Investigate shared homework scoring consolidation without behavior changes

[alexeygrigorev]

Retire duplicate homework answer checks using the pinned shared package

Status: blocked; isolated candidate frozen and uncommitted
Tags: courses, enhancement, P1
Depends on: #438 development deployment recovery through #440 (operational hold). #438 code is merged at f143a19b7d5ef7b713c7b8139d01619f333961b6; the accepted source is the implementation base, but the failed development deploy remains unresolved.
Blocks: —

Reporter context

The owner wants DTC, AISL, and community-base course code simplified without changing any feature or visible UX. The retirement inventory named DTC homework checking and scoring as a candidate, but a candidate is not approval to replace scoring orchestration or to bypass the larger cohort adoption in #55.

Normative references

• _docs/specs/04-courses-and-cohorts.md, especially the preserved homework/question/answer/scoring contract and its characterization requirement.
• _docs/specs/07-security-privacy-operations.md for bounded answer failures and redaction.
• _docs/architecture/app-boundaries.md and AGENTS.md for one domain owner and no legacy runtime shim.
• _docs/ci/change-selective-ci.md and _docs/specs/10-verification-strategy.md for versioned verification.
• community-base v0.5.10, community_base.coursework.answer_checks, the public owner already in DTC's pin.
• docs/plan/evidence/code-retirement-inventory-2026-09-29.md, ranked bundle 8.

Scope

With #438 merged at f143a19b7d5ef7b713c7b8139d01619f333961b6 as the implementation base, remove the duplicate courses/homework_answer_checks.py module and retarget its production and test imports directly to community_base.coursework.answer_checks. Production importers are courses/homework_score_calculation.py (is_answer_correct) and courses/views/homework_answers.py (is_free_form_answer_correct); verify the complete caller set on the implementation revision, including all Python import forms, aliases, tests, patch targets, and dynamic strings. Do not leave a compatibility facade or copy the checks into another site file.

The v0.5.10 shared module has the same answer and question type values and checking rules as the site duplicate. Its Question and Answer annotations do not enforce model identity at runtime; its checks use the existing DTC question/answer attributes and methods. DTC already installs community_base.coursework. Characterize this interoperability on actual DTC model instances before deleting the duplicate. Preserve the exact HomeworkAnswerCryptoError identity established by #438 and the current Question.get_correct_answer() resolution and configuration path.

Keep courses/homework_score_calculation.py as DTC's scoring owner. Its FAQ and learning-in-public components, persistence, observability, invalidation and transaction behavior are outside this slice. Retargeting its answer-check import does not adopt package scoring.py. Report actual net application lines deleted separately from changed test imports; the 145-line site check module is a gross candidate, not a promised net reduction.

Behavior to preserve

• ANY answer handling, free-form trimming, case-insensitive exact and contains checks, integer parsing, and the existing 0.01 default float tolerance.
• Multiple-choice and checkbox answer indexing, comma splitting, blank answers, malformed numeric input behavior, and unknown answer/question type behavior.
• The precise crypto failure boundary: is_answer_correct converts HomeworkAnswerCryptoError to False, while other exceptions keep their existing behavior. Never reveal source answers, key material or ciphertext in errors or logs.
• Existing configured keyring lookup, source answer resolution, stored envelopes, scores, answer correctness fields, rendered feedback, routes and permissions.

Non-goals and dependency boundary

• No package pin bump, package change, model/schema migration, stored-data rewrite, template/view behavior change, API addition, or new UI.
• No replacement of courses/homework_score_calculation.py or homework batch scoring with package scoring. Preserve cohort homework, answer, submission, scoring, and statistics behavior #55 remains the dependency-blocked domain adoption owner for that larger transition; this issue does not satisfy or bypass its prerequisites Migrate edition-like Course records to reusable Course → Cohort #51, Replace global course staff access and plaintext API tokens with scoped capabilities #52, Add Course/Cohort lifecycle, public routes, and complete cohort duplication #53 and Preserve cohort learner preferences, progress, dashboard, and calendar behavior #244.
• Consolidate homework answer encryption on the shared package #438 code is merged at f143a19b7d5ef7b713c7b8139d01619f333961b6, but its development deployment failed. Add a guarded development website schema rebuild and redeploy #440 owns the bounded recovery. Keep this candidate frozen and uncommitted until that operational hold clears. Do not edit or reuse Consolidate homework answer encryption on the shared package #438's frozen verification worktree. Its shared crypto exception identity is part of this contract.
• Keep the shared DTC main and other agents' work untouched. Use an isolated issue worktree; no merge, push or PR during review.

Acceptance criteria

• A pre-deletion and final-revision caller inventory covers direct, parent-package and dotted imports, aliases and attributes, tests, scripts, patch targets and dynamic references; no use of the deleted site module remains.
• courses/homework_answer_checks.py is deleted and every caller uses the v0.5.10 public package owner directly, with no facade or second implementation; actual net application lines deleted are reported separately from test changes.
• Shared checks operate on DTC Question and Answer instances with the same AnswerTypes and QuestionTypes values, answer resolution/configuration, and exact shared crypto exception identity established by Consolidate homework answer encryption on the shared package #438.
• Existing tests characterize and preserve correct/incorrect ANY, exact, contains, float, integer, multiple-choice, checkbox, blank, malformed and unknown-type outcomes, including score values and safe crypto failure. Add a focused behavior test before deletion only for a material uncovered boundary.
• DTC FAQ and learning-in-public score components, persistence, observability, invalidation, scoring errors, timestamps and grading UX remain unchanged; no package scoring orchestration is adopted.
• No package pin, model, migration, template, route, API, permission, stored answer or visible page change occurs.
• Focused answer-check, answer-resolution, crypto, homework-scoring and rendered-answer tests pass before and after. uv run --frozen python scripts/ci.py lint and the versioned _docs/ci/change-selective-ci.md verification plan, run, evidence-check and report-check pass; execute the graph-selected scripts/ci.py quality contract (including verification-quality when required by the plan) with exact base/head, graph and plan digests and every component disposition recorded by Engineer and independent Tester. Use the graph-selected backend browser tier; any fallback follows the plan.
• Independent Tester verifies the uncommitted isolated diff, including a repository-wide import check and screenshot evidence classified as not_applicable only if the graph confirms no render impact. PM accepts afterward. No commit, merge, push or PR occurs before the approved handoff.

Browser regression scenario

Learner submits and reviews graded homework

Given an enrolled learner has an existing homework containing free-form and choice questions, including a source-managed encrypted correct answer,
when the learner submits answers and later views the scored homework,
then answer correctness, question/FAQ/learning-in-public components, total score, feedback and safe answer visibility match the current site. The backend ownership change introduces no new page or browser behavior.

Repository and operations scenarios

• An answer whose stored encrypted source value cannot be resolved produces the same safe false correctness result through the shared crypto exception class.
• A malformed numeric choice retains the existing failure boundary; the refactor does not silently turn it into an incorrect-answer result.

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Blocked by: #438 development deployment failure; #440 owns recovery. The #439 isolated candidate remains frozen, uncommitted, unmerged and unpushed pending that result.

[alexeygrigorev]

Grooming Complete

Scope: retire the 145-line DTC answer-check duplicate by importing the public community_base.coursework.answer_checks owner already shipped in pinned v0.5.10. Keep DTC's 78-line scoring orchestrator and its persistence, score components, errors, observability and cache behavior. The shared checks use the same enum values and duck-typed question/answer methods; the engineer must prove parity on DTC instances and run the named before/after checks.

Dependency: implementation waits for #438's accepted local commit. #438 currently changes the checks module's crypto import, and its shared exception identity is part of this contract. The larger model/scoring adoption #55 remains independently blocked on its own prerequisites and is not bypassed here.

This was read-only grooming. No DTC source or frozen #438 worktree was changed, and no tests were run for #439.

[alexeygrigorev]

Grooming Update

#438 is now closed and merged in f143a19b7d5ef7b713c7b8139d01619f333961b6. #439 is ready for an isolated implementation worktree based on that commit or a descendant; its former implementation dependency is satisfied. The frozen #438 worktree remains outside this issue's ownership.

I also corrected the verification language to use the maintained uv run --frozen python scripts/ci.py lint and versioned verification plan/run/evidence/report contract. The graph-selected quality components remain required, including verification-quality when selected. This changes no source scope or acceptance behavior, and no site files or tests were touched in grooming.

[alexeygrigorev]

Prerequisite reopened after deployment failure

#438 is reopened: CI passed for f143a19b7d5ef7b713c7b8139d01619f333961b6, but its development deployment failed during schema migration before services changed. The dedicated on-call is investigating the development task logs.

#439 is therefore held behind its existing dependency. The isolated candidate has removed the 145-line duplicate and passed focused before/after checks, but is frozen with no full verification run, commit, merge, or push. Work resumes after #438 is resolved; no grading or UI change is authorized by this hold.