replace ContainerRuntime CLI to Bollard crate (default: docker socket)

limit tool result to open router tool response (with truncated info for
ai)

Hard kill if graceful shutdown is too long

crates/herald-server/src/text.rs

@@ -0,0 +1,81 @@
+//! Small text helpers shared by the modules that log what the model answered and
+//! bound what the tools return to it.
+
+/// First `limit` characters of `text`, for logs.
+///
+/// Cuts on character boundaries, so the excerpt stays valid UTF-8, and marks a
+/// truncation with an ellipsis.
+pub fn excerpt(text: &str, limit: usize) -> String {
+    let mut chars = text.chars();
+    let excerpt = chars.by_ref().take(limit).collect::<String>();
+
+    if chars.next().is_some() {
+        return format!("{excerpt}…");
+    }
+
+    excerpt
+}
+
+/// Truncates `text` in place to at most `limit` bytes, cutting on a character
+/// boundary so the result stays valid UTF-8.
+///
+/// Returns `true` when something was dropped.
+pub fn truncate_bytes(text: &mut String, limit: usize) -> bool {
+    if text.len() <= limit {
+        return false;
+    }
+
+    let mut end = limit;
+    while !text.is_char_boundary(end) {
+        end -= 1;
+    }
+
+    text.truncate(end);
+
+    true
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn a_short_text_is_kept_as_is() {
+        assert_eq!(excerpt("abc", 3), "abc");
+    }
+
+    #[test]
+    fn a_long_text_is_truncated_and_marked() {
+        assert_eq!(excerpt("abcdef", 3), "abc…");
+    }
+
+    #[test]
+    fn truncation_cuts_on_character_boundaries() {
+        assert_eq!(excerpt("ééé", 2), "éé…");
+    }
+
+    #[test]
+    fn a_short_text_is_not_truncated() {
+        let mut text = String::from("abc");
+
+        assert!(!truncate_bytes(&mut text, 3));
+        assert_eq!(text, "abc");
+    }
+
+    #[test]
+    fn a_long_text_is_truncated_within_the_limit() {
+        let mut text = String::from("abcdef");
+
+        assert!(truncate_bytes(&mut text, 4));
+        assert_eq!(text, "abcd");
+    }
+
+    #[test]
+    fn byte_truncation_never_splits_a_character() {
+        let mut text = String::from("ééé");
+
+        // The limit falls in the middle of the second `é`: it is dropped.
+        assert!(truncate_bytes(&mut text, 3));
+        assert_eq!(text, "é");
+    }
+}