Do you need to file an issue?

• I have searched the existing issues and this bug is not already filed.
• I believe this is a legitimate bug, not just a question or feature request.

Describe the bug

Guided Learning choice questions have an inconsistent data contract between
mastery_quiz, ask_user, deterministic grading, and the Question Bank.

This causes two user-visible failures:

1. Some Question Bank entries display only A, B, C, and D, without the
   corresponding option text.
2. A correct card selection can be graded as wrong when mastery_quiz stores
   an option-body fragment such as Step 6 as expected_answer, while
   ask_user returns the option label C.

In an affected local database, notebook_entries.options_json contained:

{"A":"A","B":"B","C":"C","D":"D"}

The matching turn_events row still contained the complete descriptions in
the ask_user arguments. In two other affected entries, the stored expected
answers were Step 4 and Step 6, while the user's correct card response was
C; both were recorded as incorrect.

Steps to reproduce

1. Run DeepTutor with the Docker image and configure a model.
2. Create or open a Guided Learning / Mastery Path containing a memory or
   procedure knowledge point.
3. Continue until the tutor generates a multiple-choice question through
   mastery_quiz and presents it through ask_user.
4. Answer the interactive choice card.
5. Open Learning Space → Question Bank.
6. For turns where the model passed options: ["A", "B", "C", "D"] to
   mastery_quiz, observe that the Question Bank has lost the option bodies.
7. For turns where expected_answer is an option-body fragment instead of a
   label, select the correct label and observe that it can be graded wrong.

Expected behavior

• mastery_quiz.options should persist every complete option body.
• Bare label-only option arrays should be rejected and retried.
• Choice answers should be normalized to their stable labels before
  deterministic grading and Question Bank persistence.
• The Question Bank should always render the same option text shown on the
  original ask_user card.

Related module

Guided Learning

Configuration used

• Docker image: ghcr.io/hkuds/deeptutor:latest
• Guided Learning with an attached knowledge base
• Interactive questions presented through ask_user

Additional information

• DeepTutor Version: v1.4.12
• Operating System: macOS
• Container Python Version: 3.11.15
• Browser: Chrome
• Related Issues: Options do not render LaTeX formulas in quiz cards #587 is about LaTeX rendering and is not the same bug

Likely affected code:

• deeptutor/capabilities/mastery/tools.py
• deeptutor/capabilities/mastery/prompts/en/system.md
• deeptutor/capabilities/mastery/prompts/zh/system.md

A fix and regression tests are ready and will be submitted in a linked PR.