Ported tests from old viz converters

[CLowbrow]

Some gaps:

lingua/payloads/import-cases/openai-responses-function-call-output-input.assertions.json
2:  "_migrationNote": "Diverges from app/ui/trace/converters/openai-response-converter.test.ts (function_call_output handling): the old converter test expected a tool message from input.function_call_output plus the assistant output, but lingua import_messages_from_spans currently imports only the assistant message for this fixture.",

lingua/payloads/import-cases/openai-responses-web-search.assertions.json
2:  "_migrationNote": "Diverges from app/ui/trace/converters/openai-response-converter.test.ts (Web search): the old converter normalized string input into a user message plus two assistant output messages (web_search call + answer). lingua import_messages_from_spans currently drops string input and imports only the two assistant-side messages.",

lingua/payloads/import-cases/pydantic-ai-wrapper-user-prompt.assertions.json
2:  "_migrationNote": "Diverges from app/ui/trace/converters/pydantic-ai-converter.test.ts (wrapper format with user_prompt): the old converter synthesized user+assistant messages from pydantic-ai wrapper fields (`user_prompt`, `response.parts`), but lingua import_messages_from_spans currently imports 0 messages for this raw wrapper shape.",

lingua/payloads/import-cases/openai-responses-image-attachments.assertions.json
2:  "_migrationNote": "Diverges from app/ui/trace/converters/openai-response-converter.test.ts (Image generation attachments): the converter normalized this OpenAI Responses payload to user+assistant messages, but lingua import_messages_from_spans currently imports 0 messages for this attachment-heavy shape.",

lingua/payloads/import-cases/openai-responses-reasoning-only-output.assertions.json
2:  "_migrationNote": "Diverges from app/ui/trace/converters/openai-response-converter.test.ts (reasoning-only output failure case): the old converter synthesized an assistant message with empty content plus reasoning blocks, but lingua import_messages_from_spans currently drops reasoning-only output and imports only the system and user messages.",

lingua/payloads/import-cases/openai-responses-reasoning-blocks.assertions.json
2:  "_migrationNote": "Diverges from app/ui/trace/converters/openai-response-converter.test.ts (Reasoning blocks): the old converter merged reasoning summaries into the following assistant message, while lingua import_messages_from_spans currently imports reasoning as a separate assistant message, resulting in 3 messages instead of 2.",

lingua/payloads/import-cases/adk-basic-input-output.assertions.json
2:  "_migrationNote": "Diverges from app/ui/trace/converters/adk-converter.test.ts (basic ADK input/output): the old converter normalized ADK/Gemini-shaped `contents/parts` + `content.parts` into user+assistant messages, but lingua import_messages_from_spans currently imports 0 messages for this ADK span shape.",

lingua/payloads/import-cases/mastra-legacy-tool-message.assertions.json
2:  "_migrationNote": "Diverges from app/ui/trace/converters/mastra-response-converter.test.ts (legacy tool messages with toolId): the old converter emitted user + tool + assistant, but lingua import_messages_from_spans currently imports only the nested user message from `input.messages` and drops the tool/toolId variant plus `{text}` output.",

lingua/payloads/import-cases/langchain-human-ai-basic.assertions.json
2:  "_migrationNote": "Diverges from app/ui/trace/converters/langchain-converter.test.ts (human/ai basic): the old converter normalized LangChain message wrappers (`type: human/ai`, nested `generations`) into user+assistant messages, but lingua import_messages_from_spans currently imports 0 messages for this raw LangChain shape.",

lingua/payloads/import-cases/mastra-tool-call-span.assertions.json
2:  "_migrationNote": "Diverges from app/ui/trace/converters/mastra-response-converter.test.ts (tool_call span): the old converter synthesized assistant tool-call + tool result messages from raw input/output objects and metadata, but lingua import_messages_from_spans currently imports 0 messages for this Mastra tool_call span shape.",

lingua/payloads/import-cases/ai-sdk-openai-responses-steps.assertions.json
2:  "_migrationNote": "Diverges from app/ui/trace/converters/ai-sdk-converter.test.ts (OpenAI Responses steps format): the old AI SDK converter normalized `prompt` + `steps.content` into user+assistant messages, but lingua import_messages_from_spans currently imports 0 messages for this AI SDK wrapper shape.",

lingua/payloads/import-cases/mastra-agent-run-object.assertions.json
2:  "_migrationNote": "Diverges from app/ui/trace/converters/mastra-response-converter.test.ts (agent_run span): the old converter synthesized an assistant message from `{text: ...}` output, but lingua import_messages_from_spans currently imports 0 messages for this object-shaped Mastra span.",

lingua/payloads/import-cases/ai-sdk-legacy-messages-output.assertions.json
2:  "_migrationNote": "Diverges from app/ui/trace/converters/ai-sdk-converter.test.ts (legacy AI SDK format): lingua imports the nested input `messages` array but currently drops the legacy output object (`content`/`text` fields), while the old converter normalized both user and assistant messages.",

lingua/payloads/import-cases/mastra-agent-run-parts-input.assertions.json
2:  "_migrationNote": "Diverges from app/ui/trace/converters/mastra-response-converter.test.ts (agent_run parts-based input): the old converter normalized `parts` input plus `{text}` output into user+assistant messages, but lingua import_messages_from_spans currently imports 0 messages for this Mastra-specific shape.",

lingua/payloads/import-cases/openai-responses-image-generation-call.assertions.json
2:  "_migrationNote": "Diverges from app/ui/trace/converters/openai-response-converter.test.ts (Image generation): the old converter detected and normalized image_generation_call output to an assistant message, but lingua import_messages_from_spans currently imports 0 messages for this Responses shape.",

lingua/payloads/import-cases/mastra-llm-generation-tool-loop.assertions.json
2:  "_migrationNote": "Diverges from app/ui/trace/converters/mastra-response-converter.test.ts (llm_generation tool loop): lingua imports the nested `input.messages` conversation (including tool-call/tool-result content blocks) but drops the final assistant message synthesized by the old converter from the object-shaped `{text}` output.",

lingua/payloads/import-cases/openai-responses-real-world-tool-loop.assertions.json
2:  "_migrationNote": "Diverges from app/ui/trace/converters/openai-response-converter.test.ts (real-world OpenAI tool loop): the old converter produced 4 messages including assistant tool call + tool result, but lingua import_messages_from_spans currently imports only the user prompt and final assistant message for this Responses payload.",

lingua/payloads/import-cases/gemini-basic-generate-content.assertions.json
2:  "_migrationNote": "Diverges from app/ui/trace/converters/gemini-converter.test.ts (Gemini input without output): the old converter normalized Gemini `contents/parts` into a user chat message, but lingua import_messages_from_spans currently imports 0 messages for raw Gemini generateContent request shape.",

lingua/payloads/import-cases/openai-responses-mixed-output-order.assertions.json
2:  "_migrationNote": "Diverges from app/ui/trace/converters/openai-response-converter.test.ts (mixed output chronological order): the old converter produced 4 messages (user, assistant tool call, tool, user), but lingua import_messages_from_spans currently imports 0 messages for this OpenAI Responses output shape.",

lingua/payloads/import-cases/openai-responses-mixed-input-order.assertions.json
2:  "_migrationNote": "Diverges from app/ui/trace/converters/openai-response-converter.test.ts (mixed input chronological order): the old converter produced 4 messages (user, assistant tool call, tool, user), but lingua import_messages_from_spans currently imports 0 messages for this OpenAI Responses input shape.",