perf(appkit-ui): enable tree-shaking with sideEffects flag and modular echarts imports

[MarioCadenas]

Problem (P-1, High)

@databricks/appkit-ui had no sideEffects declaration, so webpack/esbuild/Rollup consumers had to assume every module re-exported by the /react barrel (src/react/index.ts) is side-effectful and keep all of them. Importing just Button shipped the entire chart stack — including the full echarts bundle (~350KB gz), @tanstack/react-table, and marked + dompurify — because charts/base.tsx imported echarts-for-react's default entry, which imports the monolithic echarts package.

Changes

"sideEffects": ["**/*.css"] in packages/appkit-ui/package.json

This tells bundlers that only CSS files have import side effects, so any JS module whose exports are unused can be dropped from the graph. Reasoning for the array (vs false):

• No JS module in the package relies on import-time side effects from another module (no polyfills, no cross-module registration) — verified by survey. The new ECharts registration lives in the same module as BaseChart, so it always executes when any chart component is used.
• The package ships dist/styles.css (exported as ./styles.css), which consumers import purely for its side effect. Declaring false would let bundlers prune that import; ["**/*.css"] keeps it safe.
• The dist publish tool (tools/dist-appkit.ts) spreads the whole package.json, so the field survives into the published package.

Modular ECharts imports in charts/base.tsx

Switched from echarts-for-react (full echarts entry) to echarts-for-react/lib/core + echarts/core, registering exactly what the option builders in options.ts use:

• Series: LineChart (line + area), BarChart (vertical + horizontal), PieChart (pie + donut), ScatterChart, HeatmapChart, RadarChart
• Components: TitleComponent (title), TooltipComponent, LegendComponent, GridComponent (grid/xAxis/yAxis), VisualMapComponent (heatmap color scale)
• Features: LegacyGridContainLabel — the cartesian option builder sets grid.containLabel: true, which in ECharts 6 is a separately registered feature (the full bundle auto-includes it; the mount tests caught its absence as a runtime warning)
• Renderer: CanvasRenderer (BaseChart always renders with renderer: "canvas")

Nothing in options.ts/normalize.ts uses dataZoom, toolbox, markLine, dataset, or other components, so they are intentionally not registered. The ECharts instance type stays a type-only import type { ECharts } from "echarts" (erased at compile time). Consumers passing custom options that need extra features can register them in their own app via echarts/core's use() — documented in a comment at the registration site.

New mount tests (charts/__tests__/base.test.tsx)

Existing chart tests only covered pure option/normalize functions and never exercised ECharts rendering. ECharts does not throw on a missing registration — it logs "Series X is used but not imported" and renders a blank chart. The new suite mounts BaseChart for every chart family (line, area, bar, horizontal bar, scatter, pie, donut, radar, heatmap with visualMap) under jsdom with a canvas stub and fails on any missing-registration error/warning.

Verification

• pnpm build — dist preserves module structure (unbundle mode); built dist/react/charts/base.js imports only echarts/core subpaths, no bare echarts value import anywhere in dist
• pnpm vitest run --project appkit-ui — 17 files, 320 tests passed (including 9 new mount tests)
• pnpm -r typecheck, pnpm check:fix, pnpm docs:build — clean

This pull request and its description were written by Isaac.

[github-actions]

📦 Bundle size report

Compared against bundle-size-baseline.json (main).

@databricks/appkit

npm tarball (packed): 658 KB (-4.2 KB) — gzipped download (dist + bin; excludes release-only docs/NOTICE).

dist	raw	gzip
JS (runtime)	686 KB (-2.9 KB)	240 KB (-1.3 KB)
Type declarations	268 KB (-323 B)	91 KB (-113 B)
Source maps	1.3 MB (-9.1 KB)	445 KB (-3.3 KB)
Other	11 KB	3.7 KB
Total	2.3 MB (-12 KB)	779 KB (-4.7 KB)

Per-entry composition (own code — deps external (as shipped))

Entry	Initial (gz)	Lazy (gz)	Total (gz)	node_modules (min)	Own code (min)
.	74 KB (-185 B)	2.5 KB	76 KB (-185 B)	external	243 KB (-576 B)
./beta	39 KB	231 B	39 KB	external	117 KB
./type-generator	18 KB (-161 B)	0 B	18 KB (-161 B)	external	53 KB (-449 B)

Chunks:

Entry	Chunk	Load	Size (gz)
.	index.js	initial	70 KB
.	utils.js	initial	4.0 KB
.	remote-tunnel-manager.js	lazy	2.5 KB
./beta	beta.js	initial	30 KB
./beta	databricks.js	initial	5.7 KB
./beta	service-context.js	initial	3.0 KB
./beta	client-options.js	initial	219 B
./beta	databricks.js	lazy	128 B
./beta	index.js	lazy	103 B
./type-generator	index.js	initial	18 KB

@databricks/appkit-ui

npm tarball (packed): 298 KB (+946 B) — gzipped download (dist + bin; excludes release-only docs/NOTICE).

dist	raw	gzip
JS (runtime)	354 KB (-8.8 KB)	117 KB (-2.9 KB)
Type declarations	204 KB (+517 B)	73 KB (+266 B)
Source maps	676 KB (+3.5 KB)	220 KB (+1.3 KB)
CSS	16 KB	3.3 KB
Total	1.2 MB (-4.8 KB)	413 KB (-1.3 KB)

Per-entry composition (consumer bundle — deps bundled, peerDeps external)

Entry	Initial (gz)	Lazy (gz)	Total (gz)	node_modules (min)	Own code (min)
./js	4.2 KB	49 KB	54 KB	208 KB	11 KB
./js/beta	20 B	0 B	20 B	0 B	0 B
./react	429 KB (-162 KB)	49 KB	477 KB (-162 KB)	1.3 MB (-495 KB)	166 KB (-305 B)
./react/beta	20 B	0 B	20 B	0 B	0 B

Chunks:

Entry	Chunk	Load	Size (gz)
./js	index.js	initial	4.1 KB
./js	chunk	initial	120 B
./js	apache-arrow	lazy	49 KB
./js/beta	beta.js	initial	20 B
./react	index.js	initial	427 KB
./react	tslib	initial	2.1 KB
./react	apache-arrow	lazy	49 KB
./react/beta	beta.js	initial	20 B