From 20e0ccf783ec0668636cc2b1cb5336e891e741ca Mon Sep 17 00:00:00 2001
From: Peisong Xiao <peisong.xiao.xps@gmail.com>
Date: Tue, 14 Oct 2025 02:25:47 -0400
Subject: [PATCH] cleaned files

---
 backend/backend.go | 114 ---------------------------------------------
 1 file changed, 114 deletions(-)
 delete mode 100644 backend/backend.go

diff --git a/backend/backend.go b/backend/backend.go
deleted file mode 100644
index fb77382..0000000
--- a/backend/backend.go
+++ /dev/null
@@ -1,114 +0,0 @@
-package db
-
-import (
-	"fmt"
-	"context"
-	"database/sql"
-)
-
-type Repo struct{ DB *sql.DB }
-
-func NewRepo(db *sql.DB) *Repo { return &Repo{DB: db} }
-
-// --- Conversations ---
-const qCreateConversation = `
-INSERT INTO conversations (owner_id, title) VALUES (?, ?);
-`
-func (r *Repo) CreateConversation(ctx context.Context, ownerID int64, title string) (int64, error) {
-	res, err := r.DB.ExecContext(ctx, qCreateConversation, ownerID, title)
-	if err != nil { return 0, err }
-	return res.LastInsertId()
-}
-
-const qListConversations = `
-SELECT id, owner_id, title, created_at
-FROM conversations
-WHERE owner_id = ?
-ORDER BY created_at DESC, id DESC;
-`
-func (r *Repo) ListConversations(ctx context.Context, ownerID int64) (*sql.Rows, error) {
-	return r.DB.QueryContext(ctx, qListConversations, ownerID)
-}
-
-// --- Nodes (commits) ---
-const qCreateNode = `
-INSERT INTO nodes (conversation_id, author_kind, content) VALUES (?, ?, ?);
-`
-func (r *Repo) CreateNode(ctx context.Context, convID int64, authorKind, content string) (int64, error) {
-	res, err := r.DB.ExecContext(ctx, qCreateNode, convID, authorKind, content)
-	if err != nil { return 0, err }
-	return res.LastInsertId()
-}
-
-// --- Branches ---
-const qCreateBranch = `
-INSERT INTO branches (conversation_id, name, head_node_id) VALUES (?, ?, ?)
-ON DUPLICATE KEY UPDATE head_node_id = VALUES(head_node_id);
-`
-func (r *Repo) CreateOrUpdateBranch(ctx context.Context, convID int64, name string, headNodeID int64) (int64, error) {
-	res, err := r.DB.ExecContext(ctx, qCreateBranch, convID, name, headNodeID)
-	if err != nil { return 0, err }
-	return res.LastInsertId()
-}
-
-const qGetBranch = `
-SELECT id, conversation_id, name, head_node_id, created_at
-FROM branches
-WHERE conversation_id = ? AND name = ?
-LIMIT 1;
-`
-func (r *Repo) GetBranch(ctx context.Context, convID int64, name string) *sql.Row {
-	return r.DB.QueryRowContext(ctx, qGetBranch, convID, name)
-}
-
-const qMoveBranchHead = `
-UPDATE branches SET head_node_id = ? WHERE id = ?;
-`
-func (r *Repo) MoveBranchHead(ctx context.Context, branchID, newHead int64) error {
-	_, err := r.DB.ExecContext(ctx, qMoveBranchHead, newHead, branchID)
-	return err
-}
-
-// --- Edges (DAG) ---
-const qCycleGuard = `
-WITH RECURSIVE downchain AS (
-  SELECT e.child_id
-  FROM edges e
-  WHERE e.parent_id = ?
-  UNION ALL
-  SELECT e.child_id
-  FROM edges e
-  JOIN downchain d ON d.child_id = e.parent_id
-)
-SELECT 1 FROM downchain WHERE child_id = ? LIMIT 1;
-`
-
-const qInsertEdge = `INSERT IGNORE INTO edges (parent_id, child_id) VALUES (?, ?);`
-
-func (r *Repo) LinkEdgeCycleSafe(ctx context.Context, tx *sql.Tx, parentID, childID int64) error {
-	// cycle check: is parent reachable from child already?
-	var one int
-	err := tx.QueryRowContext(ctx, qCycleGuard, childID, parentID).Scan(&one)
-	if err != nil && err != sql.ErrNoRows {
-		return err
-	}
-	if err == nil {
-		// found a row -> would create a cycle
-		return fmt.Errorf("cycle detected: %d -> %d", parentID, childID)
-	}
-	_, err = tx.ExecContext(ctx, qInsertEdge, parentID, childID)
-	return err
-}
-
-// --- Ancestor step (latest parent) ---
-const qLatestParent = `
-SELECT p.id, p.conversation_id, p.author_kind, p.content, p.created_at
-FROM edges e
-JOIN nodes p ON p.id = e.parent_id
-WHERE e.child_id = ?
-ORDER BY p.created_at DESC, p.id DESC
-LIMIT 1;
-`
-func (r *Repo) LatestParent(ctx context.Context, childID int64) *sql.Row {
-	return r.DB.QueryRowContext(ctx, qLatestParent, childID)
-}