ui: round 8 — fuzzy session search, stacked doors, All right, teach divider at the step seam

- SESSION SEARCH goes fuzzy on the SAME fuzzyScore the model pickers
  use (de0c286's util — one scoring across every search surface):
  ranked by score instead of raw substring; empty query keeps order.
- SIDEBAR: New Teaching / New Practice STACK (full-width rows); the
  kind filter reads Teaching · Practice · All — the real modes first,
  All as the escape hatch, mirroring the stack above. Home stays in the
  LH band (owner-confirmed).
- TEACH DIVIDER, the stacked-dividers bug: the plan presentation and
  the first tagged quiz call usually share ONE assistant message, so
  the message-level seam drew Planning+Teaching back-to-back. New pure
  teachStepIndex(parts) finds the STEP boundary governing the flip
  call; the divider renders there (replacing that boundary's plain
  hairline — a labeled rule supersedes it), prepending before the whole
  message only when the flip is in its first step. The fold (chip,
  sidebar state) is untouched.
- JOBS SUITE, flake round 3: the sweep scans the SHARED jobs dir, so
  parallel test FILES' running records respawn into this file's
  counters — the assertions go jurisdictional (own-job ids collected;
  foreign respawns are not this test's business). 1331/1331.

components/chat.tsx

@@ -50,6 +50,7 @@ import {
 	findPendingToolCall,
 	phaseAt3,
 	phaseTimeline,
+	teachStepIndex,
 	toolQuestionKind,
 	quizNeedsReveal,
 } from "@/src/core";
@@ -1238,15 +1239,26 @@ export function Chat({
 									{/* THE INFERRED TEACH SEAM (owner ruling 2026-09-26, the verdict
 									death): teaching begins where the FIRST nodeId-tagged quiz is
 									posed — the fold (phaseTimeline, the same derivation the phase chip
-									reads) flips to teach exactly AT this assistant group, so the divider
+									reads) flips to teach exactly AT this assistant group. STEP-LEVEL
-									renders BEFORE the whole block (thinking -> prose -> the quiz call) —
+									since owner round 8 (2026-10-05 — the stacked-dividers bug): the
-									where the explicit accept marker used to sit. The boundary check
+									plan presentation often lives in the SAME message, an earlier
-									(this index flips, the previous didn't) guarantees exactly ONE divider
+									provider step than the quiz call, and the old message-level seam
-									per session. PREPENDED, never a replacement branch: the teach group is
+									drew this divider before the plan too (Planning and Teaching
-									a real message with content (the marker branches above have none) — a
+									stacked back-to-back, nothing between). teachStepIndex finds the
-									replacement ternary swallowed the entire first lesson block (the
+									step boundary governing the flip call: -1 = the message's first
-									Lacan session, 2026-09-27). */}
+									step → prepend before the whole block (this branch); a later
-									{m.role === "assistant" && mi > 0 && phases[mi] === "teach" && phases[mi - 1] !== "teach" ? (
+									index → the divider renders AT that part boundary in the loop
+									below (replacing the plain step hairline — a labeled phase rule
+									supersedes it). The boundary check (this index flips, the
+									previous didn't) still guarantees exactly ONE divider per session.
+									PREPENDED, never a replacement branch: the teach group is a real
+									message with content — a replacement ternary swallowed the entire
+									first lesson block (the Lacan session, 2026-09-27). */}
+									{m.role === "assistant" &&
+									mi > 0 &&
+									phases[mi] === "teach" &&
+									phases[mi - 1] !== "teach" &&
+									teachStepIndex(m.parts) === -1 ? (
 										<PhaseDivider key={`teach-${m.id || `m-${mi}`}`} phase="teach" />
 									) : null}
 									{m.role === "user" ? (
@@ -1273,6 +1285,15 @@ export function Chat({
 									<MessageContent className="w-full">
 											{m.parts.map((part, pi) => {
 												const isLastPart = mi === messages.length - 1 && pi === m.parts.length - 1;
+												// The step boundary where teaching begins (round 8): when
+												// the teach flip happens in a LATER step, its PhaseDivider
+												// replaces this boundary's plain hairline.
+												const teachBoundary =
+													m.role === "assistant" &&
+													mi > 0 &&
+													phases[mi] === "teach" &&
+													phases[mi - 1] !== "teach" &&
+													teachStepIndex(m.parts) === pi;
 												// A tool call that errored BACK TO THE AGENT (validation
 												// failure, malformed args) is invisible work — the agent
 												// reads the error and retries. Owner ruling 2026-09-26:
@@ -1302,6 +1323,8 @@ export function Chat({
 															</Reasoning>
 														);
 													case "step-start":
+														if (teachBoundary)
+															return <PhaseDivider key={`teach-step-${pi}`} phase="teach" />;
 														return pi > 0 ? <Separator key={pi} className="my-3" /> : null;
 													case "data-plan-block":
 														// The plan in the chat (wave 4): a frozen snapshot

components/sidebar.tsx

@@ -17,6 +17,7 @@ import { Hint } from "@/components/ui/hint";
 import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
 import { cn } from "@/lib/utils";
+import { fuzzyScore } from "@/src/core";
 import { useServerEvent, useServerResync } from "@/components/server-events";
 import type { ChatListItem } from "@/src/core";
 import { kbdEventForAction } from "@/src/core";
@@ -384,15 +385,22 @@ function SessionsSidebar() {
 		router.push("/chat/new");
 	}, [router]);
 
+	/* FUZZY (owner round 8, 2026-10-05): subsequence match ranked by
+	 * fuzzyScore — prefix beats word-boundary beats scattered. Empty query
+	 * keeps the natural list order (scores are all 0, sort is stable). */
 	const shown = useMemo(() => {
-		const q = query.trim().toLowerCase();
+		const q = query.trim();
 		let list = chats;
 		if (list && kindFilter !== "all") {
 			list = list.filter((c) => (c.kind ?? "teach") === kindFilter);
 		}
 		if (!list) return list;
 		if (!q) return list;
-		return list.filter((c) => c.title.toLowerCase().includes(q));
+		return list
+			.map((c) => ({ c, score: fuzzyScore(q, c.title) }))
+			.filter((r): r is { c: (typeof list)[number]; score: number } => r.score !== null)
+			.sort((a, b) => b.score - a.score)
+			.map((r) => r.c);
 	}, [chats, query, kindFilter]);
 
 	const refreshInFlightRef = useRef(false);
@@ -688,14 +696,16 @@ function SessionsSidebar() {
 					</Hint>
 				</div>
 
-				{/* Two doors (practice sessions, owner 2026-10-04): teaching
+				{/* Two doors, STACKED (owner round 8, 2026-10-05 — was a
-				    keeps the original draft route; practice carries its mode. */}
+				    half/half row): full-width rows read cleaner and give the
-				<div className="mx-3 mb-1 flex gap-1.5">
+				    labels room; teaching keeps the original draft route,
+				    practice carries its mode. */}
+				<div className="mx-3 mb-1 flex flex-col gap-1.5">
 					<button
 						type="button"
 						data-testid="new-session"
 						onClick={() => void newSession()}
-						className="flex flex-1 items-center gap-1.5 rounded-md px-2 py-1.5 text-xs uppercase tracking-wider text-muted-foreground transition-colors hover:bg-accent hover:text-foreground"
+						className="flex w-full items-center gap-1.5 rounded-md px-2 py-1.5 text-xs uppercase tracking-wider text-muted-foreground transition-colors hover:bg-accent hover:text-foreground"
 					>
 						<PlusIcon className="size-3" />
 						Teaching
@@ -705,7 +715,7 @@ function SessionsSidebar() {
 						type="button"
 						data-testid="new-session-practice"
 						onClick={() => router.push("/chat/new?mode=practice")}
-						className="flex flex-1 items-center gap-1.5 rounded-md px-2 py-1.5 text-xs uppercase tracking-wider text-muted-foreground transition-colors hover:bg-accent hover:text-foreground"
+						className="flex w-full items-center gap-1.5 rounded-md px-2 py-1.5 text-xs uppercase tracking-wider text-muted-foreground transition-colors hover:bg-accent hover:text-foreground"
 					>
 						<DumbbellIcon className="size-3" />
 						Practice
@@ -713,10 +723,12 @@ function SessionsSidebar() {
 					</button>
 				</div>
 
-				{/* The three-way filter (owner, 2026-10-04): Teaching / All /
+				{/* The three-way filter (owner, 2026-10-04; order owner round 8,
-				    Practice, quiet segmented, persisted client-side. */}
+				    2026-10-05): Teaching / Practice / All — the two real modes
+				    first, "All" as the escape hatch on the right, mirroring the
+				    stacked create-buttons above. Persisted client-side. */}
 				<div className="mx-3 mb-1.5 flex items-center gap-0.5 rounded-md border border-border/60 bg-background p-0.5" data-testid="session-kind-filter">
-					{(["teach", "all", "practice"] as const).map((f) => (
+					{(["teach", "practice", "all"] as const).map((f) => (
 						<button
 							key={f}
 							type="button"

src/core/phases.ts

@@ -96,6 +96,45 @@ function advance(
 	return phase;
 }
 
+/**
+ * WHERE inside the flipping message teaching begins (owner round 8,
+ * 2026-10-05 — the stacked-dividers bug): plan→teach flips at the first
+ * tagged quiz/explain CALL, but the plan PRESENTATION often lives in the
+ * same assistant message — an earlier provider STEP than the quiz call.
+ * A message-level seam therefore drew the Teaching divider before the
+ * plan presentation too (Planning and Teaching stacked back-to-back).
+ * This returns the part index of the STEP BOUNDARY governing the flip
+ * call: -1 when the call sits in the message's FIRST step (the divider
+ * belongs before the whole message), else the index of the step-start
+ * part whose generation contains the call — the divider renders there,
+ * between the plan presentation and the teaching block.
+ */
+export function teachStepIndex(
+	parts: ReadonlyArray<{ type: string; state?: string; input?: unknown }>,
+): number {
+	let stepStarts = 0; // how many step-start parts seen so far
+	let latest = -1; // index of the latest step-start
+	for (let i = 0; i < parts.length; i++) {
+		const part = parts[i]!;
+		if (part.type === "step-start") {
+			stepStarts++;
+			latest = i;
+			continue;
+		}
+		if (
+			(part.type === "tool-quiz" || part.type === "tool-explain") &&
+			taggedNodeId(part.input)
+		) {
+			// The call's governing step: 0–1 step-starts seen = the message's
+			// FIRST step → -1 (the divider belongs before the whole message);
+			// a later step → that step-start's index (the divider renders at
+			// the boundary, replacing the plain hairline there).
+			return stepStarts <= 1 ? -1 : latest;
+		}
+	}
+	return -1;
+}
+
 /**
  * The phase at EVERY message index, in one forward fold — the transcript
  * dividers render one per boundary, so phaseAt3(m, i) per index would rescan

tests/jobs.test.ts

@@ -1574,13 +1574,18 @@ describe("stale-job recovery sweep (liveness-gated)", () => {
 		// alone must NOT trigger recovery anymore.
 		jobStore.updateJob(jobId, { updatedAt: new Date(Date.now() - 30 * 60_000).toISOString() });
 		registerJobAbort(jobId, new AbortController()); // a loop is executing
-		let respawned = 0;
+		// JURISDICTIONAL (owner round 8, 2026-10-05): the sweep scans the
-		setJobRespawn(() => {
+		// SHARED jobs dir — under the full suite, OTHER FILES' processes
-			respawned++;
+		// legitimately leave running records this sweep may respawn. Only
+		// THIS test's job is this test's business: collect ids, assert ours
+		// never respawns (the counter form saw foreign respawns as failures).
+		const respawnedIds: string[] = [];
+		setJobRespawn((id) => {
+			respawnedIds.push(id);
 		});
 		resetSweepThrottle();
 		recoverStaleJobs();
-		assert.equal(respawned, 0, "a live loop is provably executing — no respawn beside it");
+		assert.ok(!respawnedIds.includes(jobId), "a live loop is provably executing — no respawn beside it");
 		assert.equal(jobStore.getJob(jobId)!.activity, "starting", "the record is untouched");
 		// Hermetic teardown: settle + unregister so later sweeps in THIS suite
 		// never see this fixture as a fresh orphan.
@@ -1590,13 +1595,15 @@ describe("stale-job recovery sweep (liveness-gated)", () => {
 
 	it("a running record WITHOUT a registration is an orphan: the loop is re-spawned immediately (no age wait)", () => {
 		const { jobId } = orphanJob();
-		let respawned: string | null = null;
+		// JURISDICTIONAL (see above): foreign respawns may interleave under
+		// the full suite — ours must be among them, at once.
+		const respawnedIds: string[] = [];
 		setJobRespawn((id) => {
-			respawned = id;
+			respawnedIds.push(id);
 		});
 		resetSweepThrottle();
 		recoverStaleJobs();
-		assert.equal(respawned, jobId, "the orphan's loop is re-spawned at once");
+		assert.ok(respawnedIds.includes(jobId), "the orphan's loop is re-spawned at once");
 		assert.equal(jobStore.getJob(jobId)!.activity, "recovering: re-running");
 		// Hermetic teardown (see above) — the respawned loop is the TEST's
 		// fake seam, nothing real runs.

tests/render-phase-divider.test.tsx

@@ -13,6 +13,7 @@ import assert from "node:assert/strict";
 import { describe, it } from "node:test";
 import { renderToStaticMarkup } from "react-dom/server";
 import { PhaseChip, PhaseDivider, planNodeCount } from "../components/phase-divider.tsx";
+import { teachStepIndex } from "../src/core/phases.ts";
 
 describe("PhaseChip (header)", () => {
 	it("renders the learner-facing label — no colored dot (phase color retired)", () => {
@@ -79,6 +80,53 @@ describe("PhaseDivider (transcript boundary)", () => {
 	});
 });
 
+describe("teachStepIndex (WHERE teaching begins inside the flipping message — owner round 8)", () => {
+	const call = { type: "tool-quiz", input: { nodeId: "n1", question: "q?" } };
+
+	it("the flip call in the message's FIRST step → -1 (divider prepends before the message)", () => {
+		assert.equal(teachStepIndex([{ type: "step-start" }, { type: "text" }, call]), -1);
+	});
+
+	it("a later step: the boundary's step-start index — between plan presentation and teaching", () => {
+		// The stacked-dividers bug shape: plan_init + plan text, then a NEW
+		// step that poses the first tagged quiz. The seam is the SECOND
+		// step-start (index 3), not before the message.
+		const parts = [
+			{ type: "step-start" },
+			{ type: "tool-plan_init", state: "output-available" },
+			{ type: "text", text: "Here is your plan." },
+			{ type: "step-start" },
+			{ type: "text", text: "Let's begin." },
+			call,
+		];
+		assert.equal(teachStepIndex(parts), 3);
+	});
+
+	it("no step-start parts at all (defensive): first step → -1", () => {
+		assert.equal(teachStepIndex([{ type: "text" }, call]), -1);
+	});
+
+	it("an untagged quiz call is not the flip — scan continues to the tagged one", () => {
+		const parts = [
+			{ type: "step-start" },
+			{ type: "tool-quiz", input: { question: "probe quiz — no nodeId" } },
+			{ type: "step-start" },
+			call,
+		];
+		assert.equal(teachStepIndex(parts), 2);
+	});
+
+	it("explain calls carry nodeId too — same seam", () => {
+		const parts = [
+			{ type: "step-start" },
+			{ type: "text" },
+			{ type: "step-start" },
+			{ type: "tool-explain", input: { nodeId: "n2", topic: "t" } },
+		];
+		assert.equal(teachStepIndex(parts), 2);
+	});
+});
+
 describe("planNodeCount (the seam message's tree)", () => {
 	it("counts the first output-available plan tree in the message", () => {
 		const count = planNodeCount({