docs(release): cover design agent and canvas perf in v0.8.2 notes

The notes stopped at the 2026-07-23 state and never described the design
agent at all, despite it carrying the largest share of the v0.8.2 work.
Add the multi-screen generation, geometry-repair, provider/skill, and
large-document canvas performance sections, plus the image-crop, stroke
ordering, right-rail, and Windows save changes landed since.

RELEASE_NOTES/v0.8.2.md

@@ -1,8 +1,9 @@
 # OpenPencil v0.8.2
 
 `v0.8.2` is a prerelease focused on higher-fidelity Figma and HTML imports,
-lower transient memory use, smoother large-document workflows, safer `.op`
-persistence, and backward-compatible schema evolution.
+multi-screen AI design generation, lower transient memory use, smoother
+large-document workflows, safer `.op` persistence, and backward-compatible
+schema evolution.
 
 This update expands both the data OpenPencil can preserve and the controls
 available for editing that data. It also separates expensive conversion and
@@ -32,6 +33,12 @@ still remain available.
   copy, or opened without modifying the file on disk.
 - HTML import accepts complete pages, multi-file projects, and ZIP packages
   with local resources, nested CSS imports, and common text encodings.
+- The design agent generates multi-screen apps: screen groups can run in
+  parallel, shared navigation is unified across screens, and app-mode screen
+  navigation is wired into the generated document.
+- Panning and zooming very large documents uses layer caching and
+  level-of-detail so gestures stay responsive instead of dropping to a few
+  frames per second.
 
 ## Figma Import Fidelity
 
@@ -146,6 +153,28 @@ still remain available.
   practical to reduce duplicated buffers, queue size, and peak transient
   allocations.
 
+## Canvas Performance on Large Documents
+
+- Pan and zoom on very large documents (tens of thousands of nodes viewed
+  zoomed out) are substantially smoother. Each change below was measured
+  against a live profiling session rather than inferred.
+- The SVG path cache is budgeted by bytes instead of entry count, so a working
+  set of many thousands of visible paths no longer re-parses its own contents
+  every frame.
+- Text below roughly three device pixels skips shaping and paints a
+  representative bar, and leaf content below sub-pixel size skips painting
+  entirely.
+- Shadows and blurs that would render below one pixel skip their save-layers,
+  avoiding render-pass breaks and forced command submits that were expensive on
+  GL-backed Metal.
+- Pan gestures blit a retained offscreen layer with in-place scroll strips and
+  an approximate scaled zoom. The layer survives across gestures, and the
+  gesture-end frame restores full quality progressively, one tile per frame.
+- The event loop places periodic wait deadlines on a fixed grid so elapsed
+  deadlines are not re-armed immediately, removing an idle timer spin.
+- `OP_SLOW_FRAME_LOG=1` prints frames over 32ms with blit, scroll, and build
+  attribution for diagnosing future regressions.
+
 ## `.op` Saving and Overwrite Safety
 
 - Desktop Save and Save As are serialized background jobs, preventing
@@ -227,12 +256,104 @@ still remain available.
   automation workflows. Remote fetches retain bounded reads and SSRF
   protections.
 
+## AI Design Agent
+
+### Multi-Screen App Generation
+
+- Screen groups can run genuinely in parallel under the parallel-agents
+  setting, with live progress, per-group replay on completion, and distinct
+  per-group agent identities. Sequential runs announce their setting too, so
+  the active mode is always visible.
+- Multi-screen plans give each screen group its own root frame placed beside
+  the previous one, instead of collapsing every subtask onto a single root.
+  Plans with zero or one screen label keep the previous single-root behavior,
+  and append mode stays single-root.
+- Generated multi-screen documents carry screen markers and `onTap` navigation,
+  so app-mode preview navigates between screens instead of degrading to one
+  scrolling page. The wiring pass is deterministic, idempotent, and additive
+  only.
+- Shared navigation bars are unified across sibling screens and injected into
+  screens whose name matches a reference tab, so a failed navigation subtask
+  can no longer leave a screen bare. Authored navigation is never removed.
+- Active tabs are retargeted per screen even when a model draws every screen's
+  navigation identically, and push-in detail screens (those with a header back
+  control) no longer receive an injected tab bar.
+- Tab labels match brand-prefixed screen names by whole tokens, so a screen
+  named like `Wander - Trips` binds its `Trips` tab.
+- Screens the skeleton committed but never filled are detected by shape, retried
+  through a dedicated fill budget that does not consume the general turn cap,
+  and reported honestly in the transcript, the run summary, and an `(unfilled)`
+  canvas label when they still come up empty.
+- Design routing reads a canvas signal, so a continuation request in a language
+  the ASCII keyword gate did not match still reaches the design loop when the
+  canvas already holds a mobile-width screen. Explicit overrides still win.
+
+### Design Quality and Geometry Repair
+
+- Geometry diagnostics detect cross-subtree text collisions, and loop completion
+  is gated on unresolved blockers rather than reported as done with known
+  defects outstanding.
+- A `fill_container` card that collapsed to a sliver beside a fixed-width
+  sibling in a horizontal rail is widened to the widest fixed reference, before
+  the overflow clip pass rather than after it. Evenly split and deliberately
+  mixed fixed rails are left untouched.
+- Mobile content and section rails are enforced and linted, including appended
+  subtrees and rail edge cases, and primary mobile screens are required to carry
+  navigation.
+- Badges, pills, avatars, status dots, and compact painted text capsules get the
+  corner radii the surrounding design already establishes, and mobile-app
+  guidance teaches that tappable CTAs carry a corner radius.
+- Decorative stack layers are exempt from the empty-shell blocker, which was
+  pushing models to stuff content into the back layers of a card deck, and a
+  transparent text-bearing front card gains a surface fill when a painted layer
+  bleeds through.
+- Nested card roles survive cleanup, near-full-bleed orphan cards are rescued,
+  rejected radial sections are recovered, status indicator dots are kept out of
+  stub cleanup, and clipped child strokes in fit-content rows are padded.
+- Logical text alignment values are accepted rather than rejected, and compact
+  status geometry is stabilized.
+
+### Providers, Models, and Skills
+
+- The Gemini CLI provider is retired. Antigravity and Grok Build are available
+  as agent providers and as MCP CLI integrations; the Google Gemini API provider
+  is unaffected.
+- Antigravity slug model IDs are discovered correctly, and model capability
+  tiers were updated (MiniMax M3, Claude Fable, and Kimi K3 are treated as
+  full-tier).
+- When a CLI connect or model-discovery probe times out, OpenPencil keeps the
+  captured output instead of discarding it, recognizes authentication prompts,
+  and shows an actionable hint — a first-run CLI blocked on browser OAuth no
+  longer reports only a generic timeout.
+- Skill prompts are no longer silently truncated: five skills that had drifted
+  past their injection budgets were compressed, the generation budget is the
+  intended full-tier value, and both truncation paths now warn instead of
+  tail-cutting quietly.
+- Skill names are unique across the registry, so lookup by name is no longer
+  order-dependent. The public `get_guidelines` topic key is unchanged.
+- Failed subtasks keep their full spec for single-shot retry, the salvage pass
+  retries at minimal complexity instead of repeating the full ladder,
+  rate-limit exhaustion is classified as non-retryable, rolled-back design
+  batches are marked as errors, and screens committed before a turn cap are
+  salvaged rather than discarded.
+- Aborted design validation terminates instead of continuing to run, and the
+  desktop design terminal preserves its progress output.
+
 ## Editing and Rendering
 
 - Component swaps, masks, layer/fill compositing, image tile scale, and page
   background color are configurable instead of being import-only metadata.
 - Fill-rule editing, per-corner radii, layer blur, and background blur now
   reach the shared scene and paint paths.
+- Image fills can be cropped interactively, with the crop preview and controls
+  in the property inspector, and image upload is wired through the file menu
+  and the fill editor.
+- Container strokes paint above their children on canvas and in SVG export,
+  matching the expected stacking instead of being covered by child content.
+- Editing a property refreshes the affected scenes, so canvas output no longer
+  lags behind inspector changes.
+- The right rail is hidden when nothing is selected instead of showing an empty
+  inspector.
 - Missing-font prompts and font-management surfaces are available across native
   and web hosts, with imported fonts invalidating affected layout scenes.
 - Native user fonts are persisted and rediscovered at startup; web user fonts
@@ -306,6 +427,8 @@ still remain available.
 
 - Windows desktop startup falls back safely when the preferred native OpenGL
   configuration cannot be wrapped by the renderer.
+- Windows save commits are serialized, avoiding overlapping publications on the
+  platform where the replace step is least forgiving.
 - Image search, image generation, Figma conversion, HTML conversion, and save
   sessions use bounded or cancellable background work instead of extending the
   input event path.
@@ -341,6 +464,9 @@ still remain available.
   the installed document in the main WASM runtime. Total browser-process peak
   memory still depends on the document, Worker, storage implementation, and
   browser, and the complete canonical document still enters the main runtime.
+- The Gemini CLI agent provider and its MCP CLI integration are removed.
+  Existing Gemini CLI connections no longer appear in Agent Settings; the Google
+  Gemini API provider is unaffected.
 - Account sign-in is intentionally unavailable in this prerelease.
 - The public web SDK remains read-only.
 - The retired TypeScript application workspace is not part of this release.