Param.is_va_list (G31 Phase C continued) inherits the toolchain- identity-probe gap above, rather than being a new problem

Index: Known gaps

Status (re-verified 2026-10-09 at 456989f): OPEN. snapshot_reliability.py:182 and fact_registry_schema.py:273 have clang_va_list_facts_reliable as a plain flag without target identity, and no toolchain-identity probe exists yet (see entry 9).

Its extraction predicate (dumper_clang_qualifiers._clang_param_is_va_list) is deliberately scoped to the one ABI verified here — x86-64 System V — and a snapshot from an unrecognized target already degrades to a conservative False (see the function's own docstring). What's still open (Codex review, fresh evidence): the snapshot-level reliability flag (AbiSnapshot.clang_va_list_facts_reliable) records only "did the fixed extractor run", not "against which resolved target" — so two genuinely-different-target clang snapshots (x86-64 vs. AArch64, say) can both read as reliable, and a real cross-architecture comparison (which this tool's comparability layer permits in general) could read the x86-64 side's real detections against the AArch64 side's uniform False as a spurious PARAM_BECAME_VA_LIST/PARAM_LOST_VA_LIST. No header-AST fact has resolved-target validation today, not just this one — closing it here alone would be an inconsistent one-off fix for a structural gap; it belongs with the toolchain-identity probe above once that lands.