---
id: E-001
title: Mechanical recovery and defect discrimination over the labelled mutation set
status: EXECUTED
hypotheses: [H-001, H-002, H-004]
task: TD-WP-0002-T08
created: "2026-08-22"
---

# E-001 — Mechanical recovery and defect discrimination

## Design

Run the same verification asset against every labelled lab mutation (T05),
in two arms:

- **arm A** — semantic action realized by the agentic driver;
- **arm B** — a recorded selector-based sequence captured against the baseline,
  built with the most robust selector strategy reasonably available.

Arm B is the control for H-001 and must actually be run.

## Outcomes recorded per run

surface diff (S1) · postcondition met and surface used (S2) · oracle verdicts
(S3) · classification emitted · claim/invariant diff (expected empty) ·
tokens · wall time · retries.

## Decision rules

- **False Adaptation Rate > 0** → stop. H-004 falsified; redesign, do not tune.
- Arm B recovery ≥ arm A recovery → H-001 falsified.
- Recovery achieved with a non-empty claim diff → H-002 falsified *and* a
  framework defect, since D-02 forbids the write path.

## Status

`EXECUTED` 2026-08-22 (T08). Arm A run over 23 mutations; arm B over
the 12 mechanical ones. Results in H-001 and H-004. FAR 0/7.

## Expanded measurement — 2026-09-28 (TD-WP-0003-T03)

38 mutations, including ten that drop test ids and seven new paired structural
controls. Discovery and recorded selectors both pass 17/17 preserved-id cases;
on dropped ids discovery passes 9/10 and recorded selectors 0/10. M22 remains
unrealizable. The full journey accepts 26/27 mechanical cases; FAR remains 0/7
on the unchanged defect set. Claim/provenance indices remain unchanged.

Reproduce: `PYTHONPATH=src:. python3 tools/measure_e001.py /tmp/e001.json`.
[Raw result](../evidence/2026-09-28-e001.json).
These selected and correlated synthetic HTML cases do not establish population
reliability, visual/browser coverage, model capability or economics. See
[review](../../docs/TestDriverGeneralisationReview.md) for the mechanism list and
limits. H-001 remains supported only in the narrowed identifier-loss setting.