test: split embedding lane tests (#4389)

* test: split embedding lane tests

* test: preserve embedding focus selector after lane split

tests/run_focus.py

@@ -47,6 +47,12 @@ AREAS: tuple[str, ...] = (
     "uncategorized",
 )
 
+# Backward-compatible aggregate selectors for focused runs whose original
+# monolithic files were split into more specific taxonomy sub-areas.
+SUB_AREA_ALIASES: dict[str, tuple[str, ...]] = {
+    "embedding": ("embedding", "embedding_memory"),
+}
+
 
 def normalize_sub_area(value: str) -> str:
     """Normalize a CLI sub-area value and remove an optional ``sub_`` prefix."""
@@ -102,6 +108,13 @@ def sub_area_type(valid_sub_areas: frozenset[str]) -> Callable[[str], str]:
     return validate
 
 
+def _sub_area_marker_expression(sub_area: str) -> str:
+    """Build the marker expression for a sub-area, including narrow aliases."""
+    aliases = SUB_AREA_ALIASES.get(sub_area, (sub_area,))
+    markers = [f"sub_{alias}" for alias in aliases]
+    return " or ".join(markers)
+
+
 @dataclass(frozen=True)
 class FocusSelection:
     """A single focused-selection request, decoupled from argparse and pytest."""
@@ -143,7 +156,10 @@ def build_marker_expression(
     if area:
         parts.append(f"area_{area}")
     if sub_area:
-        parts.append(f"sub_{sub_area}")
+        sub_expression = _sub_area_marker_expression(sub_area)
+        if " or " in sub_expression:
+            sub_expression = f"({sub_expression})"
+        parts.append(sub_expression)
     if fast:
         parts.append("not slow")
     if not parts: