Refactor dev services to support homeserver choice (Continuwuity or Synapse)

The dev environment previously hardcoded Synapse (bundled with Postgres
and Element Web) in a monolithic etc/services/core/ directory.

With Continuwuity now available as a lighter alternative (no external DB),
this refactors the service layout so developers choose their homeserver
once and everything derives from that choice. Continuwuity is the new
default for its smaller footprint.

Key changes:
- Break etc/services/core/ into etc/services/synapse/ and
  etc/services/element-web/, each with their own compose.yml
- Add `homeserver` variable in justfile (reads var/homeserver,
  defaults to continuwuity)
- Add `homeserver-init` recipe to persist the choice
- Use placeholders (__HOMESERVER_SERVER_NAME__, __HOMESERVER_URL__,
  __HOMESERVER_CLIENT_URL__) in config templates, resolved at
  prepare time based on the chosen homeserver
- Make services-start/stop/prepare/tail-logs delegate to the chosen
  homeserver's recipes + element-web
- Make users-prepare delegate to {homeserver}-users-prepare
- Update docs/development.md for the new homeserver choice flow

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/development.md

@@ -18,6 +18,27 @@ For local development, we run all dependency services in [🐋 Docker](https://w
 - (Optional) an API key for some Large Language Model [☁️ provider](./providers.md) (e.g. [OpenAI](./providers.md#openai)), though we recommend using [LocalAI](#localai) or [Ollama](#ollama) for local development
 
 
+### Choosing a homeserver
+
+The development environment supports two homeserver implementations:
+
+- **[Continuwuity](https://continuwuity.org/)** (default) — lightweight, no external database required. Good for most development needs.
+- **[Synapse](https://github.com/element-hq/synapse)** — the reference implementation, bundled with Postgres. Use this if you need Synapse-specific behavior.
+
+To choose a homeserver (optional — defaults to Continuwuity if skipped):
+
+```sh
+just homeserver-init continuwuity  # or: just homeserver-init synapse
+```
+
+The choice is stored in `var/homeserver` and affects all subsequent commands.
+
+> **Note:** If you switch homeservers after initial setup, you will need to:
+> - Delete `var/app/local/` and/or `var/app/container/` (app config and data)
+> - Delete `var/services/element-web/` (to regenerate its config)
+> - Re-run the prepare and user registration steps
+
+
 ### Getting started guide
 
 Developing [locally](#running-locally) is possible, but requires a [Rust](https://www.rust-lang.org/) toolchain.
@@ -28,11 +49,12 @@ In any case, you will need [🐋 Docker](https://www.docker.com/) as [dependency
 
 #### Running locally
 
-1. Start the core dependency services (Postgres, Synapse, Element Web): `just services-start`
-2. (Only the first time around) Prepare initial app configuration in `var/app/local/config.yml`: `just app-local-prepare`
-3. (Only the first time around) [Prepare your configuration file](#prepare-your-configuration-file)
-4. (Only the first time around) Prepare initial default Matrix user accounts (`admin` and `baibot`): `just users-prepare`
-5. (Optional) Start additional services depending on which [agent provider you've chosen](#choosing-an-agent-provider):
+1. (Optional) Choose a homeserver: `just homeserver-init continuwuity` (or `synapse`). Default is `continuwuity`.
+2. Start the homeserver and Element Web: `just services-start`
+3. (Only the first time around) Prepare initial app configuration in `var/app/local/config.yml`: `just app-local-prepare`
+4. (Only the first time around) [Prepare your configuration file](#prepare-your-configuration-file)
+5. (Only the first time around) Prepare initial default Matrix user accounts (`admin` and `baibot`): `just users-prepare`
+6. (Optional) Start additional services depending on which [agent provider you've chosen](#choosing-an-agent-provider):
   - for [LocalAI](#localai):
     - Start services: `just localai-start`
 	- Wait a while for LocalAI to start up. It has a lot of models to download. Monitor progress using `just localai-tail-logs`
@@ -40,12 +62,12 @@ In any case, you will need [🐋 Docker](https://www.docker.com/) as [dependency
   - for [Ollama](#ollama):
     - Start services: `just ollama-start`
     - (Only the first time around) Pull the model configured in `agents.static_definitions` in the configuration file: `just ollama-pull-model gemma2:2b`
-6. Start the bot: `just run-locally`
-7. Go to http://element.127.0.0.1.nip.io:42025/ and login with `admin` / `admin`
-8. Create a new room and invite `@baibot:synapse.127.0.0.1.nip.io`
-9. When done, stop the bot (`Ctrl` + `C`)
-10. Stop the core dependency services: `just services-stop`
-11. (Optional) Stop additional services:
+7. Start the bot: `just run-locally`
+8. Go to http://element.127.0.0.1.nip.io:42025/ and login with `admin` / `admin`
+9. Create a new room and invite `@baibot:continuwuity.127.0.0.1.nip.io` (or `@baibot:synapse.127.0.0.1.nip.io` if using Synapse)
+10. When done, stop the bot (`Ctrl` + `C`)
+11. Stop the services: `just services-stop`
+12. (Optional) Stop additional services:
   - for [LocalAI](#localai): `just localai-stop`
   - for [Ollama](#ollama): `just ollama-stop`
 
@@ -54,11 +76,12 @@ In any case, you will need [🐋 Docker](https://www.docker.com/) as [dependency
 
 You can avoid having a [Rust](https://www.rust-lang.org/) toolchain installed locally and build/run this in a container.
 
-1. Start the core dependency services (Postgres, Synapse, Element Web): `just services-start`
-2. (Only the first time around) Prepare initial app configuration in `var/app/container/config.yml`: `just app-container-prepare`
-3. (Only the first time around) [Prepare your configuration file](#prepare-your-configuration-file)
-4. (Only the first time around) Prepare initial default Matrix user accounts (`admin` and `baibot`): `just users-prepare`
-5. (Optional) Start additional services depending on which [agent provider you've chosen](#choosing-an-agent-provider):
+1. (Optional) Choose a homeserver: `just homeserver-init continuwuity` (or `synapse`). Default is `continuwuity`.
+2. Start the homeserver and Element Web: `just services-start`
+3. (Only the first time around) Prepare initial app configuration in `var/app/container/config.yml`: `just app-container-prepare`
+4. (Only the first time around) [Prepare your configuration file](#prepare-your-configuration-file)
+5. (Only the first time around) Prepare initial default Matrix user accounts (`admin` and `baibot`): `just users-prepare`
+6. (Optional) Start additional services depending on which [agent provider you've chosen](#choosing-an-agent-provider):
   - for [LocalAI](#localai):
     - Start services: `just localai-start`
 	- Wait a while for LocalAI to start up. It has a lot of models to download. Monitor progress using `just localai-tail-logs`
@@ -66,12 +89,12 @@ You can avoid having a [Rust](https://www.rust-lang.org/) toolchain installed lo
   - for [Ollama](#ollama):
     - Start services: `just ollama-start`
     - (Only the first time around) Pull the model configured in `agents.static_definitions` in the configuration file: `just ollama-pull-model gemma2:2b`
-6. Start the bot: `just run-in-container`
-7. Go to http://element.127.0.0.1.nip.io:42025/ and login with `admin` / `admin`
-8. Create a new room and invite `@baibot:synapse.127.0.0.1.nip.io`
-9. When done, stop the bot (`Ctrl` + `C`)
-10. Stop the dependency services: `just services-stop`
-11. (Optional) Stop additional services:
+7. Start the bot: `just run-in-container`
+8. Go to http://element.127.0.0.1.nip.io:42025/ and login with `admin` / `admin`
+9. Create a new room and invite `@baibot:continuwuity.127.0.0.1.nip.io` (or `@baibot:synapse.127.0.0.1.nip.io` if using Synapse)
+10. When done, stop the bot (`Ctrl` + `C`)
+11. Stop the services: `just services-stop`
+12. (Optional) Stop additional services:
   - for [LocalAI](#localai): `just localai-stop`
   - for [Ollama](#ollama): `just ollama-stop`
 

etc/app/config.yml.dist

@@ -1,7 +1,7 @@
 homeserver:
   # The canonical homeserver domain name
-  server_name: synapse.127.0.0.1.nip.io
-  url: http://synapse.127.0.0.1.nip.io:42020
+  server_name: __HOMESERVER_SERVER_NAME__
+  url: __HOMESERVER_URL__
 
 user:
   mxid_localpart: baibot
@@ -45,7 +45,7 @@ room:
 access:
   # Space-separated list of MXID patterns which specify who is an admin.
   admin_patterns:
-    - "@admin:synapse.127.0.0.1.nip.io"
+    - "@admin:__HOMESERVER_SERVER_NAME__"
 
 persistence:
   # This is unset here, because we expect the configuration to come from an environment variable (BAIBOT_PERSISTENCE_DATA_DIR_PATH).
@@ -157,7 +157,7 @@ initial_global_config:
   # Space-separated list of MXID patterns which specify who can use the bot.
   # By default, we let anyone on the homeserver use the bot.
   user_patterns:
-    - "@*:synapse.127.0.0.1.nip.io"
+    - "@*:__HOMESERVER_SERVER_NAME__"
 
 # Controls logging.
 #

etc/services/element-web/compose.yml

@@ -0,0 +1,21 @@
+services:
+  element-web:
+    image: ghcr.io/element-hq/element-web:v1.12.9
+    user: "${UID}:${GID}"
+    restart: unless-stopped
+    environment:
+      ELEMENT_WEB_PORT: 8080
+    ports:
+      - "${SERVICE_ELEMENT_WEB_BIND_PORT_HTTP}:8080"
+    volumes:
+    - ./element-web/config.json:/app/config.json:ro
+    tmpfs:
+      - /var/cache/nginx:rw,mode=777
+      - /var/run:rw,mode=777
+      - /tmp/element-web-config:rw,mode=777
+      - /etc/nginx/conf.d:rw,mode=777
+
+networks:
+  default:
+    name: ${NETWORK_NAME}
+    external: true

etc/services/element-web/config.json.dist

@@ -1,5 +1,5 @@
 {
-    "default_hs_url": "http://synapse.127.0.0.1.nip.io:42020",
+    "default_hs_url": "__HOMESERVER_CLIENT_URL__",
     "default_is_url": "https://vector.im",
     "integrations_ui_url": "https://scalar.vector.im/",
     "integrations_rest_url": "https://scalar.vector.im/api",

etc/services/synapse/compose.yml

@@ -23,25 +23,9 @@ services:
     - "${SERVICE_SYNAPSE_BIND_PORT_CLIENT_API}:8008"
     - "${SERVICE_SYNAPSE_BIND_PORT_FEDERATION_API}:8008"
     volumes:
-    - ../../etc/services/core/synapse/config:/config:ro
+    - ../../etc/services/synapse/config:/config:ro
     - ./synapse/media-store:/media-store
 
-  element-web:
-    image: ghcr.io/element-hq/element-web:v1.12.9
-    user: "${UID}:${GID}"
-    restart: unless-stopped
-    environment:
-      ELEMENT_WEB_PORT: 8080
-    ports:
-      - "${SERVICE_ELEMENT_WEB_BIND_PORT_HTTP}:8080"
-    volumes:
-    - ../../etc/services/core/element-web/config.json:/app/config.json:ro
-    tmpfs:
-      - /var/cache/nginx:rw,mode=777
-      - /var/run:rw,mode=777
-      - /tmp/element-web-config:rw,mode=777
-      - /etc/nginx/conf.d:rw,mode=777
-
 networks:
   default:
     name: ${NETWORK_NAME}

justfile

@@ -7,6 +7,8 @@ admin_password := "admin"
 bot_username := "baibot"
 bot_password := "baibot"
 
+homeserver := `cat var/homeserver 2>/dev/null || echo continuwuity`
+
 mise_data_dir := env("MISE_DATA_DIR", justfile_directory() / "var/mise")
 mise_trusted_config_paths := justfile_directory() / "mise.toml"
 
@@ -14,6 +16,19 @@ mise_trusted_config_paths := justfile_directory() / "mise.toml"
 default:
 	@just --list --justfile {{ justfile() }}
 
+# Selects which homeserver implementation to use (continuwuity or synapse)
+homeserver-init value:
+	#!/bin/sh
+	mkdir -p {{ justfile_directory() }}/var
+	echo {{ value }} > {{ justfile_directory() }}/var/homeserver
+	echo ""
+	echo "⚠️  If you had already prepared your app configuration (var/app/local/config.yml or var/app/container/config.yml),"
+	echo "    you will need to update it manually or delete it and re-run the prepare step."
+	echo "    You should also delete var/app/local/data and/or var/app/container/data,"
+	echo "    as old application state is not compatible across homeserver implementations."
+	echo ""
+	echo "⚠️  If Element Web was already prepared, delete var/services/element-web/ to regenerate its config."
+
 # Builds and runs a development binary
 run-locally *extra_args: app-local-prepare
 	RUST_BACKTRACE=1 \
@@ -73,9 +88,13 @@ docker-compose services_type *extra_args:
 	-p {{ project_name }}-{{ services_type }} \
 	{{ extra_args }}
 
-# Runs a docker-compose command against the core services
-docker-compose-core *extra_args:
-	just docker-compose core {{ extra_args }}
+# Runs a docker-compose command against the synapse services
+docker-compose-synapse *extra_args:
+	just docker-compose synapse {{ extra_args }}
+
+# Runs a docker-compose command against the element-web services
+docker-compose-element-web *extra_args:
+	just docker-compose element-web {{ extra_args }}
 
 # Runs a docker-compose command against the localai services
 docker-compose-localai *extra_args:
@@ -89,17 +108,48 @@ docker-compose-ollama *extra_args:
 docker-compose-continuwuity *extra_args:
 	just docker-compose continuwuity {{ extra_args }}
 
-# Runs all core dependency components (in the background)
-services-start: services-prepare (docker-compose-core "up" "-d")
+# Runs the homeserver and Element Web (in the background)
+services-start: services-prepare
+	just -f {{ justfile_directory() }}/justfile {{ homeserver }}-start
+	just -f {{ justfile_directory() }}/justfile element-web-start
 
-# Stops all core dependency components
-services-stop: (docker-compose-core "down")
+# Stops Element Web and the homeserver
+services-stop:
+	just -f {{ justfile_directory() }}/justfile element-web-stop
+	just -f {{ justfile_directory() }}/justfile {{ homeserver }}-stop
 
-# Tails the logs for all running core services
-services-tail-logs: (docker-compose-core "logs" "-f")
+# Tails the logs for the homeserver and Element Web
+services-tail-logs:
+	just -f {{ justfile_directory() }}/justfile {{ homeserver }}-tail-logs
 
-# Prepares the core services for running
-services-prepare: _prepare-var-services-env _prepare-var-services-postgres _prepare-var-services-synapse _prepare-container-network
+# Prepares the homeserver and Element Web for running
+services-prepare:
+	just -f {{ justfile_directory() }}/justfile {{ homeserver }}-prepare
+	just -f {{ justfile_directory() }}/justfile element-web-prepare
+
+# Runs Synapse (in the background)
+synapse-start: synapse-prepare (docker-compose-synapse "up" "-d")
+
+# Stops Synapse
+synapse-stop: (docker-compose-synapse "down")
+
+# Tails the logs for Synapse
+synapse-tail-logs: (docker-compose-synapse "logs" "-f")
+
+# Prepares Synapse for running
+synapse-prepare: _prepare-var-services-env _prepare-var-services-postgres _prepare-var-services-synapse _prepare-container-network
+
+# Runs Element Web (in the background)
+element-web-start: element-web-prepare (docker-compose-element-web "up" "-d")
+
+# Stops Element Web
+element-web-stop: (docker-compose-element-web "down")
+
+# Tails the logs for Element Web
+element-web-tail-logs: (docker-compose-element-web "logs" "-f")
+
+# Prepares Element Web for running
+element-web-prepare: _prepare-var-services-env _prepare-var-services-element-web _prepare-container-network
 
 # Runs LocalAI (in the background)
 localai-start: localai-prepare (docker-compose-localai "up" "-d")
@@ -142,7 +192,7 @@ continuwuity-register-user username password:
 	{{ justfile_directory() }}/etc/services/continuwuity/register-user.sh {{ justfile_directory() }}/var/services/env {{ username }} {{ password }}
 
 # Prepares the Continuwuity user accounts
-continuwuity-users-prepare:
+continuwuity-users-prepare: continuwuity-prepare
 	just -f {{ justfile_directory() }}/justfile continuwuity-register-user "{{ admin_username }}" "{{ admin_password }}"
 	just -f {{ justfile_directory() }}/justfile continuwuity-register-user "{{ bot_username }}" "{{ bot_password }}"
 
@@ -159,16 +209,20 @@ app-local-prepare: _prepare-var-app-local-config_yml _prepare-var-app-local-data
 app-container-prepare: _prepare-var-app-container-config_yml _prepare-var-app-container-data
 
 # Prepares the user accounts
-users-prepare: services-prepare
+users-prepare:
+	just -f {{ justfile_directory() }}/justfile {{ homeserver }}-users-prepare
+
+# Prepares the Synapse user accounts
+synapse-users-prepare: synapse-prepare
 	just -f {{ justfile_directory() }}/justfile synapse-register-admin-user "{{ admin_username }}" "{{ admin_password }}"
 	just -f {{ justfile_directory() }}/justfile synapse-register-regular-user "{{ bot_username }}" "{{ bot_password }}"
 
 # Starts a Postgres CLI (psql)
-postgres-cli: services-prepare (docker-compose-core "exec" "postgres" "/bin/sh" "-c" "'PGUSER=synapse PGPASSWORD=synapse-password PGDATABASE=homeserver psql -h postgres'")
+postgres-cli: synapse-prepare (docker-compose-synapse "exec" "postgres" "/bin/sh" "-c" "'PGUSER=synapse PGPASSWORD=synapse-password PGDATABASE=homeserver psql -h postgres'")
 
-# Creates an administrator user
-synapse-register-admin-user username password: services-prepare
-	just -f {{ justfile_directory() }}/justfile docker-compose-core \
+# Creates an administrator user on Synapse
+synapse-register-admin-user username password: synapse-prepare
+	just -f {{ justfile_directory() }}/justfile docker-compose-synapse \
 		exec synapse \
 		register_new_matrix_user \
 		--admin \
@@ -177,9 +231,9 @@ synapse-register-admin-user username password: services-prepare
 		-c /config/homeserver.yaml \
 		http://localhost:8008
 
-# Create a regular user
-synapse-register-regular-user username password: services-prepare
-	just -f {{ justfile_directory() }}/justfile docker-compose-core \
+# Creates a regular user on Synapse
+synapse-register-regular-user username password: synapse-prepare
+	just -f {{ justfile_directory() }}/justfile docker-compose-synapse \
 		exec synapse \
 		register_new_matrix_user \
 		--no-admin \
@@ -259,6 +313,22 @@ _prepare-var-services-synapse:
 		mkdir -p var/services/synapse/media-store
 	fi
 
+_prepare-var-services-element-web:
+	#!/bin/sh
+	cd {{ justfile_directory() }};
+
+	if [ ! -f var/services/element-web/config.json ]; then
+		mkdir -p var/services/element-web
+		cp {{ justfile_directory() }}/etc/services/element-web/config.json.dist var/services/element-web/config.json
+
+		homeserver="{{ homeserver }}"
+		if [ "$homeserver" = "continuwuity" ]; then
+			sed --in-place 's|__HOMESERVER_CLIENT_URL__|http://continuwuity.127.0.0.1.nip.io:42030|g' var/services/element-web/config.json
+		elif [ "$homeserver" = "synapse" ]; then
+			sed --in-place 's|__HOMESERVER_CLIENT_URL__|http://synapse.127.0.0.1.nip.io:42020|g' var/services/element-web/config.json
+		fi
+	fi
+
 _prepare-var-services-ollama:
 	#!/bin/sh
 	cd {{ justfile_directory() }};
@@ -298,6 +368,15 @@ _prepare-var-app-local-config_yml:
 	if [ ! -f var/app/local/config.yml ]; then
 		mkdir -p var/app/local
 		cp {{ justfile_directory() }}/etc/app/config.yml.dist var/app/local/config.yml
+
+		homeserver="{{ homeserver }}"
+		if [ "$homeserver" = "continuwuity" ]; then
+			sed --in-place 's/__HOMESERVER_SERVER_NAME__/continuwuity.127.0.0.1.nip.io/g' var/app/local/config.yml
+			sed --in-place 's|__HOMESERVER_URL__|http://continuwuity.127.0.0.1.nip.io:42030|g' var/app/local/config.yml
+		elif [ "$homeserver" = "synapse" ]; then
+			sed --in-place 's/__HOMESERVER_SERVER_NAME__/synapse.127.0.0.1.nip.io/g' var/app/local/config.yml
+			sed --in-place 's|__HOMESERVER_URL__|http://synapse.127.0.0.1.nip.io:42020|g' var/app/local/config.yml
+		fi
 	fi
 
 _prepare-var-app-local-data:
@@ -315,7 +394,18 @@ _prepare-var-app-container-config_yml:
 	if [ ! -f var/app/container/config.yml ]; then
 		mkdir -p var/app/container
 		cp {{ justfile_directory() }}/etc/app/config.yml.dist var/app/container/config.yml
-		sed --in-place 's/synapse.127.0.0.1.nip.io:42020/synapse:8008/g' var/app/container/config.yml
+
+		homeserver="{{ homeserver }}"
+		if [ "$homeserver" = "continuwuity" ]; then
+			sed --in-place 's/__HOMESERVER_SERVER_NAME__/continuwuity.127.0.0.1.nip.io/g' var/app/container/config.yml
+			sed --in-place 's|__HOMESERVER_URL__|http://continuwuity.127.0.0.1.nip.io:42030|g' var/app/container/config.yml
+			sed --in-place 's/continuwuity.127.0.0.1.nip.io:42030/continuwuity:6167/g' var/app/container/config.yml
+		elif [ "$homeserver" = "synapse" ]; then
+			sed --in-place 's/__HOMESERVER_SERVER_NAME__/synapse.127.0.0.1.nip.io/g' var/app/container/config.yml
+			sed --in-place 's|__HOMESERVER_URL__|http://synapse.127.0.0.1.nip.io:42020|g' var/app/container/config.yml
+			sed --in-place 's/synapse.127.0.0.1.nip.io:42020/synapse:8008/g' var/app/container/config.yml
+		fi
+
 		sed --in-place 's/127.0.0.1:42026/ollama:11434/g' var/app/container/config.yml
 		sed --in-place 's/127.0.0.1:42027/localai:8080/g' var/app/container/config.yml
 	fi