Build artifacts are namespace-scoped under `.tmp/tools-pack/out/linux/namespaces/<namespace>/`. Packaged runtime state is namespace-scoped under `.tmp/tools-pack/runtime/linux/namespaces/<namespace>/{data,logs,runtime,cache,user-data}/`. Containerized build cache lives under `.tmp/tools-pack/.docker-cache/{electron,electron-builder}/`.
The `<namespace>` suffix is unconditional so multiple developer namespaces can coexist on the same desktop. The `.desktop` file registers the `od://` scheme via `MimeType=x-scheme-handler/od;` and pre-sets `OD_PACKAGED_NAMESPACE` on the `Exec=` line so menu launches identify the correct namespace.
Headless mode targets environments without a display (WSL2, headless servers, CI) where Electron can't run. If you have a desktop, use the AppImage; if you're SSH'd into a machine or in WSL, use headless.
`--headless` makes `install`, `start`, and `stop` operate on the headless entry (`@open-design/packaged/dist/headless.mjs`) instead of the AppImage. Headless mode runs daemon + web without Electron.
-`install --headless` writes a shell launcher at `~/.local/bin/open-design-headless-<namespace>` that bakes in the namespace and resource paths. The launcher is self-contained, but the assembled app directory at those paths must remain in place — don't move it after install.
-`start --headless` spawns the headless process directly, redirects stdout/stderr to `logs/desktop/latest.log`, and waits up to 95s (35s for identity marker + 60s for web URL) before returning.
-`stop --headless` reads the same `runtime/desktop-root.json` identity marker as the AppImage path, validates `stamp.source === PACKAGED`, sends a graceful SHUTDOWN over IPC, then terminates the process tree. It does not perform the AppImage-specific process-command check.
`logs` always reads `logs/desktop/latest.log` regardless of mode, so headless output is visible via `tools-pack linux logs`.
`tools-pack linux start` always spawns the AppImage with `--appimage-extract-and-run`. Smoke testing on Ubuntu 24.04 and Arch Linux showed that direct FUSE-mounted AppImage launches make Node module loads (Express, better-sqlite3, etc.) slow enough that the daemon sidecar consistently failed to clear `apps/packaged`'s 35-second startup timeout. Extract-and-run unpacks the AppImage into `/tmp/appimage_extracted_<hex>/` and exec's the inner Electron from there, bypassing FUSE and getting daemon boot in under 5 seconds — roughly an order-of-magnitude improvement.
**Implication for end-users:** if launching the installed AppImage manually (not via `tools-pack linux start`), pass `--appimage-extract-and-run` yourself, or rely on a desktop launcher / `appimage-launcher` daemon that handles extract-and-run automatically.
### Optional system tools
`tools-pack linux install` and `tools-pack linux uninstall` invoke `update-desktop-database` and `gtk-update-icon-cache` as best-effort post-hooks. Either tool being absent (`iconCache: "missing"` in the output) is harmless — the icon and menu entry still work, the cache just isn't refreshed. Install via your distro:
`libfuse2` is needed for FUSE-mounted AppImage launch (the default mode when running an AppImage directly without `--appimage-extract-and-run`). `tools-pack linux start` always uses extract-and-run and bypasses FUSE entirely, so it does not need `libfuse2`. Most modern distros ship `libfuse2` by default; older Ubuntu LTS hosts may need `sudo apt install libfuse2t64` (or `libfuse2` on pre-24.04).
### Sandbox / chrome-sandbox
Electron 41 on Linux requires `kernel.unprivileged_userns_clone=1` (default on Arch, Ubuntu 24+, Debian 12+) or AppImage's `--no-sandbox` fallback. Most modern distros need no extra setup.
### Distro-agnostic guarantee
AppImages built natively on a rolling distro (e.g., Arch / CachyOS) link against recent glibc and may not run on stable distros (Ubuntu 22.04, Debian 12). Use `--containerized` to build against the wide-compat `electronuserland/builder:base` baseline (Ubuntu 18.04 / glibc 2.27).
### Format choice: why AppImage first
Linux desktop apps in this space split across formats: VS Code ships `.deb` + `.rpm` + Snap; Discord ships AppImage + `.deb`; Slack ships `.deb` + `.rpm`; Cursor and Obsidian ship AppImage. We start with AppImage because it is universal (one artifact runs on any glibc-compatible distro), needs no repo plumbing, and integrates cleanly with the namespace-scoped install layout. `.deb` / `.rpm` / Snap / Flatpak can land incrementally if user demand surfaces.
### Out of scope (later phases)
- AppImage signing (`--signed`) — deferred pending a GPG key infrastructure decision and a user-facing verification flow design (no ETA).
- AppImage auto-update feed (`latest-linux.yml`) — the linux electron-builder config has no `publish` block wired, so a generated feed would point users at a feed that never updates. Tracked alongside signing.
