practice UI: the dock, the transcript cards, layered-Esc discard

- PracticeDock (components/practice-dock.tsx): the active problem
  replaces the composer — statement (markdown+LaTeX) above, the 'Your
  thinking' composer-twin below with the two submit lanes (Nudge =
  thinking without a commit; Commit = answer commit; ⌘/Ctrl+Enter
  commits). Dictation claims the thinking field.
- Transcript cards (practice-cards.tsx + the artifact registry): the
  problem card (compact-expandable statement — the commitment NEVER
  renders), the conclude card (outcome + verdict + reveal; the
  dismissal synthesis is one muted line), and the user-side thinking
  register cards (Your thinking / Your solution).
- view.ts: the problem pose joins the placeholder fork (the ack never
  flips the part); practice-thinking markers project as data parts;
  problem-dismissed markers project nothing.
- chat.tsx: activeProblemOf drives the dock branch (question > problem
  > composer), the esc layering gains the problem rung (below question,
  above turn) with its discard confirm + the silent marker route; the
  thinking submissions POST through the session's optimistic appends.

components/abort-turn-dialog.tsx

@@ -24,7 +24,7 @@ import { createPortal } from "react-dom";
  */
 
 /** What Esc is aborting — drives copy and the confirm action. */
-export type AbortMode = "turn" | "question";
+export type AbortMode = "turn" | "question" | "problem";
 
 const COPY: Record<AbortMode, { title: string; line: string; action: string }> = {
 	turn: {
@@ -37,6 +37,11 @@ const COPY: Record<AbortMode, { title: string; line: string; action: string }> =
 		line: "Skipped — the teacher moves on without it.",
 		action: "Dismiss",
 	},
+	problem: {
+		title: "Discard this problem?",
+		line: "The problem is dropped — no solution is revealed.",
+		action: "Discard",
+	},
 };
 
 /** The dialog's pure body — exported for SSR pins (the delete-node

components/artifacts/index.ts

@@ -5,6 +5,7 @@ import { JobCard, PdfJobCard } from "@/components/artifacts/job-card";
 import { VisualCard } from "@/components/artifacts/visual-card";
 import { ProbeDoneCard } from "@/components/artifacts/probe-done-card";
 import { ToolCallCard } from "@/components/artifacts/tool-call-card";
+import { ProblemCard, ConcludeCard } from "@/components/practice-cards";
 
 /**
  * Artifact renderer registry — the extension point for tool-part UI.
@@ -37,6 +38,11 @@ export const artifactRenderers: Record<string, ComponentType<ArtifactPartProps>>
 	ls: ToolCallCard,
 	find: ToolCallCard,
 	grep: ToolCallCard,
+	// The practice pair (2026-10-04): the pose renders the statement ONLY
+	// (the commitment lives in the call's arguments and never renders);
+	// the conclusion carries the outcome + verdict + the reveal.
+	problem: ProblemCard,
+	conclude: ConcludeCard,
 	// The prober's graph tools (wave 7): same quiet expandable card —
 	// collapsed one-liner (tool name + the session id for
 	// list_propositions), the tool's own compact row-per-line output

components/chat.tsx

@@ -36,12 +36,22 @@ import { AbortTurnDialog, type AbortMode } from "@/components/abort-turn-dialog"
 import { WaypointsIcon } from "lucide-react";
 import type { PlanBlockData } from "@/src/core";
 import { QuestionDock } from "@/components/question-dock";
+import { PracticeDock } from "@/components/practice-dock";
+import { ThinkingCard, type PracticeThinkingData } from "@/components/practice-cards";
 import { TopBar } from "@/components/top-bar";
 import type { ArtifactPartProps, JobRecord, Phase3, QuestionAnswerData, TurnUsage } from "@/src/core";
 import type { LhViewMessage } from "@/src/core";
 import { PhaseChip, PhaseDivider } from "@/components/phase-divider";
 import { CoverageRing } from "@/components/extraction-coverage";
-import { dismissedAnswer, findPendingToolCall, phaseAt3, phaseTimeline, toolQuestionKind, quizNeedsReveal } from "@/src/core";
+import {
+	activeProblemOf,
+	dismissedAnswer,
+	findPendingToolCall,
+	phaseAt3,
+	phaseTimeline,
+	toolQuestionKind,
+	quizNeedsReveal,
+} from "@/src/core";
 import { ReadingThinkingField } from "@/components/reading-thinking";
 import { slotsConfigured, type ModelsSettings } from "@/src/core";
 import { useSettingsSaved } from "@/components/settings-signal";
@@ -190,7 +200,7 @@ export function Chat({
 	// (core/view.ts projectView); sends are ONE explicit input event each
 	// ({chatId, input} — the stash indirection died with the SDK), and the
 	// turn stream is the VERBATIM AgentEvent passthrough the server emits.
-	const { messages, nativeMessages, send, steer, steerQueue, submitAnswer, dismissQuestion, setMessages, adoptRecord, status, error, stop, clearError, resumeStream, setReattachSettled } =
+	const { messages, nativeMessages, send, steer, steerQueue, submitAnswer, dismissQuestion, dismissProblem, setMessages, adoptRecord, status, error, stop, clearError, resumeStream, setReattachSettled } =
 		useChatSession({ chatId, initialMessages, initiallyInFlight });
 
 	// The reattach settled terminal → the sync-and-continue seam (below).
@@ -321,9 +331,11 @@ export function Chat({
 				planOpen: planOpenRef.current,
 				setupOpen: setupOpenRef.current,
 				pending: pendingRef.current !== null,
+				problem: activeProblemRef.current !== null,
 				busy: busyRef.current,
 			});
 			if (target === "question") setAbortAsk("question");
+			else if (target === "problem") setAbortAsk("problem");
 			else if (target === "turn") setAbortAsk("turn");
 			else if (target === "mermaid") setMermaidFocus(null);
 			else if (target === "plan") setPlanOpen(false);
@@ -344,14 +356,21 @@ export function Chat({
 			// SILENT route — no turn, no wake, nothing generates. The session
 			// pauses at the user's choice; the next plain send is the wake.
 			const p = pendingRef.current;
-			if (!p) return;
-			const question = (p.input as { question?: string } | null)?.question ?? "";
-			const reading = readingThinkingRef.current.trim() || undefined;
-			clearReadingThinking();
-			const answer = dismissedAnswer(toolQuestionKind(p.tool), question);
-			void dismissQuestion(p.toolCallId, reading ? { ...answer, readingThinking: reading } : answer);
+			if (p) {
+				const question = (p.input as { question?: string } | null)?.question ?? "";
+				const reading = readingThinkingRef.current.trim() || undefined;
+				clearReadingThinking();
+				const answer = dismissedAnswer(toolQuestionKind(p.tool), question);
+				void dismissQuestion(p.toolCallId, reading ? { ...answer, readingThinking: reading } : answer);
+				return;
+			}
+			// The practice discard (owner, 2026-10-04): ask-style — the
+			// silent marker route; the conclude synthesis rides the user's
+			// next input. The composer returns immediately.
+			const problem = activeProblemRef.current;
+			if (problem) void dismissProblem(problem.toolCallId);
 		},
-		[abortInFlightTurn, dismissQuestion],
+		[abortInFlightTurn, dismissQuestion, dismissProblem],
 	);
 	// Mount continuation: if the stored transcript ends with a fulfilled tool
 	// (a job result landed while no client was open), resume the lesson — the
@@ -375,6 +394,15 @@ export function Chat({
 	// listener is mount-scoped; the value it needs is render-scoped).
 	const pendingRef = useRef(pending);
 	pendingRef.current = pending;
+
+	// THE ACTIVE PRACTICE PROBLEM (practice sessions, 2026-10-04): the
+	// same dock-ownership rule as a pending question — an active problem
+	// replaces the composer. Computed from the NATIVE record (the fold is
+	// the gate the tools themselves read), not the projected view.
+	const activeProblem = activeProblemOf(nativeMessages);
+	const activeProblemRef = useRef(activeProblem);
+	activeProblemRef.current = activeProblem;
+
 	const localStream = status === "submitted" || status === "streaming";
 	const busy = localStream || turnInFlight;
 	const busyRef = useRef(busy);
@@ -403,6 +431,20 @@ export function Chat({
 		void resumeStream();
 	}, [resumeStream]);
 
+	// The practice dock's two lanes (owner, 2026-10-04): both POST one
+	// thinking input against the ACTIVE problem — commit=false is the
+	// nudge (hint request), commit=true the answer commit. Each starts a
+	// turn; the dock stays mounted (the problem is still active until the
+	// agent concludes).
+	const submitThinking = useCallback(
+		(commit: boolean, text: string) => {
+			const problem = activeProblemRef.current;
+			if (!problem) return;
+			void send({ type: "thinking", problemCallId: problem.toolCallId, commit, text });
+		},
+		[send],
+	);
+
 	// Teach-phase check (W5, vision §2): a pending QUIZ that lands once a
 	// plan node is OCCUPIED (phaseAt3 "teach") starts collapsed behind a
 	// "Check your understanding" reveal button; probe- and plan-phase
@@ -553,7 +595,7 @@ export function Chat({
 	// a pending question still owns the interaction (the dock replaces the
 	// composer, and there is no live turn to steer anyway — questions end
 	// turns).
-	const canSend = (text.trim().length > 0 || dictation.active) && !pending;
+	const canSend = (text.trim().length > 0 || dictation.active) && !pending && !activeProblem;
 
 	const syncFromServer = useCallback(async () => {
 		const res = await fetch(`/api/chats/${chatId}`);
@@ -1194,6 +1236,13 @@ export function Chat({
 														);
 													case "step-start":
 														return pi > 0 ? <Separator key={pi} className="my-3" /> : null;
+													case "data-practice-thinking":
+														// The learner's practice submission (2026-10-04):
+														// user-side — the register (thinking trace /
+														// committed answer) is the card's title.
+														return (
+															<ThinkingCard key={pi} data={part.data as PracticeThinkingData} />
+														);
 													case "data-plan-block":
 														// The plan in the chat (wave 4): a frozen snapshot
 														// block — rendered as carried, never re-derived.
@@ -1285,6 +1334,8 @@ export function Chat({
 				    fold) and NEVER overlaps the composer. */}
 				<DockOverlay
 					pending={pending}
+					practice={activeProblem}
+					onSubmitThinking={submitThinking}
 					chatId={chatId}
 					plan={hasPlan ? <PlanMarginalia messages={messages} /> : undefined}
 					onOpenPlan={() => setPlanOpen(true)}
@@ -1426,13 +1477,19 @@ export function Chat({
  *  then the session overlays (mermaid paints above plan — later in DOM),
  *  then setup (self-closing — the gate only must not fire), then the
  *  2026-10-02 abort chain proper (question before turn). */
-export type EscAbortTarget = "mermaid" | "plan" | "setup" | "question" | "turn" | null;
+export type EscAbortTarget = "mermaid" | "plan" | "setup" | "question" | "problem" | "turn" | null;
 export function escAbortTarget(s: {
 	abortAsk: boolean;
 	mermaidFocus: boolean;
 	planOpen: boolean;
 	setupOpen: boolean;
 	pending: boolean;
+	/** An active practice problem (practice sessions, 2026-10-04): Esc
+	 *  opens the discard confirm — below a pending question (the two
+	 *  never coexist, but the layering stays strict), above the turn
+	 *  abort (a live turn can be running BEHIND an idle problem only in
+	 *  teaching sessions — practice problems end their pose turns). */
+	problem: boolean;
 	busy: boolean;
 }): EscAbortTarget {
 	if (s.abortAsk) return null; // the popup's own Esc — claimed by the dialog
@@ -1440,6 +1497,7 @@ export function escAbortTarget(s: {
 	if (s.planOpen) return "plan";
 	if (s.setupOpen) return "setup";
 	if (s.pending) return "question";
+	if (s.problem) return "problem";
 	if (s.busy) return "turn";
 	return null;
 }
@@ -1477,6 +1535,8 @@ export function shouldStampGeometryMute(nextH: number, prevH: number, pending: b
 
 function DockOverlay({
 	pending,
+	practice,
+	onSubmitThinking,
 	requiresReveal,
 	readingThinking,
 	onReadingThinking,
@@ -1494,6 +1554,12 @@ function DockOverlay({
 	queuedSteers,
 }: {
 	pending: ReturnType<typeof findPendingToolCall>;
+	/** The ACTIVE practice problem (practice sessions, 2026-10-04):
+	 *  {toolCallId, input} — dock ownership exactly like a pending
+	 *  question (the composer is replaced); null in teaching sessions. */
+	practice: { toolCallId: string; input: unknown } | null;
+	/** (commit, text) — the practice dock's two submit lanes. */
+	onSubmitThinking: (commit: boolean, text: string) => void;
 	/** Teach-phase pending question: arrives collapsed behind the reveal button (W5). */
 	requiresReveal: boolean;
 	/** The reading-thinking draft (owner 2026-10-03) — owned by ChatView so
@@ -1592,8 +1658,11 @@ function DockOverlay({
 	// again → re-open. The dead band keeps trackpad drift from chattering.
 	const expandedRef = useRef(expanded);
 	expandedRef.current = expanded;
-	const pendingRef = useRef(!!pending);
-	pendingRef.current = !!pending;
+	// Dock ownership (the fold machine, the reserve immunity, the arrival
+	// states): a pending question OR an active practice problem — either
+	// replaces the composer and owns the band.
+	const pendingRef = useRef(!!pending || !!practice);
+	pendingRef.current = !!pending || !!practice;
 	const requiresRevealRef = useRef(requiresReveal);
 	requiresRevealRef.current = requiresReveal;
 	const revealedRef = useRef(revealed);
@@ -1765,7 +1834,11 @@ function DockOverlay({
 		if (b) offer(b.getBoundingClientRect().height);
 	};
 
-	const mode = pending ? `question:${pending.toolCallId}` : "chat";
+	const mode = pending
+		? `question:${pending.toolCallId}`
+		: practice
+			? `practice:${practice.toolCallId}`
+			: "chat";
 	// The opening variant of a session appears instantly — the fade/rise is
 	// reserved for mid-session transitions.
 	const initialModeRef = useRef(mode);
@@ -1843,6 +1916,18 @@ function DockOverlay({
 									onEscape={dictationCancel}
 									dictationClaim={!revealPending}
 								/>
+							) : practice ? (
+								<PracticeDock
+									problemCallId={practice.toolCallId}
+									input={practice.input as { statement: string }}
+									expanded={expanded}
+									onExpand={() => {
+										setExpanded(true);
+										void suppressFoldDuringReveal();
+									}}
+									onSubmit={onSubmitThinking}
+									onEscape={dictationCancel}
+								/>
 							) : (
 								composer
 							)}

components/practice-cards.tsx

@@ -0,0 +1,138 @@
+"use client";
+
+import { useState } from "react";
+import { ChevronRightIcon } from "lucide-react";
+import { MessageResponse } from "@/components/ai-elements/message";
+import type { ArtifactPartProps } from "@/src/core";
+import { cn } from "@/lib/utils";
+
+/**
+ * The practice transcript cards (practice sessions, owner design
+ * 2026-10-04): three quiet records in the stream —
+ *
+ * - ProblemCard — a posed problem: the statement, compact-expandable
+ *   (like every card here; the dock is the working surface, this is the
+ *   record). The commitment NEVER renders — only the call's statement.
+ * - ConcludeCard — the conclusion: outcome badge + verdict + the reveal
+ *   (the committed solution, shown when the problem ended). A dismissal
+ *   synthesis (outcome:"dismissed") renders as one muted line.
+ * - ThinkingCard — the learner's own submission, user-side: the register
+ *   is the two buttons' (Nudge = working trace, Commit = answer).
+ */
+
+/** The practice-thinking marker's details (native-messages.ts). */
+export interface PracticeThinkingData {
+	problemCallId: string;
+	commit: boolean;
+	text: string;
+}
+
+export function ProblemCard({ part }: ArtifactPartProps) {
+	const [open, setOpen] = useState(false);
+	const input = (part.input ?? {}) as { statement?: string };
+	const statement = typeof input.statement === "string" ? input.statement : "";
+	return (
+		<div data-testid="problem-card" className="my-1">
+		<button
+			type="button"
+			onClick={() => setOpen((v) => !v)}
+			className="flex w-full cursor-pointer items-center gap-2 rounded-lg border border-border/60 bg-card/60 px-3 py-2 text-left text-sm text-muted-foreground transition-colors hover:text-foreground"
+		>
+			<ChevronRightIcon className={cn("size-4 shrink-0 transition-transform", open && "rotate-90")} />
+			<span className="font-medium">Problem</span>
+			<span className="min-w-0 flex-1 truncate">{statement}</span>
+		</button>
+		{open && (
+			<div className="lh-prose mt-1 rounded-lg border border-border/60 bg-card/60 px-4 py-3 text-[15px]">
+				<MessageResponse>{statement}</MessageResponse>
+			</div>
+		)}
+		</div>
+	);
+}
+
+const OUTCOME_LABEL: Record<string, string> = {
+	solved: "Solved",
+	solvedWithHints: "Solved with hints",
+	movedOn: "Moved on",
+	surrendered: "Surrendered",
+	dismissed: "Dismissed",
+};
+
+export function ConcludeCard({ part }: ArtifactPartProps) {
+	const [open, setOpen] = useState(false);
+	const input = (part.input ?? {}) as {
+		outcome?: string;
+		verdict?: string;
+		solutionReveal?: string;
+	};
+	const outcome = typeof input.outcome === "string" ? input.outcome : "";
+	const verdict = typeof input.verdict === "string" ? input.verdict : "";
+	const reveal = typeof input.solutionReveal === "string" ? input.solutionReveal : "";
+
+	// The dismissal synthesis: no verdict, no reveal — one muted line (the
+	// learner clicked; the record needs only the fact).
+	if (outcome === "dismissed") {
+		return (
+			<div data-testid="conclude-card" className="my-1 px-1 text-sm text-muted-foreground/70">
+				Problem dismissed.
+			</div>
+		);
+	}
+
+	return (
+		<div data-testid="conclude-card" className="my-1">
+		<button
+			type="button"
+			onClick={() => setOpen((v) => !v)}
+			className="flex w-full cursor-pointer items-center gap-2 rounded-lg border border-border/60 bg-card/60 px-3 py-2 text-left text-sm text-muted-foreground transition-colors hover:text-foreground"
+		>
+			<ChevronRightIcon className={cn("size-4 shrink-0 transition-transform", open && "rotate-90")} />
+			<span className="font-medium">{OUTCOME_LABEL[outcome] ?? "Concluded"}</span>
+			<span className="min-w-0 flex-1 truncate">{verdict}</span>
+		</button>
+		{open && (
+			<div className="mt-1 space-y-2 rounded-lg border border-border/60 bg-card/60 px-4 py-3 text-[15px]">
+				{verdict.length > 0 && (
+					<div className="text-sm text-foreground">
+						<MessageResponse>{verdict}</MessageResponse>
+					</div>
+				)}
+				{reveal.length > 0 && (
+					<div className="border-t border-border/50 pt-2">
+						<div className="mb-1 text-xs font-medium uppercase tracking-wide text-muted-foreground">
+							The solution
+						</div>
+						<div className="lh-prose">
+							<MessageResponse>{reveal}</MessageResponse>
+						</div>
+					</div>
+				)}
+			</div>
+		)}
+		</div>
+	);
+}
+
+export function ThinkingCard({ data }: { data: PracticeThinkingData }) {
+	const [open, setOpen] = useState(true);
+	return (
+		<div
+			data-testid="thinking-card"
+			data-commit={data.commit ? "true" : "false"}
+			className="ml-auto max-w-[85%] rounded-2xl border border-border/60 bg-muted/40 px-4 py-3"
+		>
+			<button
+				type="button"
+				onClick={() => setOpen((v) => !v)}
+				className="flex w-full cursor-pointer items-center gap-2 text-left text-xs font-medium uppercase tracking-wide text-muted-foreground"
+			>
+				{data.commit ? "Your solution" : "Your thinking"}
+				<ChevronRightIcon className={cn("size-3.5 shrink-0 transition-transform", open && "rotate-90")} />
+			</button>
+			{open && (
+				<div className="mt-1.5 whitespace-pre-wrap text-[15px]">{data.text}</div>
+			)}
+		</div>
+	);
+}

components/practice-dock.tsx

@@ -0,0 +1,164 @@
+"use client";
+
+import { useCallback, useRef, useState } from "react";
+import { ChevronRightIcon } from "lucide-react";
+import { MessageResponse } from "@/components/ai-elements/message";
+import { joinDictation, useDictationTarget } from "@/components/dictation";
+import { cn } from "@/lib/utils";
+
+/**
+ * The practice dock (practice sessions, owner design 2026-10-04): an
+ * ACTIVE problem replaces the chat composer — the persistent bottom blob
+ * morphs into the problem. The agent's statement above; the learner's
+ * half below — "Your thinking", a labeled composer-twin field (the
+ * question dock's discipline: Enter makes a newline, it is for dumping)
+ * with TWO submit buttons:
+ *
+ * - **Nudge** — submit the thinking WITHOUT a committed answer: working
+ *   trace, hint request (the ladder answers, one rung per request).
+ * - **Commit** — the thinking contains an arrived answer.
+ *
+ * ⌘/Ctrl+Enter commits (the universal submit chord). One problem may
+ * carry many submissions; each starts a turn.
+ *
+ * Collapse (scroll-up → slim bar) is owned by the DockOverlay; this
+ * component is content only, and the expanded form stays MOUNTED while
+ * collapsed (hidden) so a half-written trace survives scrolling.
+ *
+ * The commitment (modelSolution, decisionPoints, …) rides the tool call's
+ * arguments and is NOT rendered here — only the statement is the
+ * learner's. Esc dismisses the problem (the layered-Esc chain; the
+ * confirm dialog then the silent route) — claimed by the page, not here.
+ */
+
+export interface PracticeDockProps {
+	/** The active problem's tool-call id (submissions target it). */
+	problemCallId: string;
+	/** The pose's arguments — only the statement is the learner's (the
+	 *  mode badge would edge toward announcing the target; dropped). */
+	input: { statement: string };
+	/** Collapse state, owned by the DockOverlay. */
+	expanded: boolean;
+	onExpand: () => void;
+	/** (commit, text) — POST {type:"thinking"}; commit=false is the nudge. */
+	onSubmit: (commit: boolean, text: string) => void;
+	/** Escape in the thinking field stops dictation (threaded from the page). */
+	onEscape?: () => void;
+}
+
+export function PracticeDock({ problemCallId, input, expanded, onExpand, onSubmit, onEscape }: PracticeDockProps) {
+	const [thinking, setThinking] = useState("");
+	// Ref MIRRORS the field ("nothing gets lost", the question-dock
+	// discipline): a submit resuming after `await finishDictation()` reads
+	// the tail, never a stale closure.
+	const thinkingRef = useRef("");
+
+	useDictationTarget(
+		useCallback(
+			(t: string) => {
+				const v = joinDictation(thinkingRef.current, t);
+				thinkingRef.current = v;
+				setThinking(v);
+			},
+			[],
+		),
+		true,
+	);
+
+	const submit = (commit: boolean) => {
+		const text = thinkingRef.current.trim();
+		if (text.length === 0) return;
+		thinkingRef.current = "";
+		setThinking("");
+		onSubmit(commit, text);
+	};
+
+	/* ── the collapsed bar ── */
+	if (!expanded) {
+		return (
+			<button
+				type="button"
+				data-testid="practice-dock-bar"
+				onClick={onExpand}
+				className="flex w-full cursor-pointer items-center gap-2 px-4 py-3 text-left text-sm text-muted-foreground transition-colors hover:text-foreground"
+			>
+				<ChevronRightIcon className="size-4 shrink-0 rotate-90" />
+				<span className="font-medium">Problem</span>
+				<span className="min-w-0 flex-1 truncate">{input.statement}</span>
+			</button>
+		);
+	}
+
+	/* ── the expanded form ── */
+	return (
+		<div data-testid="practice-dock" data-problem={problemCallId}>
+			{/* The agent's half: the statement, markdown + LaTeX rendered. */}
+			<div className="max-h-[40vh] overflow-y-auto px-4 pt-3 pb-2">
+				<div className="lh-prose text-[15px]">
+					<MessageResponse>{input.statement}</MessageResponse>
+				</div>
+			</div>
+
+			{/* The learner's half — a composer TWIN (the question dock's
+			    discipline): Enter makes a newline; the buttons submit. */}
+			<div
+				data-testid="practice-thinking-field"
+				className="m-1.5 rounded-xl border border-border/70 bg-background/60 transition-colors focus-within:border-primary/50"
+			>
+				<div className="px-2.5 pt-2 text-xs font-medium uppercase tracking-wide text-muted-foreground">
+					Your thinking
+				</div>
+				<textarea
+					value={thinking}
+					onChange={(e) => {
+						thinkingRef.current = e.target.value;
+						setThinking(e.target.value);
+					}}
+					onKeyDown={(e) => {
+						// Esc ends dictation — stopPropagation claims it (the
+						// keyboard machine) so the window chain doesn't also fire.
+						if (e.key === "Escape" && onEscape) {
+							e.preventDefault();
+							e.stopPropagation();
+							onEscape();
+							return;
+						}
+						// ⌘↵ on macOS, Ctrl↵ elsewhere — the universal submit
+						// chord; here it COMMITS (the stronger of the two acts).
+						if (e.key === "Enter" && (e.metaKey || e.ctrlKey)) {
+							e.preventDefault();
+							submit(true);
+						}
+					}}
+					placeholder="Work here — say as much of your thinking as you have. Nudge asks for a hint without committing; Commit submits an answer."
+					rows={4}
+					className={cn(
+						"field-sizing-content lh-input max-h-64 min-h-16 w-full resize-none bg-transparent px-2.5 pb-2 outline-none placeholder:text-muted-foreground",
+					)}
+				/>
+				{/* The two submit lanes — docked inside the field like the
+				    composer's send, right-aligned. */}
+				<div className="flex items-center justify-end gap-1.5 px-1.5 pb-1.5">
+					<button
+						type="button"
+						data-testid="practice-nudge"
+						disabled={thinking.trim().length === 0}
+						onClick={() => submit(false)}
+						className="rounded-lg border border-border/70 px-3 py-1.5 text-sm text-muted-foreground transition-colors hover:text-foreground disabled:pointer-events-none disabled:opacity-40"
+					>
+						Nudge
+					</button>
+					<button
+						type="button"
+						data-testid="practice-commit"
+						disabled={thinking.trim().length === 0}
+						onClick={() => submit(true)}
+						className="rounded-lg bg-primary px-3 py-1.5 text-sm font-medium text-primary-foreground transition-colors hover:bg-primary/90 disabled:pointer-events-none disabled:opacity-40"
+					>
+						Commit
+					</button>
+				</div>
+			</div>
+		</div>
+	);
+}

components/session-core.ts

@@ -18,6 +18,8 @@ import type { ToolResultMessage } from "@earendil-works/pi-ai";
 import {
 	needsContinuation,
 	newAnswerResult,
+	newProblemDismissedMarker,
+	newThinkingMessage,
 	newUserMessage,
 	projectView,
 	type ChatInput,
@@ -503,7 +505,12 @@ export class SessionModel {
 		// adoption can tell them from the record's absorbed copies.
 		const optimistic: LhMessage[] = [];
 		if (input.type === "text") optimistic.push({ ...newUserMessage(input.text), id: localId() });
-		else if (input.type === "answer") {
+		else if (input.type === "thinking") {
+			// The practice submissions (2026-10-04): the marker lands
+			// optimistically — the register (trace / commit) renders from
+			// its details the moment the button fires.
+			optimistic.push({ ...newThinkingMessage(input.problemCallId, input.commit, input.text), id: localId() });
+		} else if (input.type === "answer") {
 			const tool = pendingCallTool([...this.base, ...this.tail], input.toolCallId) ?? "quiz";
 			optimistic.push({ ...newAnswerResult(input.toolCallId, tool, input.answer), id: localId() });
 		}
@@ -605,6 +612,27 @@ export class SessionModel {
 		}
 	}
 
+	/** The problem discard (practice sessions, owner 2026-10-04): the
+	 *  ask-style dismissal — the UI-only marker lands optimistically, then
+	 *  the SILENT route persists it (no turn, no wake). The composer
+	 *  returns; the conclude synthesis rides the user's next input. */
+	async dismissProblem(problemCallId: string): Promise<void> {
+		if (!this.readyRef) return;
+		this.mutate(() => {
+			this.tail = [...this.tail, { ...newProblemDismissedMarker(problemCallId), id: localId() }];
+		});
+		try {
+			const res = await this.fetch(`/api/chats/${this.chatId}/dismiss`, {
+				method: "POST",
+				headers: { "Content-Type": "application/json" },
+				body: JSON.stringify({ input: { type: "dismiss-problem", problemCallId } }),
+			});
+			if (!res.ok) throw new Error(`The dismissal failed (${res.status}).`);
+		} catch (err) {
+			this.setError((err as Error).message);
+		}
+	}
+
 	/** Local detach: cancel the consume, keep the partial tail. The page's
 	 *  settle watch adopts the record when the server turn finishes. */
 	stop(): void {

components/session.ts

@@ -98,6 +98,10 @@ export function useChatSession({ chatId, initialMessages, initiallyInFlight }: U
 		(toolCallId: string, answer: QuestionAnswerData) => void model.dismissQuestion(toolCallId, answer),
 		[model],
 	);
+	const dismissProblem = useCallback(
+		(problemCallId: string) => void model.dismissProblem(problemCallId),
+		[model],
+	);
 	const setMessages = useCallback((record: LhMessage[]) => model.setMessages(record), [model]);
 	const adoptRecord = useCallback((record: LhMessage[]) => model.adoptRecord(record), [model]);
 	const stop = useCallback(() => model.stop(), [model]);
@@ -114,6 +118,7 @@ export function useChatSession({ chatId, initialMessages, initiallyInFlight }: U
 		steer,
 		submitAnswer,
 		dismissQuestion,
+		dismissProblem,
 		setMessages,
 		adoptRecord,
 		stop,

src/core/view.ts

@@ -220,6 +220,18 @@ export function projectView(messages: readonly LhMessage[], live?: LiveTurnState
 	return out;
 }
 
+/** The dock-owned tools: question tools (client-owned results — the dock
+ *  mounts on the dangling call) and the practice pose (its ack is FINAL —
+ *  details: null, never replaced — and the card + dock read the call's
+ *  input; the placeholder must never flip the part to output-available).
+ *  PRACTICE (2026-10-04): problem joins the placeholder fork; conclude is
+ *  a NORMAL tool part (its result acks with no payload, details null —
+ *  but the ConcludeCard reads the call's input, and output-available with
+ *  output undefined renders fine). */
+function isPlaceholderResultTool(name: string): boolean {
+	return (QUESTION_TOOLS as readonly string[]).includes(name) || name === "problem";
+}
+
 /** A tool call block → its view part, with the live execution layer. */
 function toolPartOf(
 	block: { id: string; name: string; arguments?: unknown },
@@ -231,7 +243,7 @@ function toolPartOf(
 		input: block.arguments,
 	};
 	const exec = live?.executions.get(block.id);
-	const isQuestion = (QUESTION_TOOLS as readonly string[]).includes(block.name);
+	const isQuestion = isPlaceholderResultTool(block.name);
 	if (exec) {
 		if (exec.isError) {
 			// An invalid call NEVER becomes input-available — the dock's mount
@@ -267,7 +279,7 @@ function applyResultTo(part: LhViewPart | undefined, result: ToolResultMessage):
 		// Flipping the part to output-available on the placeholder would hand
 		// AnsweredCard a null and crash the render (the live crash, 2026-09-26).
 		const tool = part.type.startsWith("tool-") ? part.type.slice("tool-".length) : part.type;
-		const isQuestion = (QUESTION_TOOLS as readonly string[]).includes(tool);
+		const isQuestion = isPlaceholderResultTool(tool);
 		if (isQuestion && !result.isError && result.details == null) return;
 		applyResult(part, result);
 	}
@@ -313,6 +325,22 @@ function projectMarker(marker: LhMarkerMessage, out: LhViewMessage[]): void {
 			});
 			return;
 		}
+		case "practice-thinking": {
+			// The learner's working trace / committed answer (practice
+			// sessions): a user-side card keyed on the structured details
+			// (problemCallId, commit, text) — the register lives in the card,
+			// not re-parsed from content.
+			out.push({
+				id: marker.id,
+				role: "user",
+				parts: [{ type: "data-practice-thinking", id: `pt_${marker.id}`, data: marker.details }],
+			});
+			return;
+		}
+		case "problem-dismissed":
+			// UI-only (the ask-style dismissal): the synthesized conclude
+			// pair — which rides the NEXT input — carries the record's face.
+			return;
 		case "plan-block": {
 			// No message of its own: splice into the preceding assistant
 			// group, IN FLOW after the last successful plan_init call.

tests/esc-layering.test.ts

@@ -12,7 +12,7 @@ import { escAbortTarget } from "../components/chat.tsx";
  * pure) is the defense. Priority = stacking order.
  */
 describe("escAbortTarget (the layered-Esc ruling)", () => {
-	const none = { abortAsk: false, mermaidFocus: false, planOpen: false, setupOpen: false, pending: false, busy: false };
+	const none = { abortAsk: false, mermaidFocus: false, planOpen: false, setupOpen: false, pending: false, problem: false, busy: false };
 
 	it("no overlays: the 2026-10-02 chain stands (question before turn)", () => {
 		assert.equal(escAbortTarget({ ...none, pending: true }), "question");
@@ -21,6 +21,12 @@ describe("escAbortTarget (the layered-Esc ruling)", () => {
 		assert.equal(escAbortTarget({ ...none, pending: true, busy: true }), "question", "a pending question outranks the turn");
 	});
 
+	it("an active practice problem sits between question and turn (2026-10-04)", () => {
+		assert.equal(escAbortTarget({ ...none, problem: true }), "problem");
+		assert.equal(escAbortTarget({ ...none, problem: true, busy: true }), "problem", "the problem card outranks the turn abort");
+		assert.equal(escAbortTarget({ ...none, planOpen: true, problem: true }), "plan", "an open popup still outranks the problem");
+	});
+
 	it("an open overlay claims Esc over a pending question — the owner's report", () => {
 		for (const overlay of ["mermaidFocus", "planOpen", "setupOpen"] as const) {
 			const target = escAbortTarget({ ...none, [overlay]: true, pending: true });

tests/render-practice-surface.test.tsx

@@ -0,0 +1,166 @@
+/**
+ * THE PRACTICE SURFACE — SSR render pins (the render-suite discipline:
+ * pure bodies, renderToStaticMarkup, testids). The dock (the active
+ * problem replaces the composer: statement above, "Your thinking"
+ * composer-twin below, the TWO submit lanes — Nudge without a commit,
+ * Commit with one; ⌘/Ctrl+Enter commits), the transcript cards (the
+ * problem's compact-expandable statement — commitment NEVER renders;
+ * the conclusion's outcome + verdict + reveal; the learner's thinking
+ * register cards), and the view projection (the thinking marker's
+ * data part; the dismissal's silence).
+ */
+
+import React from "react";
+(globalThis as Record<string, unknown>).React = React;
+
+import assert from "node:assert/strict";
+import { renderToStaticMarkup } from "react-dom/server";
+import { describe, it } from "node:test";
+
+import { PracticeDock } from "../components/practice-dock.tsx";
+import { ConcludeCard, ProblemCard, ThinkingCard } from "../components/practice-cards.tsx";
+import { projectView } from "../src/core/view.ts";
+import type { ArtifactPartProps } from "../src/core";
+import {
+	newThinkingMessage,
+	PRACTICE_PROBLEM_TOOL,
+	type LhMessage,
+} from "../src/core/native-messages.ts";
+
+const part = (over: Partial<ArtifactPartProps["part"]>): ArtifactPartProps["part"] => ({
+	type: "tool-problem",
+	state: "input-available",
+	toolCallId: "call_p1",
+	...over,
+});
+
+// ── the dock ─────────────────────────────────────────────────────────────────
+
+describe("PracticeDock", () => {
+	it("expanded: statement renders, the two lanes sit in the thinking field", () => {
+		const html = renderToStaticMarkup(
+			<PracticeDock
+				problemCallId="call_p1"
+				input={{ statement: "Show that the sum is even." }}
+				expanded={true}
+				onExpand={() => {}}
+				onSubmit={() => {}}
+			/>,
+		);
+		assert.match(html, /Show that the sum is even\./);
+		assert.match(html, /Your thinking/);
+		assert.match(html, /data-testid="practice-nudge"/);
+		assert.match(html, /data-testid="practice-commit"/);
+		// The buttons carry their lane in the disabled gate; both start
+		// disabled (empty field).
+		assert.match(html, /disabled/);
+	});
+
+	it("collapsed: the slim bar carries the statement excerpt", () => {
+		const html = renderToStaticMarkup(
+			<PracticeDock
+				problemCallId="call_p1"
+				input={{ statement: "Show that the sum is even." }}
+				expanded={false}
+				onExpand={() => {}}
+				onSubmit={() => {}}
+			/>,
+		);
+		assert.match(html, /data-testid="practice-dock-bar"/);
+		assert.match(html, /Show that the sum is even\./);
+	});
+});
+
+// ── the transcript cards ─────────────────────────────────────────────────────
+
+describe("the practice transcript cards", () => {
+	it("ProblemCard: the statement renders — the commitment NEVER does", () => {
+		const html = renderToStaticMarkup(
+			<ProblemCard
+				part={part({
+					input: {
+						statement: "Prove the parity claim.",
+						mode: "recall",
+						modelSolution: "Pair them.",
+						decisionPoints: ["pairing"],
+						expectedWrongMoves: [{ move: "induction", resolution: "pairing is direct" }],
+						strategy: "near-twin",
+						rationale: "weakest target",
+					},
+				})}
+			/>,
+		);
+		assert.match(html, /data-testid="problem-card"/);
+		assert.match(html, /Prove the parity claim\./);
+		for (const hidden of ["Pair them.", "induction", "near-twin", "weakest target", "pairing"]) {
+			assert.doesNotMatch(html, new RegExp(hidden.replace(/[.*+?^${}()|[\]\\]/g, "\\$&")), `commitment leaked: ${hidden}`);
+		}
+	});
+
+	it("ConcludeCard: outcome badge + verdict headline; the reveal expands", () => {
+		const html = renderToStaticMarkup(
+			<ConcludeCard
+				part={part({
+					type: "tool-conclude",
+					input: { outcome: "solvedWithHints", verdict: "The pairing came after R2.", solutionReveal: "Pair them; each pair is even." },
+				})}
+			/>,
+		);
+		assert.match(html, /data-testid="conclude-card"/);
+		assert.match(html, /Solved with hints/);
+		assert.match(html, /The pairing came after R2\./);
+	});
+
+	it("ConcludeCard: the dismissal synthesis is one muted line — no reveal card", () => {
+		const html = renderToStaticMarkup(
+			<ConcludeCard part={part({ type: "tool-conclude", input: { outcome: "dismissed" } })} />,
+		);
+		assert.match(html, /Problem dismissed\./);
+		assert.doesNotMatch(html, /The solution/);
+	});
+
+	it("ThinkingCard: the register is the title (trace vs solution)", () => {
+		const trace = renderToStaticMarkup(<ThinkingCard data={{ problemCallId: "c", commit: false, text: "stuck at step two" }} />);
+		assert.match(trace, /Your thinking/);
+		assert.doesNotMatch(trace, /Your solution/);
+		const commit = renderToStaticMarkup(<ThinkingCard data={{ problemCallId: "c", commit: true, text: "It is 42." }} />);
+		assert.match(commit, /Your solution/);
+	});
+});
+
+// ── the view projection ──────────────────────────────────────────────────────
+
+describe("the practice view projection", () => {
+	it("the thinking marker projects as a user-side data part (register in details)", () => {
+		const marker = newThinkingMessage("call_p1", true, "It is 42.");
+		const view = projectView([marker as LhMessage]);
+		assert.equal(view.length, 1);
+		assert.equal(view[0]!.role, "user");
+		const dataPart = view[0]!.parts[0]!;
+		assert.equal(dataPart.type, "data-practice-thinking");
+		assert.deepEqual(dataPart.data, { problemCallId: "call_p1", commit: true, text: "It is 42." });
+	});
+
+	it("the problem pose's ack keeps the part input-available (the dock's mount)", () => {
+		// Pose call + ack result (details: null — the placeholder fork).
+		const messages = [
+			{
+				id: "a1",
+				role: "assistant",
+				content: [{ type: "toolCall", id: "call_p1", name: PRACTICE_PROBLEM_TOOL, arguments: { statement: "S." } }],
+			},
+			{
+				id: "r1",
+				role: "toolResult",
+				toolCallId: "call_p1",
+				toolName: PRACTICE_PROBLEM_TOOL,
+				content: [{ type: "text", text: "Problem posed" }],
+				details: null,
+				isError: false,
+			},
+		] as unknown as LhMessage[];
+		const view = projectView(messages);
+		const toolPart = view[0]!.parts.find((p) => p.type === `tool-${PRACTICE_PROBLEM_TOOL}`)!;
+		assert.equal(toolPart.state, "input-available");
+	});
+});