diff --git a/soup_cli/experiment/tracker.py b/soup_cli/experiment/tracker.py
index 6f58a4c..1d075ca 100644
--- a/soup_cli/experiment/tracker.py
+++ b/soup_cli/experiment/tracker.py
@@ -80,9 +80,9 @@ def _get_db_path() -> Path:
 
 
 def generate_run_id() -> str:
-    """Generate a unique, sortable run ID: run_YYYYMMDD_HHMMSS_xxxx."""
+    """Generate a unique, sortable run ID: run_YYYYMMDD_HHMMSS_xxxxxxxx."""
     ts = datetime.now().strftime("%Y%m%d_%H%M%S")
-    suffix = secrets.token_hex(2)
+    suffix = secrets.token_hex(4)
     return f"run_{ts}_{suffix}"
 
 
diff --git a/tests/test_tracker.py b/tests/test_tracker.py
index 35c3ec0..d7371b4 100644
--- a/tests/test_tracker.py
+++ b/tests/test_tracker.py
@@ -18,9 +18,9 @@ def test_generate_run_id():
     """Run IDs should be unique and match expected format."""
     rid = generate_run_id()
     assert rid.startswith("run_")
-    # run_ (4) + YYYYMMDD (8) + _ (1) + HHMMSS (6) + _ (1) + xxxx (4) = 24
-    assert len(rid) == 24
-    # Uniqueness
+    # run_ (4) + YYYYMMDD (8) + _ (1) + HHMMSS (6) + _ (1) + xxxxxxxx (8) = 28
+    assert len(rid) == 28
+    # Uniqueness (8 hex chars = 4 billion possibilities, no collisions in 100)
     ids = {generate_run_id() for _ in range(100)}
     assert len(ids) == 100