Add optional filter_mcp_tools() method to OperationValidatorExtension.
Called during tools/list after bank-level mcp_enabled_tools filtering.
Extensions can override to hide MCP tools per-user-per-bank based on
access policies. Default returns all tools unchanged.
- Add filter_mcp_tools to OperationValidatorExtension with default pass-through
- Wire into _get_enabled_tools in _apply_bank_tool_filtering
- Move _ALL_TOOLS to mcp_tools.py to avoid circular import (re-exported from mcp.py)
- Fail-open: if filter raises, log warning and return unfiltered tools
- Enforce ceiling: validator can narrow but never expand beyond bank config
- Add 8 tests: default, filtering, empty set, integration, composition,
can't-add-tools, exception fail-open, no-validator passthrough
f8285b7b90