From cf0ec4a2f014bd8e1dbac21609741c5f4decedba Mon Sep 17 00:00:00 2001
From: amosblomqvist <amosblomqvist@gmail.com>
Date: Tue, 29 Sep 2026 21:54:32 +0300
Subject: [PATCH] =?UTF-8?q?practice=20UI=20round=20=E2=80=94=20top=20bars?=
 =?UTF-8?q?=20+=20sidebar=20reopen,=20one-attempt=20per-problem=20submit?=
 =?UTF-8?q?=20with=20instant=20reveal,=20score-only=20grading=20(owner=202?=
 =?UTF-8?q?026-09-29)?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 README.md                                   |   2 +-
 app/api/practice/sets/[id]/answers/route.ts |   5 +-
 components/practice-exam.tsx                | 648 ++++++++++++--------
 components/practice-list.tsx                | 446 ++++++++------
 docs/architecture.md                        |  12 +-
 next-env.d.ts                               |   4 +-
 src/agent/subagents/practice-pipeline.ts    |  25 +-
 src/agent/subagents/practice.ts             |  30 +-
 src/core/contracts/practice.ts              |  20 +-
 src/store/practice.ts                       |  30 +-
 tests/practice-agents.test.ts               |  18 +-
 tests/practice-pipeline.test.ts             |  32 +-
 tests/practice-store.test.ts                |  22 +-
 tests/render-practice.test.tsx              |  71 ++-
 14 files changed, 811 insertions(+), 554 deletions(-)

diff --git a/README.md b/README.md
index 530368f..48beb78 100644
--- a/README.md
+++ b/README.md
@@ -156,7 +156,7 @@ data/                           chats/ · graph/ (six ledgers + positions/source
 
 **The knowledge graph (two channels, one writer).** The write channel: the extraction pipeline — extractor (LLM: sees only the session, rendered as readable markdown by the shared `core/session-markdown.ts` engine — propositions as true statements, `follows`/`supports` edges with verbatim evidence; fully trusted, graph-blind) → auditor (LLM, an agentic loop that never sees the source: explores the existing graph through `find` / `list_sessions` / `list_propositions` tools, stamps each proposition with an identity verdict — link to an existing node (equivalence bias: paraphrases merge) or create — and may draw bridging edges between existing nodes and the new batch) → merger (`mergeFindings`, deterministic: applies the verdicts, link-appends phrasings/provenance, resolves and dedupes edges, checkpoints coverage) → layout settle. No quiz outcomes or understanding assessments live in the graph (2026-09-27 cleanup); practice (`/practice`) consumes the graph as feedback-only problem sets and writes nothing back. Triggered when a chat's **uncovered tokens** (message-view fingerprints, `coverage.jsonl`) cross `graph.extractionChunkTokens` (a settings knob, default 4096, floor 500 — read fresh per turn); failure checkpoints nothing, the next trigger re-runs. The same pipeline serves the **notes front door** (`POST /api/graph/import`: any `*.md`/`*.txt` becomes a source; re-imports are idempotent by path hash). The read channel: `GET /api/graph` derives the snapshot from the ledgers — a pure read; the home view is a hand-rolled Canvas 2D renderer (one rAF loop, dirty-flag idle, d3-zoom camera, zoom-gated labels, cluster hulls) over a d3-force layout, with server-persisted render settings and drag-committed positions. Clusters are **birth-session groupings**: a node joins the cluster of the session that birthed it (a chat, or an imported notes file as a file-kind session), derived at read — no embedding pass, no naming pass. The teacher reaches the graph on its own terms through the gated prober tools (`list_sessions` / `list_propositions`, the `agent.graphTools` setting) — there is no automatic context injection.
 
-**Practice (problem sets).** The graph's `follows`-edges become reasoning chains; the `/practice` creation dialog picks a birth-session cluster (the graph view's own groups) and freezes its propositions + chains into a self-contained `ProblemSet`. Three named-level axes steer generation (ladder rung 0–4, cue distance 0–2, Theory|Application — never a number to interpolate; defaults Direct exercise · Adjacent context · Theory). A partitioner agent covers every chain exactly once, one generator per partition writes problems against the owner's problem-engineering framework (commit-before-pose: statement + solution + rubric together), and grading is **strengthening, not assessment** — one grader per answer, verdict (`solid`/`partial`/`missed`) + feedback, post-grade reveal, nothing ever written back to the graph. Runs are registry-backed background jobs on the activity dock (no steer, never wakes the teacher); sets live in `data/practice`, crash-swept on boot.
+**Practice (problem sets).** The graph's `follows`-edges become reasoning chains; the `/practice` creation dialog picks a birth-session cluster (the graph view's own groups) and freezes its propositions + chains into a self-contained `ProblemSet`. Three named-level axes steer generation (ladder rung 0–4, cue distance 0–2, Theory|Application — never a number to interpolate; defaults Direct exercise · Adjacent context · Theory). A partitioner agent covers every chain exactly once, one generator per partition writes problems against the owner's problem-engineering framework (commit-before-pose: statement + solution + rubric together), and grading is **strengthening, not assessment** — one attempt per problem with its own submit button, instant solution/rubric reveal, then a score 0–10 with brief reasoning landing live; nothing ever written back to the graph. Runs are registry-backed background jobs on the activity dock (no steer, never wakes the teacher); sets live in `data/practice`, crash-swept on boot.
 
 **Dictation.** Optional speech-to-text: the server mints short-lived Deepgram tokens; audio streams browser→Deepgram over WebSocket, never through the server.
 
diff --git a/app/api/practice/sets/[id]/answers/route.ts b/app/api/practice/sets/[id]/answers/route.ts
index c6c3475..2e54636 100644
--- a/app/api/practice/sets/[id]/answers/route.ts
+++ b/app/api/practice/sets/[id]/answers/route.ts
@@ -2,8 +2,9 @@
  * 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).
+ * 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";
 
diff --git a/components/practice-exam.tsx b/components/practice-exam.tsx
index 0a87f76..dd5954a 100644
--- a/components/practice-exam.tsx
+++ b/components/practice-exam.tsx
@@ -1,282 +1,438 @@
 "use client";
 
 /**
- * The exam page (practice slice 5): one problem set, numbered problems,
- * markdown statements, a textarea + dictation per problem (the bar
- * renders only on the FOCUSED box — thinking out loud is the primary
- * answering mode), one submit for the set, and the post-grade reveal
- * (verdict chip, feedback, model solution, rubric) under the box.
+ * The exam page (practice slice 5, one-attempt redesign 2026-09-29):
+ * one problem set, numbered problems, markdown statements, a textarea +
+ * dictation per problem (the bar renders only on the FOCUSED box —
+ * thinking out loud is the primary answering mode). ONE ATTEMPT: each
+ * problem has its OWN submit button; once submitted the box locks and
+ * the MODEL SOLUTION reveals instantly (rubric collapsed by default).
+ * The grade (score 0–10 + brief reasoning) lands via the poll and
+ * updates live — no reload.
  *
- * DISPLAY-SEAM MATH HEALING: statements/solutions/rubrics/feedback ride
+ * TOP BAR (owner, UI round 2026-09-29): the chat pattern — an h-15
+ * lh-drag header in flow above the scroller, the sidebar reopen toggle
+ * first (it clears the traffic lights via .lh-closed-toggle), the set
+ * title truncating beside it. The levels + status stay in the body.
+ *
+ * DISPLAY-SEAM MATH HEALING: statements/solutions/rubrics/reasoning ride
  * the same streaming-args parse as quiz/ask strings — restoreMathEscapes
  * heals them at render (the same helper the tool-part seam uses).
  *
  * POLLING: 2s while the set isn't ready (stubs → filled), and while a
- * grading run is live for this set (activity feed's practice rows) with
- * answered-but-ungraded problems outstanding. A settled page goes quiet
- * (a dropped grade terminates honestly: no live row → no poll).
+ * grading run is live for this set (activity feed practice rows are
+ * keyed setId:grade:problemId — the LIVE rows name exactly which
+ * problems' grades are pending). A settled page goes quiet; a dropped
+ * grade shows "grade interrupted" honestly.
  */
 
 import { useCallback, useEffect, useRef, useState } from "react";
-import type { GradeVerdict, Problem, ProblemSet } from "@/src/core";
+import type { Problem, ProblemSet } from "@/src/core";
 import { CUE_LEVELS, LADDER_RUNGS, PRESENTATIONS } from "@/src/core";
 import { restoreMathEscapes } from "@/src/core";
 import { MessageResponse } from "@/components/ai-elements/message";
 import { BrailleSpinner } from "@/components/braille-spinner";
 import { DictationBar, useDictation } from "@/components/dictation";
-
-/** The verdict chip's tone — plain, no invented color language. */
-export function verdictClass(verdict: GradeVerdict): string {
-	if (verdict === "solid") return "bg-green-500/15 text-green-500";
-	if (verdict === "partial") return "bg-amber-500/15 text-amber-600 dark:text-amber-400";
-	return "bg-destructive/15 text-destructive";
-}
+import { SidebarToggle } from "@/components/sidebar";
 
 /** One answerable problem: textarea + focus-gated dictation bar. */
 export function ProblemBox({
-	problem,
-	draft,
-	onDraft,
+  problem,
+  draft,
+  onDraft,
 }: {
-	problem: Pick<Problem, "id">;
-	draft: string;
-	onDraft: (text: string) => void;
+  problem: Pick<Problem, "id">;
+  draft: string;
+  onDraft: (text: string) => void;
 }) {
-	const [focused, setFocused] = useState(false);
-	// The dictation appends into THIS box only (per-box instance).
-	const dictation = useDictation({
-		append: (text) => onDraft(text),
-	});
-	return (
-		<div className="flex flex-col gap-1.5" data-testid={`problem-box-${problem.id}`}>
-			<textarea
-				data-testid={`answer-${problem.id}`}
-				value={draft}
-				rows={5}
-				placeholder="Think out loud — dictation or typing, both fine."
-				onChange={(e) => onDraft(e.target.value)}
-				onFocus={() => setFocused(true)}
-				onBlur={() => setFocused(false)}
-				className="w-full resize-y rounded-lg border bg-background px-3 py-2 text-sm outline-none focus-visible:ring-1 focus-visible:ring-ring"
-			/>
-			{focused && <DictationBar dictation={dictation} />}
-		</div>
-	);
+  const [focused, setFocused] = useState(false);
+  // The dictation appends into THIS box only (per-box instance).
+  const dictation = useDictation({
+    append: (text) => onDraft(text),
+  });
+  return (
+    <div
+      className="flex flex-col gap-1.5"
+      data-testid={`problem-box-${problem.id}`}
+    >
+      <textarea
+        data-testid={`answer-${problem.id}`}
+        value={draft}
+        rows={5}
+        placeholder="Think out loud — dictation or typing, both fine."
+        onChange={(e) => onDraft(e.target.value)}
+        onFocus={() => setFocused(true)}
+        onBlur={() => setFocused(false)}
+        className="w-full resize-y rounded-lg border bg-background px-3 py-2 text-sm outline-none focus-visible:ring-1 focus-visible:ring-ring"
+      />
+      {focused && <DictationBar dictation={dictation} />}
+    </div>
+  );
 }
 
 /** The exam page's pure body — exported for SSR pins. */
 export function PracticeExamBody({
-	set,
-	drafts,
-	onDraft,
-	onSubmit,
-	submitting,
-	submitError,
-	grading,
+  set,
+  drafts,
+  onDraft,
+  onSubmit,
+  submittingId,
+  submitErrors,
+  liveGradeIds,
 }: {
-	set: ProblemSet;
-	drafts: Record<string, string>;
-	onDraft: (problemId: string, text: string) => void;
-	onSubmit: () => void;
-	submitting: boolean;
-	submitError: string | null;
-	grading: boolean;
+  set: ProblemSet;
+  drafts: Record<string, string>;
+  onDraft: (problemId: string, text: string) => void;
+  /** Per-problem submit (owner 2026-09-29): ONE attempt per problem. */
+  onSubmit: (problemId: string) => void;
+  /** The problem whose submit POST is in flight. */
+  submittingId: string | null;
+  /** Per-problem submit failures, keyed by problem id. */
+  submitErrors: Record<string, string>;
+  /** Problems whose grade rows are LIVE (the poll's activity feed). */
+  liveGradeIds: ReadonlySet<string>;
 }) {
-	const answerable = set.problems.filter((p) => !p.grade);
-	const anyDraft = answerable.some((p) => (drafts[p.id] ?? p.answer ?? "") !== "");
-	return (
-		<div className="h-dvh overflow-y-auto" data-testid="practice-exam-scroll">
-			<div className="mx-auto flex w-full max-w-3xl flex-col gap-6 p-6" data-testid="practice-exam">
-			<div className="flex flex-col gap-1">
-				<h1 className="font-title text-3xl tracking-tight">{set.title}</h1>
-				<p className="text-xs text-muted-foreground/80" data-testid="practice-exam-levels">
-					{LADDER_RUNGS[set.params.ladderRung].name} · {CUE_LEVELS[set.params.cueDistance].name} ·{" "}
-					{PRESENTATIONS[set.params.presentation].name}
-				</p>
-				<p className="text-sm text-muted-foreground" data-testid="practice-exam-status">
-					{set.status === "partitioning" && "Partitioning the chains…"}
-					{set.status === "generating" && `Generating — ${set.problems.filter((p) => p.status === "ready").length}/${set.problems.length} problems ready`}
-					{set.status === "error" && (set.error ?? "Something went wrong")}
-					{set.status === "ready" &&
-						(grading ? "Grading your answers…" : `${set.problems.length} problems · ${set.problems.filter((p) => p.grade).length} graded`)}
-				</p>
-			</div>
+  return (
+    <div className="flex h-dvh">
+      <div className="flex min-w-0 flex-1 flex-col">
+        {/* The top bar (owner, UI round 2026-09-29): the new-session
+				    pattern — h-15, lh-drag (the Electron window-drag surface, so
+				    the traffic lights never cover content), the sidebar reopen
+				    toggle first, the set title truncating beside it. */}
+        <header className="lh-drag flex h-15 items-center gap-3 border-b border-border px-3">
+          <SidebarToggle />
+          <div
+            className="min-w-0 flex-1 truncate font-title text-3xl tracking-tight"
+            data-testid="practice-exam-title"
+          >
+            {set.title}
+          </div>
+        </header>
+        <div className="relative flex min-h-0 flex-1">
+          <div
+            className="h-full min-w-0 flex-1 overflow-y-auto"
+            data-testid="practice-exam-scroll"
+          >
+            <div
+              className="mx-auto flex w-full max-w-3xl flex-col gap-6 p-6"
+              data-testid="practice-exam"
+            >
+              <div className="flex flex-col gap-1">
+                <p
+                  className="text-xs text-muted-foreground/80"
+                  data-testid="practice-exam-levels"
+                >
+                  {LADDER_RUNGS[set.params.ladderRung].name} ·{" "}
+                  {CUE_LEVELS[set.params.cueDistance].name} ·{" "}
+                  {PRESENTATIONS[set.params.presentation].name}
+                </p>
+                <p
+                  className="text-sm text-muted-foreground"
+                  data-testid="practice-exam-status"
+                >
+                  {set.status === "partitioning" && "Partitioning the chains…"}
+                  {set.status === "generating" &&
+                    `Generating — ${set.problems.filter((p) => p.status === "ready").length}/${set.problems.length} problems ready`}
+                  {set.status === "error" &&
+                    (set.error ?? "Something went wrong")}
+                  {set.status === "ready" &&
+                    (liveGradeIds.size > 0
+                      ? "Grading your answers…"
+                      : `${set.problems.length} problems · ${set.problems.filter((p) => p.grade).length} graded`)}
+                </p>
+              </div>
 
-			{set.problems.map((problem, i) => (
-				<section key={problem.id} className="rounded-xl border bg-card p-4" data-testid={`problem-${problem.id}`}>
-					<h2 className="mb-2 text-xs font-medium uppercase tracking-wide text-muted-foreground">Problem {i + 1}</h2>
-					{problem.status === "generating" ? (
-						// The stub: propositions NEVER surface (never-announce law).
-						<div className="flex items-center gap-2 text-sm text-muted-foreground" data-testid={`generating-${problem.id}`}>
-							<BrailleSpinner className="size-4" />
-							Generating problem…
-						</div>
-					) : problem.status === "error" ? (
-						<p className="text-sm text-destructive" data-testid={`problem-error-${problem.id}`}>
-							This problem failed to generate{problem.error ? ` — ${problem.error}` : ""}.
-						</p>
-					) : (
-						<>
-							<div className="lh-prose text-sm">
-								<MessageResponse mode="static">{restoreMathEscapes(problem.statement)}</MessageResponse>
-							</div>
-							{problem.grade ? (
-								// Graded: the answer read-only, the reveal below.
-								<div className="mt-4 flex flex-col gap-3">
-									<textarea
-										data-testid={`answer-${problem.id}`}
-										value={problem.answer ?? ""}
-										readOnly
-										rows={5}
-										className="w-full resize-y rounded-lg border bg-muted/40 px-3 py-2 text-sm text-muted-foreground"
-									/>
-									<div className="rounded-lg border bg-background p-3" data-testid={`reveal-${problem.id}`}>
-										<div className="mb-2 flex items-center gap-2">
-											<span className={`rounded px-1.5 py-0.5 text-xs font-medium uppercase ${verdictClass(problem.grade.verdict)}`}>
-												{problem.grade.verdict}
-											</span>
-										</div>
-										<div className="lh-prose text-sm" data-testid={`feedback-${problem.id}`}>
-											<MessageResponse mode="static">{restoreMathEscapes(problem.grade.feedback)}</MessageResponse>
-										</div>
-										<div className="mt-3 text-xs uppercase tracking-wide text-muted-foreground">Model solution</div>
-										<div className="lh-prose text-sm" data-testid={`solution-${problem.id}`}>
-											<MessageResponse mode="static">{restoreMathEscapes(problem.solution)}</MessageResponse>
-										</div>
-										<div className="mt-3 text-xs uppercase tracking-wide text-muted-foreground">Rubric</div>
-										<div className="lh-prose text-sm" data-testid={`rubric-${problem.id}`}>
-											<MessageResponse mode="static">{restoreMathEscapes(problem.rubric)}</MessageResponse>
-										</div>
-									</div>
-								</div>
-							) : (
-								// Answerable: the box (graded problems lock above).
-								<div className="mt-4">
-									<ProblemBox problem={problem} draft={drafts[problem.id] ?? problem.answer ?? ""} onDraft={(text) => onDraft(problem.id, text)} />
-								</div>
-							)}
-						</>
-					)}
-				</section>
-			))}
-
-			{set.status === "ready" && answerable.length > 0 && (
-				<div className="flex flex-col items-start gap-2">
-					<button
-						type="button"
-						data-testid="practice-submit"
-						onClick={onSubmit}
-						disabled={!anyDraft || submitting}
-						className="rounded-md bg-primary px-4 py-2 text-sm font-medium text-primary-foreground transition-colors hover:bg-primary/90 disabled:opacity-40"
-					>
-						{submitting ? "Submitting…" : "Submit answers"}
-					</button>
-					{submitError && (
-						<p data-testid="practice-submit-error" className="text-sm text-destructive">
-							{submitError}
-						</p>
-					)}
-				</div>
-			)}
-			</div>
-		</div>
-	);
+              {set.problems.map((problem, i) => (
+                <section
+                  key={problem.id}
+                  className="rounded-xl border bg-card p-4"
+                  data-testid={`problem-${problem.id}`}
+                >
+                  <h2 className="mb-2 text-xs font-medium uppercase tracking-wide text-muted-foreground">
+                    Problem {i + 1}
+                  </h2>
+                  {problem.status === "generating" ? (
+                    // The stub: propositions NEVER surface (never-announce law).
+                    <div
+                      className="flex items-center gap-2 text-sm text-muted-foreground"
+                      data-testid={`generating-${problem.id}`}
+                    >
+                      <BrailleSpinner className="size-4" />
+                      Generating problem…
+                    </div>
+                  ) : problem.status === "error" ? (
+                    <p
+                      className="text-sm text-destructive"
+                      data-testid={`problem-error-${problem.id}`}
+                    >
+                      This problem failed to generate
+                      {problem.error ? ` — ${problem.error}` : ""}.
+                    </p>
+                  ) : (
+                    <>
+                      <div className="lh-prose text-sm">
+                        <MessageResponse mode="static">
+                          {restoreMathEscapes(problem.statement)}
+                        </MessageResponse>
+                      </div>
+                      {problem.answer === undefined ? (
+                        // ANSWERABLE (owner 2026-09-29): the box + its OWN submit
+                        // button — one attempt, submitted the moment it's clicked.
+                        <div className="flex flex-col items-start gap-2">
+                          <div className="w-full">
+                            <ProblemBox
+                              problem={problem}
+                              draft={drafts[problem.id] ?? ""}
+                              onDraft={(text) => onDraft(problem.id, text)}
+                            />
+                          </div>
+                          <button
+                            type="button"
+                            data-testid={`practice-submit-${problem.id}`}
+                            onClick={() => onSubmit(problem.id)}
+                            disabled={
+                              set.status !== "ready" ||
+                              (drafts[problem.id] ?? "").trim() === "" ||
+                              submittingId !== null
+                            }
+                            className="rounded-md bg-primary px-4 py-2 text-sm font-medium text-primary-foreground transition-colors hover:bg-primary/90 disabled:opacity-40"
+                          >
+                            {submittingId === problem.id
+                              ? "Submitting…"
+                              : "Submit answer"}
+                          </button>
+                          {submitErrors[problem.id] && (
+                            <p
+                              data-testid={`practice-submit-error-${problem.id}`}
+                              className="text-sm text-destructive"
+                            >
+                              {submitErrors[problem.id]}
+                            </p>
+                          )}
+                        </div>
+                      ) : (
+                        // SUBMITTED (owner 2026-09-29): the answer locks, the
+                        // model solution reveals INSTANTLY, the rubric stays
+                        // collapsed, and the grade lands live when it lands.
+                        <div className="mt-4 flex flex-col gap-3">
+                          <textarea
+                            data-testid={`answer-${problem.id}`}
+                            value={problem.answer}
+                            readOnly
+                            rows={5}
+                            className="w-full resize-y rounded-lg border bg-muted/40 px-3 py-2 text-sm text-muted-foreground"
+                          />
+                          <div
+                            className="rounded-lg border bg-background p-3"
+                            data-testid={`reveal-${problem.id}`}
+                          >
+                            {problem.grade ? (
+                              <div className="flex flex-col gap-1.5">
+                                <div className="flex items-baseline gap-2">
+                                  <span
+                                    data-testid={`grade-${problem.id}`}
+                                    className="font-mono text-sm font-medium"
+                                  >
+                                    {problem.grade.score}/10
+                                  </span>
+                                </div>
+                                <div
+                                  className="lh-prose text-sm"
+                                  data-testid={`reasoning-${problem.id}`}
+                                >
+                                  <MessageResponse mode="static">
+                                    {restoreMathEscapes(
+                                      problem.grade.reasoning,
+                                    )}
+                                  </MessageResponse>
+                                </div>
+                              </div>
+                            ) : liveGradeIds.has(problem.id) ? (
+                              <div
+                                className="flex items-center gap-2 text-sm text-muted-foreground"
+                                data-testid={`grading-${problem.id}`}
+                              >
+                                <BrailleSpinner className="size-4" />
+                                Grading…
+                              </div>
+                            ) : (
+                              <p
+                                className="text-sm text-muted-foreground"
+                                data-testid={`grade-interrupted-${problem.id}`}
+                              >
+                                Grade interrupted — the answer stands.
+                              </p>
+                            )}
+                            <div className="mt-3 text-xs uppercase tracking-wide text-muted-foreground">
+                              Model solution
+                            </div>
+                            <div
+                              className="lh-prose text-sm"
+                              data-testid={`solution-${problem.id}`}
+                            >
+                              <MessageResponse mode="static">
+                                {restoreMathEscapes(problem.solution)}
+                              </MessageResponse>
+                            </div>
+                            <details
+                              className="mt-3"
+                              data-testid={`rubric-${problem.id}`}
+                            >
+                              <summary className="cursor-pointer select-none text-xs uppercase tracking-wide text-muted-foreground">
+                                Rubric
+                              </summary>
+                              <div className="mt-2 lh-prose text-sm">
+                                <MessageResponse mode="static">
+                                  {restoreMathEscapes(problem.rubric)}
+                                </MessageResponse>
+                              </div>
+                            </details>
+                          </div>
+                        </div>
+                      )}
+                    </>
+                  )}
+                </section>
+              ))}
+            </div>
+          </div>
+        </div>
+      </div>
+    </div>
+  );
 }
 
 export function PracticeExam({ initial }: { initial: ProblemSet }) {
-	const [set, setSet] = useState<ProblemSet>(initial);
-	const [drafts, setDrafts] = useState<Record<string, string>>({});
-	const [submitting, setSubmitting] = useState(false);
-	const [submitError, setSubmitError] = useState<string | null>(null);
-	const [gradingLive, setGradingLive] = useState(false);
-	const mounted = useRef(true);
-	useEffect(() => {
-		mounted.current = true;
-		return () => {
-			mounted.current = false;
-		};
-	}, []);
+  const [set, setSet] = useState<ProblemSet>(initial);
+  const [drafts, setDrafts] = useState<Record<string, string>>({});
+  const [submittingId, setSubmittingId] = useState<string | null>(null);
+  const [submitErrors, setSubmitErrors] = useState<Record<string, string>>({});
+  // Which problems' grade rows are LIVE (activity feed) — drives the
+  // per-problem "Grading…" spinners and the status line.
+  const [liveGradeIds, setLiveGradeIds] = useState<Set<string>>(new Set());
+  // True from a successful submit until the feed shows no live grade
+  // rows for this set — keeps the poll alive across refetches.
+  const [gradingLive, setGradingLive] = useState(false);
+  const mounted = useRef(true);
+  useEffect(() => {
+    mounted.current = true;
+    return () => {
+      mounted.current = false;
+    };
+  }, []);
 
-	const refetch = useCallback(async () => {
-		try {
-			const res = await fetch(`/api/practice/sets/${initial.id}`, { cache: "no-store" });
-			if (!res.ok) return;
-			const d = (await res.json()) as { set: ProblemSet };
-			if (mounted.current) setSet(d.set);
-		} catch {
-			// transient poll failures keep the last snapshot
-		}
-	}, [initial.id]);
+  const refetch = useCallback(async () => {
+    try {
+      const res = await fetch(`/api/practice/sets/${initial.id}`, {
+        cache: "no-store",
+      });
+      if (!res.ok) return;
+      const d = (await res.json()) as { set: ProblemSet };
+      if (mounted.current) setSet(d.set);
+    } catch {
+      // transient poll failures keep the last snapshot
+    }
+  }, [initial.id]);
 
-	// The poll: while not ready (generation), or while a grading run is
-	// live for this set with outstanding ungraded answers. The activity
-	// feed is the grading-liveness truth — a dropped grade (no live row)
-	// settles the page instead of polling forever.
-	const pendingGrade = set.problems.some((p) => p.answer && !p.grade);
-	const needsPoll = set.status !== "ready" || (gradingLive && pendingGrade);
-	useEffect(() => {
-		if (!needsPoll) return;
-		let stopped = false;
-		const tick = async () => {
-			await refetch();
-			try {
-				const res = await fetch("/api/activity", { cache: "no-store" });
-				if (!res.ok) return;
-				const feed = (await res.json()) as { practice?: Array<{ id: string; kind: string }> };
-				if (!stopped && mounted.current) {
-					setGradingLive((feed.practice ?? []).some((row) => row.id === initial.id));
-				}
-			} catch {
-				// keep the last liveness read
-			}
-		};
-		void tick();
-		const t = setInterval(() => void tick(), 2000);
-		return () => {
-			stopped = true;
-			clearInterval(t);
-		};
-	}, [needsPoll, refetch, initial.id]);
+  // The poll: while not ready (generation), or while a grading run is
+  // live for this set with outstanding ungraded answers. The activity
+  // feed's practice rows are ROW-KEYED (setId:grade:problemId) — the
+  // live rows name exactly which grades are pending; a dropped grade
+  // (no live row) settles the page instead of polling forever.
+  const pendingGrade = set.problems.some(
+    (p) => p.answer !== undefined && !p.grade,
+  );
+  const needsPoll = set.status !== "ready" || (gradingLive && pendingGrade);
+  useEffect(() => {
+    if (!needsPoll) return;
+    let stopped = false;
+    const tick = async () => {
+      await refetch();
+      try {
+        const res = await fetch("/api/activity", { cache: "no-store" });
+        if (!res.ok) return;
+        const feed = (await res.json()) as {
+          practice?: Array<{ id: string; kind: string }>;
+        };
+        if (!stopped && mounted.current) {
+          const prefix = `${initial.id}:grade:`;
+          const pids = (feed.practice ?? [])
+            .filter((row) => row.id.startsWith(prefix))
+            .map((row) => row.id.slice(prefix.length));
+          setLiveGradeIds(new Set(pids));
+          setGradingLive(pids.length > 0);
+        }
+      } catch {
+        // keep the last liveness read
+      }
+    };
+    void tick();
+    const t = setInterval(() => void tick(), 2000);
+    return () => {
+      stopped = true;
+      clearInterval(t);
+    };
+  }, [needsPoll, refetch, initial.id]);
 
-	const submit = useCallback(async () => {
-		if (submitting) return;
-		const answers = set.problems
-			.filter((p) => !p.grade)
-			.map((p) => ({ problemId: p.id, text: drafts[p.id] ?? p.answer ?? "" }))
-			.filter((a) => a.text.trim() !== "");
-		if (answers.length === 0) return;
-		setSubmitting(true);
-		setSubmitError(null);
-		try {
-			const res = await fetch(`/api/practice/sets/${set.id}/answers`, {
-				method: "POST",
-				headers: { "content-type": "application/json" },
-				body: JSON.stringify({ answers }),
-			});
-			if (!res.ok) {
-				const body = (await res.json().catch(() => ({}))) as { error?: string };
-				setSubmitError(body.error ?? `Submit failed (${res.status})`);
-				setSubmitting(false);
-				return;
-			}
-			setSubmitting(false);
-			setGradingLive(true); // grades land via the poll
-			await refetch();
-		} catch {
-			setSubmitError("Submit failed — network error. Try again.");
-			setSubmitting(false);
-		}
-	}, [submitting, set, drafts, refetch]);
+  // ONE attempt per problem (owner 2026-09-29): the submit posts THAT
+  // problem's answer alone; the server refuses a second submission
+  // forever after. On success the box locks (answer persisted) and the
+  // reveal shows instantly; the grade arrives via the poll.
+  const submit = useCallback(
+    async (problemId: string) => {
+      if (submittingId !== null) return;
+      const p = set.problems.find((q) => q.id === problemId);
+      if (!p || p.answer !== undefined) return; // done problems never resubmit
+      const text = drafts[problemId] ?? "";
+      if (text.trim() === "") return;
+      setSubmittingId(problemId);
+      setSubmitErrors((prev) => {
+        const next = { ...prev };
+        delete next[problemId];
+        return next;
+      });
+      try {
+        const res = await fetch(`/api/practice/sets/${set.id}/answers`, {
+          method: "POST",
+          headers: { "content-type": "application/json" },
+          body: JSON.stringify({ answers: [{ problemId, text }] }),
+        });
+        if (!res.ok) {
+          const body = (await res.json().catch(() => ({}))) as {
+            error?: string;
+          };
+          setSubmitErrors((prev) => ({
+            ...prev,
+            [problemId]: body.error ?? `Submit failed (${res.status})`,
+          }));
+          setSubmittingId(null);
+          return;
+        }
+        setSubmittingId(null);
+        setGradingLive(true); // the grade lands via the poll
+        await refetch();
+      } catch {
+        setSubmitErrors((prev) => ({
+          ...prev,
+          [problemId]: "Submit failed — network error. Try again.",
+        }));
+        setSubmittingId(null);
+      }
+    },
+    [submittingId, set, drafts, refetch],
+  );
 
-	return (
-		<PracticeExamBody
-			set={set}
-			drafts={drafts}
-			onDraft={(problemId, text) => setDrafts((prev) => ({ ...prev, [problemId]: text }))}
-			onSubmit={() => void submit()}
-			submitting={submitting}
-			submitError={submitError}
-			grading={gradingLive && pendingGrade}
-		/>
-	);
+  return (
+    <PracticeExamBody
+      set={set}
+      drafts={drafts}
+      onDraft={(problemId, text) =>
+        setDrafts((prev) => ({ ...prev, [problemId]: text }))
+      }
+      onSubmit={(problemId) => void submit(problemId)}
+      submittingId={submittingId}
+      submitErrors={submitErrors}
+      liveGradeIds={liveGradeIds}
+    />
+  );
 }
diff --git a/components/practice-list.tsx b/components/practice-list.tsx
index d996afa..06d2c09 100644
--- a/components/practice-list.tsx
+++ b/components/practice-list.tsx
@@ -13,229 +13,279 @@ import { useCallback, useEffect, useState } from "react";
 import { useRouter } from "next/navigation";
 import { createPortal } from "react-dom";
 import { PlusIcon, TrashIcon } from "lucide-react";
+import { SidebarToggle } from "@/components/sidebar";
 import type { ProblemSet } from "@/src/core";
 import { PracticeDialog } from "@/components/practice-dialog";
 
 /** A set's status word — plain and honest, no invented progress. */
 export function setStatusWord(set: Pick<ProblemSet, "status">): string {
-	return set.status === "partitioning" ? "partitioning" : set.status === "generating" ? "generating" : set.status;
+  return set.status === "partitioning"
+    ? "partitioning"
+    : set.status === "generating"
+      ? "generating"
+      : set.status;
 }
 
 /** The list's pure body — exported for SSR pins. Rows are buttons
  *  (click-through); the delete affordance is a nested icon button. */
 export function PracticeListBody({
-	sets,
-	onOpen,
-	onDelete,
-	onNew,
+  sets,
+  onOpen,
+  onDelete,
+  onNew,
 }: {
-	sets: ProblemSet[];
-	onOpen: (id: string) => void;
-	onDelete: (set: ProblemSet) => void;
-	onNew: () => void;
+  sets: ProblemSet[];
+  onOpen: (id: string) => void;
+  onDelete: (set: ProblemSet) => void;
+  onNew: () => void;
 }) {
-	return (
-		<div className="h-dvh overflow-y-auto" data-testid="practice-list-scroll">
-			<div className="mx-auto flex w-full max-w-3xl flex-col gap-3 p-6" data-testid="practice-list">
-			<div className="flex items-center justify-between">
-				<h1 className="font-title text-3xl tracking-tight">Practice</h1>
-				<button
-					type="button"
-					data-testid="practice-new"
-					onClick={onNew}
-					className="flex items-center gap-1.5 rounded-md border px-3 py-1.5 text-sm transition-colors hover:bg-accent"
-				>
-					<PlusIcon className="size-3.5" />
-					New problem set
-				</button>
-			</div>
+  return (
+    <div className="flex h-dvh">
+      <div className="flex min-w-0 flex-1 flex-col">
+        {/* The top bar (owner, UI round 2026-09-29): the new-session
+				    pattern — h-15, lh-drag (the Electron window-drag surface),
+				    the sidebar reopen toggle first, "Practice" beside it, the
+				    page's one action at the right edge (lh-no-drag — it must
+				    stay clickable inside the drag band). */}
+        <header className="lh-drag flex h-15 items-center gap-3 border-b border-border px-3">
+          <SidebarToggle />
+          <div className="min-w-0 flex-1 truncate font-title text-3xl tracking-tight">
+            Practice
+          </div>
+          <button
+            type="button"
+            data-testid="practice-new"
+            onClick={onNew}
+            className="lh-no-drag flex shrink-0 items-center gap-1.5 rounded-md border px-3 py-1.5 text-sm transition-colors hover:bg-accent"
+          >
+            <PlusIcon className="size-3.5" />
+            New problem set
+          </button>
+        </header>
+        <div className="relative flex min-h-0 flex-1">
+          <div
+            className="h-full min-w-0 flex-1 overflow-y-auto"
+            data-testid="practice-list-scroll"
+          >
+            <div
+              className="mx-auto flex w-full max-w-3xl flex-col gap-3 p-6"
+              data-testid="practice-list"
+            >
+              {sets.length === 0 && (
+                <div
+                  className="rounded-xl border bg-card p-6 text-sm text-muted-foreground"
+                  data-testid="practice-empty"
+                >
+                  No problem sets yet — create one from a session.
+                </div>
+              )}
 
-			{sets.length === 0 && (
-				<div className="rounded-xl border bg-card p-6 text-sm text-muted-foreground" data-testid="practice-empty">
-					No problem sets yet — create one from a session.
-				</div>
-			)}
-
-			<div className="flex flex-col gap-2">
-				{sets.map((set) => {
-					const ready = set.problems.filter((p) => p.status === "ready").length;
-					const graded = set.problems.filter((p) => p.grade).length;
-					return (
-						<div key={set.id} className="flex items-stretch gap-1">
-							<button
-								type="button"
-								data-testid={`practice-row-${set.id}`}
-								onClick={() => onOpen(set.id)}
-								className="flex flex-1 items-center justify-between gap-4 rounded-xl border bg-card px-4 py-3 text-left transition-colors hover:bg-accent/50"
-							>
-								<span className="min-w-0">
-									<span className="block truncate font-medium">{set.title}</span>
-									<span className="block text-xs text-muted-foreground">
-										{set.createdAt.slice(0, 10)} · {set.problems.length > 0 ? `${ready}/${set.problems.length} problems` : "no problems yet"}
-										{graded > 0 ? ` · ${graded} graded` : ""}
-									</span>
-								</span>
-								<span
-									data-testid={`practice-status-${set.id}`}
-									className={`shrink-0 text-xs uppercase tracking-wide ${
-										set.status === "error" ? "text-destructive" : "text-muted-foreground"
-									}`}
-								>
-									{setStatusWord(set)}
-								</span>
-							</button>
-							<button
-								type="button"
-								data-testid={`practice-delete-${set.id}`}
-								aria-label={`Delete ${set.title}`}
-								onClick={() => onDelete(set)}
-								className="flex items-center rounded-xl border px-3 text-muted-foreground/60 transition-colors hover:bg-accent hover:text-foreground"
-							>
-								<TrashIcon className="size-4" />
-							</button>
-						</div>
-					);
-				})}
-			</div>
-		</div>
-		</div>
-	);
+              <div className="flex flex-col gap-2">
+                {sets.map((set) => {
+                  const ready = set.problems.filter(
+                    (p) => p.status === "ready",
+                  ).length;
+                  const graded = set.problems.filter((p) => p.grade).length;
+                  return (
+                    <div key={set.id} className="flex items-stretch gap-1">
+                      <button
+                        type="button"
+                        data-testid={`practice-row-${set.id}`}
+                        onClick={() => onOpen(set.id)}
+                        className="flex flex-1 items-center justify-between gap-4 rounded-xl border bg-card px-4 py-3 text-left transition-colors hover:bg-accent/50"
+                      >
+                        <span className="min-w-0">
+                          <span className="block truncate font-medium">
+                            {set.title}
+                          </span>
+                          <span className="block text-xs text-muted-foreground">
+                            {set.createdAt.slice(0, 10)} ·{" "}
+                            {set.problems.length > 0
+                              ? `${ready}/${set.problems.length} problems`
+                              : "no problems yet"}
+                            {graded > 0 ? ` · ${graded} graded` : ""}
+                          </span>
+                        </span>
+                        <span
+                          data-testid={`practice-status-${set.id}`}
+                          className={`shrink-0 text-xs uppercase tracking-wide ${
+                            set.status === "error"
+                              ? "text-destructive"
+                              : "text-muted-foreground"
+                          }`}
+                        >
+                          {setStatusWord(set)}
+                        </span>
+                      </button>
+                      <button
+                        type="button"
+                        data-testid={`practice-delete-${set.id}`}
+                        aria-label={`Delete ${set.title}`}
+                        onClick={() => onDelete(set)}
+                        className="flex items-center rounded-xl border px-3 text-muted-foreground/60 transition-colors hover:bg-accent hover:text-foreground"
+                      >
+                        <TrashIcon className="size-4" />
+                      </button>
+                    </div>
+                  );
+                })}
+              </div>
+            </div>
+          </div>
+        </div>
+      </div>
+    </div>
+  );
 }
 
 /** The delete confirm — the delete-session dialog's shape (no mode
  *  checkbox: a set has no preserve-graph question). Pure body + portal
  *  wrapper. */
 export function DeleteSetBody({
-	title,
-	busy,
-	failure,
-	onClose,
-	onRun,
+  title,
+  busy,
+  failure,
+  onClose,
+  onRun,
 }: {
-	title: string;
-	busy: boolean;
-	failure: string | null;
-	onClose: () => void;
-	onRun: () => void;
+  title: string;
+  busy: boolean;
+  failure: string | null;
+  onClose: () => void;
+  onRun: () => void;
 }) {
-	return (
-		<div
-			role="dialog"
-			aria-modal="true"
-			aria-label="Delete problem set"
-			data-testid="delete-set-dialog"
-			onClick={(e) => e.stopPropagation()}
-			className="w-[32rem] max-w-[calc(100vw-2rem)] rounded-xl border bg-card p-5 shadow-xl"
-		>
-			<h2 className="font-title text-2xl tracking-tight text-destructive">Delete problem set?</h2>
-			<p className="mt-2 font-mono text-sm">{title}</p>
-			<p className="mt-3 text-sm text-muted-foreground">
-				The set and its problems are removed. Nothing in the graph or your sessions changes.
-			</p>
-			{failure && (
-				<p data-testid="delete-set-error" className="mt-3 text-sm text-destructive">
-					{failure}
-				</p>
-			)}
-			<div className="mt-5 flex justify-end gap-2">
-				<button
-					type="button"
-					onClick={onClose}
-					disabled={busy}
-					className="rounded-md px-3 py-1.5 text-sm text-muted-foreground transition-colors hover:bg-accent hover:text-foreground"
-				>
-					Cancel
-				</button>
-				<button
-					type="button"
-					data-testid="delete-set-run"
-					onClick={onRun}
-					disabled={busy}
-					className="rounded-md bg-destructive px-3 py-1.5 text-sm font-medium text-destructive-foreground transition-colors hover:bg-destructive/90 disabled:opacity-40"
-				>
-					{busy ? "Deleting…" : "Delete"}
-				</button>
-			</div>
-		</div>
-	);
+  return (
+    <div
+      role="dialog"
+      aria-modal="true"
+      aria-label="Delete problem set"
+      data-testid="delete-set-dialog"
+      onClick={(e) => e.stopPropagation()}
+      className="w-[32rem] max-w-[calc(100vw-2rem)] rounded-xl border bg-card p-5 shadow-xl"
+    >
+      <h2 className="font-title text-2xl tracking-tight text-destructive">
+        Delete problem set?
+      </h2>
+      <p className="mt-2 font-mono text-sm">{title}</p>
+      <p className="mt-3 text-sm text-muted-foreground">
+        The set and its problems are removed. Nothing in the graph or your
+        sessions changes.
+      </p>
+      {failure && (
+        <p
+          data-testid="delete-set-error"
+          className="mt-3 text-sm text-destructive"
+        >
+          {failure}
+        </p>
+      )}
+      <div className="mt-5 flex justify-end gap-2">
+        <button
+          type="button"
+          onClick={onClose}
+          disabled={busy}
+          className="rounded-md px-3 py-1.5 text-sm text-muted-foreground transition-colors hover:bg-accent hover:text-foreground"
+        >
+          Cancel
+        </button>
+        <button
+          type="button"
+          data-testid="delete-set-run"
+          onClick={onRun}
+          disabled={busy}
+          className="rounded-md bg-destructive px-3 py-1.5 text-sm font-medium text-destructive-foreground transition-colors hover:bg-destructive/90 disabled:opacity-40"
+        >
+          {busy ? "Deleting…" : "Delete"}
+        </button>
+      </div>
+    </div>
+  );
 }
 
-export function PracticeListPage({ initialSets }: { initialSets: ProblemSet[] }) {
-	const router = useRouter();
-	const [sets, setSets] = useState<ProblemSet[]>(initialSets);
-	const [creating, setCreating] = useState(false);
-	const [deleting, setDeleting] = useState<ProblemSet | null>(null);
-	const [deleteBusy, setDeleteBusy] = useState(false);
-	const [deleteFailure, setDeleteFailure] = useState<string | null>(null);
+export function PracticeListPage({
+  initialSets,
+}: {
+  initialSets: ProblemSet[];
+}) {
+  const router = useRouter();
+  const [sets, setSets] = useState<ProblemSet[]>(initialSets);
+  const [creating, setCreating] = useState(false);
+  const [deleting, setDeleting] = useState<ProblemSet | null>(null);
+  const [deleteBusy, setDeleteBusy] = useState(false);
+  const [deleteFailure, setDeleteFailure] = useState<string | null>(null);
 
-	const refresh = useCallback(async () => {
-		try {
-			const res = await fetch("/api/practice/sets", { cache: "no-store" });
-			if (!res.ok) return;
-			const d = (await res.json()) as { sets: ProblemSet[] };
-			setSets(d.sets);
-		} catch {
-			// a transient failure on the poll keeps the last snapshot
-		}
-	}, []);
+  const refresh = useCallback(async () => {
+    try {
+      const res = await fetch("/api/practice/sets", { cache: "no-store" });
+      if (!res.ok) return;
+      const d = (await res.json()) as { sets: ProblemSet[] };
+      setSets(d.sets);
+    } catch {
+      // a transient failure on the poll keeps the last snapshot
+    }
+  }, []);
 
-	// The reveal poll: while any set is partitioning/generating, statuses
-	// live-update; a settled list goes quiet.
-	const anyRunning = sets.some((s) => s.status === "partitioning" || s.status === "generating");
-	useEffect(() => {
-		if (!anyRunning) return;
-		const t = setInterval(() => void refresh(), 2000);
-		return () => clearInterval(t);
-	}, [anyRunning, refresh]);
+  // The reveal poll: while any set is partitioning/generating, statuses
+  // live-update; a settled list goes quiet.
+  const anyRunning = sets.some(
+    (s) => s.status === "partitioning" || s.status === "generating",
+  );
+  useEffect(() => {
+    if (!anyRunning) return;
+    const t = setInterval(() => void refresh(), 2000);
+    return () => clearInterval(t);
+  }, [anyRunning, refresh]);
 
-	const runDelete = useCallback(async () => {
-		if (!deleting || deleteBusy) return;
-		setDeleteBusy(true);
-		setDeleteFailure(null);
-		try {
-			const res = await fetch(`/api/practice/sets/${deleting.id}`, { method: "DELETE" });
-			if (!res.ok) {
-				const body = (await res.json().catch(() => ({}))) as { error?: string };
-				setDeleteFailure(body.error ?? `Delete failed (${res.status})`);
-				setDeleteBusy(false);
-				return;
-			}
-			setDeleting(null);
-			setDeleteBusy(false);
-			await refresh();
-		} catch {
-			setDeleteFailure("Delete failed — network error. Try again.");
-			setDeleteBusy(false);
-		}
-	}, [deleting, deleteBusy, refresh]);
+  const runDelete = useCallback(async () => {
+    if (!deleting || deleteBusy) return;
+    setDeleteBusy(true);
+    setDeleteFailure(null);
+    try {
+      const res = await fetch(`/api/practice/sets/${deleting.id}`, {
+        method: "DELETE",
+      });
+      if (!res.ok) {
+        const body = (await res.json().catch(() => ({}))) as { error?: string };
+        setDeleteFailure(body.error ?? `Delete failed (${res.status})`);
+        setDeleteBusy(false);
+        return;
+      }
+      setDeleting(null);
+      setDeleteBusy(false);
+      await refresh();
+    } catch {
+      setDeleteFailure("Delete failed — network error. Try again.");
+      setDeleteBusy(false);
+    }
+  }, [deleting, deleteBusy, refresh]);
 
-	return (
-		<>
-			<PracticeListBody
-				sets={sets}
-				onOpen={(id) => router.push(`/practice/${id}`)}
-				onDelete={(set) => setDeleting(set)}
-				onNew={() => setCreating(true)}
-			/>
-			{creating && <PracticeDialog onClose={() => setCreating(false)} />}
-			{deleting &&
-				createPortal(
-					<div
-						className="fixed inset-0 z-50 flex items-center justify-center bg-background/80"
-						onClick={() => {
-							if (!deleteBusy) setDeleting(null);
-						}}
-					>
-						<DeleteSetBody
-							title={deleting.title}
-							busy={deleteBusy}
-							failure={deleteFailure}
-							onClose={() => setDeleting(null)}
-							onRun={() => void runDelete()}
-						/>
-					</div>,
-					document.body,
-				)}
-		</>
-	);
+  return (
+    <>
+      <PracticeListBody
+        sets={sets}
+        onOpen={(id) => router.push(`/practice/${id}`)}
+        onDelete={(set) => setDeleting(set)}
+        onNew={() => setCreating(true)}
+      />
+      {creating && <PracticeDialog onClose={() => setCreating(false)} />}
+      {deleting &&
+        createPortal(
+          <div
+            className="fixed inset-0 z-50 flex items-center justify-center bg-background/80"
+            onClick={() => {
+              if (!deleteBusy) setDeleting(null);
+            }}
+          >
+            <DeleteSetBody
+              title={deleting.title}
+              busy={deleteBusy}
+              failure={deleteFailure}
+              onClose={() => setDeleting(null)}
+              onRun={() => void runDelete()}
+            />
+          </div>,
+          document.body,
+        )}
+    </>
+  );
 }
diff --git a/docs/architecture.md b/docs/architecture.md
index dcf826d..d5269b6 100644
--- a/docs/architecture.md
+++ b/docs/architecture.md
@@ -152,7 +152,7 @@ flowchart TB
 - `contracts/jobs.ts` — the ack-and-steer protocol: job records, steer message builders, deterministic steer ids, usage accumulation
 - `contracts/probe.ts` — probe assessment + the shared zod schema
 - `contracts/models.ts` — client-safe model-catalog shapes
-- `contracts/practice.ts` — problem sets, reasoning chains, params, grade verdicts
+- `contracts/practice.ts` — problem sets, reasoning chains, params, grade scores
 
 ---
 
@@ -234,7 +234,7 @@ flowchart TB
     end
 
     subgraph PRAC["PRACTICE — problem sets (owns data/practice)"]
-        PPART["practice pipeline — partitioner → one generator per problem · one grader per answer<br/>(feedback-only; never steers the teacher)"]
+        PPART["practice pipeline — partitioner → one generator per problem · one grader per answer<br/>(score-only; never steers the teacher)"]
         PDATA["problem sets — data/practice/*.json"]
     end
 
@@ -368,7 +368,7 @@ flowchart TB
 
 ## 7. Practice — strengthening, not assessment (owner ruling 2026-09-29)
 
-Practice turns the graph into problem sets the learner reasons through out loud. The purpose ruling first: this is **strengthening, not assessment**. Grades are feedback for the learner — a verdict, an explanation, a look at the model solution — and nothing else. Grading writes nothing to the graph, no understanding levels exist anywhere, and the vision doc's exam machinery (scores, streaks, spaced repetition over failure rates) stays parked. A set exercises what the learner already met; it certifies nothing.
+Practice turns the graph into problem sets the learner reasons through out loud. The purpose ruling first: this is **strengthening, not assessment**. Grades are feedback for the learner — a score, a brief justification, a look at the model solution — and nothing else. Grading writes nothing to the graph, no understanding levels exist anywhere, and the vision doc's exam machinery (scores, streaks, spaced repetition over failure rates) stays parked. A set exercises what the learner already met; it certifies nothing.
 
 **The chain model.** Practice sees a node selection as **reasoning chains**: the selection's `follows`-edges grouped by conclusion (`chainsForSelection`, `src/core/practice.ts`). A chain is `premises → conclusion` — one per conclusion node, a singleton for an edge-less node; premise-only nodes belong to no chain. The grouping is a **bijection with the follows-edge set** (`chainsToGraph` is its exact inverse, round-trip test-pinned) — no chain exists that isn't the edges, no edge that isn't in a chain. **Supports edges are invisible to practice** (owner ruling: supports are grounding, not reasoning steps). The partition must cover every chain **exactly once** — a true partition; duplicates fail validation exactly like gaps (owner amendment 2026-09-29: variety accumulates ACROSS sets, never within one — the at-least-once doctrine is dead). `chainCoverage` is the soundness check: only `missing` fails a partition, `duplicated` is informational.
 
@@ -378,11 +378,11 @@ Practice turns the graph into problem sets the learner reasons through out loud.
 
 **Two-stage generation.** One **partitioner** agent reads the chains plus the three NAMED-LEVEL parameters and submits the true partition; each partition becomes one problem's target. Then **one generator agent per problem**: its prompt carries the problem-engineering framework verbatim (the owner's doctrine — the three distances, the search-to-solution axis, the rung ladder, reverse/discriminate/probe-the-premises, the standing prohibitions, the formatting doctrine — full Markdown, LaTeX math, fenced code, tables/lists; prose-only renderings of structured content are a defect), **YOUR TARGET** (the assigned chains echoed verbatim — the echo law: the submit's chain set must equal the assignment exactly), and **THE FULL SET** (the whole selection: outside propositions are supporting material the generator may draw on with minimal use and maximal focus; the never-announce law covers ALL propositions). The submit is commit-before-pose — statement, solution, and rubric arrive together (the same sycophancy mitigation the quiz/explain mechanic uses); a problem never exists without its pre-written answer. Generators run in parallel (a process-wide 3-permit semaphore shared with grading) with per-problem failure isolation: one bad problem errors alone; the set still reaches `ready`. **Dedup across sets**: each generator also sees the problems of the ≤5 most recent sets sharing a node, so situations don't repeat between sets; within a set, parallel generators can't see each other — accepted for V1 (owner ruling).
 
-**Grading is feedback-only.** Submitting answers fires one **grader** job per answered problem: the grader sees the problem, the propositions its chains touch, the pre-written solution and rubric, and the learner's answer — never the full set (minimal, by ruling). It returns a verdict (`solid`/`partial`/`missed`) and feedback that names the failed recall and teaches the boundary. The verdict lands on the problem and the UI reveals it with the solution and rubric; the answer locks. Nothing reaches the graph, no level, no count, anywhere. A grader failure leaves the answer gradeless and re-submittable.
+**Grading is score-only (owner redesign, 2026-09-29).** ONE ATTEMPT: each problem has its own submit button; once submitted the answer persists and the problem is done — the route refuses re-submission forever after. The submit reveals INSTANTLY (no waiting on the grader): the answer locks read-only, the model solution shows, the rubric sits collapsed. Grading fires one **grader** job per answered problem — the grader sees the problem, the propositions its chains touch, the pre-written solution and rubric, and the learner's answer, never the full set (minimal, by ruling) — and returns an integer **score 0–10 plus one or two sentences of reasoning** (which rubric points were met or missed, which proposition failed to come to mind). The score lands on the problem via the page's 2s poll and updates live; grades never serialize set-wide (submitting B while A grades is fine — the shared pool bounds parallelism). Nothing reaches the graph, no level, no count, anywhere. A dropped grade leaves the answer standing with an honest “grade interrupted” line — one attempt, no re-submission.
 
-**The jobs pattern — registry, not JobRecords.** Practice runs are NOT Workbench jobs: no `JobStore` records, no steer messages, nothing ever wakes the teacher — a practice run isn't chat-scoped (a set outlives its birth session and has no lesson to re-enter; its result is itself, persisted in its own store and read by its own page). What it shares with the Workbench is the observability surface: a `globalThis` run registry (the module-instance idiom — `__lhPracticeRuns`) with PER-PROBLEM ROWS (owner ruling, 2026-09-29 — matching the extraction per-chunk pattern): `setId:partition` while the partitioner runs ("Partitioning — title"), then one `setId:gen:problemId` per problem ("queued"→"generating", label "Problem i/N — title"), and one `setId:grade:problemId` per graded answer ("queued"→"grading", "Grading i/N — title") — each row its OWN abort controller and its OWN usage accumulation; the row key IS the feed id (the dock dup-key law) and the abort target. ABORT ROUTES BY ROW SHAPE: a gen-row abort kills THAT problem only (siblings continue; the set still settles `ready` with one errored problem), a partition-row abort ends the whole run, a grade-row abort drops that grade (answer kept, re-submittable); set-level abort (delete) composes from row aborts plus the synchronous persisted marks. Model calls — partitioner included — run under the SHARED background-LLM semaphore (`bg-llm-semaphore.ts`): one process-wide pool of 3 permits for ALL background LLM jobs, extraction chunks included (total background LLM concurrency bounded at 3, whoever calls). A boot sweep marks orphaned `partitioning`/`generating` sets as `error "Interrupted (server restarted)"` — once per process, and only when the set's `updatedAt` heartbeat is >120s stale (a live run saves at every transition and is structurally never stamped; the guard trio closed a live-stamping bug from the first live test) — the job runner's crash-honesty at set grain. Store writes serialize behind a per-set mutex; the pipeline is the sole writer of `data/practice`.
+**The jobs pattern — registry, not JobRecords.** Practice runs are NOT Workbench jobs: no `JobStore` records, no steer messages, nothing ever wakes the teacher — a practice run isn't chat-scoped (a set outlives its birth session and has no lesson to re-enter; its result is itself, persisted in its own store and read by its own page). What it shares with the Workbench is the observability surface: a `globalThis` run registry (the module-instance idiom — `__lhPracticeRuns`) with PER-PROBLEM ROWS (owner ruling, 2026-09-29 — matching the extraction per-chunk pattern): `setId:partition` while the partitioner runs ("Partitioning — title"), then one `setId:gen:problemId` per problem ("queued"→"generating", label "Problem i/N — title"), and one `setId:grade:problemId` per graded answer ("queued"→"grading", "Grading i/N — title") — each row its OWN abort controller and its OWN usage accumulation; the row key IS the feed id (the dock dup-key law) and the abort target. ABORT ROUTES BY ROW SHAPE: a gen-row abort kills THAT problem only (siblings continue; the set still settles `ready` with one errored problem), a partition-row abort ends the whole run, a grade-row abort drops that grade (answer kept — one attempt, the problem stays done); set-level abort (delete) composes from row aborts plus the synchronous persisted marks. Model calls — partitioner included — run under the SHARED background-LLM semaphore (`bg-llm-semaphore.ts`): one process-wide pool of 3 permits for ALL background LLM jobs, extraction chunks included (total background LLM concurrency bounded at 3, whoever calls). A boot sweep marks orphaned `partitioning`/`generating` sets as `error "Interrupted (server restarted)"` — once per process, and only when the set's `updatedAt` heartbeat is >120s stale (a live run's 30s FILE watchdog keeps the heartbeat fresh even across dev's per-worker processes — the registry is not shared between them; the guard trio closed a live-stamping bug from the first live test) — the job runner's crash-honesty at set grain. Store writes serialize behind a per-set mutex; the pipeline is the sole writer of `data/practice`.
 
-**API + UI.** Creation is GRAPH-DOMAIN, not chat-domain (owner ruling 2026-09-29: "problem sets always take in nodes — graph objects"): `POST /api/practice/sets` takes `{nodeIds, params, title?}` ONLY — no chatId, no clusterId; the UI resolves a picked cluster to its member node ids and passes the cluster's label as the title. `GET /api/graph/clusters` serves the picker: the birth-session partition itself (`birthSessionPartition`, same ordering — size desc, ties by id) — EVERY group regardless of size (owner ruling, same evening: MIN_CLUSTER_SIZE is a hull-drawing rule; practice availability must not inherit a visual threshold), each as `{key, kind: "chat"|"notes", label, nodeIds, nodeCount}`; a cluster whose naming record is gone keeps `label: null` — honest, never guessed. 202 `{id}` with generation fire-and-forget; 400 empty selection (empty intersection with live nodes — the vanished-nodes edge) / bad params; 503 model/key refusal. `GET /api/practice/sets` · `GET/DELETE /api/practice/sets/[id]` (delete aborts live runs first) · `POST /api/practice/sets/[id]/answers` (202; 409 when not ready). Surfaces: `/practice` (the list — status/counts rows, delete confirm, the new-set dialog with the named-level controls (a 5-detent ladder slider, a 3-detent cue slider, a Theory|Application toggle — each showing the level's name + definition) and the cluster picker — the ONLY creation entry for now; the graph-view cluster entry comes later with the free-form selection UI) and `/practice/[id]` (the exam page — a levels line in the header, numbered problems, markdown statements with math healing at the display seam, a textarea + focus-gated dictation bar per problem, one Submit per set, the post-grade reveal). Entry: the sidebar's Practice nav row.
+**API + UI.** Creation is GRAPH-DOMAIN, not chat-domain (owner ruling 2026-09-29: "problem sets always take in nodes — graph objects"): `POST /api/practice/sets` takes `{nodeIds, params, title?}` ONLY — no chatId, no clusterId; the UI resolves a picked cluster to its member node ids and passes the cluster's label as the title. `GET /api/graph/clusters` serves the picker: the birth-session partition itself (`birthSessionPartition`, same ordering — size desc, ties by id) — EVERY group regardless of size (owner ruling, same evening: MIN_CLUSTER_SIZE is a hull-drawing rule; practice availability must not inherit a visual threshold), each as `{key, kind: "chat"|"notes", label, nodeIds, nodeCount}`; a cluster whose naming record is gone keeps `label: null` — honest, never guessed. 202 `{id}` with generation fire-and-forget; 400 empty selection (empty intersection with live nodes — the vanished-nodes edge) / bad params; 503 model/key refusal. `GET /api/practice/sets` · `GET/DELETE /api/practice/sets/[id]` (delete aborts live runs first) · `POST /api/practice/sets/[id]/answers` (202; 409 when not ready; 400 re-answering a submitted problem — one attempt). Surfaces: `/practice` (the list — the chat-pattern top bar with the sidebar reopen toggle and the New action at the right edge, status/counts rows, delete confirm, the new-set dialog with the named-level controls (a 5-detent ladder slider, a 3-detent cue slider, a Theory|Application toggle — each showing the level's name + definition) and the cluster picker — the ONLY creation entry for now; the graph-view cluster entry comes later with the free-form selection UI) and `/practice/[id]` (the exam page — the chat-pattern top bar, a levels + status line, numbered problems, markdown statements with math healing at the display seam, a textarea + focus-gated dictation bar per problem with its OWN Submit button — one attempt per problem, instant solution/rubric reveal, the score landing live). Entry: the sidebar's Practice nav row.
 
 **Model wiring.** Three roles — `partitioner`, `problemGenerator`, `grader` — all pinned to the **strong** slot (quality-critical, one settings edit from cheap) and in `BACKGROUND_MODEL_ROLES` (per-role overrides). The stage agents are single-submit loops on the shared `runSubmitAgent` seam (`submit-agent.ts`, extracted from extraction for exactly this): a `validate` hook turns a bad submit into a tool-input error the model retries against, within `maxTurns 4`; exhaustion fails the stage honestly (the set says so, the chains re-run cleanly on a new set).
 
diff --git a/next-env.d.ts b/next-env.d.ts
index ce4e94a..a419cbe 100644
--- a/next-env.d.ts
+++ b/next-env.d.ts
@@ -1,7 +1,7 @@
 /// <reference types="next" />
 /// <reference types="next/image-types/global" />
-import "./.next/types/routes.d.ts";
-import "./.next/types/root-params.d.ts";
+import "./.next/dev/types/routes.d.ts";
+import "./.next/dev/types/root-params.d.ts";
 
 // NOTE: This file should not be edited
 // see https://nextjs.org/docs/app/api-reference/config/typescript for more information.
diff --git a/src/agent/subagents/practice-pipeline.ts b/src/agent/subagents/practice-pipeline.ts
index 88e269d..f080aea 100644
--- a/src/agent/subagents/practice-pipeline.ts
+++ b/src/agent/subagents/practice-pipeline.ts
@@ -34,10 +34,12 @@
  * 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).
+ * ONE ATTEMPT PER PROBLEM (owner ruling 2026-09-29): a problem accepts
+ * a single submission — once `answer` is set the problem is done, the
+ * route refuses re-submission. Grades are per-problem: submitting
+ * another problem while one grades is fine (the shared LLM pool bounds
+ * parallelism); only the SAME problem's live grade row blocks (which
+ * the one-attempt rule already prevents client-side).
  */
 
 import type { GraphStore, PracticeStore } from "../../core/ports.ts";
@@ -476,8 +478,10 @@ export function createPracticePipeline(deps: PracticePipelineDeps) {
 		answers: Array<{ problemId: string; text: string }>,
 	): Promise<{ set: ProblemSet; done: Promise<void> }> {
 		agents.refuseIfStagesUnready(); // grading needs its engine — refuse BEFORE saving answers
-		for (const key of practiceRuns().keys()) {
-			if (key.startsWith(`${setId}:grade:`)) throw new BadAnswersError("a grading run is already in flight for this set");
+		for (const a of answers) {
+			if (practiceRuns().has(`${setId}:grade:${(a as { problemId?: unknown }).problemId}`)) {
+				throw new BadAnswersError("this problem's grade is already in flight");
+			}
 		}
 		const set = await withSetLock(setId, () => {
 			const cur = deps.practiceStore.getSet(setId);
@@ -488,7 +492,9 @@ export function createPracticePipeline(deps: PracticePipelineDeps) {
 				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`);
+				// ONE attempt (owner 2026-09-29): an existing answer ends the
+				// problem — graded or not, it is never re-submitted.
+				if (p.answer !== undefined) throw new BadAnswersError(`problem ${a.problemId} was already answered`);
 			}
 			for (const a of answers) {
 				const p = cur.problems.find((q) => q.id === a.problemId)!;
@@ -550,12 +556,13 @@ export function createPracticePipeline(deps: PracticePipelineDeps) {
 					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() };
+					p.grade = { score: graded.score, reasoning: graded.reasoning, gradedAt: new Date().toISOString() };
 					deps.practiceStore.saveSet(cur);
 				});
 			});
 		} catch (err) {
-			// Grading failure: the grade simply stays absent (re-submittable).
+			// Grading failure: the grade simply stays absent (the answer
+			// stands — one attempt; the UI shows "grade interrupted").
 			console.error(`[practice] grading failed for ${problemId}:`, isAbortLike(err) ? "aborted" : messageOf(err));
 		} finally {
 			practiceRuns().delete(row.key);
diff --git a/src/agent/subagents/practice.ts b/src/agent/subagents/practice.ts
index 45f7227..96d51b6 100644
--- a/src/agent/subagents/practice.ts
+++ b/src/agent/subagents/practice.ts
@@ -211,7 +211,7 @@ PARTITION DOCTRINE:
 
 OUTPUT — your entire deliverable is ONE submit_partition call: "partitions", a list of { chains: [ids] }, one entry per problem, together containing every input chain exactly once. No empty entries; no unknown ids; no problem without a real target relationship.`;
 
-export const GRADER_INSTRUCTIONS = `You are the grading stage of a learning application's practice system. One practice problem — built to strengthen the learner's recall of specific propositions — has been answered. Your job is FEEDBACK ONLY: verdict + what actually mattered. You are not assessing a person; you are coaching a recall.
+export const GRADER_INSTRUCTIONS = `You are the grading stage of a learning application's practice system. One practice problem — built to strengthen the learner's recall of specific propositions — has been answered. Your job is small and fast: an integer score and a one-or-two-sentence justification. You are not assessing a person; you are scoring a recall.
 
 You receive: the problem's statement; its pre-written MODEL SOLUTION and GRADING RUBRIC (committed before the learner ever saw the problem — they are the reference, not you); the propositions (names + statements) the problem was built to exercise; and the learner's ANSWER — often dictated thinking-out-loud prose. Extract the reasoning from the prose; grade the substance, never the form. Do not demand the solution's exact wording — the rubric names what actually matters; nothing else is graded.
 
@@ -219,18 +219,14 @@ JUDGE AGAINST THE REFERENCE:
 - Work the rubric points: which are met, which are missed, which are half-met in the answer's own terms.
 - Where the answer diverges from the model solution, ask whether the divergence is a different-but-valid route (the rubric decides) or a wrong turn.
 
-NAME THE FAILED RECALL: when something is missed, identify WHICH proposition failed to come to mind — or came to mind in a wrong or incomplete form. That is the actionable diagnosis; say it plainly.
+THE SCORE (one integer, 0–10):
+- 9–10: the targeted recall(s) happened — the answer meets the rubric's essentials. Peripheral gaps do not lower it.
+- 5–8: some of the target came to mind; the answer is materially incomplete or partly wrong.
+- 0–4: the targeted proposition(s) did not come to mind — the answer is empty or on the wrong track.
 
-TEACH THE BOUNDARY: feedback should locate the boundary — what would have made the answer right, where the wrong path breaks and why. Not "incorrect"; the reason it is incorrect, in one or two tight paragraphs.
+The reasoning is plain prose, one or two sentences: which rubric points were met or missed and, when something failed, WHICH proposition failed to come to mind. Mathematics is LaTeX — inline as \\(…\\), display as \\[…\\] (a bare $ is literal currency); no headers, no lists — minimal is the standard.
 
-THE VERDICT (exactly one):
-- "solid": the targeted recall(s) happened — the answer meets the rubric's essentials. Peripheral gaps do not lower it.
-- "partial": some of the target came to mind; the answer is materially incomplete or partly wrong.
-- "missed": the targeted proposition(s) did not come to mind — the answer is empty or on the wrong track.
-
-Feedback renders as full Markdown. Mathematics is always LaTeX — inline as \\(…\\), display as \\[…\\] on its own lines (a bare $ is literal currency). Inside math, LaTeX commands for symbols, not unicode stand-ins. Code in fenced blocks with a language tag, identifiers inline as \`code\`. Lists and tables wherever they carry structure; no headers — feedback is short-form, structure it with paragraphs and bold labels. Name the failed recall and teach the boundary in properly formatted prose, not plain text.
-
-OUTPUT — your entire deliverable is ONE submit_grade call: "verdict" and "feedback" (non-empty; the boundary-teaching text above).`;
+OUTPUT — your entire deliverable is ONE submit_grade call: "score" (integer 0–10) and "reasoning" (non-empty, brief).`;
 
 // ─── schemas + fills ─────────────────────────────────────────────────────────
 
@@ -250,8 +246,8 @@ const problemSchema = Type.Object({
 type ProblemSubmit = Static<typeof problemSchema>;
 
 const gradeSchema = Type.Object({
-	verdict: Type.Union([Type.Literal("solid"), Type.Literal("partial"), Type.Literal("missed")]),
-	feedback: Type.String({ minLength: 1 }),
+	score: Type.Integer({ minimum: 0, maximum: 10 }),
+	reasoning: Type.String({ minLength: 1 }),
 });
 type GradeSubmit = Static<typeof gradeSchema>;
 
@@ -364,8 +360,8 @@ export interface GraderInput {
 	signal?: AbortSignal;
 }
 export interface GraderOutput {
-	verdict: "solid" | "partial" | "missed";
-	feedback: string;
+	score: number;
+	reasoning: string;
 	log: PracticeStepLog;
 }
 
@@ -499,7 +495,7 @@ export function createPracticeAgents(deps: PracticeModels) {
 		const grade = await runSubmitAgent({
 			role: "grader",
 			toolName: "submit_grade",
-			toolDescription: "Submit the grade: verdict (solid | partial | missed) and non-empty feedback.",
+			toolDescription: "Submit the grade: an integer score 0-10 and brief non-empty reasoning.",
 			parameters: gradeSchema,
 			fill: (raw) => raw,
 			systemPrompt: GRADER_INSTRUCTIONS,
@@ -509,7 +505,7 @@ export function createPracticeAgents(deps: PracticeModels) {
 			onStep: stepLogger(log),
 			neverSubmitted: "the grader never submitted a grade",
 		});
-		return { verdict: grade.verdict, feedback: grade.feedback, log };
+		return { score: grade.score, reasoning: grade.reasoning, log };
 	}
 
 	return { refuseIfStagesUnready, runPartitioner, runProblemGenerator, runGrader };
diff --git a/src/core/contracts/practice.ts b/src/core/contracts/practice.ts
index 6bb193c..d17c52a 100644
--- a/src/core/contracts/practice.ts
+++ b/src/core/contracts/practice.ts
@@ -113,16 +113,16 @@ export type ProblemSetStatus = "partitioning" | "generating" | "ready" | "error"
  *  generator submits. */
 export type ProblemStatus = "generating" | "ready" | "error";
 
-/** The grader's three-level verdict (feedback-only; nothing derives from
- *  it — no understanding writes, owner 2026-09-29). */
-export type GradeVerdict = "solid" | "partial" | "missed";
-
-/** The grading job's deliverable, stored on the problem record. */
+/** The grading job's deliverable (owner, 2026-09-29 — one attempt per
+ * problem; the grader scores, it does not coach in prose): an integer
+ * score against the pre-written rubric plus a minimal justification.
+ * Nothing derives from it — no understanding writes. */
 export interface ProblemGrade {
-	verdict: GradeVerdict;
-	/** What actually mattered: the failed recall named, the boundary
-	 *  taught — against the pre-written solution + rubric. */
-	feedback: string;
+	/** 0–10, integer. */
+	score: number;
+	/** Why this score — one or two sentences: which rubric points were
+	 * met or missed, and which proposition failed to come to mind. */
+	reasoning: string;
 	gradedAt: string;
 }
 
@@ -151,7 +151,7 @@ export interface Problem {
 	/** The learner's answer, once submitted (dictation-first — thinking
 	 *  out loud is the primary answering mode). */
 	answer?: string;
-	/** The grading job's verdict, once it lands. */
+	/** The grader's score + reasoning, once it lands. */
 	grade?: ProblemGrade;
 }
 
diff --git a/src/store/practice.ts b/src/store/practice.ts
index 69375a9..a66e7c3 100644
--- a/src/store/practice.ts
+++ b/src/store/practice.ts
@@ -73,7 +73,21 @@ const isPropositions = (v: unknown): boolean => {
 
 const SET_STATUSES = new Set(["partitioning", "generating", "ready", "error"]);
 const PROBLEM_STATUSES = new Set(["generating", "ready", "error"]);
-const VERDICTS = new Set(["solid", "partial", "missed"]);
+function isGrade(g: unknown): boolean {
+	if (typeof g !== "object" || g === null) return false;
+	const v = g as Record<string, unknown>;
+	// Integer 0–10 + non-empty reasoning (one-attempt redesign, owner
+	// 2026-09-29: the grader scores; verdicts + prose feedback retired).
+	return (
+		typeof v.score === "number" &&
+		Number.isInteger(v.score) &&
+		v.score >= 0 &&
+		v.score <= 10 &&
+		typeof v.reasoning === "string" &&
+		v.reasoning.length > 0 &&
+		typeof v.gradedAt === "string"
+	);
+}
 
 const isProblem = (v: unknown): boolean => {
 	if (typeof v !== "object" || v === null) return false;
@@ -83,19 +97,7 @@ const isProblem = (v: unknown): boolean => {
 	if (typeof p.status !== "string" || !PROBLEM_STATUSES.has(p.status)) return false;
 	if (p.error !== undefined && typeof p.error !== "string") return false;
 	if (p.answer !== undefined && typeof p.answer !== "string") return false;
-	if (p.grade !== undefined) {
-		const g = p.grade as Record<string, unknown>;
-		if (
-			typeof g !== "object" ||
-			g === null ||
-			typeof g.verdict !== "string" ||
-			!VERDICTS.has(g.verdict) ||
-			typeof g.feedback !== "string" ||
-			typeof g.gradedAt !== "string"
-		) {
-			return false;
-		}
-	}
+	if (p.grade !== undefined && !isGrade(p.grade)) return false;
 	return true;
 };
 
diff --git a/tests/practice-agents.test.ts b/tests/practice-agents.test.ts
index 7d49128..35eec06 100644
--- a/tests/practice-agents.test.ts
+++ b/tests/practice-agents.test.ts
@@ -233,27 +233,27 @@ describe("runGrader", () => {
 		answer: "Well, if I'm arguing at all, I must own myself…",
 	};
 
-	it("returns the verdict + feedback with its step log", async () => {
+	it("returns the score + reasoning with its step log", async () => {
 		const agents = createPracticeAgents({
-			grader: submitModel("submit_grade", { verdict: "solid", feedback: "The recall happened." }),
+			grader: submitModel("submit_grade", { score: 9, reasoning: "The recall happened." }),
 		});
 		const out = await agents.runGrader(graderInput);
-		assert.equal(out.verdict, "solid");
-		assert.equal(out.feedback, "The recall happened.");
+		assert.equal(out.score, 9);
+		assert.equal(out.reasoning, "The recall happened.");
 		assert.ok(out.log.model);
 		assert.equal(out.log.steps.length, 1);
 	});
 
-	it("schema-rejects an off-union verdict and retries", async () => {
+	it("schema-rejects an out-of-range score and retries", async () => {
 		const agents = createPracticeAgents({
 			grader: retryModel(
 				"submit_grade",
-				{ verdict: "excellent", feedback: "…" },
-				{ verdict: "partial", feedback: "Half the target came to mind." },
+				{ score: 12, reasoning: "…" },
+				{ score: 6, reasoning: "Half the target came to mind." },
 			),
 		});
 		const out = await agents.runGrader(graderInput);
-		assert.equal(out.verdict, "partial");
+		assert.equal(out.score, 6);
 		assert.equal(out.log.steps.length, 2);
 	});
 
@@ -312,7 +312,7 @@ describe("formatting doctrine pins", () => {
 	it("GRADER_INSTRUCTIONS carries the formatting paragraph before the OUTPUT section", () => {
 		assert.ok(
 			GRADER_INSTRUCTIONS.includes(
-				"Feedback renders as full Markdown. Mathematics is always LaTeX — inline as \\(…\\), display as \\[…\\] on its own lines (a bare $ is literal currency). Inside math, LaTeX commands for symbols, not unicode stand-ins. Code in fenced blocks with a language tag, identifiers inline as `code`. Lists and tables wherever they carry structure; no headers — feedback is short-form, structure it with paragraphs and bold labels. Name the failed recall and teach the boundary in properly formatted prose, not plain text.",
+				"The reasoning is plain prose, one or two sentences: which rubric points were met or missed and, when something failed, WHICH proposition failed to come to mind. Mathematics is LaTeX — inline as \\(…\\), display as \\[…\\] (a bare $ is literal currency); no headers, no lists — minimal is the standard.",
 			),
 			"the exact grader paragraph",
 		);
diff --git a/tests/practice-pipeline.test.ts b/tests/practice-pipeline.test.ts
index e05dbc9..c3238db 100644
--- a/tests/practice-pipeline.test.ts
+++ b/tests/practice-pipeline.test.ts
@@ -152,7 +152,7 @@ function echoGenerator(count = 24, failTargets: string[] = []): PiEngine {
 	return fauxEngine(Array.from({ length: count }, () => factory));
 }
 
-/** A grader whose verdict encodes in the answer text ("solid" → solid). */
+/** A grader whose score encodes in the answer text ("solid" → 9, else 6). */
 function echoGrader(count: number): PiEngine {
 	const factory: FauxResponseStep = (context) => {
 		const answer = lastUserText(context as never).split("THE LEARNER'S ANSWER\n")[1] ?? "";
@@ -161,8 +161,8 @@ function echoGrader(count: number): PiEngine {
 				fauxToolCall(
 					"submit_grade",
 					{
-						verdict: answer.includes("solid") ? "solid" : "partial",
-						feedback: "The boundary.",
+						score: answer.includes("solid") ? 9 : 6,
+						reasoning: "Which rubric points were met.",
 					} as ToolCall["arguments"],
 					{ id: "grade-call" },
 				),
@@ -521,7 +521,7 @@ describe("createProblemSet (generation)", () => {
 		const gate = new Promise<void>((r) => (release = r));
 		// hold both grades at the model seam
 		const holdSteps: FauxResponseStep[] = Array.from({ length: 2 }, () => () =>
-			gate.then(() => fauxAssistantMessage([fauxToolCall("submit_grade", { verdict: "solid", feedback: "yes" } as ToolCall["arguments"], { id: "gr" })], { stopReason: "toolUse" })),
+			gate.then(() => fauxAssistantMessage([fauxToolCall("submit_grade", { score: 9, reasoning: "yes" } as ToolCall["arguments"], { id: "gr" })], { stopReason: "toolUse" })),
 		);
 		const f = fixture({
 			partitioner: partitionModel([{ chains: ["b"] }, { chains: ["c"] }]),
@@ -554,7 +554,7 @@ describe("createProblemSet (generation)", () => {
 		await sub.done;
 		assert.equal(practiceStatuses().length, 0);
 		const graded = f.practice.store.getSet(set.id)!;
-		assert.ok(graded.problems.every((p) => p.grade?.verdict === "solid"));
+		assert.ok(graded.problems.every((p) => p.grade?.score === 9));
 	});
 
 	it("abort ONE gen row: that problem dies alone, siblings complete, set reaches ready with one errored", async () => {
@@ -600,7 +600,7 @@ describe("createProblemSet (generation)", () => {
 		assert.equal(practiceStatuses().length, 0);
 	});
 
-	it("abort ONE grade row (queued): that grade drops (answer kept, re-submittable), sibling grade lands", async () => {
+	it("abort ONE grade row (queued): that grade drops (answer kept, one attempt — no re-submission), sibling grade lands", async () => {
 		const f = fixture({
 			partitioner: partitionModel([{ chains: ["b"] }, { chains: ["c"] }]),
 			problemGenerator: echoGenerator(2),
@@ -645,14 +645,18 @@ describe("createProblemSet (generation)", () => {
 		assert.equal(dropped.grade, undefined, "the aborted grade is absent");
 		assert.equal(dropped.answer, "first", "the answer is kept");
 		const other = graded.problems.find((p) => p.id !== victimId)!;
-		assert.equal(other.grade?.verdict, "partial", "the sibling grade landed (echoGrader: no 'solid' in its text)");
+		assert.equal(other.grade?.score, 6, "the sibling grade landed (echoGrader: no 'solid' in its text)");
 		assert.equal(practiceStatuses().length, 0);
 
-		// re-submittable: the dropped answer grades on a second submit
-		const resub = await pipeline.submitAnswers(set.id, [{ problemId: victimId, text: "retry answer" }]);
-		await resub.done;
-		const retried = f.practice.store.getSet(set.id)!;
-		assert.equal(retried.problems.find((p) => p.id === victimId)!.grade?.verdict, "partial", "the retry grades (echoGrader verdict)");
+		// ONE attempt (owner 2026-09-29): the dropped grade's answer
+		// stands — re-submission is refused, the problem is done.
+		await assert.rejects(
+			() => pipeline.submitAnswers(set.id, [{ problemId: victimId, text: "retry answer" }]),
+			/was already answered/,
+		);
+		const after = f.practice.store.getSet(set.id)!;
+		assert.equal(after.problems.find((p) => p.id === victimId)!.grade, undefined, "still no grade — one attempt");
+		assert.equal(after.problems.find((p) => p.id === victimId)!.answer, "first");
 
 		rh1();
 		rh2();
@@ -772,8 +776,8 @@ describe("submitAnswers (grading)", () => {
 		const final = f.practice.store.getSet(set.id)!;
 		const g1 = final.problems.find((p) => p.id === p1.id)!.grade;
 		const g2 = final.problems.find((p) => p.id === p2.id)!.grade;
-		assert.ok(g1 && g1.verdict === "solid", "verdict encodes from the answer text");
-		assert.ok(g2 && g2.verdict === "partial");
+		assert.ok(g1 && g1.score === 9, "score encodes from the answer text");
+		assert.ok(g2 && g2.score === 6);
 		assert.ok(g1!.gradedAt >= NOW);
 		assert.equal(practiceStatuses().length, 0, "the grading row clears");
 
diff --git a/tests/practice-store.test.ts b/tests/practice-store.test.ts
index 054e24b..1401a63 100644
--- a/tests/practice-store.test.ts
+++ b/tests/practice-store.test.ts
@@ -79,13 +79,13 @@ describe("the practice store", () => {
 			rubric: "- names the performative contradiction",
 			status: "ready",
 			answer: "Because…",
-			grade: { verdict: "solid", feedback: "Named it.", gradedAt: "2026-09-29T13:00:00.000Z" },
+			grade: { score: 9, reasoning: "Named it.", gradedAt: "2026-09-29T13:00:00.000Z" },
 		});
 		set.status = "ready";
 		practiceStore.saveSet(set);
 		const reread = practiceStore.getSet(set.id);
 		assert.equal(reread?.status, "ready");
-		assert.equal(reread?.problems[0]?.grade?.verdict, "solid");
+		assert.equal(reread?.problems[0]?.grade?.score, 9);
 	});
 
 	it("listSets returns createdAt-descending and skips corrupt/unparseable files", () => {
@@ -157,17 +157,21 @@ describe("isProblemSet", () => {
 		assert.ok(isProblemSet(minimal));
 	});
 
-	it("grade verdicts are the three-level union", () => {
-		const withGrade = (verdict: string): unknown => ({
+	it("grades are integer scores 0–10 with non-empty reasoning (one-attempt redesign)", () => {
+		const withGrade = (score: unknown, reasoning = "why"): unknown => ({
 			...init(),
 			id: "ps_valid",
 			problems: [
-				{ id: "pp_1", chains: [], statement: "", solution: "", rubric: "", status: "ready", grade: { verdict, feedback: "", gradedAt: "t" } },
+				{ id: "pp_1", chains: [], statement: "", solution: "", rubric: "", status: "ready", grade: { score, reasoning, gradedAt: "t" } },
 			],
 		});
-		assert.ok(isProblemSet(withGrade("solid")));
-		assert.ok(isProblemSet(withGrade("partial")));
-		assert.ok(isProblemSet(withGrade("missed")));
-		assert.ok(!isProblemSet(withGrade("excellent")));
+		assert.ok(isProblemSet(withGrade(0)));
+		assert.ok(isProblemSet(withGrade(10)));
+		assert.ok(!isProblemSet(withGrade(11)), "above the range");
+		assert.ok(!isProblemSet(withGrade(-1)), "below the range");
+		assert.ok(!isProblemSet(withGrade(7.5)), "fractional scores are refused");
+		assert.ok(!isProblemSet(withGrade("9")), "string scores are refused");
+		assert.ok(!isProblemSet(withGrade(9, "")), "empty reasoning is refused");
+		assert.ok(!isProblemSet({ ...init(), id: "ps_valid", problems: [{ id: "pp_1", chains: [], statement: "", solution: "", rubric: "", status: "ready", grade: { verdict: "solid", feedback: "legacy", gradedAt: "t" } }] }), "legacy verdict grades fail (wipe regime)");
 	});
 });
diff --git a/tests/render-practice.test.tsx b/tests/render-practice.test.tsx
index af065d2..5ecafbe 100644
--- a/tests/render-practice.test.tsx
+++ b/tests/render-practice.test.tsx
@@ -200,7 +200,7 @@ describe("PracticeListBody — the set list", () => {
 	it("graded count appears; empty list states it honestly", () => {
 		const s = set({
 			problems: [
-				readyProblem("pp_1", ["n3"], { grade: { verdict: "solid", feedback: "f", gradedAt: "2026-09-29T13:00:00.000Z" } }),
+				readyProblem("pp_1", ["n3"], { answer: "a", grade: { score: 9, reasoning: "r", gradedAt: "2026-09-29T13:00:00.000Z" } }),
 				readyProblem("pp_2", ["n1"]),
 			],
 		});
@@ -251,9 +251,9 @@ describe("PracticeExamBody — exam states", () => {
 		drafts: {} as Record<string, string>,
 		onDraft: () => {},
 		onSubmit: () => {},
-		submitting: false,
-		submitError: null as string | null,
-		grading: false,
+		submittingId: null as string | null,
+		submitErrors: {} as Record<string, string>,
+		liveGradeIds: new Set<string>(),
 	};
 
 	it("generating: numbered stubs with the placeholder — propositions NEVER surface", () => {
@@ -271,12 +271,19 @@ describe("PracticeExamBody — exam states", () => {
 		assert.ok(!html.includes("Each person owns themself"));
 		assert.ok(!html.includes('data-testid="answer-pp_1"'), "no answer box for a stub");
 		// No submit while generating.
-		assert.ok(!html.includes('data-testid="practice-submit"'));
+		assert.ok(!html.includes('data-testid="practice-submit-'));
 	});
 
-	it("the header carries the levels line (named levels, owner 2026-09-29)", () => {
+	it("the top bar carries the title + sidebar toggle; the body carries the levels line (owner, UI round 2026-09-29)", () => {
 		const s = set({ problems: [readyProblem("pp_1", ["n3"])] });
 		const html = renderToStaticMarkup(<PracticeExamBody set={s} {...examBase} />);
+		// The chat-pattern top bar: drag surface, toggle slot, truncating title.
+		assert.ok(html.includes("lh-drag"));
+		assert.ok(html.includes('aria-label="Open sidebar"'));
+		assert.ok(html.includes('data-testid="practice-exam-title"'));
+		assert.ok(html.includes("Ethics lesson"));
+		// The internal scroller (the sidebar stays fixed when this page scrolls).
+		assert.ok(html.includes('data-testid="practice-exam-scroll"'));
 		assert.ok(html.includes('data-testid="practice-exam-levels"'));
 		assert.ok(html.includes("Direct exercise · Adjacent context · Theory"), "the fixture's rung 2 / cue 1 / theory");
 	});
@@ -286,37 +293,67 @@ describe("PracticeExamBody — exam states", () => {
 		const gated = renderToStaticMarkup(<PracticeExamBody set={s} {...examBase} />);
 		assert.ok(gated.includes("self-ownership")); // markdown strong rendered
 		assert.ok(gated.includes('data-testid="answer-pp_1"'));
-		assert.ok(gated.includes('data-testid="practice-submit"'));
+		// PER-PROBLEM submit (owner 2026-09-29): the button lives under the
+		// box, gated on a draft; there is NO global submit anywhere.
+		assert.ok(gated.includes('data-testid="practice-submit-pp_1"'));
 		assert.ok(gated.includes('disabled=""'), "empty drafts — submit disabled");
 		const filled = renderToStaticMarkup(<PracticeExamBody set={s} {...examBase} drafts={{ pp_1: "because…" }} />);
-		assert.ok(!filled.includes('data-testid="practice-submit-error"'));
+		assert.ok(!filled.includes('disabled=""'), "a draft arms the submit");
+		assert.ok(!filled.includes('data-testid="practice-submit-error-pp_1"'));
 	});
 
-	it("graded: answer read-only, verdict chip + feedback + solution + rubric revealed", () => {
+	it("submitted + graded: answer read-only, score + reasoning + solution revealed, rubric collapsed", () => {
 		const s = set({
 			problems: [
 				readyProblem("pp_1", ["n3"], {
 					answer: "because arguing is intentional action",
-					grade: { verdict: "partial", feedback: "Half the target came to mind.", gradedAt: "2026-09-29T13:00:00.000Z" },
+					grade: { score: 6, reasoning: "Half the target came to mind.", gradedAt: "2026-09-29T13:00:00.000Z" },
 				}),
 				readyProblem("pp_2", ["n1"]),
 			],
 		});
 		const html = renderToStaticMarkup(<PracticeExamBody set={s} {...examBase} />);
-		// The locked answer.
+		// The locked answer — one attempt, done.
 		assert.ok(html.includes("because arguing is intentional action"));
-		assert.ok(/readOnly/.test(html), "the graded answer is read-only");
-		// The reveal.
-		assert.ok(html.includes('data-testid="reveal-pp_1"'));
-		assert.ok(html.includes("partial"));
-		assert.ok(html.includes('data-testid="feedback-pp_1"'));
+		assert.ok(/readOnly/.test(html), "the submitted answer is read-only");
+		assert.ok(!html.includes('data-testid="practice-submit-pp_1"'), "no re-submission");
+		// The grade: mono score + brief reasoning.
+		assert.ok(html.includes('data-testid="grade-pp_1"'));
+		assert.ok(html.includes("6/10"));
+		assert.ok(html.includes('data-testid="reasoning-pp_1"'));
 		assert.ok(html.includes("Half the target came to mind."));
+		// The instant reveal.
+		assert.ok(html.includes('data-testid="reveal-pp_1"'));
 		assert.ok(html.includes('data-testid="solution-pp_1"'));
 		assert.ok(html.includes("The model solution."));
+		// The rubric rides a collapsed <details> (owner 2026-09-29).
+		assert.ok(html.includes("<details"));
+		assert.ok(!html.includes("<details open"), "collapsed by default");
 		assert.ok(html.includes('data-testid="rubric-pp_1"'));
 		assert.ok(html.includes("names self-ownership"));
-		// Ungraded sibling stays answerable.
+		// Unanswered sibling stays answerable.
 		assert.ok(html.includes('data-testid="answer-pp_2"'));
+		assert.ok(html.includes('data-testid="practice-submit-pp_2"'));
+	});
+
+	it("submitted, grade pending: the reveal shows instantly, grading spins per problem", () => {
+		const s = set({
+			problems: [readyProblem("pp_1", ["n3"], { answer: "because arguing is intentional action" })],
+		});
+		const live = renderToStaticMarkup(
+			<PracticeExamBody set={s} {...examBase} liveGradeIds={new Set(["pp_1"])} />,
+		);
+		// Instant reveal — the solution needs no grade.
+		assert.ok(live.includes('data-testid="solution-pp_1"'));
+		assert.ok(live.includes('data-testid="rubric-pp_1"'));
+		// The live spinner for exactly this problem.
+		assert.ok(live.includes('data-testid="grading-pp_1"'));
+		assert.ok(live.includes("Grading"));
+		assert.ok(!live.includes('data-testid="grade-pp_1"'), "no score yet");
+		// No live row (dropped grade): honest, no eternal spinner.
+		const dropped = renderToStaticMarkup(<PracticeExamBody set={s} {...examBase} />);
+		assert.ok(dropped.includes('data-testid="grade-interrupted-pp_1"'));
+		assert.ok(!dropped.includes('data-testid="grading-pp_1"'));
 	});
 
 	it("a failed problem says so; a failed set says so", () => {