• docs: add Commet client guide

- Add docs/configuring-playbook-client-commet.md with configuration, build-version note, install, and troubleshooting
  - Link Commet docs from README.md and docs/configuring-playbook.md

README.md

@@ -64,9 +64,9 @@ Web clients for Matrix that you can host on your own domains.
 | [Element Web](https://github.com/element-hq/element-web) | ✅ | Default Matrix web client, configured to connect to your own Synapse server | [Link](docs/configuring-playbook-client-element-web.md) |
 | [Hydrogen](https://github.com/element-hq/hydrogen-web) | ❌ | Lightweight Matrix client with legacy and mobile browser support | [Link](docs/configuring-playbook-client-hydrogen.md) |
 | [Cinny](https://github.com/ajbura/cinny) |  ❌ | Simple, elegant and secure web client | [Link](docs/configuring-playbook-client-cinny.md) |
-| [Sable](https://github.com/7w1/sable) | ❌ | Simple, elegant and secure web client | [Link](docs/configuring-playbook-client-sable.md) |
 | [SchildiChat Web](https://schildi.chat/) | ❌ | Based on Element Web, with a more traditional instant messaging experience | [Link](docs/configuring-playbook-client-schildichat-web.md) |
 | [FluffyChat Web](https://fluffychat.im/) | ❌ | The cutest messenger in Matrix | [Link](docs/configuring-playbook-client-fluffychat-web.md) |
+| [Commet](https://github.com/commetchat/commet) | ❌ | Matrix web client | [Link](docs/configuring-playbook-client-commet.md) |
 
 ### Server Components
 
@@ -75,12 +75,13 @@ Services that run on the server to make the various parts of your installation w
 | Name | Default? | Description | Documentation |
 | ---- | -------- | ----------- | ------------- |
 | [PostgreSQL](https://www.postgresql.org/)| ✅ | Database for Synapse. [Using an external PostgreSQL server](docs/configuring-playbook-external-postgres.md) is also possible. | [Link](docs/configuring-playbook-external-postgres.md) |
+| [coturn](https://github.com/coturn/coturn) | ❌ | STUN/TURN server for WebRTC audio/video calls | [Link](docs/configuring-playbook-turn.md) |
 | [Traefik](https://doc.traefik.io/traefik/) | ✅ | Web server, listening on ports 80, 443 and 8448 - standing in front of all the other services. [Using your own webserver](docs/configuring-playbook-own-webserver.md) is also possible. | [Link](docs/configuring-playbook-traefik.md) |
 | [Let's Encrypt](https://letsencrypt.org/) | ✅ | Free SSL certificate, which secures the connection to all components | [Link](docs/configuring-playbook-ssl-certificates.md) |
 | [Exim](https://www.exim.org/) | ✅ | Mail server, through which all Matrix services send outgoing email (can be configured to relay through another SMTP server) | [Link](docs/configuring-playbook-email.md) |
-| [coturn](https://github.com/coturn/coturn) | ❌ | STUN/TURN server for WebRTC audio/video calls | [Link](docs/configuring-playbook-turn.md) |
 | [ddclient](https://github.com/linuxserver/docker-ddclient) | ❌ | Dynamic DNS | [Link](docs/configuring-playbook-dynamic-dns.md) |
-| Matrix RTC stack | ❌ | Supporting components ([LiveKit Server](docs/configuring-playbook-livekit-server.md) and [LiveKit JWT Service](docs/configuring-playbook-livekit-jwt-service.md)) for in-app audio/video calls for Matrix clients | [Link](docs/configuring-playbook-matrix-rtc.md) |
+| [LiveKit Server](https://github.com/livekit/livekit) | ❌ | WebRTC server for audio/video calls | [Link](docs/configuring-playbook-livekit-server.md) |
+| [Livekit JWT Service](https://github.com/livekit/livekit-jwt-service) | ❌ | JWT service for integrating [Element Call](./configuring-playbook-element-call.md) with [LiveKit Server](./configuring-playbook-livekit-server.md) | [Link](docs/configuring-playbook-livekit-jwt-service.md) |
 
 ### Authentication
 

docs/configuring-playbook-client-commet.md

@@ -0,0 +1,93 @@
+<!--
+SPDX-FileCopyrightText: 2026 MDAD project contributors
+
+SPDX-License-Identifier: AGPL-3.0-or-later
+-->
+
+# Setting up Commet (optional)
+
+The playbook can install and configure the [Commet](https://github.com/commetchat/commet) Matrix web client for you.
+
+## Adjusting DNS records
+
+By default, this playbook installs Commet on the `commet.` subdomain (`commet.example.com`) and requires you to create a CNAME record for `commet`, which targets `matrix.example.com`.
+
+When setting, replace `example.com` with your own.
+
+## Adjusting the playbook configuration
+
+To enable Commet, add the following configuration to your `inventory/host_vars/matrix.example.com/vars.yml` file:
+
+```yaml
+matrix_client_commet_enabled: true
+```
+
+### Adjusting the Commet URL (optional)
+
+By tweaking the `matrix_client_commet_hostname` and `matrix_client_commet_path_prefix` variables, you can easily make the service available at a **different hostname and/or path** than the default one.
+
+Example additional configuration for your `vars.yml` file:
+
+```yaml
+# Switch to the domain used for Matrix services (`matrix.example.com`),
+# so we won't need to add additional DNS records for Commet.
+matrix_client_commet_hostname: "{{ matrix_server_fqn_matrix }}"
+
+# Expose under the /commet subpath
+matrix_client_commet_path_prefix: /commet
+```
+
+After changing the domain, **you may need to adjust your DNS** records to point the Commet domain to the Matrix server.
+
+If you've decided to reuse the `matrix.` domain, you won't need to do any extra DNS configuration.
+
+**Note**: `matrix_client_commet_path_prefix` must either be `/` or not end with a slash (e.g. `/commet`).
+
+### Adjusting the default homeserver (optional)
+
+Commet is configured with a `default_homeserver` value. By default, the playbook uses `matrix.org`.
+
+To change it, add the following configuration to your `vars.yml` file:
+
+```yaml
+matrix_client_commet_default_homeserver: "{{ matrix_domain }}"
+```
+
+### Adjusting the Commet version/branch to build (optional)
+
+When self-building the container image (`matrix_client_commet_container_image_self_build: true`), the playbook checks out the Commet source repository and builds an image from it.
+
+To build from a different git branch/tag/SHA, set `matrix_client_commet_version` in your `vars.yml` file:
+
+```yaml
+# Examples: "main", "v1.2.3", "feature-branch", "a1b2c3d4"
+matrix_client_commet_version: "main"
+```
+
+**Note**: by default, the image tag is derived from `matrix_client_commet_version` (`localhost/matrix-client-commet:{{ matrix_client_commet_version }}`). If your branch name contains `/` (e.g. `feature/foo`), override `matrix_client_commet_container_image` (and optionally `matrix_client_commet_container_image_self_build_version_tag`) to a Docker-tag-safe value.
+
+### Extending the configuration
+
+There are some additional things you may wish to configure about the component.
+
+Take a look at:
+
+- `roles/custom/matrix-client-commet/defaults/main.yml` for some variables that you can customize via your `vars.yml` file
+- `roles/custom/matrix-client-commet/templates/global_config.json.j2` for the component's default runtime configuration
+
+## Installing
+
+After configuring the playbook and potentially [adjusting your DNS records](#adjusting-dns-records), run the playbook with [playbook tags](playbook-tags.md) as below:
+
+<!-- NOTE: let this conservative command run (instead of install-all) to make it clear that failure of the command means something is clearly broken. -->
+```sh
+ansible-playbook -i inventory/hosts setup.yml --tags=setup-all,start
+```
+
+The shortcut commands with the [`just` program](just.md) are also available: `just install-all` or `just setup-all`
+
+`just install-all` is useful for maintaining your setup quickly ([2x-5x faster](../CHANGELOG.md#2x-5x-performance-improvements-in-playbook-runtime) than `just setup-all`) when its components remain unchanged. If you adjust your `vars.yml` to remove other components, you'd need to run `just setup-all`, or these components will still remain installed. Note these shortcuts run the `ensure-matrix-users-created` tag too.
+
+## Troubleshooting
+
+As with all other services, you can find the logs in [systemd-journald](https://www.freedesktop.org/software/systemd/man/systemd-journald.service.html) by logging in to the server with SSH and running `journalctl -fu matrix-client-commet`.