Hermes-agent

tests/agent/test_tool_guardrails.py

@@ -0,0 +1,258 @@
+"""Pure tool-call guardrail primitive tests."""
+
+import json
+
+from agent.tool_guardrails import (
+    ToolCallGuardrailConfig,
+    ToolCallGuardrailController,
+    ToolCallSignature,
+    canonical_tool_args,
+    classify_tool_failure,
+)
+
+
+def test_tool_call_signature_hashes_canonical_nested_unicode_args_without_exposing_raw_args():
+    args_a = {
+        "z": [{"β": "☤", "a": 1}],
+        "a": {"y": 2, "x": "secret-token-value"},
+    }
+    args_b = {
+        "a": {"x": "secret-token-value", "y": 2},
+        "z": [{"a": 1, "β": "☤"}],
+    }
+
+    assert canonical_tool_args(args_a) == canonical_tool_args(args_b)
+    sig_a = ToolCallSignature.from_call("web_search", args_a)
+    sig_b = ToolCallSignature.from_call("web_search", args_b)
+
+    assert sig_a == sig_b
+    assert len(sig_a.args_hash) == 64
+    metadata = sig_a.to_metadata()
+    assert metadata == {"tool_name": "web_search", "args_hash": sig_a.args_hash}
+    assert "secret-token-value" not in json.dumps(metadata)
+    assert "☤" not in json.dumps(metadata)
+
+
+def test_default_config_is_soft_warning_only_with_hard_stop_disabled():
+    cfg = ToolCallGuardrailConfig()
+
+    assert cfg.warnings_enabled is True
+    assert cfg.hard_stop_enabled is False
+    assert cfg.exact_failure_warn_after == 2
+    assert cfg.same_tool_failure_warn_after == 3
+    assert cfg.no_progress_warn_after == 2
+    assert cfg.exact_failure_block_after == 5
+    assert cfg.same_tool_failure_halt_after == 8
+    assert cfg.no_progress_block_after == 5
+
+
+def test_config_parses_nested_warn_and_hard_stop_thresholds():
+    cfg = ToolCallGuardrailConfig.from_mapping(
+        {
+            "warnings_enabled": False,
+            "hard_stop_enabled": True,
+            "warn_after": {
+                "exact_failure": 3,
+                "same_tool_failure": 4,
+                "idempotent_no_progress": 5,
+            },
+            "hard_stop_after": {
+                "exact_failure": 6,
+                "same_tool_failure": 7,
+                "idempotent_no_progress": 8,
+            },
+        }
+    )
+
+    assert cfg.warnings_enabled is False
+    assert cfg.hard_stop_enabled is True
+    assert cfg.exact_failure_warn_after == 3
+    assert cfg.same_tool_failure_warn_after == 4
+    assert cfg.no_progress_warn_after == 5
+    assert cfg.exact_failure_block_after == 6
+    assert cfg.same_tool_failure_halt_after == 7
+    assert cfg.no_progress_block_after == 8
+
+
+def test_default_repeated_identical_failed_call_warns_without_blocking():
+    controller = ToolCallGuardrailController()
+    args = {"query": "same"}
+
+    decisions = []
+    for _ in range(5):
+        assert controller.before_call("web_search", args).action == "allow"
+        decisions.append(
+            controller.after_call("web_search", args, '{"error":"boom"}', failed=True)
+        )
+
+    assert decisions[0].action == "allow"
+    assert [d.action for d in decisions[1:]] == ["warn", "warn", "warn", "warn"]
+    assert {d.code for d in decisions[1:]} == {"repeated_exact_failure_warning"}
+    assert controller.before_call("web_search", args).action == "allow"
+    assert controller.halt_decision is None
+
+
+def test_hard_stop_enabled_blocks_repeated_exact_failure_before_next_execution():
+    controller = ToolCallGuardrailController(
+        ToolCallGuardrailConfig(
+            hard_stop_enabled=True,
+            exact_failure_warn_after=2,
+            exact_failure_block_after=2,
+            same_tool_failure_halt_after=99,
+        )
+    )
+    args = {"query": "same"}
+
+    assert controller.before_call("web_search", args).action == "allow"
+    first = controller.after_call("web_search", args, '{"error":"boom"}', failed=True)
+    assert first.action == "allow"
+
+    assert controller.before_call("web_search", args).action == "allow"
+    second = controller.after_call("web_search", args, '{"error":"boom"}', failed=True)
+    assert second.action == "warn"
+    assert second.code == "repeated_exact_failure_warning"
+
+    blocked = controller.before_call("web_search", args)
+    assert blocked.action == "block"
+    assert blocked.code == "repeated_exact_failure_block"
+    assert blocked.count == 2
+
+
+def test_success_resets_exact_signature_failure_streak():
+    controller = ToolCallGuardrailController(
+        ToolCallGuardrailConfig(hard_stop_enabled=True, exact_failure_block_after=2, same_tool_failure_halt_after=99)
+    )
+    args = {"query": "same"}
+
+    controller.after_call("web_search", args, '{"error":"boom"}', failed=True)
+    controller.after_call("web_search", args, '{"ok":true}', failed=False)
+
+    assert controller.before_call("web_search", args).action == "allow"
+    controller.after_call("web_search", args, '{"error":"boom"}', failed=True)
+    assert controller.before_call("web_search", args).action == "allow"
+
+
+def test_file_mutation_lint_error_result_is_not_a_tool_failure():
+    write_result = json.dumps({
+        "bytes_written": 12,
+        "lint": {"status": "error", "output": "SyntaxError: invalid syntax"},
+    })
+    patch_result = json.dumps({
+        "success": True,
+        "diff": "--- a/tmp.py\n+++ b/tmp.py\n",
+        "lsp_diagnostics": "<diagnostics>ERROR [1:1] type mismatch</diagnostics>",
+    })
+
+    assert classify_tool_failure("write_file", write_result) == (False, "")
+    assert classify_tool_failure("patch", patch_result) == (False, "")
+
+
+def test_same_tool_varying_args_warns_by_default_without_halting():
+    controller = ToolCallGuardrailController(
+        ToolCallGuardrailConfig(same_tool_failure_warn_after=2, same_tool_failure_halt_after=3)
+    )
+
+    first = controller.after_call("terminal", {"command": "cmd-1"}, '{"exit_code":1}', failed=True)
+    second = controller.after_call("terminal", {"command": "cmd-2"}, '{"exit_code":1}', failed=True)
+    third = controller.after_call("terminal", {"command": "cmd-3"}, '{"exit_code":1}', failed=True)
+    fourth = controller.after_call("terminal", {"command": "cmd-4"}, '{"exit_code":1}', failed=True)
+
+    assert first.action == "allow"
+    assert [second.action, third.action, fourth.action] == ["warn", "warn", "warn"]
+    assert {second.code, third.code, fourth.code} == {"same_tool_failure_warning"}
+    assert "Do not switch to text-only replies" in second.message
+    assert "keep using tools" in second.message
+    assert "diagnose before retrying" in second.message
+    assert "different tool" in second.message
+    assert controller.halt_decision is None
+
+
+def test_hard_stop_enabled_halts_same_tool_varying_args_failure_streak():
+    controller = ToolCallGuardrailController(
+        ToolCallGuardrailConfig(
+            hard_stop_enabled=True,
+            exact_failure_block_after=99,
+            same_tool_failure_warn_after=2,
+            same_tool_failure_halt_after=3,
+        )
+    )
+
+    first = controller.after_call("terminal", {"command": "cmd-1"}, '{"exit_code":1}', failed=True)
+    assert first.action == "allow"
+    second = controller.after_call("terminal", {"command": "cmd-2"}, '{"exit_code":1}', failed=True)
+    assert second.action == "warn"
+    assert second.code == "same_tool_failure_warning"
+    third = controller.after_call("terminal", {"command": "cmd-3"}, '{"exit_code":1}', failed=True)
+    assert third.action == "halt"
+    assert third.code == "same_tool_failure_halt"
+    assert third.count == 3
+
+
+def test_idempotent_no_progress_repeated_result_warns_without_blocking_by_default():
+    controller = ToolCallGuardrailController(
+        ToolCallGuardrailConfig(no_progress_warn_after=2, no_progress_block_after=2)
+    )
+    args = {"path": "/tmp/same.txt"}
+    result = "same file contents"
+
+    for _ in range(4):
+        assert controller.before_call("read_file", args).action == "allow"
+        decision = controller.after_call("read_file", args, result, failed=False)
+
+    assert decision.action == "warn"
+    assert decision.code == "idempotent_no_progress_warning"
+    assert controller.before_call("read_file", args).action == "allow"
+    assert controller.halt_decision is None
+
+
+def test_hard_stop_enabled_blocks_idempotent_no_progress_future_repeat():
+    controller = ToolCallGuardrailController(
+        ToolCallGuardrailConfig(
+            hard_stop_enabled=True,
+            no_progress_warn_after=2,
+            no_progress_block_after=2,
+        )
+    )
+    args = {"path": "/tmp/same.txt"}
+    result = "same file contents"
+
+    assert controller.before_call("read_file", args).action == "allow"
+    assert controller.after_call("read_file", args, result, failed=False).action == "allow"
+    assert controller.before_call("read_file", args).action == "allow"
+    warn = controller.after_call("read_file", args, result, failed=False)
+    assert warn.action == "warn"
+    assert warn.code == "idempotent_no_progress_warning"
+
+    blocked = controller.before_call("read_file", args)
+    assert blocked.action == "block"
+    assert blocked.code == "idempotent_no_progress_block"
+
+
+def test_mutating_or_unknown_tools_are_not_blocked_for_repeated_identical_success_output_by_default():
+    controller = ToolCallGuardrailController(
+        ToolCallGuardrailConfig(no_progress_warn_after=2, no_progress_block_after=2)
+    )
+
+    for _ in range(3):
+        assert controller.before_call("write_file", {"path": "/tmp/x", "content": "x"}).action == "allow"
+        assert controller.after_call("write_file", {"path": "/tmp/x", "content": "x"}, "ok", failed=False).action == "allow"
+        assert controller.before_call("custom_tool", {"x": 1}).action == "allow"
+        assert controller.after_call("custom_tool", {"x": 1}, "ok", failed=False).action == "allow"
+
+
+def test_reset_for_turn_clears_bounded_guardrail_state():
+    controller = ToolCallGuardrailController(
+        ToolCallGuardrailConfig(hard_stop_enabled=True, exact_failure_block_after=2, no_progress_block_after=2)
+    )
+    controller.after_call("web_search", {"query": "same"}, '{"error":"boom"}', failed=True)
+    controller.after_call("web_search", {"query": "same"}, '{"error":"boom"}', failed=True)
+    controller.after_call("read_file", {"path": "/tmp/x"}, "same", failed=False)
+    controller.after_call("read_file", {"path": "/tmp/x"}, "same", failed=False)
+
+    assert controller.before_call("web_search", {"query": "same"}).action == "block"
+    assert controller.before_call("read_file", {"path": "/tmp/x"}).action == "block"
+
+    controller.reset_for_turn()
+
+    assert controller.before_call("web_search", {"query": "same"}).action == "allow"
+    assert controller.before_call("read_file", {"path": "/tmp/x"}).action == "allow"