fix(proxy-manager): correct singleton lifecycle and simplify to a plain Mutex

reset() eagerly rebuilt the ProxyManager singleton immediately,
capturing env vars before a caller could set them for the next
request. PHP's reset() just nulls the static instance; getInstance()
lazily constructs on next use. Match that so proxy env vars set after
reset() are observed.

get_instance() also ensured the singleton was constructed under its
own lock, dropped that lock, and returned the bare Mutex; every caller
then took a second, independent lock. A reset() landing in that gap
would leave the caller observing None and panicking on
.as_ref().unwrap(), a state the old eager-reconstructing reset() could
not produce. Return the already-locked MutexGuard from get_instance()
instead, so construction and use happen under one lock, and update all
call sites accordingly.

Holding that guard across a loop body then deadlocked in
diagnose_command, since check_http_proxy transitively re-enters
get_instance() via HttpDownloader -> CurlDownloader, and
std::sync::Mutex is not reentrant. Re-acquire the lock fresh each
iteration with a short-lived guard instead.

Finally, Mutex::new is a const fn, so the OnceLock wrapper around it
was unnecessary indirection; a bare static Mutex<Option<ProxyManager>>
initializes to the same state without the get_or_init/get dance.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

1 files changed, 9 insertions, 18 deletions

diff --git a/crates/shirabe/tests/util/http/proxy_manager_test.rs b/crates/shirabe/tests/util/http/proxy_manager_test.rs
index 7beafe19..d37a1fd8 100644
--- a/crates/shirabe/tests/util/http/proxy_manager_test.rs
+++ b/crates/shirabe/tests/util/http/proxy_manager_test.rs
@@ -46,21 +46,18 @@ fn test_instantiation() {
     // PHP compares object identity (===); the value-based Rust singleton exposes a per-instance
     // generation id instead, which changes only when a new ProxyManager is constructed.
     let original_instance = {
-        let mutex = ProxyManager::get_instance();
-        let guard = mutex.lock().unwrap();
+        let guard = ProxyManager::get_instance();
         guard.as_ref().unwrap().__generation()
     };
     let same_instance = {
-        let mutex = ProxyManager::get_instance();
-        let guard = mutex.lock().unwrap();
+        let guard = ProxyManager::get_instance();
         guard.as_ref().unwrap().__generation()
     };
     assert_eq!(original_instance, same_instance);
 
     ProxyManager::reset();
     let new_instance = {
-        let mutex = ProxyManager::get_instance();
-        let guard = mutex.lock().unwrap();
+        let guard = ProxyManager::get_instance();
         guard.as_ref().unwrap().__generation()
     };
     assert_ne!(same_instance, new_instance);
@@ -74,8 +71,7 @@ fn test_get_proxy_for_request_throws_on_bad_proxy_url() {
 
     Platform::put_env("http_proxy", "localhost");
     ProxyManager::reset();
-    let mutex = ProxyManager::get_instance();
-    let guard = mutex.lock().unwrap();
+    let guard = ProxyManager::get_instance();
     let proxy_manager = guard.as_ref().unwrap();
 
     assert!(
@@ -126,8 +122,7 @@ fn test_lowercase_overrides_uppercase() {
         }
         ProxyManager::reset();
 
-        let mutex = ProxyManager::get_instance();
-        let guard = mutex.lock().unwrap();
+        let guard = ProxyManager::get_instance();
         let proxy = guard.as_ref().unwrap().get_proxy_for_request(url).unwrap();
         assert_eq!(expected_url, proxy.get_status(None).unwrap());
     }
@@ -161,8 +156,7 @@ fn test_cgi_proxy_is_only_used_when_no_http_proxy() {
         }
         ProxyManager::reset();
 
-        let mutex = ProxyManager::get_instance();
-        let guard = mutex.lock().unwrap();
+        let guard = ProxyManager::get_instance();
         let proxy = guard
             .as_ref()
             .unwrap()
@@ -180,8 +174,7 @@ fn test_no_http_proxy_does_not_use_https_proxy() {
 
     Platform::put_env("https_proxy", "https://proxy.com:443");
     ProxyManager::reset();
-    let mutex = ProxyManager::get_instance();
-    let guard = mutex.lock().unwrap();
+    let guard = ProxyManager::get_instance();
     let proxy = guard
         .as_ref()
         .unwrap()
@@ -198,8 +191,7 @@ fn test_no_https_proxy_does_not_use_http_proxy() {
 
     Platform::put_env("http_proxy", "http://proxy.com:80");
     ProxyManager::reset();
-    let mutex = ProxyManager::get_instance();
-    let guard = mutex.lock().unwrap();
+    let guard = ProxyManager::get_instance();
     let proxy = guard
         .as_ref()
         .unwrap()
@@ -280,8 +272,7 @@ fn test_get_proxy_for_request() {
         }
         ProxyManager::reset();
 
-        let mutex = ProxyManager::get_instance();
-        let guard = mutex.lock().unwrap();
+        let guard = ProxyManager::get_instance();
         let proxy = guard.as_ref().unwrap().get_proxy_for_request(url).unwrap();
 
         assert_eq!(options.as_ref(), proxy.get_context_options());