T05: the lab and its labelled mutation catalogue

lab/app.py (users, tenants, auth, resources, sharing, read/write, revoke,
audit), lab/http_api.py (JSON API + browser UI, stdlib only), 20 labelled
composable version-stamped mutations, ground-truth matrix. 48 tests pass.

Detection against the reference scenario: MECHANICAL 0/10 flagged (correct),
DEFECT 6/6, SEMANTIC 2/4 with both inert cases declared.

- F-0002: M16 and M18 initially escaped detection entirely. A use case
  protects exactly what it asserts. Resolved by adding two claims already
  stated as intent in INTENT.md; the six-mutation catalogue would never have
  surfaced this.
- test-id axis added: stable selectors survive most UI mutations, which would
  make H-001 trivially false. Mutations now vary on preserves_test_ids so the
  hypothesis is analysed split by that axis rather than rigged.
- M12 (semantic deferred revoke) and M19 (defect race) are behaviourally
  identical and asserted as such - the discrimination problem as a test.

lab/minimal.py removed; superseded by lab/app.py.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 1629012@bnt-lap001
Assistant-Session: 78d4fb13-8a1e-474b-87a3-9b9261c49a39

research/concepts/fitness-map.md

@@ -1,6 +1,6 @@
 # Concept ↔ Implementation Fitness Map
 
-**Updated:** 2026-08-22 (TD-WP-0002-T04)
+**Updated:** 2026-08-22 (TD-WP-0002-T05)
 
 Traces each important concept to the implementation, experiment and evidence that
 support it. **Unsupported entries are the point of this map** — a concept with no
@@ -29,7 +29,7 @@ were aspirational, not evidenced.
 | `C-semantic-action` | C1 | `actions.py` | E-001 | — | Does identity survive restructuring better than a recorded sequence? (H-001) |
 | `C-oracle-independence` | C1 | `runner.py`, `oracles.py` | E-001, E-003 | — | Independence of components ≠ independence of belief. (H-004) |
 | `C-evidence-pack` | C1 | `evidence.py` | — | — | What is the minimum sufficient for replay? |
-| `C-observation-channel` | C1 | `lab/minimal.py` | — | — | **D-07** — required of every system under test. Adoption cost unknown. |
+| `C-observation-channel` | C1 | `lab/app.py` | — | — | **D-07** — required of every system under test. Adoption cost unknown. |
 | `C-adaptation` | C1 | — (T08) | E-001 | — | (H-002) |
 | `C-classification` | C1 | — (T08) | E-001, E-003 | — | Decision table is total on paper; unexercised. |
 | `C-crystallization` | C1 | — (T09) | E-002 | — | (H-003) |
@@ -41,7 +41,7 @@ were aspirational, not evidenced.
 | `C-campaign` | C0 | — | — | — | Deferred. |
 | `C-metabolism` | C0 | — | — | — | Deferred. Depends on C-energy. |
 | `C-retirement` | C0 | — | — | — | Deferred. Depends on C-energy. |
-| `C-security-mutation` | C1 | — | E-003 | — | Catalogue exists; no derivation mechanism. |
+| `C-security-mutation` | C1 | `lab/mutations.py` | E-003 | `lab/GROUND-TRUTH.md` | Catalogue is hand-written; no derivation mechanism from use cases yet. |
 
 ## Orphan check
 

research/findings/F-0002-scenario-coverage-gap.md

@@ -0,0 +1,74 @@
+---
+id: F-0002
+type: framework-finding
+class: FRAMEWORK_LIMITATION
+status: resolved
+discovered: "2026-08-22"
+resolved: "2026-08-22"
+discovered_by: TD-WP-0002-T05
+workplan: TD-WP-0002
+task: TD-WP-0002-T05
+---
+
+# F-0002 — Two seeded defects were invisible to the reference scenario
+
+## Observation
+
+On first running the reference scenario against the twenty labelled mutations,
+**six of six DEFECT mutations should have failed; only four did.**
+
+| Mutation | Defect | Verdict before | Why it escaped |
+|---|---|---|---|
+| M16 | A READ grant confers WRITE | `PASS` | No claim mentioned writing. The scenario never attempted one. |
+| M18 | Revocation is not audited | `PASS` | `i-audit-append-only` checks *ordering*, not *completeness*. A trail missing an entry is still ordered. |
+
+Both passed cleanly. Nothing was flaky, nothing was ambiguous, and no oracle
+reported `INCONCLUSIVE` — the framework simply had nothing to say, confidently.
+
+## Why it matters
+
+This is the failure mode most likely to be mistaken for success. A green run
+against a lab carrying a seeded privilege escalation looks exactly like a green
+run against a correct system. Had the catalogue been the six mutations the
+milestones document originally sketched, this would not have surfaced at all —
+which is the concrete argument for the larger catalogue, now made from evidence
+rather than from assertion.
+
+It also sharpens what a verification asset is: **a use case protects exactly what
+it asserts, and not one thing more.** Coverage is a property of the claim set, not
+of the framework. No amount of adaptation, crystallization or energy scoring
+compensates for an assertion nobody wrote.
+
+## Resolution
+
+Path 1 — the implementation changes to match the concept.
+
+Two claims were added to the reference use case, both `Provenance.HUMAN` and both
+derivable from `INTENT.md` rather than from watching the lab:
+
+- `c-bob-cannot-write` — "A READ grant does not let Bob write R".
+  `INTENT.md` § Security by Use-Case Mutation already derives this exact question
+  from the reference use case: *"Can Bob write when only read permission was
+  granted?"* It was always part of what sharing means; it had simply never been
+  written down as an assertion.
+- `c-revoke-audited` — "Revocation is recorded in the audit trail". Enforcement
+  being correct is not sufficient: an access change nobody can later evidence is
+  a compliance failure even when the access itself is right.
+
+Supporting changes: the lab gained a write path and the observation channel a
+non-destructive `probe_write`.
+
+Both defects are now detected. DEFECT detection is 6/6, and
+`test_every_defect_is_detected` fails the suite if that ever regresses.
+
+## Note on provenance
+
+These claims were added *after* observing that mutations escaped, which is
+uncomfortably close to fitting assertions to the lab. They are admissible because
+both were already stated as intent in `INTENT.md` before any lab existed — the
+finding revealed a transcription gap, not a new requirement. Had the intended
+behaviour not already been on record, the correct resolution would have been to
+escalate to a human, not to write the claim.
+
+That distinction is exactly what `Provenance` exists to make checkable, and this
+finding is the first case where it did real work.