spec-guards: ring-096 drift and 8 published-figure pins were hidden behind the seal step #6553

Refs #6092

spec-guards has not passed on master since 2026-09-16. The seal-currency step failed first, and that hid the steps after it. #6546 fixes the seal step. On that PR the job now gets one step further and fails on failures that were already on master.

Measured on the Railway t27c lab at master a406f41, with t27c built from master:

1. tools/check_ring_spec_drift.py exits 1. ring-096-rust against specs/numeric/formats.t27 is DRIFTED: 6 functions are shared and 5 have different signatures.
   • The spec declares stub signatures such as fn gf16_to_f32(x: u16) -> gf16 { } and fn quantize_value(x: f32, fmt: Format) -> gf16 { }.
   • gen-rust lowers these to u16/f32 stubs.
   • The hand ring rings/ring-096-rust/src/lib.rs uses f64.
2. tools/published_figures.py --check exits 1. 8 pinned figures have drifted:
   • []T{} literals, x.len(), x.len, len(x), a::b::c, OP_*, abs(, and test blocks (pinned 14314, measured 15067).
   • The pins live in the FIGURES list in tools/published_figures.py.
3. check_duplicate_declarations.py and diagnostic_capacity.py exit 0. The CONVERGED-pairs step after them was not run here.

Both repairs touch non-t27 files: either the hand ring, or the Python pin table. The alternative is to change the meaning of formats.t27. Under the 2026-10-05 no-foreign-code rule, this needs an owner decision.

Boundary

• specs/numeric/formats.t27
• rings/ring-096-rust/src/lib.rs
• tools/check_ring_spec_drift.py
• tools/published_figures.py

User Scenarios

• Given the spec-guards pipeline runs on master after chore(seals): re-seal the 3 stale gen-hash seals that keep spec-guards red #6546 lands, When tools/check_ring_spec_drift.py executes against specs/numeric/formats.t27 and rings/ring-096-rust/src/lib.rs, Then it exits 0 because the 5 drifted signatures in ring-096-rust match the spec declarations.
• Given the spec-guards pipeline runs on master after chore(seals): re-seal the 3 stale gen-hash seals that keep spec-guards red #6546 lands, When tools/published_figures.py --check executes, Then it exits 0 because the 8 pinned figure counts in the FIGURES table match the freshly measured values.

Requirements

• FR-001: The hand-written ring rings/ring-096-rust/src/lib.rs MUST align its 5 drifted function signatures with the stub signatures declared in specs/numeric/formats.t27 (e.g., gf16_to_f32, quantize_value using f64 per the ring, or the spec changed to f64).
• FR-002: The FIGURES list in tools/published_figures.py MUST be updated so that all 8 pinned figure counts (including test blocks: pinned 14314 → measured 15067) match the current measured values from the codebase.
• FR-003: tools/check_ring_spec_drift.py MUST exit 0 when run against specs/numeric/formats.t27 and rings/ring-096-rust/src/lib.rs after the signature alignment.
• FR-004: tools/published_figures.py --check MUST exit 0 after the FIGURES table is updated to the current measured values.

Success Criteria

• python tools/check_ring_spec_spec_drift.py specs/numeric/formats.t27 rings/ring-096-rust/src/lib.rs exits 0
• python tools/published_figures.py --check exits 0
• The spec-guards job on master passes all steps including CONVERGED-pairs (previously hidden)