fix: allocate unique browser challenge workspaces

examples/agent_challenges/browser_click_challenge/run_opencode_trials.py

@@ -132,11 +132,11 @@ def prepare_trial_workspace(
     source_root: Path = EXAMPLE_SOURCE_ROOT,
 ) -> TrialWorkspace:
     """Copy the authoring template into a clean ignored per-trial directory."""
-    root = workspaces_dir / f"{_safe_model_name(model)}-trial-{index:03d}"
-    if root.exists():
-        # Stale scratch files can leak answers between trials, so reset only
-        # the ignored per-trial directory before copying the template.
-        shutil.rmtree(root)
+    root = _next_trial_workspace_root(
+        workspaces_dir=workspaces_dir,
+        model=model,
+        index=index,
+    )
     shutil.copytree(template_dir, root)
     workspace = TrialWorkspace(
         root=root,
@@ -147,6 +147,24 @@ def prepare_trial_workspace(
     return workspace
 
 
+def _next_trial_workspace_root(
+    *,
+    workspaces_dir: Path,
+    model: str,
+    index: int,
+) -> Path:
+    stem = f"{_safe_model_name(model)}-trial-{index:03d}"
+    first = workspaces_dir / stem
+    if not first.exists():
+        return first
+    suffix = 2
+    while True:
+        candidate = workspaces_dir / f"{stem}-r{suffix:03d}"
+        if not candidate.exists():
+            return candidate
+        suffix += 1
+
+
 def write_trial_config(config_path: Path, *, source_root: Path) -> None:
     """Write a per-trial config with Python source path relative to config."""
     relative_source = Path(os.path.relpath(source_root, config_path.parent)).as_posix()

tests/examples/test_opencode_browser_click_challenge.py

@@ -286,7 +286,7 @@ def test_prepare_trial_workspace_copies_template_to_model_trial_dir(
     assert (prepared.root / ".gitignore").read_text(encoding="utf-8") == ".wf_store/\n"
 
 
-def test_prepare_trial_workspace_removes_stale_previous_attempt(
+def test_prepare_trial_workspace_uses_next_available_directory(
     tmp_path: Path,
 ) -> None:
     template = tmp_path / "template"
@@ -295,8 +295,9 @@ def test_prepare_trial_workspace_removes_stale_previous_attempt(
     source_root = tmp_path / "browser_click_workflow"
     source_root.mkdir()
     workspaces = tmp_path / "workspaces"
-    stale = workspaces / "opencode_mimo-v2.5-free-trial-001" / "old-answer.json"
-    stale.parent.mkdir(parents=True)
+    first = workspaces / "opencode_mimo-v2.5-free-trial-001"
+    stale = first / "old-answer.json"
+    first.mkdir(parents=True)
     stale.write_text("stale", encoding="utf-8")
 
     prepared = prepare_trial_workspace(
@@ -307,8 +308,9 @@ def test_prepare_trial_workspace_removes_stale_previous_attempt(
         source_root=source_root,
     )
 
+    assert prepared.root == workspaces / "opencode_mimo-v2.5-free-trial-001-r002"
     assert prepared.root.exists()
-    assert not stale.exists()
+    assert stale.read_text(encoding="utf-8") == "stale"
 
 
 def test_wf_command_prefix_for_config_uses_repo_relative_path() -> None: