chart_line: polyline through N data points (normalized to max),
optional dots at each vertex. Emits a `path` node with computed SVG
`d`="M x y L x y …" + N `ellipse` dots. fit_content width = values
× point_spacing.
chart_pie: N colored slices via ellipse `startAngle`/`sweepAngle`
arc support. NOT the "stacked full ellipses" anti-pattern — each
slice has a UNIQUE sweep range (sums to 360°). Supports donut cut-
out via `inner_radius_ratio`. Default 6-color palette rotates.
All-zero input throws (degenerate chart can't be drawn).
Wired across all three paths + elements.md decision-tree entries +
keyword map + examples. Both use layout=none (absolute positioning
for vertices / slices stacked at origin).
Tests:
- pen-mcp: 8 cases chart_line + 8 cases chart_pie (height math,
clamp bounds, custom colors, donut, error paths, id uniqueness)
- Parametric coverage auto-extended (+2 cases each in 9 files)
- Total delta: 2979 → 3027 passing (+48).
Closes#45 + #46; covers part of #50 (charts entries).
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