feat(seer): Convert structured LLMContext JSON to markdown for on_page_context

[Mihir-Mavalankar]

• When the frontend sends a structured LLMContextSnapshot as JSON in on_page_context (instead of the legacy ASCII DOM screenshot), the explorer chat endpoint now detects it and converts it to a readable markdown string before forwarding to Seer. Non-JSON on_page_context (the existing ASCII screenshot) passes through unchanged.
  + This is the backend half of the structured page context feature. The frontend counterpart (conditionally sending JSON instead of ASCII when organizations:context-engine-structured-page-context flag is on + dashboards page) will follow in a separate PR per the frontend/backend split deploy requirement.

• This won't do anything currently right cuz the this is always false - snapshot = json.loads(on_page_context)

  Follow-up PRs

  1. Frontend PR: Wire getLLMContext() into useSeerExplorer.tsx — when the feature flag is on and the user is on a dashboards page, send JSON.stringify(getLLMContext()) as on_page_context instead of the ASCII screenshot
  2. Widget/chart context nodes: Add registerLLMContext('widget', ...) and registerLLMContext('chart', ...) to dashboard widget and chart components so the snapshot tree has richer data (query config, filters, etc. — not
     raw timeseries data)

[cursor]

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[azulus]

I think the answer is probably no, but there's a question as to whether some sort of indentation might make sense here. It tends to break markdown, but AI probably won't care tbh. My concern is that a parent with N children may cause the LLMs to kind of lose context of hierarchy later if they're reliant on matching up # counts. This is probably a non-issue, but flagging

[Mihir-Mavalankar]

Yeah with increasing depth matching up # is probably not best. I'll try this out a biton the a dashboard pages and see. I'll add indents if there seem to be issues.