nx_riscv_spec_oracle_gate.nx

nx_riscv_spec_oracle_gate.nx -- THE ORACLE ROW FOR `nishios`: corroborate the mcause exception codes our kernel gates depend on against the OFFICIAL RISC-V PRIVILEGED SPECIFICATION -- a document WE DID NOT WRITE. WHY: nx_evidence_verdict.nx clause 5 TRIANGULATION needs >=2 method classes with >=1 MECHANISTIC, and defines ORACLE as agreement with external ground truth. Every nishios gate is MECH and SELF-AUTHORED, so the domain carried ONE class and min_classes=2 made PROVEN unreachable. This is the second class. THE SUBJECT: knowledge/specs/EXTERNAL-riscv-priv-machine.adoc -- the machine-level chapter of the RISC-V ISA manual, fetched 2026-08-15 from riscv/riscv-isa-manual (main) over the sovereign HTTPS stack, preamble stripped, copy byte-verified. 173,346 B of CLEAN ASCIIDOC SOURCE. WHY NOT THE PDF -- MEASURED, AND IT IS THE WHOLE REASON THIS FILE EXISTS. The official v1.12 PDF was fetched first and converted with nx_pdf_text. Its text layer is KERNED, so extraction SPLITS WORDS (`Privileged Arc hitectures`, `this do cumen twas`) and drops ligatures (`simpli???ed`). Grepping THAT artifact for "Environment call from U-mode" returned 0 matches, corpus_complete=1 -- while the spec plainly contains it, at line 1875 of THIS file. ******A DEGRADED RENDERING OF A CORRECT SOURCE PRODUCES CONFIDENT FALSE ABSENCES, AND AN ORACLE BUILT ON IT WOULD ACCUSE THE ESTATE OF DEVIATING FROM A STANDARD IT ACTUALLY FOLLOWS. A FALSE RED AGAINST AN EXTERNAL AUTHORITY IS THE MOST CREDIBLE WRONG ANSWER AVAILABLE. Two renderings of ONE document disagreeing is what located the defect in the RENDERING rather than in the spec or in us. WHAT IT CHECKS, and the CEILING STATED PLAINLY. The spec's exception table is AsciiDoc: a column of codes and a parallel column of descriptions. This gate does NOT claim to parse that table. It asserts the STRUCTURE our gates actually depend on: T1 both mcause descriptions exist in the official text at all T2 U-mode precedes M-mode => mcause(U) < mcause(M), i.e. they are DISTINCT and ordered T3 exactly TWO description entries sit between them (S-mode, _Reserved_) => mcause(M) - mcause(U) == 3, which with the U=8 anchor pins M=11 That is the RELATIONSHIP _umode_gate relies on (ecall-from-U => 8, its MPP=M control => 11). It pins ORDER and GAP against external text; it does not re-derive the absolute integers from the table's code column. **CORROBORATION, NEVER DERIVATION** -- the same ceiling the virtio oracle carries. exit: gv_verdict (0 GREEN / 1 RED / 3 SKIP) license_tier: ORIGINAL. Read-only. No hw writes (Rule 26).