core/tools: add per-turn guard requiring lineno read before edit_lineno

tests/test_tools/test_edit_lineno.py

@@ -2,13 +2,21 @@ from __future__ import annotations
 
 from pathlib import Path
 
+from plyngent.agent import reset_lineno_tracker
 from plyngent.tools.file import edit_lineno, read_file, write_file
 from tests.test_tools.helpers import call_sync
 
 
+def _read_lineno(path: str) -> str:
+    """Read file with line numbers so edit_lineno allows the edit."""
+    _ = reset_lineno_tracker()
+    return call_sync(read_file, path, with_lineno=True)
+
+
 def test_edit_lineno_replace_middle(workspace: object) -> None:
     del workspace
     _ = call_sync(write_file, "a.txt", "one\ntwo\nthree\nfour\n")
+    _ = _read_lineno("a.txt")
     out = call_sync(edit_lineno, "a.txt", 2, 3, "TWO\nTHREE\n")
     assert "replaced lines 2-3" in out
     assert call_sync(read_file, "a.txt") == "one\nTWO\nTHREE\nfour\n"
@@ -17,6 +25,7 @@ def test_edit_lineno_replace_middle(workspace: object) -> None:
 def test_edit_lineno_delete_range(workspace: object) -> None:
     del workspace
     _ = call_sync(write_file, "b.txt", "a\nb\nc\n")
+    _ = _read_lineno("b.txt")
     out = call_sync(edit_lineno, "b.txt", 2, 2, "")
     assert "replaced" in out
     assert call_sync(read_file, "b.txt") == "a\nc\n"
@@ -25,6 +34,7 @@ def test_edit_lineno_delete_range(workspace: object) -> None:
 def test_edit_lineno_append(workspace: object) -> None:
     assert isinstance(workspace, Path)
     _ = call_sync(write_file, "c.txt", "only\n")
+    _ = _read_lineno("c.txt")
     out = call_sync(edit_lineno, "c.txt", 2, 2, "more\n")
     assert "appended" in out
     assert call_sync(read_file, "c.txt") == "only\nmore\n"
@@ -33,5 +43,14 @@ def test_edit_lineno_append(workspace: object) -> None:
 def test_edit_lineno_invalid(workspace: object) -> None:
     del workspace
     _ = call_sync(write_file, "d.txt", "x\n")
+    _ = _read_lineno("d.txt")
     assert "start_line" in call_sync(edit_lineno, "d.txt", 0, 1, "y")
     assert "end_line" in call_sync(edit_lineno, "d.txt", 2, 1, "y")
+
+
+def test_edit_lineno_rejects_without_prior_lineno_read(workspace: object) -> None:
+    del workspace
+    _ = call_sync(write_file, "e.txt", "hello\nworld\n")
+    _ = reset_lineno_tracker()
+    out = call_sync(edit_lineno, "e.txt", 1, 1, "hi\n")
+    assert "read" in out and "with_lineno=true" in out