The bug: answering a quiz and navigating away mid-turn, then returning,
re-prompted the same question. Root causes: (1) the answer was durable only
at onFinish — every mid-turn view read the stale pre-answer record;
(2) the server had no notion of a turn in flight; (3) remount treated the
stale record as current, with no re-attach path. Worse, the stale dock let
the quiz be answered again, racing two turns into a last-writer-wins
saveMessages clobber.
Fix (four pieces):
- Write-ahead persist in chat-handler: the request body IS the client's
canonical state — saved to disk BEFORE the stream starts. The answer is
durable the instant the request arrives; crashes recover via the existing
mount continuation.
- Turn liveness registry (src/server/turn-liveness.ts): in-memory chatId →
in-flight map with a TTL leak guard; beginTurn rejects concurrent turns
(409) so one turn ever owns a chat. endTurn runs in onFinish AFTER
persistTurn, so pollers that see not-in-flight always read a finished
record; a turn-start failure clears the registry (no lockout).
- GET /api/chats/[id] reports turnInFlight; the chat page passes
initiallyInFlight to the client.
- Client re-attach (components/chat.tsx): while in flight, busy shimmer +
composer gated + mount continuation suppressed; poll /api/chats/[id] until
the turn finishes, then syncFromServer adopts the completed transcript.
Stop stays local-stream only (a server turn has no client request to
abort).
Verified by scripted-model tests: concurrent turn 409 + registry lifecycle,
write-ahead durability mid-turn, failed-turn lockout guard.
quizInputSchema now enforces (via pure quizInputProblems + superRefine) that
correctAnswer resolves against option values, options are non-empty and
unique, and multi-answer requires multiSelect — schema-valid now implies
gradeable. The AI SDK already returns invalid tool input to the model as a
tool-error part (verified in ai@7 run loop), so the teacher retries in the
same turn. chat-handler onError passes tool-input validation messages
through to the client (masked 'An error occurred.' for everything else).
Covers the Gate 3 GLM failure: correctAnswer slug matching no option.
Per-entity semantic ports (src/core/ports.ts), one adapter family
(src/store/*, fs JSON/JSONL), exactly one composition point
(src/server/stores.ts). Dependency direction is now machine-checked:
adapters implement core interfaces; core never imports an adapter.
The inversion:
- core/graph.ts (emitChat/getGraph/graphSnapshot/foldStaleChats) is now
pure — it takes the storage ports as explicit parameters (GraphDeps).
No store imports; newGraphNodeId is local; node id format unchanged.
- core/graph-context.ts buildGraphContext() no longer defaults to the
live ledgers: the chat-handler hands in getGraph(graphStore) per turn.
- store adapters export exactly one object each implementing their port
(chatStore/graphStore/jobStore); bodies otherwise verbatim.
NodeMapping + SessionCheckpoint moved store/graph -> core/contracts
(they ARE contract shapes); CreateJobInit/JobPatch live in ports.
- titleFromPrompt moved store/chats -> core/contracts (pure helper,
planNodeStatus precedent). Store modules now contain persistence only.
- server/stores.ts is the composition root; server/{chats,graph,jobs}.ts
and chat-handler wire from it; agent (plan tools, sub-agent runner)
call the port objects. The shell surface (@/src/server exports) is
unchanged.
Lint law extended: the whole of src/core is now a purity zone (was a
file glob with a graph/graph-context exemption). Verified it fires on
core->store imports; tsc clean, 190/190 tests, eslint clean, prod build
clean (prerender 6/6). Tests pass deps explicitly — graph.test uses the
same fs-adapter pair stores.ts wires in production; graph-context.test
keeps its in-memory ledgers as a GraphStore implementation.
- Animation: the blob's shell morphs height (WAAPI, 180ms) on every
variant change — chat ↔ question ↔ collapsed bar — plus a quick
fade/rise (160ms) on the swapped content. Gotcha pinned in code: never
measure the shell while a morph is in flight (getBoundingClientRect
reads the ANIMATED value and corrupts the next morph's start height);
cancel running morphs before measuring, refresh settled height only
when no morph is running.
- Gradient-over-scrollbar fixed structurally: the dock is no longer an
absolute overlay on the conversation root — it's sticky bottom-0 INSIDE
the scroller (in flow). The transcript scrolls fully clear of the dock,
the fade never touches the scrollbar lane, and the pb-hack clearances
are gone.
- New question while at the bottom scrolls to reveal the dock; scrolled
up → collapsed bar, no yank.
- Thin dark native scrollbar app-wide (8px webkit + scrollbar-width:thin,
dark thumb, transparent track). Note: use-stick-to-bottom sets
scrollbar-gutter: stable both-edges on its scroller — the lane is
outside the content flow by design.
- 'Writing a question…' transcript shimmer while a tool call streams its
input (same slot as 'Thinking…'). Protocol pinned by a test asserting
tool-input-start precedes tool-input-available; scripted mock now
streams tool input as deltas like real providers do. (OpenRouter/
Anthropic often delivers the whole input in ONE delta — then the dock
appears instantly and no indicator is needed or shown.)
Verified live: grow 54→349px and shrink 349→54px fire with correct
from/to; collapse/expand intact; gradient stops before the gutter;
Thinking… observed in-page; 58/58 tests.
Sidebar (replaces the modal drawer):
- Inline, toggleable, no backdrop/focus theft — can stay open while working
- Open state persists across pages (provider in root layout) and reloads
(localStorage; starts closed server-side to avoid hydration mismatch,
stored value applied post-mount; default open on first run)
- Hamburger in page headers only when closed; close button in sidebar header
Floating composer blob (per reference screenshot):
- Floats over the transcript (absolute overlay), persists at bottom while
scrolling, content fades behind it (gradient mask); pb-44 scroll clearance
- Concentric corner radii: blob rounded-2xl(16px) − p-1.5(6px) = send
rounded-[10px] = 25% of the 40px button; CornerDownLeft icon per reference
- Stop moved from header into the blob (busy → square icon)
- prompt-input.tsx + 7 orphan ui files pruned (attachments/command palette
unused); hand-rolled Composer is ~100 lines and render-tested
Pending-question morph (one text field on screen, never two):
- Quiz/ask-select pending → blob becomes the note field (send hidden, hint
line above); card's internal note input removed; Submit consumes it
- Ask free-text pending → blob becomes the answer field; its send submits
via the card's registered submit api (ref bridge); Enter works
- Chat owns the single text state; card clears it on submit
- canSend for answer mode mirrors the card predicate directly — reading the
ref during render lagged one commit (found in browser testing)
Widths: one shared column (max-w-3xl + px-4) for transcript, cards, and
composer — all three measured pixel-identical (left 416, width 736).
Assistant Message max-w-full/MessageContent w-full (was max-w-[95%]/w-fit —
the 'cards are a bit shorter' bug).
User messages render plain text again — no math pipeline on learner-authored
text (currency hazard accepted for the model only, guarded by the prompt).
Tests: 58 pass (5 new composer pins; card tests updated to controlled
props). Verified live: note flow, answer flow, sidebar persistence, float,
fade, zero console errors — plus the live model spontaneously honoring the
$ currency escape contract in a continuation.
The teaching agent no longer runs on pi. Stack:
- ToolLoopAgent (ai@7) + OpenRouter (OPENROUTER_API_KEY), model via LH_MODEL,
default anthropic/claude-sonnet-4.5 with reasoning tokens
- quiz/ask_user_question = client-side tools (no server execute): the call
lands as a typed tool part in input-available state; the card grades via
src/core/question-core.ts; addToolOutput sends the verdict; the teacher's
reaction continues the same assistant message
- resume-mid-quiz is free: the pending tool part persists in the transcript
- persistence: one JSON per chat (data/chats/), full UIMessage transcripts,
saved onFinish (also on abort)
- UI: AI Elements (owned copy-paste components, pruned to the five in use)
+ button-based QuizCard/AnsweredCard (ask answers never graded)
- pi fully removed: TUI, extensions, Fastify+WS server, bridge, custom
protocol all deleted (recoverable from git history)
- tests: question-core units carry over; chat-flow integration drives
handleChatRequest with MockLanguageModelV4 (48 tests, zero tokens);
render smoke tests guard the cards (renderToStaticMarkup)
Carried over unchanged: teacher system prompt, question-core, schema/
ledger/derive/extract pipeline, data model.
Amos