Integrate eguidev (egui automation) behind an opt-in feature

[frewsxcv]

Draft for review — wires cortesi/eguidev (an egui automation/testing framework: screenshots, widget-state inspection, input injection, Luau scripting over an embedded MCP server) into rgis's bevy_egui UI, behind an off-by-default eguidev feature (native only). Normal builds and the wasm/web build are unaffected.

What this does

Lets an agent/script drive the native app and assert on structured widget state (text, rects, layout) rather than pixels. Driving the running app with edev smoke:

$ edev smoke ab_verify.luau --verbose
LOG: "version value_text = 'rgis v0.1.0'"
LOG: "version rect = [8.0,701.5 .. 67.3,716.5]"
LOG: "scale   rect = [4.0,318.0 .. 104.0,340.0]"
LOG: "check_layout issues = 0"
[PASS]

How it's wired

• third_party/eguidev/ — vendored fork, patched to build against egui 0.33 (rgis's version; upstream needs 0.34). Four edits, visible in the diff: actions.rs (drop MouseWheel.phase), instrument.rs (intrinsic_size is a field in 0.33), tools/layout.rs (global_style()→style()), devmcp.rs (begin_frame/end_frame made pub).
• rgis-ui/src/eguidev_adapter.rs — the bevy_egui↔eguidev bridge: a PreUpdate raw_input_hook system (after(ProcessInput).before(BeginPass)), begin/end_frame systems bracketing EguiPrimaryContextPass, and that pass set to a single-threaded executor (eguidev uses a thread-local frame model).
• rgis-ui/src/dev_ui.rs — cfg-switching button/label/track wrappers: register widgets with eguidev ids when the feature is on, plain egui otherwise.
• Instrumentation demo — bottom status bar (app-version, edit-crs, crs/coords) and the map scale bar.
• rgis/src/lib.rs — window pinned to 1280×720 @ scale 1.0 under the feature (matches Playwright's coordinate space).
• .edev.toml — launch config for edev.

Try it

cargo build -p rgis --features eguidev
cargo build -p edev --manifest-path third_party/eguidev/Cargo.toml
third_party/eguidev/target/debug/edev smoke <script>.luau --verbose

Caveats (why it's a draft)

• Native ≠ wasm. eguidev's runtime is native-only, so this drives a native build of an app that ships as wasm. Real divergence observed: the scale bar anchors mid-window natively vs bottom in the browser — a layout bug Playwright caught did not reproduce here.
• Screenshots not wired. bevy_egui ignores ViewportCommand::Screenshot, so eguidev's screenshot() would hang; a Bevy capture→egui::Event::Screenshot bridge is not built. Verification uses structured queries.
• Instrumentation is per-widget opt-in — only the 5 demo widgets are wrapped.
• Bundles an unrelated wasm build fix (zstd-sys no_asm).

eguidev vs Playwright

• eguidev: structured, deterministic widget assertions (good for CI) — but high integration cost, per-widget instrumentation, native-proxy fidelity gap.
• Playwright (already working): zero integration, tests the real shipped wasm in-browser — but pixel/eyeball verification.

Recommendation: Playwright stays the pragmatic choice for verifying what ships; eguidev earns its keep only if you want widget-level CI assertions and accept the tradeoffs.