Update deps, fix workspace hotpatching, add crash recovery

[enomado]

Summary

• Update dependencies: egui/eframe 0.32 → 0.34.1, subsecond 0.7.0-rc.0 → 0.7.4
• Remove dioxus-devtools dependency (causes compile errors via dioxus-core); reimplement devserver connection with dioxus-cli-config + tungstenite + serde_json
• Fix workspace crate hotpatching — the original workspace_crate_ui was not actually updating on hotpatch
• Add crash recovery — panic in workspace code shows red error in UI instead of killing the app
• Comprehensive README with architecture docs

What was broken and why

1. eframe 0.34 API change

App::update() → App::ui(), CentralPanel::show() → show_inside(). Fixed by updating call sites.

2. dioxus-devtools pulls in dioxus-core which doesn't compile

Replaced with a direct WebSocket connection to dx devserver (~30 lines), using only dioxus-cli-config for endpoint discovery.

3. SIGSEGV on workspace hotpatch (Linux)

dx on Linux only exports main (--export-dynamic-symbol,main). The patch .so couldn't resolve egui/std monomorphizations from the main binary → invalid pointer → crash.

Fix: .cargo/config.toml with --export-dynamic to export all symbols.

4. Workspace crate text not updating after hotpatch

This was the hardest bug. Three layers:

1. subsecond::call inside workspace crate — ZST closure's call_it is not in the jump table diff → removed
2. HotFn::current(workspace_fn).call() doesn't work — after the first tip-crate patch, App::ui runs from the patch .so. Inside the .so, workspace_crate_ui resolves through .so's GOT giving a .so address, but the jump table maps original_binary_addr → new_addr. So HotFn::call_as_ptr gets the .so address, doesn't find it in the jump table, and calls the old version.

Solution: OnceLock captures the original fn pointer before any patch. call_workspace_ui() does a direct lookup in subsecond::get_jump_table().map with this original address.

Before patch:  workspace_fn as ptr  →  0x437f020 (binary)   → found in jump table ✓
After patch:   workspace_fn as ptr  →  0x7f3a...fb90 (.so)  → NOT in jump table ✗
With OnceLock:  saved original ptr   →  0x437f020 (binary)   → found in jump table ✓

How Bevy compares

Bevy's #[hot] macro generates HotFn::current(fn).call() per system — but they don't support workspace crates at all ("only patches the tip crate"). Our OnceLock + jump table approach is the first working solution for workspace hotpatching.

Tested scenarios

All verified working on Linux (x86_64):

• Tip crate changes (widgets, layouts, styles)
• Workspace crate changes
• Simultaneous tip + workspace changes
• Crash recovery (panic → red error label → fix code → hotpatch picks up fix)
• Adding new functions to workspace crate

Test plan

• dx serve --hot-patch starts and builds successfully
• Edit src/my_component.rs → changes appear in ~1s
• Edit workspace_crate/src/lib.rs → changes appear in ~1s
• Add panic!() to workspace crate → app shows red error, doesn't crash
• Fix the panic → next hotpatch recovers

🤖 Generated with Claude Code