preserve research tools through artifact completion

HARNESS_VERSION

@@ -1 +1 @@
-0.20.17
+0.20.18

src/clean_agent_preview.py

@@ -56,7 +56,10 @@ NATIVE_ROUND_LIMIT = 64
 INTERACTIVE_TOOL_CALL_LIMIT = 18
 INTERACTIVE_BROWSER_TOOL_CALL_LIMIT = 30
 INTERACTIVE_ROUND_LIMIT = 8
-NATIVE_ARTIFACT_RESEARCH_LIMIT = 12
+# Multi-record research tasks routinely need several search/fetch/inspection
+# pairs before an artifact can be grounded. Preserve twelve calls for writing,
+# verification, and final recovery within the bounded 32-call native budget.
+NATIVE_ARTIFACT_RESEARCH_LIMIT = 20
 SAME_TARGET_WRITE_LIMIT = 3
 ARTIFACT_RESEARCH_TOOLS = frozenset({
     'web_search', 'web_fetch', 'private_browser', 'pdf_extract', 'youtube_tool',

tests/test_harness_version.py

@@ -8,7 +8,7 @@ ROOT = Path(__file__).resolve().parents[1]
 def test_original_harness_version_is_canonical_semver() -> None:
     version = (ROOT / "HARNESS_VERSION").read_text(encoding="utf-8").strip()
 
-    assert version == "0.20.17"
+    assert version == "0.20.18"
     assert re.fullmatch(r"\d+\.\d+\.\d+", version)