delete the batch practice-problems module (superseded by practice sessions)

Owner ruling 2026-10-04: the module is a sunk cost, retrievable from
history if ever revisited. Removed: core practice contracts + pipeline
helpers, the PracticeStore port + adapter + data dir path, server
service + API routes (sets, clusters picker, practice aborts), the
practice pages + dialog/exam/list UI, chain-table's Generate handoff,
sidebar nav, activity-dock practice rows, and the partitioner/
problemGenerator/grader model roles (BACKGROUND_MODEL_ROLES 8 → 5).

Survivors, moved to core/chains.ts (pure + browser-safe): ReasoningChain,
chainsForSelection, formatChainLine — the chain table and graph
emission still consume them.

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, practice } from "@/src/server";
+import { abortExtraction, abortJob, abortTurn } from "@/src/server";
 
 export async function POST(req: Request) {
 	let body: unknown;
@@ -27,11 +27,9 @@ 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" && kind !== "practice") || typeof id !== "string" || id === "") {
-		return Response.json({ error: 'Body must be {kind: "job"|"extraction"|"turn"|"practice", id: string}' }, { status: 400 });
+	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 });
 	}
-	// Practice row keys carry ":" (setId:gen:problemId) — the charset
-	// admits it for every kind (job/turn/extraction ids never use it).
 	if (!/^[A-Za-z0-9:_-]+$/.test(id)) {
 		return Response.json({ error: "Invalid id" }, { status: 400 });
 	}
@@ -51,14 +49,6 @@ export async function POST(req: Request) {
 	}
 	// kind === "extraction": true cancellation; idempotent (nothing in
 	// flight is success — same dock outcome)
-	if (kind === "practice") {
-		// practice restructure (owner, 2026-09-29): id is the ROW key —
-		// abort routes by shape (a gen row kills THAT problem only; the
-		// partition row ends the run; a grade row drops that grade).
-		// Idempotent like extraction (nothing in flight is success).
-		practice.abortPracticeRow(id);
-		return Response.json({ ok: true });
-	}
 	abortExtraction(id);
 	return Response.json({ ok: true });
 }

app/api/graph/clusters/route.ts

@@ -1,11 +0,0 @@
-/**
- * GET /api/graph/clusters — the birth-session groups for the practice
- * creation picker (owner ruling 2026-09-29: sets are created from graph
- * clusters, node ids only). Thin transport; the grouping is the graph
- * view's own (server/graph.ts → graphSnapshot's clusters).
- */
-import { graphClusters } from "@/src/server";
-
-export async function GET() {
-	return Response.json({ clusters: graphClusters() }, { headers: { "cache-control": "no-store" } });
-}

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

@@ -1,20 +0,0 @@
-/**
- * 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-answered problems (400/409 via the
- * service's typed-error mapping). ONE ATTEMPT (owner 2026-09-29): once a
- * problem carries an answer it is done — re-submission is refused.
- */
-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

@@ -1,29 +0,0 @@
-/**
- * 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

@@ -1,28 +0,0 @@
-/**
- * POST /api/practice/sets — create a problem set (202 {id}; generation
- * runs in the background — the fire-and-forget pipeline). Body:
- *   {nodeIds, params, title?, note?}  — a node selection, the cluster's
- *                                     label, and the learner's optional
- *                                     free-form note
- * 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);
-	}
-}