Adds an optional roster.json (set of allowed student IDs) loaded at
startup. add_participant() raises StudentIdNotInRoster when the gate is
on and the supplied id is not present; route returns 403 with a clear
message and logs a roster_reject audit event. Names are NOT checked
against the roster: the join form asks for a current name as a soft
deterrent, but the only hard check is the id.
Includes a deploy/build_roster.py helper that turns class_register
attendance.xlsx into roster.json. Bootstrap env file now exports
QUIZ_ROSTER_PATH; missing file disables the gate (legacy behaviour).
Also drops the user-facing "The cookie is per-device." line from the
join card — students don't need to know the implementation; replaced
with "Enter your registered student ID and your current full name."
Three small UX/fairness tweaks from manual live testing:
1. Post-submit "wait for reveal" screen: show only the response time, no
score. The +score reveal leaked correctness — any positive number =
correct, zero = wrong — short-circuiting the "stop and think" beat
the reveal pause was supposed to enforce. Time stays as the
engagement signal; score now waits for the instructor reveal.
2. Final-screen "Correct X / Y" denominator is now total_questions
instead of questions_answered. Missed questions are scored zero, so
they belong in the denominator visibly. Server adds total_questions
to the session_ended payload.
3. Projector score-distribution: drop the in-chart count labels (they
collided with each other and with the median tag at small N), restore
the previously-computed-but-not-rendered x-axis tick labels at the
bottom. Stats line at the foot keeps n / mean / max.
Also: short-circuit the per-submit instructor + presence broadcasts
when no instructor / projector is connected (no listener, no DB work).
The 50-student load test was tight on margin against its 2 s
time_limit; with the new presence_message / live_histogram_message DB
queries firing on every submit, the margin disappeared on busy boxes.
Conftest fixture also bumped to 8 s per question for the same reason —
gives breathing room for sequential WS submits in the load test.
71/71 pytest green.
Both student-facing surfaces (the per-device join page and the
front-of-room projector) now render options as text only, no A/B/C/D
chips, no numeric prefixes. The letter-namespace remains internal:
canonical A..D in pool.json + submissions storage; canonical position
1..4 in the CSV export. Admin dashboard keeps letters because it is the
instructor's private console.
Why this lands now: the discussion of per-student option shuffling
flagged that A/B/C/D as discussion handles ("the answer is B") is itself
a leaky channel. Removing the labels closes that channel for the
non-shuffled case and keeps it closed if shuffling is added later.
Wire protocol: the submit message carries the option's full text
("answer": "Pipelining"). Server's submit_answer resolves text -> letter
via app.pool.resolve_option_key, which also accepts a canonical letter
so internal callers and tests stay readable. A non-matching string is
recorded as a zero-score submission with answer=NULL, locked in via the
PK + existing_submit_ack short-circuit. So an attempted UI bypass that
posts a fabricated string just produces a wrong answer; no retry.
CSV: A=1 .. D=2 .. C=3 .. D=4 in the answer column. Empty when no option
matched. Header unchanged so downstream pandas readers don't break, but
the value type is int instead of letter.
Histogram: the failsafe "submitted-but-no-match" row buckets into
"missed" alongside genuine misses — both yield zero credit and the
instructor cares about the same thing.
Tests:
- test_submit_accepts_option_text_resolves_to_canonical: production
wire format produces correct grading + canonical-letter storage.
- test_submit_failsafe_locks_in_zero_score_on_garbage_text: a non-
matching string is recorded at score=0 and a follow-up correct
submission cannot overwrite it.
71/71 green.
A multi-hour lecture has questions spread over the whole period; we can't
reasonably expect students to keep their devices focused for that long.
Blur events still get logged (no code change) so we have signal for
post-hoc analysis if the histogram is striking, but we don't promise it
as enforcement, and we don't make students self-monitor against an
unrealistic standard.
The portal's hijack-recovery flow has a non-obvious fairness property —
asking the instructor to reset your slot zeros every already-closed
question (status: missed) regardless of who triggered the reset. That
makes false-hijack claims strictly self-penalising and forecloses
"ask for a reset to retry Q1" as an attack on engagement scoring.
Surface this contract to students before they join: a native
<details>/<summary> accordion under the join form, styled with the
warn-tinted token palette, lays out the rules in plain language. No JS
required; keyboard- and SR-friendly.
tests/test_hijack_matrix.py: 11 end-to-end tests walking the
{hijack y/n} × {reset y/n} matrix:
- Cell A baseline (normal play)
- Cell B1 false-claim self-penalisation (full credit + partial credit)
- Cell B2 self-cleared cookie -> same penalty path
- Cell C hijacker without recovery holds the slot; audit accumulates
- Cell D hijack + recovery zeros closed Qs, kicks hijacker, normal next Q
- D-during-open-Q lets re-claimer use the remaining opened_at clock
- DELETE /admin/api/students/* requires admin auth (otherwise the
recovery hatch becomes a hijacker tool)
- Repeated 409 attempts each accrue duplicate_join audit rows
- Stale post-recovery cookie cannot pollute the audit log
- Strict non-increase: even an instant-correct (1.00) is zeroed on reset
69/69 pytest green.
Refinement pass on top of the validated v1.2 base.
Hardening / quick fixes
- Caddyfile.tpl: CSP / HSTS / X-Frame / Referrer-Policy / Permissions-Policy,
1 MiB request body cap, X-Forwarded-For pass-through; stock-Caddy compatible.
- auth.py: STUDENT_MAX_AGE 1y -> 30d.
- bootstrap.sh: stage 5 prepends `git config --add safe.directory` so the
re-bootstrap path no longer 'detected dubious ownership' faults.
- admin.js: drop the misleading `closedPayload?.state || session.state`
shim; state derives from session only.
Anti-cheat
- New `student_events` audit table; new POST /api/session/{sid}/event for
blur / visibility_hidden / focus / visibility_visible. quiz.js debounces
events at 1.5s and uses sendBeacon for visibility_hidden so the event
survives a navigation. Counts surface in admin presence + CSV export.
- First-claim-wins on join: add_participant raises DuplicateStudentId on
PK violation; route returns 409 + records a duplicate_join audit event
with attempted name + IP + UA. Admin dashboard surfaces a per-row red
badge for hits on real participants and a top-of-page alert for orphan
attempts.
- DELETE /admin/api/students/{id} as the recovery hatch: clears the
participant + submissions, kicks active WS sockets so a stale cookie
cannot continue submitting. quiz.js surfaces the FastAPI detail message
in the join form so users see the 'already in use' guidance.
Presence panel
- New presence_update WS message; in-process presence map keyed on
student_id tracks ws_count + last_seen_ms. Admin dashboard renders
per-student rows: connected/idle/dropped dot, blur+hidden+duplicate
badges, 'answered current Q' tick, and a clear-student button.
Projector view (public, read-only)
- /projector/?sid=..., GET /api/session/{sid}/projector, WS
/ws/projector/{sid}. Single self-contained projector_state snapshot
pushed on every state change. Public leaderboard strips student_id;
QR rendered server-side as data: URL (CSP-compliant).
- Includes per-Q answer histogram, 8-bucket response-time distribution,
10-bucket score distribution.
- static/projector.{html,css,js}: editorial-broadside design — masthead,
registration crosses, conic-gradient countdown ring, SVG stepped-area
score distribution with median tick, leaderboard row-stagger. Inherits
light/dark tokens from style.css; honours prefers-reduced-motion. No
scroll at 1366x768 / 1920x1080 / 3440x1440.
Tests
- tests/test_anti_cheat.py: blur logging + CSV count, unknown-kind 422,
unauthenticated event 401, duplicate-join 409 + audit, admin
clear-student happy + 404, server-side submit lockout regression.
- tests/test_projector.py: snapshot shape, leaderboard student_id
redaction, WS push on state change, 404 for unknown sid, page redirect
when no sid.
- Existing tests updated for the new presence_update snapshot frame +
CSV header columns + first-claim-wins refusal of re-key.
57/57 pytest green; smoke-tested locally end-to-end.
Replace the manual "Disconnected → Reconnect button" screen with a small
top-banner that retries the WS up to 8 times (500ms → 5s, ~27s budget).
On open, snapshot replay restores the question card and countdown so a
brief network blip is invisible to the student. After the retry budget
exhausts, fall back to a manual "Reload" card.
Same path covers initial WS-open failures (transient TLS hiccups on the
Aliyun edge), since the first connect() and subsequent reconnects share
the schedule. Auth-related closes (1008) still hard-reload immediately
so an invalidated cookie lands on the join form, not in a retry loop.
Submits are now also gated on ws.readyState === OPEN; clicks during a
reconnect are silent no-ops, and the question re-renders fresh once the
server replays state.
Per-question score is now a float in [0.0, 1.0] snapped to a 21-level
0.05 grid, replacing the previous 0-1000 integer scale. Easier to read
on a leaderboard, ties become acceptable rather than vanishingly rare,
and small clock-skew differences no longer split rankings.
DB schema: score is REAL now (SQLite type affinity is loose enough that
existing rows still read fine, but new inserts go in as floats).
Frontend: added fmtScore() helpers in admin.js and quiz.js to render
two decimal places consistently (0.85, 1.20, 5.00) so float-arithmetic
sums never display as 0.8500000000000001.
Tests: linear_decay/flat/exponential_decay assertions updated; added
a snap-to-grid invariant test.
Three coupled fixes from the first manual test pass:
1. Stale signed cookie no longer 500s. `rooms.me()` now raises KeyError
when the participant row is gone (the previous code deref'd None and
threw TypeError, caught by quiz.js's catch-all as 'link expired').
`/api/session/{sid}/me` translates KeyError into 401 + delete_cookie,
so the client falls back to the join form cleanly.
Returning a JSONResponse directly because `raise HTTPException`
discards Response.delete_cookie mutations (FastAPI middleware
composes a fresh response on exception).
2. Reset is now a soft restart from the student's perspective. Before
closing each student WS in `RoomManager.reset`, the server now sends
a `{"type": "session_reset"}` message. The student SPA tears down
local state and re-runs boot(); /me returns 401 (now that the
participant is gone) and the join form renders without the user
having to manually reload. The WS close handler suppresses its
"Disconnected" screen during a reset to avoid a flash.
3. "You" highlight on the student leaderboard is now matched by id, not
by name. `RoomManager.leaderboard()` accepts an optional
`you_student_id` and stamps `is_you: true` on the matching entry only.
No other students' ids leak over the wire (we still don't include
`student_id` in the public top5 payload). quiz.js's renderBoard
prefers `r.is_you` when any row is marked, falling back to name match
for backward compatibility.
41/41 tests pass. Two new tests cover (a) the 401 + cookie-clear path
after reset and (b) `is_you` marking only the requesting student.
Targeted fixes on top of the editorial-lecture-hall pass:
- Leaderboard rank columns now align across all rows; medal stripes
reserve their 3px width on every row (no more 6px shift between
podium and chasers). Silver bumps to higher-contrast values in both
light and dark modes.
- Student leaderboard gains a visible "you" highlight (blue stripe,
blue name + score, small "you" eyebrow under the name). Matches by
display name since the server's student-facing top5 doesn't include
student_id.
- Lobby and Finished states share an editorial state-cta treatment:
display-serif "Ready to start." / "That's a wrap." with a numeric
cta-stats strip that anchors the right column on a projector.
- "02 PRE-FLIGHT" eyebrow continues the "01 JOIN" sequence on the
side panel, giving the page a magazine-spread rhythm.
- Live distribution suppresses empty bars when zero submissions and
shows a calm italic "Bars appear once the first answer comes in."
line instead.
- Roster orders newest-first; the top three rows light their dot
green and the freshest row gets a soft pulsing halo, so the
operator sees the room filling up at a glance.
- Student reveal "Your pick" tag moves to a top-edge ribbon above the
option text so it stops colliding with the count column on phones.
Editorial-lecture-hall direction: Source Serif 4 for question prose
and headlines, IBM Plex Sans chrome, IBM Plex Mono for tabular numerics
(countdown, scores, rank, session id, join URL). Single ink-blue accent
in light mode, brass-amber in dark mode; warm paper background instead
of the soft grey wash. Dropped border-radius from soft 14px to a sharp
2-4px to read as printed material rather than consumer app.
Density rebalanced for the two viewing surfaces. Student question text
goes to clamp(1.5rem, 2.4vw, 1.95rem) so it dominates a 390px phone;
admin chrome (Q-num, countdown, hist labels) tightened so the projector
read is "QUESTION LIVE" + question + options + distribution at a glance
across a 1920x1080 lecture hall. State badge is uppercase + tracked
with a status dot; live state pulses, urgent countdown (<=10s) blinks.
Leaderboard becomes a tabular scoreboard: hairline borders, alternating
row tint, gold/silver/bronze left-border medals on top 3 only (no other
rank treatments), mono numerics throughout. QR panel now has its own
SCAN TO JOIN eyebrow, the URL row sits below in mono with a copy CTA,
session id rendered as a code chip, anchored as one shareable artifact.
Picked-answer button gets a 2-step settle (scale 0.97 -> 1, color
swap), correct-row reveal animates an inset border-draw, countdown bar
gets a slow breathing highlight overlay; all motion respects
prefers-reduced-motion. JS change is one line per SPA: toggle .urgent
on the countdown when remaining <= 10s.
Backend simplification:
- The server now loads ONE pool JSON from $QUIZ_POOL_PATH at startup and
upserts a single canonical session. The session id comes from the pool
JSON's optional "session_id" field, falling back to $QUIZ_SESSION_ID.
- The multi-quiz / multi-session CRUD API is gone:
DELETED GET/POST /admin/api/quizzes
DELETED POST /admin/api/quizzes/upload
DELETED GET/POST /admin/api/sessions
DELETED GET /admin/login (HTML stub)
DELETED GET /admin/api/sessions/{sid}/csv (replaced by /admin/api/csv)
Replaced with a single-session control surface:
GET /admin/ — serves admin.html unconditionally
GET /admin/api/state — admin-gated; pool meta + state + QR + join URL
POST /admin/api/reset — admin-gated; wipe submissions + back to lobby
POST /admin/logout — clear admin cookie
GET /admin/api/csv — single-session results
WS /ws/instructor/{sid} — kept; new commands "next" + "reset"
- Instructor "Next" button is now a single state-driving command
(RoomManager.advance_to_next): from lobby it opens Q0; from question_open
it closes the current Q and opens the next; from question_closed it
opens the next; if past the last question it ends the session.
- New RoomManager.reset wipes submissions, participants, and per-question
state, then broadcasts a clean lobby.
- Student GET / now redirects to /?sid=<canonical> when no sid is given,
so the QR / share URL is fully deterministic.
Frontend rewrite (functional baseline; visual polish to follow):
- /admin/ is now a single SPA: GET /admin/api/state decides login form
vs dashboard. No separate /admin/login URL bar.
- Admin dashboard is state-driven with one primary action per state.
QR code, join URL, and live participant list are always visible on the
left so the operator can leave the page on a projector.
- Student answer buttons are big and tappable; reveal screen highlights
correct/wrong choice + shows score, total, and rank.
- Static admin/student SPAs share a CSS palette with light/dark support.
Tests rewritten around the single canonical session id.
The auto-bootstrapped session lets each test fixture skip the old
quiz/session creation dance. 39/39 tests pass.
Cleanup:
- Deleted CODEX_PROMPT.md, IMPLEMENTATION_REPORT.md, NOTES.md, SPEC.md,
static/observer.html (obsolete codex-build artifacts and the unused
observer view).
- .gitignore now blocks /pool.json (the runtime file the operator drops
on the server) and the leftover .codex_done / codex_run.log / etc.
- bootstrap.sh seeds /opt/quiz/pool.json from examples/pool_example.json
on first deploy so a fresh box reaches a usable state without manual
intervention; .env now includes QUIZ_POOL_PATH.
