Module 9 practice · investigate before changing a component

Use the lesson and compare the separate solutions.

A. Reproduce the trace. Run methods.py failures. Identify the successful retrieval, the budget loss, the final template reason and the separate changed-source reason. Explain why this demonstrates neither a failed retriever nor neural prompt-injection resistance.

B. Classify four failures. For each, name the earliest relevant stage and a local synthetic check: an archived schedule appears; a six-word chunk omits a distant exception; a paraphrase returns no candidates; a complete packet produces a claim about laptops. Do not change production data or use a real learner account.

C. Propose a small counterfactual. Keep the renewal query and ranked IDs fixed. Describe the single change that tests the budget-loss hypothesis. What result would support the hypothesis, and what result would require a different explanation? Explain why adding more candidates alone is not a direct test.

D. Write a handoff. In at most six sentences, state what the local system implements, two observed failures, what has been tested and what remains unverified. Include the difference between a fingerprint check and source truth, and state that source instructions do not authorize account actions.

Self-review: stage-specific reasoning, unchanged unaffected components, exact executed mechanisms and a readiness statement that cannot be mistaken for a production or learner-pilot claim.