Three small changes that resolve pyright errors and sharpen the logic:
- Guard `self._context` with the codebase's "should never happen"
early-return pattern, so we don't blindly call `.get_messages()` on
None.
- Skip `LLMSpecificMessage` items in the iteration. They're opaque
provider-specific payloads with no `.get()`, and the surrounding
logic only applies to standard tool-result messages.
- Match `role == "tool"` explicitly. The previous truthy-only check
was working by accident — the `tool_call_id` filter further down
was effectively narrowing to tool messages, but the intent is
clearer when stated upfront.