v0.9.0

A visualization-and-playground release: the mapping visualization gains a
first-class light mode that follows the VS Code colour theme live, the
published site gains a server-free "Try it Live!" browser playground with a
test-enforced zero-network privacy guarantee, and a UX polish pass tightens
both. Also fixes the CLI startup crash on Windows reported in the project's
first external bug report. No language or grammar changes.

Visualization light mode & VS Code theme integration (Feature 32)

• Light and dark are now first-class, equally-supported themes for the
  mapping visualization. Both palettes are defined exactly once in
  tooling/satsuma-viz/src/tokens.css; every previously hardcoded colour
  was tokenized.
• <satsuma-viz> gains a reflected theme: "light" | "dark" property
  (default "light"); :host([theme="dark"]) is the single switching
  mechanism. Edge layers now inherit the host palette instead of pinning
  their own injected copy of the stylesheet (which had kept arrows
  permanently light).
• VS Code panels follow the editor colour theme live. All four
  ColorThemeKind values map to a viz theme, the webview envelope carries
  theme instead of the lossy isDark boolean, and an open panel restyles
  itself on theme change without a reload.
• Viz harness light mode: chrome and syntax-highlight colours moved to
  CSS variables, a Light/Dark header toggle, and ?theme= →
  prefers-color-scheme → dark resolution. Fixed a latent server bug where
  the GET / redirect dropped the query string, making ?theme= /
  ?fixture= / ?mode= silent no-ops.
• Playwright theme coverage: computed-colour assertions in both themes
  plus a both-theme screenshot gallery.
• ADR-026 records the theme contract: the component owns rendering,
  consumers select the theme.

"Try it Live!" browser playground (Feature 33)

• The published site now ships a live editor playground at
  /playground/ ("Try it Live!" in the nav, with a home-page CTA): edit
  Satsuma source — or open a local .stm file — and watch the lineage
  visualization re-render as you type.
• The entire pipeline runs in the browser. The import resolver in
  @satsuma/viz-backend became isomorphic (WHATWG URLs instead of Node
  path/fs), the client builds models with the same
  buildModelResultFromSources as every other surface, and the harness's
  /api/model endpoint was retired after a client/server parity test.
• Zero-network privacy guarantee, enforced by tests. A dedicated
  Playwright project serves the static bundle under the GitHub Pages base
  path and fails if editing, opening, or saving a file issues a single
  network request. Source never leaves the browser.
• localStorage document library seeded from the bundled example corpus
  (edits never overwritten by re-seeding); cross-file import lineage
  resolves entirely in-browser.
• Editable, highlighted source pane: a zero-dependency overlay editor
  (transparent textarea over a coloured highlight layer) with debounced
  re-render; translucent selection keeps token colours visible.
• Collapsible source pane with real viz reflow — <satsuma-viz> gains
  a host ResizeObserver, so the visualization genuinely reclaims the width;
  the expanded pane takes half the window.
• Client-only Open and Save for local .stm files via
  <input type=file> + Blob download — no upload, no server.
• ADR-027 (browser-side viz pipeline) and ADR-028 (client-only
  document library) record the architecture.

Live editor UX polish (Feature 34)

• Detail view survives live edits: the selection re-binds by
  namespace + id across model rebuilds, expansion state is pruned rather
  than reset, and the view falls back to overview only when the mapping is
  actually gone.
• Edge anchors sit flush on cards: edge layers share the card layer's
  origin by construction, and header/pill geometry lives in a shared
  layout/geometry.ts so layout estimates and card CSS cannot drift apart
  (ADR-029).
• Metrics render as detail-view endpoints, with grain/slice/filter
  surfaced as pills, via a metric-adapter shared with the layout's port
  builder.
• Export SVG downloads a real, self-contained artifact — theme tokens
  are inlined at export time, which also fixes SVGs saved from the VS Code
  panel.
• Branded, accessible chrome: satsuma logo + wordmark in the header,
  keyboard-operable "Hide source" / "Show source" collapse handle,
  vertically stacked truncating meta pills, and self-hosted Lexend chrome
  typography (OFL licence committed) with zero cross-origin font requests
  (ADR-030).

Windows support fixes

• CLI startup crash on Windows fixed (gh-265 — the project's first
  external bug report). Command modules were dynamically imported by raw
  absolute path, which Node's ESM loader rejects on Windows (C: read as a
  URL scheme); a documented command-loader now wraps specifiers with
  pathToFileURL. This also restores every CLI-backed feature of the
  VS Code extension on Windows.
• LSP validate diagnostics now build canonical file:// URIs with
  pathToFileURL instead of hand-gluing "file://" + path, which produced
  malformed URIs on Windows so validate diagnostics never attached.
• Follow-up tracked to add a Windows job to the CI matrix (sl-vmqv).

Fixes

• Missing canonical fixture restored (sl-dknl):
  examples/contracts/buy-to-om-order.stm was referenced by Playwright
  tests but never committed, which made the entire 40-test firefox harness
  suite throw and silently not run on main.
• Compact-card expansion re-runs the overview layout so neighbours
  re-flow and edges re-route instead of being painted over.

Dependencies

• typescript-eslint 8.60.1 → 8.61.0; transitive brace-expansion
  5.0.5 → 5.0.6 (GHSA-jxxr-4gwj-5jf2).