M3.2: the action classifier

What the fast path calls unknown is judged by an independent model call
on the item's classifier role (L4), before it runs.

- nisse_dev.loop.classifier: it sees the action and the agreed scope
  (project, repository, issue number, the restatement the operator said
  go to), built in code; never the transcript, the issue's text, tool
  output or the driver's reasoning. Its verdict is a tool call: safe
  runs; in_scope runs and is reported in the thread; needs_discussion
  asks, as a dangerous action does. An error, no verdict or an unknown
  one fails closed. Verdicts are cached per item, agreed revision and
  action. A helper is refused what needs discussion.
- action_verdict gains source, model and the classifier's exact input;
  details shows the source. An allow after the classifier asked is an
  override. scripts/classifier-evals.py exports the judgements from a
  store, read-only; tests/integration/classifier_cases.yaml is the seed
  set, run per model with --capability-models.
- The fast path's delete rule: deleting on the build VM is contained;
  only what breaks the host (system and home directories) stays
  dangerous, since in tests the build VM is the test machine.
- The classifier role is the local model in the example config.
- The property walk gains a classifier answering at random, junk and
  failures included; dangerous_only_when_allowed now covers its
  verdicts (checked against a mutant that runs them all).

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPQ14L3LikyefCMFBqEbKE

nisse-dev/src/nisse_dev/canonical.py

@@ -93,7 +93,12 @@ class ActionVerdict:
     effect: str  # harmless | contained | unknown | dangerous | refused
     rule: str
     reason: str
-    decision: str  # ran | refused | asked | allowed
+    decision: str  # ran | refused | asked | allowed | classified
+    # Who decided: the fast path's rules, or the classifier (L4), with the
+    # model it ran on and exactly what it was shown (the evaluation set, L9).
+    source: str = "fast_path"
+    model: str = ""
+    input: str = ""
 
 
 @dataclass(frozen=True)