fix(core,cli): unknown wire messages count is null, empty read_file path rejected

CHANGELOG.md

@@ -9,6 +9,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [0.8.1] — 2026-10-09
 
+### Fixed
+- The usage report no longer renders an absent per-step `messages` count as a measured `0`; it is `null` in the status JSON when unknown (found by the pre-tag scan).
+- `read_file` rejects an empty `path` with a clear message instead of a confusing "is a directory" error.
+
 ### Added
 - `tole status` and the serve status JSON now report token usage, cache-hit rate and a per-step request-size split (system+tools vs history, stored per step under `tole_wire` in the usage record); `fact/mission` gains `cached_tokens`. Instrumentation only: the wire, budgets and durable entry shapes are unchanged (#211, part 1 of 3).
 

crates/tole-cli/src/usage_report.rs

@@ -22,7 +22,9 @@ pub struct WirePoint {
     pub system_chars: u64,
     pub tools_chars: u64,
     pub history_chars: u64,
-    pub messages: u64,
+    /// Message count of the request; `None` when the record does not carry it
+    /// (unknown is never rendered as a measured zero).
+    pub messages: Option<u64>,
 }
 
 #[derive(Debug, Clone, PartialEq)]
@@ -101,7 +103,7 @@ fn wire_of(u: &Value) -> Option<WirePoint> {
         system_chars,
         tools_chars,
         history_chars,
-        messages: w.get("messages").and_then(Value::as_u64).unwrap_or(0),
+        messages: w.get("messages").and_then(Value::as_u64),
     })
 }
 
@@ -417,4 +419,14 @@ mod tests {
         assert_eq!(r.prompt_tokens, 0);
         assert!(r.wire_first.is_none());
     }
+
+    #[test]
+    fn missing_messages_is_unknown_not_zero() {
+        let r = usage_report(&[rec(
+            json!({"tole_wire": {"system_chars": 1, "tools_chars": 2, "history_chars": 3}}),
+        )]);
+        let w = r.wire_first.expect("wire point without messages is kept");
+        assert_eq!(w.messages, None);
+        assert_eq!(wire_json(&w)["messages"], Value::Null);
+    }
 }

crates/tole-core/src/read_file.rs

@@ -44,6 +44,9 @@ impl ReadFileTool {
     /// also an escape. Errors distinguish escape from plain not-found so
     /// the model gets actionable feedback.
     fn jailed(&self, rel: &str) -> Result<PathBuf, String> {
+        if rel.is_empty() {
+            return Err("read_file: path is empty".to_string());
+        }
         let rel_path = Path::new(rel);
         // Component-based validation (uniform with the other file tools;
         // CodeCora scan #6/#12): drive-prefixed/rooted Windows relatives
@@ -207,6 +210,13 @@ mod tests {
         assert_eq!(out["bytes"], json!(5));
     }
 
+    #[test]
+    fn rejects_empty_path() {
+        let t = ReadFileTool::new(tmpdir("empty"));
+        let err = t.execute(json!({ "path": "" })).unwrap_err();
+        assert!(err.to_string().contains("path is empty"), "{err}");
+    }
+
     #[test]
     fn rejects_absolute_and_traversal() {
         let dir = tmpdir("jail");