feat: A2UI v0.9 protocol support — message parsing, surface rendering, 12-component catalog

[blove]

Summary

Implements A2UI v0.9 protocol support (Google's open standard for agent-driven interfaces).

• New @cacheplane/a2ui library — framework-agnostic A2UI v0.9 types, JSONL message parser, JSON Pointer utilities, and dynamic value resolution with template interpolation
• A2UI Surface Store — Angular signal-based state management for A2UI surfaces (create, update components, update data model, delete)
• 12-component default catalog — Text, Image, Icon, Divider, Row, Column, Card, List, Button, TextField, CheckBox, ChoicePicker matching the v0.9 basic catalog
• A2UI Surface Renderer — converts A2UI surfaces to json-render Specs, resolves data bindings, renders via existing <render-spec> pipeline
• ContentClassifier integration — ---a2ui_JSON--- prefix detection now routes to JSONL parser + surface store instead of the single-JSON parser
• ChatComponent template — auto-renders A2UI surfaces when detected in AI messages

Architecture

A2UI messages stream as JSONL → A2uiMessageParser splits lines and extracts typed envelopes → A2uiSurfaceStore maintains surface state (components + data model) → A2uiSurfaceComponent converts to json-render Spec with resolved data bindings → <render-spec> renders via the catalog's Angular components.

Test plan

• 33 @cacheplane/a2ui tests pass (pointer, parser, resolver)
• 10 surface store tests pass
• All chat lib tests pass including A2UI classifier integration
• Lint clean (added a2ui selector prefix to eslint config)
• Phase 2: actions, validation, two-way data binding, remaining components (Tabs, Modal, Video, etc.)

[vercel]

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Project	Deployment	Actions	Updated (UTC)
cacheplane	Ready	Preview, Comment	Apr 9, 2026 4:47pm