Implement deterministic scene contexts and headless rendering

[zoeyrose]

Important

This preserved product issue is now part of the fresh MIT replacement program. Final implementation owner: atrinik/renderer. Legacy C/SDL2, packet, global-state, and file-path details below are historical evidence only.

Replacement implementation contract

Create source-neutral complete scene contexts and offscreen output directly in the shared Rust renderer. The Go server exports bounded authorized full scene bundles separately from connection deltas; do not replay classic MAP packets as a durable format.

New implementation and tests are independent MIT work unless an exact contribution by an approved MIT provenance grantor is admitted through the recorded file-level MIT grant. Do not copy or mechanically translate other GPL source/tests. Preserve every player-facing, accessibility, disclosure, and performance design decision below.

Required verification

• Add deterministic Rust and/or Go tests at the owning boundary plus cross-language protocol fixtures for new fields.
• Exercise malformed/stale/reordered inputs and lifecycle failure without partial state.
• Use the shared renderer rather than a client/editor fork.
• Validate through a wrapper-managed replacement scenario where the feature is interactive.

Preserved product/design specification and historical implementation notes

Parent and roadmap

• Parent tracker: Generate world and region imagery through the shared renderer #13
• Roadmap: Roadmap: replace classic Atrinik with a fresh MIT Go and Rust stack atrinik#168
• Roadmap milestone: M2
• Prerequisites: Implement generated Game Protocol 1 transport and atomic session ingestion client#12, Migrate the legacy C client from SDL 1.2 compatibility APIs to SDL3 atrinik#128, Build the shared SDL3 and wgpu GPU renderer #17, Proposal: centralize deterministic server clocks, deadlines, and test time atrinik#155, Define stable ordered scene records, render roles, and tile admission server#19

Outcome

Create reusable server scene-capture and client renderer/resource contexts shared by the live client, offline renderer, and later editor preview.

Scope

• Separate complete scene capture from sockets, per-connection delta state, and mutable player assumptions.
• Separate map rendering from widget/process globals behind explicit scene, viewport, output-target, resource-provider, clock, lighting, fog, and cutaway inputs.
• Add isolated offline asset lookup for collected faces/animations/archetypes with strict missing-asset diagnostics.
• Support explicit deterministic world and player-view policies and clean repeated context lifecycle.

Superseded path / cleanup target

Delete proof-only adapters that duplicate the durable context. Do not copy map.c or create separate interactive/headless render implementations.

Acceptance criteria

• The connected client and atrinik-map-render call the same scene/render/resource modules.
• World and player-view manifests capture all inputs required for repeatability.
• Missing assets, malformed snapshots, and unsupported backends fail without partial output.
• Renderer and exporter contexts pass create/render/destroy/recreate tests without process-global leakage.

Validation baseline

Before: scene generation is coupled to socket deltas and rendering is coupled to client widgets/process globals.

After: transport-independent scene capture and reusable renderer contexts support deterministic offline consumers.

Run scene round trips, lifecycle/leak tests, equivalence fixtures, isolated-asset failures, and Linux/MinGW client/server builds.

This issue is a bounded child of #13. The parent remains open until every sibling child is complete.