docs: document worldgen biome pipeline

[MichaelFisher1997]

Summary

• Document the terrain height pipeline, including noise inputs, region controls, modifier order, peak compression, and river carving.
• Document multi-parameter biome selection, structural constraints, priority behavior, river overrides, and region role effects.
• Add contributor guidance for safely adding or tuning biomes and required worldgen verification/baselines.

Testing

• nix develop --command zig build test

Fixes #662

[github-actions]

📋 Summary

Fixes #662 — Worldgen Phase 4: document biome selection and terrain modifier pipeline.

This PR adds a single comprehensive documentation file (docs/worldgen-biomes-and-terrain.md) that explains the terrain height pipeline, multi-parameter biome selection, region roles, and provides contributor guidance for safely adding or tuning biomes. All acceptance criteria from issue #662 are satisfied: key files and data structures are named, the modifier order and biome scoring are explained, region role interactions are documented, and required tests/baselines are mentioned.

📌 Review Metadata

• Reviewed Commit SHA: 6e00f3fc46920598c4b6b390d3f18650d0c0d73f
• Reviewed PR: docs: document worldgen biome pipeline #680
• Linked Issue: Worldgen Phase 4: document biome selection and terrain modifier pipeline #662 — fully addressed. The document covers terrain shape inputs, modifier order, multi-parameter biome scoring with priority overrides, region role interactions, and safe biome addition guidance. All acceptance criteria are met.

🔴 Critical Issues (Must Fix - Blocks Merge)

None identified.

⚠️ High Priority Issues (Should Fix)

None identified.

💡 Medium Priority Issues (Nice to Fix)

None identified.

ℹ️ Low Priority Suggestions (Optional)

[LOW] docs/worldgen-biomes-and-terrain.md:91 - Minor naming imprecision
Confidence: High
Description: The document instructs contributors to "Add or confirm the BiomeId in modules/world-core/src/block.zig". The actual type defined in block.zig is Biome (pub const Biome = enum(u8)). BiomeId is an alias exported from modules/world-core/src/root.zig (pub const BiomeId = block.Biome). This could cause minor confusion for new contributors.
Impact: Contributors might search block.zig for BiomeId and not find it immediately.
Suggested Fix: Change the line to: "Add or confirm the Biome type (aliased as BiomeId) in modules/world-core/src/block.zig".

📊 SOLID Principles Score

Principle	Score	Notes
Single Responsibility	N/A	Documentation PR; no code changes
Open/Closed	N/A	Documentation PR; no code changes
Liskov Substitution	N/A	Documentation PR; no code changes
Interface Segregation	N/A	Documentation PR; no code changes
Dependency Inversion	N/A	Documentation PR; no code changes
Average	N/A	Documentation only

🎯 Final Assessment

Overall Confidence Score: 95%

Confidence Breakdown:

• Code Quality: N/A% (documentation only)
• Completeness: 95% (fulfills all issue Worldgen Phase 4: document biome selection and terrain modifier pipeline #662 requirements; minor naming note)
• Risk Level: 5% (documentation-only change, zero runtime risk)
• Test Coverage: N/A% (no code to test)

Merge Readiness:

• All critical issues resolved
• No security concerns
• Tests present and passing (not applicable for docs)
• Low-priority naming suggestion addressed (optional)

Verdict:

MERGE — Clean documentation PR that fully addresses issue #662. Accurate, well-structured, and ready to merge.

{
  "reviewed_sha": "6e00f3fc46920598c4b6b390d3f18650d0c0d73f",
  "critical_issues": 0,
  "high_priority_issues": 0,
  "medium_priority_issues": 0,
  "overall_confidence_score": 95,
  "recommendation": "MERGE"
}

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