> **STATUS (2026-06-23):** the top-level `set_main_loop(...,1)` `throw "unwind"` treated as current here **is gone** — replaced by the Asyncify **de-park** rAF pump (fatal under native wasm-EH; see [`../wasm-exceptions/09`](../wasm-exceptions/09-event-loop-deparking-plan.md)). The de-park regressed the coroutine suite, and **Design B is now being built to fix it** ([`12`](12-design-b-asyncify-implementation-plan.md) + [`13`](13-design-b-engineering-spec.md)). Read below as the pre-de-park analysis.
> The goal is **one universal mechanism**, not patches scattered around. This file classifies the
> candidate fixes by *root cause* so it's clear what is part of the one solution, what is
> subsumed, and what is genuinely separate.
## §1. The candidate levers, by root cause
| Lever | Root cause it addresses | Relationship to the universal fix |
|---|---|---|
| **Sync clipboard `IsSupported`** | A *separate* semantic/UX bug: a cheap predicate doing a 2 s permission-gated async read on the idle path. | **NOT needed for correctness.** A correct per-context authority makes the 2 s sleep *safe* even when overlapped. Keep it only as an independent UX/perf improvement, or drop it. |
| **Trampoline self-heal** (`try/finally` around `Fibers.trampoline`) | A *different register*, `Fibers.trampolineRunning`, getting stuck `true` after a mid-loop unwind. | **Subsumed.** A real authority must own the trampoline anyway; "always reset the guard" becomes one of its invariants, not a standalone bolt-on. |
| **De-park `main()`** (`simulate_infinite_loop=0` + suppress teardown) | The `throw "unwind"` abandoning Asyncify state outside any scheduler's control, plus the null-`IsModal` lifecycle crash. | **Orthogonal** to `currData`. Whether it's required is decided by one measurement (§2). If required, it is *part of* the universal design (the main loop becomes a normal scheduler participant), not a hack. |
| **Per-context `currData` authority** | The single global slot shared by overlapping suspensions. | **The core.** This is the one universal mechanism. |
### Why de-parking doesn't automatically fall out of the authority
The authority governs `currData` during *normal* unwind/rewind transitions. But
`simulate_infinite_loop=1` is a **`throw "unwind"`** (`pcbnew.js:11392`) — a JS exception that
**bypasses all asyncify bookkeeping, including the authority's.** Two orthogonal design axes:
- **D1 — how does `main()` avoid returning into destructive cleanup?** (throw, vs. de-park +
suppress cleanup)
- **D2 — how is `currData` managed across overlaps?** (single slot, vs. unified authority)
The authority is purely D2; the throw is purely D1. They don't subsume each other. You *can*
build the authority while keeping the throw — its safety then hinges entirely on §2.
## §2. The one measurement that sets the scope
> **Is `Asyncify.currData` clean (null, no context parked) at the instant `wxGUIEventLoop::DoRun()`
> executes the `throw "unwind"`?**
- **If yes** → the throw abandons nothing; the **per-context authority alone is the complete
universal solution.** No de-parking needed.
- **If no** (a startup coroutine or the main fiber is still parked at the throw) → the throw
orphans a live buffer *outside the authority's control*. Then the clean answer is to **remove
the throw** (de-park), so the authority never has to recover from an abnormal teardown. (The
alternative — "reconcile/reset `currData` at the next tick" — is exactly the kind of paper-over
we want to avoid.)
**The diagnostic (cheap, JS-only, no full rebuild):** add `console.log`s of
