fix(export): node-budget the single-page graph render so it can't hang (REQ-201)

[avrabe]

Refs #468-adjacent (same dogfooding sweep). Companion to REQ-200 (#473).

What I found (dogfooding the real export)

On the rivet repo itself (~900 artifacts), rivet export --format html --single-page runs for minutes producing nothing (effectively a hang), while the multi-page export of the same project finishes in ~6s.

Root cause

render_section_graph (rivet-core/src/export.rs) lays out the entire link graph eagerly via etch::layout::layout(pg, …) with no node budget. etch's layout is super-linear, so ~900 nodes effectively hangs the single-page path.

The serve path already guards exactly this: rivet-cli/src/render/graph.rs caps at DEFAULT_NODE_BUDGET = 200 and renders a "Graph above node budget" page instead of laying out an oversized graph. The static export simply never got the same guard.

Fix

In render_section_graph, if node_count > 200, skip the layout and emit a short note —

Graph has N nodes, exceeding the 200-node static-render budget — view it interactively in the rivet serve dashboard.

— mirroring the serve guard. Small graphs render an SVG exactly as before.

before:  single-page export on rivet repo → minutes / no output
after:   single-page export on rivet repo → ~3s, budget note present

Test

export::tests::render_section_graph_over_budget_skips_layout builds a 250-node graph and asserts the output contains the budget note and no <svg> (the layout that hangs).

Verification

cargo test -p rivet-core --lib export::tests::render_section_graph_over_budget_skips_layout (pass) · cargo fmt --check clean · cargo clippy --all-targets -- -D warnings exit 0 · rivet validate PASS. Manually confirmed rivet export --format html --single-page on the rivet repo now completes in ~3s (was minutes/hang). Implements + Verifies REQ-201.

🤖 Generated with Claude Code

[github-actions]

📐 Rivet artifact delta

Change	Count
Added	1
Removed	0
Modified	0
Downstream impacted (depth ≤ 5)	0

Graph

graph LR
  REQ_201["REQ-201"]:::added
  classDef added fill:#d4edda,stroke:#28a745,color:#155724
  classDef removed fill:#f8d7da,stroke:#dc3545,color:#721c24
  classDef modified fill:#fff3cd,stroke:#ffc107,color:#856404
  classDef overflow fill:#e2e3e5,stroke:#6c757d,color:#495057,stroke-dasharray: 3 3

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Added

• REQ-201

📎 Full HTML dashboard attached as workflow artifact rivet-delta-pr-474 — download from the workflow run.

_{Posted by rivet-delta workflow. The graph shows only changed artifacts; open the HTML dashboard (above) for full context.}

[codecov]

Codecov Report

❌ Patch coverage is 95.65217% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
rivet-core/src/export.rs	95.65%	1 Missing ⚠️

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