SCAL-336112: share one conversation fetch across replayed MCP frames

[mouryabalabhadra]

Summary

Replaying a stored conversation mounts every answer frame at once, and each AutoFrameRenderer resolved on its own. A conversation with N answers made N identical GET /conversation/v2/{id}/public calls, plus the N POST .../load/public calls it needs anyway.

Change

• The list step moves out of resolveAnswerSessionParams into fetchAnswerIds(), which never rejects and returns null on failure.
• getAnswerIds() keeps a module-level Map<conversationUrl, Promise<string[] | null>> of in-flight list requests only:
  • Frames from the same conversation that resolve together share one GET.
  • The entry is removed as soon as its request settles, whether it succeeded or failed. A failed response is never reused, and a frame mounted later always reads a fresh list. Nothing is cached long-term, so a stored list can't go stale.
• The load POST is never shared: it returns live session state with its own expiry, and each answer needs its own.
• Index miss. The answer list only grows as messages are appended, so a list too short for the requested index may predate the answer. The frame reads the list once more before failing. Frames that miss together share that second read.
• Key is the full conversation-service URL, so different conversations (and hosts) never share.

Compatibility

No API or behaviour change for host apps, apart from the extra list read on an index miss. developer-examples/mcp/python-react-agent-simple-ui works unchanged on ^1.52.1 and picks this up on the next release.

Testing

New cases in auto-frame-renderer.spec.ts:

• Two concurrent frames from one conversation → one list call, two load calls, both resolved.
• Frames from different conversations → separate list calls.
• A failed list is not reused by a later frame.
• A frame mounted after the batch settles reads a fresh list.
• A list too short for the index is read exactly once more. Two concurrent missing frames share that re-read and both resolve.

[gemini-code-assist]

Code Review

This pull request optimizes the replay of stored chats by sharing in-flight answer-id list requests across concurrent frames of the same conversation, preventing redundant API calls. It also adds comprehensive unit tests to verify this behavior under various scenarios. The review feedback correctly identifies JSDoc formatting issues in the newly added helper functions, specifically pointing out missing parameter and return tags and their canonical ordering according to the style guide.

[pkg-pr-new]

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npm i https://pkg.pr.new/@thoughtspot/visual-embed-sdk@693

commit: e6467cc