Merge pull request 'Host abstraction, phase 1a: ContainerTarget for container-interior operations' (#74) from refactor/project-host into main

- ExecSessionManager::get_target replaces get_container_id, so image paste,
  file drop and the audio bridge reuse the session's own target instead of
  rebuilding a Docker one; the web terminal builds its target per project.
- Drop the error-prefix rewriting helper: download/backup/run-now errors now
  carry the host layer's own message after their prefix.
- Remove the now-unused create_attached_exec and MAX_ONESHOT_OUTPUT re-export.
- The boundary test's allowlist is down to migration (Docker-only) and
  container_watch (phase 1b). CLAUDE.md documents the host layer.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CLAUDE.md

@@ -264,8 +264,8 @@ docker exec stdout → tokio task → emit("terminal-output-{sessionId}") → li
 - **`docker/`** — Docker API layer using bollard:
   - `client.rs` — Singleton Docker connection via `OnceLock`
   - `container.rs` — Container lifecycle (create, start, stop, remove, inspect)
-  - `exec.rs` — Attached exec streaming. `create_attached_exec()` is the **single** place an
-    attached exec is opened; terminal sessions and the auth bridge both go through it.
+  - `exec.rs` — Docker's implementation of everything `host::ContainerTarget` does inside a
+    container. `create_attached_exec_spec()` is the **single** place an attached exec is opened.
   - `image.rs` — Image build/pull with progress streaming
   - `gateway.rs` — Optional LiteLLM sibling container giving Claude Code an Anthropic-format
     front end for providers that only speak OpenAI (see `gateway-container/`). Mirrors `stt.rs`.
@@ -282,6 +282,15 @@ docker exec stdout → tokio task → emit("terminal-output-{sessionId}") → li
   - `legacy_cleanup.rs` — One-release migration shim removing leftovers from the deleted MCP
     feature (containers labelled `triple-c.mcp-server`, `triple-c-net-*` networks). Deletable once
     users have migrated.
+- **`host/`** — Where a project's container runs, and the only way into it. `ContainerTarget`
+  (one `Docker` variant today; AWS planned — `docs/superpowers/specs/2026-11-13-aws-ecs-host-design.md`)
+  wraps execs, file transfer and `is_running`; `sessions.rs` holds `ExecSessionManager`.
+  **Container-interior code must go through `ContainerTarget`, never `docker::exec`, bollard or
+  `get_docker()`** — `host::tests::no_container_interior_bollard_outside_the_host_layer` fails
+  the build on it. Its allowlist is Docker-only code (migration) plus lifecycle/`die` events,
+  which phase 1b moves; shrink it, never grow it. Prefer `ContainerTarget::for_project` or a
+  target a session already holds (`ExecSessionManager::get_target`) over
+  `ContainerTarget::docker(id)`, which hard-codes the host.
 - **`web_terminal/`** — Remote terminal access via axum HTTP+WebSocket server:
   - `server.rs` — Axum server lifecycle (start/stop), serves embedded HTML and handles WS upgrades
   - `ws_handler.rs` — Per-connection WebSocket handler with JSON protocol, session management, cleanup on disconnect

app/src-tauri/Cargo.lock

@@ -6618,6 +6618,7 @@ dependencies = [
  "axum",
  "base64 0.22.1",
  "bollard",
+ "bytes",
  "chrono",
  "dirs",
  "fern",

app/src-tauri/Cargo.toml

@@ -21,6 +21,7 @@ bollard = "0.18"
 keyring = { version = "3", features = ["apple-native", "windows-native", "linux-native"] }
 tokio = { version = "1", features = ["full"] }
 futures-util = "0.3"
+bytes = "1"
 uuid = { version = "1", features = ["v4"] }
 chrono = { version = "0.4", features = ["serde"] }
 dirs = "6"

app/src-tauri/src/auth_bridge/mod.rs

@@ -32,7 +32,7 @@
 //! |---|---|
 //! | Bridge disabled | `set_auth_bridge_enabled(false)` → [`AuthBridgeManager::stop`] |
 //! | Container stopped via UI | `stop_project_container` → [`AuthBridgeManager::stop`] |
-//! | Container stopped/died another way | poller's own `is_container_running` check → loop exits |
+//! | Container stopped/died another way | poller's own `is_running` check → loop exits |
 //! | Project deleted | `remove_project` → [`AuthBridgeManager::stop`]; also the poller's `store.get()` check |
 //! | Container rebuilt | `rebuild_project_container` → stop, then start re-arms it |
 //! | App exit | window `CloseRequested` → [`AuthBridgeManager::stop_all`] |
@@ -55,8 +55,7 @@ use tauri::{AppHandle, Emitter};
 use tokio::sync::{watch, Mutex};
 use tokio::task::JoinHandle;
 
-use crate::docker::container::is_container_running;
-use crate::docker::exec::{exec_oneshot_limited, PROC_NET_OUTPUT_LIMIT};
+use crate::host::{ContainerTarget, PROC_NET_OUTPUT_LIMIT};
 use crate::storage::projects_store::ProjectsStore;
 
 use proc_net::PortFamily;
@@ -205,7 +204,7 @@ impl AuthBridgeManager {
 
         let poller = tokio::spawn(poll_loop(
             project_id.clone(),
-            container_id,
+            ContainerTarget::docker(container_id),
             epoch,
             app,
             store,
@@ -276,7 +275,7 @@ impl AuthBridgeManager {
 #[allow(clippy::too_many_arguments)]
 async fn poll_loop(
     project_id: String,
-    container_id: String,
+    container: ContainerTarget,
     epoch: u64,
     app: AppHandle,
     store: Arc<ProjectsStore>,
@@ -301,7 +300,7 @@ async fn poll_loop(
             log::info!("Auth bridge: disabled for project {} — tearing down", project_id);
             break;
         }
-        if !is_container_running(&container_id).await.unwrap_or(false) {
+        if !container.is_running().await.unwrap_or(false) {
             log::info!(
                 "Auth bridge: container for project {} is no longer running — tearing down",
                 project_id
@@ -327,7 +326,7 @@ async fn poll_loop(
         // bridge or stopping the container doesn't wait out an in-flight poll.
         let discovery = tokio::select! {
             _ = cancel.changed() => break,
-            res = exec_oneshot_limited(&container_id, "claude", cmd, PROC_NET_OUTPUT_LIMIT) => {
+            res = container.exec_oneshot_limited("claude", cmd, PROC_NET_OUTPUT_LIMIT) => {
                 res.map(|(out, _)| out)
             }
         };
@@ -340,7 +339,7 @@ async fn poll_loop(
                 // gateway/STT/web-terminal ports can be re-pointed while the
                 // bridge is running, and a stale reservation set is a hole.
                 let skip = skipped_ports(&project, &store.list(), &app_settings(&app));
-                if reconcile(&container_id, &discovered, &skip, &state).await {
+                if reconcile(&container, &discovered, &skip, &state).await {
                     emit_status(&app, &project_id, &state, true).await;
                 }
             }
@@ -530,7 +529,7 @@ const MAX_CONFLICTS: usize = 32;
 /// Bring the set of host listeners in line with what the container is currently
 /// listening on. Returns whether anything the UI cares about changed.
 async fn reconcile(
-    container_id: &str,
+    container: &ContainerTarget,
     discovered: &BTreeMap<u16, PortFamily>,
     skip: &HashSet<u16>,
     state: &Arc<Mutex<BridgeState>>,
@@ -583,7 +582,7 @@ async fn reconcile(
             );
             continue;
         }
-        match PortForward::bind(container_id.to_string(), port, family).await {
+        match PortForward::bind(container.clone(), port, family).await {
             Ok(forward) => {
                 if st.conflicts.remove(&port).is_some() {
                     log::info!("Auth bridge: host port {} became available", port);
@@ -833,7 +832,13 @@ mod tests {
             (45000u16..45200).map(|p| (p, PortFamily::V4)).collect();
         let state = Arc::new(Mutex::new(BridgeState::default()));
 
-        reconcile("no-such-container", &discovered, &HashSet::new(), &state).await;
+        reconcile(
+            &ContainerTarget::docker("no-such-container"),
+            &discovered,
+            &HashSet::new(),
+            &state,
+        )
+        .await;
 
         let mut st = state.lock().await;
         assert!(

app/src-tauri/src/auth_bridge/tunnel.rs

@@ -11,7 +11,7 @@
 //! and stdout wired to the TCP socket. `socat` ships in the container image.
 //!
 //! The exec plumbing itself is *not* reimplemented here: it comes from
-//! [`crate::docker::exec::create_attached_exec`], the same helper the
+//! [`crate::host::ContainerTarget::attach_exec`], the same helper the
 //! interactive terminal sessions are built on.
 //!
 //! ## What the host listener is, and is not
@@ -56,14 +56,12 @@
 use std::net::{Ipv4Addr, Ipv6Addr, SocketAddr};
 use std::time::Duration;
 
-use bollard::container::LogOutput;
+use crate::host::{AttachedExec, ContainerTarget, ExecChunk};
 use futures_util::StreamExt;
 use tokio::io::{AsyncReadExt, AsyncWriteExt};
 use tokio::net::{TcpListener, TcpStream};
 use tokio::task::{JoinHandle, JoinSet};
 
-use crate::docker::exec::{create_attached_exec, AttachedExec};
-
 use super::proc_net::PortFamily;
 
 /// Buffer size for the host→container direction. OAuth callbacks are tiny; this
@@ -143,13 +141,13 @@ impl Drop for PortForward {
 }
 
 impl PortForward {
-    /// Bind `port` on the host loopback and start proxying into `container_id`.
+    /// Bind `port` on the host loopback and start proxying into `container`.
     ///
     /// The bind happens before the task is spawned, so an already-taken port is
     /// reported to the caller as an error rather than disappearing into a
     /// background task.
     pub async fn bind(
-        container_id: String,
+        container: ContainerTarget,
         port: u16,
         family: PortFamily,
     ) -> Result<Self, std::io::Error> {
@@ -196,7 +194,7 @@ impl PortForward {
             };
 
         let target = family.socat_target(port);
-        let task = tokio::spawn(accept_loop(container_id, port, target, v4, v6));
+        let task = tokio::spawn(accept_loop(container, port, target, v4, v6));
 
         Ok(Self {
             port,
@@ -219,7 +217,7 @@ impl PortForward {
 /// Accept on both loopback listeners until aborted. Dropping this future drops
 /// the listeners (freeing the port) and the `JoinSet` (aborting live tunnels).
 async fn accept_loop(
-    container_id: String,
+    container: ContainerTarget,
     port: u16,
     target: String,
     v4: TcpListener,
@@ -258,7 +256,7 @@ async fn accept_loop(
                 log::debug!("Auth bridge: connection from {} to bridged port {}", peer, port);
                 let _ = stream.set_nodelay(true);
                 conns.spawn(tunnel_connection(
-                    container_id.clone(),
+                    container.clone(),
                     target.clone(),
                     stream,
                     port,
@@ -288,7 +286,12 @@ async fn accept_optional(
 ///
 /// Nothing is forwarded until that decision is made, so a refused request never
 /// reaches the container at all — not even a `docker exec`.
-async fn tunnel_connection(container_id: String, target: String, mut stream: TcpStream, port: u16) {
+async fn tunnel_connection(
+    container: ContainerTarget,
+    target: String,
+    mut stream: TcpStream,
+    port: u16,
+) {
     let head = match read_leading_bytes(&mut stream).await {
         Ok(head) => head,
         Err(e) => {
@@ -319,7 +322,7 @@ async fn tunnel_connection(container_id: String, target: String, mut stream: Tcp
     }
 
     // The bytes already off the socket go back on the wire first, byte-exact.
-    tunnel_connection_with_prelude(container_id, target, stream, port, head.into_buffer()).await
+    tunnel_into_with_prelude(container, target, stream, port, head.into_buffer()).await
 }
 
 /// What the first bytes of an accepted connection turned out to be.
@@ -511,12 +514,34 @@ pub(crate) fn web_request_verdict(head: &str) -> Verdict {
 /// head off the socket to check a token, and then has to put those same bytes
 /// back on the wire. Passing them here keeps the byte stream exact, rather than
 /// re-serialising a parsed request.
+///
+/// Takes a Docker container id because that is what the browser-view proxy
+/// holds; [`tunnel_into_with_prelude`] is the same thing for a
+/// [`ContainerTarget`] already in hand.
 pub async fn tunnel_connection_with_prelude(
     container_id: String,
     target: String,
     stream: TcpStream,
     port: u16,
     prelude: Vec<u8>,
+) {
+    tunnel_into_with_prelude(
+        ContainerTarget::docker(container_id),
+        target,
+        stream,
+        port,
+        prelude,
+    )
+    .await
+}
+
+/// [`tunnel_connection_with_prelude`] for a [`ContainerTarget`].
+pub async fn tunnel_into_with_prelude(
+    container: ContainerTarget,
+    target: String,
+    stream: TcpStream,
+    port: u16,
+    prelude: Vec<u8>,
 ) {
     let cmd = vec!["socat".to_string(), "-".to_string(), target.clone()];
 
@@ -524,7 +549,7 @@ pub async fn tunnel_connection_with_prelude(
         mut output,
         mut input,
         ..
-    } = match create_attached_exec(&container_id, cmd, false).await {
+    } = match container.attach_exec(cmd, false).await {
         Ok(e) => e,
         Err(e) => {
             log::warn!(
@@ -587,12 +612,12 @@ pub async fn tunnel_connection_with_prelude(
             // Only stdout is payload. The exec is created with tty = false
             // precisely so Docker demultiplexes these, keeping socat's stderr
             // diagnostics out of the proxied byte stream.
-            Ok(LogOutput::StdOut { message }) => {
+            Ok(ExecChunk::StdOut(message)) => {
                 if host_tx.write_all(&message).await.is_err() {
                     break;
                 }
             }
-            Ok(LogOutput::StdErr { message }) => {
+            Ok(ExecChunk::StdErr(message)) => {
                 log::debug!(
                     "Auth bridge: socat stderr for port {}: {}",
                     port,

app/src-tauri/src/browser_view/detect.rs

@@ -36,7 +36,7 @@
 
 use serde::{Deserialize, Serialize};
 
-use crate::docker::exec::exec_oneshot;
+use crate::host::ContainerTarget;
 
 /// Marks the JSON payload in the probe's stdout, so unrelated chatter on the
 /// same stream (npm notices, Node warnings) can't be mistaken for the result.
@@ -278,11 +278,18 @@ impl PlaywrightDetection {
 /// `npx @playwright/mcp`, is found as readily as one in
 /// `/workspace/node_modules`.
 pub async fn detect(container_id: &str) -> Result<PlaywrightDetection, String> {
-    let output = exec_oneshot(
-        container_id,
-        vec!["node".to_string(), "-e".to_string(), PROBE.to_string()],
-    )
-    .await?;
+    detect_in(&ContainerTarget::docker(container_id)).await
+}
+
+/// [`detect`] against a target already in hand.
+pub async fn detect_in(container: &ContainerTarget) -> Result<PlaywrightDetection, String> {
+    let output = container
+        .exec_oneshot(vec![
+            "node".to_string(),
+            "-e".to_string(),
+            PROBE.to_string(),
+        ])
+        .await?;
 
     parse_probe_output(&output)
 }

app/src-tauri/src/browser_view/install.rs

@@ -67,9 +67,7 @@ use serde::Serialize;
 use tauri::AppHandle;
 
 use crate::commands::project_commands::emit_progress;
-use crate::docker::exec::{
-    create_attached_exec_as, exec_oneshot_as, wait_for_exec_exit, AttachedExec,
-};
+use crate::host::{AttachedExec, ContainerTarget, ExecSpec};
 
 use super::detect::{self, PlaywrightDetection};
 
@@ -242,13 +240,14 @@ pub async fn install_packages(
     project_id: &str,
     container_id: &str,
 ) -> Result<BrowserSetupOutcome, String> {
+    let container = ContainerTarget::docker(container_id);
     emit_progress(
         app,
         project_id,
         &format!("Installing @playwright/cli into {}/node_modules…", INSTALL_DIR),
     );
 
-    let mut step = npm_install(app, project_id, container_id, &[VIEWER_PACKAGE]).await?;
+    let mut step = npm_install(app, project_id, &container, &[VIEWER_PACKAGE]).await?;
     if step.exit_code != 0 {
         return Err(format!(
             "npm couldn't install the viewer package in this container (exit {}).\n\nnpm said:\n{}",
@@ -265,9 +264,9 @@ pub async fn install_packages(
     // see the note on `npm_install`. The pin can only be read after the first
     // install has written the manifest, which is why this stays two commands
     // rather than one.
-    let spec = pinned_playwright_spec(container_id).await;
+    let spec = pinned_playwright_spec(&container).await;
     emit_progress(app, project_id, &format!("Installing {}…", spec));
-    let second = npm_install(app, project_id, container_id, &[VIEWER_PACKAGE, &spec]).await?;
+    let second = npm_install(app, project_id, &container, &[VIEWER_PACKAGE, &spec]).await?;
     if second.exit_code != 0 {
         return Err(format!(
             "npm couldn't install {} in this container (exit {}).\n\nnpm said:\n{}",
@@ -279,7 +278,7 @@ pub async fn install_packages(
     step.log = merge_logs(step.log, second.log);
 
     emit_progress(app, project_id, "Re-checking what the container has…");
-    let detection = detect::detect(container_id).await?;
+    let detection = detect::detect_in(&container).await?;
 
     // A probe that still finds something missing after a successful npm run is
     // the interesting case, so it is surfaced rather than swallowed. And a
@@ -331,7 +330,7 @@ pub async fn install_packages(
 async fn npm_install(
     app: &AppHandle,
     project_id: &str,
-    container_id: &str,
+    container: &ContainerTarget,
     specs: &[&str],
 ) -> Result<StepResult, String> {
     let mut cmd = vec![
@@ -348,7 +347,7 @@ async fn npm_install(
     run_step(
         app,
         project_id,
-        container_id,
+        container,
         "claude",
         INSTALL_DIR,
         cmd,
@@ -363,20 +362,20 @@ async fn npm_install(
 /// Read from the manifest npm just wrote rather than guessed, and falling back
 /// to `@latest` when it can't be read — an unreadable manifest is a reason to
 /// install something, not nothing.
-async fn pinned_playwright_spec(container_id: &str) -> String {
+async fn pinned_playwright_spec(container: &ContainerTarget) -> String {
     let script = format!(
         "try{{const d=require('{}/node_modules/@playwright/cli/package.json').dependencies||{{}};\
          process.stdout.write(d.playwright||'');}}catch(e){{}}",
         INSTALL_DIR
     );
-    let (out, _code) = exec_oneshot_as(
-        container_id,
-        "claude",
-        vec!["node".to_string(), "-e".to_string(), script],
-        Vec::new(),
-    )
-    .await
-    .unwrap_or_default();
+    let (out, _code) = container
+        .exec_oneshot_as(
+            "claude",
+            vec!["node".to_string(), "-e".to_string(), script],
+            Vec::new(),
+        )
+        .await
+        .unwrap_or_default();
 
     let version: &str = out.trim();
     // A version, not a range or a URL: anything else goes to the fallback
@@ -414,7 +413,8 @@ pub async fn install_browser(
     container_id: &str,
     target: BrowserTarget,
 ) -> Result<BrowserSetupOutcome, String> {
-    let before = detect::detect(container_id).await?;
+    let container = ContainerTarget::docker(container_id);
+    let before = detect::detect_in(&container).await?;
     let Some(cli) = before.playwright_cli.clone() else {
         return Err(
             "Playwright isn't installed in this container yet, so there is nothing to install a \
@@ -458,7 +458,7 @@ pub async fn install_browser(
         project_id,
         "Step 1/3 — checking whether this container already has the browser system libraries…",
     );
-    let state = check_libraries(container_id, &cli, target).await;
+    let state = check_libraries(&container, &cli, target).await;
     match &state {
         LibraryState::Present => {
             emit_progress(
@@ -482,7 +482,7 @@ pub async fn install_browser(
             let deps = run_step(
                 app,
                 project_id,
-                container_id,
+                &container,
                 "root",
                 "/tmp",
                 vec![
@@ -530,7 +530,7 @@ pub async fn install_browser(
     let dl = run_step(
         app,
         project_id,
-        container_id,
+        &container,
         user,
         workdir,
         vec![
@@ -559,7 +559,7 @@ pub async fn install_browser(
         project_id,
         &format!("Step 3/3 — checking that {} actually launches…", target.cli_name()),
     );
-    let verdict = verify_launch(container_id, &before, target).await;
+    let verdict = verify_launch(&container, &before, target).await;
     push_section(&mut log, &verdict.detail);
     if !verdict.ok {
         warning = merge(
@@ -590,7 +590,7 @@ pub async fn install_browser(
     }
 
     emit_progress(app, project_id, "Re-checking what the container has…");
-    let detection = detect::detect(container_id).await?;
+    let detection = detect::detect_in(&container).await?;
 
     Ok(BrowserSetupOutcome {
         detection,
@@ -642,9 +642,12 @@ impl LibraryState {
 /// dpkg's status file. A *missing* package on such an image is simply not in
 /// any index, so apt fails, Playwright reports the failure, and this returns
 /// [`LibraryState::Unknown`] — which installs, which is the right answer.
-async fn check_libraries(container_id: &str, cli: &str, target: BrowserTarget) -> LibraryState {
-    let run = exec_oneshot_as(
-        container_id,
+async fn check_libraries(
+    container: &ContainerTarget,
+    cli: &str,
+    target: BrowserTarget,
+) -> LibraryState {
+    let run = container.exec_oneshot_as(
         "root",
         vec![
             "node".to_string(),
@@ -708,7 +711,7 @@ struct LaunchVerdict {
 /// Launch the browser headless, load one page, and close it. Seconds, and it is
 /// the only thing that distinguishes "downloaded" from "usable".
 async fn verify_launch(
-    container_id: &str,
+    container: &ContainerTarget,
     detection: &PlaywrightDetection,
     target: BrowserTarget,
 ) -> LaunchVerdict {
@@ -724,8 +727,7 @@ async fn verify_launch(
     };
     let dir = manifest.trim_end_matches("package.json").trim_end_matches('/');
 
-    let run = exec_oneshot_as(
-        container_id,
+    let run = container.exec_oneshot_as(
         "claude",
         vec![
             "node".to_string(),
@@ -884,13 +886,13 @@ impl StepResult {
 /// Run one command in the container, streaming every line it prints to the pane
 /// as `container-progress` and keeping the tail for the result.
 ///
-/// Uses `create_attached_exec_as` — the single attached-exec path — rather than
+/// Uses [`ContainerTarget::attach`] — the single attached-exec path — rather than
 /// `exec_oneshot`, because these commands run for minutes and the point is that
 /// the user can watch them.
 async fn run_step(
     app: &AppHandle,
     project_id: &str,
-    container_id: &str,
+    container: &ContainerTarget,
     user: &str,
     workdir: &str,
     cmd: Vec<String>,
@@ -900,7 +902,14 @@ async fn run_step(
         exec_id,
         mut output,
         input,
-    } = create_attached_exec_as(container_id, cmd, false, user, workdir).await?;
+    } = container
+        .attach(
+            ExecSpec::new(cmd)
+                .tty(false)
+                .user(user)
+                .working_dir(Some(workdir)),
+        )
+        .await?;
 
     // Nothing is ever written to this exec. Closing stdin means anything that
     // would prompt sees EOF and gives up, instead of waiting for a person who
@@ -944,7 +953,7 @@ async fn run_step(
         )),
         Ok(Err(e)) => Err(e),
         Ok(Ok(())) => Ok(StepResult {
-            exit_code: wait_for_exec_exit(&exec_id).await.unwrap_or(0),
+            exit_code: container.wait_exec_exit(&exec_id).await.unwrap_or(0),
             log,
         }),
     }

app/src-tauri/src/browser_view/mod.rs

@@ -50,7 +50,7 @@
 //! | Trigger | Path |
 //! |---|---|
 //! | Turned off in the UI | `set_browser_view_enabled(false)` → persist `false`, then [`BrowserViewManager::stop`] |
-//! | Container stopped, by the UI or otherwise | supervisor's `is_container_running` check |
+//! | Container stopped, by the UI or otherwise | supervisor's `is_running` check |
 //! | Project deleted | supervisor's `store.get()` check |
 //! | Container rebuilt | old container stops → supervisor exits; the new one is not auto-started |
 //! | Viewer died in the container | supervisor's periodic HTTP liveness probe |
@@ -90,8 +90,7 @@ use tokio::sync::{watch, Mutex};
 use tokio::task::JoinHandle;
 
 use crate::auth_bridge::proc_net::{self, PortFamily};
-use crate::docker::container::is_container_running;
-use crate::docker::exec::exec_oneshot;
+use crate::host::ContainerTarget;
 use crate::storage::projects_store::ProjectsStore;
 
 use detect::PlaywrightDetection;
@@ -300,7 +299,8 @@ impl BrowserViewManager {
             return Ok(self.status(&project_id, true).await);
         }
 
-        let detection = detect::detect(&container_id).await?;
+        let container = ContainerTarget::docker(container_id.as_str());
+        let detection = detect::detect_in(&container).await?;
         if !detection.is_usable() {
             let blocker = detection.blocker().unwrap_or_else(|| {
                 "Playwright is present but incomplete in this container.".to_string()
@@ -320,9 +320,9 @@ impl BrowserViewManager {
         // Doing this before choosing a port also frees the one a previous
         // session was using, so sessions don't walk up the range. Best-effort:
         // a container with no dashboard makes this a no-op.
-        let _ = kill_dashboard(&container_id, &cli_entry).await;
+        let _ = kill_dashboard(&container, &cli_entry).await;
 
-        let (container_port, entry_path) = start_viewer(&container_id, &cli_entry).await?;
+        let (container_port, entry_path) = start_viewer(&container, &cli_entry).await?;
 
         let token = generate_token();
         // `--host 127.0.0.1` is ours to set, so the family is known and there is
@@ -337,7 +337,7 @@ impl BrowserViewManager {
         {
             Ok(p) => p,
             Err(e) => {
-                let _ = kill_dashboard(&container_id, &cli_entry).await;
+                let _ = kill_dashboard(&container, &cli_entry).await;
                 return Err(e);
             }
         };
@@ -354,7 +354,7 @@ impl BrowserViewManager {
         let (cancel_tx, cancel_rx) = watch::channel(false);
         let supervisor = tokio::spawn(supervise(
             project_id.clone(),
-            container_id.clone(),
+            container,
             cli_entry,
             container_port,
             epoch,
@@ -427,7 +427,7 @@ impl BrowserViewManager {
 #[allow(clippy::too_many_arguments)]
 async fn supervise(
     project_id: String,
-    container_id: String,
+    container: ContainerTarget,
     cli_entry: String,
     container_port: u16,
     epoch: u64,
@@ -443,7 +443,7 @@ async fn supervise(
             log::info!("Browser view: project {} is gone — tearing down", project_id);
             break;
         }
-        if !is_container_running(&container_id).await.unwrap_or(false) {
+        if !container.is_running().await.unwrap_or(false) {
             log::info!(
                 "Browser view: container for project {} is no longer running — tearing down",
                 project_id
@@ -459,7 +459,7 @@ async fn supervise(
             // view never waits out an in-flight exec.
             let alive = tokio::select! {
                 _ = cancel.changed() => break,
-                res = probe_entry_path(&container_id, container_port) => res.is_ok(),
+                res = probe_entry_path(&container, container_port) => res.is_ok(),
             };
             if !alive {
                 log::warn!(
@@ -477,7 +477,7 @@ async fn supervise(
     }
 
     proxy.shutdown().await;
-    let _ = kill_dashboard(&container_id, &cli_entry).await;
+    let _ = kill_dashboard(&container, &cli_entry).await;
 
     // Deregister, unless a newer session has already taken this project's slot.
     let superseded = {
@@ -538,7 +538,11 @@ const VIEWER_LOG: &str = "/tmp/triple-c-browser-view.log";
 /// redirected to [`VIEWER_LOG`] (both so `exec_oneshot` can return immediately
 /// rather than waiting on an inherited stdout, and so a failure has a trail),
 /// and readiness is established by [`wait_until_ready`] instead.
-async fn launch_viewer(container_id: &str, cli_entry: &str, port: u16) -> Result<(), String> {
+async fn launch_viewer(
+    container: &ContainerTarget,
+    cli_entry: &str,
+    port: u16,
+) -> Result<(), String> {
     // `NO_UPDATE_NOTIFIER` stops the CLI phoning registry.npmjs.org on every
     // launch; the container may have no egress, and we don't want to wait out a
     // DNS timeout before the dashboard binds.
@@ -549,13 +553,11 @@ async fn launch_viewer(container_id: &str, cli_entry: &str, port: u16) -> Result
         port,
         VIEWER_LOG
     );
-    exec_oneshot(
-        container_id,
-        vec!["sh".to_string(), "-c".to_string(), script],
-    )
-    .await
-    .map(|_| ())
-    .map_err(|e| format!("Could not start the Playwright viewer: {}", e))
+    container
+        .exec_oneshot(vec!["sh".to_string(), "-c".to_string(), script])
+        .await
+        .map(|_| ())
+        .map_err(|e| format!("Could not start the Playwright viewer: {}", e))
 }
 
 /// The dashboard singleton is keyed on a hash of the working directory, so
@@ -567,17 +569,15 @@ async fn launch_viewer(container_id: &str, cli_entry: &str, port: u16) -> Result
 const WORKDIR_PREFIX: &str = "cd /workspace 2>/dev/null || true";
 
 /// Stop the dashboard daemon. Verified to free the port and stop answering.
-async fn kill_dashboard(container_id: &str, cli_entry: &str) -> Result<String, String> {
+async fn kill_dashboard(container: &ContainerTarget, cli_entry: &str) -> Result<String, String> {
     let script = format!(
         "{}; NO_UPDATE_NOTIFIER=1 node {} show --kill",
         WORKDIR_PREFIX,
         shell_quote(cli_entry)
     );
-    exec_oneshot(
-        container_id,
-        vec!["sh".to_string(), "-c".to_string(), script],
-    )
-    .await
+    container
+        .exec_oneshot(vec!["sh".to_string(), "-c".to_string(), script])
+        .await
 }
 
 /// Turn a failed start into something the user can act on.
@@ -604,13 +604,16 @@ fn explain_start_failure(err: &str, log: &str) -> String {
 }
 
 /// Tail of the viewer's own output, for a start that didn't come up.
-async fn read_viewer_log(container_id: &str) -> String {
-    exec_oneshot(
-        container_id,
-        vec!["tail".to_string(), "-n".to_string(), "40".to_string(), VIEWER_LOG.to_string()],
-    )
-    .await
-    .unwrap_or_default()
+async fn read_viewer_log(container: &ContainerTarget) -> String {
+    container
+        .exec_oneshot(vec![
+            "tail".to_string(),
+            "-n".to_string(),
+            "40".to_string(),
+            VIEWER_LOG.to_string(),
+        ])
+        .await
+        .unwrap_or_default()
 }
 
 // ─────────────────────────────────────────────────────────────────────────────
@@ -645,14 +648,17 @@ const MAX_PORT_ATTEMPTS: usize = 3;
 /// this layer, and the pane would then front it. What contains that is
 /// downstream — the host proxy is loopback-only and token-gated, and the pane's
 /// iframe is sandboxed — not this function.
-async fn start_viewer(container_id: &str, cli_entry: &str) -> Result<(u16, String), String> {
+async fn start_viewer(
+    container: &ContainerTarget,
+    cli_entry: &str,
+) -> Result<(u16, String), String> {
     let mut tried: Vec<u16> = Vec::new();
     let mut last: Option<String> = None;
 
     for _ in 0..MAX_PORT_ATTEMPTS {
         // Re-read the listener snapshot each attempt: the port that was free a
         // moment ago is exactly the one we may have just lost.
-        let port = match pick_viewer_port(container_id, &tried).await {
+        let port = match pick_viewer_port(container, &tried).await {
             Ok(p) => p,
             Err(e) => {
                 // Report why the *attempts* failed, not just "nothing free":
@@ -666,21 +672,21 @@ async fn start_viewer(container_id: &str, cli_entry: &str) -> Result<(u16, Strin
         };
         tried.push(port);
 
-        launch_viewer(container_id, cli_entry, port).await?;
+        launch_viewer(container, cli_entry, port).await?;
 
         // Wait for it to actually answer, and learn the entry URL while we're
         // there — see `probe_entry_path` for why that matters. This, not the
         // launcher's stdout, is the readiness signal: verified that the
         // "Listening on …" line is printed only on the very first start.
-        match wait_until_ready(container_id, port).await {
+        match wait_until_ready(container, port).await {
             Ok(path) => return Ok((port, path)),
             Err(e) => {
-                let log = read_viewer_log(container_id).await;
+                let log = read_viewer_log(container).await;
                 // Always kill before retrying: the dashboard is a singleton, so
                 // a launcher that came up on some *other* port would otherwise
                 // make every further attempt a no-op that silently ignores the
                 // port we asked for.
-                let _ = kill_dashboard(container_id, cli_entry).await;
+                let _ = kill_dashboard(container, cli_entry).await;
                 last = Some(explain_start_failure(&e, &log));
             }
         }
@@ -691,10 +697,9 @@ async fn start_viewer(container_id: &str, cli_entry: &str) -> Result<(u16, Strin
 
 /// First port in [`VIEWER_PORTS`] that nothing in the container is listening on
 /// and that this start has not already tried.
-async fn pick_viewer_port(container_id: &str, tried: &[u16]) -> Result<u16, String> {
-    let text = exec_oneshot(
-        container_id,
-        vec![
+async fn pick_viewer_port(container: &ContainerTarget, tried: &[u16]) -> Result<u16, String> {
+    let text = container
+        .exec_oneshot(vec![
             // Absolute path, deliberately, for the same reason the auth bridge
             // uses one: `container/Dockerfile` puts a container-writable
             // directory first on `PATH`, so a bare `cat` is a name the container
@@ -704,10 +709,9 @@ async fn pick_viewer_port(container_id: &str, tried: &[u16]) -> Result<u16, Stri
             "/usr/bin/cat".to_string(),
             "/proc/net/tcp".to_string(),
             "/proc/net/tcp6".to_string(),
-        ],
-    )
-    .await
-    .unwrap_or_default();
+        ])
+        .await
+        .unwrap_or_default();
     let taken = proc_net::parse_loopback_listeners(&text);
     VIEWER_PORTS
         .clone()
@@ -722,10 +726,10 @@ async fn pick_viewer_port(container_id: &str, tried: &[u16]) -> Result<u16, Stri
 }
 
 /// Poll the viewer until it answers, and return the path the pane should load.
-async fn wait_until_ready(container_id: &str, port: u16) -> Result<String, String> {
+async fn wait_until_ready(container: &ContainerTarget, port: u16) -> Result<String, String> {
     let deadline = tokio::time::Instant::now() + READY_TIMEOUT;
     loop {
-        let last = match probe_entry_path(container_id, port).await {
+        let last = match probe_entry_path(container, port).await {
             Ok(path) => return Ok(path),
             Err(e) => e,
         };
@@ -751,7 +755,7 @@ const PROBE_MARKER: &str = "__TRIPLE_C_BV_PATH__";
 /// a redirect — which matters, because a redirect drops the `?token=` the proxy
 /// gate wants and would leave a fresh connection to be authorised with nothing.
 /// A `200` (no redirect) is fine too; then the entry point is just `/`.
-async fn probe_entry_path(container_id: &str, port: u16) -> Result<String, String> {
+async fn probe_entry_path(container: &ContainerTarget, port: u16) -> Result<String, String> {
     // The request is bounded on both sides. Verified: the dashboard answers a
     // bad WebSocket path by holding the socket open forever rather than
     // erroring, so "no reply" is a state this probe has to be able to leave —
@@ -766,10 +770,7 @@ async fn probe_entry_path(container_id: &str, port: u16) -> Result<String, Strin
     );
     let out = tokio::time::timeout(
         PROBE_TIMEOUT * 2,
-        exec_oneshot(
-            container_id,
-            vec!["node".to_string(), "-e".to_string(), script],
-        ),
+        container.exec_oneshot(vec!["node".to_string(), "-e".to_string(), script]),
     )
     .await
     .map_err(|_| "the viewer probe did not return".to_string())??;

app/src-tauri/src/browser_view/page.rs

@@ -37,7 +37,7 @@ use serde::{Deserialize, Serialize};
 use tauri::AppHandle;
 
 use crate::commands::project_commands::emit_progress;
-use crate::docker::exec::exec_oneshot_as;
+use crate::host::ContainerTarget;
 
 use super::detect::PlaywrightDetection;
 
@@ -150,14 +150,14 @@ pub async fn open(
         shell_quote(&script),
         HELPER_LOG
     );
-    exec_oneshot_as(
-        container_id,
-        "claude",
-        vec!["sh".to_string(), "-c".to_string(), launcher],
-        Vec::new(),
-    )
-    .await
-    .map_err(|e| format!("Could not start the browser helper: {}", e))?;
+    ContainerTarget::docker(container_id)
+        .exec_oneshot_as(
+            "claude",
+            vec!["sh".to_string(), "-c".to_string(), launcher],
+            Vec::new(),
+        )
+        .await
+        .map_err(|e| format!("Could not start the browser helper: {}", e))?;
 
     emit_progress(app, project_id, "Waiting for the page to load…");
     wait_until_ready(container_id).await
@@ -189,13 +189,13 @@ pub async fn state(container_id: &str) -> PageState {
         "try{{process.stdout.write(require('fs').readFileSync('{}','utf8'));}}catch(e){{}}",
         STATE_PATH
     );
-    let Ok((out, _)) = exec_oneshot_as(
-        container_id,
-        "claude",
-        vec!["node".to_string(), "-e".to_string(), script],
-        Vec::new(),
-    )
-    .await
+    let Ok((out, _)) = ContainerTarget::docker(container_id)
+        .exec_oneshot_as(
+            "claude",
+            vec!["node".to_string(), "-e".to_string(), script],
+            Vec::new(),
+        )
+        .await
     else {
         return PageState::default();
     };
@@ -209,15 +209,15 @@ async fn write_control(container_id: &str, json: String) -> Result<(), String> {
         "require('fs').writeFileSync('{}',process.argv[1]);",
         CONTROL_PATH
     );
-    exec_oneshot_as(
-        container_id,
-        "claude",
-        vec!["node".to_string(), "-e".to_string(), script, json],
-        Vec::new(),
-    )
-    .await
-    .map(|_| ())
-    .map_err(|e| format!("Could not reach the browser helper: {}", e))
+    ContainerTarget::docker(container_id)
+        .exec_oneshot_as(
+            "claude",
+            vec!["node".to_string(), "-e".to_string(), script, json],
+            Vec::new(),
+        )
+        .await
+        .map(|_| ())
+        .map_err(|e| format!("Could not reach the browser helper: {}", e))
 }
 
 /// Wait for a *running* helper to report the URL we just asked it for.

app/src-tauri/src/commands/auth_token_commands.rs

@@ -76,8 +76,7 @@ use tauri::{AppHandle, Emitter, State};
 use tokio::io::AsyncWriteExt;
 use tokio::sync::{mpsc, oneshot, Mutex};
 
-use crate::docker::container::is_container_running;
-use crate::docker::exec::{create_attached_exec, wait_for_exec_exit, AttachedExec};
+use crate::host::{AttachedExec, ContainerTarget};
 use crate::storage::secure;
 use crate::AppState;
 
@@ -867,7 +866,7 @@ async fn type_code_then_enter<W: tokio::io::AsyncWrite + Unpin>(
 async fn run_setup_token(
     app: &AppHandle,
     project_id: &str,
-    container_id: &str,
+    target: &ContainerTarget,
     mut input_rx: mpsc::UnboundedReceiver<Vec<u8>>,
     mut cancel_rx: oneshot::Receiver<()>,
 ) -> Result<String, String> {
@@ -877,16 +876,16 @@ async fn run_setup_token(
         exec_id,
         mut output,
         mut input,
-    } = create_attached_exec(
-        container_id,
-        vec![
-            "sh".to_string(),
-            "-c".to_string(),
-            SETUP_TOKEN_SCRIPT.to_string(),
-        ],
-        true,
-    )
-    .await?;
+    } = target
+        .attach_exec(
+            vec![
+                "sh".to_string(),
+                "-c".to_string(),
+                SETUP_TOKEN_SCRIPT.to_string(),
+            ],
+            true,
+        )
+        .await?;
 
     let mut stripper = AnsiStripper::default();
     let mut redactor = SecretRedactor::default();
@@ -1041,7 +1040,7 @@ async fn run_setup_token(
     // Falling through to the token parse is right either way — a run that
     // printed a token succeeded whatever Docker says about it — but it is worth
     // saying so rather than silently calling it a clean exit.
-    match wait_for_exec_exit(&exec_id).await {
+    match target.wait_exec_exit(&exec_id).await {
         Some(0) => {}
         Some(code) => {
             return Err(format!(
@@ -1091,13 +1090,13 @@ pub async fn acquire_claude_token(
         .get(&project_id)
         .ok_or_else(|| format!("Project {} not found", project_id))?;
 
-    let container_id = project.container_id.clone().ok_or_else(|| {
+    let target = ContainerTarget::for_project(&project).ok_or_else(|| {
         format!(
             "Project '{}' has no container yet. Start it, then run authentication again.",
             project.name
         )
     })?;
-    if !is_container_running(&container_id).await.unwrap_or(false) {
+    if !target.is_running().await.unwrap_or(false) {
         return Err(format!(
             "The container for '{}' is not running. Start it, then run authentication again.",
             project.name
@@ -1133,8 +1132,7 @@ pub async fn acquire_claude_token(
         "Running `claude setup-token` — sign in at the URL below, then submit the code it gives you.",
     );
 
-    let result =
-        run_setup_token(&app_handle, &project_id, &container_id, input_rx, cancel_rx).await;
+    let result = run_setup_token(&app_handle, &project_id, &target, input_rx, cancel_rx).await;
 
     // Release the flow. Nothing else needs unwinding: this command changes no
     // persisted state until the token itself is stored, which is the point.

app/src-tauri/src/commands/file_commands.rs

@@ -4,14 +4,11 @@ use std::sync::Arc;
 
 use base64::engine::general_purpose::STANDARD as BASE64;
 use base64::Engine as _;
-use bollard::container::{DownloadFromContainerOptions, LogOutput};
-use bollard::exec::{CreateExecOptions, StartExecResults};
 use futures_util::StreamExt;
 use serde::Serialize;
 use tauri::State;
 
-use crate::docker::client::get_docker;
-use crate::docker::exec::{exec_oneshot_as, exec_oneshot_streams_as, OUTPUT_LIMIT_MARKER};
+use crate::host::{ContainerTarget, ExecChunk, ExecSpec, OUTPUT_LIMIT_MARKER};
 use crate::AppState;
 
 #[derive(Debug, PartialEq, Serialize)]
@@ -63,9 +60,7 @@ pub async fn list_container_files(
         .get(&project_id)
         .ok_or_else(|| format!("Project {} not found", project_id))?;
 
-    let container_id = project
-        .container_id
-        .as_ref()
+    let target = ContainerTarget::for_project(&project)
         .ok_or_else(|| "Container not running".to_string())?;
 
     // `exec_oneshot` discards the exit code, which is how a `find` that listed
@@ -78,7 +73,8 @@ pub async fn list_container_files(
     // are the error message, its `-printf` records are the listing, and the
     // parser should never be handed the former.
     let (records, diagnostics, code) =
-        exec_oneshot_streams_as(container_id, "claude", list_argv(&path), Vec::new())
+        target
+            .exec_oneshot_streams_as("claude", list_argv(&path), Vec::new())
             .await
             .map_err(|e| describe_listing_failure(&path, e))?;
 
@@ -156,7 +152,7 @@ fn list_argv(path: &str) -> Vec<String> {
 /// folder can act on.
 ///
 /// One case is worth naming: a directory with more entries than
-/// [`crate::docker::exec::MAX_ONESHOT_OUTPUT`] will hold. Roughly 100k names is
+/// [`crate::host::MAX_ONESHOT_OUTPUT`] will hold. Roughly 100k names is
 /// the point where a `find` record set passes 8 MiB, and what the panel showed
 /// was "Command output exceeded 8388608 bytes and was abandoned" — a true
 /// statement about a buffer, and no help at all about a directory.
@@ -430,7 +426,11 @@ pub(crate) fn validate_container_write_path(what: &str, path: &str) -> Result<()
 /// and the lexical answer stands: failing every write closed would break the
 /// panel outright for a risk the container user does not need this code path to
 /// take.
-async fn resolve_container_dir(container_id: &str, what: &str, dir: &str) -> Result<(), String> {
+async fn resolve_container_dir(
+    target: &ContainerTarget,
+    what: &str,
+    dir: &str,
+) -> Result<(), String> {
     validate_container_write_path(what, dir)?;
 
     // Split streams, not the combined buffer: `realpath`'s answer is a *path*
@@ -438,18 +438,18 @@ async fn resolve_container_dir(container_id: &str, what: &str, dir: &str) -> Res
     // hazard the listing above took apart for `find`. A warning on stderr —
     // and there is one whenever a component is unreadable — used to be spliced
     // into the string this then compared against the write roots.
-    let (stdout, diagnostics, code) = exec_oneshot_streams_as(
-        container_id,
-        "claude",
-        vec![
-            "realpath".to_string(),
-            "-m".to_string(),
-            "--".to_string(),
-            dir.to_string(),
-        ],
-        Vec::new(),
-    )
-    .await?;
+    let (stdout, diagnostics, code) = target
+        .exec_oneshot_streams_as(
+            "claude",
+            vec![
+                "realpath".to_string(),
+                "-m".to_string(),
+                "--".to_string(),
+                dir.to_string(),
+            ],
+            Vec::new(),
+        )
+        .await?;
 
     let resolved = stdout.trim();
     if code != 0 || resolved.is_empty() {
@@ -1188,7 +1188,7 @@ pub(crate) struct FetchedFile {
 
 /// Fetch a single regular file from a container as exact bytes.
 ///
-/// The viewer's read. It deliberately goes through Docker's archive endpoint rather than
+/// The viewer's read. It deliberately goes through the archive endpoint rather than
 /// `exec_oneshot`: that reader runs every chunk through `String::from_utf8_lossy`
 /// and merges stderr into stdout, so it would both corrupt any non-UTF-8 file
 /// and be able to splice diagnostics into what the caller believes is content.
@@ -1202,19 +1202,15 @@ pub(crate) struct FetchedFile {
 /// file — or the whole *directory tree*, since the type check happens after the
 /// read — landed in host RAM twice. This function buffers, so every caller of
 /// it must name a ceiling.
+///
+/// Takes a container id rather than a [`ContainerTarget`] because the file
+/// viewer's commands call it with the id they already hold.
 pub(crate) async fn fetch_container_file(
     container_id: &str,
     container_path: &str,
     max_bytes: u64,
 ) -> Result<FetchedFile, String> {
-    let docker = get_docker()?;
-
-    let mut stream = docker.download_from_container(
-        container_id,
-        Some(DownloadFromContainerOptions {
-            path: container_path.to_string(),
-        }),
-    );
+    let mut stream = ContainerTarget::docker(container_id).download_archive(container_path);
 
     // A tar member is a 512-byte header plus payload padded to 512. 8 KiB of
     // slack past the payload cap guarantees the header and the whole capped
@@ -1297,13 +1293,11 @@ pub async fn read_container_file(
         .get(&project_id)
         .ok_or_else(|| format!("Project {} not found", project_id))?;
 
-    let container_id = project
-        .container_id
-        .as_ref()
+    let target = ContainerTarget::for_project(&project)
         .ok_or_else(|| "Container not running".to_string())?;
 
     let cap = max_bytes.unwrap_or(MAX_READ_BYTES).min(MAX_READ_BYTES);
-    let fetched = fetch_container_file(container_id, &path, cap).await?;
+    let fetched = fetch_container_file(target.id(), &path, cap).await?;
 
     Ok(FileContents {
         contents_base64: BASE64.encode(&fetched.bytes),
@@ -1333,9 +1327,7 @@ pub async fn rename_container_path(
         .get(&project_id)
         .ok_or_else(|| format!("Project {} not found", project_id))?;
 
-    let container_id = project
-        .container_id
-        .as_ref()
+    let target = ContainerTarget::for_project(&project)
         .ok_or_else(|| "Container not running".to_string())?;
 
     // The name is checked by `validate_entry_name`; the path it is applied to
@@ -1349,7 +1341,7 @@ pub async fn rename_container_path(
     // directory component to resolve.
     let parent = parent_dir(&from_path);
     if parent != "/" {
-        resolve_container_dir(container_id, "Item", &parent).await?;
+        resolve_container_dir(&target, "Item", &parent).await?;
     }
 
     let new_name = to_path.trim();
@@ -1364,8 +1356,7 @@ pub async fn rename_container_path(
     // and exits 0 — so `-n` on its own would report a rename that never
     // happened. The existence check is what turns it into an error the user
     // sees; `-n` stays as the belt-and-braces against the race between them.
-    let (_, exists) = exec_oneshot_as(
-        container_id,
+    let (_, exists) = target.exec_oneshot_as(
         "claude",
         vec!["test".to_string(), "-e".to_string(), dest.clone()],
         Vec::new(),
@@ -1375,8 +1366,7 @@ pub async fn rename_container_path(
         return Err(format!("\"{}\" already exists in this folder", new_name));
     }
 
-    let (output, code) = exec_oneshot_as(
-        container_id,
+    let (output, code) = target.exec_oneshot_as(
         "claude",
         vec![
             "mv".to_string(),
@@ -1417,19 +1407,16 @@ pub async fn create_container_directory(
         .get(&project_id)
         .ok_or_else(|| format!("Project {} not found", project_id))?;
 
-    let container_id = project
-        .container_id
-        .as_ref()
+    let target = ContainerTarget::for_project(&project)
         .ok_or_else(|| "Container not running".to_string())?;
 
-    resolve_container_dir(container_id, "Folder", &parent_path).await?;
+    resolve_container_dir(&target, "Folder", &parent_path).await?;
 
     let name = name.trim();
     validate_entry_name(name)?;
     let dest = join_path(&parent_path, name);
 
-    let (output, code) = exec_oneshot_as(
-        container_id,
+    let (output, code) = target.exec_oneshot_as(
         "claude",
         vec!["mkdir".to_string(), "--".to_string(), dest.clone()],
         Vec::new(),
@@ -1459,20 +1446,19 @@ pub(crate) fn not_running_message(action: &str, why: &str) -> String {
 /// Refuse, in a sentence, before a Docker error has to speak for us.
 ///
 /// Both file transfers and the backup run through `docker exec`, which needs a
-/// running container. Without this the failure surfaces as bollard's
+/// running container. Without this the failure surfaces as Docker's
 /// `is not running` wrapped in whatever the caller was doing, and for the
 /// upload it surfaces even less usefully: `resolve_container_dir`'s `realpath`
 /// is the first thing to touch the container, so a stopped project fails inside
 /// path *validation* and reads like the path was the problem.
+///
+/// Takes a container id rather than a [`ContainerTarget`] because the file
+/// viewer's commands call it with the id they already hold.
 pub(crate) async fn require_running(container_id: &str, action: &str) -> Result<(), String> {
-    let docker = get_docker()?;
-    let running = docker
-        .inspect_container(container_id, None)
-        .await
-        .ok()
-        .and_then(|info| info.state)
-        .and_then(|s| s.running)
-        .unwrap_or(false);
+    // An unreachable daemon is an error; an inspect failure (container gone)
+    // reads as "not running" — `is_running`'s contract, and what this did
+    // when it inspected the container itself.
+    let running = ContainerTarget::docker(container_id).is_running().await?;
     if running {
         return Ok(());
     }
@@ -1543,12 +1529,10 @@ pub async fn download_container_file(
         .get(&project_id)
         .ok_or_else(|| format!("Project {} not found", project_id))?;
 
-    let container_id = project
-        .container_id
-        .as_ref()
+    let target = ContainerTarget::for_project(&project)
         .ok_or_else(|| "No container exists for this project yet — start it first".to_string())?;
 
-    require_running(container_id, "saving a file to the host").await?;
+    require_running(target.id(), "saving a file to the host").await?;
 
     let Some(chosen) = pick_save_path(&window, &suggested_save_name(&container_path)).await else {
         // Dismissed. Not an error, and deliberately distinguishable from one:
@@ -1564,8 +1548,6 @@ pub async fn download_container_file(
     // costs. See the note on `pick_save_path` about which ones those are.
     let dest = resolve_host_path(&chosen, HostPathUse::WriteChosenName).await?;
 
-    let docker = get_docker()?;
-
     // `$TC_SRC`, never argv interpolation: the path reaches the shell as an
     // environment value, so a name containing a quote or a `$` is data.
     //
@@ -1627,30 +1609,19 @@ esac
 echo "TC_SIZE=$SZ" >&2
 dd iflag=nonblock bs=64k status=none if="$TC_SRC" || exit 5"#;
 
-    let exec = docker
-        .create_exec(
-            container_id,
-            CreateExecOptions {
-                attach_stdout: Some(true),
-                attach_stderr: Some(true),
-                cmd: Some(vec!["sh".to_string(), "-c".to_string(), script.to_string()]),
-                env: Some(vec![format!("TC_SRC={}", container_path)]),
-                user: Some("claude".to_string()),
-                ..Default::default()
-            },
+    // As `claude`, no TTY, no stdin and no working directory (the image's
+    // default) — the options this exec has always been created with.
+    let exec = target
+        .attach(
+            ExecSpec::new(vec!["sh".to_string(), "-c".to_string(), script.to_string()])
+                .env(vec![format!("TC_SRC={}", container_path)])
+                .working_dir(None)
+                .no_stdin(),
         )
         .await
         .map_err(|e| format!("Failed to start download: {}", e))?;
-
-    let result = docker
-        .start_exec(&exec.id, None)
-        .await
-        .map_err(|e| format!("Failed to start download: {}", e))?;
-
-    let mut output = match result {
-        StartExecResults::Attached { output, .. } => output,
-        StartExecResults::Detached => return Err("Download exec started detached".to_string()),
-    };
+    let exec_id = exec.exec_id;
+    let mut output = exec.output;
 
     use tokio::io::AsyncWriteExt;
     let partial = partial_download_path(&dest)?;
@@ -1696,7 +1667,7 @@ dd iflag=nonblock bs=64k status=none if="$TC_SRC" || exit 5"#;
 
     while let Some(msg) = output.next().await {
         match msg {
-            Ok(LogOutput::StdOut { message }) => {
+            Ok(ExecChunk::StdOut(message)) => {
                 if let Err(e) = writer.write_all(&message).await {
                     stream_err = Some(format!("Failed to write {}: {}", dest.display(), e));
                     break;
@@ -1727,7 +1698,7 @@ dd iflag=nonblock bs=64k status=none if="$TC_SRC" || exit 5"#;
                     }
                 }
             }
-            Ok(LogOutput::StdErr { message }) => {
+            Ok(ExecChunk::StdErr(message)) => {
                 push_capped(&mut stderr_text, &message);
                 if declared.is_none() {
                     declared = parse_declared_size(&stderr_text);
@@ -1760,7 +1731,7 @@ dd iflag=nonblock bs=64k status=none if="$TC_SRC" || exit 5"#;
     // success renames a truncated partial over the file the user already had
     // and reports the byte count as if it were the whole thing. That is the one
     // way this command could destroy data, so silence is failure.
-    let exit_code = crate::docker::exec::wait_for_exec_exit(&exec.id).await;
+    let exit_code = target.wait_exec_exit(&exec_id).await;
     if stream_err.is_none() && exit_code != Some(0) {
         // Framed and clipped, never verbatim.
         //
@@ -1894,7 +1865,7 @@ pub struct UploadOutcome {
 ///   * the destination goes through [`resolve_container_dir`], so it is inside
 ///     [`CONTAINER_WRITE_ROOTS`] both as written and as it resolves;
 ///   * the read, the size ceiling and the descriptor check are
-///     `docker::exec::upload_host_file_with_ids`', unchanged — including
+///     `ContainerTarget::upload_host_file_with_ids`', unchanged — including
 ///     landing the file owned by the container user rather than root.
 ///
 /// The dialog itself is opened from Rust ([`pick_files_to_upload`]), which is
@@ -1911,15 +1882,13 @@ pub async fn upload_files_to_container(
         .get(&project_id)
         .ok_or_else(|| format!("Project {} not found", project_id))?;
 
-    let container_id = project
-        .container_id
-        .as_ref()
+    let target = ContainerTarget::for_project(&project)
         .ok_or_else(|| "No container exists for this project yet — start it first".to_string())?;
 
     // Both checks before the dialog, so a project that cannot receive files
     // says so instead of asking the user to choose some first.
-    require_running(container_id, "uploading files").await?;
-    resolve_container_dir(container_id, "Upload", &container_dir).await?;
+    require_running(target.id(), "uploading files").await?;
+    resolve_container_dir(&target, "Upload", &container_dir).await?;
 
     let Some(picked) = pick_files_to_upload(&window).await else {
         return Ok(None);
@@ -1930,14 +1899,14 @@ pub async fn upload_files_to_container(
     // files; this one is the check that actually guards the extraction. A modal
     // has no time limit, and `resolve_container_dir` answers a question about
     // the container's filesystem — which the container is free to change while
-    // the dialog is open. Without this, `docker::exec`'s doc comment claim that
+    // the dialog is open. Without this, the uploader's doc comment claim that
     // the destination "has already been confirmed" would be true only of a
     // moment that had passed.
-    resolve_container_dir(container_id, "Upload", &container_dir).await?;
+    resolve_container_dir(&target, "Upload", &container_dir).await?;
 
     // Once for the whole selection, not once per file — see
     // `upload_host_file_with_ids`.
-    let ids = crate::docker::exec::container_user_ids(container_id).await;
+    let ids = target.user_ids().await;
 
     let mut outcome = UploadOutcome {
         uploaded: Vec::new(),
@@ -1951,7 +1920,7 @@ pub async fn upload_files_to_container(
                 continue;
             }
         };
-        match upload_one(container_id, &path, &container_dir, ids).await {
+        match upload_one(&target, &path, &container_dir, ids).await {
             Ok(dest) => {
                 log::info!("Uploaded {} into project {} at {}", path, project_id, dest);
                 outcome.uploaded.push(dest);
@@ -1966,7 +1935,7 @@ pub async fn upload_files_to_container(
 /// naming the file, because the caller may be reporting several at once and
 /// "is a folder" on its own does not say which one.
 async fn upload_one(
-    container_id: &str,
+    target: &ContainerTarget,
     host_path: &str,
     container_dir: &str,
     ids: (u64, u64),
@@ -1990,7 +1959,7 @@ async fn upload_one(
     // The ceiling is enforced against the open descriptor inside the uploader;
     // this copy of it exists so the refusal arrives as a sentence instead of
     // after a 300 MB read.
-    use crate::docker::exec::MAX_DROP_BYTES;
+    use crate::host::MAX_DROP_BYTES;
     if meta.len() > MAX_DROP_BYTES {
         return Err(format!(
             "{} is too large to upload ({:.0} MB; limit {} MB). Mount it into the project instead.",
@@ -2000,14 +1969,9 @@ async fn upload_one(
         ));
     }
 
-    crate::docker::exec::upload_host_file_with_ids(
-        container_id,
-        &resolved,
-        container_dir,
-        &name,
-        ids,
-    )
-    .await
+    target
+        .upload_host_file_with_ids(&resolved, container_dir, &name, ids)
+        .await
 }
 
 /// Container-authored diagnostic text, cut down to something safe to quote.
@@ -2274,14 +2238,10 @@ pub async fn download_container_backup(
         .get(&project_id)
         .ok_or_else(|| format!("Project {} not found", project_id))?;
 
-    let container_id = project
-        .container_id
-        .as_ref()
+    let target = ContainerTarget::for_project(&project)
         .ok_or_else(|| "No container exists for this project yet — start it first".to_string())?;
 
-    let docker = get_docker()?;
-
-    require_running(container_id, "backing up").await?;
+    require_running(target.id(), "backing up").await?;
 
     let path = container_path.unwrap_or_else(|| "/workspace".to_string());
     // Read-only source: `tar -C` it, so absoluteness and `..` are what matter.
@@ -2326,33 +2286,22 @@ tar czf - --ignore-failed-read \
 
     let cmd = vec!["sh".to_string(), "-c".to_string(), script.to_string()];
 
-    let exec = docker
-        .create_exec(
-            container_id,
-            CreateExecOptions {
-                attach_stdout: Some(true),
-                attach_stderr: Some(true),
-                cmd: Some(cmd),
-                env: Some(vec![
+    // As `claude`, no TTY, no stdin and no working directory (the image's
+    // default) — the options this exec has always been created with.
+    let exec = target
+        .attach(
+            ExecSpec::new(cmd)
+                .env(vec![
                     "HOME=/home/claude".to_string(),
                     format!("TC_BACKUP_SRC={}", path),
-                ]),
-                user: Some("claude".to_string()),
-                ..Default::default()
-            },
+                ])
+                .working_dir(None)
+                .no_stdin(),
         )
         .await
-        .map_err(|e| format!("Failed to create backup exec: {}", e))?;
-
-    let result = docker
-        .start_exec(&exec.id, None)
-        .await
-        .map_err(|e| format!("Failed to start backup exec: {}", e))?;
-
-    let mut output = match result {
-        StartExecResults::Attached { output, .. } => output,
-        StartExecResults::Detached => return Err("Backup exec started detached".to_string()),
-    };
+        .map_err(|e| format!("Failed to start backup: {}", e))?;
+    let exec_id = exec.exec_id;
+    let mut output = exec.output;
 
     use tokio::io::AsyncWriteExt;
     let partial = partial_download_path(&dest)?;
@@ -2401,14 +2350,14 @@ tar czf - --ignore-failed-read \
 
     while let Some(msg) = output.next().await {
         match msg {
-            Ok(LogOutput::StdOut { message }) => {
+            Ok(ExecChunk::StdOut(message)) => {
                 if let Err(e) = writer.write_all(&message).await {
                     stream_err = Some(format!("Failed to write backup file: {}", e));
                     break;
                 }
                 total += message.len() as u64;
             }
-            Ok(LogOutput::StdErr { message }) => {
+            Ok(ExecChunk::StdErr(message)) => {
                 push_capped(&mut stderr_text, &message);
             }
             Ok(_) => {}
@@ -2430,7 +2379,7 @@ tar czf - --ignore-failed-read \
     // when `total > 0`. Poll until the exec actually reports finished so the
     // exit code is reliably populated; if it can't be determined we fall back to
     // the `total == 0` check below.
-    let exit_code = crate::docker::exec::wait_for_exec_exit(&exec.id).await;
+    let exit_code = target.wait_exec_exit(&exec_id).await;
 
     if stream_err.is_none() && exit_code.is_some_and(|c| c != 0) {
         stream_err = Some(format!(
@@ -3564,10 +3513,11 @@ mod tests {
 
         // `/workspace/escape` is under a write root as a string and is `/etc` as
         // a location.
-        let escaped = resolve_container_dir(&name, "Folder", "/workspace/escape").await;
+        let target = ContainerTarget::docker(name.clone());
+        let escaped = resolve_container_dir(&target, "Folder", "/workspace/escape").await;
         println!("container escape: {:?}", escaped);
         assert!(escaped.is_err(), "a symlink out of /workspace was accepted");
-        resolve_container_dir(&name, "Folder", "/workspace")
+        resolve_container_dir(&target, "Folder", "/workspace")
             .await
             .expect("/workspace itself");
 
@@ -3575,7 +3525,7 @@ mod tests {
         // reporting itself empty — `-H` follows the start point, and only the
         // start point.
         let (records, diagnostics, code) =
-            exec_oneshot_streams_as(&name, "claude", list_argv("/workspace/link"), Vec::new())
+            target.exec_oneshot_streams_as("claude", list_argv("/workspace/link"), Vec::new())
                 .await
                 .unwrap();
         println!("link: code={} diagnostics={:?}", code, diagnostics);
@@ -3588,7 +3538,7 @@ mod tests {
         // The link itself is still *marked* as one in its parent's listing, and
         // still navigable.
         let (records, _, _) =
-            exec_oneshot_streams_as(&name, "claude", list_argv("/workspace"), Vec::new())
+            target.exec_oneshot_streams_as("claude", list_argv("/workspace"), Vec::new())
                 .await
                 .unwrap();
         let parent = parse_find_output("/workspace", &records);
@@ -3607,7 +3557,7 @@ mod tests {
         for path in ["/workspace/broken", "/workspace/loop"] {
             let started = std::time::Instant::now();
             let (records, diagnostics, code) =
-                exec_oneshot_streams_as(&name, "claude", list_argv(path), Vec::new())
+                target.exec_oneshot_streams_as("claude", list_argv(path), Vec::new())
                     .await
                     .unwrap();
             let took = started.elapsed();

app/src-tauri/src/commands/inspect_commands.rs

@@ -12,8 +12,9 @@
 //!
 //! ## Container access
 //!
-//! All work happens inside the container via the existing `docker exec`
-//! plumbing in [`crate::docker::exec`] — no second mechanism is introduced.
+//! All work happens inside the container via the existing exec plumbing,
+//! reached through [`crate::host::ContainerTarget`] — no second mechanism is
+//! introduced.
 //! The heavy lifting (walking dirs, grepping transcripts, parsing JSON with
 //! `jq`) runs *in* the container and only a small JSON summary crosses the
 //! wire, so multi-megabyte transcripts are never streamed back.
@@ -56,14 +57,11 @@
 //! commands fail loudly, since they cannot do anything useful without a
 //! running container.
 
-use bollard::exec::{CreateExecOptions, StartExecOptions};
 use serde::{Deserialize, Serialize};
 use tauri::State;
 
-use crate::docker::client::get_docker;
-use crate::docker::container::is_container_running;
-use crate::docker::exec::{exec_oneshot_env, exec_oneshot_env_status};
 use crate::docker::CONTAINER_HOME;
+use crate::host::{ContainerTarget, ExecSpec};
 use crate::AppState;
 
 /// Newest N session transcripts to inspect. Caps the work done inside the
@@ -192,7 +190,7 @@ pub struct SchedulerNotification {
 // Shared helpers
 // ─────────────────────────────────────────────────────────────────────────────
 
-/// Resolve a project to a *running* container id.
+/// Resolve a project to its *running* container.
 ///
 /// `Ok(None)` means "there is nothing to inspect" — no container recorded, or
 /// the container exists but is stopped. Callers that are read-only turn that
@@ -201,19 +199,19 @@ pub struct SchedulerNotification {
 async fn running_container_for(
     project_id: &str,
     state: &State<'_, AppState>,
-) -> Result<Option<String>, String> {
+) -> Result<Option<ContainerTarget>, String> {
     let project = state
         .projects_store
         .get(project_id)
         .ok_or_else(|| format!("Project {} not found", project_id))?;
 
-    let container_id = match project.container_id {
-        Some(id) => id,
+    let target = match ContainerTarget::for_project(&project) {
+        Some(t) => t,
         None => return Ok(None),
     };
 
-    if is_container_running(&container_id).await.unwrap_or(false) {
-        Ok(Some(container_id))
+    if target.is_running().await.unwrap_or(false) {
+        Ok(Some(target))
     } else {
         Ok(None)
     }
@@ -224,7 +222,7 @@ async fn running_container_for(
 async fn require_running_container(
     project_id: &str,
     state: &State<'_, AppState>,
-) -> Result<String, String> {
+) -> Result<ContainerTarget, String> {
     running_container_for(project_id, state).await?.ok_or_else(|| {
         "Container is not running — start the project first.".to_string()
     })
@@ -240,13 +238,13 @@ fn home_env() -> Vec<String> {
 /// the first line) so the combined stream `exec_oneshot_env` returns is pure
 /// stdout and stays parseable as JSON. A non-zero exit therefore surfaces as
 /// empty output, which the callers treat as "nothing to report".
-async fn run_script(container_id: &str, script: impl Into<String>) -> Result<String, String> {
-    exec_oneshot_env(
-        container_id,
-        vec!["sh".to_string(), "-c".to_string(), script.into()],
-        home_env(),
-    )
-    .await
+async fn run_script(target: &ContainerTarget, script: impl Into<String>) -> Result<String, String> {
+    target
+        .exec_oneshot_env(
+            vec!["sh".to_string(), "-c".to_string(), script.into()],
+            home_env(),
+        )
+        .await
 }
 
 /// Parse script output as JSON, degrading to a default value (and a log line)
@@ -315,11 +313,11 @@ pub(crate) fn validate_session_id(id: &str) -> Result<(), String> {
 /// Run `triple-c-scheduler <args…>` as a bare argv vector — no shell is
 /// involved, so caller-supplied ids cannot be interpreted as shell syntax.
 /// Returns the combined output, erroring with it on a non-zero exit.
-async fn run_scheduler(container_id: &str, args: Vec<String>) -> Result<String, String> {
+async fn run_scheduler(target: &ContainerTarget, args: Vec<String>) -> Result<String, String> {
     let mut cmd = vec!["triple-c-scheduler".to_string()];
     cmd.extend(args);
 
-    let (output, exit_code) = exec_oneshot_env_status(container_id, cmd, home_env()).await?;
+    let (output, exit_code) = target.exec_oneshot_env_status(cmd, home_env()).await?;
     if exit_code != 0 {
         let detail = output.trim();
         return Err(if detail.is_empty() {
@@ -395,8 +393,8 @@ pub async fn list_claude_sessions(
     project_id: String,
     state: State<'_, AppState>,
 ) -> Result<Vec<ClaudeSession>, String> {
-    let container_id = match running_container_for(&project_id, &state).await? {
-        Some(id) => id,
+    let target = match running_container_for(&project_id, &state).await? {
+        Some(t) => t,
         None => return Ok(Vec::new()),
     };
 
@@ -404,7 +402,7 @@ pub async fn list_claude_sessions(
     // a const usize — never from the caller.
     let script = SESSIONS_SCRIPT.replace("__MAX__", &MAX_SESSIONS.to_string());
 
-    let raw = run_script(&container_id, script).await?;
+    let raw = run_script(&target, script).await?;
     let sessions: Vec<RawSession> = parse_or_default(&raw, "session list");
 
     Ok(sessions
@@ -566,12 +564,12 @@ pub async fn list_container_capabilities(
     project_id: String,
     state: State<'_, AppState>,
 ) -> Result<ContainerCapabilities, String> {
-    let container_id = match running_container_for(&project_id, &state).await? {
-        Some(id) => id,
+    let target = match running_container_for(&project_id, &state).await? {
+        Some(t) => t,
         None => return Ok(ContainerCapabilities::default()),
     };
 
-    let raw = run_script(&container_id, CAPABILITIES_SCRIPT).await?;
+    let raw = run_script(&target, CAPABILITIES_SCRIPT).await?;
     Ok(parse_or_default(&raw, "container capabilities"))
 }
 
@@ -681,12 +679,12 @@ pub async fn list_scheduled_tasks(
     project_id: String,
     state: State<'_, AppState>,
 ) -> Result<Vec<ScheduledTask>, String> {
-    let container_id = match running_container_for(&project_id, &state).await? {
-        Some(id) => id,
+    let target = match running_container_for(&project_id, &state).await? {
+        Some(t) => t,
         None => return Ok(Vec::new()),
     };
 
-    let raw = run_script(&container_id, SCHEDULER_LIST_SCRIPT).await?;
+    let raw = run_script(&target, SCHEDULER_LIST_SCRIPT).await?;
     let tasks: Vec<RawScheduledTask> = parse_or_default(&raw, "scheduled tasks");
 
     Ok(tasks
@@ -731,13 +729,13 @@ pub async fn get_scheduled_task_log(
     // Clamped, and an integer by type — cannot carry shell syntax.
     let tail = tail_lines.unwrap_or(200).clamp(1, 5000);
 
-    let container_id = match running_container_for(&project_id, &state).await? {
-        Some(id) => id,
+    let target = match running_container_for(&project_id, &state).await? {
+        Some(t) => t,
         None => return Ok(String::new()),
     };
 
     run_scheduler(
-        &container_id,
+        &target,
         vec![
             "logs".to_string(),
             "--id".to_string(),
@@ -756,15 +754,15 @@ pub async fn get_scheduler_notifications(
     project_id: String,
     state: State<'_, AppState>,
 ) -> Result<Vec<SchedulerNotification>, String> {
-    let container_id = match running_container_for(&project_id, &state).await? {
-        Some(id) => id,
+    let target = match running_container_for(&project_id, &state).await? {
+        Some(t) => t,
         None => return Ok(Vec::new()),
     };
 
     let script =
         SCHEDULER_NOTIFICATIONS_SCRIPT.replace("__MAX__", &MAX_NOTIFICATIONS.to_string());
 
-    let raw = run_script(&container_id, script).await?;
+    let raw = run_script(&target, script).await?;
     let notifications: Vec<RawNotification> = parse_or_default(&raw, "scheduler notifications");
 
     Ok(notifications
@@ -1140,9 +1138,9 @@ pub async fn add_scheduled_task(
         &schedule,
         working_dir.as_deref(),
     )?;
-    let container_id = require_running_container(&project_id, &state).await?;
+    let target = require_running_container(&project_id, &state).await?;
 
-    let output = run_scheduler(&container_id, input.add_args()).await?;
+    let output = run_scheduler(&target, input.add_args()).await?;
     let task_id = parse_created_task_id(&output).ok_or_else(|| {
         format!(
             "The scheduler did not report a task id. Its output was: {}",
@@ -1200,9 +1198,9 @@ pub async fn update_scheduled_task(
         &schedule,
         working_dir.as_deref(),
     )?;
-    let container_id = require_running_container(&project_id, &state).await?;
+    let target = require_running_container(&project_id, &state).await?;
 
-    let output = run_scheduler(&container_id, input.add_args()).await?;
+    let output = run_scheduler(&target, input.add_args()).await?;
     let new_id = parse_created_task_id(&output).ok_or_else(|| {
         format!(
             "The scheduler did not report a task id, so the original task was left in place. Its output was: {}",
@@ -1211,7 +1209,7 @@ pub async fn update_scheduled_task(
     })?;
 
     run_scheduler(
-        &container_id,
+        &target,
         vec!["remove".to_string(), "--id".to_string(), task_id.clone()],
     )
     .await
@@ -1224,7 +1222,7 @@ pub async fn update_scheduled_task(
 
     if enabled == Some(false) {
         if let Err(e) = run_scheduler(
-            &container_id,
+            &target,
             vec!["disable".to_string(), "--id".to_string(), new_id.clone()],
         )
         .await
@@ -1253,11 +1251,11 @@ pub async fn set_scheduled_task_enabled(
     state: State<'_, AppState>,
 ) -> Result<String, String> {
     validate_task_id(&task_id)?;
-    let container_id = require_running_container(&project_id, &state).await?;
+    let target = require_running_container(&project_id, &state).await?;
 
     let subcommand = if enabled { "enable" } else { "disable" };
     let output = run_scheduler(
-        &container_id,
+        &target,
         vec![subcommand.to_string(), "--id".to_string(), task_id],
     )
     .await?;
@@ -1277,39 +1275,20 @@ pub async fn run_scheduled_task_now(
     state: State<'_, AppState>,
 ) -> Result<String, String> {
     validate_task_id(&task_id)?;
-    let container_id = require_running_container(&project_id, &state).await?;
+    let target = require_running_container(&project_id, &state).await?;
 
-    let docker = get_docker()?;
-    let exec = docker
-        .create_exec(
-            &container_id,
-            CreateExecOptions {
-                attach_stdout: Some(false),
-                attach_stderr: Some(false),
-                // Argv vector — no shell, so `task_id` is inert as data.
-                cmd: Some(vec![
-                    "triple-c-scheduler".to_string(),
-                    "run".to_string(),
-                    "--id".to_string(),
-                    task_id.clone(),
-                ]),
-                env: Some(home_env()),
-                user: Some("claude".to_string()),
-                working_dir: Some("/workspace".to_string()),
-                ..Default::default()
-            },
-        )
-        .await
-        .map_err(|e| format!("Failed to create exec: {}", e))?;
-
-    docker
-        .start_exec(
-            &exec.id,
-            Some(StartExecOptions {
-                detach: true,
-                ..Default::default()
-            }),
-        )
+    // Argv vector — no shell, so `task_id` is inert as data. Stdin, stdout and
+    // stderr are all left unattached; the exec is started detached.
+    let spec = ExecSpec::new(vec![
+        "triple-c-scheduler".to_string(),
+        "run".to_string(),
+        "--id".to_string(),
+        task_id.clone(),
+    ])
+    .env(home_env())
+    .no_stdin();
+    let exec_id = target
+        .exec_detached(spec)
         .await
         .map_err(|e| format!("Failed to start task: {}", e))?;
 
@@ -1317,7 +1296,7 @@ pub async fn run_scheduled_task_now(
         "Triggered scheduler task {} in project {} (detached exec {})",
         task_id,
         project_id,
-        exec.id
+        exec_id
     );
     Ok(format!("Task {} started.", task_id))
 }
@@ -1330,10 +1309,10 @@ pub async fn remove_scheduled_task(
     state: State<'_, AppState>,
 ) -> Result<String, String> {
     validate_task_id(&task_id)?;
-    let container_id = require_running_container(&project_id, &state).await?;
+    let target = require_running_container(&project_id, &state).await?;
 
     let output = run_scheduler(
-        &container_id,
+        &target,
         vec!["remove".to_string(), "--id".to_string(), task_id],
     )
     .await?;
@@ -1346,9 +1325,9 @@ pub async fn clear_scheduler_notifications(
     project_id: String,
     state: State<'_, AppState>,
 ) -> Result<(), String> {
-    let container_id = require_running_container(&project_id, &state).await?;
+    let target = require_running_container(&project_id, &state).await?;
     run_scheduler(
-        &container_id,
+        &target,
         vec!["notifications".to_string(), "--clear".to_string()],
     )
     .await?;

app/src-tauri/src/commands/marketplace_commands.rs

@@ -7,7 +7,7 @@ use std::collections::{BTreeMap, HashSet};
 use tauri::{AppHandle, Emitter, State};
 use tokio::sync::oneshot;
 
-use crate::docker::container::is_container_running;
+use crate::host::ContainerTarget;
 use crate::marketplace::{self as mk, auth, diff, gh_login, git, MarketplaceManager};
 use crate::models::marketplace::{
     is_valid_commit, is_valid_item_key, AccountMethod, FileDiff, InstallScope, ItemUpdate,
@@ -944,8 +944,8 @@ pub async fn apply_marketplace_now(
     };
     let mut results = Vec::new();
     for p in projects {
-        let running = match &p.container_id {
-            Some(cid) => is_container_running(cid).await.unwrap_or(false),
+        let running = match ContainerTarget::for_project(&p) {
+            Some(target) => target.is_running().await.unwrap_or(false),
             None => false,
         };
         if !running {
@@ -1051,13 +1051,13 @@ pub async fn start_marketplace_gh_container_login(
         return Err("Signing in through a container needs a host name without a port.".to_string());
     }
     let project = find_project(&state, &project_id)?;
-    let container_id = project.container_id.clone().ok_or_else(|| {
+    let target = ContainerTarget::for_project(&project).ok_or_else(|| {
         format!(
             "\"{}\" has no container yet. Start it, then try again.",
             project.name
         )
     })?;
-    if !is_container_running(&container_id).await.unwrap_or(false) {
+    if !target.is_running().await.unwrap_or(false) {
         return Err(format!(
             "\"{}\" is not running. Start it, then try again.",
             project.name
@@ -1070,7 +1070,7 @@ pub async fn start_marketplace_gh_container_login(
     }
     let account_id = uuid::Uuid::new_v4().to_string();
     let result =
-        gh_login::run_gh_container_login(&app_handle, &account_id, &container_id, &host, rx).await;
+        gh_login::run_gh_container_login(&app_handle, &account_id, &target, &host, rx).await;
     // `rx` is gone now, so this frees our slot and never a newer login's.
     state.marketplace.release_gh_login().await;
     let token = result?;

app/src-tauri/src/commands/migration_commands.rs

@@ -1860,7 +1860,7 @@ async fn stage_payload(
     project_id: &str,
     verbatim: &[String],
 ) -> Result<String, String> {
-    use bollard::container::LogOutput;
+    use crate::host::ExecChunk;
     use futures_util::StreamExt;
     use tokio::io::AsyncWriteExt;
 
@@ -1913,14 +1913,14 @@ async fn stage_payload(
 
     while let Some(msg) = output.next().await {
         match msg {
-            Ok(LogOutput::StdOut { message }) => {
+            Ok(ExecChunk::StdOut(message)) => {
                 if let Err(e) = writer.write_all(&message).await {
                     stream_err = Some(format!("Failed to write the staging file: {}", e));
                     break;
                 }
                 total += message.len() as u64;
             }
-            Ok(LogOutput::StdErr { message }) => {
+            Ok(ExecChunk::StdErr(message)) => {
                 stderr_text.push_str(&String::from_utf8_lossy(&message));
             }
             Ok(_) => {}
@@ -1979,7 +1979,7 @@ async fn stage_payload(
 /// anything already present in the base, so collisions should be rare either
 /// way.)
 async fn restore_payload(container_id: &str, host_path: &str) -> Result<(), String> {
-    use bollard::container::LogOutput;
+    use crate::host::ExecChunk;
     use futures_util::StreamExt;
     use tokio::io::{AsyncReadExt, AsyncWriteExt};
 
@@ -2007,7 +2007,7 @@ async fn restore_payload(container_id: &str, host_path: &str) -> Result<(), Stri
         let mut text = String::new();
         while let Some(msg) = output.next().await {
             match msg {
-                Ok(LogOutput::StdErr { message }) | Ok(LogOutput::StdOut { message }) => {
+                Ok(ExecChunk::StdErr(message)) | Ok(ExecChunk::StdOut(message)) => {
                     text.push_str(&String::from_utf8_lossy(&message))
                 }
                 Ok(_) => {}

app/src-tauri/src/commands/terminal_commands.rs

@@ -1,6 +1,7 @@
 use tauri::{AppHandle, Emitter, State};
 
 use crate::commands::aws_commands;
+use crate::host::ContainerTarget;
 use crate::models::{Backend, BedrockAuthMethod, Project};
 use crate::AppState;
 
@@ -159,9 +160,7 @@ pub async fn open_terminal_session(
         .get(&project_id)
         .ok_or_else(|| format!("Project {} not found", project_id))?;
 
-    let container_id = project
-        .container_id
-        .as_ref()
+    let target = ContainerTarget::for_project(&project)
         .ok_or_else(|| "Container not running".to_string())?;
 
     if let Some(id) = resume_session_id.as_deref() {
@@ -189,7 +188,7 @@ pub async fn open_terminal_session(
     state
         .exec_manager
         .create_session(
-            container_id,
+            &target,
             &session_id,
             cmd,
             move |data| {
@@ -240,7 +239,7 @@ pub async fn paste_image_to_terminal(
     image_data: Vec<u8>,
     state: State<'_, AppState>,
 ) -> Result<String, String> {
-    let container_id = state.exec_manager.get_container_id(&session_id).await?;
+    let target = state.exec_manager.get_target(&session_id).await?;
 
     let timestamp = std::time::SystemTime::now()
         .duration_since(std::time::UNIX_EPOCH)
@@ -250,7 +249,7 @@ pub async fn paste_image_to_terminal(
 
     state
         .exec_manager
-        .write_file_to_container(&container_id, &file_name, &image_data)
+        .write_file_to_container(&target, &file_name, &image_data)
         .await
 }
 
@@ -283,7 +282,7 @@ pub async fn upload_host_file_to_terminal(
     let base = crate::commands::file_commands::host_upload_name(&host_path)?;
     let host_path = crate::commands::file_commands::resolve_host_read_path(&host_path).await?;
 
-    let container_id = state.exec_manager.get_container_id(&session_id).await?;
+    let target = state.exec_manager.get_target(&session_id).await?;
 
     let meta = tokio::fs::metadata(&host_path)
         .await
@@ -313,7 +312,7 @@ pub async fn upload_host_file_to_terminal(
     // with the code that does the reading, which re-applies it to the open
     // descriptor — this check is here only so the refusal reads like a sentence
     // instead of arriving after a 300 MB read.
-    use crate::docker::exec::MAX_DROP_BYTES;
+    use crate::host::MAX_DROP_BYTES;
     if meta.len() > MAX_DROP_BYTES {
         return Err(format!(
             "File too large to drop into the terminal ({:.0} MB; limit {} MB). Mount it into the project instead.",
@@ -326,20 +325,18 @@ pub async fn upload_host_file_to_terminal(
 
     // Ensure the destination directory exists rather than relying on Docker's
     // archive extractor to create the parent for the uploaded tar entry.
-    crate::docker::exec::exec_oneshot(
-        &container_id,
-        vec!["mkdir".to_string(), "-p".to_string(), "/tmp/triple-c-drops".to_string()],
-    )
-    .await?;
+    target
+        .exec_oneshot(vec![
+            "mkdir".to_string(),
+            "-p".to_string(),
+            "/tmp/triple-c-drops".to_string(),
+        ])
+        .await?;
 
     let file_name = format!("triple-c-drops/{}", base);
-    crate::docker::exec::upload_host_file_to_container(
-        &container_id,
-        &host_path,
-        "/tmp",
-        &file_name,
-    )
-    .await
+    target
+        .upload_host_file(&host_path, "/tmp", &file_name)
+        .await
 }
 
 #[tauri::command]
@@ -347,8 +344,8 @@ pub async fn start_audio_bridge(
     session_id: String,
     state: State<'_, AppState>,
 ) -> Result<(), String> {
-    // Get container_id from the terminal session
-    let container_id = state.exec_manager.get_container_id(&session_id).await?;
+    // Get the container from the terminal session
+    let target = state.exec_manager.get_target(&session_id).await?;
 
     // Create audio bridge exec session with ID "audio-{session_id}"
     // The loop handles reconnection when the FIFO reader (fake rec) is killed and restarted
@@ -362,7 +359,7 @@ pub async fn start_audio_bridge(
     state
         .exec_manager
         .create_session_with_tty(
-            &container_id,
+            &target,
             &audio_session_id,
             cmd,
             false,

app/src-tauri/src/docker/exec.rs

@@ -1,58 +1,44 @@
 use bollard::container::{LogOutput, UploadToContainerOptions};
 use bollard::exec::{CreateExecOptions, ResizeExecOptions, StartExecResults};
-use futures_util::{Stream, StreamExt};
-use std::collections::HashMap;
-use std::pin::Pin;
-use std::sync::Arc;
-use tokio::io::{AsyncWrite, AsyncWriteExt};
-use tokio::sync::{mpsc, Mutex};
+use futures_util::StreamExt;
 
 use super::client::get_docker;
+use crate::host::{ExecChunk, ExecSpec};
 
-/// A `docker exec` that has been created and started with stdin/stdout/stderr
-/// attached — the raw duplex halves, before any policy about what to do with
-/// them.
-///
-/// This is the single place in the codebase that knows how to open an attached
-/// exec. Both consumers are built on it:
-///   * [`ExecSessionManager`] — interactive terminals and the audio bridge,
-///     which pump bytes through mpsc channels and a callback.
-///   * `auth_bridge` — per-connection `socat` tunnels, which pump bytes
-///     straight between a host TCP socket and these halves.
-///
-/// With `tty = false` the output stream is demultiplexed by Docker, so the
-/// consumer can tell [`LogOutput::StdOut`] from [`LogOutput::StdErr`]. That
-/// distinction matters for the auth bridge: `socat`'s diagnostics must not be
-/// spliced into the proxied byte stream.
-pub struct AttachedExec {
-    pub exec_id: String,
-    pub output: Pin<Box<dyn Stream<Item = Result<LogOutput, bollard::errors::Error>> + Send>>,
-    pub input: Pin<Box<dyn AsyncWrite + Send>>,
-}
+// `AttachedExec` lives in `host` now (host-neutral output chunks); this
+// module's job is to produce one from Docker. Its consumers are
+// `host::sessions::ExecSessionManager` (terminals, audio bridge) and the auth
+// bridge's per-connection `socat` tunnels, both through `host::ContainerTarget`.
+// With `tty = false` Docker demultiplexes stdout from stderr, which the auth
+// bridge relies on: `socat`'s diagnostics must not be spliced into the proxied
+// byte stream.
+pub use crate::host::AttachedExec;
 
-/// Create and start an exec with stdin + stdout + stderr attached, returning the
-/// raw duplex halves. Runs as `claude` in `/workspace`, like every other exec
-/// this app opens.
-pub async fn create_attached_exec(
-    container_id: &str,
-    cmd: Vec<String>,
-    tty: bool,
-) -> Result<AttachedExec, String> {
-    create_attached_exec_as(container_id, cmd, tty, "claude", "/workspace").await
-}
-
-/// [`create_attached_exec`] with the user and working directory spelled out.
+/// An attached exec with the user and working directory spelled out.
 ///
-/// Only base-image migration needs this: replaying `apt` and unpacking a
-/// payload tar at `/` have to run as **root**, and every other caller wants the
-/// `claude` / `/workspace` defaults that [`create_attached_exec`] supplies. It
-/// stays the single place an attached exec is opened.
+/// Only base-image migration calls this directly: replaying `apt` and unpacking
+/// a payload tar at `/` have to run as **root**. Everything else goes through
+/// `host::ContainerTarget::attach`.
 pub async fn create_attached_exec_as(
     container_id: &str,
     cmd: Vec<String>,
     tty: bool,
     user: &str,
     working_dir: &str,
+) -> Result<AttachedExec, String> {
+    let spec = ExecSpec::new(cmd)
+        .tty(tty)
+        .user(user)
+        .working_dir(Some(working_dir));
+    create_attached_exec_spec(container_id, &spec).await
+}
+
+/// The single place an attached exec is opened on Docker. Everything else —
+/// [`create_attached_exec_as`] and `host::ContainerTarget::attach` — is a thin
+/// wrapper over this.
+pub async fn create_attached_exec_spec(
+    container_id: &str,
+    spec: &ExecSpec,
 ) -> Result<AttachedExec, String> {
     let docker = get_docker()?;
 
@@ -60,13 +46,14 @@ pub async fn create_attached_exec_as(
         .create_exec(
             container_id,
             CreateExecOptions {
-                attach_stdin: Some(true),
+                attach_stdin: Some(spec.attach_stdin),
                 attach_stdout: Some(true),
                 attach_stderr: Some(true),
-                tty: Some(tty),
-                cmd: Some(cmd),
-                user: Some(user.to_string()),
-                working_dir: Some(working_dir.to_string()),
+                tty: Some(spec.tty),
+                cmd: Some(spec.cmd.clone()),
+                env: if spec.env.is_empty() { None } else { Some(spec.env.clone()) },
+                user: Some(spec.user.clone()),
+                working_dir: spec.working_dir.clone(),
                 ..Default::default()
             },
         )
@@ -82,244 +69,87 @@ pub async fn create_attached_exec_as(
     {
         StartExecResults::Attached { output, input } => Ok(AttachedExec {
             exec_id,
-            output,
+            output: Box::pin(output.map(|r| {
+                r.map(log_output_to_chunk)
+                    .map_err(|e| e.to_string())
+            })),
             input,
         }),
         StartExecResults::Detached => Err("Exec started in detached mode".to_string()),
     }
 }
 
-pub struct ExecSession {
-    pub exec_id: String,
-    pub container_id: String,
-    pub input_tx: mpsc::UnboundedSender<Vec<u8>>,
-    shutdown_tx: mpsc::Sender<()>,
-}
-
-impl ExecSession {
-    pub async fn send_input(&self, data: Vec<u8>) -> Result<(), String> {
-        self.input_tx
-            .send(data)
-            .map_err(|e| format!("Failed to send input: {}", e))
-    }
-
-    #[allow(dead_code)]
-    pub async fn resize(&self, cols: u16, rows: u16) -> Result<(), String> {
-        let docker = get_docker()?;
-        docker
-            .resize_exec(
-                &self.exec_id,
-                ResizeExecOptions {
-                    width: cols,
-                    height: rows,
-                },
-            )
-            .await
-            .map_err(|e| format!("Failed to resize exec: {}", e))
-    }
-
-    pub fn shutdown(&self) {
-        let _ = self.shutdown_tx.try_send(());
+/// bollard's `LogOutput` → the host-neutral [`ExecChunk`]. `Console` is what
+/// Docker calls a TTY stream; it has no stderr, so it is stdout.
+pub fn log_output_to_chunk(o: LogOutput) -> ExecChunk {
+    match o {
+        LogOutput::StdOut { message } | LogOutput::Console { message } => ExecChunk::StdOut(message),
+        LogOutput::StdErr { message } => ExecChunk::StdErr(message),
+        LogOutput::StdIn { message } => ExecChunk::Other(message),
     }
 }
 
-pub struct ExecSessionManager {
-    sessions: Arc<Mutex<HashMap<String, ExecSession>>>,
+/// Start a command with nothing attached and return its exec id without
+/// waiting for it.
+pub async fn exec_detached(container_id: &str, spec: &ExecSpec) -> Result<String, String> {
+    let docker = get_docker()?;
+    let exec = docker
+        .create_exec(
+            container_id,
+            CreateExecOptions {
+                attach_stdout: Some(false),
+                attach_stderr: Some(false),
+                tty: Some(spec.tty),
+                cmd: Some(spec.cmd.clone()),
+                env: if spec.env.is_empty() { None } else { Some(spec.env.clone()) },
+                user: Some(spec.user.clone()),
+                working_dir: spec.working_dir.clone(),
+                ..Default::default()
+            },
+        )
+        .await
+        .map_err(|e| format!("Failed to create exec: {}", e))?;
+    docker
+        .start_exec(
+            &exec.id,
+            Some(bollard::exec::StartExecOptions {
+                detach: true,
+                ..Default::default()
+            }),
+        )
+        .await
+        .map_err(|e| format!("Failed to start exec: {}", e))?;
+    Ok(exec.id)
 }
 
-impl ExecSessionManager {
-    pub fn new() -> Self {
-        Self {
-            sessions: Arc::new(Mutex::new(HashMap::new())),
-        }
-    }
-
-    pub async fn create_session<F>(
-        &self,
-        container_id: &str,
-        session_id: &str,
-        cmd: Vec<String>,
-        on_output: F,
-        on_exit: Box<dyn FnOnce() + Send>,
-    ) -> Result<(), String>
-    where
-        F: Fn(Vec<u8>) + Send + 'static,
-    {
-        self.create_session_with_tty(container_id, session_id, cmd, true, on_output, on_exit)
-            .await
-    }
-
-    pub async fn create_session_with_tty<F>(
-        &self,
-        container_id: &str,
-        session_id: &str,
-        cmd: Vec<String>,
-        tty: bool,
-        on_output: F,
-        on_exit: Box<dyn FnOnce() + Send>,
-    ) -> Result<(), String>
-    where
-        F: Fn(Vec<u8>) + Send + 'static,
-    {
-        let AttachedExec {
+pub async fn resize_exec(exec_id: &str, cols: u16, rows: u16) -> Result<(), String> {
+    let docker = get_docker()?;
+    docker
+        .resize_exec(
             exec_id,
-            mut output,
-            mut input,
-        } = create_attached_exec(container_id, cmd, tty).await?;
+            ResizeExecOptions {
+                width: cols,
+                height: rows,
+            },
+        )
+        .await
+        .map_err(|e| format!("Failed to resize exec: {}", e))
+}
 
-        let (input_tx, mut input_rx) = mpsc::unbounded_channel::<Vec<u8>>();
-        let (shutdown_tx, mut shutdown_rx) = mpsc::channel::<()>(1);
-
-        // Output reader task
-        let session_id_clone = session_id.to_string();
-        let shutdown_tx_clone = shutdown_tx.clone();
-        tokio::spawn(async move {
-            loop {
-                tokio::select! {
-                    msg = output.next() => {
-                        match msg {
-                            Some(Ok(output)) => {
-                                on_output(output.into_bytes().to_vec());
-                            }
-                            Some(Err(e)) => {
-                                log::error!("Exec output error for {}: {}", session_id_clone, e);
-                                break;
-                            }
-                            None => {
-                                log::info!("Exec output stream ended for {}", session_id_clone);
-                                break;
-                            }
-                        }
-                    }
-                    _ = shutdown_rx.recv() => {
-                        log::info!("Exec session {} shutting down", session_id_clone);
-                        break;
-                    }
-                }
-            }
-            on_exit();
-            let _ = shutdown_tx_clone;
-        });
-
-        // Input writer task
-        tokio::spawn(async move {
-            while let Some(data) = input_rx.recv().await {
-                if let Err(e) = input.write_all(&data).await {
-                    log::error!("Failed to write to exec stdin: {}", e);
-                    break;
-                }
-            }
-        });
-
-        let session = ExecSession {
-            exec_id,
-            container_id: container_id.to_string(),
-            input_tx,
-            shutdown_tx,
-        };
-
-        self.sessions
-            .lock()
-            .await
-            .insert(session_id.to_string(), session);
-
-        Ok(())
-    }
-
-    pub async fn send_input(&self, session_id: &str, data: Vec<u8>) -> Result<(), String> {
-        let sessions = self.sessions.lock().await;
-        let session = sessions
-            .get(session_id)
-            .ok_or_else(|| format!("Session {} not found", session_id))?;
-        session.send_input(data).await
-    }
-
-    pub async fn resize(&self, session_id: &str, cols: u16, rows: u16) -> Result<(), String> {
-        // Clone the exec_id under the lock, then drop the lock before the
-        // async Docker API call to avoid holding the mutex across await.
-        let exec_id = {
-            let sessions = self.sessions.lock().await;
-            let session = sessions
-                .get(session_id)
-                .ok_or_else(|| format!("Session {} not found", session_id))?;
-            session.exec_id.clone()
-        };
-        let docker = get_docker()?;
-        docker
-            .resize_exec(
-                &exec_id,
-                ResizeExecOptions {
-                    width: cols,
-                    height: rows,
-                },
-            )
-            .await
-            .map_err(|e| format!("Failed to resize exec: {}", e))
-    }
-
-    pub async fn close_session(&self, session_id: &str) {
-        let mut sessions = self.sessions.lock().await;
-        if let Some(session) = sessions.remove(session_id) {
-            session.shutdown();
-        }
-    }
-
-    pub async fn close_sessions_for_container(&self, container_id: &str) {
-        let mut sessions = self.sessions.lock().await;
-        let ids_to_close: Vec<String> = sessions
-            .iter()
-            .filter(|(_, s)| s.container_id == container_id)
-            .map(|(id, _)| id.clone())
-            .collect();
-        for id in ids_to_close {
-            if let Some(session) = sessions.remove(&id) {
-                session.shutdown();
-            }
-        }
-    }
-
-    pub async fn close_all_sessions(&self) {
-        let mut sessions = self.sessions.lock().await;
-        for (_, session) in sessions.drain() {
-            session.shutdown();
-        }
-    }
-
-    pub async fn get_container_id(&self, session_id: &str) -> Result<String, String> {
-        let sessions = self.sessions.lock().await;
-        let session = sessions
-            .get(session_id)
-            .ok_or_else(|| format!("Session {} not found", session_id))?;
-        Ok(session.container_id.clone())
-    }
-
-    pub async fn write_file_to_container(
-        &self,
-        container_id: &str,
-        file_name: &str,
-        data: &[u8],
-    ) -> Result<String, String> {
-        let docker = get_docker()?;
-
-        // Owned by the container user, stamped now: a default tar header would
-        // land it as root:root/1970 and Claude Code could not rewrite it.
-        let (uid, gid) = container_user_ids(container_id).await;
-        let tar_buf = build_single_file_tar(file_name, data, 0o644, uid, gid, now_epoch_secs())?;
-
-        docker
-            .upload_to_container(
-                container_id,
-                Some(UploadToContainerOptions {
-                    path: "/tmp".to_string(),
-                    ..Default::default()
-                }),
-                tar_buf.into(),
-            )
-            .await
-            .map_err(|e| format!("Failed to upload file to container: {}", e))?;
-
-        Ok(format!("/tmp/{}", file_name))
-    }
+/// Docker's archive API: `path` as a tar stream. Errors are stringified so the
+/// stream is host-neutral.
+pub fn download_archive(container_id: &str, path: &str) -> crate::host::ArchiveStream {
+    let docker = match get_docker() {
+        Ok(d) => d,
+        Err(e) => return Box::pin(futures_util::stream::once(async move { Err(e) })),
+    };
+    let stream = docker.download_from_container(
+        container_id,
+        Some(bollard::container::DownloadFromContainerOptions {
+            path: path.to_string(),
+        }),
+    );
+    Box::pin(stream.map(|r| r.map_err(|e| e.to_string())))
 }
 
 /// Ceiling on one host file packed into a container upload.
@@ -444,14 +274,22 @@ pub async fn upload_bytes_to_container(
     file_name: &str,
     data: &[u8],
     mode: u32,
+) -> Result<String, String> {
+    upload_bytes_with_ids(container_id, dest_dir, file_name, data, mode, (0, 0)).await
+}
+
+/// [`upload_bytes_to_container`] with the tar header's owner set, stamped now.
+pub async fn upload_bytes_with_ids(
+    container_id: &str,
+    dest_dir: &str,
+    file_name: &str,
+    data: &[u8],
+    mode: u32,
+    (uid, gid): (u64, u64),
 ) -> Result<String, String> {
     let docker = get_docker()?;
 
-    // Root-owned on purpose: migration's `tar -T` list is read back as root,
-    // and the marketplace sync uploads into a `claude`-owned directory it
-    // prepares first, so `claude` can still read and delete the files. The
-    // mtime still gets stamped so the file doesn't read as 1970.
-    let tar_buf = build_single_file_tar(file_name, data, mode, 0, 0, now_epoch_secs())?;
+    let tar_buf = build_single_file_tar(file_name, data, mode, uid, gid, now_epoch_secs())?;
 
     docker
         .upload_to_container(

app/src-tauri/src/file_viewer/poll.rs

@@ -7,7 +7,7 @@
 
 use serde::Serialize;
 
-use crate::docker::exec::exec_oneshot_streams_as;
+use crate::host::ContainerTarget;
 
 #[derive(Clone, Debug, Serialize, PartialEq, Eq)]
 pub struct ViewerPoll {
@@ -48,8 +48,9 @@ pub async fn poll_file(container_id: &str, container_path: &str) -> Result<Viewe
         "poll".to_string(),
         container_path.to_string(),
     ];
-    let (stdout, stderr, code) =
-        exec_oneshot_streams_as(container_id, "claude", cmd, Vec::new()).await?;
+    let (stdout, stderr, code) = ContainerTarget::docker(container_id)
+        .exec_oneshot_streams_as("claude", cmd, Vec::new())
+        .await?;
     if code != 0 && code != 4 {
         return Err(format!(
             "Could not check the file: {}",

app/src-tauri/src/file_viewer/resolve.rs

@@ -10,8 +10,8 @@
 //! hold the resolved path, not the one that was clicked.
 
 use crate::commands::file_commands::validate_container_path;
-use crate::docker::exec::exec_oneshot_streams_as;
 use crate::docker::CONTAINER_HOME;
+use crate::host::ContainerTarget;
 
 pub const MAX_CANDIDATES: usize = 16;
 const MAX_RAW_LEN: usize = 4096;
@@ -136,8 +136,9 @@ pub async fn probe_candidates(
 ) -> Result<Vec<String>, String> {
     let mut cmd: Vec<String> = vec!["sh".into(), "-c".into(), PROBE_SCRIPT.into(), "probe".into()];
     cmd.extend(candidates.iter().cloned());
-    let (stdout, _stderr, _code) =
-        exec_oneshot_streams_as(container_id, "claude", cmd, Vec::new()).await?;
+    let (stdout, _stderr, _code) = ContainerTarget::docker(container_id)
+        .exec_oneshot_streams_as("claude", cmd, Vec::new())
+        .await?;
     Ok(parse_probe_output(&stdout))
 }
 

app/src-tauri/src/file_viewer/write.rs

@@ -11,7 +11,7 @@ use serde::Serialize;
 use sha2::{Digest, Sha256};
 
 use crate::commands::file_commands::clip_container_text;
-use crate::docker::exec::{exec_oneshot_streams_as, ExecSessionManager};
+use crate::host::{ContainerTarget, ExecSessionManager};
 
 /// Spec §4/§5: only untruncated (≤ 1 MiB) text is editable, so nothing larger is saved.
 pub const MAX_WRITE_BYTES: usize = 1024 * 1024;
@@ -180,12 +180,14 @@ pub async fn write_file(
 ) -> Result<SavedFile, String> {
     check_write_input(bytes.len(), base_hash)?;
     let tmp_name = format!("triple-c-viewer-{}", uuid::Uuid::new_v4().simple());
+    let container = ContainerTarget::docker(container_id);
     let tmp_path = exec_manager
-        .write_file_to_container(container_id, &tmp_name, bytes)
+        .write_file_to_container(&container, &tmp_name, bytes)
         .await?;
     let cmd = write_command(target, &tmp_path, base_hash);
-    let (stdout, stderr, code) =
-        exec_oneshot_streams_as(container_id, "claude", cmd, Vec::new()).await?;
+    let (stdout, stderr, code) = container
+        .exec_oneshot_streams_as("claude", cmd, Vec::new())
+        .await?;
     saved_file(classify_write(code, &stdout, &stderr), bytes)
 }
 

app/src-tauri/src/host/mod.rs

@@ -0,0 +1,474 @@
+//! Where a project's container runs, and the one interface the rest of the app
+//! uses to reach inside it.
+//!
+//! Spec: `docs/superpowers/specs/2026-11-13-aws-ecs-host-design.md` ("Host
+//! abstraction"). This is phase 1 of that plan: every operation that happens
+//! *inside* a project container — one-shot and attached execs, file transfer,
+//! "is it running" — goes through [`ContainerTarget`] instead of naming
+//! `docker::exec` or bollard directly. Today the only variant is
+//! [`ContainerTarget::Docker`], which delegates to the existing code in
+//! `docker/exec.rs` and `docker/container.rs` with no change in behaviour. An
+//! AWS variant (reached through the in-container agent) slots in beside it.
+//!
+//! ## Why an enum and not a trait object
+//!
+//! The set of hosts is closed and known at compile time, every method is async,
+//! and a `dyn` async trait would need boxing on every call (or the
+//! `async-trait` crate) for no benefit. Adding a host means adding a variant and
+//! letting the compiler point at every `match` that needs an arm.
+//!
+//! ## What does *not* go through here
+//!
+//! Things that only make sense for the local Docker host: image build/pull,
+//! base-image migration, snapshot commits, volumes, the LiteLLM gateway and STT
+//! sidecars, and (until phase 1b) container create/start/stop and the `die`
+//! event stream. Those keep calling `crate::docker` directly. The
+//! `no_container_interior_bollard_outside_the_host_layer` test pins which files
+//! may still do so.
+
+pub mod sessions;
+
+pub use crate::docker::exec::{
+    MAX_DROP_BYTES, OUTPUT_LIMIT_MARKER, PROC_NET_OUTPUT_LIMIT,
+};
+pub use sessions::ExecSessionManager;
+
+use bytes::Bytes;
+use futures_util::Stream;
+use std::pin::Pin;
+use tokio::io::AsyncWrite;
+
+use crate::docker;
+use crate::models::Project;
+
+/// One chunk of output from an exec, already demultiplexed.
+///
+/// Host-neutral stand-in for bollard's `LogOutput`. With `tty = true` there is
+/// no stdout/stderr split and everything arrives as [`ExecChunk::StdOut`] (Docker
+/// reports a TTY stream as `Console`, which maps here too — consumers that cared
+/// treated the two the same).
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum ExecChunk {
+    StdOut(Bytes),
+    StdErr(Bytes),
+    /// stdin echo or anything else a host might surface. Consumers ignore it.
+    Other(Bytes),
+}
+
+impl ExecChunk {
+    pub fn into_bytes(self) -> Bytes {
+        match self {
+            ExecChunk::StdOut(b) | ExecChunk::StdErr(b) | ExecChunk::Other(b) => b,
+        }
+    }
+}
+
+pub type ExecOutputStream = Pin<Box<dyn Stream<Item = Result<ExecChunk, String>> + Send>>;
+
+/// An exec that has been created and started with its streams attached.
+///
+/// `input` is a sink that is never read when the exec was opened with
+/// `attach_stdin: false`.
+pub struct AttachedExec {
+    pub exec_id: String,
+    pub output: ExecOutputStream,
+    pub input: Pin<Box<dyn AsyncWrite + Send>>,
+}
+
+/// Everything about an attached exec except where it runs.
+///
+/// Defaults match what this app has always used: run as `claude` in
+/// `/workspace`, no TTY, stdin attached, no extra env.
+#[derive(Debug, Clone)]
+pub struct ExecSpec {
+    pub cmd: Vec<String>,
+    pub user: String,
+    pub working_dir: Option<String>,
+    pub env: Vec<String>,
+    pub tty: bool,
+    pub attach_stdin: bool,
+}
+
+impl ExecSpec {
+    pub fn new(cmd: Vec<String>) -> Self {
+        Self {
+            cmd,
+            user: "claude".to_string(),
+            working_dir: Some("/workspace".to_string()),
+            env: Vec::new(),
+            tty: false,
+            attach_stdin: true,
+        }
+    }
+    pub fn user(mut self, user: &str) -> Self {
+        self.user = user.to_string();
+        self
+    }
+    pub fn working_dir(mut self, dir: Option<&str>) -> Self {
+        self.working_dir = dir.map(str::to_string);
+        self
+    }
+    pub fn env(mut self, env: Vec<String>) -> Self {
+        self.env = env;
+        self
+    }
+    pub fn tty(mut self, tty: bool) -> Self {
+        self.tty = tty;
+        self
+    }
+    pub fn no_stdin(mut self) -> Self {
+        self.attach_stdin = false;
+        self
+    }
+}
+
+/// A byte stream of a tar archive read out of a container.
+pub type ArchiveStream = Pin<Box<dyn Stream<Item = Result<Bytes, String>> + Send>>;
+
+/// A specific project container on a specific host.
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub enum ContainerTarget {
+    /// A container on the local Docker daemon, by id or name.
+    Docker { container_id: String },
+}
+
+impl ContainerTarget {
+    pub fn docker(container_id: impl Into<String>) -> Self {
+        ContainerTarget::Docker {
+            container_id: container_id.into(),
+        }
+    }
+
+    /// The target for a project's container, if it has one yet.
+    pub fn for_project(project: &Project) -> Option<Self> {
+        project.container_id.as_deref().map(Self::docker)
+    }
+
+    /// The host-specific identifier (a Docker container id today). For logs
+    /// and for keying per-container state; never parse it.
+    pub fn id(&self) -> &str {
+        match self {
+            ContainerTarget::Docker { container_id } => container_id,
+        }
+    }
+
+    // ── state ────────────────────────────────────────────────────────────────
+
+    /// Whether the container is running. An inspect failure (gone, daemon
+    /// down) reads as `false`, as `docker::is_container_running` always has.
+    pub async fn is_running(&self) -> Result<bool, String> {
+        match self {
+            ContainerTarget::Docker { container_id } => {
+                docker::container::is_container_running(container_id).await
+            }
+        }
+    }
+
+    // ── one-shot execs ───────────────────────────────────────────────────────
+
+    /// Run as `claude`, return combined output. Errors on a non-UTF-8-safe
+    /// transport failure only; a non-zero exit is *not* an error here.
+    pub async fn exec_oneshot(&self, cmd: Vec<String>) -> Result<String, String> {
+        match self {
+            ContainerTarget::Docker { container_id } => {
+                docker::exec::exec_oneshot(container_id, cmd).await
+            }
+        }
+    }
+
+    pub async fn exec_oneshot_env(
+        &self,
+        cmd: Vec<String>,
+        env: Vec<String>,
+    ) -> Result<String, String> {
+        match self {
+            ContainerTarget::Docker { container_id } => {
+                docker::exec::exec_oneshot_env(container_id, cmd, env).await
+            }
+        }
+    }
+
+    pub async fn exec_oneshot_env_status(
+        &self,
+        cmd: Vec<String>,
+        env: Vec<String>,
+    ) -> Result<(String, i64), String> {
+        match self {
+            ContainerTarget::Docker { container_id } => {
+                docker::exec::exec_oneshot_env_status(container_id, cmd, env).await
+            }
+        }
+    }
+
+    pub async fn exec_oneshot_as(
+        &self,
+        user: &str,
+        cmd: Vec<String>,
+        env: Vec<String>,
+    ) -> Result<(String, i64), String> {
+        match self {
+            ContainerTarget::Docker { container_id } => {
+                docker::exec::exec_oneshot_as(container_id, user, cmd, env).await
+            }
+        }
+    }
+
+    pub async fn exec_oneshot_limited(
+        &self,
+        user: &str,
+        cmd: Vec<String>,
+        limit: usize,
+    ) -> Result<(String, i64), String> {
+        match self {
+            ContainerTarget::Docker { container_id } => {
+                docker::exec::exec_oneshot_limited(container_id, user, cmd, limit).await
+            }
+        }
+    }
+
+    /// stdout and stderr kept apart: `(stdout, stderr, exit_code)`.
+    pub async fn exec_oneshot_streams_as(
+        &self,
+        user: &str,
+        cmd: Vec<String>,
+        env: Vec<String>,
+    ) -> Result<(String, String, i64), String> {
+        match self {
+            ContainerTarget::Docker { container_id } => {
+                docker::exec::exec_oneshot_streams_as(container_id, user, cmd, env).await
+            }
+        }
+    }
+
+    /// Start a command and return without waiting or reading its output.
+    /// Returns the exec id.
+    pub async fn exec_detached(&self, spec: ExecSpec) -> Result<String, String> {
+        match self {
+            ContainerTarget::Docker { container_id } => {
+                docker::exec::exec_detached(container_id, &spec).await
+            }
+        }
+    }
+
+    // ── attached execs ───────────────────────────────────────────────────────
+
+    /// Run as `claude` in `/workspace` with stdin attached.
+    pub async fn attach_exec(&self, cmd: Vec<String>, tty: bool) -> Result<AttachedExec, String> {
+        self.attach(ExecSpec::new(cmd).tty(tty)).await
+    }
+
+    pub async fn attach(&self, spec: ExecSpec) -> Result<AttachedExec, String> {
+        match self {
+            ContainerTarget::Docker { container_id } => {
+                docker::exec::create_attached_exec_spec(container_id, &spec).await
+            }
+        }
+    }
+
+    /// The exit code of an exec this target started, once it has finished.
+    /// `None` if the host could not say.
+    pub async fn wait_exec_exit(&self, exec_id: &str) -> Option<i64> {
+        match self {
+            ContainerTarget::Docker { .. } => docker::exec::wait_for_exec_exit(exec_id).await,
+        }
+    }
+
+    pub async fn resize_exec(&self, exec_id: &str, cols: u16, rows: u16) -> Result<(), String> {
+        match self {
+            ContainerTarget::Docker { .. } => docker::exec::resize_exec(exec_id, cols, rows).await,
+        }
+    }
+
+    // ── files ────────────────────────────────────────────────────────────────
+
+    /// The container user's `(uid, gid)`, falling back to `(1000, 1000)`.
+    pub async fn user_ids(&self) -> (u64, u64) {
+        match self {
+            ContainerTarget::Docker { container_id } => {
+                docker::exec::container_user_ids(container_id).await
+            }
+        }
+    }
+
+    /// Write `data` to `dest_dir/file_name` as root-owned with `mode`.
+    pub async fn upload_bytes(
+        &self,
+        dest_dir: &str,
+        file_name: &str,
+        data: &[u8],
+        mode: u32,
+    ) -> Result<String, String> {
+        match self {
+            ContainerTarget::Docker { container_id } => {
+                docker::exec::upload_bytes_to_container(
+                    container_id,
+                    dest_dir,
+                    file_name,
+                    data,
+                    mode,
+                )
+                .await
+            }
+        }
+    }
+
+    /// [`Self::upload_bytes`] with the owner set to `ids`.
+    pub async fn upload_bytes_with_ids(
+        &self,
+        dest_dir: &str,
+        file_name: &str,
+        data: &[u8],
+        mode: u32,
+        ids: (u64, u64),
+    ) -> Result<String, String> {
+        match self {
+            ContainerTarget::Docker { container_id } => {
+                docker::exec::upload_bytes_with_ids(
+                    container_id,
+                    dest_dir,
+                    file_name,
+                    data,
+                    mode,
+                    ids,
+                )
+                .await
+            }
+        }
+    }
+
+    /// Copy a host file in, owned by the container user.
+    pub async fn upload_host_file(
+        &self,
+        host_path: &str,
+        dest_dir: &str,
+        dest_name: &str,
+    ) -> Result<String, String> {
+        match self {
+            ContainerTarget::Docker { container_id } => {
+                docker::exec::upload_host_file_to_container(
+                    container_id,
+                    host_path,
+                    dest_dir,
+                    dest_name,
+                )
+                .await
+            }
+        }
+    }
+
+    /// [`Self::upload_host_file`] with the owner ids already known.
+    pub async fn upload_host_file_with_ids(
+        &self,
+        host_path: &str,
+        dest_dir: &str,
+        dest_name: &str,
+        ids: (u64, u64),
+    ) -> Result<String, String> {
+        match self {
+            ContainerTarget::Docker { container_id } => {
+                docker::exec::upload_host_file_with_ids(
+                    container_id,
+                    host_path,
+                    dest_dir,
+                    dest_name,
+                    ids,
+                )
+                .await
+            }
+        }
+    }
+
+    /// Read `path` out of the container as a tar stream (Docker's archive
+    /// API). Dropping the stream cancels the transfer.
+    pub fn download_archive(&self, path: &str) -> ArchiveStream {
+        match self {
+            ContainerTarget::Docker { container_id } => {
+                docker::exec::download_archive(container_id, path)
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn exec_spec_defaults_match_what_the_app_always_used() {
+        let s = ExecSpec::new(vec!["true".into()]);
+        assert_eq!(s.user, "claude");
+        assert_eq!(s.working_dir.as_deref(), Some("/workspace"));
+        assert!(s.env.is_empty());
+        assert!(!s.tty);
+        assert!(s.attach_stdin);
+    }
+
+    #[test]
+    fn for_project_follows_the_container_id() {
+        let mut p: Project = serde_json::from_value(serde_json::json!({
+            "id": "p1", "name": "p", "paths": [], "container_id": null,
+            "status": "stopped", "backend": "anthropic",
+            "allow_docker_access": false, "full_permissions": false,
+            "created_at": "now", "updated_at": "now"
+        }))
+        .expect("minimal project deserializes");
+        assert_eq!(ContainerTarget::for_project(&p), None);
+        p.container_id = Some("abc".into());
+        assert_eq!(
+            ContainerTarget::for_project(&p),
+            Some(ContainerTarget::docker("abc"))
+        );
+        assert_eq!(ContainerTarget::docker("abc").id(), "abc");
+    }
+
+    /// Phase 1's boundary, pinned: outside `docker/` and `host/`, only the
+    /// files listed here may name bollard or `docker::exec`. Each entry is
+    /// Docker-only by nature (migration, snapshots, sidecars) or is scheduled
+    /// for phase 1b (lifecycle, the `die` event stream). Shrink this list; do
+    /// not grow it — new container-interior code goes through
+    /// [`ContainerTarget`].
+    #[test]
+    fn no_container_interior_bollard_outside_the_host_layer() {
+        const ALLOWED: &[&str] = &[
+            // Docker-only: base-image migration replays apt / restores a payload.
+            "commands/migration_commands.rs",
+            // Phase 1b: lifecycle and the `die` event stream.
+            "container_watch.rs",
+        ];
+        let src = std::path::Path::new(env!("CARGO_MANIFEST_DIR")).join("src");
+        let mut offenders = Vec::new();
+        let mut stack = vec![src.clone()];
+        while let Some(dir) = stack.pop() {
+            for entry in std::fs::read_dir(&dir).unwrap() {
+                let path = entry.unwrap().path();
+                let rel = path
+                    .strip_prefix(&src)
+                    .unwrap()
+                    .to_string_lossy()
+                    .replace('\\', "/");
+                if path.is_dir() {
+                    if rel != "docker" && rel != "host" {
+                        stack.push(path);
+                    }
+                    continue;
+                }
+                if !rel.ends_with(".rs") || ALLOWED.contains(&rel.as_str()) {
+                    continue;
+                }
+                let text = std::fs::read_to_string(&path).unwrap();
+                if text.contains("bollard::")
+                    || text.contains("docker::exec")
+                    || text.contains("get_docker")
+                {
+                    offenders.push(rel);
+                }
+            }
+        }
+        offenders.sort();
+        assert!(
+            offenders.is_empty(),
+            "these files reach into the container without going through host::ContainerTarget: {:?}",
+            offenders
+        );
+    }
+}

app/src-tauri/src/host/sessions.rs

@@ -0,0 +1,214 @@
+//! Interactive exec sessions — terminals and the audio bridge — keyed by the
+//! frontend's session id. Host-neutral: every session holds the
+//! [`ContainerTarget`] it was opened on and does all its I/O through it.
+//! (Moved here from `docker/exec.rs` in phase 1 of the AWS host work.)
+
+use futures_util::StreamExt;
+use std::collections::HashMap;
+use std::sync::Arc;
+use tokio::io::AsyncWriteExt;
+use tokio::sync::{mpsc, Mutex};
+
+use super::{AttachedExec, ContainerTarget};
+
+pub struct ExecSession {
+    pub exec_id: String,
+    pub target: ContainerTarget,
+    pub input_tx: mpsc::UnboundedSender<Vec<u8>>,
+    shutdown_tx: mpsc::Sender<()>,
+}
+
+impl ExecSession {
+    pub async fn send_input(&self, data: Vec<u8>) -> Result<(), String> {
+        self.input_tx
+            .send(data)
+            .map_err(|e| format!("Failed to send input: {}", e))
+    }
+
+    #[allow(dead_code)]
+    pub async fn resize(&self, cols: u16, rows: u16) -> Result<(), String> {
+        self.target.resize_exec(&self.exec_id, cols, rows).await
+    }
+
+    pub fn shutdown(&self) {
+        let _ = self.shutdown_tx.try_send(());
+    }
+}
+
+pub struct ExecSessionManager {
+    sessions: Arc<Mutex<HashMap<String, ExecSession>>>,
+}
+
+impl ExecSessionManager {
+    pub fn new() -> Self {
+        Self {
+            sessions: Arc::new(Mutex::new(HashMap::new())),
+        }
+    }
+
+    pub async fn create_session<F>(
+        &self,
+        target: &ContainerTarget,
+        session_id: &str,
+        cmd: Vec<String>,
+        on_output: F,
+        on_exit: Box<dyn FnOnce() + Send>,
+    ) -> Result<(), String>
+    where
+        F: Fn(Vec<u8>) + Send + 'static,
+    {
+        self.create_session_with_tty(target, session_id, cmd, true, on_output, on_exit)
+            .await
+    }
+
+    pub async fn create_session_with_tty<F>(
+        &self,
+        target: &ContainerTarget,
+        session_id: &str,
+        cmd: Vec<String>,
+        tty: bool,
+        on_output: F,
+        on_exit: Box<dyn FnOnce() + Send>,
+    ) -> Result<(), String>
+    where
+        F: Fn(Vec<u8>) + Send + 'static,
+    {
+        let AttachedExec {
+            exec_id,
+            mut output,
+            mut input,
+        } = target.attach_exec(cmd, tty).await?;
+
+        let (input_tx, mut input_rx) = mpsc::unbounded_channel::<Vec<u8>>();
+        let (shutdown_tx, mut shutdown_rx) = mpsc::channel::<()>(1);
+
+        // Output reader task
+        let session_id_clone = session_id.to_string();
+        let shutdown_tx_clone = shutdown_tx.clone();
+        tokio::spawn(async move {
+            loop {
+                tokio::select! {
+                    msg = output.next() => {
+                        match msg {
+                            Some(Ok(output)) => {
+                                on_output(output.into_bytes().to_vec());
+                            }
+                            Some(Err(e)) => {
+                                log::error!("Exec output error for {}: {}", session_id_clone, e);
+                                break;
+                            }
+                            None => {
+                                log::info!("Exec output stream ended for {}", session_id_clone);
+                                break;
+                            }
+                        }
+                    }
+                    _ = shutdown_rx.recv() => {
+                        log::info!("Exec session {} shutting down", session_id_clone);
+                        break;
+                    }
+                }
+            }
+            on_exit();
+            let _ = shutdown_tx_clone;
+        });
+
+        // Input writer task
+        tokio::spawn(async move {
+            while let Some(data) = input_rx.recv().await {
+                if let Err(e) = input.write_all(&data).await {
+                    log::error!("Failed to write to exec stdin: {}", e);
+                    break;
+                }
+            }
+        });
+
+        let session = ExecSession {
+            exec_id,
+            target: target.clone(),
+            input_tx,
+            shutdown_tx,
+        };
+
+        self.sessions
+            .lock()
+            .await
+            .insert(session_id.to_string(), session);
+
+        Ok(())
+    }
+
+    pub async fn send_input(&self, session_id: &str, data: Vec<u8>) -> Result<(), String> {
+        let sessions = self.sessions.lock().await;
+        let session = sessions
+            .get(session_id)
+            .ok_or_else(|| format!("Session {} not found", session_id))?;
+        session.send_input(data).await
+    }
+
+    pub async fn resize(&self, session_id: &str, cols: u16, rows: u16) -> Result<(), String> {
+        // Clone the exec_id under the lock, then drop the lock before the
+        // async host call to avoid holding the mutex across await.
+        let (exec_id, target) = {
+            let sessions = self.sessions.lock().await;
+            let session = sessions
+                .get(session_id)
+                .ok_or_else(|| format!("Session {} not found", session_id))?;
+            (session.exec_id.clone(), session.target.clone())
+        };
+        target.resize_exec(&exec_id, cols, rows).await
+    }
+
+    pub async fn close_session(&self, session_id: &str) {
+        let mut sessions = self.sessions.lock().await;
+        if let Some(session) = sessions.remove(session_id) {
+            session.shutdown();
+        }
+    }
+
+    pub async fn close_sessions_for_container(&self, container_id: &str) {
+        let mut sessions = self.sessions.lock().await;
+        let ids_to_close: Vec<String> = sessions
+            .iter()
+            .filter(|(_, s)| s.target.id() == container_id)
+            .map(|(id, _)| id.clone())
+            .collect();
+        for id in ids_to_close {
+            if let Some(session) = sessions.remove(&id) {
+                session.shutdown();
+            }
+        }
+    }
+
+    pub async fn close_all_sessions(&self) {
+        let mut sessions = self.sessions.lock().await;
+        for (_, session) in sessions.drain() {
+            session.shutdown();
+        }
+    }
+
+    /// The container a session was opened on — reuse it for side-channel work
+    /// on the same session (image paste, file drop, audio bridge) rather than
+    /// rebuilding a target from an id, which would assume the host.
+    pub async fn get_target(&self, session_id: &str) -> Result<ContainerTarget, String> {
+        let sessions = self.sessions.lock().await;
+        let session = sessions
+            .get(session_id)
+            .ok_or_else(|| format!("Session {} not found", session_id))?;
+        Ok(session.target.clone())
+    }
+
+    pub async fn write_file_to_container(
+        &self,
+        target: &ContainerTarget,
+        file_name: &str,
+        data: &[u8],
+    ) -> Result<String, String> {
+        // Owned by the container user, stamped now: a default tar header would
+        // land it as root:root/1970 and Claude Code could not rewrite it.
+        let ids = target.user_ids().await;
+        target
+            .upload_bytes_with_ids("/tmp", file_name, data, 0o644, ids)
+            .await
+    }
+}

app/src-tauri/src/lib.rs

@@ -7,6 +7,7 @@ mod container_watch;
 #[cfg(target_os = "linux")]
 mod linux_media;
 mod docker;
+mod host;
 pub mod file_viewer;
 mod install_helper;
 mod logging;
@@ -22,7 +23,7 @@ use std::sync::{Arc, Mutex};
 use std::time::Duration;
 
 use auth_bridge::AuthBridgeManager;
-use docker::exec::ExecSessionManager;
+use host::ExecSessionManager;
 use storage::projects_store::ProjectsStore;
 use storage::settings_store::SettingsStore;
 use tauri::async_runtime::JoinHandle;

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

@@ -5,16 +5,13 @@
 
 use std::time::Duration;
 
-use bollard::container::LogOutput;
 use futures_util::{Stream, StreamExt};
 use tauri::{AppHandle, Emitter};
 use tokio::io::{AsyncWrite, AsyncWriteExt};
 use tokio::sync::oneshot;
 
 use crate::commands::auth_token_commands::{push_capped_tail, AnsiStripper, SUBMIT_ENTER_DELAY};
-use crate::docker::exec::{
-    create_attached_exec_as, exec_oneshot_as, wait_for_exec_exit, AttachedExec,
-};
+use crate::host::{AttachedExec, ContainerTarget, ExecChunk, ExecSpec};
 
 pub const CODE_EVENT: &str = "marketplace-gh-login-code";
 pub const OUTPUT_EVENT: &str = "marketplace-gh-login-output";
@@ -32,8 +29,8 @@ const MAX_PENDING_LINE: usize = 4096;
 /// script around it (whose text contains the same words); errors are ignored.
 const CANCEL_PKILL: [&str; 3] = ["pkill", "-f", "gh auth login --hostname"];
 
-/// Constant script; the host is `$1` (argv, never interpolated), because
-/// `create_attached_exec_as` takes no env.
+/// Constant script; the host is `$1` (argv, never interpolated); the attached
+/// exec is opened with no extra env.
 ///
 /// * `GH_CONFIG_DIR` / `GIT_CONFIG_GLOBAL` live in a temp dir removed on exit,
 ///   so the container is never left logged in. The `HUP INT TERM` trap turns a
@@ -150,9 +147,9 @@ fn failure_tail(transcript: &str) -> String {
 
 /// Pre-flight N9 / review fix 1: stop the in-container login after any
 /// failed attempt.
-async fn kill_container_login(container_id: &str) {
+async fn kill_container_login(target: &ContainerTarget) {
     let cmd = CANCEL_PKILL.iter().map(|s| s.to_string()).collect();
-    let _ = exec_oneshot_as(container_id, "claude", cmd, vec![]).await;
+    let _ = target.exec_oneshot_as("claude", cmd, vec![]).await;
 }
 
 /// Hand `result` back, running `cleanup` first when it is a failure.
@@ -187,7 +184,7 @@ async fn drive_login<S, W, E>(
     mut emit: E,
 ) -> Result<String, String>
 where
-    S: Stream<Item = Result<LogOutput, bollard::errors::Error>> + Unpin,
+    S: Stream<Item = Result<ExecChunk, String>> + Unpin,
     W: AsyncWrite + Unpin,
     E: FnMut(&'static str, serde_json::Value),
 {
@@ -262,7 +259,7 @@ where
 pub async fn run_gh_container_login(
     app: &AppHandle,
     account_id: &str,
-    container_id: &str,
+    target: &ContainerTarget,
     host: &str,
     mut cancel: oneshot::Receiver<()>,
 ) -> Result<String, String> {
@@ -273,20 +270,20 @@ pub async fn run_gh_container_login(
         exec_id,
         output,
         input,
-    } = create_attached_exec_as(
-        container_id,
-        vec![
-            "sh".to_string(),
-            "-c".to_string(),
-            GH_LOGIN_SCRIPT.to_string(),
-            "triple-c-gh-login".to_string(),
-            host.to_string(),
-        ],
-        true,
-        "claude",
-        "/home/claude",
-    )
-    .await?;
+    } = target
+        .attach(
+            ExecSpec::new(vec![
+                "sh".to_string(),
+                "-c".to_string(),
+                GH_LOGIN_SCRIPT.to_string(),
+                "triple-c-gh-login".to_string(),
+                host.to_string(),
+            ])
+            .tty(true)
+            .user("claude")
+            .working_dir(Some("/home/claude")),
+        )
+        .await?;
 
     let deadline = tokio::time::Instant::now() + LOGIN_TIMEOUT;
     let result = async {
@@ -305,7 +302,7 @@ pub async fn run_gh_container_login(
         if let Some(token) = extract_token(&transcript) {
             return Ok(token);
         }
-        let status = wait_for_exec_exit(&exec_id).await;
+        let status = target.wait_exec_exit(&exec_id).await;
         Err(format!(
             "gh did not complete the sign-in (exit status {}). Nothing was stored.\n{}",
             status
@@ -315,7 +312,7 @@ pub async fn run_gh_container_login(
         ))
     }
     .await;
-    cleanup_on_error(result, || kill_container_login(container_id)).await
+    cleanup_on_error(result, || kill_container_login(target)).await
 }
 
 #[cfg(test)]
@@ -496,23 +493,19 @@ mod tests {
     /// successful one does not.
     mod teardown {
         use super::super::*;
-        use bollard::container::LogOutput;
         use futures_util::stream;
         use std::pin::Pin;
         use std::sync::{Arc, Mutex};
         use std::task::{Context, Poll};
 
-        type Frame = Result<LogOutput, bollard::errors::Error>;
+        type Frame = Result<ExecChunk, String>;
 
         fn out(s: &'static str) -> Frame {
-            Ok(LogOutput::StdOut { message: s.into() })
+            Ok(ExecChunk::StdOut(s.into()))
         }
 
         fn lost() -> Frame {
-            Err(bollard::errors::Error::DockerResponseServerError {
-                status_code: 500,
-                message: "connection reset".to_string(),
-            })
+            Err("connection reset".to_string())
         }
 
         /// Records every write separately; or fails every write.

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

@@ -4,7 +4,7 @@
 use std::time::Duration;
 
 use super::payload::Payload;
-use crate::docker::exec::{exec_oneshot_as, exec_oneshot_streams_as, upload_bytes_to_container};
+use crate::host::ContainerTarget;
 use crate::models::marketplace::{SkippedItem, SyncReport};
 
 /// Where the payload and the script are uploaded. Owned by `claude`.
@@ -57,10 +57,12 @@ fn run_script_env() -> Vec<String> {
     vec!["HOME=/home/claude".to_string()]
 }
 
-async fn wait_until_ready(container_id: &str) -> Result<(), String> {
+async fn wait_until_ready(target: &ContainerTarget) -> Result<(), String> {
     let deadline = tokio::time::Instant::now() + READY_TIMEOUT;
     loop {
-        let (_, code) = exec_oneshot_as(container_id, "root", ready_probe_cmd(), vec![]).await?;
+        let (_, code) = target
+            .exec_oneshot_as("root", ready_probe_cmd(), vec![])
+            .await?;
         if code == 0 {
             return Ok(());
         }
@@ -91,34 +93,28 @@ fn tail(text: &str, max: usize) -> &str {
 /// Wait for readiness, upload the payload and the script, run the script as
 /// `claude`, and return its report.
 pub async fn sync_container(container_id: &str, payload: &Payload) -> Result<SyncReport, String> {
-    wait_until_ready(container_id).await?;
+    let target = ContainerTarget::docker(container_id);
+    wait_until_ready(&target).await?;
 
-    let (out, code) = exec_oneshot_as(container_id, "root", sh(PREPARE_SCRIPT), vec![]).await?;
+    let (out, code) = target
+        .exec_oneshot_as("root", sh(PREPARE_SCRIPT), vec![])
+        .await?;
     if code != 0 {
         return Err(format!(
             "Could not prepare the container for the marketplace sync: {}",
             tail(&out, 500)
         ));
     }
-    upload_bytes_to_container(
-        container_id,
-        INCOMING_DIR,
-        "payload.tar",
-        &payload.tar,
-        0o644,
-    )
-    .await?;
-    upload_bytes_to_container(
-        container_id,
-        INCOMING_DIR,
-        "sync.sh",
-        SYNC_SCRIPT.as_bytes(),
-        0o755,
-    )
-    .await?;
+    target
+        .upload_bytes(INCOMING_DIR, "payload.tar", &payload.tar, 0o644)
+        .await?;
+    target
+        .upload_bytes(INCOMING_DIR, "sync.sh", SYNC_SCRIPT.as_bytes(), 0o755)
+        .await?;
 
-    let (stdout, stderr, code) =
-        exec_oneshot_streams_as(container_id, "claude", run_script_cmd(), run_script_env()).await?;
+    let (stdout, stderr, code) = target
+        .exec_oneshot_streams_as("claude", run_script_cmd(), run_script_env())
+        .await?;
     parse_report(&stdout).map_err(|e| {
         format!(
             "The marketplace sync script failed (exit {code}): {e}. {}",

app/src-tauri/src/web_terminal/server.rs

@@ -8,7 +8,7 @@ use serde::{Deserialize, Serialize};
 use tokio::sync::watch;
 use tower_http::cors::CorsLayer;
 
-use crate::docker::exec::ExecSessionManager;
+use crate::host::ExecSessionManager;
 use crate::storage::projects_store::ProjectsStore;
 use crate::storage::settings_store::SettingsStore;
 

app/src-tauri/src/web_terminal/ws_handler.rs

@@ -295,9 +295,7 @@ async fn handle_open(
         return Err(format!("Project '{}' is not running", project.name));
     }
 
-    let container_id = project
-        .container_id
-        .as_ref()
+    let container = crate::host::ContainerTarget::for_project(&project)
         .ok_or_else(|| "Container not running".to_string())?;
 
     let cmd = match session_type {
@@ -329,7 +327,13 @@ async fn handle_open(
 
     state
         .exec_manager
-        .create_session(container_id, &session_id, cmd, on_output, on_exit)
+        .create_session(
+            &container,
+            &session_id,
+            cmd,
+            on_output,
+            on_exit,
+        )
         .await?;
 
     // Track this session for cleanup on disconnect

docs/superpowers/specs/2026-11-13-aws-ecs-host-design.md

@@ -0,0 +1,625 @@
+# Triple-C on AWS (ECS on EC2 / Fargate) — design
+
+Date: 2026-11-13
+Status: **draft for review** (user decisions recorded 2026-11-13). The user set the direction (local or AWS, login like the AWS CLI,
+permission check, hosting options, secrets pushed automatically, shared accounts). Everything else
+here is a proposal.
+
+## Goal
+
+A project can run its container on **AWS ECS** instead of the local Docker daemon, so it keeps
+running for days without the user's machine. The user picks the host per project. Local Docker
+keeps working exactly as it does today.
+
+The AWS flow, in the user's words:
+
+1. Pick **Local Docker** or **AWS** as the host.
+2. AWS starts with a **login**, by SSO or access keys, the same way the AWS CLI does.
+3. Triple-C **checks it has the permissions** it needs to set up the workspace.
+4. The user picks **how it is hosted**: ECS on EC2 or Fargate, ephemeral storage or EFS.
+5. SSH keys, certificates and similar uploads go to **Secrets Manager or straight to the
+   instance**, without manual steps.
+6. **A shared AWS account used by several people is the normal case**, not an edge case.
+
+### Decisions (user, 2026-11-13)
+
+| Topic | Decision |
+|---|---|
+| Who provisions | **Not necessarily an admin.** Triple-C **detects** existing Triple-C infrastructure in the account and offers **join it** or **deploy a new one**. Many users have no admin, so deploying is a first-class path, not an admin-only extra |
+| WIP push before stop | **On by default** (per project, can be turned off) |
+| Claude Code login | **Unchanged.** Anthropic login (`claude login`, OAuth through the auth bridge, or the shared token) or Bedrock, exactly as for local projects. The AWS host doesn't change how Claude authenticates |
+| Tenancy | **Strict from v1, and the default.** Most people will set this up in their own accounts. Strict costs a single user nothing extra (they onboard themselves automatically), and it means the setup is already safe the day a second person joins |
+| Connection model | **C, hybrid.** A connection is a login (profile or keys) plus a **default region**. Environments are detected per region when needed; each project records `(connection, region, environment)`. See [Connection model](#connection-model) |
+
+### Non-goals (v1)
+
+- Kubernetes/EKS, other clouds, or remote Docker hosts. The host abstraction below allows them
+  later.
+- Per-project snapshot images (`docker commit`) on AWS. See [Snapshots](#snapshots).
+- Moving an existing local project's state to AWS. A project can be switched to AWS only if its
+  folders are git repos with remotes, and it starts fresh there.
+- Running the speech-to-text container on AWS. The microphone is on the user's machine, so STT
+  stays local.
+- Docker Sandboxes, gVisor or Kata. That is a separate design.
+
+## Terminology
+
+`Project.backend` (`models/project.rs`) already means the **LLM provider** (Anthropic, Bedrock,
+Ollama, llama.cpp, OpenAI-compatible). To avoid two meanings of "backend", this design uses:
+
+| Term | Meaning |
+|---|---|
+| **Host** | Where a project's container runs: `Local` (Docker today) or `Aws` |
+| **AWS connection** | Saved credentials and region (an SSO profile or access keys), stored in app settings |
+| **Environment** | Shared infrastructure in one AWS account and region: cluster, VPC wiring, ECR, EFS, KMS key, IAM roles, log group. It is provisioned once, often by an admin, and used by many people |
+| **Workspace** | One user's project inside an environment: task definition, EFS access point, secrets, and the running task |
+| **Owner** | The AWS principal that created a workspace. Every per-user resource is tagged with it |
+
+Environment vs. workspace is the central decision. It is what makes shared accounts work: admins
+own the environment, users only ever create things inside their own workspaces.
+
+## User flow
+
+### 1. Settings → Hosts → Add AWS connection
+
+- **Auth method** (same options as the AWS CLI):
+  - **AWS profile**: any profile in `~/.aws/config`, including SSO profiles. SSO login reuses
+    `commands/aws_commands.rs` (`is_sso_profile`, `check_sso_session`, `run_sso_login`), which
+    already does this for Bedrock.
+  - **Access keys**: access key ID, secret, and an optional session token. Stored in the OS
+    keyring through `storage/secure.rs`, never in `settings.json`.
+  - Later: the SSO device flow through the SDK (`aws-sdk-ssooidc`), so SSO works without the
+    AWS CLI installed.
+- **Default region.** Used for detection and preselected for new projects. Other regions are
+  scanned only when the user picks one for a project.
+- When saved, call `sts:GetCallerIdentity` and show **"Signed in as `<arn>`"**. The identity
+  determines the owner ID (see [Multi-user accounts](#multi-user-accounts)).
+
+AWS API calls go through the Rust SDK (`aws-config` plus the service crates). That way, access-key
+users don't need the AWS CLI. Only SSO login needs it, until the device flow lands.
+
+### 2. Detect, then join or deploy
+
+Triple-C looks for existing Triple-C infrastructure in the region in two ways, so it finds an
+environment even if one of them is missing:
+
+- the SSM parameters `/triple-c/environments/*`, written by the environment stack, whose JSON
+  value lists the environment's ARNs and IDs;
+- CloudFormation stacks tagged `triple-c:component=environment`. This catches a stack whose
+  parameter was deleted, or one that is half-deployed (`*_IN_PROGRESS`, `*_FAILED`). Those are
+  shown with their state and a "Repair or delete" action instead of being silently ignored.
+
+Detection also reads the template version each stack was deployed from, so an environment deployed
+by an older Triple-C shows **"Update available"**.
+
+What the user sees depends on what was found and what they're allowed to do:
+
+| Found | Can deploy (stack permissions) | Offered |
+|---|---|---|
+| Nothing | Yes | **Deploy a new environment** (the default path for a personal account) |
+| Nothing | No | Explanation, plus the policy JSON and a pre-filled CloudFormation console link to send to whoever owns the account |
+| One or more | Yes | **Join** `<name>` (default) or **Deploy a new one** (for example a separate region or cost boundary) |
+| One or more | No | **Join** `<name>` |
+
+**Deploy** uses the **CloudFormation template that ships with the app**
+(`aws/triple-c-environment.yaml`). A CloudFormation stack is auditable, an admin can deploy it
+without Triple-C, and deleting the stack removes everything. The app never creates environment
+resources one API call at a time. Deploy progress streams from the stack events into the same
+progress view used for local image pulls.
+
+**Joining in strict tenancy** (the default) also needs the user's **onboarding stack**: their own
+task role, EFS access-point policy entry and, if they use EC2, a dedicated capacity provider. The
+app checks whether the caller already has one:
+
+- **The caller can deploy it** (always true in their own account): Triple-C deploys
+  `triple-c-user-onboard.yaml` for them as part of joining. For the person who just deployed the
+  environment, this happens in the same flow, so a single user never sees "onboarding" as a step.
+- **The caller can't**: Triple-C produces an onboarding request for whoever runs the environment —
+  a pre-filled CloudFormation console link plus the exact parameters — and the user's "Join" stays
+  pending until the stack exists. The app re-checks whenever the user opens the dialog.
+
+### 3. Permission check
+
+There are three tiers, and the check reports which one the user is in:
+
+| Tier | Can do |
+|---|---|
+| **Environment admin** | Deploy or update the environment stack, onboard users (strict tenancy) |
+| **Workspace user** | Create, start, stop, connect to and delete **their own** workspaces in an existing environment |
+| **Insufficient** | Lists exactly which actions are missing, and offers the IAM policy JSON to send to an admin |
+
+How the check works:
+
+1. Call `iam:SimulatePrincipalPolicy` for the caller's role or user ARN, against the action list
+   for each tier, using the environment's real resource ARNs and the tag conditions a request
+   would carry.
+2. If the user can't run the simulation (common for locked-down SSO roles), fall back to read-only
+   probes (`ecs:DescribeClusters`, `ssm:GetParameter`, `secretsmanager:ListSecrets` filtered by
+   tag, `elasticfilesystem:DescribeAccessPoints`). Write actions are then marked **"unverified —
+   will be confirmed on first use"**, not "OK".
+3. Be honest about the gaps: the simulation does not apply SCPs, permission boundaries or session
+   policies. The first real create is the final check, and its error must name the denied action.
+
+The exact policies for each tier ship as files with the app (`aws/policies/*.json`). Settings
+links to them so an admin can grant them without reading this doc.
+
+### 4. Hosting options (per project, defaults per environment)
+
+| Option | Choices | Notes |
+|---|---|---|
+| Launch type | **Fargate** (default), **ECS on EC2** | EC2 choices are limited by the environment's tenancy mode, see below |
+| CPU / memory | Fargate sizes (0.25–16 vCPU) or EC2 reservations | The admin can cap these per environment |
+| Architecture | x86_64 / ARM64 (Graviton) | The image is already built for `linux/amd64` and `linux/arm64` |
+| Storage | **Hybrid** (default), **Ephemeral**, **EFS** | See [Storage](#storage) |
+| Ephemeral size | 21–200 GiB (Fargate) | On EC2, the instance volume |
+| Fargate Spot | off / on | Cheaper. Can be interrupted with 2 minutes' warning |
+| Idle auto-stop | off / N hours with no terminal or agent activity | The admin can set a maximum |
+| Repos | git URL + branch + folder name, one per `ProjectPath` | Replaces host paths on AWS |
+| Secrets delivery | **Secrets Manager** (default), **Copy at connect** | See [Secrets and uploads](#secrets-and-uploads) |
+
+### 5. Start, connect, stop
+
+- **Start** calls `ecs:RunTask` (a standalone task, not a service), tags the task with the owner,
+  and polls `DescribeTasks` until the task is `RUNNING` and Triple-C's in-container agent (see
+  [Connectivity](#connectivity)) reports ready. Progress appears in the sidebar the same way as for
+  local projects.
+- **Connect**: terminals, file viewer, browser view, auth bridge and port mappings all work through
+  the agent tunnel.
+- **Closing the app does not stop the task.** That is the point of this feature: the scheduler,
+  long agent runs and so on keep going. Reopening the app reconnects to the running tasks.
+- **Stop** first checks for unsaved work (see [Storage](#storage)), then calls `ecs:StopTask`.
+- **Delete** removes the task definition revisions, the secrets, and (after confirmation) the
+  workspace's EFS data.
+
+## Architecture
+
+### Host abstraction
+
+The app currently talks to Docker directly: `bollard` via `docker/client.rs`, about 38 exec call
+sites across terminals, file viewer, auth bridge, browser view, migration and marketplace,
+`container_watch.rs` on the Docker event stream, and `commit_container_snapshot`. Introduce a
+`ProjectHost` trait in `app/src-tauri/src/host/` with two implementations:
+
+```rust
+#[async_trait]
+trait ProjectHost {
+    async fn start(&self, p: &Project) -> Result<HostHandle>;
+    async fn stop(&self, h: &HostHandle) -> Result<()>;
+    async fn status(&self, h: &HostHandle) -> Result<HostStatus>;
+    async fn exec(&self, h: &HostHandle, cmd: ExecSpec) -> Result<ExecStream>;     // pty or piped
+    async fn read_file(&self, h: &HostHandle, path: &str) -> Result<Bytes>;
+    async fn write_file(&self, h: &HostHandle, path: &str, data: Bytes) -> Result<()>;
+    async fn tunnel(&self, h: &HostHandle, port: u16) -> Result<DuplexStream>;      // auth bridge, browser view, ports
+    fn events(&self) -> BoxStream<HostEvent>;                                         // replaces container_watch's die events
+    fn capabilities(&self) -> HostCaps;                                               // see compatibility matrix
+}
+```
+
+- `DockerHost` wraps today's code, with no behaviour change.
+- `AwsHost` implements the trait with the ECS/EC2/EFS/Secrets Manager SDK calls plus the agent.
+- **Phase 1 is a pure refactor**: every exec, file and tunnel call site moves onto the trait, with
+  local only. The AWS work then goes behind a stable interface.
+
+`HostCaps` drives the UI. Options a host can't support (VPN, Docker access, snapshots…) are shown
+disabled with the reason, instead of failing at start.
+
+### Connectivity
+
+ECS Exec (SSM Session Manager) gives a shell in a Fargate task with no inbound ports, no public IP
+and no SSH. Fargate injects the SSM agent, so the image doesn't need it. Two problems with using it
+directly:
+
+- Each `execute-command` opens a new SSM session, which takes about 1 second. That is fine for a
+  terminal, but too slow for the file viewer's polling, the auth bridge's `/proc/net` polling and
+  per-connection tunnels.
+- The session protocol is a custom websocket framing that the Rust SDK doesn't implement.
+
+**Design:** a small **in-container agent**, `triple-c-agent`, a static musl Rust binary added to
+the image.
+
+- It listens on `127.0.0.1:<port>` inside the task.
+- It multiplexes, over one authenticated connection: pty exec, piped exec, file
+  read/write/stat/list/watch, TCP tunnels to in-container loopback ports, and liveness/activity
+  for idle auto-stop.
+- The app reaches it through **one SSM port-forwarding session** (`AWS-StartPortForwardingSession`,
+  target `ecs:<cluster>_<taskId>_<runtimeId>`), opened when the project connects and reopened if
+  it drops.
+- Authentication uses a random per-task token, delivered as a secret at task start. The SSM
+  session's IAM checks (`ssm:StartSession` and `ecs:ExecuteCommand`, both scoped by the owner tag)
+  are the outer gate; the token is defence in depth.
+- v1 runs AWS's `session-manager-plugin` as a child process for the port-forward (it is
+  Apache-2.0, so Triple-C can bundle it). A native Rust client for the SSM protocol could replace
+  it later.
+
+This one channel replaces every `docker exec … socat` tunnel (auth bridge, browser view, port
+mappings) and every exec call. The web terminal and audio bridge work unchanged, because they sit
+on top of the terminal and exec layer.
+
+Network: tasks run in **private subnets** under a security group with **no inbound rules at all**.
+Outbound access goes through a NAT gateway, or VPC endpoints in restricted environments (ECR, S3,
+Logs, SSM, Secrets Manager, EFS, Bedrock). Two tasks in the same environment cannot reach each
+other.
+
+### Image
+
+**Same image, same Dockerfile.** No AWS-specific image. Changes:
+
+1. Add `triple-c-agent` to the image.
+2. The entrypoint gets an `aws` mode (`TRIPLEC_HOST=aws`) that runs before the existing steps:
+   - **Write secrets to files**: each `TRIPLEC_FILE_<name>` env var injected from Secrets Manager
+     is written to the path the entrypoint **already reads** (`/tmp/.host-ssh/…`,
+     `/tmp/.host-ca/…`, `/tmp/.host-aws/…`). After that, `sync_host_ssh`,
+     `install_corporate_ca` and the AWS config merge run unchanged.
+   - **Clone repos**: clone each repo into `/workspace/<folder>` if it isn't already there
+     (it's already there on EFS after a restart). Git credentials come from the injected git token
+     or SSH key.
+   - **Skip** the UID/GID remap (there are no bind mounts; `claude` stays UID 1000, which the EFS
+     access point matches) and the Docker-socket group setup (no socket).
+   - Start `triple-c-agent` as root, outside the `claude` user's reach, and keep the existing
+     unkillable keepalive.
+3. **Fargate restrictions** are handled by the host, not the image: no `privileged`, and no added
+   capabilities except `SYS_PTRACE`. So VPN (`NET_ADMIN`) and Docker access are unavailable. The
+   bubblewrap sandbox likely can't create user namespaces on Fargate (**verify**), so the generated
+   Claude Code settings use `enableWeakerNestedSandbox` or turn the sandbox off, with a visible
+   notice.
+
+**Getting the image into the account:**
+
+- ECR pull-through cache of `ghcr.io/shadowdao/triple-c-sandbox` (GHCR as an upstream needs a
+  GitHub token stored in Secrets Manager), or
+- the environment stack's ECR repo, filled by an admin or CI with `crane copy`.
+
+Pulling straight from GHCR over NAT also works, and is the default when the environment has no ECR mirror. Image
+updates use the existing "new image available" flow: the next start uses the new digest.
+
+### Storage
+
+| Mode | `/workspace` (repos) | `/home/claude` + `.claude` | Survives stop | Speed | Cost |
+|---|---|---|---|---|---|
+| **Ephemeral** | task storage | task storage | **No** | Fast | Included (beyond 20 GiB is billed) |
+| **Hybrid** (default) | task storage | EFS | Settings, sessions, memory, history: yes. Working tree: only what's pushed | Fast builds, fast git | Small EFS footprint |
+| **EFS** | EFS | EFS | Everything | git, `node_modules` and builds are noticeably slower over NFS | Grows with repo and dependency size |
+
+- **One EFS file system per environment, one access point per workspace.** Access point root:
+  `/triple-c/<owner>/<project-id>`, with POSIX user and group 1000. The access point is created by
+  the user and tagged with the owner (see policies).
+- **WIP push is on by default** (`wip_push_on_stop: true`, with a serde default per the
+  `default_full_permissions` pattern) and can be turned off per project.
+- **Ephemeral and Hybrid have a stop guard.** Before stopping, the app asks the agent for
+  `git status --porcelain` and any unpushed commits in each repo. If anything would be lost, it
+  offers: **Push to a `triple-c/wip/<date>` branch** (the preselected default), **Stop anyway**, or
+  **Cancel**. The same check runs before idle auto-stop. If anything is dirty, idle auto-stop
+  pushes a WIP branch instead of throwing work away.
+- **Fargate task retirement and Spot interruption** send `SIGTERM` with a short deadline (2 minutes
+  for Spot). The entrypoint's `SIGTERM` trap runs the same WIP push, best-effort, when the project
+  has it enabled.
+
+#### Snapshots
+
+`docker commit` doesn't exist on ECS. On AWS:
+
+- Anything installed outside `/home/claude` (apt packages, for example) is **lost on restart**.
+- A per-project **setup script** (stored with the project, run by the entrypoint on every start)
+  replaces snapshotting for the AWS host. Its output streams to the start-progress view.
+- Later, the app could build a per-workspace image from base image + setup script with CodeBuild
+  and push it to ECR. Out of scope for v1.
+
+### Secrets and uploads
+
+Things that are host files or keyring values today: SSH key (`ssh_key_path`), CA cert
+(`ca_cert_path`), git token, AWS config for Bedrock, `CLAUDE_CODE_OAUTH_TOKEN` / API keys, custom
+env vars marked secret, the agent token.
+
+**Secrets Manager (default)**
+
+- When the user picks an SSH key or cert for an AWS project, the app reads it on the host and
+  creates or updates a secret named `triple-c/<env>/<owner>/<project-id>/<name>`. The secret is
+  encrypted with the environment's KMS key and tagged `triple-c:owner`, `triple-c:project`,
+  `triple-c:environment`.
+- The task definition references the secrets in `containerDefinitions[].secrets`, so **the ECS
+  task execution role** fetches them at start and injects them as env vars. The entrypoint writes
+  them to files as described above.
+- **The container's own task role has no Secrets Manager permission.** Code running inside a task
+  cannot read another workspace's secrets, even though tasks share a task role in standard
+  tenancy.
+- Updating a key in the app updates the secret. The next start picks it up, and a running task
+  gets a "restart to apply" prompt.
+- Secrets Manager's 64 KB per-secret limit covers keys and cert bundles. Anything bigger is
+  rejected with a clear message.
+
+**Copy at connect**
+
+- Nothing is stored in AWS. When the app connects, it pushes the files into the running container
+  through the agent, the same way Triple-C's file upload works today, writing to tmpfs paths that
+  the entrypoint re-syncs from.
+- The task can't start a fresh clone of a **private** repo until the app connects, so the clone is
+  deferred until the first connect. Scheduled jobs can't use the credentials while the app is
+  closed, unless the files were persisted to EFS (an extra opt-in, warned about).
+- For users or orgs that don't want keys in AWS at all.
+
+**Claude Code login works the same as locally (decided).** The project's LLM backend setting
+doesn't change on the AWS host:
+
+- **Anthropic login**: `claude login` in a terminal. The OAuth callback reaches the container
+  through the auth bridge over the agent tunnel. The credential persists in `~/.claude`, which is
+  on EFS in Hybrid and EFS modes, and lost on stop in Ephemeral mode, where the UI says so. The
+  shared auth token (`use_shared_auth_token` → `CLAUDE_CODE_OAUTH_TOKEN`) is delivered as a
+  Secrets Manager secret instead of an env var.
+- **Bedrock**: the same Bedrock options as today (static keys, profile, bearer token). Profiles
+  and SSO are delivered as described above, `triple-c-sso-refresh` keeps working, and the
+  existing post-start `sync_bedrock_credentials` moves onto the agent. One optional extra,
+  **off by default**: "Use this workspace's task role for Bedrock". Under strict tenancy the task
+  role is the user's own, so this is safe and needs no credentials in the container. It is an
+  extra choice, not a replacement.
+
+### Multi-user accounts
+
+**Owner ID.** `aws:userid` from `GetCallerIdentity`:
+
+- for an IAM user, the user ID;
+- for SSO and assumed roles, `AROAxxxx:<session-name>`, where the session name is the SSO
+  username.
+
+It is stable per person and available as a policy variable, `${aws:userid}`. Every per-user
+resource is created with `triple-c:owner = ${aws:userid}`.
+
+**Control-plane isolation (ABAC).** The workspace-user policy only allows:
+
+- `ecs:RunTask`, with the request tag `triple-c:owner` set to `${aws:userid}`, on the
+  environment's cluster and task definition family prefix, plus `iam:PassRole` **only** for the
+  environment's execution and task roles;
+- `ecs:StopTask`, `ecs:ExecuteCommand`, `ssm:StartSession` where the resource tag
+  `triple-c:owner` is `${aws:userid}`. Without this, any user could open a shell in anyone's
+  task, so it's the most important rule;
+- `secretsmanager:CreateSecret`, `PutSecretValue` and `DeleteSecret` with matching request or
+  resource tags, on `triple-c/<env>/*`;
+- `elasticfilesystem:CreateAccessPoint` and `DeleteAccessPoint` with a matching tag;
+  `kms:Encrypt` and `GenerateDataKey` through Secrets Manager only (`kms:ViaService`);
+- read-only `Describe*` / `List*`. The app filters results by owner tag for display. Listing is
+  not a secret.
+
+Wildcard `${aws:userid}` conditions on ARNs and tags behave differently across ECS, EFS and
+Secrets Manager (`ecs:ResourceTag` vs `aws:ResourceTag`, and support for tag-on-create). **Every
+statement in `aws/policies/workspace-user.json` needs an integration test against a real account
+before release.**
+
+**Data-plane isolation: tenancy modes.** These are set on the environment by the admin.
+
+| Mode | For | Task role | EC2 options | Isolation |
+|---|---|---|---|---|
+| **Strict** (**default, v1**) | Everyone, from a solo account to a team | **Per-user** task role, created by the user's onboarding stack (self-deployed, or by an admin) | Privileged and Docker allowed **only on a per-user capacity provider** (dedicated EC2 instances, never shared with another owner) | Per-user IAM all the way down. EFS file system policy allows each access point only to its owner's task role |
+| **Standard** (opt-in, later) | Large teams that want fewer IAM roles | Shared, minimal (logs, SSM messages) | **Fargate only**, or EC2 with **no** privileged mode, Docker socket or `NET_ADMIN` | Containers are unprivileged and can't mount NFS, can't read secrets, and can't reach each other over the network |
+
+There is no separate "personal" mode. A solo user on strict tenancy is simply the only onboarded
+user, and the account is already safe to share.
+
+Strict tenancy's per-user `iam:PassRole` is scoped by a tag on the role
+(`iam:ResourceTag/triple-c:owner = ${aws:userid}`), not by role name, because `aws:userid`
+contains a `:`, which role names don't allow. **Verify** that `iam:PassRole` evaluates
+`iam:ResourceTag` as expected before release.
+
+Why EC2 privileged mode needs dedicated capacity: a privileged container, or one with the Docker
+socket, has root on its EC2 host, and so access to every other tenant's task on that host
+(including their injected secrets in `/proc/*/environ`). In standard tenancy the app
+**doesn't offer** Docker access or VPN for EC2 projects. In strict tenancy it offers them only on
+the user's dedicated capacity provider.
+
+**Cost visibility.** All resources carry `triple-c:owner`, `triple-c:project` and
+`triple-c:environment`. The admin activates them as cost-allocation tags. The app shows an
+estimated hourly cost per running workspace (Fargate vCPU and GB-hour rates for the region, from
+the Pricing API, cached).
+
+**Quotas.** Fargate vCPU and EFS access-point limits are per account and region. When `RunTask`
+fails because of a quota, the app says so and doesn't retry.
+
+### ECS on EC2 vs Fargate
+
+| | Fargate | ECS on EC2 |
+|---|---|---|
+| Start time | About 30–90 s (image pull every time; SOCI lazy-loading **to evaluate**) | Fast when the image is cached on a warm instance |
+| Docker access / privileged / VPN | No | Yes, on dedicated capacity |
+| GPU | No | Yes |
+| Ops | None | ASG + capacity provider, defined in the environment stack. The app only picks a capacity provider |
+| Cost when idle | 0 (task stopped) | Instances keep running unless the ASG scales in |
+| Max size | 16 vCPU / 120 GB | Instance type |
+
+ECS on EC2 uses `awsvpc` network mode too, so security groups and the no-inbound rule work the same
+way.
+
+### Lifecycle and status
+
+- `container_watch.rs` listens to Docker `die` events. For AWS, `AwsHost::events()` polls
+  `DescribeTasks` for the owner's running tasks every 15 s while the app is open, and maps
+  `stopCode` / `stoppedReason`:
+  - `EssentialContainerExited` → Stopped (exited on its own);
+  - `SpotInterruption` → Stopped (Spot);
+  - `TaskFailedToStart` → Error, with the reason;
+  - user-initiated → Stopped.
+
+  EventBridge → SQS for push notifications is a later improvement.
+- **Idle auto-stop** runs **inside** the task: the agent tracks activity (terminal I/O, agent
+  calls, running `claude` processes and scheduler jobs) and stops the task by exiting the
+  entrypoint. It doesn't depend on the app being open. Because a running scheduler job counts as
+  activity, scheduled tasks keep a workspace alive. The admin's maximum lifetime is a hard cap
+  either way.
+- Logs: `awslogs` driver to the environment's log group, stream `<owner>/<project>/<task>`. The
+  app shows start logs during startup and when a start fails.
+
+### Feature compatibility (AWS host)
+
+| Feature | Fargate | EC2 (shared) | EC2 (dedicated) |
+|---|---|---|---|
+| Terminals, web terminal, file viewer | Yes (agent) | Yes | Yes |
+| Auth bridge (OAuth callbacks) | Yes (agent tunnel) | Yes | Yes |
+| Browser view (Playwright) | Yes (agent tunnel) | Yes | Yes |
+| Port mappings | Yes, as local forwards through the agent | Yes | Yes |
+| Speech-to-text | Yes (local STT, audio over the agent) | Yes | Yes |
+| Scheduler, Mission Control | Yes, and they keep running with the app closed | Yes | Yes |
+| Marketplace installs | Yes (files copied through the agent) | Yes | Yes |
+| LLM gateway (LiteLLM) | Sidecar container in the task definition | Sidecar | Sidecar |
+| Ollama / llama.cpp on the user's machine | **No**, unless the URL is reachable from AWS | No | No |
+| Claude Code sandbox (bubblewrap) | Weaker nested mode or off (**verify**) | Weaker nested mode | Full |
+| Docker access | No | No | Yes |
+| VPN support | No | No | Yes |
+| Snapshots | Setup script instead | Setup script | Setup script |
+
+## Fit with existing conventions (CLAUDE.md)
+
+- **Detecting that a container needs recreating.** Locally, `container_needs_recreation()`
+  compares `triple-c.*` labels. On AWS, the equivalent is the **task definition revision**: the
+  app computes a fingerprint over every setting that shapes the task, stores it as a task
+  definition tag, and registers a new revision when it changes. A running task on an old revision
+  gets the same "restart to apply" signal. The CLAUDE.md rule "never put a secret in a label"
+  applies equally to tags, task definition env vars and `overrides`. Secrets go only through
+  `secrets` ARNs.
+- **Env vars are visible on EC2.** Injected secrets become container env vars, which anyone with
+  `docker inspect` or `/proc` on the instance can read. This is fine for Fargate and dedicated EC2
+  capacity, and is exactly why standard tenancy bans privileged containers on shared EC2
+  capacity.
+- **`/home/claude` stays seed-only** in Hybrid and EFS modes: it is persistent storage, the same
+  semantics as the home volume, so the existing "seed at runtime from `/opt` or
+  `/usr/local/bin`" rule carries over unchanged.
+- **Marketplace sync and Bedrock credential sync** run "after every container start". They move
+  onto `ProjectHost::write_file` / `exec`. Marketplace tokens still never leave the host: sync
+  sends the same pinned tar.
+- **Settings export/import.** `HostConnection` access keys live in the keychain, so they go into
+  `ExportedSecrets` under the same carve-out as the other keychain secrets. Importing an AWS
+  connection or environment is shown as its own preview warning, alongside the custom-image
+  warning, because it changes **where code runs and who is billed**.
+- **New IPC commands** (`aws_connect`, `aws_check_permissions`, `aws_list_environments`,
+  `aws_deploy_environment`, …) each need a `generate_handler!` entry and an `allow-*` grant in
+  `capabilities/default.json`. `build.rs` enforces this.
+- **UI.** The AWS connection goes in `components/settings/` beside the existing AWS panel. The
+  per-project hosting options go in Project Home's Config tab, not a modal. Login and permission
+  check results use the existing `StatusIndicator` (glyph + word).
+
+## Data model
+
+```rust
+// AppSettings
+pub hosts: Vec<HostConnection>,           // Local is implicit and always present
+
+pub struct HostConnection {
+    pub id: String,
+    pub name: String,
+    pub kind: HostKind,                    // Aws { auth: AwsAuth, default_region: String }
+}
+pub enum AwsAuth { Profile { name: String }, Keys { keyring_ref: String } }
+
+// Project
+pub host_id: Option<String>,               // None = Local (all existing projects)
+pub aws_placement: Option<AwsPlacement>,   // { region, environment } — set when host_id is an AWS connection
+pub aws: Option<AwsWorkspaceConfig>,
+
+pub struct AwsWorkspaceConfig {
+    pub launch_type: LaunchType,           // Fargate | Ec2 { capacity_provider }
+    pub cpu: u32, pub memory_mib: u32, pub arch: Arch,
+    pub storage: StorageMode,              // Ephemeral | Hybrid | Efs
+    pub ephemeral_gib: u32,
+    pub spot: bool,
+    pub idle_stop_minutes: Option<u32>,
+    pub repos: Vec<RepoSource>,            // { url, branch, folder } — parallel to ProjectPath
+    pub secrets_delivery: SecretsDelivery, // SecretsManager | CopyAtConnect
+    pub setup_script: Option<String>,
+    pub wip_push_on_stop: bool,
+    // runtime state (not user-edited)
+    pub task_arn: Option<String>, pub access_point_id: Option<String>,
+}
+```
+
+Existing `projects.json` files deserialize unchanged (`host_id` missing → Local).
+`Project.container_id` stays Docker-only. AWS uses `aws.task_arn`.
+
+## Shipped AWS artefacts
+
+```
+aws/
+  triple-c-environment.yaml        # CloudFormation: cluster, capacity providers, SG, EFS + policy,
+                                   # KMS key, ECR repo / pull-through rule, log group, exec+task roles,
+                                   # SSM environment parameter. Params: VPC/subnets (or create),
+                                   # tenancy mode, limits, Bedrock-on-task-role.
+  triple-c-user-onboard.yaml       # strict tenancy: per-user task role + capacity provider
+  policies/
+    environment-admin.json
+    workspace-user.json
+    task-execution-role.json
+    task-role-standard.json
+```
+
+## Phases
+
+1. **Host abstraction refactor.** `ProjectHost` trait, `DockerHost`, every call site moved. No
+   behaviour change, and the existing tests pass.
+2. **Agent.** `triple-c-agent` in the image. Optionally use it locally too behind a flag, to
+   harden it before AWS depends on it.
+3. **AWS connection + permission check.** Settings UI, SDK wiring, `GetCallerIdentity`, the tiered
+   simulation and fallback probes, policy files.
+4. **Environment + onboarding stacks.** CloudFormation templates for both, detection (SSM
+   parameters + tagged stacks, including half-deployed and outdated ones), join or deploy,
+   self-onboarding or an admin request, **strict tenancy**.
+5. **Fargate workspaces.** Ephemeral and Hybrid storage, Secrets Manager delivery, git bootstrap,
+   start/stop/status, stop guard with WIP push on by default, idle auto-stop, logs.
+6. **EFS mode, Copy-at-connect, setup scripts, cost estimate.**
+7. **ECS on EC2.** Per-user capacity providers in the onboarding stack, privileged/Docker/VPN on
+   dedicated capacity.
+8. **Standard tenancy** (opt-in), only if demand appears.
+
+## To verify before or during implementation
+
+- Whether Fargate allows bubblewrap's unprivileged user namespaces, and what Claude Code's sandbox
+  does there.
+- ABAC condition keys for each action: ECS `RunTask` tag-on-create, `ExecuteCommand`, and
+  `ssm:StartSession` against ECS targets; EFS `CreateAccessPoint` with request tags; Secrets
+  Manager name-prefix plus tag conditions with `${aws:userid}` for SSO sessions.
+- That `session-manager-plugin` port forwarding to an ECS target is stable for hours-long
+  sessions, and how quickly it reconnects.
+- Fargate image-pull time for the sandbox image, and whether SOCI indexes help.
+- That GHCR pull-through cache works for the public image.
+- That the `SIGTERM` deadline on Fargate retirement and Spot leaves enough time for a WIP push.
+
+## Connection model
+
+**Decided: C** (user, 2026-11-13). The comparison below is kept for the record.
+
+The options:
+
+- **A. One connection per environment.** Credentials + region + environment, bound together.
+- **B. One connection per identity.** Credentials only (a profile or keys, like an AWS CLI
+  profile). Each project picks a region and environment.
+- **C. Hybrid.** A connection is credentials plus a **default** region. Environments are detected
+  per region when needed, and each project records `(connection, region, environment)`.
+
+| | A. Per environment | B. Per identity | C. Hybrid |
+|---|---|---|---|
+| Mental model | Simplest: "my AWS dev box" | Matches the AWS CLI (a profile is an identity; region is a parameter) | Matches the AWS CLI, with a sensible default |
+| Setup for a solo user, one region | One step | One step, plus picking a region for each project | One step |
+| Several regions or environments, same login | Duplicate connections with the same credentials. Keys are stored twice; SSO shares a token cache, so it's only clutter | One connection | One connection |
+| Permission check | Once per connection, cached | Per environment, run lazily the first time a project uses it | Per environment, run lazily |
+| Detection cost | One region | Every region the user might use (`DescribeRegions` + a scan, slow) or a hand-kept list | Default region straight away; other regions only when the user picks one |
+| Risk of deploying to the wrong place | Low: the place is in the connection's name | Higher: an easy region-picker mistake leaves a stack in a region nobody looks at | Low: default region preselected, others must be chosen deliberately |
+| Moving a project to another region or environment | Re-point the project to another connection | Change a field | Change a field |
+| Settings export/import | Each connection is self-contained | Projects reference environments that may not exist on the importing machine | Same as B |
+| Data model / UI | Smallest | Largest (environment picker and per-environment status everywhere) | Medium |
+| Multiple AWS **accounts** | One connection each | One connection each (credentials define the account) | One connection each |
+
+**Why C:**
+
+- It costs the solo user, one-region case nothing, because the default region carries it.
+- It avoids storing the same keys repeatedly the moment someone uses a second region.
+- It keeps detection cheap and deploying deliberate.
+
+A is fine as a v1 shortcut if we want the smallest UI. Moving from A to C later is mechanical:
+connections that share credentials get merged.
+
+Consequences for implementation:
+
+- Permission check results are cached per `(connection, region, environment)` and re-run if a
+  call is denied.
+- The project's Config tab shows the region and environment with the default region preselected.
+  Choosing another region triggers detection there, and offers join or deploy as in step 2.
+- Settings export carries connections. Projects aren't exported (unchanged scope), so a dangling
+  `aws_placement` can't arrive through an import.
+
+## Remaining open questions
+
+None. Everything in "To verify" is an implementation-time check, not a product decision.