refactor(env): route Shirabe's own env reads through the shim

These sites have no PHP counterpart to mirror, so they read std::env
directly. Going through the shim's getenv() keeps every environment
read in one place and lets a lint forbid the direct form.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

2 files changed, 4 insertions, 3 deletions

diff --git a/crates/shirabe/src/main.rs b/crates/shirabe/src/main.rs
index c4d9d313..fb0b31f1 100644
--- a/crates/shirabe/src/main.rs
+++ b/crates/shirabe/src/main.rs
@@ -5,9 +5,10 @@ use std::io::IsTerminal as _;
 
 /// Initialize a tracing subscriber from the environment variable `$SHIRABE_TRACING`.
 fn init_tracing() {
-    let Ok(directives) = std::env::var("SHIRABE_TRACING") else {
+    let Some(directives) = shirabe_php_shim::getenv("SHIRABE_TRACING") else {
         return;
     };
+    let directives = directives.to_string_lossy();
     if directives.is_empty() {
         return;
     }
diff --git a/crates/shirabe/src/signal.rs b/crates/shirabe/src/signal.rs
index 26297cc7..6ae8dfc1 100644
--- a/crates/shirabe/src/signal.rs
+++ b/crates/shirabe/src/signal.rs
@@ -172,7 +172,7 @@ mod tests {
 
     #[test]
     fn exit_with_last_signal_kills_by_the_signal() {
-        if std::env::var("SIGNAL_TEST_CHILD").is_ok() {
+        if shirabe_php_shim::getenv("SIGNAL_TEST_CHILD").is_some() {
             let signals = SignalSubscription::new();
             raise_sigint();
             signals.exit_with_last_signal();
@@ -188,7 +188,7 @@ mod tests {
 
     #[test]
     fn the_default_disposition_returns_once_no_subscription_is_left() {
-        if std::env::var("SIGNAL_TEST_CHILD").is_ok() {
+        if shirabe_php_shim::getenv("SIGNAL_TEST_CHILD").is_some() {
             drop(SignalSubscription::new());
             raise_sigint();
             unreachable!("SIGINT must terminate the process");