From 96f6b540fea9f6a2857126b7b1e02ed68b7dfac1 Mon Sep 17 00:00:00 2001
From: Abhimanyu Saharan <asaharan@onemindservices.com>
Date: Mon, 2 Feb 2026 13:47:36 +0530
Subject: [PATCH] feat(comments): add reply threading + UI

---
 ...9d3d9b9c1a23_add_reply_to_task_comments.py | 32 +++++++++++++++
 backend/app/api/work.py                       |  6 +++
 backend/app/models/work.py                    |  4 ++
 backend/app/schemas/work.py                   |  1 +
 frontend/src/app/projects/[id]/page.tsx       | 41 +++++++++++++++++--
 5 files changed, 80 insertions(+), 4 deletions(-)
 create mode 100644 backend/alembic/versions/9d3d9b9c1a23_add_reply_to_task_comments.py

diff --git a/backend/alembic/versions/9d3d9b9c1a23_add_reply_to_task_comments.py b/backend/alembic/versions/9d3d9b9c1a23_add_reply_to_task_comments.py
new file mode 100644
index 00000000..f673b954
--- /dev/null
+++ b/backend/alembic/versions/9d3d9b9c1a23_add_reply_to_task_comments.py
@@ -0,0 +1,32 @@
+"""add reply_to_comment_id to task_comments
+
+Revision ID: 9d3d9b9c1a23
+Revises: 157587037601
+Create Date: 2026-02-02 08:15:00.000000
+
+"""
+
+from alembic import op
+import sqlalchemy as sa
+
+# revision identifiers, used by Alembic.
+revision = "9d3d9b9c1a23"
+down_revision = "157587037601"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.add_column("task_comments", sa.Column("reply_to_comment_id", sa.Integer(), nullable=True))
+    op.create_foreign_key(
+        "fk_task_comments_reply_to_comment_id",
+        "task_comments",
+        "task_comments",
+        ["reply_to_comment_id"],
+        ["id"],
+    )
+
+
+def downgrade() -> None:
+    op.drop_constraint("fk_task_comments_reply_to_comment_id", "task_comments", type_="foreignkey")
+    op.drop_column("task_comments", "reply_to_comment_id")
diff --git a/backend/app/api/work.py b/backend/app/api/work.py
index b80fe007..302ab56d 100644
--- a/backend/app/api/work.py
+++ b/backend/app/api/work.py
@@ -89,6 +89,12 @@ def create_task_comment(payload: TaskCommentCreate, session: Session = Depends(g
     if payload.author_employee_id is None:
         payload = TaskCommentCreate(**{**payload.model_dump(), "author_employee_id": actor_employee_id})
     c = TaskComment(**payload.model_dump())
+
+    # Validate reply target (must exist + belong to same task)
+    if c.reply_to_comment_id is not None:
+        parent = session.get(TaskComment, c.reply_to_comment_id)
+        if parent is None or parent.task_id != c.task_id:
+            raise HTTPException(status_code=400, detail="Invalid reply_to_comment_id")
     session.add(c)
     session.commit()
     session.refresh(c)
diff --git a/backend/app/models/work.py b/backend/app/models/work.py
index 545d5657..ce7f8314 100644
--- a/backend/app/models/work.py
+++ b/backend/app/models/work.py
@@ -30,5 +30,9 @@ class TaskComment(SQLModel, table=True):
     id: int | None = Field(default=None, primary_key=True)
     task_id: int = Field(foreign_key="tasks.id", index=True)
     author_employee_id: int | None = Field(default=None, foreign_key="employees.id")
+
+    # Optional reply threading
+    reply_to_comment_id: int | None = Field(default=None, foreign_key="task_comments.id")
+
     body: str
     created_at: datetime = Field(default_factory=datetime.utcnow)
diff --git a/backend/app/schemas/work.py b/backend/app/schemas/work.py
index b483e5b6..9d067d75 100644
--- a/backend/app/schemas/work.py
+++ b/backend/app/schemas/work.py
@@ -24,4 +24,5 @@ class TaskUpdate(SQLModel):
 class TaskCommentCreate(SQLModel):
     task_id: int
     author_employee_id: int | None = None
+    reply_to_comment_id: int | None = None
     body: str
diff --git a/frontend/src/app/projects/[id]/page.tsx b/frontend/src/app/projects/[id]/page.tsx
index 3c733852..8ff0fe97 100644
--- a/frontend/src/app/projects/[id]/page.tsx
+++ b/frontend/src/app/projects/[id]/page.tsx
@@ -82,6 +82,7 @@ export default function ProjectDetailPage() {
   const [reviewerId, setReviewerId] = useState<string>("");
 
   const [commentTaskId, setCommentTaskId] = useState<number | null>(null);
+  const [replyToCommentId, setReplyToCommentId] = useState<number | null>(null);
   const [commentBody, setCommentBody] = useState("");
 
   const comments = useListTaskCommentsTaskCommentsGet(
@@ -94,6 +95,7 @@ export default function ProjectDetailPage() {
       onSuccess: () => {
         comments.refetch();
         setCommentBody("");
+        setReplyToCommentId(null);
       },
     },
   });
@@ -113,6 +115,11 @@ export default function ProjectDetailPage() {
 
   const projectMembers = memberList;
 
+  const commentById = new Map<number, (typeof commentList)[number]>();
+  for (const c of commentList) {
+    if (c.id != null) commentById.set(Number(c.id), c);
+  }
+
   return (
     <main className="mx-auto max-w-6xl p-6">
       {!Number.isFinite(projectId) ? (
@@ -258,7 +265,7 @@ export default function ProjectDetailPage() {
                       ))}
                     </div>
                     <div className="mt-2 flex gap-2">
-                      <Button variant="outline" size="sm" onClick={() => setCommentTaskId(Number(t.id))}>
+                      <Button variant="outline" size="sm" onClick={() => { setCommentTaskId(Number(t.id)); setReplyToCommentId(null); }}>
                         Comments
                       </Button>
                       <Button variant="destructive" size="sm" onClick={() => deleteTask.mutate({ taskId: Number(t.id) })}>
@@ -284,6 +291,19 @@ export default function ProjectDetailPage() {
           </CardHeader>
           <CardContent className="space-y-3">
             {addComment.error ? <div className="text-sm text-destructive">{(addComment.error as Error).message}</div> : null}
+            {replyToCommentId ? (
+              <div className="rounded-md border bg-muted/40 p-2 text-sm">
+                <div className="flex items-center justify-between gap-2">
+                  <div className="text-xs text-muted-foreground">Replying to comment #{replyToCommentId}</div>
+                  <Button variant="outline" size="sm" onClick={() => setReplyToCommentId(null)}>
+                    Cancel reply
+                  </Button>
+                </div>
+                <div className="mt-1 text-xs text-muted-foreground line-clamp-2">
+                  {commentById.get(replyToCommentId)?.body ?? "—"}
+                </div>
+              </div>
+            ) : null}
             <Textarea
               placeholder="Write a comment"
               value={commentBody}
@@ -297,6 +317,7 @@ export default function ProjectDetailPage() {
                     task_id: Number(commentTaskId),
                     author_employee_id: getActorEmployeeId(),
                     body: commentBody,
+                    reply_to_comment_id: replyToCommentId,
                   },
                 })
               }
@@ -307,9 +328,21 @@ export default function ProjectDetailPage() {
             <ul className="space-y-2">
               {commentList.map((c) => (
                 <li key={String(c.id)} className="rounded-md border p-2 text-sm">
-                  <div className="font-medium">{employeeName(c.author_employee_id)}</div>
-                  <div className="text-xs text-muted-foreground">{(c.created_at ? new Date(c.created_at).toLocaleString() : "—")}</div>
-                  <div className="mt-1">{c.body}</div>
+                  <div className="flex items-start justify-between gap-2">
+                    <div>
+                      <div className="font-medium">{employeeName(c.author_employee_id)}</div>
+                      <div className="text-xs text-muted-foreground">{(c.created_at ? new Date(c.created_at).toLocaleString() : "—")}</div>
+                    </div>
+                    <Button variant="outline" size="sm" onClick={() => setReplyToCommentId(Number(c.id))}>
+                      Reply
+                    </Button>
+                  </div>
+                  {(c.reply_to_comment_id ? (
+                    <div className="mt-2 rounded-md border bg-muted/40 p-2 text-xs">
+                      <div className="text-muted-foreground">Replying to #{c.reply_to_comment_id}: {commentById.get(Number(c.reply_to_comment_id))?.body ?? "—"}</div>
+                    </div>
+                  ) : null)}
+                  <div className="mt-2">{c.body}</div>
                 </li>
               ))}
               {commentList.length === 0 ? (