# Runtime state relocation + non-editable install — design (as shipped)

## Status

Shipped 2026-05-15. Supersedes
`2026-05-15-handoff-noneditable-install.md` (the narrower prereq spec).
The scope expanded during execution after a hidden constraint surfaced;
this doc records what actually shipped.

## What shipped

Two related changes, landed together:

1. **`/opt/left4me/` becomes a root-owned deploy-artifact root.** Only
   `/opt/left4me/src` lives there (eventually `/opt/left4me/scripts/`
   after the deployment-responsibility reshape too). Both `/opt/left4me`
   and `/opt/left4me/src` are root:root.
2. **Runtime mutable state moved to `/var/lib/left4me/`.** Specifically:
   - `/var/lib/left4me/.venv` (was `/opt/left4me/.venv`)
   - `/var/lib/left4me/steam` (was `/opt/left4me/steam`)
3. **Production install model is non-editable.** ckn-bw's
   `left4me_pip_install` action copies the (root-owned) source to a
   left4me-owned tempdir under `$TMPDIR` and runs
   `pip install --force-reinstall "$tmpdir/l4d2host" "$tmpdir/l4d2web"`
   from there. The tempdir is cleaned by a trap on EXIT.

Local-development install flows are unchanged: developers still use
`pip install -e ./l4d2host -e ./l4d2web` via direnv.

## Why the scope expanded

The original handoff (`2026-05-15-handoff-noneditable-install.md`)
proposed a minimal change: flip `/opt/left4me/src` to root:root and
switch `pip install -e` → `pip install` directly. That spec stated
"Non-editable install works out of the box; no packaging edits needed."

That premise turned out to be wrong. `setuptools.build_meta`'s PEP 517
`get_requires_for_build_wheel` hook runs `setup.py egg_info` in the
source directory by design, and `egg_info` writes `<pkg>.egg-info/`
back to the cwd. Against a root-owned source tree, this fails with
`Permission denied`. `python -m build` was tried as an alternative —
its build isolation only sandboxes build *dependencies*, not the
source, so it hits the same failure.

The fix that actually works is to copy the source to a writable
location and build from the copy. Once that one-shot copy is in the
pip_install action, the original narrow scope becomes inconsistent:
the source is root-owned, the venv is left4me-owned, both live under
`/opt/left4me/`. Moving runtime mutable state out of `/opt/left4me/`
and into `/var/lib/left4me/` resolves the inconsistency by aligning
with FHS conventions: `/opt/<app>` = read-only deploy artifacts,
`/var/lib/<app>` = mutable runtime state.

The operator opted for the larger reshape ("do the best long-term
solution now") rather than landing the narrow change and queuing the
relocation separately.

## What changed concretely

### ckn-bw side (`bundles/left4me/`)

- `items.py`
  - `directory:/opt/left4me` → `root:root 0755` (was `left4me:left4me`)
  - `directory:/opt/left4me/src` → `root:root` (was `left4me:left4me`)
  - `directory:/opt/left4me/steam` **removed**
  - `directory:/var/lib/left4me/steam` **added** (`left4me:left4me`)
  - `action:left4me_chown_src` **deleted** (was the every-apply
    chown-to-left4me self-heal; no longer needed)
  - `action:left4me_install_steamcmd` — paths flipped to
    `/var/lib/left4me/steam`
  - `action:left4me_create_venv`, `left4me_pip_upgrade`,
    `left4me_alembic_upgrade`, `left4me_seed_overlays` — all venv
    paths changed from `/opt/left4me/.venv` to `/var/lib/left4me/.venv`
  - `action:left4me_pip_install` — completely rewritten to use the
    cp-to-tempdir + pip install approach, marked `triggered: True` so
    it only fires on actual code changes (the cp + wheel build is too
    heavy to run on every apply)
  - `git_deploy:/opt/left4me/src` triggers list — added
    `action:left4me_pip_install` (the new wiring); kept
    `alembic_upgrade` as belt-and-braces and `install_left4me_scripts`
- `metadata.py`
  - `left4me-web.service`: `Environment=PATH=` and `ExecStart=` use
    `/var/lib/left4me/.venv`
  - `left4me-workshop-refresh.service`: same
  - `left4me-server@.service` `BindReadOnlyPaths` entry for steamcmd
    → `/var/lib/left4me/steam`
- `files/etc/left4me/host.env.mako`: `LEFT4ME_STEAMCMD` →
  `/var/lib/left4me/steam/steamcmd.sh`
- `README.md`: updated description

### left4me side

- `deploy/files/usr/local/lib/systemd/system/left4me-web.service` —
  reference unit: `PATH=` + `ExecStart=` use `/var/lib/left4me/.venv`
- `deploy/files/usr/local/lib/systemd/system/left4me-workshop-refresh.service`
  — reference unit: `WorkingDirectory=/opt/left4me/src` (was `/opt/left4me`),
  `PATH=` + `ExecStart=` use `/var/lib/left4me/.venv`
- `deploy/scripts/sbin/left4me` wrapper — flask path
- `deploy/tests/test_example_units.py` — PATH + ExecStart assertions
  updated; the assertion previously read `"Environment=PATH=..."` which
  was already broken (the unit has `Environment=HOME=... PATH=...` on
  one line), now reads just `"PATH=..."`
- `deploy/README.md` — paths described
- `l4d2host/tests/test_cli.py` — `LEFT4ME_STEAMCMD` fixture path

### Host transition (one-shot, performed manually during the deploy)

1. `systemctl stop left4me-web.service`
2. `mv /opt/left4me/steam /var/lib/left4me/steam` (atomic same-fs
   rename; running gameserver `BindReadOnlyPaths` bindings keep
   working because they reference inodes, not paths)
3. `rm -rf /opt/left4me/.venv /opt/left4me/wheels`
4. `bw apply -s svc_systemd:left4me-web.service ovh.left4me` —
   creates new venv at `/var/lib/left4me/.venv` and runs pip_upgrade.
   `-s` to skip the web service item so bw doesn't try to start it
   before pip_install has populated the new venv.
5. Manual `pip_install` (the same command the bundle's
   `left4me_pip_install` action runs) to install l4d2host + l4d2web
   non-editably into the new venv.
6. Manual `alembic upgrade head` + `systemctl start left4me-web.service`.
7. Second `bw apply ovh.left4me` to confirm idempotent.

Gameservers (`left4me-server@1`, `@2`) stayed up throughout —
they don't link to the Python venv and their bind mounts survived
the steam dir rename via inode-level binding.

## Verification (six checks, all green)

1. `stat -c '%U:%G %a %n' /opt/left4me /opt/left4me/src
   /var/lib/left4me/.venv /var/lib/left4me/steam` → `/opt/left4me`
   and `/opt/left4me/src` both `root:root 755`; `.venv` and `steam`
   `left4me:left4me`.
2. `pip show l4d2host l4d2web` → `Location:` is
   `/var/lib/left4me/.venv/lib/python3.13/site-packages`, no
   `Editable project location:` line.
3. `systemctl is-active left4me-web.service` → `active`.
4. `alembic current` → `0012_command_history (head)`.
5. Gameserver fresh-restart **deferred** — running instances are
   unaffected (inode-level binds survive the rename); a fresh `bw
   apply` confirms the new unit content has the new bind paths.
   Will validate on the next operator-initiated server restart.
6. Second `bw apply ovh.left4me` → 0 fixed, 0 failed. Idempotent.

## What this does NOT change

- The deployment-responsibility brainstorm
  (`2026-05-15-handoff-deployment-responsibility.md`) — still queued.
  This prereq just makes target-side symlinks into
  `/opt/left4me/src/deploy/files/...` safe by construction
  (left4me cannot rewrite its own hardening profile).
- Sudoers content (still in `deploy/files/etc/sudoers.d/left4me`
  + the verbatim mirror in ckn-bw; consolidation queued).
- `scripts/{libexec,sbin}/` location in left4me — still under
  the repo root; the deployment-responsibility brainstorm decides
  whether to move them into `deploy/scripts/`.
- Hardening drop-ins — still inline in ckn-bw's `systemd/units`
  reactor; whether to move them to `deploy/files/...` is also
  the deployment-responsibility brainstorm's call.

## Pointers

- Original (now-superseded) handoff:
  `docs/superpowers/specs/2026-05-15-handoff-noneditable-install.md`
- Deployment-responsibility brainstorm handoff:
  `docs/superpowers/specs/2026-05-15-handoff-deployment-responsibility.md`
- ckn-bw bundle: `~/Projekte/ckn-bw/bundles/left4me/`