diff --git a/src-tauri/src/mcp_inject.rs b/src-tauri/src/mcp_inject.rs
index 3c145ea..790d7ce 100644
--- a/src-tauri/src/mcp_inject.rs
+++ b/src-tauri/src/mcp_inject.rs
@@ -28,7 +28,14 @@ fn validate_registered_path(raw: &str, field: &str) -> Result<PathBuf, String> {
 /// 解析项目根目录路径（WSL 项目自动转为 Windows UNC 路径）
 fn project_root(project_id: &str) -> Result<PathBuf, String> {
     let conn = db::pool().get().map_err(|e| e.to_string())?;
+    project_root_with_conn(&conn, project_id)
+}
 
+/// project_root 的依赖注入版：连接由调用方传入（业务层复用 + in-memory 测试）
+pub(crate) fn project_root_with_conn(
+    conn: &rusqlite::Connection,
+    project_id: &str,
+) -> Result<PathBuf, String> {
     let row: rusqlite::Result<(Option<String>, Option<String>, Option<String>)> = conn.query_row(
         "SELECT win_path, wsl_path, platform FROM project_workspaces WHERE id = ?1",
         [project_id],
diff --git a/src-tauri/src/mcp_tools.rs b/src-tauri/src/mcp_tools.rs
index 7451e83..6e7bce5 100644
--- a/src-tauri/src/mcp_tools.rs
+++ b/src-tauri/src/mcp_tools.rs
@@ -80,6 +80,11 @@ pub fn tools_list_result() -> Value {
                     "required": ["project_id", "content"]
                 }
             },
+            {
+                "name": "backfill_notes_archive",
+                "description": "将 project_notes 全量重建到各项目 .blueprint/notes-archive.jsonl 分片档案（可拆除性修复：笔记是全系统唯一不在 git 的原创资产）。幂等，DB 为事实源整文件重写；append_project_note 双写失败后的自愈入口。无参数。",
+                "inputSchema": { "type": "object", "properties": {}, "required": [] }
+            },
             {
                 "name": "get_blueprint_status",
                 "description": "检测项目蓝图治理状态：CONVENTIONS 规则版本是否最新、蓝图内容是否可能落后于代码（synced/rules_outdated/content_stale/none）。等价于炼境 UI 项目卡片上的蓝图状态徽章。",
@@ -386,6 +391,10 @@ pub async fn tools_call(params: Option<&Value>) -> Value {
             let content = args.get("content").and_then(|v| v.as_str()).unwrap_or("");
             append_project_note(pid, content)
         }
+        "backfill_notes_archive" => {
+            let conn = db::pool().get().map_err(|e| e.to_string())?;
+            backfill_notes_archive(&conn)
+        }
         "get_project_snapshots" => {
             let pid = args.get("project_id").and_then(|v| v.as_str()).unwrap_or("");
             let days = args.get("days").and_then(|v| v.as_u64()).unwrap_or(30) as u32;
@@ -1035,7 +1044,121 @@ fn append_project_note(project_id: &str, content: &str) -> Result<String, String
         rusqlite::params![project_id, content],
     )
     .map_err(|e| e.to_string())?;
-    Ok("笔记已保存 ✅".to_string())
+    // 双写到项目分片档案（可拆除性）；失败不回滚笔记——DB 是事实源，backfill 可自愈
+    let note_id = conn.last_insert_rowid();
+    if let Err(e) = archive_note_append(&conn, note_id) {
+        db::log_event(
+            "mcp_tools",
+            "warn",
+            &format!("notes 档案双写失败（DB 已保存，backfill_notes_archive 可自愈）: {e}"),
+            None,
+        );
+        return Ok("笔记已保存 ✅（项目档案双写失败已记日志，可调 backfill_notes_archive 自愈）".to_string());
+    }
+    Ok("笔记已保存 ✅（已同步项目 .blueprint/notes-archive.jsonl）".to_string())
+}
+
+// ── notes 档案分片（可拆除性修复）─────────────────────────────────────────────
+// project_notes 是全系统唯一不在 git 的原创资产；双写到各项目
+// .blueprint/notes-archive.jsonl（JSONL 机器可重放重建 DB，即「重生配方」）。
+// 归宿按项目分片而非炼境仓库集中存放：路径解析可靠（复用登记路径防护）、
+// 可拆除性按项目成立、子项目会话（含 DSH）可直读自家档案。
+
+static NOTES_ARCHIVE_LOCK: std::sync::Mutex<()> = std::sync::Mutex::new(());
+
+/// 单条笔记 → JSONL 行（含 project_id，档案自含，脱离文件位置也可重建）
+fn note_jsonl_line(id: i64, project_id: &str, source: &str, content: &str, created_at: &str) -> String {
+    json!({
+        "id": id,
+        "project_id": project_id,
+        "source": source,
+        "content": content,
+        "created_at": created_at,
+    })
+    .to_string()
+}
+
+fn notes_archive_path(
+    conn: &rusqlite::Connection,
+    project_id: &str,
+) -> Result<std::path::PathBuf, String> {
+    let root = crate::mcp_inject::project_root_with_conn(conn, project_id)?;
+    Ok(root.join(".blueprint").join("notes-archive.jsonl"))
+}
+
+/// 追加单条到项目分片档案。路径无效（死登记/空路径）返回 Err，由调用方降级处理
+fn archive_note_append(conn: &rusqlite::Connection, note_id: i64) -> Result<(), String> {
+    let (pid, source, content, created_at): (String, String, String, String) = conn
+        .query_row(
+            "SELECT project_id, source, content, created_at FROM project_notes WHERE id = ?1",
+            [note_id],
+            |r| Ok((r.get(0)?, r.get(1)?, r.get(2)?, r.get(3)?)),
+        )
+        .map_err(|e| e.to_string())?;
+    let path = notes_archive_path(conn, &pid)?;
+    let _guard = NOTES_ARCHIVE_LOCK.lock().map_err(|e| e.to_string())?;
+    if let Some(dir) = path.parent() {
+        std::fs::create_dir_all(dir).map_err(|e| e.to_string())?;
+    }
+    use std::io::Write;
+    let mut f = std::fs::OpenOptions::new()
+        .create(true)
+        .append(true)
+        .open(&path)
+        .map_err(|e| e.to_string())?;
+    writeln!(f, "{}", note_jsonl_line(note_id, &pid, &source, &content, &created_at))
+        .map_err(|e| e.to_string())?;
+    Ok(())
+}
+
+/// 全量重建所有项目的分片档案（幂等，DB 为事实源整文件重写）
+fn backfill_notes_archive(conn: &rusqlite::Connection) -> Result<String, String> {
+    let mut stmt = conn
+        .prepare(
+            "SELECT id, project_id, source, content, created_at
+             FROM project_notes ORDER BY project_id, id",
+        )
+        .map_err(|e| e.to_string())?;
+    let rows: Vec<(i64, String, String, String, String)> = stmt
+        .query_map([], |r| Ok((r.get(0)?, r.get(1)?, r.get(2)?, r.get(3)?, r.get(4)?)))
+        .map_err(|e| e.to_string())?
+        .filter_map(|r| r.ok())
+        .collect();
+
+    let mut by_project: std::collections::BTreeMap<String, Vec<String>> = std::collections::BTreeMap::new();
+    for (id, pid, source, content, created_at) in &rows {
+        by_project
+            .entry(pid.clone())
+            .or_default()
+            .push(note_jsonl_line(*id, pid, source, content, created_at));
+    }
+
+    let _guard = NOTES_ARCHIVE_LOCK.lock().map_err(|e| e.to_string())?;
+    let mut report = String::from("## notes 档案回填（全量重建）\n\n");
+    let (mut archived, mut skipped) = (0usize, 0usize);
+    for (pid, lines) in &by_project {
+        match notes_archive_path(conn, pid) {
+            Ok(path) => {
+                if let Some(dir) = path.parent() {
+                    std::fs::create_dir_all(dir).map_err(|e| e.to_string())?;
+                }
+                std::fs::write(&path, lines.join("\n") + "\n").map_err(|e| e.to_string())?;
+                report.push_str(&format!("- ✅ {}：{} 条 → {}\n", pid, lines.len(), path.display()));
+                archived += 1;
+            }
+            Err(e) => {
+                report.push_str(&format!("- ⚠️ {}：跳过（{}），{} 条仅存 DB\n", pid, e, lines.len()));
+                skipped += 1;
+            }
+        }
+    }
+    report.push_str(&format!(
+        "\n共 {} 条笔记；{} 个项目已归档，{} 个跳过（跳过项待修复登记路径后重跑即可）。",
+        rows.len(),
+        archived,
+        skipped
+    ));
+    Ok(report)
 }
 
 fn get_project_snapshots(project_id: &str, days: u32) -> Result<String, String> {
@@ -1303,6 +1426,135 @@ mod tests {
         }
     }
 
+    /// notes 档案测试用最小 schema（in-memory 或文件库共用）
+    fn setup_notes_schema(conn: &rusqlite::Connection) {
+        conn.execute_batch(
+            "CREATE TABLE IF NOT EXISTS project_notes (
+                id         INTEGER PRIMARY KEY AUTOINCREMENT,
+                project_id TEXT NOT NULL,
+                source     TEXT NOT NULL DEFAULT 'mcp',
+                content    TEXT NOT NULL,
+                created_at TEXT DEFAULT (datetime('now', 'localtime'))
+             );
+             CREATE TABLE IF NOT EXISTS project_workspaces (
+                id TEXT PRIMARY KEY, profile_id TEXT,
+                win_path TEXT, wsl_path TEXT, platform TEXT
+             );
+             CREATE TABLE IF NOT EXISTS settings (key TEXT PRIMARY KEY, value TEXT);",
+        )
+        .unwrap();
+    }
+
+    fn temp_base(tag: &str) -> std::path::PathBuf {
+        let base = std::env::temp_dir().join(format!("lianjing_notes_{tag}_{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&base);
+        std::fs::create_dir_all(&base).unwrap();
+        base
+    }
+
+    #[test]
+    fn notes_archive_dual_write_line_matches_db() {
+        let conn = rusqlite::Connection::open_in_memory().unwrap();
+        setup_notes_schema(&conn);
+        let base = temp_base("dual");
+        conn.execute(
+            "INSERT INTO project_workspaces (id, win_path) VALUES ('p1', ?1)",
+            [base.to_str().unwrap()],
+        )
+        .unwrap();
+        conn.execute(
+            "INSERT INTO project_notes (project_id, content) VALUES ('p1', '含换行\n与中文的内容')",
+            [],
+        )
+        .unwrap();
+        let note_id = conn.last_insert_rowid();
+        archive_note_append(&conn, note_id).expect("双写应成功");
+
+        let file = base.join(".blueprint").join("notes-archive.jsonl");
+        let text = std::fs::read_to_string(&file).unwrap();
+        let lines: Vec<&str> = text.lines().collect();
+        assert_eq!(lines.len(), 1, "应恰好一行");
+        let v: Value = serde_json::from_str(lines[0]).expect("尾行应为合法 JSON");
+        assert_eq!(v["content"], "含换行\n与中文的内容");
+        assert_eq!(v["project_id"], "p1");
+        assert_eq!(v["id"], note_id);
+    }
+
+    #[test]
+    fn notes_backfill_rebuilds_and_skips_dead_registration() {
+        let conn = rusqlite::Connection::open_in_memory().unwrap();
+        setup_notes_schema(&conn);
+        let base = temp_base("backfill");
+        conn.execute(
+            "INSERT INTO project_workspaces (id, win_path) VALUES ('good', ?1)",
+            [base.to_str().unwrap()],
+        )
+        .unwrap();
+        // 死登记：空路径（2026-07-15 空路径污染同款场景，必须跳过而非写进 cwd）
+        conn.execute("INSERT INTO project_workspaces (id, win_path) VALUES ('dead', '')", []).unwrap();
+        for i in 0..3 {
+            conn.execute(
+                "INSERT INTO project_notes (project_id, content) VALUES ('good', ?1)",
+                [format!("note-{i}")],
+            )
+            .unwrap();
+        }
+        conn.execute("INSERT INTO project_notes (project_id, content) VALUES ('dead', 'x')", []).unwrap();
+
+        let report = backfill_notes_archive(&conn).expect("回填应成功");
+        let file = base.join(".blueprint").join("notes-archive.jsonl");
+        let count = std::fs::read_to_string(&file).unwrap().lines().count();
+        assert_eq!(count, 3, "good 项目 JSONL 行数应等于其表行数");
+        assert!(report.contains("⚠️ dead"), "死登记应被跳过并报告: {report}");
+
+        // 幂等：重跑后行数不变（整文件重写而非追加）
+        backfill_notes_archive(&conn).unwrap();
+        let count2 = std::fs::read_to_string(&file).unwrap().lines().count();
+        assert_eq!(count2, 3, "重跑不应翻倍");
+    }
+
+    #[test]
+    fn notes_archive_concurrent_appends_no_interleave() {
+        let base = temp_base("concurrent");
+        let db_path = base.join("test.db");
+        {
+            let conn = rusqlite::Connection::open(&db_path).unwrap();
+            setup_notes_schema(&conn);
+            conn.execute(
+                "INSERT INTO project_workspaces (id, win_path) VALUES ('p1', ?1)",
+                [base.to_str().unwrap()],
+            )
+            .unwrap();
+            for i in 0..8 {
+                conn.execute(
+                    "INSERT INTO project_notes (project_id, content) VALUES ('p1', ?1)",
+                    [format!("并发内容较长以放大交错概率-{i}-{}", "x".repeat(500))],
+                )
+                .unwrap();
+            }
+        }
+        let handles: Vec<_> = (1..=8)
+            .map(|note_id| {
+                let p = db_path.clone();
+                std::thread::spawn(move || {
+                    let conn = rusqlite::Connection::open(&p).unwrap();
+                    archive_note_append(&conn, note_id).expect("并发追加应成功");
+                })
+            })
+            .collect();
+        for h in handles {
+            h.join().unwrap();
+        }
+        let file = base.join(".blueprint").join("notes-archive.jsonl");
+        let text = std::fs::read_to_string(&file).unwrap();
+        let lines: Vec<&str> = text.lines().collect();
+        assert_eq!(lines.len(), 8, "8 线程应产出 8 行");
+        for l in &lines {
+            let v: Value = serde_json::from_str(l).expect("每行都应是完整 JSON（无交错）");
+            assert_eq!(v["project_id"], "p1");
+        }
+    }
+
     #[test]
     fn apply_onboarding_pack_schema_requires_project_id() {
         let result = tools_list_result();