T09: crystallization

A stable agentic realization becomes deterministic code. All four exit
criteria met; 163 tests pass.

- crystallization.py: trajectory capture, stability assessment requiring the
  same path across several runs, CrystallizedDriver, pytest codegen
- crystallized/test_grant_access.py: generated, runs with no model, carries
  its lineage in the docstring
- descendant preserves the ancestor's oracle set, agrees with it across five
  lab versions, and still catches a seeded defect
- reversibility shown both ways via new M24 (grant endpoint renamed): the
  frozen descendant fails loudly rather than searching, and the agentic
  ancestor recovers from the same mutation

F-0007 (open): the 54% cost reduction must not be quoted in support of the
thesis. The T07 runtime is token-free, so the measured saving is one page
fetch, one parse and a two-candidate scoring pass. The saving the concept
actually claims - tokens, latency, retry variance - is unmeasured. Together
with F-0005 this makes a bounded live-model experiment the highest-value next
investment.

Assertions in the generated test are imported rather than restated, so it is
not fully standalone. Deliberate: paraphrased claims would be a second
unverified statement of intent.

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

lab/mutations.py

@@ -91,6 +91,7 @@ def _m10(app): _m(app, denied_status=401)
 # Intended behaviour changed. A human must decide; test-driver must not.
 
 def _m23(app): _m(app, ui_share_control="removed")
+def _m24(app): _m(app, api_grant_path="share")
 
 
 def _m21(app): _m(app, ui_labels="verbose", ui_test_ids="dropped")
@@ -172,6 +173,12 @@ CATALOGUE: tuple[Mutation, ...] = (
              "generalises or merely pattern-matches known field names.", _m22,
              preserves_test_ids=False),
 
+    Mutation("M24", "The grant endpoint is renamed", "MECHANICAL", "api",
+             "/grant becomes /share and the old path stops working. The agentic "
+             "arm recovers by reading the form; a frozen path cannot. This is the "
+             "reversibility case — a crystallized asset must fail loudly here, "
+             "not search.", _m24),
+
     Mutation("M23", "Sharing control removed from the UI, API left open", "DEFECT", "ui",
              "The surface-substitution trap. A driver that 'recovers' by calling "
              "the API has routed around a control, not adapted to a change — the "