huskies: merge 1238 bug worktree tests fail on macOS: tests clobber global HOME

server/src/chat/compact/transcript.rs

@@ -10,10 +10,55 @@ use std::path::{Path, PathBuf};
 /// replaced by `-` (e.g. `/workspace/.huskies/worktrees/1186` becomes
 /// `-workspace--huskies-worktrees-1186`).
 pub fn transcript_path(cwd: &Path, session_id: &str) -> PathBuf {
+    #[cfg(test)]
+    if let Some(home) = test_home::get() {
+        return transcript_path_under_home(&home, cwd, session_id);
+    }
     let home = std::env::var("HOME").unwrap_or_else(|_| "/home/huskies".to_string());
     transcript_path_under_home(Path::new(&home), cwd, session_id)
 }
 
+/// Per-thread `$HOME` override for tests, so a test can sandbox where
+/// [`transcript_path`] looks without mutating the process-global `$HOME`
+/// env var (which every thread shares, including unrelated `git`
+/// subprocesses spawned by other tests reading `$HOME` for
+/// `~/.gitconfig`). Thread-local storage gives each test's thread its own
+/// independent value — no lock, no serialization, no race, since
+/// `#[tokio::test]` (current-thread flavor, used throughout this crate)
+/// pins a test's whole async call graph to the one thread that set it.
+#[cfg(test)]
+pub(crate) mod test_home {
+    use std::cell::RefCell;
+    use std::path::{Path, PathBuf};
+
+    thread_local! {
+        static HOME: RefCell<Option<PathBuf>> = const { RefCell::new(None) };
+    }
+
+    /// Return the current thread's `$HOME` override, if one is set.
+    pub(crate) fn get() -> Option<PathBuf> {
+        HOME.with(|h| h.borrow().clone())
+    }
+
+    /// RAII guard: while held, this thread's [`super::transcript_path`]
+    /// calls resolve under the overridden home instead of the real
+    /// `$HOME`. Clears the override on drop.
+    pub(crate) struct HomeGuard;
+
+    impl Drop for HomeGuard {
+        fn drop(&mut self) {
+            HOME.with(|h| *h.borrow_mut() = None);
+        }
+    }
+
+    /// Override `$HOME` resolution for [`super::transcript_path`] calls
+    /// made on the current thread for the lifetime of the returned guard.
+    pub(crate) fn set(home: &Path) -> HomeGuard {
+        HOME.with(|h| *h.borrow_mut() = Some(home.to_path_buf()));
+        HomeGuard
+    }
+}
+
 /// Same as [`transcript_path`] but takes an explicit `$HOME` directory,
 /// keeping the path-joining logic testable without mutating process env vars.
 fn transcript_path_under_home(home: &Path, cwd: &Path, session_id: &str) -> PathBuf {