Chart builder: drop unparseable expressions mid-edit, polite glyphed inline feedback

docs/chart-builder-enhancement-scope.md

@@ -25,7 +25,34 @@
 Newest first. The at-a-glance build-order tracker is §4; per-item detail is §3. This log is
 the quick "where are we" — read it first.
 
-- **2026-06-11** — **1C + 1D + 1E shipped (the Data section). Up next: Phase 2 (2A value-or-field channels, then 2B field shelf).**
+- **2026-06-11 (later)** — **Owed debts on the Data section closed. Up next: Phase 2 (2A value-or-field channels, then 2B field shelf).**
+  - **Council pass** on the new error/disclosure copy (the previously-deferred auto-fire
+    surface). Three a11y conformance gaps against `architecture/10` were fixed: the inline
+    expression feedback now carries a **status glyph** (round error / triangle warning), not
+    colour alone (§3, WCAG 1.4.1); the parse error is a **polite `role="status"`**, not a
+    per-keystroke assertive alert (APG Alert / WCAG 2.2.4); and the message is linked to its
+    input via **`aria-describedby`** (GOV.UK error-message). Unknown-field copy clarified to
+    "…— not a column in this dataset." Resolution recorded in `architecture/10` §5.
+  - **Manual/visual pass** run via a headless-Chrome (Playwright) walk-through of the live
+    builder — filter shelf (predicate + `is between`), field↔expression toggle, expression
+    error/unknown-field glyphs (filter _and_ calc inputs), calculated field, data-preview
+    table with type chips, smart-default chart. All surfaces render as intended.
+  - **Bug found + fixed (mid-edit preview resilience).** `filterTransformObject` /
+    `calculateTransformObject` emitted **any non-empty** expression — including a half-typed,
+    unparseable one — so the preview blanked with a raw render error while the user typed.
+    They now **drop a syntactically-invalid expression** like an empty/incomplete entry
+    (guarded by core `validateExpression`), matching `buildTransforms`' own "a config
+    mid-edit still renders" contract; the inline feedback still flags the typo. Pure core,
+    tested (+2 cases). Visually confirmed: an invalid filter/calc now keeps the last-good
+    chart instead of breaking the preview.
+  - **Verified:** `typecheck` + `test` (741 passing) + `eslint` clean.
+  - **Still open (copy judgment, user's call):** the preview's catch-all
+    `"Couldn't render this chart: {raw Vega message}"` puts a diagnostic in the headline
+    (arch 10 says diagnostics go in a disclosure) — correct in the editor, debatable in the
+    builder; and the builder's terse `"Dataset «X» not found."` drops the next-step the
+    contract mandates (near-unreachable in the builder). Both noted, not changed.
+
+- **2026-06-11** — **1C + 1D + 1E shipped (the Data section).**
   - A new **Data section** at the top of the builder's left pane — "here are your rows;
     shape them, then encode them" — emits the spec's top-level `transform` array.
   - **1C · Filters** — a guarded **field + operator + value** predicate shelf. Operators