practice slice 4 — pipeline, registry, API, feed

src/agent/subagents/practice-pipeline.ts (sibling of practice.ts —
orchestration vs calls): createPracticePipeline(graphStore+practiceStore
+chatStore+PracticeModels). Fire-and-forget front doors returning
{set, done}: createProblemSet (refuse → resolve selection (chatId =
ANY-provenance membership per brief; nodeIds raw) → chains → snapshot →
createSet partitioning → registry row → runPartitioner → stubs land
(generating) → ONE generator per problem behind the process-wide
3-permit abort-aware semaphore (__lhPracticeSlots, extraction idiom) →
per-problem failure isolation → ready (errored problems included);
abortPractice (idempotent: controllers + 'Aborted' marks; dropped
grades keep answers, re-submittable); submitAnswers (ready-only,
already-graded rejects, one grading job per answer under the same
semaphore); deleteProblemSet (abort-first). Per-set write mutex on
globalThis (__lhPracticeLocks, audit-lock idiom); registry
__lhPracticeRuns one row per set per kind; boot sweep marks orphaned
partitioning/generating sets 'Interrupted (server restarted)'. Typed
errors: EmptySelection/UnknownChat/SetNotFound/SetNotReady/BadAnswers.
Usage folds stage logs into the registry row (v1: completion-folded).

src/server/practice.ts: thin service — strict params parsing, typed
error → response mapping (503 envelope family, 400/404/409), list/get.
Routes: POST+GET /api/practice/sets (202 {id}), GET+DELETE
/api/practice/sets/[id], POST /api/practice/sets/[id]/answers (202).
Composition root: chat-handler wires createPracticePipeline (engineFor
fresh + providerKeyMissing gate) exported as ; barrel re-
exports. Feed: observability activityFeed() += practice rows
(ActivityPractice); dock blobs (process 'practice', GraduationCap
icon, set-keyed abort); /api/activity/abort kind 'practice'.

tests/practice-pipeline.test.ts — 13 tests: end-to-end (stubs mid-
flight via gated generators, coverage complete), failure isolation,
3-permit semaphore pin, abort mid-generation, registry shape pins,
refusal-before-create, chatId any-provenance selection, typed errors,
answers→grades land + graded rejects, boot sweep (orphan + live-row),
delete. 1114/1114, tsc 0, lint 0, build 0.
This commit is contained in:
amosblomqvist
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/**
* THE PRACTICE PIPELINE (practice arc, slice 4 — 2026-09-29): the
* orchestration around the practice agents (slice 3) — set creation,
* two-stage generation (partitioner → one generator per problem), answer
* submission, grading, abort, and the live-run registry the activity
* feed reads. Sibling of practice.ts (the agents + their doctrines);
* this module owns STATE, the agents module owns CALLS.
*
* ARCHITECTURE (extraction's idioms, deliberately):
* - Live runs live on globalThis.__lhPracticeRuns — one row per set per
* kind ("${setId}:generation" | "${setId}:grading") — because Next dev
* compiles each route entry as its own module instance; a module-level
* Map would read empty from /api/activity. One process, one truth
* (the turn/wake/abort/extraction registries' lesson).
* - Every set-file mutation funnels through the per-set write mutex
* (the audit-lock idiom, per-set): the STORE adapter stays dumb —
* serialization is THIS layer's job (store module's contract).
* - Model calls (generators, graders) gate behind a process-wide
* 3-permit semaphore (__lhPracticeSlots) — the same provider-facing
* rate stance as extraction's slots; abort-aware while queued.
* - The store adapter isSYNC (fs); reads may run unlocked, only
* read-modify-write cycles take the lock.
*
* FIRE-AND-FORGET front doors: createProblemSet persists the set at
* "partitioning" and returns immediately — the pipeline runs in the
* background; the returned `done` promise is the test/diagnostic seam
* (routes ignore it). submitAnswers mirrors it for grading. All
* background failure paths settle the persisted record (never an
* unhandled rejection); aborts mark "Aborted".
*
* GRADING FAILURE DISCIPLINE: an aborted or failed grade leaves the
* answer in place, the grade absent — the problem is re-submittable
* later (a new grading job). A second submitAnswers while grading is in
* flight is rejected (single live grading run per set).
*/
import type { ChatStore, GraphStore, PracticeStore } from "../../core/ports.ts";
import type { Problem, ProblemSet, ReasoningChain } from "../../core/contracts.ts";
import { chainsForSelection } from "../../core/practice.ts";
import {
createPracticeAgents,
type PracticeModels,
type PracticeStepLog,
type PreviousProblemRef,
type PropositionSnapshot,
} from "./practice.ts";
// ─── typed errors (the service maps these to responses) ──────────────────────
/** The selector resolved to nothing practicable (400 at the route). */
export class EmptySelectionError extends Error {
constructor(message = "selection has no propositions to practice") {
super(message);
this.name = "EmptySelectionError";
}
}
/** chatId path: the chat record is gone (404). */
export class UnknownChatError extends Error {
constructor(chatId: string) {
super(`no chat ${chatId}`);
this.name = "UnknownChatError";
}
}
/** Set id unknown (404). */
export class PracticeSetNotFound extends Error {
constructor(setId: string) {
super(`no practice set ${setId}`);
this.name = "PracticeSetNotFound";
}
}
/** The set exists but is not in the state the caller needs (409). */
export class PracticeSetNotReady extends Error {
constructor(status: ProblemSet["status"]) {
super(`practice set is ${status}, not ready`);
this.name = "PracticeSetNotReady";
}
}
/** Malformed answers: unknown problem, empty text, already graded, or a
* grading run already in flight (400). */
export class BadAnswersError extends Error {
constructor(message: string) {
super(message);
this.name = "BadAnswersError";
}
}
// ─── the live-run registry (globalThis — see module doc) ─────────────────────
export type PracticeRunKind = "generation" | "grading";
export type PracticePhase = "partitioning" | "generating" | "grading";
/** One live run row — generation or grading, per set. Mirrors
* RunningExtraction's shape discipline (label carries the progress the
* dock renders; usage folds stage logs as they land). */
export interface RunningPractice {
/** `${setId}:generation` | `${setId}:grading` — the registry key. */
key: string;
setId: string;
kind: PracticeRunKind;
phase: PracticePhase;
/** Set title + progress ("T — problem 2/5") — the dock's line. */
label: string;
startedAt: number;
/** Stage usage, folded from each runner's returned PracticeStepLog
* as its call settles (v1: completion-folded, not per-step — the
* practice blobs ride no live cost channel). */
usage: {
partitioner?: PracticeStepLog;
generator?: PracticeStepLog;
grader?: PracticeStepLog;
};
/** True-cancellation (the dock's abort): shared across the run's
* model calls; abort() also kills queued semaphore tickets. */
controller: AbortController;
}
interface LhPracticeGlobal {
__lhPracticeRuns?: Map<string, RunningPractice>;
/** Per-set write mutexes (audit-lock idiom, per-set). */
__lhPracticeLocks?: Map<string, { tail: Promise<void> }>;
/** The PRACTICE SEMAPHORE: 3 concurrent practice model calls,
* process-wide — shared by generators and graders (the same
* provider-facing stance as extraction's extract slots). */
__lhPracticeSlots?: { active: number; queue: { resolve: () => void; dead: boolean }[] };
}
function practiceRuns(): Map<string, RunningPractice> {
const g = globalThis as typeof globalThis & LhPracticeGlobal;
return (g.__lhPracticeRuns ??= new Map());
}
function practiceLocks(): Map<string, { tail: Promise<void> }> {
const g = globalThis as typeof globalThis & LhPracticeGlobal;
return (g.__lhPracticeLocks ??= new Map());
}
/** In-flight practice runs, oldest first (the feed sorts again; this is
* the stable, deterministic order tests pin). */
export function practiceStatuses(): RunningPractice[] {
return [...practiceRuns().values()].sort((a, b) => a.startedAt - b.startedAt);
}
/** The per-set serialized write section: read-modify-write cycles around
* one set's file queue here, process-wide. */
async function withSetLock<T>(setId: string, critical: () => Promise<T> | T): Promise<T> {
const locks = practiceLocks();
const prev = locks.get(setId)?.tail ?? Promise.resolve();
let release!: () => void;
const mine = new Promise<void>((resolve) => (release = resolve));
locks.set(setId, { tail: prev.then(() => mine) });
await prev;
try {
return await critical();
} finally {
release();
}
}
/** The 3-permit practice semaphore — extraction's withExtractSlot idiom,
* signal taken directly (the caller's row controller). A queued ticket
* that aborts marks itself dead: the permit handoff skips it (fresh
* takers count themselves; handed-off permits don't — the double-count
* deadlock lesson, extraction 2026-09-28). */
async function withPracticeSlot<T>(signal: AbortSignal | undefined, critical: () => Promise<T>): Promise<T> {
const g = globalThis as typeof globalThis & LhPracticeGlobal;
const slots = (g.__lhPracticeSlots ??= { active: 0, queue: [] });
let freshTake = true;
if (slots.active >= 3) {
freshTake = false;
await new Promise<void>((resolve, reject) => {
const ticket: { resolve: () => void; dead: boolean } = { resolve, dead: false };
slots.queue.push(ticket);
if (!signal) return;
const die = () => {
ticket.dead = true;
const err = new Error("practice run aborted while queued for a slot");
err.name = "AbortError";
reject(err);
};
if (signal.aborted) die();
else signal.addEventListener("abort", die, { once: true });
});
}
if (freshTake) slots.active++;
try {
return await critical();
} finally {
for (;;) {
const next = slots.queue.shift();
if (!next) {
slots.active--;
break;
}
if (next.dead) continue;
next.resolve();
break;
}
}
}
// ─── small helpers ───────────────────────────────────────────────────────────
/** "pp_" + ts36 + rand — mirrors the store's ps_ minting. */
function newProblemId(): string {
return `pp_${Date.now().toString(36)}_${crypto.randomUUID().slice(0, 8)}`;
}
function isAbortLike(err: unknown): boolean {
return err instanceof Error && err.name === "AbortError";
}
function messageOf(err: unknown): string {
return err instanceof Error ? err.message : String(err);
}
function foldUsage(
target: RunningPractice["usage"],
stage: "partitioner" | "generator" | "grader",
log: PracticeStepLog,
): void {
const cur = target[stage];
if (!cur) target[stage] = { model: log.model, steps: [...log.steps] };
else {
if (!cur.model) cur.model = log.model;
cur.steps.push(...log.steps);
}
}
function registerRow(key: string, setId: string, kind: PracticeRunKind, phase: PracticePhase, label: string): RunningPractice {
const row: RunningPractice = {
key,
setId,
kind,
phase,
label,
startedAt: Date.now(),
usage: {},
controller: new AbortController(),
};
practiceRuns().set(key, row);
return row;
}
/** DEDUP INPUT (computed ONCE at creation, passed to partitioner and
* every generator): ready problems from the most recent ≤5 sets sharing
* at least one selected node. */
function dedupInput(practiceStore: PracticeStore, selected: ReadonlySet<string>): PreviousProblemRef[] {
const refs: PreviousProblemRef[] = [];
let setsSeen = 0;
for (const set of practiceStore.listSets()) {
if (setsSeen >= 5) break;
if (!set.nodeIds.some((id) => selected.has(id))) continue;
setsSeen++;
for (const p of set.problems) {
if (p.status === "ready" && p.statement !== "") refs.push({ statement: p.statement, chains: p.chains });
}
}
return refs;
}
// ─── the pipeline ────────────────────────────────────────────────────────────
export interface PracticePipelineDeps extends PracticeModels {
graphStore: GraphStore;
practiceStore: PracticeStore;
/** Titles for the chat-born path (and existence: unknown chat → 404). */
chatStore: Pick<ChatStore, "getChat" | "listChats">;
}
export function createPracticePipeline(deps: PracticePipelineDeps) {
const agents = createPracticeAgents(deps);
// BOOT SWEEP: a persisted partitioning/generating set with no live row
// is a crash/restart orphan (the registry is memory-only) — mark it,
// idempotently. Runs at every pipeline instantiation (dev route
// entries re-run it; live rows are globalThis-shared and skipped).
for (const set of deps.practiceStore.listSets()) {
if (
(set.status === "partitioning" || set.status === "generating") &&
!practiceRuns().has(`${set.id}:generation`)
) {
set.status = "error";
set.error = "Interrupted (server restarted)";
deps.practiceStore.saveSet(set);
}
}
/** Persist the error state on a set (partitioner failure / abort). */
async function markSetError(setId: string, message: string): Promise<void> {
await withSetLock(setId, () => {
const cur = deps.practiceStore.getSet(setId);
if (!cur) return;
cur.status = "error";
cur.error = message;
deps.practiceStore.saveSet(cur);
});
}
// ── generation ───────────────────────────────────────────────────────
async function generateSet(
set: ProblemSet,
previousProblems: PreviousProblemRef[],
row: RunningPractice,
): Promise<void> {
const controller = row.controller;
// Stage 1 — the partitioner.
let partitions: Array<{ chains: string[] }>;
try {
const submitted = await agents.runPartitioner({
chains: set.chains,
propositions: set.propositions,
params: set.params,
previousProblems,
signal: controller.signal,
});
foldUsage(row.usage, "partitioner", submitted.log);
partitions = submitted.partitions;
} catch (err) {
await markSetError(set.id, isAbortLike(err) || controller.signal.aborted ? "Aborted" : messageOf(err));
practiceRuns().delete(row.key);
return;
}
// Stubs appear the moment the partition lands (numbered, generating).
const stubs: Problem[] = partitions.map((part) => ({
id: newProblemId(),
chains: part.chains,
statement: "",
solution: "",
rubric: "",
status: "generating",
}));
const saved = await withSetLock(set.id, () => {
const cur = deps.practiceStore.getSet(set.id);
if (!cur) return null;
cur.problems = stubs;
cur.status = "generating";
deps.practiceStore.saveSet(cur);
return cur;
});
if (!saved) {
practiceRuns().delete(row.key); // deleted mid-run — stop quietly
return;
}
row.phase = "generating";
let settled = 0;
row.label = `${set.title} — problem 0/${stubs.length}`;
// Stage 2 — one generator per problem, failure-isolated, 3-wide.
await Promise.all(
stubs.map(async (stub) => {
try {
await withPracticeSlot(controller.signal, async () => {
if (controller.signal.aborted) {
const err = new Error("aborted while queued");
err.name = "AbortError";
throw err;
}
const generated = await agents.runProblemGenerator({
target: stub.chains,
fullChains: set.chains,
propositions: set.propositions,
params: set.params,
previousProblems,
signal: controller.signal,
});
foldUsage(row.usage, "generator", generated.log);
await withSetLock(set.id, () => {
const cur = deps.practiceStore.getSet(set.id);
if (!cur) return;
const p = cur.problems.find((q) => q.id === stub.id);
if (!p) return;
p.chains = generated.problem.chains;
p.statement = generated.problem.statement;
p.solution = generated.problem.solution;
p.rubric = generated.problem.rubric;
p.status = "ready";
p.error = undefined;
deps.practiceStore.saveSet(cur);
});
});
} catch (err) {
// Failure isolation: this problem errors, the set runs on.
const aborted = isAbortLike(err) || controller.signal.aborted;
await withSetLock(set.id, () => {
const cur = deps.practiceStore.getSet(set.id);
if (!cur) return;
const p = cur.problems.find((q) => q.id === stub.id);
if (!p) return;
p.status = "error";
p.error = aborted ? "Aborted" : messageOf(err);
deps.practiceStore.saveSet(cur);
});
} finally {
settled++;
row.label = `${set.title} — problem ${settled}/${stubs.length}`;
}
}),
);
// Settle: ready even with errored problems (per-problem isolation);
// aborted runs keep the error abortPractice already wrote.
await withSetLock(set.id, () => {
const cur = deps.practiceStore.getSet(set.id);
if (!cur) return;
if (controller.signal.aborted) {
cur.status = "error";
cur.error = "Aborted";
} else {
cur.status = "ready";
cur.error = undefined;
}
deps.practiceStore.saveSet(cur);
});
practiceRuns().delete(row.key);
}
/**
* Create a problem set — fire-and-forget: persists the set at
* "partitioning" and returns it immediately; `done` resolves when
* generation has fully settled (any end state). Refusal gates
* (models/key) fire BEFORE anything is created.
*/
async function createProblemSet(
selector: { chatId: string } | { nodeIds: string[] },
params: ProblemSet["params"],
titleHint?: string,
): Promise<{ set: ProblemSet; done: Promise<void> }> {
agents.refuseIfStagesUnready();
// Resolve the selection: chatId = any-provenance membership (owner:
// a node belongs to a session when ANY provenance point names it —
// birth-session clustering deliberately NOT used here); nodeIds =
// the raw list, unknown ids simply drop.
let sourceTitle: string | undefined;
let selected;
if ("chatId" in selector) {
const chat = deps.chatStore.getChat(selector.chatId);
if (!chat) throw new UnknownChatError(selector.chatId);
sourceTitle = chat.title;
selected = deps.graphStore.readNodes().filter((n) => n.provenance.some((pt) => pt.chatId === selector.chatId));
} else {
const wanted = new Set(selector.nodeIds);
selected = deps.graphStore.readNodes().filter((n) => wanted.has(n.id));
}
const selectedIds = new Set(selected.map((n) => n.id));
const edges = deps
.graphStore.readEdges()
.filter((e) => e.type === "follows" && selectedIds.has(e.from) && selectedIds.has(e.to));
const chains = chainsForSelection(selected, edges);
if (chains.length === 0) throw new EmptySelectionError();
const propositions: PropositionSnapshot = {};
for (const n of selected) propositions[n.id] = { name: n.name, statement: n.statement };
const title = titleHint ?? sourceTitle ?? `Practice — ${new Date().toISOString().slice(0, 10)}`;
const set = deps.practiceStore.createSet({
title,
createdAt: new Date().toISOString(),
params,
nodeIds: [...selectedIds].sort(),
propositions,
chains,
status: "partitioning",
problems: [],
});
const previousProblems = dedupInput(deps.practiceStore, selectedIds);
const row = registerRow(`${set.id}:generation`, set.id, "generation", "partitioning", title);
const done = generateSet(set, previousProblems, row);
return { set, done };
}
// ── grading ──────────────────────────────────────────────────────────
/**
* Save answers and spawn one grading job per answered problem —
* fire-and-forget like creation: the persisted set carries the
* answers immediately; grades land as their jobs settle.
*/
async function submitAnswers(
setId: string,
answers: Array<{ problemId: string; text: string }>,
): Promise<{ set: ProblemSet; done: Promise<void> }> {
agents.refuseIfStagesUnready(); // grading needs its engine — refuse BEFORE saving answers
if (practiceRuns().has(`${setId}:grading`)) {
throw new BadAnswersError("a grading run is already in flight for this set");
}
const set = await withSetLock(setId, () => {
const cur = deps.practiceStore.getSet(setId);
if (!cur) throw new PracticeSetNotFound(setId);
if (cur.status !== "ready") throw new PracticeSetNotReady(cur.status);
const ids = new Set(cur.problems.map((p) => p.id));
for (const a of answers) {
if (typeof a.problemId !== "string" || !ids.has(a.problemId)) throw new BadAnswersError(`unknown problem id`);
if (typeof a.text !== "string" || a.text.trim() === "") throw new BadAnswersError("answers must be non-empty text");
const p = cur.problems.find((q) => q.id === a.problemId)!;
if (p.grade) throw new BadAnswersError(`problem ${a.problemId} is already graded`);
}
for (const a of answers) {
const p = cur.problems.find((q) => q.id === a.problemId)!;
p.answer = a.text;
}
deps.practiceStore.saveSet(cur);
return cur;
});
const row = registerRow(`${setId}:grading`, setId, "grading", "grading", `${set.title} — grading`);
const done = (async () => {
await Promise.all(answers.map((a) => gradeOne(setId, a.problemId, row)));
practiceRuns().delete(row.key);
})();
return { set, done };
}
/** One grading job — abort/failure drops the grade (answer kept,
* re-submittable later); success writes it under the set lock. */
async function gradeOne(setId: string, problemId: string, row: RunningPractice): Promise<void> {
const controller = row.controller;
try {
await withPracticeSlot(controller.signal, async () => {
if (controller.signal.aborted) return; // dropped — no grade, no error state
const set = deps.practiceStore.getSet(setId);
if (!set) return;
const problem = set.problems.find((p) => p.id === problemId);
if (!problem || problem.grade) return;
// The legend scoped to THIS problem's chains (its premises +
// conclusions) — the grader sees only what it grades.
const legend: PropositionSnapshot = {};
for (const chainId of problem.chains) {
const chain: ReasoningChain | undefined = set.chains.find((c) => c.id === chainId);
if (!chain) continue;
for (const nodeId of [chain.conclusion, ...chain.premises]) {
const p = set.propositions[nodeId];
if (p) legend[nodeId] = p;
}
}
const graded = await agents.runGrader({
problem: { statement: problem.statement, solution: problem.solution, rubric: problem.rubric },
propositions: legend,
answer: problem.answer ?? "",
signal: controller.signal,
});
foldUsage(row.usage, "grader", graded.log);
await withSetLock(setId, () => {
const cur = deps.practiceStore.getSet(setId);
if (!cur) return;
const p = cur.problems.find((q) => q.id === problemId);
if (!p || p.grade) return;
p.grade = { verdict: graded.verdict, feedback: graded.feedback, gradedAt: new Date().toISOString() };
deps.practiceStore.saveSet(cur);
});
});
} catch (err) {
// Grading failure: the grade simply stays absent (re-submittable).
console.error(`[practice] grading failed for ${problemId}:`, isAbortLike(err) ? "aborted" : messageOf(err));
}
}
// ── abort + delete ───────────────────────────────────────────────────
/** True-cancellation for a set's live runs + the persisted "Aborted"
* marks. Idempotent by design (aborting with nothing in flight is
* success — the blob is gone either way), like abortExtraction. */
function abortPractice(setId: string): void {
for (const key of [`${setId}:generation`, `${setId}:grading`]) {
const row = practiceRuns().get(key);
if (row) {
row.controller.abort();
practiceRuns().delete(key);
}
}
const set = deps.practiceStore.getSet(setId);
if (!set) return;
let dirty = false;
for (const p of set.problems) {
if (p.status === "generating") {
p.status = "error";
p.error = "Aborted";
dirty = true;
}
}
if (set.status === "partitioning" || set.status === "generating") {
set.status = "error";
set.error = "Aborted";
dirty = true;
}
if (dirty) deps.practiceStore.saveSet(set);
}
/** Delete a set: live jobs die first, then the record. Boolean like
* the store (false = never existed → the route's 404). */
async function deleteProblemSet(setId: string): Promise<boolean> {
abortPractice(setId);
let existed = false;
await withSetLock(setId, () => {
existed = deps.practiceStore.deleteSet(setId);
});
return existed;
}
return {
createProblemSet,
submitAnswers,
abortPractice,
deleteProblemSet,
};
}