fixes

ai_client.py

@@ -417,13 +417,44 @@ def _strip_cache_controls(history: list[dict]):
                 if isinstance(block, dict):
                     block.pop("cache_control", None)
 
+def _repair_anthropic_history(history: list[dict]):
+    """
+    If history ends with an assistant message that contains tool_use blocks
+    without a following user tool_result message, append a synthetic tool_result
+    message so the history is valid before the next request.
+    """
+    if not history:
+        return
+    last = history[-1]
+    if last.get("role") != "assistant":
+        return
+    content = last.get("content", [])
+    # Find tool_use blocks (content may be a list of dicts or SDK objects)
+    tool_use_ids = []
+    for block in content:
+        if isinstance(block, dict):
+            if block.get("type") == "tool_use":
+                tool_use_ids.append(block["id"])
+        else:
+            # SDK object
+            if getattr(block, "type", None) == "tool_use":
+                tool_use_ids.append(block.id)
+    if not tool_use_ids:
+        return
+    # Append a synthetic tool_result for each dangling tool_use
+    history.append({
+        "role": "user",
+        "content": [
+            {
+                "type":        "tool_result",
+                "tool_use_id": tid,
+                "content":     "Tool call was not completed (session interrupted).",
+            }
+            for tid in tool_use_ids
+        ],
+    })
 
 def _send_anthropic(md_content: str, user_message: str, base_dir: str) -> str:
-    """
-    Send via Anthropic using chunked inline text.
-    Context is split into <=_ANTHROPIC_CHUNK_SIZE char blocks with
-    cache_control:ephemeral on the last block, then the user message is appended.
-    """
     try:
         _ensure_anthropic_client()
 
@@ -434,6 +465,7 @@ def _send_anthropic(md_content: str, user_message: str, base_dir: str) -> str:
         ]
 
         _strip_cache_controls(_anthropic_history)
+        _repair_anthropic_history(_anthropic_history)
         _anthropic_history.append({"role": "user", "content": user_content})
 
         n_chunks = len(context_blocks)
@@ -513,9 +545,25 @@ def _send_anthropic(md_content: str, user_message: str, base_dir: str) -> str:
                         "tool_use_id": block.id,
                         "content":     output,
                     })
+                elif block.type == "tool_use":
+                    # Unknown tool - return an error result so history stays valid
+                    tool_results.append({
+                        "type":        "tool_result",
+                        "tool_use_id": block.id,
+                        "content":     f"ERROR: unknown tool '{block.name}'",
+                    })
 
+            # Always append tool_results when stop_reason was tool_use,
+            # even if the list is somehow empty (shouldn't happen, but be safe)
             if not tool_results:
-                break
+                # Synthesise a result for every tool_use block to keep history valid
+                for block in response.content:
+                    if block.type == "tool_use":
+                        tool_results.append({
+                            "type":        "tool_result",
+                            "tool_use_id": block.id,
+                            "content":     "ERROR: tool could not be executed.",
+                        })
 
             _anthropic_history.append({
                 "role":    "user",