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.
Exam/solution pages print clean via browser print-to-PDF: interactive
chrome hidden, questions unhidden, ink-friendly colors. Options printed
as black bars without the surface override — .opt/.chk/inputs/palette
now forced white. Verified with print-media emulation screenshot.
coach_notes takes the tag rollup the dashboard already fetches: a
dominant mistake type (>=half of >=2 tags) yields a targeted fix, and
chronic wrong-over-blank across history yields a guessing warning. Same
Vec<String> output, no view changes. Three unit tests cover fire/quiet
paths.
Sessions never expired server-side despite the 30-day cookie Max-Age;
repeat sign-ins orphaned rows. user_id now rejects tokens older than 30
days and deletes them on sight. Verified live: fresh 200, backdated 302
with row removed.
The exam screen autosaves on every answer; a stuck client retrying in a
tight loop could hammer SQLite's single writer. Ctx carries a small
in-memory per-user windowed counter with opportunistic cleanup — no
Redis needed. Verified live: 30x200 then 429s.
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.
GET /paper/:id redirects the owning user to their attempt screen (404
otherwise, login wall otherwise). Shared /s/:token pages now end in a
real action instead of a dead list: signed visitors get a take-this-paper
button, anonymous visitors get a sign-in link preserving the share URL
as next. Verified live: 1/302/1 across the three states.
seen_questions gains seen_at (with ALTER TABLE migration for existing
DBs, index created after the migrate step). Submit stamps seen_at with
an upsert so repeats refresh recency. build_paper tops up short
unseen-only pools from longest-ago-seen in scope instead of erroring.
Verified live: 1-question subtopic served the same seen question on
repeat builds (303, not 400).
Result page shows a why-lost row (concept gap / calculation slip /
misread / out of time / blind guess) on every wrong or blank question.
POST /result/:attempt/tag/:qid toggles one tag; ownership checked,
vocabulary enforced server-side. Dashboard gains a 'why you lose marks'
section aggregating tags across all submitted attempts. Verified live:
tag persists, rollup renders.
load_chapter_blocks used a correlated COUNT subquery per chapter row:
~5s on the 9.8k-question bank. Rewritten as one GROUP BY joined once
(16ms p50 on /build). Nine CREATE INDEX statements added to init_db
so fresh and existing DBs both get them. build_paper had a dead
placeholder branch issuing a subtopic_id=0 lookup per chapter; removed.
scripts/import_examgoal.py pulls the MIT-licensed examgoal-derived
14,973-question pickle and keeps the 9,813 fully-text MCQs with single
correct answers (2002-2025, all subjects). chapterGroup becomes our
chapter, chapter slug becomes our subtopic. Idempotent: skips stems
already present.
views.rs gains rich() — a read-side sanitizer matching the importer's
allowlist — and all six stem/option/solution render sites use it.
KaTeX auto-render (trust:false) added to head() for $$..$$ math.
db.rs gains nine CREATE INDEX statements; the chapter loader query
drops from ~5s to 6ms on the 9.8k-question bank. DATA.md rewritten
around the real pipeline with attribution.
The builder previously exposed only chapters. Now each chapter expands to show
its subtopics as individual checkboxes: selecting a chapter checks all of its
subtopics, selecting the subject-level box checks everything, and selecting
individual subtopics sets the chapter to indeterminate. The exam query filters
by subtopic_id when any are given; the SQL path deduplicates so a question
matching two subtopics only appears once.
JEE mode sets duration to 60 × unique-subject-count (180 min for a full paper).
On the exam screen this renders per-subject countdown strips: Physics 60:00,
Maths 60:00, Chemistry 60:00. Each strip counts down independently; when one
hits zero the screen auto-jumps to the first unanswered question of the next
subject. The last strip exhausting time submits the form.
Single-subject papers keep the flat timer and show no strips.
Also: all audit targets now genuinely 44px (the .opt labels were 42px).
The screen had no mobile state at all: the clock scrolled away mid-paper, the
only navigation was save-and-next so a candidate could not go back, the palette
sat below the question where it pushed submit off-screen, and the nav row lost
three of its four links under 700px.
Sticky header carries the clock and a progress bar; previous/next are real
buttons; the palette is a drawer below 1024px opened by a floating button that
sits above the tab bar. Primary destinations move to a bottom tab bar on
phones, data tables scroll inside their own card, and every control meets the
44px touch minimum.
Verified with a headless browser across five viewports rather than by reading
the stylesheet: scripts/audit_mobile.py fails on horizontal overflow, tap
targets under 44px, and content hidden behind a fixed bar; scripts/shots.py
captures each page at both widths. Both caught bugs I would otherwise have
shipped, including a palette toggle that lived inside the drawer it opened and
so could never be pressed on a phone.
fmt_dur drops a leading zero hour, so a 24 minute paper reads 24m 00s.
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.
