feat(gamification): flag cascade-completed parents as auto_completed

complete_subtask_and_check_parent now sets auto_completed = 1 on the
parent when it closes via the cascade. The subtask UPDATE itself
remains at the default 0, so explicit user taps still count toward
the Phase 8 daily total.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/storage/src/database.rs

@@ -451,7 +451,13 @@ pub async fn complete_subtask_and_check_parent(pool: &SqlitePool, subtask_id: &s
                 })?;
 
         if pending == 0 {
-            sqlx::query("UPDATE tasks SET done = 1, done_at = datetime('now') WHERE id = ?")
+            // Phase 8: flag the cascade so the daily-count query can exclude
+            // it. The subtask UPDATE (above) stays at auto_completed = 0 — the
+            // user explicitly ticked it, so it counts.
+            sqlx::query(
+                "UPDATE tasks SET done = 1, done_at = datetime('now'), auto_completed = 1 \
+                 WHERE id = ?",
+            )
             .bind(&pid)
             .execute(&mut *tx)
             .await
@@ -2016,4 +2022,59 @@ mod tests {
         let missing = get_setting(&pool, "nonexistent").await.unwrap();
         assert!(missing.is_none());
     }
+
+    #[tokio::test]
+    async fn cascade_sets_auto_completed_on_parent_only() {
+        let pool = test_pool().await;
+
+        // Parent + two subtasks.
+        insert_task(
+            &pool,
+            "parent",
+            "Parent task",
+            "inbox",
+            None,
+            None,
+            None,
+            None,
+        )
+        .await
+        .unwrap();
+        insert_subtask(&pool, "s1", "Step 1", "parent")
+            .await
+            .unwrap();
+        insert_subtask(&pool, "s2", "Step 2", "parent")
+            .await
+            .unwrap();
+
+        complete_subtask_and_check_parent(&pool, "s1")
+            .await
+            .unwrap();
+        complete_subtask_and_check_parent(&pool, "s2")
+            .await
+            .unwrap();
+
+        // Parent auto-closed.
+        let parent_auto: i64 =
+            sqlx::query_scalar("SELECT auto_completed FROM tasks WHERE id = 'parent'")
+                .fetch_one(&pool)
+                .await
+                .unwrap();
+        assert_eq!(
+            parent_auto, 1,
+            "parent closed by cascade must be auto_completed = 1"
+        );
+
+        // Subtasks themselves are manual.
+        let s1_auto: i64 = sqlx::query_scalar("SELECT auto_completed FROM tasks WHERE id = 's1'")
+            .fetch_one(&pool)
+            .await
+            .unwrap();
+        let s2_auto: i64 = sqlx::query_scalar("SELECT auto_completed FROM tasks WHERE id = 's2'")
+            .fetch_one(&pool)
+            .await
+            .unwrap();
+        assert_eq!(s1_auto, 0, "subtask completion is manual");
+        assert_eq!(s2_auto, 0, "subtask completion is manual");
+    }
 }