Adds a read-only MSVC RTTI traversal helper (`read_class_at_this`)
and a `probe_create_stack_classes` integration that walks each
captured back-chain frame for handle creates in `--trace-handles-focus`
and probes each frame's most-likely `this` candidate (live r31/r30/r3
for frame 0; saved-r31/r30 from the prologue spill area at [fp-12]/
[fp-16] for deeper frames). False-positive guard rejects the CRT
static-init iterator pattern (vtable's first two slots must be image-
range function pointers — PPC instruction words like `mflr r12` are
not in 0x82xxxxxx).
`dump_thread_diagnostic` now takes `&GuestMemory` so the FOCUS report
prints, for each parked waiter, a WAIT-THREAD block with full back-
chain frames and per-slot saved-register dump for offline lookup.
End-to-end finding (-n 500M producer-trace):
* Handle 0x100c dispatcher = 0x828F3D08 (image rdata; verified by
sub_82181750 disasm + xref table). [this+0] = -1 sentinel — POD
job queue, NOT a C++ polymorphic class.
* Handle 0x15e0 dispatcher = 0x828F4070 (same shape).
* Handle 0x1004's 8-instance pool members still TBD (MSVC ctors
didn't preserve `this` in r31).
* 0x42450b5c is a separate audit class (heap-allocated, parks via
non-`do_wait_single` path).
Decisive xref audit: every reference to 0x828F3D08 / 0x828F4070 in
the static analysis is in a ctor or the CRT init driver. NO producer
code references either dispatcher base. Confirms `signal_attempts=0`
is unreachable-producer, not broken-producer.
Tests: 581 → 586 green (+5: RTTI-intact / RTTI-stripped / non-object
/ cstring / probe_create_stack integration). `--stable-digest -n
100M` instructions=100000002 unchanged. Master HEAD prior: 6440261.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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