Switch web-shell session backend from tmux to dtach

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: chapterjason

README.md

@@ -17,7 +17,7 @@ that hosts the devcontainers these features get installed into — see
 | `claude-code` | `ghcr.io/sourecode/devcontainer-features/claude-code:2` | Installs the Claude Code CLI via the official native installer into `/usr/local/bin`. Declares `~/.claude` and `~/.claude.json` as persistence targets via the `home-persist` manifest. Requires Node.js — automatically pulls in the `nvm` feature via `dependsOn`. |
 | `rtk` | `ghcr.io/sourecode/devcontainer-features/rtk:2` | Installs [rtk](https://github.com/rtk-ai/rtk), an LLM token-reducing CLI proxy, into `/usr/local/bin`. Auto-patches Claude Code via `postCreateCommand` so the hook is written against the live `~/.claude`, not the image. |
 | `context-mode` | `ghcr.io/sourecode/devcontainer-features/context-mode:2` | Installs the [`context-mode`](https://github.com/mksglu/context-mode) Claude Code plugin via `postCreateCommand`, so the plugin lands in `~/.claude/plugins` (which `home-persist` symlinks into the persistence volume when installed). |
-| `web-shell` | `ghcr.io/sourecode/devcontainer-features/web-shell:1` | Installs [web-shell](https://github.com/SoureCode/web-shell) (persistent browser terminal backed by `tmux`) from the GitHub release tarball and registers it as a systemd unit + Coder workspace app. Requires Node.js — automatically pulls in the `nvm` feature via `dependsOn`. |
+| `web-shell` | `ghcr.io/sourecode/devcontainer-features/web-shell:1` | Installs [web-shell](https://github.com/SoureCode/web-shell) (persistent browser terminal backed by `dtach`) from the GitHub release tarball and registers it as a systemd unit + Coder workspace app. Requires Node.js — automatically pulls in the `nvm` feature via `dependsOn`. |
 | `home-persist` | `ghcr.io/sourecode/devcontainer-features/home-persist:1` | Symlinks declared `$HOME` paths into a per-owner persistence volume at `/mnt/home-persist`. Features and users contribute paths via JSON manifests in `/etc/devcontainer-persist.d/`; an `onCreateCommand` resolver materializes the symlinks on every create. |
 | `nvm` | `ghcr.io/sourecode/devcontainer-features/nvm:2` | Installs [nvm](https://github.com/nvm-sh/nvm) system-wide at `/usr/local/share/nvm` and optionally a Node version (defaults to LTS), with `node`/`npm`/`npx` symlinked into `/usr/local/bin`. No yarn. |
 

src/web-shell/README.md

@@ -1,13 +1,13 @@
 # web-shell devcontainer feature
 
 Installs [web-shell](https://github.com/SoureCode/web-shell) — a persistent
-browser terminal backed by `tmux` — inside a devcontainer and registers it
+browser terminal backed by `dtach` — inside a devcontainer and registers it
 as a Coder workspace app.
 
-`web-shell` is a Node.js + xterm.js service. Every session is a `tmux` session
-on the server, so shells survive Node restarts. This feature:
+`web-shell` is a Node.js + xterm.js service. Every session is attached to a
+`dtach` socket on the server, so shells survive Node restarts. This feature:
 
-- Installs OS deps (`tmux`, `build-essential`, `python3`, `curl`, `jq`).
+- Installs OS deps (`dtach`, `build-essential`, `python3`, `curl`, `jq`).
 - Downloads the release tarball from `SoureCode/web-shell` and `npm install -g`s
   it against the Node toolchain provided by the
   [`nvm`](../nvm) feature (`dependsOn`).

src/web-shell/devcontainer-feature.json

@@ -1,8 +1,8 @@
 {
   "id": "web-shell",
-  "version": "1.0.0",
+  "version": "1.1.0",
   "name": "web-shell",
-  "description": "Installs web-shell (persistent browser terminal backed by tmux) from the GitHub release tarball into the global Node install, and registers a systemd unit so the service starts automatically on container boot. Also publishes the service as a Coder workspace app.",
+  "description": "Installs web-shell (persistent browser terminal backed by dtach) from the GitHub release tarball into the global Node install, and registers a systemd unit so the service starts automatically on container boot. Also publishes the service as a Coder workspace app.",
   "documentationURL": "https://github.com/SoureCode/devcontainer-features/tree/master/src/web-shell",
   "options": {
     "version": {

src/web-shell/install.sh

@@ -19,10 +19,10 @@ WS_PORT="${PORT:-4000}"
 WS_HOST="${HOST:-127.0.0.1}"
 WS_AUTH_TOKEN="${AUTHTOKEN:-}"
 
-# 1. OS deps: tmux for the terminal multiplexer, build-essential + python3
+# 1. OS deps: dtach as the detachable session backend, build-essential + python3
 # because node-pty compiles native bindings, plus curl/jq for release lookup.
 APT_PKGS=""
-for pkg in tmux build-essential python3 ca-certificates curl jq; do
+for pkg in dtach build-essential python3 ca-certificates curl jq; do
   if ! dpkg -s "$pkg" >/dev/null 2>&1; then
     APT_PKGS="$APT_PKGS $pkg"
   fi

terraform/web-shell/run.sh

@@ -23,10 +23,10 @@ if [ -z "$${WANTED_VERSION}" ]; then
   exit 1
 fi
 
-# Install prereqs: tmux is required at runtime; build-essential + python3 cover
+# Install prereqs: dtach is required at runtime; build-essential + python3 cover
 # node-pty's native build step when a prebuilt binding isn't available.
 need=()
-for pkg in tmux build-essential python3; do
+for pkg in dtach build-essential python3; do
   dpkg -s "$pkg" >/dev/null 2>&1 || need+=("$pkg")
 done
 if [ $${#need[@]} -gt 0 ]; then

test/web-shell/test.sh

@@ -6,7 +6,7 @@ set -e
 # shellcheck disable=SC1091
 source dev-container-features-test-lib
 
-check "tmux installed"                which tmux
+check "dtach installed"               which dtach
 check "web-shell binary in /usr/local/bin" test -x /usr/local/bin/web-shell
 check "systemd unit present"          test -f /etc/systemd/system/web-shell.service
 check "unit contains PORT env"        grep -q '^Environment=PORT=' /etc/systemd/system/web-shell.service