Keep the home memo form when the decision overview fails

The overview is orientation only; a store, policy or engine failure while
listing now shows a notice instead of an error page, so the memo form and
sign-out stay reachable.

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

Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 359683@bnt-lap001
Assistant-Session: eebdc939-7a9b-4e50-9d39-c8437e8a14ec

informed_decision/web.py

@@ -188,7 +188,7 @@ class App:
         if method == "GET" and path == "/":
             if session:
                 content = (f"<p>Signed in as {html.escape(session.subject)}.</p>"
-                    + (overview_section(self.review.overview(session)) if self.review is not None else '')
+                    + (self._overview(session) if self.review is not None else '')
                     + ('<h2>Open a decision review</h2><p>Enter the memo identifier supplied with your review request.</p>'
                        '<form method="get" action="/review"><label>Memo identifier <input name="memo_id" required maxlength="256"></label>'
                        '<button type="submit">Open review</button></form>' if self.review is not None else
@@ -201,6 +201,19 @@ class App:
             return 200, document("Informed Decision", content, session.subject if session else None), "text/html", []
         return 404, "Not found.", "text/plain", []
 
+    def _overview(self, session):
+        # The overview is orientation only. Its failure must never take the
+        # memo form, sign-out or an unresolved-entry recovery path with it.
+        try:
+            return overview_section(self.review.overview(session))
+        except ReviewError as exc:
+            if exc.code == "session_expired":
+                raise
+        except (PolicyError, ApprovalEngineError, StoreError, sqlite3.Error, ValueError, KeyError, TypeError):
+            pass
+        return ('<h1>Your decisions</h1><div class="notice warning" role="status">Your decisions could not be '
+                'listed right now. You can still open a review by its memo identifier.</div>')
+
     def _form(self, environ, session):
         if environ.get("HTTP_ORIGIN") != ORIGIN:
             raise ReviewError(403, "invalid_form")

tests/test_review_controller.py

@@ -407,3 +407,11 @@ def test_home_without_session_shows_sign_in_only(review):
     r=call(app,'/')
     assert 'Sign in with KeyCape' in r['body'] and 'Your decisions' not in r['body']
     assert controller.store.policy_observations()==[]
+
+
+def test_home_keeps_the_memo_form_when_the_overview_fails(review,monkeypatch):
+    controller,session,app,*_=review
+    def broken(subject):raise sqlite3.OperationalError('disk')
+    monkeypatch.setattr(controller.store,'memos_for',broken)
+    r=home(review)
+    assert r['status']==200 and 'could not be listed right now' in r['body'] and 'Open a decision review' in r['body']