fix(sanity): delete BOOTSTRAP.md instead of emptying it

OpenClaw injects the bootstrap preamble when BOOTSTRAP.md EXISTS,
regardless of whether it's empty. Writing empty content still triggers
the preamble.

Changes:
1. Added workspace_files 'delete: true' support to lib_agent.py
2. Changed sanity task to delete BOOTSTRAP.md instead of emptying it

This ensures no bootstrap preamble is injected for the sanity check.

Author: olearycrew

BENCHMARK_VERSION

@@ -1 +1 @@
-2.0.0-rc6
+2.0.0-rc7

scripts/lib_agent.py

@@ -437,6 +437,14 @@ def _remove_readonly(func, path, _):
         (workspace / fname).write_bytes(content)
 
     for file_spec in task.workspace_files:
+        # Support delete: true to remove a file (e.g., BOOTSTRAP.md for sanity check)
+        if file_spec.get("delete"):
+            dest = workspace / file_spec["path"]
+            if dest.exists():
+                dest.unlink()
+                logger.info("Deleted workspace file: %s", file_spec["path"])
+            continue
+
         if "content" in file_spec:
             dest = workspace / file_spec["path"]
             dest.parent.mkdir(parents=True, exist_ok=True)

tasks/task_sanity.md

@@ -6,7 +6,7 @@ grading_type: automated
 timeout_seconds: 60
 workspace_files:
   - path: BOOTSTRAP.md
-    content: ""
+    delete: true
 ---
 
 ## Prompt