Semiotic v3.7.1

Added

• Render evidence. renderChartWithEvidence() (semiotic/server) returns the SVG plus a
  machine-readable RenderEvidence object computed from the rendered scene graph — mark counts by
  scene type, resolved axis domains, an empty flag, category/node/edge counts, annotation count,
  and the accessible name — so agent repair loops and CI assertions can verify a chart actually drew
  data marks without pixel inspection. The MCP renderChart tool now returns the same evidence block
  alongside its SVG/PNG output.
• Misleading-design diagnostics. diagnoseConfig() gains a deception-check pack: inverted
  extents (INVERTED_AXIS), unlabeled dual-axis series (DUAL_AXIS_UNLABELED), trend windows
  cropped to a favorable slice (CHERRY_PICKED_WINDOW), negative values in part-to-whole encodings
  (PART_TO_WHOLE_NEGATIVE — an error for pie/donut/funnel), non-interpolating curve="basis"
  smoothing (NON_PASSING_CURVE), slope-distorting aspect ratios (EXTREME_ASPECT_RATIO), and
  over-sliced pies (PIE_TOO_MANY_SLICES). These patterns mislead human readers and — per the
  chart-deception literature — vision-language models the same way.
• Theme contrast conformance gate. Every shipped theme preset is now tested against WCAG-derived
  floors (4.5:1 for text/tooltip/annotation roles, 3:1 for the focus indicator), with sub-3:1 mark
  colors pinned in an exact-match known-exceptions ledger so palette regressions fail and
  improvements must shrink the ledger. The axe integration scan re-enables the color-contrast
  rule on the strength of the gate.
• Scorecard top-1 agreement. The capability quality scorecard now reports strict
  top1AgreementRate beside the lenient top-3 rate (current canonical set: 93% top-1 / 100% top-3),
  ranks the top-3 over distinct components rather than variants of one chart, and gains fixtures
  for the previously unexercised Heatmap, GaugeChart, FlowMap, and DistanceCartogram descriptors.
• ChatGPT Apps widget (experimental). The MCP server gains renderInteractiveChart, which
  renders a static-data chart through the same server render path as renderChart and returns a
  text/html;profile=mcp-app widget (ui://semiotic/chart-widget.html) with fit/zoom, data,
  hover, and render-evidence controls for ChatGPT developer-mode connectors over
  semiotic-mcp --http. A deployment playbook lives in the repo as CHATGPT_APPS_DEPLOYMENT.md,
  and an MCP protocol test suite covers the tool and widget resource end to end.
• Docs prerender route artifacts. The docs build now emits one prerendered HTML file per
  route with sanitized, route-specific machine-readable content in each page's <noscript>
  fallback, plus a docs/build/llms-routes.json route index for agent readers; the docs route
  check verifies the output.

Changed

• Theme legibility fixes (WCAG AA). pastels textSecondary/focus/annotation, bi-tool
textSecondary, and the tufte-dark/journalist/playful annotation colors were deepened to
  clear the contrast floors; the empty-state / BigNumber-empty / data-table-caption fallback color
  moved from #999 (2.8:1) to #666, matching the default theme's textSecondary.
• Capability descriptor judgment fixes. DifferenceChart no longer takes full compare-series
  marks when it would silently drop series beyond its native two; flat BarChart yields on crossed
  two-categorical matrices (Grouped/Stacked/Heatmap show the matrix) and on raw-observation data;
  ChoroplethMap requires at least two area features (a one-region choropleth has nothing to
  compare).
• contrastRatio() now parses 3-digit hex shorthand (#333), making the default themes measurable.

Tests

• Colocated tests for the NetworkCustomChart and OrdinalCustomChart escape hatches (the
  XY variant was already covered).