1. Batch write transactions in build_paper, start_attempt, save_answers,
and finalize (turned 75+ disk operations into 1 commit per action).
2. SQLite PRAGMAs: synchronous=NORMAL, cache_size=64MB, temp_store=MEMORY,
and mmap_size=256MB for zero-copy memory reads.
3. O(1) history: record right_count/wrong_count on attempts at finalize time;
history() loads in a single SELECT query without re-grading loops.
4. Native Rust load testing tool (src/bin/bench.rs) replacing Python scripts:
multi-threaded concurrent reads & simulated full student lifecycles with
sub-microsecond timing and statistical percentiles.
Sign-in page rewritten for non-technical students: Google-first when
configured, plain-language email path with honest 30-day scope, recovery
note, placeholders, full-width CTA. deploy/termux-start.sh sources .env
for GOOGLE_* credentials; deploy/env.example documents the 5-minute
Cloud Console setup; .gitignore covers secrets, DBs, pid/log files.
bench scripts send a browser UA so Cloudflare bot checks stop 403ing
local load tests. Landing bank counts cached 60s (five aggregate
subselects no longer run per hit). gzip compression on all responses.
The subscriber was pinned to DEBUG, so RUST_LOG=warn was ignored and sqlx
logged every statement to stderr in production. Now an EnvFilter defaults to
info with sqlx at warn; RUST_LOG=debug restores the query log.
Three benchmarks, so the hosting numbers come from measurement rather than
guesswork: scripts/bench.py for latency and throughput, bench_write.py for the
autosave and submit path under concurrent students, and bench_scale.py which
builds a database at the real bank's size (10,905 questions, 2,000 students,
12,000 papers, 900k answers) to report disk cost and query timings.
Two paths, one session. The GSI popup posts an ID token to /student/google;
where a popup is refused a PKCE authorization-code flow redeems server side at
/student/google/callback, keeping the client secret out of the browser.
ID tokens are verified here rather than trusted from the browser: RS256
signature against Google's published JWKS (cached an hour), audience pinned to
this client, issuer restricted to Google, expiry enforced, email must be
verified. State is single use and expires in ten minutes. Without
GOOGLE_CLIENT_ID the button is hidden and the email form is offered instead.
13 tests cover the verification rules using locally generated RSA keys,
including rejection of a foreign signature, a wrong audience, a wrong issuer,
an expired token and a rewritten payload. An example signs a token from an
untrusted key so the rejection path can be checked without a Google account.
Axum + SQLite full-stack copy of the ZenithPrep PYQ practice app.
Paper builder with unseen-question exclusion, timed CBT screen with
palette and autosave, +4/-1 grading with numerical tolerance, per-question
analysis, history, dashboard with weak-subtopic tracking and coach notes.
