Journey System Overview

Purpose: Explain the moving parts of a Dystrail run: how configs are layered, how determinism is enforced, and which data packs drive behavior.

Core architecture

One JourneyController simulates every day from mile 0 to the boss gate (default route length 2100.0 in boss::ROUTE_LEN_MILES).
Each day emits a DayRecord (kind: Travel, Partial, NonTravel) with miles already partial-adjusted and tagged.
Game mode → policy family mapping:
- Classic family (GameMode::Classic) — baseline Oregon Trail pacing.
- Deep family (GameMode::Deep) — same pacing bands, higher variance/quirks.
Strategy overlay: Balanced, Aggressive, Conservative, ResourceManager. The overlay only changes numbers; code paths stay uniform.

Seeds derive from HMAC-SHA256(master_seed, domain_tag) → 64-bit seeds (see journey::RngBundle).
Independent streams: rng_travel, rng_breakdown, rng_crossing, rng_encounter.
Atomic crossings: exactly one RNG draw per crossing event regardless of outcome branch, preventing seed drift.
Replay guarantee: same seed + same data packs = identical simulation trace (used by tester suites).

All policy and tuning data live in dystrail-web/static/assets/data/ and are bundled into the shipped WASM build.

Journey families: journey/classic.json, journey/deep.json.
Strategy overlays: journey/overlays/*.json (merged on top of family data per field).
Supporting packs:
- boss.json (distance required, weights, rounds, min/max chance, biases)
- crossings.json, camp.json, exec_orders.json, endgame.json
- pacing.json, personas.json, result.json, store.json, vehicle.json, weather.json, game.json

Effective config = family ⊕ overlay. Examples (Classic + Balanced overlay):

Victory miles: 2100 → 2400 (overlay).
Partial ratio: 0.50 → 0.51.
Travel base mpd: 14.6 → 15.6; clamp remains 10.0–22.0.
Wear base/fatigue: 0.07 / 0.08 → 0.073 / 0.245.
Breakdown base/beta: 0.01 / 0.10 → 0.015 / 0.185.
Crossing probs: pass/detour/terminal 0.72 / 0.16 / 0.12 → 0.66 / 0.24 / 0.10; bribe/permit tuning updated accordingly.