feat: add delete chat turn functionality with attachment cleanup

deeptutor/api/routers/sessions.py

@@ -10,6 +10,7 @@
 from pydantic import BaseModel, Field, field_validator
 
 from deeptutor.services.session import get_session_store, get_sqlite_session_store
+from deeptutor.services.storage.attachment_store import get_attachment_store
 
 logger = logging.getLogger(__name__)
 
@@ -106,9 +107,32 @@ async def delete_session(session_id: str):
     deleted = await store.delete_session(session_id)
     if not deleted:
         raise HTTPException(status_code=404, detail="Session not found")
+    try:
+        await get_attachment_store().delete_session(session_id)
+    except Exception:
+        logger.exception("failed to clean up attachments for session %s", session_id)
     return {"deleted": True, "session_id": session_id}
 
 
+@router.delete("/{session_id}/messages/{message_id}")
+async def delete_turn_by_message(session_id: str, message_id: int):
+    store = get_sqlite_session_store()
+    result = await store.delete_turn_by_message(session_id, message_id)
+    if result["was_running"]:
+        raise HTTPException(
+            status_code=409, detail="Cannot delete a message while its turn is running"
+        )
+    if not result["deleted"]:
+        raise HTTPException(status_code=404, detail="Message not found")
+    attachment_store = get_attachment_store()
+    for aid in result["attachment_ids"]:
+        try:
+            await attachment_store.delete_attachment(session_id, aid)
+        except Exception:
+            logger.exception("failed to delete attachment %s for session %s", aid, session_id)
+    return result
+
+
 @router.post("/{session_id}/quiz-results")
 async def record_quiz_results(session_id: str, payload: QuizResultsRequest):
     if not payload.answers:

deeptutor/services/session/sqlite_store.py

@@ -648,6 +648,125 @@ def _delete_message_sync(self, message_id: int | str) -> bool:
     async def delete_message(self, message_id: int | str) -> bool:
         return await self._run(self._delete_message_sync, message_id)
 
+    def _delete_turn_by_message_sync(self, session_id: str, message_id: int) -> dict[str, Any]:
+        with self._connect() as conn:
+            msg = conn.execute(
+                """
+                SELECT id, session_id, role, attachments_json, created_at
+                FROM messages
+                WHERE id = ?
+                """,
+                (int(message_id),),
+            ).fetchone()
+            if msg is None or msg["session_id"] != session_id:
+                return {
+                    "deleted": False,
+                    "attachment_ids": [],
+                    "turn_id": None,
+                    "was_running": False,
+                }
+
+            role = msg["role"]
+            paired_msg = None
+            if role == "user":
+                paired_msg = conn.execute(
+                    """
+                    SELECT id, session_id, role, attachments_json, created_at
+                    FROM messages
+                    WHERE session_id = ? AND role = 'assistant' AND id > ?
+                    ORDER BY id ASC
+                    LIMIT 1
+                    """,
+                    (session_id, int(message_id)),
+                ).fetchone()
+            elif role == "assistant":
+                paired_msg = conn.execute(
+                    """
+                    SELECT id, session_id, role, attachments_json, created_at
+                    FROM messages
+                    WHERE session_id = ? AND role = 'user' AND id < ?
+                    ORDER BY id DESC
+                    LIMIT 1
+                    """,
+                    (session_id, int(message_id)),
+                ).fetchone()
+
+            user_msg = msg if role == "user" else paired_msg
+            turn_id = None
+            was_running = False
+            if user_msg is not None:
+                user_created_at = user_msg["created_at"]
+                turn_row = conn.execute(
+                    """
+                    SELECT id, status
+                    FROM turns
+                    WHERE session_id = ? AND created_at >= ?
+                    ORDER BY created_at ASC
+                    LIMIT 1
+                    """,
+                    (session_id, user_created_at),
+                ).fetchone()
+                if turn_row is not None:
+                    turn_id = turn_row["id"]
+                    was_running = turn_row["status"] == "running"
+
+            if was_running:
+                return {
+                    "deleted": False,
+                    "attachment_ids": [],
+                    "turn_id": turn_id,
+                    "was_running": True,
+                }
+
+            attachment_ids: list[str] = []
+            for m in [msg, paired_msg]:
+                if m is not None:
+                    atts = _json_loads(m["attachments_json"], [])
+                    for att in atts:
+                        aid = att.get("id") or att.get("attachment_id")
+                        if aid:
+                            attachment_ids.append(aid)
+
+            if turn_id is not None:
+                conn.execute("DELETE FROM turn_events WHERE turn_id = ?", (turn_id,))
+                conn.execute("DELETE FROM turns WHERE id = ?", (turn_id,))
+
+            ids_to_delete = [int(message_id)]
+            if paired_msg is not None:
+                ids_to_delete.append(int(paired_msg["id"]))
+            conn.execute(
+                f"DELETE FROM messages WHERE id IN ({','.join('?' * len(ids_to_delete))})",  # nosec B608
+                tuple(ids_to_delete),
+            )
+
+            session_row = conn.execute(
+                "SELECT summary_up_to_msg_id FROM sessions WHERE id = ?",
+                (session_id,),
+            ).fetchone()
+            if session_row is not None:
+                summary_up_to = int(session_row["summary_up_to_msg_id"])
+                if any(mid <= summary_up_to for mid in ids_to_delete):
+                    conn.execute(
+                        "UPDATE sessions SET summary_up_to_msg_id = 0 WHERE id = ?",
+                        (session_id,),
+                    )
+
+            conn.execute(
+                "UPDATE sessions SET updated_at = ? WHERE id = ?",
+                (time.time(), session_id),
+            )
+            conn.commit()
+
+        return {
+            "deleted": True,
+            "attachment_ids": attachment_ids,
+            "turn_id": turn_id,
+            "was_running": was_running,
+        }
+
+    async def delete_turn_by_message(self, session_id: str, message_id: int) -> dict[str, Any]:
+        return await self._run(self._delete_turn_by_message_sync, session_id, message_id)
+
     def _get_last_message_sync(
         self, session_id: str, role: str | None = None
     ) -> dict[str, Any] | None:

deeptutor/services/storage/attachment_store.py

@@ -88,6 +88,9 @@ async def put(
     async def delete_session(self, session_id: str) -> None:
         """Best-effort cleanup of all attachments for *session_id*."""
 
+    async def delete_attachment(self, session_id: str, attachment_id: str) -> None:
+        """Best-effort cleanup of a single attachment identified by *attachment_id*."""
+
     def resolve_path(self, *, session_id: str, attachment_id: str, filename: str) -> Path | None:
         """Return the absolute path on disk for an attachment, or ``None``
         if it does not exist or escapes the storage root.
@@ -186,6 +189,13 @@ async def delete_session(self, session_id: str) -> None:
         loop = asyncio.get_running_loop()
         await loop.run_in_executor(None, self._rmtree_sync, session_dir)
 
+    async def delete_attachment(self, session_id: str, attachment_id: str) -> None:
+        session_dir = self._session_dir(session_id)
+        if not session_dir.exists():
+            return
+        loop = asyncio.get_running_loop()
+        await loop.run_in_executor(None, self._delete_attachment_sync, session_dir, attachment_id)
+
     @staticmethod
     def _rmtree_sync(path: Path) -> None:
         import shutil
@@ -195,6 +205,21 @@ def _rmtree_sync(path: Path) -> None:
         except OSError as exc:
             logger.warning("failed to clean up attachment dir %s: %s", path, exc)
 
+    @staticmethod
+    def _delete_attachment_sync(session_dir: Path, attachment_id: str) -> None:
+        prefix = f"{attachment_id}_"
+        for entry in session_dir.iterdir():
+            if entry.name.startswith(prefix):
+                try:
+                    entry.unlink()
+                except OSError as exc:
+                    logger.warning("failed to delete attachment file %s: %s", entry, exc)
+        try:
+            if session_dir.exists() and not any(session_dir.iterdir()):
+                session_dir.rmdir()
+        except OSError as exc:
+            logger.warning("failed to remove empty attachment dir %s: %s", session_dir, exc)
+
     def resolve_path(self, *, session_id: str, attachment_id: str, filename: str) -> Path | None:
         stored = self._stored_filename(attachment_id, filename)
         target = self._safe_join(session_id, stored)

web/app/(workspace)/chat/[[...sessionId]]/page.tsx

@@ -310,6 +310,7 @@ export default function ChatPage() {
     sendMessage,
     cancelStreamingTurn,
     regenerateLastMessage,
+    deleteTurn,
     newSession,
     loadSession,
   } = useUnifiedChat();
@@ -1645,6 +1646,7 @@ export default function ChatPage() {
               onRegenerateMessage={handleRegenerateMessage}
               onConfirmOutline={handleConfirmOutline}
               onPreviewAttachment={handlePreviewMessageAttachment}
+              onDeleteTurn={deleteTurn}
             />
             <div ref={messagesEndRef} className="h-px w-full shrink-0" />
           </div>

web/components/chat/home/ChatMessages.tsx

@@ -12,6 +12,7 @@ import {
   RefreshCcw,
   Wand2,
   X,
+  Trash2,
   Zap,
   type LucideIcon,
 } from "lucide-react";
@@ -52,6 +53,7 @@ const VisualizationViewer = dynamic(
 );
 
 interface ChatMessageItem {
+  id?: number;
   role: "user" | "assistant" | "system";
   content: string;
   capability?: string;
@@ -336,17 +338,57 @@ const UserMessage = memo(function UserMessage({
   msg,
   index,
   onPreviewAttachment,
+  onDeleteTurn,
 }: {
   msg: ChatMessageItem;
   index: number;
   onPreviewAttachment?: (attachment: MessageAttachment) => void;
+  onDeleteTurn?: (messageId: number) => void;
 }) {
   const { t } = useTranslation();
+  const [confirmDelete, setConfirmDelete] = useState(false);
   if (msg.content.startsWith("[Quiz Performance]")) return null;
 
   return (
-    <div key={`${msg.role}-${index}`} className="flex justify-end">
+    <div key={`${msg.role}-${index}`} className="group flex justify-end">
       <div className="max-w-[75%] space-y-1.5">
+        <div className="flex justify-end">
+          <div className="relative">
+            {!confirmDelete ? (
+              <button
+                type="button"
+                onClick={() => setConfirmDelete(true)}
+                className="rounded-md p-1 text-[var(--muted-foreground)] opacity-0 transition-opacity group-hover:opacity-100 hover:text-[var(--destructive)]"
+                title={t("Delete")}
+              >
+                <Trash2 size={14} strokeWidth={1.5} />
+              </button>
+            ) : (
+              <div className="flex items-center gap-1.5 text-[12px]">
+                <span className="text-[var(--muted-foreground)]">
+                  {t("Delete this turn?")}
+                </span>
+                <button
+                  type="button"
+                  onClick={() => {
+                    if (msg.id != null) onDeleteTurn?.(msg.id);
+                    setConfirmDelete(false);
+                  }}
+                  className="rounded-md px-2 py-0.5 font-medium text-[var(--destructive)] hover:bg-[var(--destructive)]/10"
+                >
+                  {t("Delete")}
+                </button>
+                <button
+                  type="button"
+                  onClick={() => setConfirmDelete(false)}
+                  className="rounded-md px-2 py-0.5 font-medium text-[var(--muted-foreground)] hover:bg-[var(--muted)]/40"
+                >
+                  {t("Cancel")}
+                </button>
+              </div>
+            )}
+          </div>
+        </div>
         <div className="flex justify-end pr-1">
           <span className="text-[10px] tracking-wide text-[var(--muted-foreground)]">
             {t(getModeBadgeLabel(msg.capability))}
@@ -686,6 +728,7 @@ export const ChatMessageList = memo(function ChatMessageList({
   onConfirmOutline,
   onPreviewAttachment,
   onSwitchToManualMode,
+  onDeleteTurn,
 }: {
   messages: ChatMessageItem[];
   isStreaming: boolean;
@@ -707,6 +750,7 @@ export const ChatMessageList = memo(function ChatMessageList({
   // button after a terminal failure. Optional so non-auto chat surfaces don't
   // have to wire it.
   onSwitchToManualMode?: () => void;
+  onDeleteTurn?: (messageId: number) => void;
 }) {
   const { t } = useTranslation();
   const outlineStatusByIndex = useMemo(() => {
@@ -783,6 +827,7 @@ export const ChatMessageList = memo(function ChatMessageList({
               msg={msg}
               index={i}
               onPreviewAttachment={onPreviewAttachment}
+              onDeleteTurn={onDeleteTurn}
             />
           );
         }