fix: avoid default session id collisions

Author: he-yufeng

.gitignore

@@ -15,3 +15,4 @@ venv/
 .DS_Store
 dist/
 .pytest_cache/
+.tmp/

corecoder/session.py

@@ -7,6 +7,7 @@
 import json
 import re
 import time
+import uuid
 from pathlib import Path
 
 SESSIONS_DIR = Path.home() / ".corecoder" / "sessions"
@@ -15,11 +16,15 @@
 
 def _normalize_session_id(session_id: str | None) -> str:
     if not session_id:
-        return f"session_{int(time.time())}"
+        return _new_session_id()
 
     name = session_id.strip().replace("\\", "/").split("/")[-1]
     name = _SAFE_SESSION_RE.sub("-", name).strip(".-_")
-    return name or f"session_{int(time.time())}"
+    return name or _new_session_id()
+
+
+def _new_session_id() -> str:
+    return f"session_{time.strftime('%Y%m%d_%H%M%S')}_{uuid.uuid4().hex[:8]}"
 
 
 def _session_path(session_id: str) -> Path:

tests/test_session.py

@@ -0,0 +1,19 @@
+from corecoder import session as session_module
+from corecoder.session import load_session, save_session
+
+
+def test_default_session_ids_do_not_collide(tmp_path, monkeypatch):
+    monkeypatch.setattr(session_module, "SESSIONS_DIR", tmp_path)
+
+    first_id = save_session([{"role": "user", "content": "first"}], "model-a")
+    second_id = save_session([{"role": "user", "content": "second"}], "model-b")
+
+    assert first_id != second_id
+    assert load_session(first_id) == (
+        [{"role": "user", "content": "first"}],
+        "model-a",
+    )
+    assert load_session(second_id) == (
+        [{"role": "user", "content": "second"}],
+        "model-b",
+    )