# Gate 3 increment 2 numerical-contract report

Date: 2026-08-15
Exact base: `369417fbb45d25e544a72246abb05e21d1ac00e0`
Evidence scope: the containing commit, resolved with `git rev-parse HEAD`
Canonical merge: `2c2b38b501f94af46ffac3a772f7bf9475154dc5` (PR #102,
rebase merged)
Status: PASS; exact-head audit, rebase merge, post-merge CI, and issue #100
reconciliation complete

## Results

| Gate | Result |
|---|---|
| Mandatory CPU matrix | Python 3.10, 3.11, and 3.12: 1,789 passed and 6 conditional skips on each interpreter; 0 failures |
| Repository coverage | 76.48% statements; 63.00% branches |
| Mature CPU scope | 93.05% statements; 82.41% branches |
| Changed executable lines | 222/222 (100%) against the exact base |
| Touched production modules | 4/4 pass exact-base line and branch no-regression |
| Numerical seam | `numerical_contracts.py`: 100% statements and 100% branches |
| Whitened SVD | `whitened_svd.py`: 98.21% statements and 93.33% branches |
| Selective mutation | 1,325/1,538 killed (86.15%); 208 survived; 5 timed out; 0 no-test or segfault results |
| Mutation runtime | 1,107.16s for covered-line preparation, stats preparation, and full execution; 730,132 KiB maximum parent RSS |
| Installed offline vertical slice | Five real prompt pairs exercise installed CLI mutation, checkpoint metadata/state change, reload, installed reporting, and JSON/CSV output without network or accelerators |

## Contracts added

1. Independent float64 reference oracles cover row orthogonalization, harmless
   principal-component removal, shield-atom residualization, coefficient
   selection, and standard/transposed weight projection.
2. Metamorphic checks cover projection idempotence, direction-scale invariance,
   orthogonality, norm behavior, unsupported layouts, non-finite coefficients,
   zero/tiny boundaries, integer restoration, and half/bfloat stable compute.
3. Whitened SVD is checked against independent covariance/eigendecomposition/SVD
   oracles, activation-shape validation, degenerate variance, permutation/sign
   behavior, dtype promotion, layer ordering, and deterministic CPU behavior.
4. A bounded `--prompt-pairs-file` seam permits installed offline integration
   without weakening the built-in 842-pair default. The loader rejects malformed,
   oversized, non-UTF-8, NUL-containing, blank, unequal, and undersized inputs.
5. Required mutation targets fail closed when absent, stale, empty, or mapped to
   no tests. No-test exit-code interpretation is pinned to mutmut 3.7.0 while
   ordinary metadata validation remains portable to the Python 3.10 test job.
6. Mutation execution uses three fresh processes: covered-line preparation,
   function/test stats preparation, then execution-only mutmut. Clean and
   forced-fail preflights run in subprocesses so the fork parent never inherits
   pytest/Torch teardown state.
7. The deep gate uses eight single-threaded workers, a 30-second minimum wall
   allowance (`timeout_constant = 2.0`, mutmut multiplier 15), and a 45-minute
   hosted hard cap. A known infinite-growth mutant was independently replayed
   and bounded before the complete campaign.

## Scope and release decision

This increment implements Gate 3 bounded delivery item 2. It does not reopen
ordinary feature work: items 3–7, conditional-evidence reconciliation, and the
final canonical Gate 3 publication remain open. CUDA, MPS, MLX, network,
download, remote, and operator-UI mappings were not changed; their six local
skips remain governed by item 8 rather than being treated as CPU-gate failures.

The local mutation artifacts were preserved in
`/tmp/obliteratus-gate3-repair-mutation-CJRWT2/quality-evidence/` for the local
audit. The hosted PR and post-merge CI artifacts are the canonical evidence.
