Iso 2.0 [9/12]: Gate, Troll-Bridge Walkable Logic + Quiz/Key Unlock

[putersdcat]

Spec reference

IsoRenderingPlanV2.1.md §5.2 Walkable Logic; §5.3 Gate/Quiz Integration

Goal

Feature tiles have walkability states:

• fence, stone-wall: walkable=never (blocks movement)
• gate: walkable=conditionally (locked=blocked, unlocked=passable)
• troll-bridge, bridge: walkable=always

Solver places gates at fence run openings. Quiz unlock changes gate state.
BFS pathfinder respects walkable map.

Technical requirements

• WalkableRule = { type: 'never' | 'always' | 'conditional', conditionFn?: () => boolean }
• walkableMap[row][col] = boolean (true = can enter)
• solver.placeGatesInFenceRuns() → inserts gate nano at calculated opening
• Gate locked state → walkable=false; unlocked → walkable=true
• Quiz trigger: player approaches gate → quiz UI opens → correct answer → unlocks

Acceptance criteria (ALL required to close)

• render_nano_tile gate straight-h → gate graphic clearly visible (locked appearance).
• render_nano_tile troll-bridge straight-h → bridge visible, spans negative-Z gap.
• render_nano_scene with fence perimeter + gate opening → gate at correct position in perimeter.
• In live demo: player cannot walk through locked gate, can walk through after quiz.
• BFS pathfind from inside to outside fence perimeter: path = null when gate locked, valid path when unlocked.
• PNGs committed: ProgressEvaluations/nano-gate-locked.png, scene-fence-with-gate.png, nano-troll-bridge.png.