Gnome Shell Extension Local Dev

GNOME Shell Extension Local Dev (GNOME 46–50)

When to use

Creating, iterating on, or packaging a GNOME Shell extension. Covers project structure, import paths, gettext, threading, live install/enable, debugging, and CI packaging.

Project structure (GNOME 50 verified)

<uuid>@<domain>/
  metadata.json          # uuid, name, shell-version[], version (int), version-name (str), settings-schema, gettext-domain
  extension.js           # import { Extension, gettext as _ } from 'resource:///org/gnome/shell/extensions/extension.js'
  prefs.js               # import { ExtensionPreferences } from 'resource:///org/gnome/Shell/Extensions/js/extensions/prefs.js'
  codeburn.js (etc)      # helper modules — receive gettext as a parameter, never import it
  stylesheet.css
  schemas/<schema>.gschema.xml
  install.sh             # symlink/enable/reload script (pure bash)
  Makefile               # install/link/uninstall/schemas targets
  .gitlab-ci.yml         # pack/validate/upload/release pipeline

UUID format: name@domain.tld. The extension dir name MUST equal the uuid.

Import paths (critical — getting either wrong silently breaks loading)

• extension.js: import { Extension, gettext as _ } from 'resource:///org/gnome/shell/extensions/extension.js' (lowercase shell)
• prefs.js: import { ExtensionPreferences } from 'resource:///org/gnome/Shell/Extensions/js/extensions/prefs.js' (capital Shell/Extensions, different path js/extensions/prefs.js)
• helper modules: do NOT import gettext. Receive it as a constructor/method parameter from extension.js.

gettext (GNOME 45+ ESM)

• gettext from extension.js can ONLY be called while an extension's code is executing
• Calling _() at module-import time (top-level const, helper module import) throws Error: gettext can only be called from extensions → extension fails to load (state INITIALIZED, stuck in error, indicator never appears)
• Correct pattern: in extension.js, pass _ (the module-level import) into helper constructors: new MyIndicator(settings, _). Helpers store as this._ and call this._('...') only inside method bodies (render/init time)
• In prefs.js, use this.gettext.bind(this) as a local _ inside fillPreferencesWindow
• Add gettext-domain to metadata.json
• Debug: gdbus call --session --dest org.gnome.Shell.Extensions --object-path /org/gnome/Shell/Extensions --method org.gnome.Shell.Extensions.GetExtensionErrors <uuid>

Threading (GJS)

• GLib.Thread.try_new() is NOT introspectable in GJS — throws immediately
• Use GLib.idle_add(GLib.PRIORITY_DEFAULT_IDLE, () => { ... return GLib.SOURCE_REMOVE; }) for synchronous spawns that take ~1s
• The shell tolerates a brief block at idle priority

GObject signals

• Declare in registerClass: GObject.registerClass({ Signals: { 'my-signal': {} } }, class ...)
• Emit with matching arg count: this.emit('my-signal') for 0-arg signals
• emit('my-signal', null) on a 0-arg signal throws Signal requires 0 args got 1

Install for live editing (symlink)

UUID=name@domain.tld
EXT=~/.local/share/gnome-shell/extensions/$UUID
ln -sfn "$PWD" "$EXT"
# compile schema into BOTH the extension's schemas/ dir AND the user schemas dir
glib-compile-schemas --strict --targetdir=schemas schemas
cp schemas/gschemas.compiled ~/.local/share/glib-2.0/schemas/gschemas.compiled

glib-compile-schemas not on PATH (NixOS)

GLIB_CS=$(command -v glib-compile-schemas || ls /nix/store/*-glib-*-dev/bin/glib-compile-schemas | head -1)

Enable + reload via DBus

# DBus interface: org.gnome.Shell.Extensions at /org/gnome/Shell/Extensions
gdbus call --session --dest org.gnome.Shell.Extensions \
  --object-path /org/gnome/Shell/Extensions \
  --method org.gnome.Shell.Extensions.EnableExtension <uuid>
gdbus call --session --dest org.gnome.Shell.Extensions \
  --object-path /org/gnome/Shell/Extensions \
  --method org.gnome.Shell.Extensions.GetExtensionInfo <uuid>

• EnableExtension returns (true,) for known extensions, (false,) for unknown
• GetExtensionInfo returns (@a{sv} {},) (empty dict) for unknown extensions
• ReloadExtension is NOT implemented on GNOME 50.2

Shell scan limitation (Wayland)

• GNOME Shell scans ~/.local/share/gnome-shell/extensions only at startup
• No DBus method triggers a fresh scan
• A freshly symlinked extension needs a one-time shell restart (log out/in)
• After first scan, DisableExtension + EnableExtension can toggle live
• ReloadExtension not implemented → code edits also need restart on GNOME 50.2
• Pre-add uuid to enabled-extensions gsettings so it auto-enables on next login

UninstallExtension DANGER

• UninstallExtension DBus method (and gnome-extensions uninstall) FOLLOWS SYMLINKS
• On a symlinked extension, it recursively deletes the REAL source directory including .git
• NEVER call UninstallExtension on a symlinked extension
• To remove: rm ~/.local/share/gnome-shell/extensions/<uuid> (removes symlink only)

gsettings enabled-extensions (pure bash)

# Parse GLib variant text: ['a','b'] or @as []
parse() { gsettings get org.gnome.shell enabled-extensions | sed "s/^@\w\+\s*\[//; s/^\[//; s/\]$//; s/'//g; s/, /\n/g" | sed '/^$/d'; }
# Rebuild: ['a','b']
join() { local items=() line; while IFS= read -r line || [[ -n "$line" ]]; do [[ -z "$line" ]] && continue; items+=("'$line'"); done; local j; j="$(IFS=,; printf '%s' "${items[*]}")"; printf '[%s]' "$j"; }
# Append idempotent
add() { local list; list="$(parse)"; printf '%s\n' "${list}" | grep -qxF "$UUID" && return 0; gsettings set org.gnome.shell enabled-extensions "$(printf '%s\n%s\n' "${list}" "$UUID" | join)"; }

Debugging

# Check extension state and errors
gdbus call --session --dest org.gnome.Shell.Extensions \
  --object-path /org/gnome/Shell/Extensions \
  --method org.gnome.Shell.Extensions.GetExtensionErrors <uuid>
gdbus call --session --dest org.gnome.Shell.Extensions \
  --object-path /org/gnome/Shell/Extensions \
  --method org.gnome.Shell.Extensions.GetExtensionInfo <uuid>
# Check journal for stack traces
journalctl --user -b | grep -i "codeburn\|<uuid>" | tail -20

Packaging (CI)

• gnome-extensions pack segfaults in Fedora 41 CI. Use manual zip:

mkdir -p dist/staging/schemas
cp metadata.json extension.js prefs.js *.js stylesheet.css dist/staging/
cp schemas/*.gschema.xml schemas/gschemas.compiled dist/staging/schemas/
cd dist/staging && zip -r ../<uuid>.shell-extension.zip . && cd ../..

• gnome-extensions pack --extra-source=<file> is needed for helper modules (codeburn.js, ui.js) — without it they're omitted from the zip
• ZIP structure: files at archive root, schemas/ subdir — no top-level directory wrapper

CI gotchas

• [skip ci] in commit messages permanently poisons the tag — GitLab skips ALL pipelines for that commit. Use workflow:rules with $CI_COMMIT_MESSAGE =~ /^release:.*/ + when: never instead
• CI_REPOSITORY_URL embeds the CI token (gitlab-ci-token:[MASKED]@...). Use CI_PROJECT_URL for constructing push URLs
• python3 not available in before_script on Fedora 41 (before dnf install). Use sed for file patching
• YAML colons in script strings break parsing. Use | block scalars for lines containing : followed by text