Inspector: multi-view data inspection with a per-table view picker

docs/architecture/05-rendering-theming-preview.md

@@ -42,26 +42,25 @@ above it is data; everything below it is a Vega `View` we own and must tear down
 
 ### The data inspector rides the boundary too
 
-The data inspector (the Live Preview and Chart Builder panel showing the chart's input
-vs. resolved rows — spec §04) reads runtime rows through the handle, never the raw view:
-`RenderHandle.inspectData()` returns the input + resolved tables (`{ input, resolved }`,
-or `null` when no chart is up), wrapping the view exactly like `toImageURL`. It works in
-two layers:
+The data inspector (the Live Preview and Chart Builder panel showing each drawn table's
+input vs. resolved rows — spec §04) reads runtime rows through the handle, never the raw
+view: `RenderHandle.inspectData()` returns the inspectable tables (`{ tables }`, or `null`
+when no chart is up), wrapping the view exactly like `toImageURL`. It works in two layers:
 
-- **Enumerate + pick (`view.getState` + `core/result-data`).** A compiled Vega dataflow
-  holds many named datasets; Vega-Lite names them by convention — `source_<n>` per parsed
-  source, `data_<n>` per transform stage. The pure `pickSourceDataset` / `pickResultDataset`
-  choose the **most-upstream source** (the input) and **most-downstream output** (what the
-  marks draw), skipping dataflow internals (`marks`, `root`, layout, selection `*_store`s).
-  A spec with no transforms resolves both to the same table. The picking is pure (in `core`,
-  unit-tested); only the enumeration touches the view.
-- **Read lazily.** `getState` serializes the datasets it lists, so it is **only called while
-  the panel is open** — a collapsed inspector costs nothing, which is why the panel reads on
-  demand rather than on every render.
-
-Limitation: one name per direction can't represent a multi-view spec (layer/concat/facet
-produce several `data_<n>`); the most-downstream/upstream ones are returned, and a full
-dataset selector is left as a future option.
+- **Enumerate from the compiled spec (`core/inspect-views`).** A composed spec draws
+  several tables; `inspectableViews` walks the compiled Vega spec — the marks tree's
+  `from.data` (what each mark draws) and `data[].source` (the lineage, the documented Vega
+  format) — to list, in document order, one entry per **distinct drawn table** with its
+  `resolved` (post-transform, what the marks draw) and `input` (most-upstream source) ends.
+  Enumerating by drawn table, not by authored view, is forced by Vega-Lite desugaring (a
+  `point: true` line compiles to two layers — a compiled table can't be traced back to one
+  authored view). Selection `*_store`s and `facet_domain*` layout tables aren't drawn, so
+  they fall out for free. The walk is pure (in `core`, unit-tested); the boundary reads each
+  table's rows via `view.data(name)`.
+- **Read lazily.** Reading serializes rows, so it happens **only while the panel is open** —
+  a collapsed inspector costs nothing, which is why the panel reads on demand rather than on
+  every render. (A multi-view spec yields several tables; the panel's `SelectControl` picker
+  chooses which to show — labels never expose Vega's compiler names, see arch 10.)
 
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