \
     || echo "entrypoint: warning — Claude Code update skipped or failed (continuing)"
 
-# ── Stay alive as claude ─────────────────────────────────────────────────────
+# ── Stay alive, as root ──────────────────────────────────────────────────────
+# The container lives exactly as long as this script: docker-init is PID 1 and
+# exits when its one child does. So what keeps it alive must be something the
+# claude user cannot kill. This used to end in
+#   exec su -s /bin/bash claude -c "exec sleep infinity"
+# which hung the container's whole lifetime on a `sleep` owned by claude — and
+# Claude Code runs as claude and routinely runs `pkill sleep`, `pkill -f …`,
+# `killall` or `kill -9 -1` while testing something. Any of those stopped the
+# container: every terminal disconnected and the app still said Running.
+# Dropping to claude there bought nothing (it dates from the initial commit,
+# with no stated reason, and nothing reads that process's owner); its one
+# reader is the app's marketplace readiness probe, which now also matches the
+# marker below (app/src-tauri/src/marketplace/sync.rs, READY_PROBE).
+#
+#  * Unprivileged kills get EPERM on both this script and its sleep. Even
+#    `sudo pkill sleep` only kills the child, which the loop replaces; it takes
+#    a root kill of this script itself.
+#  * `docker stop`: docker-init forwards SIGTERM here, and bash runs the trap
+#    as soon as `wait` returns, so the container stops at once rather than
+#    sitting out Docker's grace period and being SIGKILLed.
+#  * The sleep runs as `triple-c-keepalive infinity` (exec -a), a root-owned
+#    command line nothing else has, and it exists only once every step above
+#    has finished — that is the readiness marker. Keep the name in step with
+#    READY_PROBE.
+#  * Respawns are throttled to about one a second. If the sleep cannot start
+#    (fork failing under a pids limit or a fork bomb) or dies at once, an
+#    unthrottled loop would spin a core at 100% exactly when the container is
+#    already in trouble. The pause is `read -t` on a FIFO nobody writes —
+#    a builtin, so it still works when fork does not — with `sleep 1` as the
+#    fallback should the FIFO be unavailable.
 echo "Triple-C container ready."
-exec su -s /bin/bash claude -c "exec sleep infinity"
+keepalive_pid=""
+stop_keepalive() {
+    [ -n "$keepalive_pid" ] && kill "$keepalive_pid" 2>/dev/null
+    exit 0
+}
+trap stop_keepalive TERM INT HUP
+throttle_fifo=/run/triple-c-keepalive.throttle
+rm -f "$throttle_fifo"
+mkfifo -m 600 "$throttle_fifo" 2>/dev/null && exec 3<>"$throttle_fifo"
+rm -f "$throttle_fifo"
+respawn_pause() {
+    read -r -t 1 -u 3 _ 2>/dev/null
+    # >128 is read's timeout, i.e. it paused; anything else means no FIFO.
+    [ $? -gt 128 ] || sleep 1
+}
+while :; do
+    started=$SECONDS
+    (exec -a triple-c-keepalive sleep infinity 3>&-) &
+    keepalive_pid=$!
+    wait "$keepalive_pid"
+    [ $((SECONDS - started)) -ge 2 ] || respawn_pause
+done