tests: every test dir is removed when its test ends, pass or panic

Many test helpers removed their temp dir only before the test, or only
on pass, so runs left them behind: 117,000 filled /tmp (RAM here) and
stopped a mutation run. Each now holds a guard that removes the dir on
drop, unwind included; servers started on a test dir hold its guard
until they stop. A full cargo test --workspace leaves 0 dirs (859
before). just sweep-test-tmp stays for runs killed mid-test.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01T3gXMVt7XJPi6ens1or9Dj

crates/ledger-mcp/tests/oracle_mcp.rs

@@ -56,7 +56,31 @@ impl Drop for Mcp {
 
 static DIR_SEQ: AtomicU64 = AtomicU64::new(0);
 
-fn test_dir(name: &str) -> PathBuf {
+/// A test's dir and the folder beside it (`.inbox`),
+/// removed when the test ends, pass or panic.
+struct TestDir(PathBuf);
+
+impl std::ops::Deref for TestDir {
+    type Target = std::path::Path;
+    fn deref(&self) -> &std::path::Path {
+        &self.0
+    }
+}
+
+impl AsRef<std::path::Path> for TestDir {
+    fn as_ref(&self) -> &std::path::Path {
+        &self.0
+    }
+}
+
+impl Drop for TestDir {
+    fn drop(&mut self) {
+        let _ = std::fs::remove_dir_all(&self.0);
+        let _ = std::fs::remove_dir_all(format!("{}.inbox", self.0.display()));
+    }
+}
+
+fn test_dir(name: &str) -> TestDir {
     let n = DIR_SEQ.fetch_add(1, Ordering::Relaxed);
     let dir = std::env::temp_dir().join(format!(
         "ledger-mcp-oracle-{}-{name}-{n}",
@@ -64,7 +88,7 @@ fn test_dir(name: &str) -> PathBuf {
     ));
     let _ = std::fs::remove_dir_all(&dir);
     std::fs::create_dir_all(&dir).unwrap();
-    dir
+    TestDir(dir)
 }
 
 /// `wanderbooks.toml` for two 50/50 members on 3000/3001, cash 1000,
@@ -2249,19 +2273,10 @@ fn receipts_and_documents_round_trip() {
 #[test]
 fn uploads_up_to_25_mib_are_accepted_and_no_more() {
     const LIMIT: usize = 25 * 1024 * 1024;
+    // Over 50 MB of books: removed however the test ends, with its inbox
+    // (the system temp dir is often RAM, and a mutation run starts this
+    // test hundreds of times).
     let dir = test_dir("limits");
-    // Over 50 MB of books: removed however the test ends (the system temp
-    // dir is often RAM, and a mutation run starts this test hundreds of
-    // times).
-    struct Cleanup(Vec<PathBuf>);
-    impl Drop for Cleanup {
-        fn drop(&mut self) {
-            for d in &self.0 {
-                let _ = std::fs::remove_dir_all(d);
-            }
-        }
-    }
-    let _cleanup = Cleanup(vec![dir.clone(), inbox(&dir)]);
     let s = new_store(&dir);
     drop(s);
     let mut m = Mcp::start(&dir, "1000000.00");