fix(calendar): redact script diagnostics, and page the calendar list

Three findings from CodeRabbit, all valid.

Raw subprocess output was being returned to the client -- the script's
stderr on one path, and its own error payload on another. CodeQL flagged
the same line. That script handles OAuth client secrets and interpolates
exceptions into its messages, so either could carry a secret or a path.
Both now go to the log unredacted, where they are worth having in full,
and reach the client through a redactor.

That redactor already existed inside describe_exception, which only
takes exceptions. Split out as redact_text: an exception is not the only
thing worth returning, and a subprocess's stderr is just as capable of
quoting a token.

calendarList.list returns 100 entries per page by default, caps at 250,
and hands back a nextPageToken when there are more. Reading one page
would have hidden calendars from the picker with nothing to say the list
was cut short. It now pages, asking for 250 at a time, bounded at ten
pages so a malformed token cannot spin.

And a test helper was a lambda where ruff wants a def.

The five new tests fail against the previous commit.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Udr6MfaFLUPhX5Fgo67Jf5

web_interface/blueprints/api_v3.py

@@ -22,7 +22,7 @@ logger = logging.getLogger(__name__)
 from src.web_interface.api_helpers import success_response, error_response, validate_request_json
 from src.web_interface.errors import ErrorCode
 from src.web_interface.secret_helpers import find_secret_fields, separate_secrets
-from src.web_interface.error_handler import describe_exception
+from src.web_interface.error_handler import describe_exception, redact_text
 from src.plugin_system.operation_types import OperationType
 from src.web_interface.validators import (
     validate_file_upload
@@ -7312,6 +7312,11 @@ def upload_calendar_credentials():
         logger.error('Error in upload_calendar_credentials', exc_info=True)
         return jsonify({'status': 'error', 'message': 'An error occurred; see logs for details', 'details': describe_exception(e)}), 500
 
+# calendarList.list pages at 250 entries maximum. Ten pages is far past any
+# real account and exists only so a malformed nextPageToken cannot spin here.
+_CALENDAR_LIST_MAX_PAGES = 10
+
+
 def _calendar_plugin_dir() -> Optional[Path]:
     """Where the calendar plugin is installed, or None if it is not."""
     if api_v3.plugin_manager:
@@ -7363,9 +7368,15 @@ def _run_calendar_registration(plugin_dir: Path, stdin_payload: str):
         if isinstance(payload, dict):
             return payload, None
 
-    detail = (result.stderr or result.stdout or '').strip()[:300]
+    raw = (result.stderr or result.stdout or '').strip()
+    # The unredacted text goes to the log, where it is worth having in full.
+    # What comes back over HTTP is redacted: this is a script that handles
+    # OAuth client secrets, and its stderr can quote them.
+    if raw:
+        logger.error('calendar_registration.py failed (exit %s): %s',
+                     result.returncode, raw)
     return None, 'Authentication script produced no result%s' % (
-        ': %s' % detail if detail else '')
+        ': %s' % redact_text(raw) if raw else '')
 
 
 @api_v3.route('/plugins/calendar/authenticate', methods=['POST'])
@@ -7404,8 +7415,14 @@ def authenticate_calendar():
             return jsonify({'status': 'error', 'message': error}), 500
         if payload.get('status') != 'success':
             # The script's own diagnosis is more useful than anything that
-            # could be reconstructed here.
-            return jsonify(payload), 400
+            # could be reconstructed here -- but it interpolates exceptions
+            # into its messages, so it reaches the client redacted and the
+            # original goes to the log.
+            logger.error('calendar authentication failed: %s', payload)
+            safe = dict(payload)
+            safe['message'] = redact_text(str(payload.get('message', '')
+                                              or 'Authentication failed'))
+            return jsonify(safe), 400
         return jsonify(payload)
 
     except Exception as e:
@@ -7469,7 +7486,26 @@ def list_calendar_calendars():
             }), 400
 
         service = build_google_service('calendar', 'v3', credentials=creds)
-        entries = service.calendarList().list().execute().get('items', [])
+
+        # calendarList.list returns 100 entries per page by default and caps at
+        # 250, handing back a nextPageToken when there are more. Taking only
+        # the first page would silently hide calendars from the picker, and the
+        # user would have no way to tell the list was truncated.
+        entries = []
+        page_token = None
+        for _ in range(_CALENDAR_LIST_MAX_PAGES):
+            response = service.calendarList().list(
+                maxResults=250, pageToken=page_token).execute()
+            entries.extend(response.get('items', []))
+            page_token = response.get('nextPageToken')
+            if not page_token:
+                break
+        else:
+            # 2500 calendars in, something is wrong with the account or the
+            # token is looping; show what was collected rather than spin.
+            logger.warning(
+                'calendarList paging stopped at %d pages with more remaining',
+                _CALENDAR_LIST_MAX_PAGES)
 
         calendars = [{
             'id': entry.get('id'),