fix(hunt): a row's entry points are the ones in its file or a caller's file, not the whole repository's list

The DSPy arm over the second pool failed with LMInvalidRequestError on every change with more than two rows, at no
cost: `source.facts_for` attached every entry point of the product tree to every row, 8190 records and 1.5 MB per
row on apache/seatunnel (the first pool's arm lost 11 changes the same way on trigger.dev and shopper), and the
rendered prompt was refused. The screen table of the second pool weighed 814 MB for the same reason.

A row now carries the entry points declared in its own file or in a file that calls the function, which is what the
input has described all along ("in-repository entry points that reach the file"). `source.entry_point_count`
follows that definition.

Co-Authored-By: Claude Fable 5.1 <[email protected]>

tests/test_source.py

@@ -189,3 +189,19 @@ def test_generated_reason_names_build_output_only(tmp_path):
     assert source.generated_reason(tmp_path, "big.js") == "too_large"
     assert source.generated_reason(tmp_path, "app.js") is None
     assert source.generated_reason(tmp_path, "missing.js") is None
+
+
+def test_facts_keep_only_the_entry_points_in_the_file_or_a_caller_file(tmp_path):
+    from openultrasast.mapping import EntryPointRecord
+
+    (tmp_path / "app.py").write_text("def run(x):\n    return x\n")
+    (tmp_path / "web.py").write_text("from app import run\n\ndef view():\n    return run(1)\n")
+    (tmp_path / "far.py").write_text("def other():\n    return 2\n")
+
+    def entry(path):
+        return EntryPointRecord(path, 1, 2, None, path, "route", "public", "external", [], [], "test", "fixture")
+
+    entries = [entry("app.py"), entry("web.py"), entry("far.py")]
+    facts = source.facts_for(tmp_path, "app.py", 2, entry_points=entries, files=["app.py", "web.py", "far.py"])
+    assert facts.callers == (("web.py", 4),)
+    assert [e.path for e in facts.entry_points] == ["app.py", "web.py"]