practice round: dead session starts, prompt laws, preamble, label unify

THE START BUG (owner report, reproduced live both kinds): new sessions
(?prompt flow — practice and teach alike) sat dead until a second
message, which then persisted WITHOUT the first. Root cause, proven
both directions: the submit POST rode the view's consumeAbort
controller; React StrictMode's simulated remount fires Diet A's
unmount cleanup (model.stop()) ~8ms in and killed the POST mid-flight;
the page's sentInitial guard had already flipped, so it never retried.
Teach was equally broken — only unnoticed, because every teach chat in
use predates the diet and practice starts are always fresh. Fix: the
submit law — POSTs are not abortable by view teardown (they are ~100ms
acks since Diet B and cannot starve the pool); after the ack, a
consumeAbort identity check guards the stream attach. Pinned with the
stop-mid-submit regression test. Live: StrictMode on, practice draft
POST 200/67ms, stream attached, message persisted, problem posed.

PRACTICE PROMPT (00-base): the opening rule — material arrives two
ways, both first-class (picked propositions primary; free-form —
topics, course material, files/PDFs — fully supported, never refused);
as soon as material exists the reply poses, at most one short line
before the problem call, no warm-up interview. Plus the hard law: no
problem is ever conversation — every problem through the tool (no
thinking field/no reveal/no verdict attaches to prose).

GRAPH-CONTEXT PREAMBLE: custom markers flatten to user-role on the
wire, so the old "Contextualization — the learner picked…" read like a
system broadcast in the learner's voice channel. Now the bracket
convention: "[Session context] — picked from the learner's knowledge
map…".

SIDEBAR: busy rows unify to "Working…" for both kinds (the spinner's
default label included); "Practicing…"/"Teacher is working…" retired.

Gates: 1490/1490, typecheck, lint. doctrine's stale doc pointer fixed.

components/braille-spinner.tsx

@@ -36,7 +36,7 @@ export const SPINNER_FRAMES = FRAMES.length;
 
 export function BrailleSpinner({
 	className,
-	label = "Teacher is working",
+	label = "Working",
 }: {
 	/** Sizing/position classes; height drives the scale (width is the cell's 1:2 aspect). */
 	className?: string;

components/session-core.ts

@@ -561,8 +561,19 @@ export class SessionModel {
 			this.tail = [...this.tail, ...optimistic];
 		});
 		try {
-			const res = await this.postInputEvent(input, controller.signal);
-			if (controller.signal.aborted) return;
+			// SUBMITS ARE NOT ABORTABLE BY VIEW TEARDOWN (owner, 2026-10-10 —
+			// the dead-session-start postmortem): the POST must NOT ride
+			// consumeAbort. Diet A's abort-on-unmount (session.ts's stop())
+			// fires on React StrictMode's simulated remount in dev — it killed
+			// the ?prompt first send ~8ms in (POST aborted, never retried:
+			// the page's sentInitial guard had already flipped), leaving the
+			// session dead until a second message, which then persisted
+			// WITHOUT the first — the optimistic tail rode a record that never
+			// contained it. The POST is a ~100ms ack since Diet B; it cannot
+			// starve the connection pool, so it needs no teardown guard. The
+			// STREAM consume stays on the controller — releasing that held
+			// connection is Diet A's whole job.
+			const res = await this.postInputEvent(input);
 			if (res.status === 409) {
 				this.setError("A turn is already running — try again in a moment.");
 				this.setStatus("error");
@@ -582,6 +593,10 @@ export class SessionModel {
 			// replay lands on top). One live view connection per page, always —
 			// the browser's 6-per-origin pool is the scarce resource.
 			await res.text().catch(() => {}); // drain the tiny ack; release the socket
+			// A stop() or a newer send/consume won while the ack was in
+			// flight: the turn is live server-side either way — do not attach
+			// a stream from a view that is gone or superseded.
+			if (this.consumeAbort !== controller) return;
 			await this.resumeStream(true);
 		} catch (err) {
 			if ((err as Error).name === "AbortError") return; // stop() or a newer consume won

components/sidebar.tsx

@@ -248,7 +248,7 @@ function sessionMeta(chat: ChatListItem): string {
 	if ((chat.kind ?? "teach") === "practice" && chat.pendingProblem) {
 		return `Problem waiting · ${timeAgo(chat.updatedAt)}`;
 	}
-	if (chat.busy) return (chat.kind ?? "teach") === "practice" ? "Practicing…" : "Teacher is working…";
+	if (chat.busy) return "Working…";
 	return timeAgo(chat.updatedAt);
 }
 

src/agent/prompts/practice/00-base.md

@@ -2,9 +2,18 @@
 
 You are the agent of a learning harness, running practice sessions. Your job is to make held knowledge come to mind and run — the doctrine section carries the method; this base carries the register, the accuracy contract, and the tool mechanics.
 
+## The opening — straight to problems (owner, 2026-10-10)
+
+Material arrives two ways, and both are first-class starts:
+
+- **Picked propositions** — the session context carries them at the top of the transcript (ids ready for the `problem` tool's target field). This is the primary path: the first reply poses from them directly.
+- **Free-form** — a topic in the learner's own words, course material, files or PDFs they reference. Read what they point at (the side tools below); a topic description is already material enough to pose against. Never balk at a free-form start — never refuse it, never ask the learner to restate it in some other form, never treat picked propositions as the only legitimate entry.
+
+Either way, the law is the same: **as soon as the material for a problem exists, the reply poses.** At most one short line of orientation before the `problem` call — never a warm-up exchange, never clarifying questions when the material already bounds the demand. Calibration comes from the opening demands themselves (the doctrine's open-warm arc), not from an interview.
+
 ## Tool mechanics
 
-Two tools, and everything else is conversation. The mechanics only — the method (when to pose, what to pose, how to respond) is the doctrine's.
+Two tools, and everything else is conversation — with one hard exception: **no problem is ever conversation.** Every problem, first to last, is posed through the `problem` tool. A problem written as chat prose is a protocol violation — no thinking field can attach to it, no hidden model solution, no verdict, no retest. If you catch yourself writing a problem in a message, stop and make the call instead. The mechanics only — the method (when to pose, what to pose, how to respond) is the doctrine's.
 
 **`problem`** — poses one problem. The statement field is what the learner sees (markdown and LaTeX render — every piece of math in the statement and the model solution goes in LaTeX); the modelSolution is your private commitment, hidden from the learner until you conclude — solve and shortcut-hunt the problem yourself BEFORE posing: the committed solution is your own worked solution, never a hope. When the session's material lives in the map, target takes the proposition ids from the session context — ids are how every problem is traced to the propositions it exercises. When it does not (a topic with nothing in the map), omit target entirely: problems stand on their own, untagged. The call ends the turn. The learner then works in a thinking field; each submission arrives back as a *Your thinking* message. Whether it claims an answer is IN THE TEXT, not declared anywhere — read it:
 

src/agent/prompts/practice/10-doctrine.md

@@ -2,7 +2,7 @@
      §I material-arrival generalized (verbal descriptions, outside problems);
      §VIII pause law (owner round 16, 2026-10-06: concluding ends the turn;
      the learner's explicit go-ahead paces the stream). Tool mechanics live
-     in 00-base.md; theory in docs/vision-practice-sessions.md's source note. -->
+     in 00-base.md; theory in the archived vision-practice note (docs-archive). -->
 
 # The practice session
 

src/core/native-messages.ts

@@ -213,7 +213,12 @@ export function newGraphContextMessage(picks: readonly GraphContextPick[], chain
 	// ids at the seam). Chains below stay NAMES — they are comprehension
 	// context, not tags; names read, ids reference.
 	const lines = [
-		"Contextualization — the learner picked these propositions from their knowledge map when starting this session:",
+		// PREAMBLE LAW (owner, 2026-10-10): custom markers flatten to
+		// USER-role messages on the wire (toLlmMessages) — this text arrives
+		// in the learner's voice channel, so it must not read like a system
+		// broadcast. The bracket convention (NEXT_PROBLEM_TEXT's kin) marks
+		// it honestly as injected session context, not learner speech.
+		"[Session context] — picked from the learner's knowledge map when starting this session:",
 		"",
 		"Propositions (id — name: statement; the problem tool's target field uses these ids):",
 		...picks.map((p) => `- [${p.id}] ${p.name}: ${p.statement}`),

tests/graph-context.test.ts

@@ -48,7 +48,7 @@ describe("newGraphContextMessage", () => {
 	it("frames the context for the model: propositions listed, chains appended", () => {
 		const m = newGraphContextMessage(PICKS, ["Modus ponens → Soundness"]);
 		assert.equal(m.customType, "graph-context");
-		assert.match(m.content, /Contextualization — the learner picked these propositions/);
+		assert.match(m.content, /\[Session context\] — picked from the learner's knowledge map/);
 		// IDS FIRST (owner round 9): every pick carries its id — the problem
 		// tool's target field references these; names alone no longer.
 		assert.ok(m.content.includes(`- [${PICKS[0]!.id}] Modus ponens: If P implies Q and P holds, Q holds.`));
@@ -69,7 +69,7 @@ describe("newGraphContextMessage", () => {
 		const wire = toLlmMessages([m as unknown as LhMessage] as never);
 		assert.equal(wire.length, 1);
 		assert.equal(wire[0]!.role, "user");
-		assert.ok(String((wire[0]!.content as { text?: string }[])[0]!.text).includes("Contextualization"));
+		assert.ok(String((wire[0]!.content as { text?: string }[])[0]!.text).includes("[Session context]"));
 	});
 
 	it("projectView: a user-side data part — never a text bubble", () => {

tests/render-sidebar.test.tsx

@@ -67,7 +67,7 @@ describe("SessionRow", () => {
 		assert.ok(html.includes("braille-frame"), "CSS-animated frames");
 		assert.ok((html.match(/class="braille-frame"/g) ?? []).length === 10, "all ten frames");
 		assert.ok(html.includes('data-frame="0"'), "frame 0 leads (static fallback)");
-		assert.ok(html.includes("Teacher is working"), "accessible label");
+		assert.ok(html.includes("Working"), "accessible label");
 		assert.ok(!html.includes("bg-attention"), "no colored state fill — monochrome by design");
 	});
 
@@ -77,7 +77,7 @@ describe("SessionRow", () => {
 		// contract can't silently re-widen: an extraction-only "working"
 		// row would be a double signal.
 		const html = render(item({ busy: true, pendingQuestion: false }));
-		assert.ok(html.includes("Teacher is working"), "the spinner's label names the turn, not agents");
+		assert.ok(html.includes("Working"), "the spinner's label names the turn, not agents");
 	});
 
 	it("the meta line: state replaces the count when the state is the useful fact", () => {
@@ -87,7 +87,7 @@ describe("SessionRow", () => {
 		assert.ok(!awaiting.includes("braille-spinner"), "…and the spinner stays off");
 
 		const working = render(item({ busy: true }));
-		assert.ok(working.includes("Teacher is working…"), "working meta");
+		assert.ok(working.includes("Working…"), "working meta");
 
 		// Owner, typography round 5: the message count is dropped — it
 		// informed no decision. Idle meta is just how long ago.
@@ -121,9 +121,10 @@ describe("timeAgo", () => {
 });
 
 describe("SessionRow practice badge (practice sessions, 2026-10-04)", () => {
-	it("a practice row carries the dumbbell badge and the Practicing meta while busy", () => {
+	it("a practice row carries the dumbbell badge and the unified Working meta while busy (owner, 2026-10-10)", () => {
 		const html = render(item({ kind: "practice", busy: true }));
-		assert.match(html, /Practicing…/);
+		assert.match(html, /Working…/);
+		assert.doesNotMatch(html, /Practicing…/);
 		assert.match(html, /aria-label="Practice session"/);
 	});
 
@@ -133,9 +134,9 @@ describe("SessionRow practice badge (practice sessions, 2026-10-04)", () => {
 		assert.doesNotMatch(html, /Practicing…/);
 	});
 
-	it("busy teaching rows still say the teacher is working", () => {
+	it("busy teaching rows say the same unified Working", () => {
 		const html = render(item({ busy: true }));
-		assert.match(html, /Teacher is working…/);
+		assert.match(html, /Working…/);
 	});
 
 	it("a practice row with a posed problem says the problem is waiting", () => {

tests/session-core.test.ts

@@ -593,6 +593,48 @@ describe("resumeStream (the reattach path)", () => {
 		assert.equal(m.getState().status, "ready");
 	});
 
+	it("SESSION START SURVIVES A STOP() RACING THE SUBMIT (owner, 2026-10-10 — the dead-practice-start postmortem)", async () => {
+		// React StrictMode's simulated remount fires the unmount cleanup
+		// (~8ms in) while the ?prompt first send's POST is in flight — the
+		// exact live repro: pre-fix, the POST rode consumeAbort and died
+		// with AbortError, the page's sentInitial guard never retried, and
+		// the session sat dead until a second message (which then persisted
+		// WITHOUT the first). The law: submits are not abortable by view
+		// teardown — the POST completes, the turn is server-side, and the
+		// dead view attaches no stream.
+		let resolvePost!: () => void;
+		let postAborted = false;
+		const fetches: string[] = [];
+		globalThis.fetch = (async (input: RequestInfo | URL, init?: RequestInit) => {
+			const url = String(input);
+			fetches.push(url);
+			if (url === "/api/chat") {
+				init?.signal?.addEventListener("abort", () => {
+					 postAborted = true;
+				});
+				await new Promise<void>((r) => {
+					 resolvePost = () => r();
+				});
+				return Response.json({ ok: true });
+			}
+			if (url === "/api/chats/chat_x") {
+				return Response.json({ messages: [{ id: "u1", role: "user", content: "quiz me", timestamp: 1 }] });
+			}
+			if (url === "/api/chats/chat_x/stream") return new Response("data: [DONE]\n\n", { status: 200 });
+			throw new Error(`unexpected fetch: ${url}`);
+		}) as typeof globalThis.fetch;
+		const m = model();
+		const sending = m.send({ type: "text", text: "quiz me" });
+		await new Promise((r) => setTimeout(r, 5)); // the POST is in flight
+		m.stop(); // StrictMode's simulated unmount lands mid-submit
+		resolvePost(); // the ack completes anyway
+		await sending;
+		assert.equal(postAborted, false, "the submit POST carries no teardown signal at all");
+		assert.ok(fetches.includes("/api/chat"), "the submit reached the server");
+		assert.ok(!fetches.some((u) => u.endsWith("/stream")), "a dead view attaches no stream — the turn is server-side");
+		assert.equal(m.getState().status, "ready");
+	});
+
 	it("REATTACH REPLAYS ONTO A CLEAN SLATE (owner, optimistic round 3): an aborted attempt's partials never double", async () => {
 		// StrictMode's simulated remount aborts the first resume mid-replay;
 		// its partial tail survived into the retry and the replay DOUBLED