prometeu-runtime/discussion/workflow/plans/PLN-0088-define-read-only-render-resource-boundary.md

id	ticket	title	status	created	ref_decisions	tags
PLN-0088	vm-render-parallel-execution-boundary	Define Read-Only Render Resource Boundary	done	2026-06-05	DEC-0031	runtime renderer resources cache banks

Briefing

DEC-0031 requires render packets to carry small owned data and stable resource IDs, while heavy banks/caches remain resident and read-only to render consumers.

Objective

Define and enforce the read-only resource boundary needed before any worker can safely read scene/glyph/cache data.

Dependencies

• Source decision: DEC-0031.
• PLN-0087 should clarify the packet consumer path before this plan finalizes worker-facing APIs.

Scope

• Identify every resource read during Game2D rendering.
• Classify data as packet-owned, resident read-only, or logical-core mutable preparation state.
• Add trait/API boundaries for render read access where missing.
• Document which types must be Send + Sync for a real threaded worker.

Non-Goals

• Do not make resource swaps transactional.
• Do not capture Arc<GlyphBank> or Arc<SceneBank> inside every submission.
• Do not implement background asset loading policy.

Execution Method

1. Trace Game2D render reads from packet to glyph bank, scene bank, viewport cache, and framebuffer helpers.
2. Create a short internal module-level contract for render resource access.
3. Add or refine read-only access traits for banks/cache without exposing mutable runtime state.
4. Add compile-time assertions or targeted tests for Send + Sync where a threaded worker will require them.
5. Keep resource identity in submissions as IDs/handles, not heavy ownership captures.

Acceptance Criteria

• Render consumer APIs can be described as packet-owned plus read-only resource access.
• No worker-facing API requires &mut Hardware, &mut Gfx, live FrameComposer, or mutable VM state.
• Shared read APIs that cross thread boundaries have explicit Send + Sync expectations.
• Existing synchronous renderer behavior remains unchanged.

Tests

• Compile-time trait assertions for read-only resource APIs where practical.
• Unit tests for read-only bank/cache access.
• Existing asset/scene rendering tests continue to pass.

Affected Artifacts

• crates/console/prometeu-hal
• crates/console/prometeu-system
• crates/console/prometeu-drivers
• Relevant renderer/resource tests.