Add sender context mode for text generation (#104)

Add a per-room/global `sender_context_mode` setting that optionally
prefixes conversation messages with sender metadata before sending them
to the model provider.

This helps models distinguish between participants in multi-user rooms.
                                                                                                                                                                                                                                                             
Three modes are supported:
- `disabled` (default, no change)
- `matrix_user_id` (prefixes with `[sender=@user:server]`)
- `matrix_user_id_and_timestamp` (adds `send_at`; Example: `[sender=@user:server sent_at=<ISO 8601>]`)
                                                                                                                                                                                                                                                             
Sender context is applied to user and assistant text messages only,
skipping system prompts and non-text content.

Mixed-sender merged turns (something we intentionally do for Anthropic)
have their `sender_id` cleared to avoid misattribution.

src/entity/room_config_context.rs

@@ -5,8 +5,9 @@ use super::roomconfig::RoomConfig;
 
 use crate::entity::roomconfig::{
     SpeechToTextFlowType, SpeechToTextMessageTypeForNonThreadedOnlyTranscribedMessages,
-    TextGenerationAutoUsage, TextGenerationPrefixRequirementType, TextToSpeechBotMessagesFlowType,
-    TextToSpeechUserMessagesFlowType, defaults as roomconfig_defaults,
+    TextGenerationAutoUsage, TextGenerationPrefixRequirementType, TextGenerationSenderContextMode,
+    TextToSpeechBotMessagesFlowType, TextToSpeechUserMessagesFlowType,
+    defaults as roomconfig_defaults,
 };
 
 #[derive(Debug)]
@@ -135,6 +136,20 @@ impl RoomConfigContext {
             .unwrap_or(false)
     }
 
+    pub fn text_generation_sender_context_mode(&self) -> TextGenerationSenderContextMode {
+        self.room_config
+            .settings
+            .text_generation
+            .sender_context_mode
+            .or({
+                self.global_config
+                    .fallback_room_settings
+                    .text_generation
+                    .sender_context_mode
+            })
+            .unwrap_or(roomconfig_defaults::TEXT_GENERATION_SENDER_CONTEXT_MODE)
+    }
+
     pub fn text_generation_prefix_requirement_type(&self) -> TextGenerationPrefixRequirementType {
         self.room_config
             .settings

src/entity/roomconfig/defaults.rs

@@ -1,5 +1,7 @@
 use super::{SpeechToTextFlowType, SpeechToTextMessageTypeForNonThreadedOnlyTranscribedMessages};
-use super::{TextGenerationAutoUsage, TextGenerationPrefixRequirementType};
+use super::{
+    TextGenerationAutoUsage, TextGenerationPrefixRequirementType, TextGenerationSenderContextMode,
+};
 use super::{TextToSpeechBotMessagesFlowType, TextToSpeechUserMessagesFlowType};
 
 pub const TEXT_GENERATION_PREFIX_REQUIREMENT_TYPE: TextGenerationPrefixRequirementType =
@@ -7,6 +9,9 @@ pub const TEXT_GENERATION_PREFIX_REQUIREMENT_TYPE: TextGenerationPrefixRequireme
 
 pub const TEXT_GENERATION_AUTO_USAGE: TextGenerationAutoUsage = TextGenerationAutoUsage::Always;
 
+pub const TEXT_GENERATION_SENDER_CONTEXT_MODE: TextGenerationSenderContextMode =
+    TextGenerationSenderContextMode::Disabled;
+
 pub const TEXT_TO_SPEECH_BOT_MESSAGES_FLOW_TYPE: TextToSpeechBotMessagesFlowType =
     TextToSpeechBotMessagesFlowType::OnDemandForVoice;
 

src/entity/roomconfig/entity/mod.rs

@@ -16,7 +16,9 @@ pub use handler::RoomSettingsHandler;
 pub use speech_to_text::{
     SpeechToTextFlowType, SpeechToTextMessageTypeForNonThreadedOnlyTranscribedMessages,
 };
-pub use text_generation::{TextGenerationAutoUsage, TextGenerationPrefixRequirementType};
+pub use text_generation::{
+    TextGenerationAutoUsage, TextGenerationPrefixRequirementType, TextGenerationSenderContextMode,
+};
 pub use text_to_speech::{TextToSpeechBotMessagesFlowType, TextToSpeechUserMessagesFlowType};
 
 #[derive(Clone, Debug, Deserialize, Serialize, EventContent)]

src/entity/roomconfig/entity/text_generation.rs

@@ -14,6 +14,9 @@ pub struct RoomSettingsTextGeneration {
     /// When enabled, the bot will automatically tokenize messages and try to shorten the message context intelligently.
     pub context_management_enabled: Option<bool>,
 
+    /// Controls how each message in the conversation context is annotated with sender metadata.
+    pub sender_context_mode: Option<TextGenerationSenderContextMode>,
+
     /// Allows customizing the system prompt that the agent would use
     pub prompt_override: Option<String>,
 
@@ -111,3 +114,46 @@ impl std::fmt::Display for TextGenerationAutoUsage {
         }
     }
 }
+
+#[derive(Clone, Copy, Debug, Deserialize, Serialize, PartialEq)]
+pub enum TextGenerationSenderContextMode {
+    #[serde(rename = "disabled")]
+    Disabled,
+
+    #[serde(rename = "matrix_user_id")]
+    MatrixUserId,
+
+    #[serde(rename = "matrix_user_id_and_timestamp")]
+    MatrixUserIdAndTimestamp,
+}
+
+impl TextGenerationSenderContextMode {
+    pub fn choices() -> Vec<Self> {
+        vec![
+            Self::Disabled,
+            Self::MatrixUserId,
+            Self::MatrixUserIdAndTimestamp,
+        ]
+    }
+
+    pub fn from_str(s: &str) -> Option<Self> {
+        match s {
+            "disabled" => Some(Self::Disabled),
+            "matrix_user_id" => Some(Self::MatrixUserId),
+            "matrix_user_id_and_timestamp" => Some(Self::MatrixUserIdAndTimestamp),
+            _ => None,
+        }
+    }
+}
+
+impl std::fmt::Display for TextGenerationSenderContextMode {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            TextGenerationSenderContextMode::Disabled => write!(f, "disabled"),
+            TextGenerationSenderContextMode::MatrixUserId => write!(f, "matrix_user_id"),
+            TextGenerationSenderContextMode::MatrixUserIdAndTimestamp => {
+                write!(f, "matrix_user_id_and_timestamp")
+            }
+        }
+    }
+}

src/entity/roomconfig/mod.rs

@@ -6,8 +6,8 @@ use mxlink::helpers::account_data_config::RoomConfigManager as AccountDataRoomCo
 pub use entity::{RoomConfig, RoomConfigCarrierContent, RoomSettings, RoomSettingsHandler};
 pub use entity::{
     SpeechToTextFlowType, SpeechToTextMessageTypeForNonThreadedOnlyTranscribedMessages,
-    TextGenerationAutoUsage, TextGenerationPrefixRequirementType, TextToSpeechBotMessagesFlowType,
-    TextToSpeechUserMessagesFlowType,
+    TextGenerationAutoUsage, TextGenerationPrefixRequirementType, TextGenerationSenderContextMode,
+    TextToSpeechBotMessagesFlowType, TextToSpeechUserMessagesFlowType,
 };
 
 pub type RoomConfigurationManager =