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.

src/server/observability.ts

@@ -20,6 +20,7 @@
  */
 
 import { extractionStatuses, type ExtractionPhase } from "../agent/subagents/extraction.ts";
+import { practiceStatuses, type PracticePhase } from "../agent/subagents/practice-pipeline.ts";
 import { chatStore } from "../store/chats.ts";
 import { graphRevision } from "./graph.ts";
 import { catalogContextLimits } from "./model-catalog.ts";
@@ -27,6 +28,7 @@ import { listJobs } from "./jobs.ts";
 import type { JobRecord } from "../core/contracts.ts";
 
 export { abortExtraction, extractionStatuses, type ExtractionPhase, type RunningExtraction } from "../agent/subagents/extraction.ts";
+export { practiceStatuses, type PracticePhase, type RunningPractice } from "../agent/subagents/practice-pipeline.ts";
 export { chatStore } from "../store/chats.ts";
 
 /** A running sub-agent job, joined with its chat's title for the dock.
@@ -54,6 +56,16 @@ export interface ActivityExtraction {
 	startedAt: number;
 }
 
+/** A live practice run in the dock's feed — mirrors ActivityExtraction
+ *  (kind names which pipeline half: generation or grading). */
+export interface ActivityPractice {
+	id: string;
+	kind: "generation" | "grading";
+	title: string;
+	phase: PracticePhase;
+	startedAt: number;
+}
+
 /** The dock's whole world in one payload: every running process, every view.
  *  Jobs are RUNNING-ONLY — finished jobs belong to their chat's transcript;
  *  the blob disappears when the process ends. Cost math is NOT done here:
@@ -65,7 +77,12 @@ export interface ActivityExtraction {
  *  graph changed underneath me" (a merge landed, a deletion purged) and
  *  refetch clusters/layout. Reads never move it; the DELETE response
  *  returns the same stamp. */
-export function activityFeed(): { jobs: ActivityJob[]; extractions: ActivityExtraction[]; graphRevision: number } {
+export function activityFeed(): {
+	jobs: ActivityJob[];
+	extractions: ActivityExtraction[];
+	practice: ActivityPractice[];
+	graphRevision: number;
+} {
 	const chats = chatStore.listChats();
 	const limits = catalogContextLimits();
 	const jobs: ActivityJob[] = [];
@@ -93,11 +110,19 @@ export function activityFeed(): { jobs: ActivityJob[]; extractions: ActivityExtr
 		phase: run.phase,
 		startedAt: run.startedAt,
 	}));
+	const practice: ActivityPractice[] = practiceStatuses().map((row) => ({
+		id: row.setId,
+		kind: row.kind,
+		title: row.label,
+		phase: row.phase,
+		startedAt: row.startedAt,
+	}));
 	// oldest-first on last activity: the stable blob order (ISO strings sort chronologically)
 	jobs.sort((a, b) => a.updatedAt.localeCompare(b.updatedAt));
 	return {
 		jobs,
 		extractions: extractions.sort((a, b) => a.startedAt - b.startedAt),
+		practice: practice.sort((a, b) => a.startedAt - b.startedAt),
 		graphRevision: graphRevision(),
 	};
 }