fix: preserve duplicate-id tool calls

maintainer edit: remap duplicate tool_use/tool_call ids instead of dropping later calls, so Anthropic-compatible providers that reuse ids for distinct parallel tool calls keep all requested work while still sending unique ids.

tests/agent/test_runner_governance.py

@@ -7,7 +7,7 @@ from unittest.mock import AsyncMock, MagicMock, patch
 import pytest
 
 from nanobot.config.schema import AgentDefaults
-from nanobot.providers.base import LLMResponse, ToolCallRequest
+from nanobot.providers.base import LLMResponse
 
 _MAX_TOOL_RESULT_CHARS = AgentDefaults().max_tool_result_chars
 
@@ -184,7 +184,7 @@ async def test_backfill_missing_tool_results_inserts_error():
     assert backfilled[0]["name"] == "read_file"
 
 
-def test_dedupe_tool_calls_removes_duplicate_ids():
+def test_dedupe_tool_calls_remaps_duplicate_ids():
     from nanobot.agent.runner import AgentRunner
 
     messages = [
@@ -194,15 +194,14 @@ def test_dedupe_tool_calls_removes_duplicate_ids():
             "content": "",
             "tool_calls": [
                 {"id": "a", "type": "function", "function": {"name": "x", "arguments": "{}"}},
-                {"id": "b", "type": "function", "function": {"name": "y", "arguments": "{}"}},
-                # Duplicate of "b" — would trigger "tool_use ids must be unique".
-                {"id": "b", "type": "function", "function": {"name": "y", "arguments": "{}"}},
+                {"id": "b", "type": "function", "function": {"name": "y", "arguments": '{"path":"a.txt"}'}},
+                # Duplicate id with different arguments should be preserved, not dropped.
+                {"id": "b", "type": "function", "function": {"name": "y", "arguments": '{"path":"b.txt"}'}},
             ],
         },
         {"role": "tool", "tool_call_id": "a", "name": "x", "content": "ra"},
         {"role": "tool", "tool_call_id": "b", "name": "y", "content": "rb"},
-        # Duplicate result for "b".
-        {"role": "tool", "tool_call_id": "b", "name": "y", "content": "rb-dup"},
+        {"role": "tool", "tool_call_id": "b", "name": "y", "content": "rb-remapped"},
     ]
 
     cleaned = AgentRunner._dedupe_tool_calls(messages)
@@ -214,11 +213,13 @@ def test_dedupe_tool_calls_removes_duplicate_ids():
             "content": "",
             "tool_calls": [
                 {"id": "a", "type": "function", "function": {"name": "x", "arguments": "{}"}},
-                {"id": "b", "type": "function", "function": {"name": "y", "arguments": "{}"}},
+                {"id": "b", "type": "function", "function": {"name": "y", "arguments": '{"path":"a.txt"}'}},
+                {"id": "b__dedupe_2", "type": "function", "function": {"name": "y", "arguments": '{"path":"b.txt"}'}},
             ],
         },
         {"role": "tool", "tool_call_id": "a", "name": "x", "content": "ra"},
         {"role": "tool", "tool_call_id": "b", "name": "y", "content": "rb"},
+        {"role": "tool", "tool_call_id": "b__dedupe_2", "name": "y", "content": "rb-remapped"},
     ]
 
 

tests/providers/test_anthropic_tool_result.py

@@ -10,6 +10,8 @@ Also tests that bare dicts without a "type" field are coerced to text
 blocks, fixing Anthropic "content.0.type: Field required" rejections (#3993).
 """
 
+from types import SimpleNamespace
+
 from nanobot.providers.anthropic_provider import AnthropicProvider
 
 
@@ -132,3 +134,33 @@ def test_anthropic_sanitized_tool_ids_avoid_simple_collisions():
     ids = [block["id"] for block in blocks if block["type"] == "tool_use"]
     assert len(ids) == len(set(ids)) == 2
     assert all(all(ch.isalnum() or ch in "_-" for ch in tool_id) for tool_id in ids)
+
+
+def test_anthropic_parse_response_remaps_duplicate_tool_use_ids():
+    response = SimpleNamespace(
+        content=[
+            SimpleNamespace(
+                type="tool_use",
+                id="toolu_same",
+                name="read_file",
+                input={"path": "a.txt"},
+            ),
+            SimpleNamespace(
+                type="tool_use",
+                id="toolu_same",
+                name="read_file",
+                input={"path": "b.txt"},
+            ),
+        ],
+        stop_reason="tool_use",
+        usage=None,
+    )
+
+    result = AnthropicProvider._parse_response(response)
+
+    assert len(result.tool_calls) == 2
+    assert result.tool_calls[0].id == "toolu_same"
+    assert result.tool_calls[0].arguments == {"path": "a.txt"}
+    assert result.tool_calls[1].id != "toolu_same"
+    assert result.tool_calls[1].id.startswith("toolu_")
+    assert result.tool_calls[1].arguments == {"path": "b.txt"}