feat(downloader): wire VcsDownloader subclasses via shared downloaders

Share downloaders as Rc<RefCell<dyn DownloaderInterface>> in
DownloadManager and make DownloaderInterface/VcsDownloader take
&mut self, matching PHP's mutable-by-reference downloader objects.
This lets Git/Svn/Hg/Fossil/Perforce implement VcsDownloader and route
download/install/update/prepare/cleanup through the trait instead of
todo!(), and wires the as_* downcast hooks end-to-end.

ChangeReportInterface::get_local_changes becomes &mut self since
FileDownloader downloads to a compare dir; get_commit_logs/reapply_changes
gain &mut self / Result to match the concrete implementations.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

1 files changed, 5 insertions, 7 deletions

diff --git a/crates/shirabe/src/command/status_command.rs b/crates/shirabe/src/command/status_command.rs
index 01c1b5e..457c546 100644
--- a/crates/shirabe/src/command/status_command.rs
+++ b/crates/shirabe/src/command/status_command.rs
@@ -128,13 +128,11 @@ impl StatusCommand {
                 Some(d) => d,
                 None => continue,
             };
-            // TODO(phase-b): downloader borrow lifetime tied to dm.borrow() temporary; restructure later.
-            let dm_borrow = dm.borrow();
-            let downloader: &dyn crate::downloader::DownloaderInterface =
-                match dm_borrow.get_downloader_for_package(package.clone())? {
-                    Some(d) => d,
-                    None => continue,
-                };
+            let downloader_handle = match dm.borrow().get_downloader_for_package(package.clone())? {
+                Some(d) => d,
+                None => continue,
+            };
+            let mut downloader = downloader_handle.borrow_mut();
 
             // TODO(phase-b): isinstance checks using ChangeReportInterface/VcsCapableDownloaderInterface/DvcsDownloaderInterface
             if let Some(change_reporter) = downloader.as_change_report_interface() {