Task 007: Interactive Brachistochrone Calculator

Status: DONE (session 2026-02-23)

Goal

Add an interactive WASM-powered brachistochrone calculator to the Episode 1 report page, allowing users to explore how distance, ship mass, and transfer time affect required acceleration and ΔV.

Depends on

• Task 002 (Rust orbital mechanics core)
• Task 003 (WASM bridge)
• Task 005 (report pipeline)
• Task 006 (Episode 1 analysis)

What was done

1. Added brachistochrone_accel, brachistochrone_dv, brachistochrone_max_distance to solar-line-core (4 tests)
2. Exported all 3 functions via WASM bridge (3 tests)
3. Created ts/src/calculator.js — browser module with WASM-first + JS fallback
4. Added renderCalculator() to templates with sliders, presets, result table, verdict badge
5. Fixed WASM copy path bug in build.ts (Codex-identified)
6. Added calculator.js copy step in build pipeline
7. 9 new TS template tests + 4 new WASM round-trip tests
8. Total: 52 Rust + 134 TS = 186 tests, all passing

Codex consultation

• Recommended WASM+JS dual path, separate JS file (Option B), and identified WASM copy path bug

Origin

• ideas/interactive_brachistochrone.md
• Task 006 follow-up (mass ambiguity exploration)