Add Flex Taskbar plugin

[sudiptacmd]

Plugin

• Id: sudiptacmd/flex-taskbar
• New plugin
• Update to an existing plugin (version bumped in plugin.toml)

What it does

Adds a configurable Niri taskbar to the Noctalia bar. It supports pinned and unpinned running apps, grouped windows, one indicator dot per window, a focused-window dot and underline, focus/cycle/launch interactions, output filtering, full visual customization, and clickable window thumbnails on hover.

Icons default to 100% opacity in every state, and the per-item hover background defaults to transparent.

External dependencies

• niri: query windows/workspaces, focus windows, and capture preview thumbnails.
• gtk-launch: launch pinned desktop-file IDs without a custom command.
• wl-copy and wl-paste: preserve and restore clipboard data around Niri's screenshot action.
• head: select the first available clipboard MIME type.
• rm: remove the temporary clipboard backup.
• User-configured custom launch commands are executed as the current user.

There are no network calls. Preview PNGs and a temporary clipboard backup are written only under noctalia.pluginDataDir().

Testing

• Tested on Niri
• Tested on Hyprland
• Tested on Sway
• Tested on another compositor:
• Noctalia version tested against: 5.0.0
• Plugin API level: 15

Validated locally with:

• noctalia plugins lint flex-taskbar — 0 errors, 0 warnings.
• python3 .github/workflows/scripts/validate-plugins.py — 77 manifests validated.
• python3 -m unittest discover -s .github/workflows/scripts -p 'test_*.py' — 56 tests passed.
• Live Niri testing covered app launch/focus/cycling, per-window dots, focused underline, IPC refresh/settings/preview/close events, preview capture, clickable preview focus, disabling previews, 100% icon opacity, and transparent widget hover.

Screenshots / Videos

Running taskbar:

Store thumbnail:

Checklist

• The directory name matches the part of id after the / in plugin.toml exactly.
• It ships plugin.toml, README.md, thumbnail.webp, and translations/en.json.
• README.md follows the
  README template, documents
  every entry id and dependency, and includes exact panel IPC commands and launcher prefixes where applicable.
• I created thumbnail.webp with the thumbnail generator.
• version follows semver and is bumped in this PR; plugin_api is the oldest API level this plugin requires.
• Every non-English translation in this PR uses a locale supported by Noctalia core, and I can read, write, and
  understand that language well enough to review and maintain it (no unreviewed machine/LLM translations).
• I did not edit catalog.toml; CI generates it.
• This PR touches exactly one plugin directory.

Code review attestation

Plugins run as trusted, unsandboxed Luau in the user's session. Confirm:

• The code is readable and not obfuscated, minified, or generated.
• It does not download and execute remote code.
• Every network call, filesystem write, and spawned process is something the description above accounts for.
• I have the right to publish this code under the license declared in plugin.toml.