Dependency roads: render the import graph as edges between buildings

[thalida]

Draw the repo's real dependency graph as roads/wires between buildings — so the streets aren't just directories, they're coupling. The "why is everything wired to that file" view.

Why it's compelling

Today streets = directory structure (where files live). Dependency edges show how files actually relate — the coupling graph, in 3D, over the city you already know.

What's already built (feasibility)

• Path/edge rendering exists: streets render as paths (app/src/city/components/streets/, streetPath, pathLine) — the machinery to draw a line between two world points (building A → building B) is largely there.
• Buildings have stable world positions post-layout, so an edge is just a curve between two building anchors.

The hard parts (design-first)

• Import parsing (backend, language-specific). Resolve each file's imports/requires to other files in the repo. Start with 1-2 ecosystems (e.g. JS/TS via import/require, Python via import) rather than all languages; unresolved/external imports are dropped. tree-sitter or lightweight regex per language.
• Graph scale. A large repo has huge edge counts — needs LOD / filtering (show edges only for the selected building, or only cross-directory edges, or a threshold). Drawing all edges at once will be noise + a perf hit (ties to Large-repo render hang: architectural perf pass (profile-first) #75).
• Rendering language. Arcs/wires over the city (glowing-rune / holographic vocabulary), directional (who imports whom), highlight on select. Avoid a hairball: default to "edges for the selected/hovered building" and make full-graph opt-in.
• New manifest data: a per-file dependency edge list → just gen-types + cache bump.

Phasing

1. Backend: import resolution for JS/TS (and/or Python) → per-file edge list in the manifest.
2. Frontend: on select/hover a building, draw its in/out dependency edges to other buildings.
3. Filters / LOD for a "show the whole graph" mode.

Exploration: prove the parse + single-building edges first; the full-graph view is where the design/perf work lives.