diff --git a/server/src/chat/transport/matrix/bot.rs b/server/src/chat/transport/matrix/bot.rs
index d424b57..6bbeaca 100644
--- a/server/src/chat/transport/matrix/bot.rs
+++ b/server/src/chat/transport/matrix/bot.rs
@@ -217,7 +217,7 @@ pub async fn run_bot(
 ) -> Result<(), String> {
     let store_path = project_root.join(".storkit").join("matrix_store");
     let client = Client::builder()
-        .homeserver_url(&config.homeserver)
+        .homeserver_url(config.homeserver.as_deref().unwrap_or_default())
         .sqlite_store(&store_path, None)
         .build()
         .await
@@ -232,7 +232,10 @@ pub async fn run_bot(
 
     let mut login_builder = client
         .matrix_auth()
-        .login_username(&config.username, &config.password)
+        .login_username(
+            config.username.as_deref().unwrap_or_default(),
+            config.password.as_deref().unwrap_or_default(),
+        )
         .initial_device_display_name("Storkit Bot");
 
     if let Some(ref device_id) = saved_device_id {
@@ -265,8 +268,10 @@ pub async fn run_bot(
     {
         use matrix_sdk::ruma::api::client::uiaa;
         let password_auth = uiaa::AuthData::Password(uiaa::Password::new(
-            uiaa::UserIdentifier::UserIdOrLocalpart(config.username.clone()),
-            config.password.clone(),
+            uiaa::UserIdentifier::UserIdOrLocalpart(
+                config.username.clone().unwrap_or_default(),
+            ),
+            config.password.clone().unwrap_or_default(),
         ));
         if let Err(e) = client
             .encryption()
diff --git a/server/src/chat/transport/matrix/config.rs b/server/src/chat/transport/matrix/config.rs
index cbfc9eb..0575c98 100644
--- a/server/src/chat/transport/matrix/config.rs
+++ b/server/src/chat/transport/matrix/config.rs
@@ -13,11 +13,17 @@ fn default_permission_timeout_secs() -> u64 {
 #[derive(Deserialize, Clone, Debug)]
 pub struct BotConfig {
     /// Matrix homeserver URL, e.g. `https://matrix.example.com`
-    pub homeserver: String,
+    /// Only required when `transport = "matrix"` (the default).
+    #[serde(default)]
+    pub homeserver: Option<String>,
     /// Bot user ID, e.g. `@storykit:example.com`
-    pub username: String,
+    /// Only required when `transport = "matrix"`.
+    #[serde(default)]
+    pub username: Option<String>,
     /// Bot password
-    pub password: String,
+    /// Only required when `transport = "matrix"`.
+    #[serde(default)]
+    pub password: Option<String>,
     /// Matrix room IDs to join, e.g. `["!roomid:example.com"]`.
     /// Use an array for multiple rooms; a single string is accepted via the
     /// deprecated `room_id` key for backwards compatibility.
@@ -227,12 +233,33 @@ impl BotConfig {
                 );
                 return None;
             }
-        } else if config.room_ids.is_empty() {
-            eprintln!(
-                "[matrix-bot] bot.toml has no room_ids configured — \
-                 add `room_ids = [\"!roomid:example.com\"]` to bot.toml"
-            );
-            return None;
+        } else {
+            // Default transport is Matrix — validate Matrix-specific fields.
+            if config.homeserver.as_ref().is_none_or(|s| s.is_empty()) {
+                eprintln!(
+                    "[bot] bot.toml: transport=\"matrix\" requires homeserver"
+                );
+                return None;
+            }
+            if config.username.as_ref().is_none_or(|s| s.is_empty()) {
+                eprintln!(
+                    "[bot] bot.toml: transport=\"matrix\" requires username"
+                );
+                return None;
+            }
+            if config.password.as_ref().is_none_or(|s| s.is_empty()) {
+                eprintln!(
+                    "[bot] bot.toml: transport=\"matrix\" requires password"
+                );
+                return None;
+            }
+            if config.room_ids.is_empty() {
+                eprintln!(
+                    "[matrix-bot] bot.toml has no room_ids configured — \
+                     add `room_ids = [\"!roomid:example.com\"]` to bot.toml"
+                );
+                return None;
+            }
         }
         Some(config)
     }
@@ -335,8 +362,8 @@ enabled = true
         let result = BotConfig::load(tmp.path());
         assert!(result.is_some());
         let config = result.unwrap();
-        assert_eq!(config.homeserver, "https://matrix.example.com");
-        assert_eq!(config.username, "@bot:example.com");
+        assert_eq!(config.homeserver.as_deref(), Some("https://matrix.example.com"));
+        assert_eq!(config.username.as_deref(), Some("@bot:example.com"));
         assert_eq!(
             config.effective_room_ids(),
             &["!abc:example.com", "!def:example.com"]
diff --git a/server/src/chat/transport/matrix/mod.rs b/server/src/chat/transport/matrix/mod.rs
index d0da21e..1f20a84 100644
--- a/server/src/chat/transport/matrix/mod.rs
+++ b/server/src/chat/transport/matrix/mod.rs
@@ -84,7 +84,7 @@ pub fn spawn_bot(
 
     crate::slog!(
         "[matrix-bot] Starting Matrix bot → homeserver={} rooms={:?}",
-        config.homeserver,
+        config.homeserver.as_deref().unwrap_or("(none)"),
         config.effective_room_ids()
     );