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mesh-catalog/modules/picom/README.md
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mesh-tools 652b00b25b
mesh/merge-gate checking again: the gate refused `unknown` because the controller judged with a node-engine validator pinned before mesh-host #117; mesh-co…
mesh/repo-check checking again: the gate refused `unknown` because the controller judged with a node-engine validator pinned before mesh-host #117; mesh-co…
mesh/delivery-group group feat/owned-paths checking: 0 of 2 member(s) ready
mesh/delivery superseded: a newer head of the same pull request
Say on every directory how it treats files it does not know, and check it (issue 1024, ADR 0422)
Every directory and archive resource carries `unknown`: move-out for a home folder whose program writes nothing there (the node-engine, delivered in mesh-host #117, moves the rest to ~/.local/state/mesh-moved/<module>/ with a list), module for ~/.ssh and ~/.claude, program elsewhere; `knows` keeps what a program or the operator relies on (powerlevel10k's compiled files, i3's scripts and the asus/g14 drop-ins, dunst's slack rule, betterbird's records, node-env's forge credential, issue 1033). Two shared folders are no longer declared. Each module's README says it. checks/owned holds every manifest to it; checks/sshdir stays while main's merge check runs it (issue 1035). Tests that pin a manifest follow the new key only. Reviewed in three rounds.
2026-10-17 16:23:03 +00:00

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Markdown

# picom
The X compositor as a module (novox/hq ADR 0208, research 026).
- Installs `picom`, and `xorg-xprop` for setting a window's own opacity.
- Claims the mesh's `node-compositor` seat (no verbs yet, ADR 0208 §2) and requires `x11-display`.
That requirement has the machine's reach: the display server must be held on this module's own
machine, or assignment is refused, naming the seat's holders.
- Owns `~/.config/picom/` and `~/.config/picom/picom.conf`, which it writes whole at every push.
- **Adds no start of its own.** picom's package ships an XDG autostart entry
(`/etc/xdg/autostart/picom.desktop`), which the session runs: the `i3` module's `dex --autostart`.
That is the tool's own grain (ADR 0208 §4) and its one start. The desktop modules follow one rule:
a process has one starter. Its package's autostart entry is that starter where there is one, and
the `xinitrc` slot where there is none.
## Settings
Two preferences, each a machine's own (the per-node layer of `settings`), because the right values follow
the machine's graphics driver (novox/hq research 037):
| setting | default | what it changes |
|---|---|---|
| `backend` | `glx` | how picom draws: `glx` on the graphics card, `xrender` on the CPU |
| `use-damage` | `true` | `true` repaints only what changed (picom's own default); `false` repaints the whole screen each frame |
The defaults are what every machine ran before, so the file filled with them changes nothing. They exist
for hq issue 345: a window that is mapped but shows nothing (a calendar reminder) or stays stale after a
workspace switch (a chat window) is a known failure of glx with damage tracking on some drivers, and
`xrender` or `use-damage` false is how a machine is set to test that. The file stays trusted, so both are set at the
controller's terminal alone (issue 339): a value is pasted into picom.conf as it is, and a backend of
`xrender"; write-pid-path = "…` would add an option of the caller's (hq issue 346). A changed file is read at
the next `picom_restart` or login: the module has no unit to reload.
## Tools
Served by the node's runtime as the operator account (ADR 0175). The tools find the operator's X
session from the window manager's own environment, and say so plainly when nobody is logged in.
| tool | does |
|---|---|
| `picom_restart` | a running picom re-reads its file (`SIGUSR1`); `hard`, or none running, starts a fresh one |
| `picom_rules` | the global options and the window rules in force, in picom's order, and whether it runs |
| `picom_window_opacity` | read or set one window's own opacity, the focused window by default |
| `picom_toggle` | compositing off or on, for a game or a test; the next login starts it again |
A picom a tool starts runs under the account's own service manager (`systemd-run --user`, unit
`picom`). As a child of the runtime it would die whenever the runtime restarts.
## What it improves on what was found
- **Window rules** replace `opacity-rule`, `inactive-opacity` and `inactive-dim`, which picom 12 and
later supersede. The behaviour is the same: only terminals are translucent (95 % focused, 75 %
unfocused). The browser and video "pin to 100 %" rule went, because nothing else is made
translucent any more.
- **Full-screen windows are opaque,** a terminal included.
- **One start.** Today both the window manager's configuration and the autostart entry start picom,
and the second one exits.
- On the desktop, picom was not running at all on the day it was measured, although both starts were
in place. It probably fails to start on that machine's GPU. `picom_restart` with `hard` after
assignment answers with what happened. The next step is the `picom` user unit's journal.
## What lies outside its directory
The window manager's own `exec --no-startup-id picom` line belongs to the `i3` module's configuration,
which no longer carries it. Nothing else of picom's lies outside the directory this module owns.
## Migration (ADR 0182)
- The first push keeps the found `picom.conf` once, then writes the module's.
- Until the `i3` module replaces the hand-kept `~/.config/i3/config`, its `exec picom` line starts a
second picom. The second one exits at once, because a compositor is already running. Nothing to
do, unless the line is still there after `i3` is assigned.
## Blockers
- The seat `node-compositor` and the provision `x11-display` are ADR 0208's.
Until the controller knows them, `mctl` reads the claim and the requirement as unknown, and refuses
the module.
- `xorg-xprop` is declared here because the `xorg` module does not install it. If `xorg` comes to
declare it, it leaves this module, since a package is declared once per node.
## Files it does not know
Each directory or archive this module declares says how it treats a file it did not write (ADR 0422, ADR 0416).
- `~/.config/picom`: holds only what this module declares; anything else is moved out by the node-engine to `~/.local/state/mesh-moved/picom/` with a list, never deleted (ADR 0422 §4).