feat(host-agent): Phase 2 — Dune docker-compose adapter via Supervisor trait

Introduce a Supervisor trait (async-trait) so the agent manages games with
different models behind one wire contract. ProcessSupervisor (spawned process:
rust/conan/soulmask) and the new DockerComposeSupervisor (dune) both impl it;
Agent.supervisors is now HashMap<String, Arc<dyn Supervisor>> and instancecmd
dispatch is game-agnostic — start/stop/restart/status identical across games,
selected by a per-game factory in main. InstanceState moved to the shared
supervisor module.

DockerComposeSupervisor drives docker-compose up-d / stop / restart against
the instance's compose project, with -f/-p/single-service support and a
configurable compose binary. New [instance.docker_compose] config block.
First cut = lifecycle + cached state; container crash-detection + restart
adoption deferred to Phase 3b (reconcilable with a compose ps probe).

Trait choice (dyn over enum) per Commander: scales to future planes (kubectl,
AMP/podman, SSH) as new struct+impl, no central match.

56 tests green (6 new docker-compose mock-binary tests + 5 refactored process
tests), zero warnings. Live verification pending a real Dune stack.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

corrosion-host-agent/src/docker_compose.rs

@@ -0,0 +1,216 @@
+//! Docker-compose instance supervision — the Dune: Awakening adapter.
+//!
+//! Dune does not ship as a SteamCMD-updated process like Rust/Conan/Soulmask;
+//! it runs as Docker container(s) (game server + RabbitMQ broker + Postgres),
+//! orchestrated as a compose stack (a "battlegroup"). So Dune lifecycle is
+//! `docker compose up -d / stop / restart` against the instance's compose
+//! project, not a spawned OS process. This supervisor implements the same
+//! [`Supervisor`] trait `ProcessSupervisor` does, so the instance command
+//! dispatch is identical — only the management model differs.
+//!
+//! Scope (first cut): lifecycle + cached state. Two parity items are deferred
+//! to Phase 3b alongside process PID adoption: (1) crash detection (containers
+//! give us no child handle — a `docker compose ps` poll loop would supply it);
+//! (2) state adoption on agent restart (a running stack reports `stopped` until
+//! the next lifecycle command). Both are reconcilable with a `ps` probe.
+//!
+//! Reference: docs/reference-repos/icehunter SETUP_DOCKER.md (the docker
+//! control plane this mirrors).
+
+use std::path::PathBuf;
+use std::process::Stdio;
+use std::sync::Arc;
+use std::time::Instant;
+
+use anyhow::{bail, Context, Result};
+use serde::Deserialize;
+use tokio::process::Command;
+use tokio::sync::{watch, Mutex};
+
+use crate::config::InstanceConfig;
+use crate::supervisor::{InstanceState, Supervisor};
+
+/// Per-instance docker-compose settings (`[instance.docker_compose]`). All
+/// fields optional — defaults cover the common "one compose file in the
+/// instance root" case.
+#[derive(Debug, Clone, Default, Deserialize)]
+#[serde(deny_unknown_fields)]
+pub struct DockerComposeConfig {
+    /// Compose file (`-f`). Relative paths resolve against the run dir. Default:
+    /// compose's own discovery (docker-compose.yml in the run dir).
+    #[serde(default)]
+    pub file: Option<PathBuf>,
+    /// Compose project name (`-p`). Default: the instance id.
+    #[serde(default)]
+    pub project: Option<String>,
+    /// Limit lifecycle ops to one service. Default: every service in the file.
+    #[serde(default)]
+    pub service: Option<String>,
+    /// Override the compose binary invocation. Default: `["docker","compose"]`.
+    /// Use `["docker-compose"]` for the legacy standalone binary.
+    #[serde(default)]
+    pub command: Option<Vec<String>>,
+}
+
+struct Inner {
+    started_at: Option<Instant>,
+}
+
+pub struct DockerComposeSupervisor {
+    instance_id: String,
+    /// Directory the compose commands run in (relative `-f`/file paths resolve
+    /// against it).
+    run_dir: PathBuf,
+    compose_file: Option<PathBuf>,
+    project: String,
+    service: Option<String>,
+    /// Compose binary + leading args, e.g. `["docker","compose"]`.
+    command: Vec<String>,
+    inner: Mutex<Inner>,
+    state_tx: watch::Sender<InstanceState>,
+}
+
+impl DockerComposeSupervisor {
+    pub fn new(cfg: &InstanceConfig) -> Arc<Self> {
+        let dc = cfg.docker_compose.clone().unwrap_or_default();
+        let run_dir = cfg
+            .working_dir
+            .clone()
+            .unwrap_or_else(|| cfg.root.clone());
+        let command = dc
+            .command
+            .filter(|c| !c.is_empty())
+            .unwrap_or_else(|| vec!["docker".to_string(), "compose".to_string()]);
+        let (state_tx, _) = watch::channel(InstanceState::Stopped);
+        Arc::new(Self {
+            instance_id: cfg.id.clone(),
+            run_dir,
+            compose_file: dc.file,
+            project: dc.project.unwrap_or_else(|| cfg.id.clone()),
+            service: dc.service,
+            command,
+            inner: Mutex::new(Inner { started_at: None }),
+            state_tx,
+        })
+    }
+
+    fn set_state(&self, state: InstanceState) {
+        let _ = self.state_tx.send_replace(state);
+    }
+
+    /// Run one compose subcommand (`up`/`stop`/`restart`/...), bailing with the
+    /// captured stderr on non-zero exit. Global flags (`-f`, `-p`) precede the
+    /// subcommand; the optional single service is appended last.
+    async fn run(&self, action: &str, action_args: &[&str]) -> Result<()> {
+        let mut cmd = Command::new(&self.command[0]);
+        cmd.args(&self.command[1..]);
+        if let Some(file) = &self.compose_file {
+            cmd.arg("-f").arg(file);
+        }
+        cmd.arg("-p").arg(&self.project);
+        cmd.arg(action);
+        cmd.args(action_args);
+        if let Some(service) = &self.service {
+            cmd.arg(service);
+        }
+        cmd.current_dir(&self.run_dir)
+            .stdin(Stdio::null())
+            .stdout(Stdio::piped())
+            .stderr(Stdio::piped());
+
+        let output = cmd
+            .output()
+            .await
+            .with_context(|| format!("running `{} {action}` (is docker installed and on PATH?)", self.command.join(" ")))?;
+
+        if !output.status.success() {
+            let stderr = String::from_utf8_lossy(&output.stderr);
+            let stdout = String::from_utf8_lossy(&output.stdout);
+            let detail = if !stderr.trim().is_empty() {
+                stderr.trim()
+            } else {
+                stdout.trim()
+            };
+            bail!("compose {action} failed ({}): {detail}", output.status);
+        }
+        Ok(())
+    }
+}
+
+#[async_trait::async_trait]
+impl Supervisor for DockerComposeSupervisor {
+    fn instance_id(&self) -> &str {
+        &self.instance_id
+    }
+
+    fn state(&self) -> InstanceState {
+        self.state_tx.borrow().clone()
+    }
+
+    fn watch_state(&self) -> watch::Receiver<InstanceState> {
+        self.state_tx.subscribe()
+    }
+
+    async fn uptime_seconds(&self) -> u64 {
+        let inner = self.inner.lock().await;
+        match (&*self.state_tx.borrow(), inner.started_at) {
+            (InstanceState::Running, Some(t)) => t.elapsed().as_secs(),
+            _ => 0,
+        }
+    }
+
+    async fn start(self: Arc<Self>) -> Result<()> {
+        if matches!(
+            *self.state_tx.borrow(),
+            InstanceState::Running | InstanceState::Starting
+        ) {
+            bail!("instance '{}' is already running", self.instance_id);
+        }
+        self.set_state(InstanceState::Starting);
+        match self.run("up", &["-d"]).await {
+            Ok(()) => {
+                self.inner.lock().await.started_at = Some(Instant::now());
+                self.set_state(InstanceState::Running);
+                tracing::info!("instance '{}' compose up -d", self.instance_id);
+                Ok(())
+            }
+            Err(e) => {
+                self.set_state(InstanceState::Stopped);
+                Err(e)
+            }
+        }
+    }
+
+    async fn stop(self: Arc<Self>) -> Result<()> {
+        self.set_state(InstanceState::Stopping);
+        match self.run("stop", &[]).await {
+            Ok(()) => {
+                self.inner.lock().await.started_at = None;
+                self.set_state(InstanceState::Stopped);
+                tracing::info!("instance '{}' compose stop", self.instance_id);
+                Ok(())
+            }
+            Err(e) => {
+                // Stop failed — the stack is most likely still up.
+                self.set_state(InstanceState::Running);
+                Err(e)
+            }
+        }
+    }
+
+    async fn restart(self: Arc<Self>) -> Result<()> {
+        self.set_state(InstanceState::Starting);
+        match self.run("restart", &[]).await {
+            Ok(()) => {
+                self.inner.lock().await.started_at = Some(Instant::now());
+                self.set_state(InstanceState::Running);
+                tracing::info!("instance '{}' compose restart", self.instance_id);
+                Ok(())
+            }
+            Err(e) => {
+                self.set_state(InstanceState::Stopped);
+                Err(e)
+            }
+        }
+    }
+}