Indoor accessibility, drawn from data.

A floor lists rooms as 2-D polygons in a flat coordinate frame, doors as points on shared walls, and a graph of nodes and edges that lives alongside the geometry. Edges carry feature tags like stairs, elevator, ramp, or narrow_passage so we can reweight them per-profile.

{
  "outline": [{ "x": 0, "y": 0 }, { "x": 100, "y": 0 }, ...],   // exterior boundary
  "walls":   [{ "id": "win-101", "kind": "window",
                "start": { "x": 8, "y": 50 }, "end": { "x": 22, "y": 50 } }],
  "rooms":   [{ "id": "room-101", "code": "101", "polygon": [...] }],
  "doors":   [{ "id": "d-101", "between": ["room-101", "corridor"], "position": {...} }],
  "nodes":   [{ "id": "n-elev", "roomId": "elevator-shaft", "features": ["elevator"],
                "connectsToFloor": { "floorSlug": "first", "nodeId": "n-elev" } }],
  "edges":   [{ "id": "e-c4-stair", "from": "c4", "to": "n-stair", "features": ["stairs"] }]
}

Schema source: src/lib/map/schema.ts, a Zod schema that validates the JSON and exports the matching TypeScript types.

• Outline, an optional polygon for the building's exterior boundary, drawn as a filled “floor base” with a thick stroke around its edges.
• Walls, line segments tagged exterior, interior, or window. Windows render as a cyan glass cut over the wall ink.
• Routes, drawn twice: once thick in the page background colour as a halo, once in the brand colour on top. That's the same trick Google Maps and Apple Maps use, and it keeps the line readable on top of any room fill.

• Heuristic: straight-line distance to the goal. Admissible because every edge cost is at least its straight-line length.
• Cost function: baseCost × max(profile.multiplier[feature]) over the edge's feature tags.
• Priority queue: a linear scan over the open set. Fine for teaching graphs and floor-plan-sized inputs; would be the first thing to swap in for a real deployment.

Source: src/lib/map/pathfind.ts, about 100 lines, with pathfind.test.ts next to it.

• Cross-floor edges inherit the source node's features. An n-elev ↔ n-elev link carries elevator, so the wheelchair profile applies the same slight surcharge it would on an in-floor elevator edge, and a stairs link is hard-blocked the same way.
• The result is a list of per-floor segments. The UI shows the current floor's segment with the route halo and offers a shortcut to switch to the next floor where the route continues.
• Heuristic is 0 (Dijkstra) since A*'s euclidean heuristic doesn't generalise across floors. Floor-plan-sized graphs are tiny, so this stays trivially fast.

Source: src/lib/map/multi-pathfind.ts, with multi-pathfind.test.ts covering the cross-floor cases.

• Map JSON in the system prompt, marked with cache_control: ephemeral. Turn 1 writes the cache; subsequent turns read it back at roughly a tenth of the price.
• Tool runner loop handled by the official SDK. The agent loop, tool execution, and tool-result plumbing are all in client.beta.messages.toolRunner().
• Captured route: when find_route succeeds, its node list is pushed back into the same highlightedRoute prop the manual route picker uses, so the visualisation is identical.

Source: src/lib/ai/assistant.ts, route handler at src/app/api/assistant/route.ts.

• Next.js 16 (App Router)

  Routing, layouts, server components.

• TypeScript + Zod

  Schema and types from one source.

• Tailwind v4 + shadcn/ui

  Design tokens compose into utility classes; primitives via Base UI.

• Inter + Geist Mono

  Body in Inter, code in Geist Mono. Both via next/font.

• next-themes

  Light, dark, and system theme, persisted to localStorage.

• Leaflet (CRS.Simple)

  Pan, pinch-zoom, mobile gestures over a flat coordinate frame.

• Prisma + SQLite

  Catalog of buildings and floors. Geometry stays in JSON.

• Anthropic SDK

  Adaptive thinking, betaZodTool tool runner, prompt caching.

• Vitest

  Pathfinder unit tests live next to the implementation.