Root cause (postmortem, verified live): Chromium caps 6 concurrent
HTTP/1.1 connections per origin. Every running turn pinned slots for
its whole life — the POST /api/chat response stream plus a reattach
GET stream per visit that never closed on navigate-away — so two
concurrent thinking sessions starved navigation RSC fetches in the
browser queue (147s measured) until the turns settled. Server was
exonerated (3ms curls during the freeze); main thread idle throughout.
- COMPACTION LAW + WIRE DIET (ui-stream): store the states, not the
chunks — replace-in-place snapshot retention keyed by updateSlots,
~100ms coalesced latest-wins fan-out, slim wire drops pi's duplicate
assistantMessageEvent payload.
- DIET B: POST /api/chat acks and closes ({ok:true}) — the turn wire
is GET /stream for everyone, submitter included; send() reattaches
via refetch-first resumeStream(true).
- DIET A: unmount cleanup calls model.stop() — navigating away aborts
the view connection (turns are server-side background objects).
- Answer-flicker fix: resumeStream's eager tail clear moved off the
refetch path (the refetch swaps base+tail atomically; clean-slate
guard restored on refetch failure) — the optimistic answer card
survives refetch latency (1.7s stalls measured on dev).
- Tests converted to the ack contract (drainTurn/drainRunning helpers,
dietFetch mock) + a pin that the POST body reads while the turn runs.
Gates: 1489/1489, typecheck, lint. Live: dual streaming sessions,
navigations 335-648ms, in-page settings 19ms (was 147s).
Owner ruling (2026-10-06): every concluded problem opens a pause. The
agent may speak its closing words about the learner's last thinking
after the conclude result, then ENDS ITS TURN — a system-prompt law
deliberately, per owner correction, NOT tool-level terminate. The next
problem is never posed until the learner explicitly moves on; the pause
is the session's teaching space (repairs, clarifications, follow-ups —
still surgical, never re-teaching).
The move-on signal is a first-class input: { type: "next" } appends a
practice-next marker (content = single-sourced NEXT_PROBLEM_TEXT — the
model's unambiguous go-ahead: pose per the selection rules or wrap if
the arc is complete). Honest 400s: practice sessions only, nothing
active (mid-problem input rides the dock), riding after any pending
dismissal synthesis exactly like text.
The fast path (owner approved: composer-band chip + Enter-on-empty):
- Composer.enterAction gains "next" — Enter on an EMPTY composer in
the pause fires the signal; typing anything makes Enter a send again;
busy (steer/stop) outranks the pause.
- The Next chip hovers at the composer band's top-right (pick-pill
chrome register) whenever the pause is live and a problem has ever
been posed; the placeholder becomes the hint ("Ask about this
problem — or press Enter for the next one…", exact);
- the transcript renders the signal as a compact centered NEXT PROBLEM
line (mono-caps chrome); session-core appends it optimistically.
CONCLUDE_ACK_TEXT rewritten to carry the law; doctrine §VIII gains the
pause law (owner-sanctioned edit #3); 00-base's conclude/dismissal
bullets rewritten + the between-problems section added.
Owner round 2 (2026-10-05), Slice H: the Nudge/Commit two-lane buttons
are gone. One Send; Enter sends, Shift+Enter is a newline. Whether a
submission claims an answer is apparent from the thinking itself — the
agent reads it (hint ladder for traces, moves+verdict for claims).
- The thinking input loses the commit field end-to-end: ChatInput,
parseChatInput, newThinkingMessage (details and the model-facing label
both collapse to the single 'Your thinking'), the optimistic marker.
- Legacy records' commit flags are deliberately unread.
- Doctrine: the two labeled channels become one read instruction; 'answer
commits' section retitled 'Claimed answers' — a claim is not a
progress signal.
- ThinkingCard: one label, collapsed arrival (the unified row).
- The dock placeholder no longer explains lanes that no longer exist.
The thinking-submission incident (owner report, 2026-10-05): two spinners
sandwiching the submitted thinking card, and the card doubling once tokens
flowed. Records on disk were clean — both bugs were live-view-only.
- view.ts LIVE IS POSITIVE EVIDENCE (owner ruling): a tool call renders
live (input-streaming) ONLY when its own message is streaming THIS turn
(streamingIds) — session busyness can never resurrect a settled call.
The pose turn's problem call kept flipping to a mid-transcript spinner
because the fallback keyed on live.inFlight. applyResultTo's placeholder
fork now also MARKS the settled ack (input-available) instead of leaving
the guessed state standing. Live cards now sit at the bottom by
construction, never mid-transcript.
- session-core.ts absorbed(): the custom role gets its identity key
(customType + details deep-equal) — the optimistic thinking marker is
dropped when the write-ahead's server copy lands, so the +400ms
adoption window can no longer double the card. Total over roles; types
that never appear optimistically never reach the branch.
Pinned: settled problem never live mid-turn; this turn's streaming call
stays shimmer; dangling-settled is input-available; absorbed by
customType+details (different details = different submission); model-level
adoption keeps exactly one marker.
- PracticeDock (components/practice-dock.tsx): the active problem
replaces the composer — statement (markdown+LaTeX) above, the 'Your
thinking' composer-twin below with the two submit lanes (Nudge =
thinking without a commit; Commit = answer commit; ⌘/Ctrl+Enter
commits). Dictation claims the thinking field.
- Transcript cards (practice-cards.tsx + the artifact registry): the
problem card (compact-expandable statement — the commitment NEVER
renders), the conclude card (outcome + verdict + reveal; the
dismissal synthesis is one muted line), and the user-side thinking
register cards (Your thinking / Your solution).
- view.ts: the problem pose joins the placeholder fork (the ack never
flips the part); practice-thinking markers project as data parts;
problem-dismissed markers project nothing.
- chat.tsx: activeProblemOf drives the dock branch (question > problem
> composer), the esc layering gains the problem rung (below question,
above turn) with its discard confirm + the silent marker route; the
thinking submissions POST through the session's optimistic appends.
STEERING, NOT FOLLOW-UPS — pi-agent-core's two rails, used deliberately:
agent.steer() injects at the next response boundary INSIDE the live run
(one logical turn, the model changes course); followUp() would only extend
an ended run — not built. The same rail job markers already ride
(steeringMode 'all', the 2026-09-26 doctrine).
- POST /api/chats/[id]/steer: 404/400 honest guards; no live turn → 409
and the client silently falls back to a plain text send (the settle
race); live → steerLiveChat hands the message to the live agent's
steering queue AND parks it in the userSteers registry — the stranding
safety net. A steer stranded behind a question termination or abort
stays parked and rides the chat's NEXT run (handOffEligible), the same
deliver-or-requeue lifecycle as job markers. Reconciliation at settle:
delivered ids drop (reconcileUserSteers).
- Client: steer(text) queues + POSTs without flipping any turn state;
the drain's verbatim message events upsert the real user card by the
client-minted id (steer_<localid>) and the indicator fold drops the
line. canSend no longer gates on turnInFlight — Enter mid-turn steers;
Enter with an empty composer still stops; the square button stays Stop.
- The queued-steer indicator (owner spec): quiet one-liners above the
composer shell — right-aligned to where its corner rounding starts,
truncated with an ellipsis, fixed max width, ~half opacity, no
background, no container. Tunable later.
- Verified from pi-agent-core source: steering drains per completed turn
inside the loop; injected messages emit message_start/end verbatim;
finishTurn {action:'end'} (our question stopper) exits BEFORE the
steering poll — hence the registry.
- {type:"dismiss"} input event: parse + pure appends with the answer-event
orphan discipline (dangling-call 400, kind match, answer must be dismissed)
- POST /api/chats/[id]/dismiss: the no-turn composition — write-ahead append,
409 while a turn runs, emits record-changed (new bus word; idle views sync)
- needsContinuation: an all-dismissed trailing batch demands nothing;
endsInDismissal = the derived pause predicate (tail-based, no latch)
- wake pipeline: while the record ends in a dismissal the pump holds every
delivery in the steer queue — the user's next send is the wake (until the
text-turn steer claim lands, settlement re-pump delivers right after it)
- session-core.dismissQuestion: optimistic skipped card + silent POST;
chat.tsx confirmAbort question-mode swaps submitAnswer for it; ESC-abort
popup everywhere (AbortTurnDialog) with popup-Esc claimed via state gate
- parallel question calls dismiss call-by-call (results bind by id)
The Accept/Decline verdict gate is gone (owner ruling 2026-09-26):
presenting the plan ends the teacher's turn; the learner's next message
is a natural reply. Teaching begins at the first quiz call tagged with a
nodeId (probe quizzes carry none) — both folds (view phaseAt3, native
phaseAt3Lh) advance on the call itself, and the teach divider renders
before that whole assistant block. No backwards compat: verdict markers,
the verdict input event, optimistic appends, composer buttons, and
projection all deleted; prompts and docs rewritten to the natural flow.
Delivery now rides pi's OWN follow-up queue when a run is live, and a
carry-everything idle wake otherwise. One registry, two vehicles;
claimSteers and continuation coalescing are deleted (owner rulings,
2026-09-26: follow-ups only; one queue; the wake is the only appender).
THE LIVE RUN (vehicle 1): the chat-handler registers the streaming
turn's agent (registerLiveAgent, next to registerTurn); the pump hands
every eligible queued marker to agent.followUp() - pi polls that queue
when the run would otherwise stop, injects the markers
(message_start/message_end on the live wire), and CONTINUES the same
run. followUpMode "all" joins every handed marker in one continuation
turn. The question stopper runs before the follow-up poll, so an open
quiz is never overridden - a handed marker strands at settlement and
waits (today's pacing). probe-handoffs never take this path (the
handoff must START the teacher's run - a record-level branch).
SETTLEMENT RECONCILIATION: settleSteers(chatId, persisted) at onFinish
(after unregisterLiveAgent) resolves+flips entries the run delivered
and returns stranded ones to pending - the registry stays the truth;
the dead agent's queued copy is abandoned. This is what makes the
handoff safe: pi owns no retry for a stranded follow-up.
THE IDLE WAKE (vehicle 2): waitForIdle (unchanged gates) then ONE turn
carrying EVERY pending marker as its input appends - dequeue-at-fire
(the Wave B regression lesson: the wake run's own follow-up poll must
never see its own cargo; a 409 pushes the cargo back and retries).
CLIENT: applyWireEvent now upserts non-assistant messages by id, so
in-run injected markers render live instead of dropping until settle.
Tests: jobs 44/44 (live handoff, settlement stranding, handoff-waits,
one-wake-carries-all); chat-flow 23/23 (the double-append pin drives
the real pump through the new input); session-core 28/28 (custom-role
wire appends). Full suite 997/997, tsc/lint/build green.
Live smoke (PORT=3004): research job delivered mid-probe - parked
behind the dangling questions exactly per semantics, landed once on
the open gates, teacher folded the brief in and re-dispatched; the
second (good) result rendered the full 10-source brief card and the
lesson continued from it. No duplicate ids anywhere in the record.
Known gap flagged to owner (NOT from this change): the server accepts
malformed answer events via raw API (answers without the answers[]
shape) and AnsweredCard then crashes the page render - surfaced by the
smoke's scripted answers, repaired by hand in the scratch record.
pi streams AssistantMessages with NO id (verified against a captured
live stream and pi-ai's AssistantMessage type): the id exists only once
the server's persistTurn stamps the record. applyWireEvent minted a
FRESH c_ id per event, so message_start appended, every message_update
found no match and APPENDED another full copy, and message_end appended
again - the tail grew one message per chunk. projectView's step
separators + thinking blocks then filled the transcript with dividers
and thinking indicators mid-stream (with fresh React keys remounting
the whole subtree per chunk), cleaned up only by the settle sync's
setMessages(record).
The fix: the in-flight assistant message is tracked by SLOT -
message_start mints and remembers one client id; message_update and
message_end REPLACE that same tail entry (pi guarantees exactly one
streaming message at a time via its strict start-updates-end ordering;
the reattach replay replays the same sequence). An explicit
message.id on the wire still wins; the slot clears at message_end,
stop(), and setMessages().
Tests: all streaming fixtures rewritten to pi's real shape (no
message.id) - the old ones encoded the wrong assumption - plus a
regression pin asserting N id-less updates leave exactly ONE assistant
message in the tail with a stable slot id.
Verified live mid-stream (DOM sampled every 500ms during a teaching
turn): 0 separators throughout, thinking blocks 1-2 (one per step, not
per chunk), text growing smoothly.
Live-driven via the owner's dev server (browser tools), reproduced on
/chat/new: send fires, optimistic appends, POST never happens, and the
page shows the frozen empty state. Three compounding defects:
1. session-core: default fetch stored UNBOUND — the browser's native
fetch requires this === Window, so every call threw 'Illegal
invocation' and the POST /api/chat never fired. Node's undici has no
receiver discipline, which is why 994/994 tests passed while the app
was dead. Now defaulted through a receiver-preserving wrapper; pinned
by a strict-this regression test (the browser's semantics simulated.
2. session.ts: state memo keyed on [model, forceRender] — the reducer
dispatch is STABLE by contract, so the memo computed once per mount:
no optimistic bubble, no stream events, no error banner. The view was
frozen at first render. Rekeyed on a version counter bumped by the
model's onChange.
3. view.ts: turn_end carries the clean 'Question posed' placeholder as
a toolResult message (details: null) — applyResult flipped the quiz
part to output-available with a null output and AnsweredCard crashed
on answer.dismissed (killed the whole page render). Fork 2 now holds
on the message-attachment path too: clean question results with null
details are ignored; the AnsweredCard renders only the learner's real
answer. Regression pin extended in session-core.test.ts.
Verified live end to end: new session → text send → probe questions in
the dock → ask answer → graded ✓ quiz card with explanation → reload
renders the full transcript from the native record with the pending
question intact.
EOF
)
Server: ui-stream.ts is verbatim pi AgentEvent passthrough (SSE data
lines + [DONE]); only app-level events are the loop-level error and
turn-settled terminal; onError carries raw provider text (owner ruling).
Client: useChat + the AI-SDK transport replaced by components/session-core.ts
(SessionModel: 409 identity-retry, optimistic c_ appends, absorbed()
adoption, needsContinuation, shared consume for POST + reattach) and the
session.ts hook; the golden-master grouping canon moved client-side into
core/view.ts (projectView); scanners read the native record (phaseAt3Lh,
danglingQuestionOf, graph toolParts, plan-blocks, runner, extraction).
Coverage: the native message is the unit (fork 3) with the call+result
inseparability bond rule; view-line-less messages (markers, error
results) are invisible to coverage and never checkpointed.
Deletes: chat-transport, projection, ui-message, their tests (ported to
tests/session-core.test.ts), and the ai + @ai-sdk/react dependencies —
the Vercel SDK is fully out of the tree. Wire pins in chat-flow rewritten
onto the AgentEvent dialect (eventsOf parser).
Gates: tsc clean, 994/994 tests, eslint clean, build green; live smoke
on PORT=3004 (verbatim wire → native record).
amosblomqvist