Alpha 0.3.12: canonical water, rivers, ocean fog

[ael-dev3]

Summary

This draft adds the Alpha 0.3.12 canonical water foundation on top of protected main at f23643c0d07e91847cadd5445a294d965ad76e1c.

• Preserves the exact 10,000-cell Genesis 001 land authority and derives a radius-65 ocean apron with 2,871 connected ocean cells.
• Groups all 409 canonical lake cells into 362 deterministic lake bodies.
• Adds exactly 12 one-cell-wide, disjoint rivers (two per sector), 456 unique river cells, 24–72-cell paths, coast-reaching mouths, and no movement/pathfinding rule changes.
• Freezes fixed-point coastal analysis, deterministic priority-flood/depression-fill parent DAG, flow accumulation, fixed-point river surface grades, body metadata, and layout digest e9753e5eff5c73f05ef802aedf22575acf8ccbb634192827172f4d1455167f05.
• Appends SpacetimeDB candidate refs 37–40: realm_water_layout_v1, realm_water_body_v1, realm_water_cell_v1, and realm_environment_v1.
• Adds admin-only, no-input seed/activate/inspect reducers. The artifact remains staged/inactive and fail-closed until explicitly reviewed and activated.
• Adds one shared environment epoch, fail-closed client projection validation, connected ocean/lake/river rendering, ocean fog/mist, downward boundary skirt, reduced-motion/static behavior, existing rAF scheduler reuse, and bounded High/Balanced/Reduced budgets.
• Caps ordinary strategic overview at radius 28 so the complete board and ocean boundary cannot be presented as a tiny tabletop.

Review / activation boundary

• Draft only; do not merge, seed, activate, publish, deploy, change DNS, or alter release truth from this PR.
• This branch is intentionally based on the current protected mainline. It must be reconciled with the reviewed gameplay/resource/forest stack and the PR Visual: add procedural biome grass and wind #55 environment work before merging.
• Existing tables, world rows, terrain semantics, passability, movement costs, resource sites, castles, forests, and gameplay reducers are additive/unchanged.

Verification

• pnpm test -- --reporter=dot — 183 files, 1,644 tests passed, including canonical-water and projection coverage.
• pnpm build — production Vite build, runtime asset checks, and production-dist exclusion checks passed.
• pnpm stdb:verify-bindings — pinned SpacetimeDB CLI 2.6.1 binding verification passed.
• tsc -p spacetimedb/tsconfig.json --noEmit and root tsc -b passed.
• Disposable loopback additive migration proof — passed against refs 0–40 on SpacetimeDB 2.6.1 (artifact SHA-256 69a341a0b895e4336b8b96eb059f76787d5b75999776e77a682e2f07957fa52); loopback-only, no production endpoint or release mutation.

Review focus

• Exact digest and source commit in docs/reference/terrain/2026-07-19-genesis-canonical-water/manifest.json.
• Deterministic exclusion/capacity policy, source/mouth separation, parent DAG, flow accumulation, monotonic surfaces, and fog buffer.
• Append-only schema order and generated bindings.
• Admin authorization, idempotency, partial/orphan/drift rejection, inactive fallback, renderer cleanup, reduced motion, and quality telemetry.

[ael-dev3]

Superseded by merged PR #72. Canonical Water was integrated with corrected hydrology-DAG routing, server/browser terrain parity, exact environment attestation, and separate fail-closed seed/activation controls.