Lots of changes... not done yet.

app/src/ai/tool_diagnostics.rs

@@ -0,0 +1,46 @@
+use std::backtrace::Backtrace;
+use std::ffi::OsStr;
+use std::sync::OnceLock;
+
+const ENV_VAR: &str = "GALAXY_TOOL_DIAGNOSTICS";
+
+fn env_value_is_enabled(value: Option<&OsStr>) -> bool {
+    value
+        .and_then(OsStr::to_str)
+        .is_some_and(|value| value == "1" || value.eq_ignore_ascii_case("true"))
+}
+
+pub(crate) fn is_enabled() -> bool {
+    static ENABLED: OnceLock<bool> = OnceLock::new();
+    *ENABLED.get_or_init(|| env_value_is_enabled(std::env::var_os(ENV_VAR).as_deref()))
+}
+
+pub(crate) fn capture_backtrace() -> Option<Backtrace> {
+    is_enabled().then(Backtrace::force_capture)
+}
+
+macro_rules! tool_debug {
+    ($($arg:tt)*) => {
+        if $crate::ai::tool_diagnostics::is_enabled() {
+            log::debug!("[tool-debug] {}", format_args!($($arg)*));
+        }
+    };
+}
+
+pub(crate) use tool_debug;
+
+#[cfg(test)]
+mod tests {
+    use std::ffi::OsStr;
+
+    use super::env_value_is_enabled;
+
+    #[test]
+    fn diagnostic_env_accepts_only_explicit_true_values() {
+        assert!(env_value_is_enabled(Some(OsStr::new("1"))));
+        assert!(env_value_is_enabled(Some(OsStr::new("TRUE"))));
+        assert!(!env_value_is_enabled(Some(OsStr::new("0"))));
+        assert!(!env_value_is_enabled(Some(OsStr::new("yes"))));
+        assert!(!env_value_is_enabled(None));
+    }
+}