test(diff): add unit test for cursor-line editor open

- add diff_component_opens_editor_at_cursor_line verifying that
  OpenExternalEditor carries the new_lineno of the line the cursor
  is on, not the hunk start
- add changelog entry for the editor goto-line feature

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Co-Authored-By: Claude Code 2.1.143 (Claude Code)
Signed-Off-By: Paal Øye-Strømme <paal.o.eye@gmail.com>

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Changed
 * use [tombi](https://github.com/tombi-toml/tombi) for all toml file formatting
 * open the external editor from the status diff view [[@WaterWhisperer](https://github.com/WaterWhisperer)] ([#2805](https://github.com/gitui-org/gitui/issues/2805))
+* open external editor at the cursor line from any diff view (status, log, blame), with editor-specific goto syntax (Helix, VS Code, vi-style) [@paaloeye](https://github.com/paaloeye) ([#2952](https://github.com/gitui-org/gitui/pull/2952))
 
 ### Fixes
 * crash when opening submodule ([#2895](https://github.com/gitui-org/gitui/issues/2895))

src/components/diff.rs

@@ -1082,4 +1082,80 @@ mod tests {
 				if path == "src/main.rs"
 		));
 	}
+
+	#[test]
+	fn diff_component_opens_editor_at_cursor_line() {
+		use asyncgit::sync::diff::{DiffLinePosition, Hunk};
+		use asyncgit::FileDiff;
+
+		let env = Environment::test_env();
+		let mut comp = DiffComponent::new(&env, false);
+		comp.focus(true);
+		comp.current.path = String::from("src/main.rs");
+
+		// build a minimal FileDiff: one hunk with a header line and
+		// two content lines at known new_lineno values
+		let hunk = Hunk {
+			header_hash: 0,
+			lines: vec![
+				DiffLine {
+					content: "@@ -1,2 +1,2 @@".into(),
+					line_type: DiffLineType::Header,
+					position: DiffLinePosition {
+						old_lineno: None,
+						new_lineno: None,
+					},
+				},
+				DiffLine {
+					content: "context".into(),
+					line_type: DiffLineType::None,
+					position: DiffLinePosition {
+						old_lineno: Some(1),
+						new_lineno: Some(1),
+					},
+				},
+				DiffLine {
+					content: "added line".into(),
+					line_type: DiffLineType::Add,
+					position: DiffLinePosition {
+						old_lineno: None,
+						new_lineno: Some(2),
+					},
+				},
+			],
+		};
+		let file_diff = FileDiff {
+			hunks: vec![hunk],
+			lines: 3,
+			untracked: false,
+			sizes: (0, 0),
+			size_delta: 0,
+		};
+		comp.update(String::from("src/main.rs"), false, file_diff);
+
+		// move cursor to the Add line (index 2 in the flat list)
+		comp.move_selection(ScrollType::Down);
+		comp.move_selection(ScrollType::Down);
+
+		let event = Event::Key(KeyEvent::new(
+			KeyCode::Char('e'),
+			KeyModifiers::empty(),
+		));
+		assert!(matches!(
+			comp.event(&event).unwrap(),
+			EventState::Consumed
+		));
+
+		let queued = env.queue.pop();
+		assert!(
+			matches!(
+				queued,
+				Some(InternalEvent::OpenExternalEditor(
+					Some(_),
+					Some(2)
+				))
+			),
+			"expected OpenExternalEditor with line Some(2)"
+		);
+	}
 }