Pathfinding Route Modes (Fastest vs Direct)

3.1 Source of truth

Sim already applies per-kind modifiers in TerrainKind::modifiers → (stamina_drain_mult, move_speed_mult). Pathfinding must not keep a separate hand-tuned cost table that drifts from those speeds.

Canonical Fastest cost (integer grid units):

cost(kind) = round(BASE / move_speed_mult(kind))

with BASE = grass baseline (today’s DEFAULT_COST 10), and impassable kinds (Rock, DeepWater) remaining non-walkable (u16::MAX / blocked).

Direct mode: every walkable cell uses BASE (uniform).

3.2 Feel without lying

Raising Road move_speed_mult makes the player actually faster on roads and makes Fastest prefer roads in proportion.

Corridor stickiness: when both path endpoints resolve to Road or Trail, Fastest multiplies off-path cell costs (×3) so A* stays on the pavement instead of cutting grassy corners. Direct is unchanged. Escape onto non-path still works if the corridor is blocked.

Building pads: nav blocking for buildings matches runtime collision (PLAYER_RADIUS only). Extra clearance must not seal road cells the player can still walk (that forced grass detours beside storage halls).

3.3 Admissible heuristic

A* octile h must scale by the minimum walkable Fastest cost (fastest terrain, e.g. Road) so paths stay optimal under variable costs.

4. API surface

pub enum PathMode {
    Fastest,
    Direct,
}

// find_path* / PathSession::plan / replan take PathMode
// AutoNavigator reads ClientConfig → PathMode

Call sites:

5. Client UX

• Field: ClientConfig.auto_nav_mode ("fastest" | "direct", default fastest)
• Settings: gfx Connection / play options (F2 or adjacent) — radio or toggle
• Optional later: keybind to flip mid-route and replan
• Changing mode while auto-nav is active → replan with the new mode
• Client version bump when shipping (client-path change)

No content editor / YAML surface — this is a client preference, not authored content.

7. Out of scope

• Per-NPC authored path mode overrides
• Stamina-minimizing routes (time-only for Fastest v1)
• Hierarchical / long-range road graphs beyond cell A*
• Native editor / content editor map tools for the toggle