Phase F F4: bounce machinery deleted — strand pin holds through the removal

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Td4ujboGuAw26jvbDQzehj

docs/features/async/22-absorbing-libcontext.md

@@ -1161,6 +1161,31 @@ each deletion must flip its spec in the same commit (the
 `fiber-resume-park` red→green flip is the template). That is the next Phase F
 increment after the bounce removal.
 
+### F4 — the doc-19 mainstack bounce is GONE (2026-08-09)
+
+Deleted in one increment: the `DoRun` bounce, `s_mainStackRunner` /
+`wxWasmSetMainStackRunner` / `wxWasmRunOnMainStack`, `wx/wasm/private/
+mainstack.h`, `wasm/bindings/main_stack_runner.h` (+ its five embind includes),
+and KiCad's `TOOL_MANAGER::RunOnMainStackIfActiveTool` — the fork moves CLOSER
+to upstream. `wxWasmOnCoroutineStack()` and the captured main-stack bounds stay
+(the `fiberStackParks` probe uses them).
+
+Post-flip a nested loop opened from a tool parks the TOOL'S OWN context through
+`wxWasmYieldUntil` (context_sleep set the precedent for symmetric-lane parks) —
+which is what the bounce approximated from outside, minus the detour through
+the root. **Gates: battery 395/1 (nested green through the removal), strand 2/2
+(`closed=true refused-resumes=0` — the doc-19 pin holds with the mitigation
+deleted), kicad suite 139/1-equivalent.**
+
+Build-system note that cost two cycles: deleting a header leaves stale
+recorded deps in BOTH wx build trees (host `build-wasm/wxwidgets/.deps` and the
+docker volume `kicad-wasm-libs_kicad-build-cache:/cache/wxwidgets/.deps`) —
+remove the `.o` + `.o.d` pair in each before rebuilding.
+
+Flake watch: `ngspice-probe` "bg_run streams events live" has now failed twice
+under full-suite parallel load and passed 4/4 solo both times — a de-flake
+candidate, not a regression.
+
 ### Prod-provider smoke (2026-08-08) — done, with one pre-existing red bisected
 
 Against the live web stack (playwright-web config, reference backend :3060):

kicad

@@ -1 +1 @@
-Subproject commit 72b754b2c5552d7596ad5e5a31721eddb048f53e
+Subproject commit 452eb5260d8a73c2bd0dff8d2a53ab2c05f116be

wasm/bindings/eeschema_embind.cpp

@@ -59,7 +59,6 @@
 #include <tool/coroutine.h>
 #include <pcbjam_remote_lock.h>
 #include "collab_common.h"
-#include "main_stack_runner.h"
 #include "open_gate.h"
 #include "collab_presence_core.h"
 #include "collab_presence_style.h"

wasm/bindings/gerbview_embind.cpp

@@ -24,7 +24,6 @@
 #include <vector>
 #include <wx/app.h>
 #include <wx/string.h>
-#include "main_stack_runner.h"
 #include "open_gate.h"
 
 using namespace emscripten;

wasm/bindings/kicad_editor_embind.cpp

@@ -40,7 +40,6 @@
 #include <project.h>
 
 #include "pcbjam_libs_reload.h"
-#include "main_stack_runner.h"
 #include "open_gate.h"
 #include "timer_park.h"
 #include "fiber_park.h"

wasm/bindings/main_stack_runner.h

@@ -1,86 +0,0 @@
-/*
- * Main-stack runner: the KiCad half of wx's nested-loop bounce
- * (pcbjam docs/features/async/19, 20 D3).
- *
- * A quasi-modal's nested event loop parks its whole stack for the dialog's
- * lifetime. When that stack is a TOOL coroutine's, the park suspends the
- * fiber's body where the fiber layer cannot see it: the stale-fiber guard
- * quarantines the fiber, then REFUSES its own resume, and the dialog stops
- * responding to clicks (only the titlebar x still works, because that path is
- * ungated). That is the Symbol Properties hang.
- *
- * wx detects "this nested loop is about to park on a non-main stack" — it can,
- * cheaply and exactly, by comparing a frame address against
- * emscripten_stack_get_base()/end() — but it must not know what a coroutine
- * is. So it calls this runner, and KiCad's TOOL_MANAGER moves the loop onto
- * the main stack via its own RunMainStack mechanism, which suspends the
- * coroutine the legitimate way: a fiber swap the layer records
- * (swap_suspended = true), so no quarantine, no refused resume.
- *
- * This lives in pcbjam's binding layer rather than in KiCad or wx precisely
- * because it is the only place that may know about both.
- */
-#pragma once
-
-#include <wx/app.h>
-
-#include <eda_base_frame.h>
-#include <tool/tool_manager.h>
-
-#include <wx/wasm/private/mainstack.h>
-
-namespace pcbjam_main_stack
-{
-
-/**
- * Run aFunc on the main stack if a tool coroutine is currently active.
- *
- * Returns 1 when the body has been run (bounced, or run inline because there
- * was no coroutine to bounce off), 0 when there was nothing to run it with —
- * no frame or no tool manager — in which case wx parks in place exactly as it
- * did before this hook existed.
- */
-inline int run_on_main_stack( void ( *aFunc )( void* ), void* aArg )
-{
-    if( !wxTheApp )
-        return 0;
-
-    auto* frame = dynamic_cast<EDA_BASE_FRAME*>( wxTheApp->GetTopWindow() );
-
-    if( !frame )
-        return 0;
-
-    TOOL_MANAGER* toolMgr = frame->GetToolManager();
-
-    if( !toolMgr )
-        return 0;
-
-    // RunOnMainStackIfActiveTool runs the body inline when no coroutine is
-    // running. Either way the body HAS run, so report it as handled — letting
-    // wx fall through would run the nested loop a second time.
-    bool ran = false;
-
-    toolMgr->RunOnMainStackIfActiveTool(
-            [aFunc, aArg, &ran]()
-            {
-                ran = true;
-                aFunc( aArg );
-            } );
-
-    return ran ? 1 : 0;
-}
-
-/**
- * Installs at static-init time. Only stores a function pointer, so it is safe
- * before wx exists; every lookup above happens lazily per call, since frames
- * come and go. Included by more than one binding TU — setting the same pointer
- * twice is idempotent.
- */
-struct INSTALLER
-{
-    INSTALLER() { wxWasmSetMainStackRunner( &run_on_main_stack ); }
-};
-
-inline INSTALLER g_installer;
-
-} // namespace pcbjam_main_stack

wasm/bindings/pcbnew_embind.cpp

@@ -52,7 +52,6 @@
 #include <nlohmann/json.hpp>
 #include "collab_common.h"
 #include "collab_presence_core.h"
-#include "main_stack_runner.h"
 #include "open_gate.h"
 #include "timer_park.h"
 #include "fiber_park.h"

wasm/bindings/pl_editor_embind.cpp

@@ -17,7 +17,6 @@
 #include <wx/string.h>
 #include <wx/window.h>
 #include <nlohmann/json.hpp>
-#include "main_stack_runner.h"
 #include "open_gate.h"
 #include <eda_draw_frame.h>
 #include <kiid.h>

wxwidgets

@@ -1 +1 @@
-Subproject commit 49cd4c53b6ea1469b6fb1ef5fb867487f231dc97
+Subproject commit a8d9ece31f9130dc5b8726924fd2f6f34f1b305f