fix(pi): skip unparseable session lines instead of failing the read

CHANGELOG.md

@@ -2,6 +2,14 @@
 
 All notable changes to the Toolpath workspace are documented here.
 
+## Pi: skip unparseable lines instead of failing the read — 2026-07-08
+
+- **`toolpath-pi`** (0.6.1): Crashed or truncated Pi session files now load
+  gracefully. Previously, a truncated final line (invalid JSON) would fail
+  the entire session read; now unparseable lines are skipped with a warning
+  (matching `toolpath-codex`'s documented safe-reader policy). Header parsing
+  remains a hard error — a session without a parseable header has no identity.
+
 ## Derive: resolve duplicate step ids — 2026-07-01
 
 - **`toolpath-convo`** (0.11.1): `derive_path` now guarantees the derived

Cargo.toml

@@ -34,7 +34,7 @@ toolpath-cursor = { version = "0.2.0", path = "crates/toolpath-cursor" }
 toolpath-github = { version = "0.6.0", path = "crates/toolpath-github" }
 toolpath-dot = { version = "0.5.0", path = "crates/toolpath-dot" }
 toolpath-md = { version = "0.7.0", path = "crates/toolpath-md" }
-toolpath-pi = { version = "0.6.0", path = "crates/toolpath-pi" }
+toolpath-pi = { version = "0.6.1", path = "crates/toolpath-pi" }
 path-cli = { version = "0.14.0", path = "crates/path-cli" }
 pathbase-client = { version = "0.2.0", path = "crates/pathbase-client" }
 

crates/toolpath-pi/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "toolpath-pi"
-version = "0.6.0"
+version = "0.6.1"
 edition.workspace = true
 license.workspace = true
 repository = "https://github.com/empathic/toolpath"

crates/toolpath-pi/src/reader.rs

@@ -220,10 +220,12 @@ pub fn read_session_from_file(path: &Path) -> Result<PiSession> {
                         continue;
                     }
                     Err(_) => {
-                        return Err(PiError::invalid_session_file(
-                            path.to_path_buf(),
-                            format!("line {line_no}: {parse_err}"),
-                        ));
+                        eprintln!(
+                            "warning: skipping unparseable line at {}:{} (truncated write?): {parse_err}",
+                            path.display(),
+                            line_no
+                        );
+                        continue;
                     }
                 }
             }
@@ -837,6 +839,53 @@ mod tests {
         let ids: Vec<&str> = s.message_entries().map(|(b, _)| b.id.as_str()).collect();
         assert_eq!(ids, vec!["a", "b"]);
     }
+
+    #[test]
+    fn truncated_final_line_is_skipped_with_warning() {
+        let tmp = TempDir::new().unwrap();
+        let path = tmp.path().join("s.jsonl");
+        // valid header + one valid entry + a truncated JSON fragment
+        let content = format!(
+            "{}\n{}\n{{\"type\":\"mess",
+            header_line("sess-1"),
+            msg_line("a", None, "2026-04-16T00:00:01Z", "hi")
+        );
+        fs::write(&path, content).unwrap();
+        let session = read_session_from_file(&path).unwrap();
+        // Header + 1 message; truncated line skipped
+        assert_eq!(session.entries.len(), 2);
+    }
+
+    #[test]
+    fn garbage_mid_file_line_is_skipped_and_later_entries_survive() {
+        let tmp = TempDir::new().unwrap();
+        let path = tmp.path().join("s.jsonl");
+        write_jsonl(
+            &path,
+            &[
+                &header_line("sess-1"),
+                "not json at all",
+                &msg_line("a", None, "2026-04-16T00:00:01Z", "hi"),
+            ],
+        );
+        let session = read_session_from_file(&path).unwrap();
+        // Header + 1 message; garbage line skipped
+        assert_eq!(session.entries.len(), 2);
+    }
+
+    #[test]
+    fn malformed_header_still_hard_fails() {
+        let tmp = TempDir::new().unwrap();
+        let path = tmp.path().join("s.jsonl");
+        // first non-empty line is invalid JSON -> Err (unchanged behavior)
+        fs::write(&path, "not json at all").unwrap();
+        let err = read_session_from_file(&path).unwrap_err();
+        // Should be an InvalidSessionFile or MalformedHeader error
+        assert!(matches!(
+            err,
+            PiError::InvalidSessionFile { .. } | PiError::MalformedHeader(_)
+        ));
+    }
 }
 
 // Small fallback helper for tests to set mtimes without adding a new dep.

site/_data/crates.json

@@ -65,7 +65,7 @@
   },
   {
     "name": "toolpath-pi",
-    "version": "0.6.0",
+    "version": "0.6.1",
     "description": "Derive Toolpath provenance documents from Pi (pi.dev) agent session logs",
     "docs": "https://docs.rs/toolpath-pi",
     "crate": "https://crates.io/crates/toolpath-pi",