diff --git a/crates/storage/src/database.rs b/crates/storage/src/database.rs
index 06de39f..4501934 100644
--- a/crates/storage/src/database.rs
+++ b/crates/storage/src/database.rs
@@ -286,7 +286,7 @@ pub async fn insert_task(
 
 pub async fn list_tasks(pool: &SqlitePool) -> Result<Vec<TaskRow>> {
     let rows =
-        sqlx::query("SELECT id, text, bucket, list_id, effort, done, done_at, created_at, source_transcript_id FROM tasks ORDER BY created_at DESC")
+        sqlx::query("SELECT id, text, bucket, list_id, effort, done, done_at, created_at, source_transcript_id, parent_task_id FROM tasks WHERE parent_task_id IS NULL ORDER BY created_at DESC")
             .fetch_all(pool)
             .await
             .map_err(|e| KonError::StorageError(format!("List tasks failed: {e}")))?;
@@ -303,10 +303,115 @@ pub async fn list_tasks(pool: &SqlitePool) -> Result<Vec<TaskRow>> {
             done_at: r.get("done_at"),
             created_at: r.get("created_at"),
             source_transcript_id: r.get("source_transcript_id"),
+            parent_task_id: r.get("parent_task_id"),
         })
         .collect())
 }
 
+pub async fn get_task_by_id(pool: &SqlitePool, id: &str) -> Result<Option<TaskRow>> {
+    let row = sqlx::query(
+        "SELECT id, text, bucket, list_id, effort, done, done_at, created_at, \
+         source_transcript_id, parent_task_id FROM tasks WHERE id = ?"
+    )
+    .bind(id)
+    .fetch_optional(pool)
+    .await
+    .map_err(|e| KonError::StorageError(format!("Get task failed: {e}")))?;
+
+    Ok(row.map(|r| TaskRow {
+        id: r.get("id"),
+        text: r.get("text"),
+        bucket: r.get("bucket"),
+        list_id: r.get("list_id"),
+        effort: r.get("effort"),
+        done: r.get("done"),
+        done_at: r.get("done_at"),
+        created_at: r.get("created_at"),
+        source_transcript_id: r.get("source_transcript_id"),
+        parent_task_id: r.get("parent_task_id"),
+    }))
+}
+
+pub async fn insert_subtask(
+    pool: &SqlitePool,
+    id: &str,
+    text: &str,
+    parent_task_id: &str,
+) -> Result<()> {
+    sqlx::query(
+        "INSERT INTO tasks (id, text, bucket, parent_task_id) VALUES (?, ?, 'inbox', ?)"
+    )
+    .bind(id)
+    .bind(text)
+    .bind(parent_task_id)
+    .execute(pool)
+    .await
+    .map_err(|e| KonError::StorageError(format!("Insert subtask failed: {e}")))?;
+    Ok(())
+}
+
+pub async fn list_subtasks(pool: &SqlitePool, parent_id: &str) -> Result<Vec<TaskRow>> {
+    let rows = sqlx::query(
+        "SELECT id, text, bucket, list_id, effort, done, done_at, created_at, \
+         source_transcript_id, parent_task_id \
+         FROM tasks WHERE parent_task_id = ? ORDER BY created_at ASC"
+    )
+    .bind(parent_id)
+    .fetch_all(pool)
+    .await
+    .map_err(|e| KonError::StorageError(format!("List subtasks failed: {e}")))?;
+
+    Ok(rows.into_iter().map(|r| TaskRow {
+        id: r.get("id"),
+        text: r.get("text"),
+        bucket: r.get("bucket"),
+        list_id: r.get("list_id"),
+        effort: r.get("effort"),
+        done: r.get("done"),
+        done_at: r.get("done_at"),
+        created_at: r.get("created_at"),
+        source_transcript_id: r.get("source_transcript_id"),
+        parent_task_id: r.get("parent_task_id"),
+    }).collect())
+}
+
+/// Mark a subtask done. If all siblings are now done, auto-complete the parent.
+pub async fn complete_subtask_and_check_parent(pool: &SqlitePool, subtask_id: &str) -> Result<()> {
+    sqlx::query("UPDATE tasks SET done = 1, done_at = datetime('now') WHERE id = ?")
+        .bind(subtask_id)
+        .execute(pool)
+        .await
+        .map_err(|e| KonError::StorageError(format!("Complete subtask failed: {e}")))?;
+
+    let parent_id: Option<String> = sqlx::query_scalar(
+        "SELECT parent_task_id FROM tasks WHERE id = ?"
+    )
+    .bind(subtask_id)
+    .fetch_one(pool)
+    .await
+    .map_err(|e| KonError::StorageError(format!("Get parent_task_id failed: {e}")))?;
+
+    let Some(pid) = parent_id else { return Ok(()); };
+
+    let pending: i64 = sqlx::query_scalar(
+        "SELECT COUNT(*) FROM tasks WHERE parent_task_id = ? AND done = 0"
+    )
+    .bind(&pid)
+    .fetch_one(pool)
+    .await
+    .map_err(|e| KonError::StorageError(format!("Count pending subtasks failed: {e}")))?;
+
+    if pending == 0 {
+        sqlx::query("UPDATE tasks SET done = 1, done_at = datetime('now') WHERE id = ?")
+            .bind(&pid)
+            .execute(pool)
+            .await
+            .map_err(|e| KonError::StorageError(format!("Auto-complete parent failed: {e}")))?;
+    }
+
+    Ok(())
+}
+
 pub async fn complete_task(pool: &SqlitePool, id: &str) -> Result<()> {
     sqlx::query("UPDATE tasks SET done = 1, done_at = datetime('now') WHERE id = ?")
         .bind(id)
@@ -379,6 +484,7 @@ pub struct TaskRow {
     pub done_at: Option<String>,
     pub created_at: String,
     pub source_transcript_id: Option<String>,
+    pub parent_task_id: Option<String>,
 }
 
 fn transcript_row_from(r: &sqlx::sqlite::SqliteRow) -> TranscriptRow {
@@ -552,6 +658,33 @@ mod tests {
         assert!(tasks.is_empty());
     }
 
+    #[tokio::test]
+    async fn subtask_crud_roundtrip() {
+        let pool = test_pool().await;
+        insert_task(&pool, "p1", "Write report", "inbox", None).await.unwrap();
+        insert_subtask(&pool, "s1", "Open document", "p1").await.unwrap();
+        insert_subtask(&pool, "s2", "Write introduction", "p1").await.unwrap();
+
+        // list_tasks must exclude subtasks
+        let top_level = list_tasks(&pool).await.unwrap();
+        assert_eq!(top_level.len(), 1);
+        assert_eq!(top_level[0].id, "p1");
+
+        // list_subtasks returns both children
+        let subs = list_subtasks(&pool, "p1").await.unwrap();
+        assert_eq!(subs.len(), 2);
+
+        // completing s1 should NOT auto-complete parent (s2 still pending)
+        complete_subtask_and_check_parent(&pool, "s1").await.unwrap();
+        let parent = get_task_by_id(&pool, "p1").await.unwrap().unwrap();
+        assert!(!parent.done, "parent should not be done yet");
+
+        // completing s2 SHOULD auto-complete parent
+        complete_subtask_and_check_parent(&pool, "s2").await.unwrap();
+        let parent = get_task_by_id(&pool, "p1").await.unwrap().unwrap();
+        assert!(parent.done, "parent should auto-complete when all children done");
+    }
+
     #[tokio::test]
     async fn settings_crud_roundtrip() {
         let pool = test_pool().await;
diff --git a/crates/storage/src/lib.rs b/crates/storage/src/lib.rs
index b4ed5be..e17f398 100644
--- a/crates/storage/src/lib.rs
+++ b/crates/storage/src/lib.rs
@@ -3,10 +3,11 @@ pub mod file_storage;
 pub mod migrations;
 
 pub use database::{
-    add_dictionary_entry, complete_task, count_transcripts, delete_dictionary_entry,
-    delete_task, delete_transcript, get_setting, get_transcript, init, insert_task,
-    insert_transcript, list_dictionary, list_recent_errors, list_tasks, list_transcripts,
-    list_transcripts_paged, log_error, search_transcripts, set_setting, update_transcript,
-    DictionaryEntry, ErrorLogRow, InsertTranscriptParams, TaskRow, TranscriptRow,
+    add_dictionary_entry, complete_subtask_and_check_parent, complete_task, count_transcripts,
+    delete_dictionary_entry, delete_task, delete_transcript, get_setting, get_task_by_id,
+    get_transcript, init, insert_subtask, insert_task, insert_transcript, list_dictionary,
+    list_recent_errors, list_subtasks, list_tasks, list_transcripts, list_transcripts_paged,
+    log_error, search_transcripts, set_setting, update_transcript, DictionaryEntry, ErrorLogRow,
+    InsertTranscriptParams, TaskRow, TranscriptRow,
 };
 pub use file_storage::{app_data_dir, crashes_dir, database_path, logs_dir, recordings_dir};