- New route GET /admin/pipeline/lineage/schema/<model> — returns JSON
with columns+types (from information_schema for serving models),
row count, upstream and downstream model lists. Validates model
against _DAG to prevent arbitrary table access.
- Precomputes _DOWNSTREAM map at import time from _DAG.
- Lineage template: replaces minimal edge-highlight JS with full UX —
hover triggers schema prefetch + floating tooltip (layer badge, top 4
columns, "+N more" note); click opens 320px slide-in panel showing
row count, full schema table, upstream/downstream dep lists.
Dep items in panel are clickable to navigate between models.
Schema responses are cached client-side to avoid repeat fetches.
Staging/foundation models show "schema in lakehouse.duckdb only".
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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