feat: add custom theme support via component_config

[paddymul]

Summary

• Add ThemeConfig type (7 optional color/scheme properties) nested inside ComponentConfig — rides the existing pipeline with no new traitlets or sync wiring
• resolveColorScheme() is the single source of truth for light/dark resolution — respects colorScheme override or falls back to OS detection
• className is now additive to the auto-detected AG Grid theme class (no longer replaces it)
• CSS custom properties (--bk-accent-color, --bk-accent-hover-color, --bk-bg-color) scoped per-instance via inline style on the wrapper div
• Server /load endpoint accepts optional component_config and merges it into df_display_args

Usage

import buckaroo
w = buckaroo.BuckarooWidget(df, component_config={
    'theme': {
        'colorScheme': 'dark',
        'accentColor': '#ff6600',
        'accentHoverColor': '#cc5200',
        'backgroundColor': '#1a1a2e',
    }
})

Test plan

• uv run pytest tests/unit/test_theme_config.py -v — 4 Python config flow tests pass
• uv run pytest tests/unit/ -v — 574 existing tests pass, 0 regressions
• uv run pytest tests/unit/server/ -v — 13 server tests pass
• TS compiles clean (tsc --noEmit — only pre-existing FloatingTooltip errors)
• npx playwright test theme-custom — Storybook visual assertions
• npx playwright test theme-custom-server — Server integration assertions
• Manual: load themed stories in Storybook, verify colors

Closes #582

🤖 Generated with Claude Code

[github-actions]

📦 TestPyPI package published

pip install --index-strategy unsafe-best-match --index-url https://test.pypi.org/simple/ --extra-index-url https://pypi.org/simple/ buckaroo==0.12.12.dev22418216574

or with uv:

uv pip install --index-strategy unsafe-best-match --index-url https://test.pypi.org/simple/ --extra-index-url https://pypi.org/simple/ buckaroo==0.12.12.dev22418216574

MCP server for Claude Code

claude mcp add buckaroo-table -- uvx --from "buckaroo[mcp]==0.12.12.dev22418216574" --index-strategy unsafe-best-match --index-url https://test.pypi.org/simple/ --extra-index-url https://pypi.org/simple/ buckaroo-table

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Persist component_config in buckaroo dataflow state

LoadHandler.post only overlays component_config onto session.df_display_args here, but buckaroo interactions later rebuild df_display_args from session.dataflow in DataStreamHandler._handle_buckaroo_state_change (websocket_handler.py), which never receives this config. In server mode="buckaroo", theme/custom component settings from /load are therefore lost after the first state-changing action (for example changing cleaning/post-processing), so the new feature does not persist through normal usage.

Useful? React with 👍 / 👎.

[chatgpt-codex-connector]

Honor forced colorScheme when backgroundColor is omitted

This style injection only sets --bk-bg-color when themeConfig.backgroundColor is provided, so a config like { colorScheme: 'dark' } leaves no background variable and .theme-hanger falls back to the OS media-query defaults in CSS. As a result, forced light/dark mode can still show the opposite wrapper/empty-grid background unless callers also set backgroundColor, which breaks the expected behavior of colorScheme override by itself.

Useful? React with 👍 / 👎.

[paddymul]

@codex implement any code fixes you see necessary on this PR

[chatgpt-codex-connector]

Summary

• Added a shared merge_component_config(...) helper and used it in /load, so component_config merging is centralized and reusable instead of being one-off logic in LoadHandler.post. buckaroo/server/handlers.pyL41-L53 buckaroo/server/handlers.pyL292-L294
• Persisted component_config in session state and re-applied it after buckaroo dataflow state changes, which fixes the regression where theme/custom config disappeared after the first interaction in mode="buckaroo". buckaroo/server/session.pyL30-L39 buckaroo/server/websocket_handler.pyL83-L91
• Fixed forced color-scheme behavior in the React viewer by always setting --bk-bg-color, using either explicit theme.backgroundColor or a scheme-based fallback (#ffffff / #181D1F). packages/buckaroo-js-core/src/components/DFViewerParts/DFViewerInfinite.tsxL162-L173
• Added a websocket integration test that verifies component_config survives a buckaroo_state_change round-trip after loading with /load in buckaroo mode. tests/unit/server/test_server.pyL252-L295

Testing

• ⚠️ pytest tests/unit/server/test_server.py -q (failed in environment: missing pandas in non-uv interpreter).
• ⚠️ uv run pytest tests/unit/server/test_server.py -q (failed in environment: missing built frontend artifact buckaroo/static/widget.js).
• ✅ uv run python -m compileall buckaroo/server/handlers.py buckaroo/server/websocket_handler.py buckaroo/server/session.py
• ✅ npm --prefix packages/buckaroo-js-core run -s build:tsc
• ⚠️ Playwright screenshot attempt via browser tool to http://127.0.0.1:6006 failed with ERR_EMPTY_RESPONSE (Storybook server not running), so no screenshot artifact was produced.

Committed on the current branch (22ccd8a) and created a follow-up PR via make_pr.

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