fix(agent): harden canonical tool call deduplication

run_agent.py

@@ -4879,19 +4879,28 @@ class AIAgent:
 
         Valid JSON arguments are canonicalized so equivalent objects do not
         evade deduplication merely because their keys or whitespace differ.
-        Malformed arguments retain their raw representation rather than being
-        repaired here. Only the first occurrence of each unique pair is kept.
+        Duplicate object keys use the parser's last-value-wins semantics,
+        matching downstream argument parsing. Malformed or excessively nested
+        arguments retain their raw representation rather than being repaired
+        here. Only the first occurrence of each unique pair is kept.
         Returns the original list if no duplicates were found.
         """
+        seen_raw: set = set()
         seen: set = set()
         unique: list = []
         for tc in tool_calls:
+            raw_key = (tc.function.name, tc.function.arguments)
+            if raw_key in seen_raw:
+                logger.warning("Removed duplicate tool call: %s", tc.function.name)
+                continue
+            seen_raw.add(raw_key)
+
             arguments = tc.function.arguments
             try:
                 arguments = json.dumps(
                     json.loads(arguments), separators=(",", ":"), sort_keys=True
                 )
-            except (TypeError, ValueError):
+            except (RecursionError, TypeError, ValueError):
                 pass
             key = (tc.function.name, arguments)
             if key not in seen:

tests/run_agent/test_agent_guardrails.py

@@ -7,6 +7,7 @@ Covers three static methods on AIAgent (inspired by PR #1321 — @alireza78a):
   - _uniquify_tool_call_ids()   — Phase 2c: duplicate-id repair (lossless pairing)
 """
 
+import json
 import types
 
 import pytest
@@ -212,6 +213,36 @@ class TestDeduplicateToolCalls:
 
         assert out == [first, distinct]
 
+    def test_recursion_error_uses_raw_string_for_deduplication(self, monkeypatch):
+        def raise_recursion_error(_arguments):
+            raise RecursionError("maximum recursion depth exceeded")
+
+        monkeypatch.setattr("run_agent.json.loads", raise_recursion_error)
+        first = make_tc("terminal", '{"command":"one"}')
+        duplicate = make_tc("terminal", '{"command":"one"}')
+
+        out = AIAgent._deduplicate_tool_calls([first, duplicate])
+
+        assert out == [first]
+
+    def test_byte_identical_duplicate_is_parsed_only_once(self, monkeypatch):
+        original_loads = json.loads
+        calls = 0
+
+        def track_loads(arguments):
+            nonlocal calls
+            calls += 1
+            return original_loads(arguments)
+
+        monkeypatch.setattr("run_agent.json.loads", track_loads)
+        first = make_tc("terminal", '{"command":"one"}')
+        duplicate = make_tc("terminal", '{"command":"one"}')
+
+        out = AIAgent._deduplicate_tool_calls([first, duplicate])
+
+        assert out == [first]
+        assert calls == 1
+