docs: Split unified renderer_guide.md into core_sdk_spec.md, framework_adapter_spec.md, and sdks_spec.md for v0.9.1 and v1.0

[jacobsimionato]

Description of Changes

This Pull Request restructures and splits the unified, single-file renderer_guide.md into three highly focused, modular specifications across both version v0.9.1 and v1.0 folders:

1. sdks_spec.md (Unified SDK Architecture): Focuses on the global ecosystem and layout:

   • Ecosystem Dependency Structure: Describes the modular three-tier layout (Core SDK $\leftarrow$ Inference SDK and Framework Adapters).
   • Library Responsibilities: Outlines the specific functional mandates for A2UI Core SDK, Inference SDK, and Framework Adapters.
   • Development & Conformance Process: Highlights the unified spec-driven blueprint process and conformance tests to safely port features across many languages.

2. core_sdk_spec.md (A2UI Core SDK Specification): Focuses strictly on programmatic, framework-agnostic data and state management:

   • Core SDK interfaces (ComponentApi, SurfaceModel, ComponentContext).
   • Prerequisites (Schema and Observable/Signal libraries).
   • Design principles (Add Pattern for Composition, Standard multi-cast Observer Pattern, Granular Reactivity).
   • Protocol models, JSON pointer scoped evaluation (relative pathing, cascade/bubble notifications), and MessageProcessor.
   • Core basic catalog APIs, Strongly-Typed catalogs, and string expression logic (formatString).

3. framework_adapter_spec.md (A2UI Framework Adapter Specification): Focuses on visual presentation, lifecycle mapping, and UI testing:

   • Rendering Data Flow: Describes the precise data-to-view pipeline in the context of client-side visual A2UI rendering.
   • Base adapter views (ComponentImplementation functional/stateful hooks, ComponentInstance, and Surface root views).
   • Component rendering strategies (direct vs binder-based vs automated dynamic language binders).
   • Lifecycle rules (lazy subscriptions, path stability, unmount disposal, and relative context propagation in templates).
   • Interactive validation (Checkable traits) and visual catalogue overrides.
   • Comprehensive layout architecture and integration test requirements for the standard reference Gallery App.

Additionally, the workspace navigation instructions in .agents/skills/a2ui-sdk-design/SKILL.md have been updated to map to the new files.

Rationale

By moving from a dual-layered layout to a strict three-tiered layout (Core, Inference, Framework Adapters), A2UI achieves:

• Clean Separation of Concerns: Decoupling high-level architecture narratives (sdks_spec.md) from concrete, programmatic state layers (core_sdk_spec.md) and platform-native UI renderers (framework_adapter_spec.md).
• Complete Decoupling: Facilitating the implementation of headless servers (generating/validating streams) and client devices (orchestrating local inference or rendering layouts) with zero unnecessary dependency leakage.
• Maintainability: Simplifying the codebase footprint for spec-driven developer agents and open-source contributors.

Testing/Running Instructions

Reviewers can verify the changes by doing the following:

1. File Verification: Confirm that the files core_sdk_spec.md, framework_adapter_spec.md, and sdks_spec.md exist under both specification/v0_9_1/docs/ and specification/v1_0/docs/, and that the legacy renderer_guide.md files have been correctly deleted.
2. Prettier Verification: Run Prettier formatting to ensure syntax and structure are aligned:

   ./scripts/fix_format.sh

3. Reference Verification: Inspect .agents/skills/a2ui-sdk-design/SKILL.md to confirm the navigation points correctly to the split specs.

[gemini-code-assist]

Code Review

This pull request introduces a major restructuring of the A2UI documentation by splitting the architecture into a 'Core SDK Specification' and a 'Framework Adapter Specification'. It updates the documentation to reflect these changes, including updated agent implementation guides and cross-references. The review comments identified several broken path references in the documentation that pointed to the wrong version directory (v0_9 instead of v0_9_1). These have been noted for correction.

[gemini-code-assist]

The path reference uses v0_9 instead of v0_9_1. Since this file is located under the specification/v0_9_1/ directory, all references to the specification paths in this section (including lines 517–520) should be updated to use v0_9_1 to ensure consistency and prevent broken links.

Suggested change

	- `specification/v0_9/docs/basic_catalog_implementation_guide.md` (for functional specs and spacing rules for when you get to the basic catalog)
	- specification/v0_9_1/docs/basic_catalog_implementation_guide.md (for functional specs and spacing rules for when you get to the basic catalog)

[gemini-code-assist]

The path reference uses v0_9 instead of v0_9_1. Since this specification is for version v0.9.1 and resides in the specification/v0_9_1/ directory, the path should be updated to point to v0_9_1.

Suggested change

	- `specification/v0_9/docs/basic_catalog_implementation_guide.md` (for rendering, typography, alignment, and spacing rules).
	- specification/v0_9_1/docs/basic_catalog_implementation_guide.md (for rendering, typography, alignment, and spacing rules).

[gemini-code-assist]

The path reference uses v0_9 instead of v0_9_1. Update the path to use v0_9_1 to match the correct directory structure for this version.

Suggested change

	- Load JSON samples from `specification/v0_9/json/catalogs/minimal/examples/`.
	- Load JSON samples from specification/v0_9_1/json/catalogs/minimal/examples/.

[gemini-code-assist]

The path reference uses v0_9 instead of v0_9_1. Update the path to use v0_9_1 to match the correct directory structure for this version.

Suggested change

	- Update the Gallery App to load samples from `specification/v0_9/json/catalogs/basic/examples/`.
	- Update the Gallery App to load samples from specification/v0_9_1/json/catalogs/basic/examples/.