There will be no courses. What was there: one draft called "jk" with two empty
lessons, and 4,000 lines of code around it — courses, modules, lessons,
enrolments, per-lesson progress, SCORM, BigBlueButton, completion certificates,
three React pages, a router, two models.
Its real cost was everywhere else. Every query that measured practice had to
remember `Quiz.course_id.is_(None)`, and forgetting it in one place would have
silently mixed course attempts into a learner's analytics; the bank predicate
carried a subquery to exclude a course's own questions from every search,
recommendation and share; quiz access had a second, parallel rule about
enrolment. All of that is gone, so the remaining rules say what they mean.
`quizzes.allow_review` goes with it. It was only ever enforced for a course
quiz, so it had become a promise nothing keeps — the public session page was
still offering "no answer review" about sessions that review fine.
The fixtures' question 5 lived in a course quiz and stood for "a question that
exists but is not in your bank". There is no such thing now — a question is in
the bank unless it is deleted — so the counts it kept out of the numbers are
back in, and the tests that turned on it now turn on deletion or on the
attempt that actually holds a question.
Files the LMS uploaded stay on disk and stay protected: LEGACY_LMS_PREFIXES in
app/utils/upload_access.py is what keeps them unreachable.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TqXevQJhxFrM7jJg82cgZN
`Question.is_shared` defaulted to 1 and was only ever set by a route nothing
called, so in practice it divided the bank into "everything" and "everything,
plus your own private ones" — a distinction that cost every recommendation
denominator a join and never changed an answer. Who may reach the bank is the
site's own access rules; who may manage a question is the category grant tree.
So the two predicates the whole bank was built on are now the same thing, and
say what they actually mean: a question is out of reach if it has been deleted
or belongs to a course. Nothing else. The column is dropped, the route that set
it is gone, the bulk "share" action with it, and the Private tile and pill go
from the question manager.
The tests that turned on it have been rewritten rather than deleted, because
the rule they were really about survives: revoking a question still revokes
every session carrying it — by deleting it, which is the only revocation left.
Several others named a category holding exactly two reachable questions and
then answered two particular ids; that category holds four now, so they name
the pair instead. A session's own sharing flag is untouched — that is a
different thing, and it is still how a session is handed to somebody.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TqXevQJhxFrM7jJg82cgZN
Images were findable only by the filename someone typed. `media_assets` gives
them a title, caption, alt text, a category on the shared tree and tags, with a
weighted tsvector so they are searchable now (migration y7e8f9a0b1c2).
The embedding column is filled from the caption today. A vision-capable model can
fill it from the image itself later without another migration — and because
`embedding_model` stamps every vector, a text-embedded caption and a
vision-embedded image stay distinguishable instead of being silently mixed in one
index. Adding "media" to the embeddable kinds is all the retry task, the full
regeneration and the health report needed.
`media_tag_links.tag_id` carries no ORM-level foreign key: `question_tags` is
created by raw DDL rather than a model, so the constraint lives in the migration
where the table actually exists.
Tests: 113 backend green.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PpfzbZ1QTLMeVYxM2kyq8m
Search
- Retrieval was hybrid in name only: the keyword filter was applied to the SQL
query, so results were the *intersection* of the two rankers. A question that
matched the meaning but not the literal string could never be returned. It is
now a union, fused with Reciprocal Rank Fusion (a text rank and a cosine
distance are not on comparable scales, so RRF uses only their orderings).
- Added a generated `search_vector` tsvector + GIN index, so the lexical half is
ranked full text rather than ILIKE substring matching.
- Chose Postgres + pgvector over OpenSearch/Elasticsearch: a search cluster
would add a second datastore to keep in sync and a JVM on this host, to
replace an index Postgres maintains inside the same transaction.
- Removed the keyword-only mode. It looks precise but silently drops the
question that asks the same thing in different words.
Embeddings — measured on 500 real questions, using each question's own
explanation as a paraphrase query (known answer, no hand labelling):
bge-small (local CPU, 384d) R@1 0.840 R@5 0.953 186ms/query
bge-m3 (LiteLLM proxy, 1024d) R@1 0.847 R@5 0.973 93ms/query
BGE-M3 wins on both quality and latency and needs no extra credential, since
llm.danvics.com already serves `openrouter-bge-m3`.
Three gaps this exposed, all fixed:
- Nothing recorded which model produced a stored vector, so changing models
silently mixed incomparable spaces. `embedding_model` / `embedded_at` now
stamp every vector, `GET /admin/embedding/health` reports current vs stale vs
missing, and regeneration defaults to stale-only.
- The generator read the model from env while the stamp read a Redis override,
so a vector could be labelled with a model that did not produce it. Both now
resolve through one function, with a regression test.
- Embedding at creation is best effort, and a failure left a question invisible
to semantic search forever. `retry_missing_embeddings` runs every 15 minutes
via Celery beat and backfills missing or stale rows.
- Query embeddings are cached in Redis per model, so typing is not a network
round-trip per keystroke.
`dimensions` is only sent to OpenAI's embedding-3 family; BGE-M3 rejects it.
Tests: 8 new backend tests (union not intersection, fusion ordering, per-ranker
failure degradation, provenance stamping, stale/missing accounting, generator
and stamp agreement). Full suites green: 95 backend, 127 frontend, build clean.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014yhHB8Pc7oQqyqn2Vo9DXA
