Escape periods when converting globs

src/agent/coverage/src/allowlist.rs

@@ -140,6 +140,11 @@ impl AllowListLine {
 
 #[allow(clippy::single_char_pattern)]
 fn glob_to_regex(expr: &str) -> Result<Regex> {
+    // Treat `.` as literal, not match-any.
+    //
+    // Use character class syntax to avoid double-escaping.
+    let expr = expr.replace(".", r"[.]");
+
     // Don't make users escape Windows path separators.
     let expr = expr.replace(r"\", r"\\");
 

src/agent/coverage/src/allowlist/test-data/allow-all-glob-extension.txt

@@ -0,0 +1 @@
+a.*

src/agent/coverage/src/allowlist/tests.rs

@@ -99,3 +99,20 @@ fn test_allow_glob_except_commented() -> Result<()> {
 
     Ok(())
 }
+
+#[test]
+fn test_allow_glob_extension() -> Result<()> {
+    let text = include_str!("test-data/allow-all-glob-extension.txt");
+    let allowlist = AllowList::parse(text)?;
+
+    assert!(allowlist.is_allowed("a.c"));
+    assert!(allowlist.is_allowed("a.h"));
+
+    assert!(!allowlist.is_allowed("ac"));
+    assert!(!allowlist.is_allowed("ah"));
+
+    assert!(!allowlist.is_allowed("axc"));
+    assert!(!allowlist.is_allowed("axh"));
+
+    Ok(())
+}