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.

app/api/activity/abort/route.ts

@@ -17,7 +17,7 @@
  * Extraction abort is idempotent by design (aborting with nothing in
  * flight is success — the blob is gone either way) -> 200.
  */
-import { abortExtraction, abortJob, abortTurn } from "@/src/server";
+import { abortExtraction, abortJob, abortTurn, practice } from "@/src/server";
 
 export async function POST(req: Request) {
 	let body: unknown;
@@ -27,8 +27,8 @@ export async function POST(req: Request) {
 		return Response.json({ error: "Invalid JSON body" }, { status: 400 });
 	}
 	const { kind, id } = (body ?? {}) as { kind?: string; id?: string };
-	if ((kind !== "job" && kind !== "extraction" && kind !== "turn") || typeof id !== "string" || id === "") {
-		return Response.json({ error: 'Body must be {kind: "job"|"extraction"|"turn", id: string}' }, { status: 400 });
+	if ((kind !== "job" && kind !== "extraction" && kind !== "turn" && kind !== "practice") || typeof id !== "string" || id === "") {
+		return Response.json({ error: 'Body must be {kind: "job"|"extraction"|"turn"|"practice", id: string}' }, { status: 400 });
 	}
 	if (!/^[A-Za-z0-9_-]+$/.test(id)) {
 		return Response.json({ error: "Invalid id" }, { status: 400 });
@@ -49,6 +49,13 @@ export async function POST(req: Request) {
 	}
 	// kind === "extraction": true cancellation; idempotent (nothing in
 	// flight is success — same dock outcome)
+	if (kind === "practice") {
+		// practice slice 4 (2026-09-29): abort BOTH of a set's live runs
+		// (generation + grading) and mark the persisted "Aborted" state —
+		// idempotent like extraction (nothing in flight is success).
+		practice.abortPractice(id);
+		return Response.json({ ok: true });
+	}
 	abortExtraction(id);
 	return Response.json({ ok: true });
 }

app/api/practice/sets/[id]/answers/route.ts

@@ -0,0 +1,19 @@
+/**
+ * POST /api/practice/sets/[id]/answers — submit answers for grading
+ * (202; one grading job per answered problem runs in the background).
+ * Body: {answers: [{problemId, text}]}. Set must be ready; answers must
+ * be non-empty text on known, not-yet-graded problems (400/409 via the
+ * service's typed-error mapping).
+ */
+import { submitPracticeAnswersResponse } from "@/src/server";
+
+export async function POST(req: Request, { params }: { params: Promise<{ id: string }> }) {
+	const { id } = await params;
+	let body: unknown;
+	try {
+		body = await req.json();
+	} catch {
+		return Response.json({ error: "Invalid JSON body" }, { status: 400 });
+	}
+	return submitPracticeAnswersResponse(id, body);
+}

app/api/practice/sets/[id]/route.ts

@@ -0,0 +1,29 @@
+/**
+ * GET /api/practice/sets/[id] — one problem set (the exam page polls
+ * this while status ≠ ready; graph-view's reveal-poll idiom).
+ * DELETE — abort the set's live jobs, then drop the record (the unified
+ * delete doctrine: no orphans, no zombies). 404 when never existed.
+ */
+import { getPracticeSet, practice, practiceErrorResponse } from "@/src/server";
+
+export async function GET(_req: Request, { params }: { params: Promise<{ id: string }> }) {
+	const { id } = await params;
+	try {
+		const set = getPracticeSet(id);
+		if (!set) return Response.json({ error: "no practice set", code: "not_found" }, { status: 404 });
+		return Response.json({ set });
+	} catch (err) {
+		return practiceErrorResponse(err);
+	}
+}
+
+export async function DELETE(_req: Request, { params }: { params: Promise<{ id: string }> }) {
+	const { id } = await params;
+	try {
+		const existed = await practice.deleteProblemSet(id);
+		if (!existed) return Response.json({ error: "no practice set", code: "not_found" }, { status: 404 });
+		return Response.json({ ok: true });
+	} catch (err) {
+		return practiceErrorResponse(err);
+	}
+}

app/api/practice/sets/route.ts

@@ -0,0 +1,27 @@
+/**
+ * POST /api/practice/sets — create a problem set (202 {id}; generation
+ * runs in the background — the fire-and-forget pipeline). Body:
+ *   {chatId, params}          — everything this session touched
+ *   {nodeIds, params}         — a manual node selection
+ * Validation + typed-error mapping live in the service (server/practice).
+ * GET — the set list (createdAt desc, the store's order).
+ */
+import { createPracticeSetResponse, listPracticeSets, practiceErrorResponse } from "@/src/server";
+
+export async function POST(req: Request) {
+	let body: unknown;
+	try {
+		body = await req.json();
+	} catch {
+		return Response.json({ error: "Invalid JSON body" }, { status: 400 });
+	}
+	return createPracticeSetResponse(body);
+}
+
+export async function GET() {
+	try {
+		return Response.json({ sets: listPracticeSets() });
+	} catch (err) {
+		return practiceErrorResponse(err);
+	}
+}