User request: soak FCL launches on the Y700 (Magma, Espryt control) to root-cause the "silent Magma death after MobileGL init" seen once in the P13 FCL smoke. User decision afterwards: the cause is FCL's, leave FCL as-is, no MobileGL workaround; recorded as a debt (../../DEBTS.md, "FCL game process can die silently").

Result

Every silent death is ApplicationExitInfo reason=2 (SIGNALED) status=34 - signal 34 is SIGRTMIN+2, the wake-up signal of Android libcore's AsynchronousCloseMonitor. No tombstone, no kgsl/GPU fault line, no debuggerd output, in any death.

Mechanism (ftrace signal_generate / signal_deliver filtered on sig==34, plus a 0.5 s sampler of /proc/<pid>/status SigCgt):

FCL's game process starts with Android's handler set (SigCgt 0x6e400084f8, bit 33 = sig 34 caught).
About 0.5 s after FCL logs Renderer: MobileGLDev... (JVM start for the game), the whole set is replaced by the JVM's (SigCgt 0x1005cef, later 0x2000000001005cef): sig 34 is no longer caught.
FCL's own okhttp stack (Okio Watchdog thread) times out a blocked read and sends sig 34 to the reading onPool-worker-N thread (AsynchronousCloseMonitor::signalBlockedThreads, code=-6 = SI_TKILL).
With the default disposition the kernel takes the fatal fast path: signal_generate with no signal_deliver, and the whole process dies. In the relaunched launcher process the same watchdog's signals are delivered to libcore's handler (sa_handler=79a72f3fa0) and nothing happens.

Renderer-independent: reproduced with the P13 library on both backends and with the pre-P13 (P12 end, 743f4e8e) library; several deaths happen before MobileGL has logged anything beyond FCL's renderer line. Rate depends on whether FCL's background network read times out in that window (network-dependent), not on the GL library. Untested with non-MobileGL renderers.

Fix belongs in FCL: save libcore's SIGRTMIN+2 sigaction before creating the JVM and restore it after (or do not reset that signal). Left for the user.

Soak sizes

soak	library	runs	deaths (all status=34)
clean (`soak-p13-clean-summary.txt`, `soak2.sh` with the SigCgt sampler and per-run ftrace)	P13 FCL lib at `c1e985c8`	30 (22 Magma, 8 Espryt)	18: Magma 13/22, Espryt 5/8
P12 control (`soak-p12-control-summary.txt`)	P12 end `743f4e8e`	10 Magma	2

Earlier P13 runs (first 5-run soak) are not counted: two soak scripts were found driving the phone at once and force-stopping each other's runs; soak2.sh now takes a lock.

Per-death evidence kept here for one representative death (clean run 4, Magma): the ftrace excerpt (run004-magma-ftrace-signal34.txt - pid 27854 is the dying process's worker, generated with no delivery), the SigCgt transitions (run004-magma-sigcgt-transitions.txt) and the logcat lines (run004-magma-logcat-excerpt.txt). The full per-run logcat/dmesg/ftrace/exit-info captures stayed in the session scratchpad and were not committed.

Device restored afterwards: original FCL libMobileGL.so (md5 checked) and config.json, ftrace signal events and tracing_on off, svc power stayon false, anland relaunched.