refactor(ai_client): migrate _anthropic_history call sites to provider_state.get_history('anthropic')

TIER-2 READ conductor/code_styleguides/error_handling.md before Phase 1 (anthropic migration).

Phase 1 of code_path_audit_phase_3_provider_state_20260624. 13 call sites in _send_anthropic (lines 1430-1575) migrated from the module-level _anthropic_history alias to a local capture history = provider_state.get_history('anthropic'). The local capture pattern is used (instead of repeated provider_state.get_history() calls) to minimize lock acquisitions and improve readability.

The migration preserves behavior: ProviderHistory is the same singleton that _anthropic_history aliased to, so the migration is a pure refactor. The lock acquisition pattern is unchanged (this function does not acquire _anthropic_history_lock; thread-safety comes from _send_anthropic being called per-thread).

Verified: 37 tests pass across test_provider_state_migration.py + 6 ai_client test files.

Conventions: 1-space indentation, CRLF preserved, no comments added.

src/ai_client.py

@@ -1427,16 +1427,17 @@ def _send_anthropic(
  try:
   _ensure_anthropic_client()
   mcp_client.configure(file_items or [], [base_dir])
+  history = provider_state.get_history("anthropic")
   stable_prompt = _get_combined_system_prompt()
   stable_blocks: list[Metadata] = [{"type": "text", "text": stable_prompt, "cache_control": {"type": "ephemeral"}}]
   context_text   = f"\n\n<context>\n{md_content}\n</context>"
   context_blocks = _build_chunked_context_blocks(context_text)
   system_blocks  = stable_blocks + context_blocks
-  if discussion_history and not _anthropic_history:
+  if discussion_history and not history:
    user_content: list[Metadata] = [{"type": "text", "text": f"[DISCUSSION HISTORY]\n\n{discussion_history}\n\n---\n\n{user_message}"}]
   else:
    user_content = [{"type": "text", "text": user_message}]
-  for msg in _anthropic_history:
+  for msg in history:
    if msg.get("role") == "user" and isinstance(msg.get("content"), list):
     modified = False
     for block in cast(List[dict[str, Any]], msg["content"]):
@@ -1446,10 +1447,10 @@ def _send_anthropic(
        block["content"] = t_content[:_history_trunc_limit] + "\n\n... [TRUNCATED BY SYSTEM TO SAVE TOKENS. Original output was too large.]"
        modified = True
     if modified: _invalidate_token_estimate(msg)
-  _strip_cache_controls(_anthropic_history)
-  _repair_anthropic_history(_anthropic_history)
-  _anthropic_history.append({"role": "user", "content": user_content})
-  _add_history_cache_breakpoint(_anthropic_history)
+  _strip_cache_controls(history)
+  _repair_anthropic_history(history)
+  history.append({"role": "user", "content": user_content})
+  _add_history_cache_breakpoint(history)
   all_text_parts: list[str] = []
   _cumulative_tool_bytes    = 0
   
@@ -1458,13 +1459,13 @@ def _send_anthropic(
   
   for round_idx in range(MAX_TOOL_ROUNDS + 2):
    response: Any = None
-   dropped       = _trim_anthropic_history(system_blocks, _anthropic_history)
+   dropped       = _trim_anthropic_history(system_blocks, history)
    if dropped > 0:
-    est_tokens = _estimate_prompt_tokens(system_blocks, _anthropic_history)
+    est_tokens = _estimate_prompt_tokens(system_blocks, history)
     _append_comms("OUT", "request", {
       "message": (
        f"[HISTORY TRIMMED: dropped {dropped} old messages to fit token budget. "
-       f"Estimated {est_tokens} tokens remaining. {len(_anthropic_history)} messages in history.]"
+       f"Estimated {est_tokens} tokens remaining. {len(history)} messages in history.]"
       ),
      })
    
@@ -1478,7 +1479,7 @@ def _send_anthropic(
      top_p       = _top_p,
      system      = cast(Iterable[anthropic.types.TextBlockParam], system_blocks),
      tools       = cast(Iterable[anthropic.types.ToolParam], _get_anthropic_tools()),
-     messages    = cast(Iterable[anthropic.types.MessageParam], _strip_private_keys(_anthropic_history)),
+     messages    = cast(Iterable[anthropic.types.MessageParam], _strip_private_keys(history)),
     ) as stream:
      for event in stream:
       if isinstance(event, anthropic.types.ContentBlockDeltaEvent) and event.delta.type == "text_delta":
@@ -1492,10 +1493,10 @@ def _send_anthropic(
      top_p       = _top_p,
      system      = cast(Iterable[anthropic.types.TextBlockParam], system_blocks),
      tools       = cast(Iterable[anthropic.types.ToolParam], _get_anthropic_tools()),
-     messages    = cast(Iterable[anthropic.types.MessageParam], _strip_private_keys(_anthropic_history)),
+     messages    = cast(Iterable[anthropic.types.MessageParam], _strip_private_keys(history)),
     )
    serialised_content = [_content_block_to_dict(b) for b in response.content]
-   _anthropic_history.append({
+   history.append({
      "role":    "assistant",
      "content": serialised_content,
     })
@@ -1571,7 +1572,7 @@ def _send_anthropic(
       "type": "text",
       "text": "SYSTEM WARNING: MAX TOOL ROUNDS REACHED. YOU MUST PROVIDE YOUR FINAL ANSWER NOW WITHOUT CALLING ANY MORE TOOLS."
      })
-   _anthropic_history.append({
+   history.append({
      "role":    "user",
      "content": tool_results,
     })