feat(room): inject repository details into AI system prompt on mention

When a user mentions a repository in room chat, extract the repo name
from @[repo:name:label] brackets, look up the full repo model from the
database, and inject its details (name, description, default branch,
visibility) into the AI message context. Works independently of
embed_service availability.

libs/agent/chat/service.rs

@@ -605,19 +605,37 @@ impl ChatService {
             }
         }
 
-        if let Some(embed_service) = &self.embed_service {
         for mention in &request.mention {
             match mention {
                 Mention::Repo(repo) => {
+                    // Inject repo details into system prompt so AI knows the repo context
+                    let mut parts = vec![
+                        format!("Name: {}", repo.repo_name),
+                        format!("ID: {}", repo.id),
+                    ];
+                    if let Some(ref desc) = repo.description {
+                        parts.push(format!("Description: {}", desc));
+                    }
+                    parts.push(format!("Default branch: {}", repo.default_branch));
+                    parts.push(format!("Private: {}", if repo.is_private { "yes" } else { "no" }));
+                    parts.push(format!("Created: {}", repo.created_at.format("%Y-%m-%d")));
+                    messages.push(ChatRequestMessage::system(format!(
+                        "Mentioned repository:\n{}",
+                        parts.join("\n")
+                    )));
+
+                    // Vector search for related issues and repos (enhancement, optional)
+                    if let Some(embed_service) = &self.embed_service {
                         let query = format!(
                             "{} {}",
                             repo.repo_name,
                             repo.description.as_deref().unwrap_or_default()
                         );
-                        match embed_service.search_issues(&query, 5).await {
-                            Ok(issues) if !issues.is_empty() => {
+                        if let Ok(issues) = embed_service.search_issues(&query, 5).await {
+                            if !issues.is_empty() {
                                 let context = format!(
-                                    "Related issues:\n{}",
+                                    "Related issues for repo {}:\n{}",
+                                    repo.repo_name,
                                     issues
                                         .iter()
                                         .map(|i| format!("- {}", i.payload.text))
@@ -626,15 +644,11 @@ impl ChatService {
                                 );
                                 messages.push(ChatRequestMessage::system(context));
                             }
-                            Err(e) => {
-                                let _ = e;
                         }
-                            _ => {}
-                        }
-                        match embed_service.search_repos(&query, 3).await {
-                            Ok(repos) if !repos.is_empty() => {
+                        if let Ok(repos) = embed_service.search_repos(&query, 3).await {
+                            if !repos.is_empty() {
                                 let context = format!(
-                                    "Related repositories:\n{}",
+                                    "Similar repositories:\n{}",
                                     repos
                                         .iter()
                                         .map(|r| format!("- {}", r.payload.text))
@@ -643,10 +657,7 @@ impl ChatService {
                                 );
                                 messages.push(ChatRequestMessage::system(context));
                             }
-                            Err(e) => {
-                                let _ = e;
                         }
-                            _ => {}
                     }
                 }
                 Mention::User(user) => {
@@ -667,7 +678,6 @@ impl ChatService {
                 }
             }
         }
-        }
 
         let skill_contexts = self.build_skill_context(request).await;
         for ctx in skill_contexts {

libs/room/src/service/history.rs

@@ -1,9 +1,11 @@
 use db::database::AppDatabase;
+use models::repos::repo;
 use models::rooms::room_ai;
 use models::rooms::room_message::{Column as RmCol, Entity as RoomMessage};
 use sea_orm::{ColumnTrait, EntityTrait, QueryFilter, QueryOrder, QuerySelect};
 use uuid::Uuid;
 
+use super::patterns::mention_bracket_re;
 use crate::error::RoomError;
 
 pub async fn get_room_history(
@@ -57,6 +59,34 @@ pub async fn get_room_ai_config(
     Ok(ai_config)
 }
 
-pub async fn extract_mention_context(_content: &str) -> Vec<agent::chat::Mention> {
-    Vec::new()
+pub async fn extract_mention_context(
+    db: &AppDatabase,
+    project_id: Uuid,
+    content: &str,
+) -> Vec<agent::chat::Mention> {
+    let mut mentions: Vec<agent::chat::Mention> = Vec::new();
+    let mut seen_repos: Vec<String> = Vec::new();
+
+    for cap in mention_bracket_re().captures_iter(content) {
+        if let (Some(type_m), Some(id_m)) = (cap.get(1), cap.get(2)) {
+            if type_m.as_str() == "repo" {
+                let repo_name = id_m.as_str().trim().to_string();
+                if repo_name.is_empty() || seen_repos.contains(&repo_name) {
+                    continue;
+                }
+                seen_repos.push(repo_name.clone());
+
+                if let Ok(Some(repo_model)) = repo::Entity::find()
+                    .filter(repo::Column::Project.eq(project_id))
+                    .filter(repo::Column::RepoName.eq(&repo_name))
+                    .one(db)
+                    .await
+                {
+                    mentions.push(agent::chat::Mention::Repo(repo_model));
+                }
+            }
+        }
+    }
+
+    mentions
 }

libs/room/src/service/mod.rs

@@ -374,7 +374,7 @@ impl RoomService {
             .collect();
         let user_names = self.get_user_names(&user_ids).await;
 
-        let mentions = history::extract_mention_context(&content).await;
+        let mentions = history::extract_mention_context(&self.db, room.project, &content).await;
 
         let request = AiRequest {
             db: self.db.clone(),