# Infinite Sandbox 0.0.13a_03 release record

## Scope

Version 0.0.13a_03 hardens desktop placement and replaces visibly stepped local
water and lava presentation with continuous-looking render surfaces. It keeps
the animated water texture, reduced-order fluid safeguards, and removed N-key
new-world shortcut. New worlds remain available from the Escape menu and the
existing mobile New control.

This release is an experimental educational simulation. It is not certified,
validated for professional engineering work, or suitable for real-world safety
decisions.

## Placement input

- Left mouse press/release breaks terrain and right mouse press/release places
  the selected material.
- Mouse editing now uses pointer events with a stable per-gesture identifier,
  so release is handled when pointer lock or the canvas boundary changes during
  a held edit.
- A right-click target is refreshed at release while pointer lock is active.
- If floating-point contact at a smooth triangle boundary blocks placement, the
  engine retries exactly one 1 cm edit cell along the surface normal.
- A compatibility mouse-up handler completes the gesture in embedded browsers
  that lose pointer-up while acquiring pointer lock.
- Window blur and pointer cancellation clear the active edit rather than
  leaving a stuck mouse action.
- Hold duration still grows the edit from the one-centimeter minimum.
- A real-browser playtest performs a right-click placement, verifies a
  successful placement result and increased dynamic-piece count, checks the
  textured fluid surface, and requires zero uncaught page errors.

## Water rendering

- Local water and the far-field ocean use deterministic procedural ripple
  texture data.
- Water and lava use a render-only 3×3 Gaussian depth filter that removes
  abrupt cell-to-cell height steps without changing conserved simulation state.
- Color and opacity are calculated per vertex with smooth shoreline
  interpolation.
- Explicit finite-difference vertex normals make fluid lighting continuous.
- Local water geometry includes repeatable UV coordinates, and the texture
  offset advances with render time.
- The texture is a visual presentation layer and is excluded from engineering
  equations and validation claims.

## Reduced-order fluid changes

The fluid model version is `bounded-shallow-fluid-3`. The nominal 20 Hz update
is subdivided using gravity-wave speed, local cell size, a target Courant number
of 0.45, and a documented 32-substep ceiling. The closed-grid acceptance tests
require conservative volume behavior and no mass-balance tolerance violations
for their tested cases.

Runtime diagnostics now include adaptive substep totals, maximum adaptive
substeps, CFL-limited steps, target exceedances, timestep backlog and loss,
maximum free-surface gradient, donor limiting, signed and absolute mass
residuals, a relative residual, boundary exchange, phase-change removal, dry
clamps, and non-finite states.

This is still a depth-averaged browser-scale approximation. It does not resolve
three-dimensional velocity, turbulence, entrained air, groundwater, sediment
transport, thermochemistry, or validated site-specific boundary conditions.

## Removed shortcut

The N key has no assigned game action in this release. This prevents accidental
world replacement during play. The six-stage generation overlay remains in use
when generation is deliberately selected from the Escape menu or mobile New
control.

## Verification

`npm run verify:release` runs the complete automated suite, builds the
production bundle, and performs the nested-path HTTP smoke test. The fluid
suite checks conservation, adaptive-CFL behavior, texture assignment and
animation, smooth monotonic shoreline alpha, interpolated vertex opacity,
normalized fluid normals, UV generation, wetting, burning, water/lava
interaction, mobility contrast, deterministic seeding, and serialization.

Passing these tests demonstrates only the covered software behavior. Physical
validation, calibration, convergence studies over intended-use cases,
independent qualified review, and an audited quality process remain unresolved.