test(M00): diagnose waterfall tile ownership

Work-Package: M00-QAR-TILE-OWNERSHIP-001
Agent: sindo-main-codex
Tests: strict five-point terrain probe, coordination and documentation gates
Fidelity: tile 30_49 ownership is healthy; exact ray miss classified as triangle seam

coordination/claims/M00-QAR-TILE-OWNERSHIP-001.md

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+# M00-QAR-TILE-OWNERSHIP-001 — Waterfall terrain tile ownership
+
+<!-- OPENWC_CLAIM:M00-QAR-TILE-OWNERSHIP-001:sindo-main-codex:2026-07-13 -->
+
+## Ownership
+
+- Target: M00
+- Program: QAR
+- Owner/Agent ID: sindo-main-codex
+- Branch: `work/sindo-main-codex/m00-waterfall-tile-ownership`
+- Lease expires UTC: 2026-07-13
+- Integrator: milestone integrator
+
+## Outcome
+
+Identify the runtime transition that prevents waterfall tile `30_49` from exposing a terrain mesh to the height probe.
+
+## Non-goals
+
+- Changing streaming budgets or terrain behavior.
+- Rebuilding caches or modifying extracted assets.
+- Adding a production terrain query service.
+
+## Paths
+
+- Exclusive: terrain probe runtime ownership diagnostics
+- Shared/hotspots: renderer baseline documentation
+- Generated/ignored: local probe reports and caches
+
+## Contracts and data
+
+- Public API/events: additive diagnostic JSON fields
+- Schema/format version: terrain report remains schema 1
+- Migration/compatibility: additive fields only
+- Consumers: M00 fidelity diagnosis
+
+## Dependencies
+
+- Requires: merged terrain-height probe and local cache inventory
+- Blocks: waterfall terrain ownership classification
+- External state: local extracted/cache data
+
+## Verification
+
+- Commands: isolated waterfall probe, coordination and documentation gates
+- Fixtures: checkpoint tile `30_49`
+- Fidelity evidence: runtime state correlated with build 12340 waterfall viewpoint
+- Performance budget: offline diagnostic
+
+## Documentation deliverables
+
+- Inline public API docs: diagnostic output fields
+- Module specification: verification/source map if behavior changes
+- Data-flow diagram: update ownership transition if needed
+- Sequence/state/dependency diagrams: document observed tile transition
+- Source map/status updates: baseline findings
+
+## Simplicity and naming
+
+- Important names introduced: `available`, `queued_index`, `loading`, `state_present`, `mesh_source`
+- Simplest considered solution: inspect existing loader registries read-only
+- Rejected complexity/abstractions: new tracing framework
+- Unavoidable complexity and justification: none
+- Measured optimization evidence: not applicable
+
+## Status
+
+- State: ready
+- Done: raw/cache inventory, isolated runtime state, mesh AABB/local probe and nearby sampling diagnosis
+- Next: integrator review; placement/composition remains the actual paired-camera gap
+- Blocked by:
+
+## Handoff
+
+- Commit: branch HEAD
+- Results: tile 30_49 ownership and meshes are healthy; exact ray misses a triangle seam/edge, while a 2-unit offset samples terrain at 113.872
+- Remaining risks: nearby estimate is diagnostic and must not become a gameplay terrain-query contract
+- Documentation updated: `docs/RENDER_BASELINE.md`, `docs/modules/world-renderer.md`