When a Quadlet unit file already exists for an orchestrator-managed
backend, sync its on-disk bytes against what the current renderer
produces. write_if_changed makes this idempotent — when bytes match,
no IO; when they differ (post-deploy of a renderer change), the file
is rewritten and systemctl --user daemon-reload runs once.
We deliberately do NOT restart the .service when the file changes:
running containers keep their current config until the operator
restarts them. That's the right tradeoff — file updates are cheap and
non-destructive; service restarts are the SIGKILL cascade we're
trying to eliminate.
Why this matters: pre-this-commit, every renderer change required a
fresh package.install RPC per app to take effect. Observed live on
.228 2026-05-02 — the TimeoutStartSec=600 fix shipped in code but
existing units stayed on the old format because nothing triggered a
re-render. Combined with state.json being empty (so the reconciler's
auto-install path didn't fire either), the fix was invisible until
manual unit deletion.
Companions (UI_APP_IDS) are skipped — companion.rs renders those units
with a different shape; syncing here would clobber them.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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