How development mode works

glimpsectl applet run puts your working copy of an applet into the running panel without touching your config. Its logs go to your terminal, and Ctrl C puts the panel back as it was. The steps are in Develop with live reload.

What happens

1. In a project directory with a justfile, glimpsectl runs just build and attaches the desktop entry the build put in dist/. Without a justfile it attaches the entry in the directory itself.
2. It calls Attach on the panel's applet host over D-Bus, passing the entry, the options and env from devconfig.toml, and its own stderr.
3. The panel checks the entry like an installed one and starts it as a systemd unit. If that bar already shows the applet, in any zone, your copy takes its place there and the installed copy stops; --zone is then ignored. Otherwise your copy goes into the zone you pass with --zone (just dev passes left), the zone your config gives the applet, or the right zone.
4. Your applet's stderr is the terminal, not the journal. A development copy that crashes stays down until you save a file or type r.
5. Ctrl C calls Detach. The panel stops your copy and starts the installed one again. Closing the terminal does the same, because the panel watches the caller on the bus.

What --dev watches

You change	What happens
A source file	just build, then Restart. A failed build keeps the running copy.
options in devconfig.toml	SetOptions: the applet gets an options message and keeps running.
env in devconfig.toml, or the desktop entry	Detach and Attach again with the new entry.

Changes settle for 300 ms first. Hidden paths, node_modules, build, dist and target are not watched. Type r and Enter to build and restart by hand, or t and Enter to print the widget tree the panel holds.

--isolated starts a separate test panel and attaches to it, so the session bar stays untouched. The host takes at most 8 development copies per caller and 16 in total.