Fix bug that the file content is cleared when updating status

docs/reviews/ai-review-result_bug-file-vanish_20260304.md

@@ -0,0 +1,36 @@
+# The result of review
+Fix bug that the file content is cleared when updating status (PR #8)
+
+## ❌CRITICAL
+Nothing.
+
+## 🔴HIGH
+Nothing.
+
+## 🟡MEDIUM
+Nothing.
+
+## 🔵LOW
+
+### Comment1: Silent error suppression in `update_status`
+`src/task.rs` - `update_status` method
+
+`let _ = self.update_frontmatter_preserving_body();` silently discards the `io::Result`. If writing fails (e.g. disk full), the file will have been moved to the new directory but its frontmatter (including `updated_at`) will remain stale with no indication to the caller. This is consistent with the existing pattern in the same method, but worth noting as a future improvement.
+
+### Comment2: Frontmatter delimiter ambiguity in body extraction
+`src/task.rs` - `update_frontmatter_preserving_body` method
+
+The body is extracted by searching for the first occurrence of `"\n---\n"` in the content after the opening delimiter. If a user writes `\n---\n` inside the markdown body (e.g. a YAML code block or a horizontal rule sequence), the extraction will silently truncate the body at that point. This is an inherent limitation of simple string-based frontmatter parsing, and unlikely to matter in practice given how the app is used.
+
+### Comment3: Verbose test setup line
+`src/task.rs` - `update_status_moves_file_between_directories` test
+`tests/integration_test.rs` - `forward_status_moves_md_file_to_next_directory` test
+
+```rust
+// Current: hard to read at a glance
+fs::write(task.file_path(), format!("{}{}", fs::read_to_string(task.file_path()).unwrap(), body)).unwrap();
+
+// Clearer:
+let existing = fs::read_to_string(task.file_path()).unwrap();
+fs::write(task.file_path(), format!("{}{}", existing, body)).unwrap();
+```

src/task.rs

@@ -160,7 +160,19 @@ impl Task {
         self.updated_at = Utc::now();
         let _ = fs::create_dir_all(Self::status_dir(&self.status));
         let _ = fs::rename(old_path, self.file_path());
-        let _ = self.save();
+        let _ = self.update_frontmatter_preserving_body();
+    }
+
+    /// Updates only the YAML frontmatter of the task file while preserving the markdown body.
+    fn update_frontmatter_preserving_body(&self) -> io::Result<()> {
+        let path = self.file_path();
+        let existing = fs::read_to_string(&path)?;
+        let yaml = serde_yaml::to_string(&self.frontmatter()).map_err(io::Error::other)?;
+        let body = existing
+            .strip_prefix("---\n")
+            .and_then(|s| s.find("\n---\n").map(|pos| &s[pos + 5..]))
+            .unwrap_or("");
+        fs::write(&path, format!("---\n{}---\n{}", yaml, body))
     }
 
     /// Sorts tasks by status group (TODO, DOING, DONE) and by `created_at` within each group.
@@ -272,9 +284,12 @@ mod tests {
 
     #[test]
     fn update_status_moves_file_between_directories() {
-        // GIVEN: a saved task with TODO status
+        // GIVEN: a saved task with TODO status and a markdown body appended to the file
         let mut task = Task::new("status move test".to_string());
         task.save().unwrap();
+        let body = "## Notes\n\nsome content here\n";
+        let existing = fs::read_to_string(task.file_path()).unwrap();
+        fs::write(task.file_path(), format!("{}{}", existing, body)).unwrap();
         let old_path = task.file_path();
         assert!(old_path.exists());
 
@@ -283,11 +298,13 @@ mod tests {
         let before_update = task.updated_at;
         task.update_status(TaskStatus::Doing);
 
-        // THEN: the file is moved to doing/ directory and updated_at is refreshed
+        // THEN: the file is moved to doing/ directory, updated_at is refreshed, and body content is preserved
         assert!(!old_path.exists());
         assert!(task.file_path().exists());
         assert!(task.file_path().to_str().unwrap().contains("/doing/"));
         assert!(task.updated_at > before_update);
+        let content = fs::read_to_string(task.file_path()).unwrap();
+        assert!(content.contains(body));
 
         let _ = fs::remove_file(task.file_path());
     }

tests/integration_test.rs

@@ -3,7 +3,7 @@ use rem_cli::app::App;
 use rem_cli::task::TaskStatus;
 use std::fs;
 
-/// Scenario 1: Adding a task via rem creates a new md file.
+/// Scenario: Adding a task via rem creates a new md file.
 ///
 /// Simulates pressing 'a', typing a task name, and pressing Enter.
 /// Verifies that a corresponding md file is created in the todo/ directory.
@@ -34,7 +34,7 @@ fn adding_task_creates_md_file() {
     let _ = fs::remove_file(file_path);
 }
 
-/// Scenario 2: Pressing 'n' moves the md file to the next status directory.
+/// Scenario: Pressing 'n' moves the md file to the next status directory.
 ///
 /// Creates a task, then presses 'n' to forward status from TODO to DOING.
 /// Verifies the file is moved from todo/ to doing/.
@@ -52,6 +52,9 @@ fn forward_status_moves_md_file_to_next_directory() {
         .expect("task should exist");
     let todo_path = task.file_path();
     assert!(todo_path.exists());
+    let body = "## Notes\n\nsome content here\n";
+    let existing = fs::read_to_string(&todo_path).unwrap();
+    fs::write(&todo_path, format!("{}{}", existing, body)).unwrap();
 
     // WHEN: navigate to the task and press 'n' to forward status (TODO -> DOING)
     let task_index = app.tasks.iter()
@@ -60,7 +63,7 @@ fn forward_status_moves_md_file_to_next_directory() {
     app.selected_index = Some(task_index);
     app.handle_key_event(KeyCode::Char('n'));
 
-    // THEN: the file is moved from todo/ to doing/
+    // THEN: the file is moved from todo/ to doing/, and body content is preserved
     assert!(!todo_path.exists(), "file should no longer exist in todo/");
     let task = app.tasks.iter()
         .find(|t| t.name == "forward status test")
@@ -69,12 +72,13 @@ fn forward_status_moves_md_file_to_next_directory() {
     let doing_path = task.file_path();
     assert!(doing_path.exists(), "file should exist in doing/");
     assert!(doing_path.to_str().unwrap().contains("/doing/"));
+    assert!(fs::read_to_string(&doing_path).unwrap().contains(body), "file body should be preserved after status update");
 
     // Cleanup
     let _ = fs::remove_file(doing_path);
 }
 
-/// Scenario 2 (reverse): Pressing 'N' moves the md file to the previous status directory.
+/// Scenario: Pressing 'N' moves the md file to the previous status directory.
 ///
 /// Creates a task in DOING status, then presses 'N' to backward status from DOING to TODO.
 /// Verifies the file is moved from doing/ to todo/.