refactor(promise): rewrite promise bodies to async/await

Mechanically convert promise-returning function bodies to async/await:
resolve() returns the value directly, forwarding calls get .await, and
simple .then chains become await sequences. Also collapse the installer
double-Option (Result<Option<Option<PhpMixed>>> -> Result<Option<PhpMixed>>).

Hard spots that depend on the Loop::wait / job-machine boundary
(accept/reject orchestration, closures capturing &mut self, batch waits)
are left intact and marked with TODO(phase-c-promise) for manual porting.
The crate does not compile yet; traits still need #[async_trait].

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

1 files changed, 13 insertions, 7 deletions

diff --git a/crates/shirabe/src/downloader/xz_downloader.rs b/crates/shirabe/src/downloader/xz_downloader.rs
index 6cc960e..d15287d 100644
--- a/crates/shirabe/src/downloader/xz_downloader.rs
+++ b/crates/shirabe/src/downloader/xz_downloader.rs
@@ -64,7 +64,7 @@ impl XzDownloader {
             (),
         )? == 0
         {
-            return Ok(shirabe_external_packages::react::promise::resolve(None));
+            return Ok(None);
         }
 
         let process_error = format!(
@@ -89,7 +89,9 @@ impl crate::downloader::DownloaderInterface for XzDownloader {
         prev_package: Option<&dyn PackageInterface>,
         output: bool,
     ) -> Result<Option<PhpMixed>> {
-        self.inner.download(package, path, prev_package, output)
+        self.inner
+            .download(package, path, prev_package, output)
+            .await
     }
 
     async fn prepare(
@@ -99,7 +101,9 @@ impl crate::downloader::DownloaderInterface for XzDownloader {
         path: &str,
         prev_package: Option<&dyn PackageInterface>,
     ) -> Result<Option<PhpMixed>> {
-        self.inner.prepare(r#type, package, path, prev_package)
+        self.inner
+            .prepare(r#type, package, path, prev_package)
+            .await
     }
 
     async fn install(
@@ -108,7 +112,7 @@ impl crate::downloader::DownloaderInterface for XzDownloader {
         path: &str,
         output: bool,
     ) -> Result<Option<PhpMixed>> {
-        self.inner.install(package, path, output)
+        self.inner.install(package, path, output).await
     }
 
     async fn update(
@@ -117,7 +121,7 @@ impl crate::downloader::DownloaderInterface for XzDownloader {
         target: &dyn PackageInterface,
         path: &str,
     ) -> Result<Option<PhpMixed>> {
-        self.inner.update(initial, target, path)
+        self.inner.update(initial, target, path).await
     }
 
     async fn remove(
@@ -126,7 +130,7 @@ impl crate::downloader::DownloaderInterface for XzDownloader {
         path: &str,
         output: bool,
     ) -> Result<Option<PhpMixed>> {
-        self.inner.remove(package, path, output)
+        self.inner.remove(package, path, output).await
     }
 
     async fn cleanup(
@@ -136,6 +140,8 @@ impl crate::downloader::DownloaderInterface for XzDownloader {
         path: &str,
         prev_package: Option<&dyn PackageInterface>,
     ) -> Result<Option<PhpMixed>> {
-        self.inner.cleanup(r#type, package, path, prev_package)
+        self.inner
+            .cleanup(r#type, package, path, prev_package)
+            .await
     }
 }