feat: implement thought thread retrieval with replies and visibility filtering

thoughts-backend/api/src/routers/thought.rs

@@ -11,7 +11,10 @@ use app::{
     persistence::thought::{create_thought, delete_thought, get_thought},
     state::AppState,
 };
-use models::{params::thought::CreateThoughtParams, schemas::thought::ThoughtSchema};
+use models::{
+    params::thought::CreateThoughtParams,
+    schemas::thought::{ThoughtSchema, ThoughtThreadSchema},
+};
 use sea_orm::prelude::Uuid;
 
 use crate::{
@@ -118,8 +121,33 @@ async fn thoughts_delete(
     Ok(StatusCode::NO_CONTENT)
 }
 
+#[utoipa::path(
+    get,
+    path = "/{id}/thread",
+    params(
+        ("id" = Uuid, Path, description = "Thought ID")
+    ),
+    responses(
+        (status = 200, description = "Thought thread found", body = ThoughtThreadSchema),
+        (status = 404, description = "Not Found", body = ApiErrorResponse)
+    )
+)]
+async fn get_thought_thread(
+    State(state): State<AppState>,
+    Path(id): Path<Uuid>,
+    viewer: OptionalAuthUser,
+) -> Result<impl IntoResponse, ApiError> {
+    let viewer_id = viewer.0.map(|u| u.id);
+    let thread = app::persistence::thought::get_thought_with_replies(&state.conn, id, viewer_id)
+        .await?
+        .ok_or(UserError::NotFound)?;
+
+    Ok(Json(thread))
+}
+
 pub fn create_thought_router() -> Router<AppState> {
     Router::new()
         .route("/", post(thoughts_post))
+        .route("/{id}/thread", get(get_thought_thread))
         .route("/{id}", get(get_thought_by_id).delete(thoughts_delete))
 }