build_tool_result_payload

Build the tool.result hook payload (schema documented in hooks).

tool_output is capped to HOOK_TOOL_OUTPUT_LIMIT here so both surfaces apply the identical cap regardless of where the raw output originates. When the cap fires the value ends with TOOL_OUTPUT_TRUNCATION_MARKER (counted within the cap, so the result never exceeds the limit) so a consumer can tell a capped result from a short one. tool_args is intentionally not truncated (see HOOK_TOOL_OUTPUT_LIMIT).