Plan placement (owner): the plan as marginalia — dock band's right flank + top-bar chip

Retires the fixed bottom-left plan window (which sat ON the sidebar and
bled into the session). Two placements replace it, per the owner's
lock-in:

- The plan chip in the top bar beside the phase chip — session-level
  structure beside session state; opens the full-DAG popup; present at
  every width; the access point.
- The plan marginalia: the BARE diagram (no card, no border, no shadow)
  in the dock band's right flank — marginalia on the lesson's page, not a
  floating widget. The band's reserved height (tall while a quiz is
  open) is its canvas; meet-fitted (PlanDiagram's new fill mode) so it
  fits both the flank's width and the band's height; live statuses +
  the yellow current-node glow; click opens the popup. Mounted only
  while a question owns the band — composer mode keeps the reading
  view pristine. Folding the dock fades + blurs it out of existence
  (300ms), returning to the bottom fades it back in. Rendered only when
  the flank holds a real diagram (>= 240px); narrower windows keep the
  chip alone.

Files: chat.tsx (chip, DockOverlay marginalia wrapper + flank measure,
PlanWindow removed), plan-window.tsx (PlanWindow → PlanMarginalia),
plan-block.tsx (PlanDiagram fill prop: h-full w-full meet-fit),
tests/plan-window.test.tsx (rewritten for the marginalia).

components/chat.tsx

@@ -23,7 +23,8 @@ import { JobsContext } from "@/components/jobs-context";
 import { StatsBar } from "@/components/stats-bar";
 import type { ChatSettings } from "@/src/core";
 import { PlanBlock, PlanPopup, latestTree } from "@/components/plan-block";
-import { PlanWindow } from "@/components/plan-window";
+import { PlanMarginalia } from "@/components/plan-window";
+import { WaypointsIcon } from "lucide-react";
 import type { PlanBlockData } from "@/src/core";
 import { QuestionDock } from "@/components/question-dock";
 import { SidebarToggle } from "@/components/sidebar";
@@ -40,6 +41,14 @@ import { findPendingToolCall, phaseAt3, phaseTimeline } from "@/src/core";
  */
 const COLUMN = "mx-auto w-full max-w-none px-6";
 const DOCK = "mx-auto w-full max-w-[46rem] px-4";
+// The DOCK container's fixed width (46rem) and the plan marginalia's
+// geometry (owner, plan-placement round): the bare diagram sits in the
+// dock band's RIGHT flank — MARGIN_GAP from the DOCK container's edge and
+// the same from the column's right edge. Rendered only when the flank
+// holds a real diagram (no slivers); otherwise the top-bar chip alone.
+const DOCK_W = 46 * 16;
+const MARGIN_GAP = 16;
+const MARGIN_MIN_W = 240;
 // The dock overlay's gradient band (h-24) — part of the reserved tail.
 const GRADIENT_H = 96;
 // Fold thresholds (owner, scroll round 1, tuned round 3): pixel distance
@@ -212,8 +221,12 @@ export function Chat({
 		}
 	}, [chatId, setMessages, sendMessage, status]);
 
-	// The live plan popup (wave 4): opened by any transcript plan block.
+	// The live plan popup (wave 4): opened by any transcript plan block, the
+	// top-bar plan chip, and the dock band's marginalia.
 	const [planOpen, setPlanOpen] = useState(false);
+	// The session's live plan (drives the top-bar chip; the marginalia
+	// derives its own from the same transcript).
+	const planTree = useMemo(() => latestTree(messages), [messages]);
 
 	// ── The plan verdict gate (docs/probe-teach-split.md §4) ──
 	// The plan has been presented (a tree exists) and the session still sits in
@@ -221,8 +234,8 @@ export function Chat({
 	// Accept / Decline buttons. Acceptance is the explicit plan→teach seam
 	// (a data-plan-accepted part on the message); decline asks for revision.
 	const planVerdict = useMemo(
-		() => phaseAt3(messages) === "plan" && latestTree(messages) !== null,
-		[messages],
+		() => phaseAt3(messages) === "plan" && planTree !== null,
+		[messages, planTree],
 	);
 	const sendVerdict = useCallback(
 		(accepted: boolean) => {
@@ -487,6 +500,21 @@ export function Chat({
 				<header className="flex h-10 items-center gap-3 border-b border-border px-3">
 					<SidebarToggle />
 					<div className="min-w-0 flex-1 truncate font-title text-2xl tracking-tight">{title}</div>
+					{/* The plan chip (owner, plan-placement round): session-level
+					    structure beside the phase chip — access to the full-DAG popup
+					    at every width; the marginalia is the wide-screen glance view. */}
+					{planTree && (
+						<button
+							type="button"
+							data-testid="plan-chip"
+							onClick={() => setPlanOpen(true)}
+							title="Open the full plan"
+							className="flex shrink-0 cursor-pointer items-center gap-1.5 rounded-full border border-border/80 px-2 py-0.5 text-xs font-medium uppercase tracking-wide text-muted-foreground transition-colors hover:border-border hover:text-foreground"
+						>
+							<WaypointsIcon className="size-3.5 text-primary" aria-hidden />
+							Plan
+						</button>
+					)}
 					<PhaseChip phase={phases.at(-1) ?? "probe"} />
 				</header>
 
@@ -630,6 +658,8 @@ export function Chat({
 					chatId={chatId}
 					settings={settings}
 					onSettingsSaved={setSettings}
+					plan={<PlanMarginalia messages={messages} />}
+					onOpenPlan={() => setPlanOpen(true)}
 					requiresReveal={requiresReveal}
 					phase={phases.at(-1) ?? "probe"}
 					turns={turns}
@@ -669,8 +699,6 @@ export function Chat({
 			</div>
 		</div>
 		{planOpen && <PlanPopup messages={messages} onClose={() => setPlanOpen(false)} />}
-		{/* The plan's ambient presence: live, zoomed on the current node; click → popup. */}
-		<PlanWindow messages={messages} onOpen={() => setPlanOpen(true)} />
 		</JobsContext.Provider>
 		</ChatActionsContext.Provider>
 	);
@@ -710,6 +738,8 @@ function DockOverlay({
 	settings,
 	onSettingsSaved,
 	onReserve,
+	plan,
+	onOpenPlan,
 }: {
 	pending: ReturnType<typeof findPendingToolCall>;
 	/** Teach-phase pending question: arrives collapsed behind the reveal button (W5). */
@@ -727,6 +757,11 @@ function DockOverlay({
 	/** Reports the dock's settled height (block + gradient) — ChatView's
 	 *  dockReserve state feeds the transcript's spacer from it. */
 	onReserve: (h: number) => void;
+	/** The plan marginalia's content (the bare diagram) — rendered only
+	 *  while a question owns the band. Null until a plan exists. */
+	plan?: React.ReactNode;
+	/** Opens the full-DAG popup (the marginalia + chip share it). */
+	onOpenPlan: () => void;
 }) {
 	const { isAtBottom, scrollToBottom, scrollRef } = useStickToBottomContext();
 	// Teach-phase mount (session reload with a pending check): the dock starts
@@ -773,6 +808,24 @@ function DockOverlay({
 	const revealedRef = useRef(revealed);
 	revealedRef.current = revealed;
 
+	// The plan marginalia's flank width (owner, plan-placement round): from
+	// the DOCK container's right edge to the block's right edge — the bare
+	// diagram's canvas. Re-measured every render (cheap offsetWidth read):
+	// window resizes flow through sbInset's listener, and the sidebar toggle
+	// re-renders the column without any event at all. Below MARGIN_MIN_W the
+	// margin is no margin — the chip alone carries the plan.
+	const [flankW, setFlankW] = useState(0);
+	const flankWRef = useRef(0);
+	useIsoLayoutEffect(() => {
+		const block = blockRef.current;
+		if (!block) return;
+		const next = Math.round(block.offsetWidth / 2 - DOCK_W / 2 - 2 * MARGIN_GAP);
+		if (Math.abs(next - flankWRef.current) > 1) {
+			flankWRef.current = next;
+			setFlankW(next);
+		}
+	});
+
 	// The overlay must not paint over the scroller's scrollbar (owner, scroll
 	// round 2): the scroller reserves symmetric gutters (scrollbar-gutter:
 	// stable both-edges), so inset the overlay's right edge by the gutter —
@@ -921,7 +974,7 @@ function DockOverlay({
 	return (
 		<div className="pointer-events-none absolute inset-x-0 bottom-0" style={{ right: sbInset }}>
 			<div className="h-24 bg-gradient-to-t from-background via-background/85 to-transparent" />
-			<div ref={blockRef} className="bg-background pb-5">
+			<div ref={blockRef} className="relative bg-background pb-5">
 				<div className={DOCK}>
 					<div ref={shellRef} className="pointer-events-auto overflow-hidden rounded-2xl border bg-card shadow-lg">
 						<div key={mode} className={mode === initialModeRef.current ? undefined : "dock-variant"}>
@@ -951,6 +1004,26 @@ function DockOverlay({
 						onSettingsSaved={onSettingsSaved}
 					/>
 				</div>
+				{/* The plan marginalia (owner, plan-placement round): the bare
+				    diagram in the band's right flank — boundaless, meet-fitted, part
+				    of the lesson's page rather than a floating widget. Mounted only
+				    while a question owns the band (its reserved height is the canvas);
+				    folding the dock fades + blurs it out of existence, so reading
+				    the transcript in full wipes the margin clean. Click → popup. */}
+				{pending && plan && flankW >= MARGIN_MIN_W && (
+					<button
+						type="button"
+						data-testid="plan-marginalia"
+						onClick={onOpenPlan}
+						title="Open the full plan"
+						style={{ left: `calc(50% + ${DOCK_W / 2 + MARGIN_GAP}px)` }}
+						className={`absolute bottom-5 right-4 top-0 cursor-pointer transition-[filter,opacity] duration-300 ease-out ${
+							expanded ? "pointer-events-auto opacity-100 blur-0" : "pointer-events-none opacity-0 blur-md"
+						}`}
+					>
+						{plan}
+					</button>
+				)}
 			</div>
 		</div>
 	);

components/plan-block.tsx

@@ -358,6 +358,7 @@ export function PlanDiagram({
 	textCapScale,
 	naturalSize,
 	monochrome,
+	fill,
 }: {
 	nodes: readonly LayoutNode[];
 	edges: ReadonlyArray<{ from: string; to: string }>;
@@ -379,6 +380,11 @@ export function PlanDiagram({
 	/** The in-chat block's mode: every node white (fill-none, white stroke
 	 *  and text, no glow) — statuses never show in the transcript (owner). */
 	monochrome?: boolean;
+	/** Meet-fits the diagram inside a fixed box (h-full w-full — the svg's
+	 *  default preserveAspectRatio centers + contains the viewBox): the
+	 *  dock band's marginalia mode, where the diagram must fit BOTH the
+	 *  flank's width and the band's height rather than run width-first. */
+	fill?: boolean;
 }) {
 	const layout = useMemo(() => blockLayout(nodes, edges), [nodes, edges]);
 	// Pad only the full-extent render — the plan window's override viewBox is
@@ -391,7 +397,7 @@ export function PlanDiagram({
 	return (
 		<svg
 			viewBox={viewBoxOverride ?? `${-pad} ${-pad} ${vbW} ${vbH}`}
-			className={`block h-auto${naturalSize ? "" : " w-full"}${textCapScale ? " mx-auto" : ""}`}
+			className={`block ${fill ? "h-full w-full" : `h-auto${naturalSize ? "" : " w-full"}`}${textCapScale ? " mx-auto" : ""}`}
 			style={
 				textCapScale
 					? { maxWidth: `${Math.round(vbW * textCapScale * 100) / 100}px` }

components/plan-window.tsx

@@ -1,102 +1,54 @@
 "use client";
 
 import { useId, useMemo } from "react";
-import { WaypointsIcon } from "lucide-react";
-import type { PlanTree } from "@/src/core";
 import { derivedNodeStatus, derivePlanStatuses } from "@/src/core";
 import {
 	PlanDiagram,
-	blockLayout,
+	GRAPH_PAD,
 	latestTree,
-	NODE_H,
-	NODE_W,
+	TEXT_CAP_SCALE,
 	type PopupMessage,
 } from "@/components/plan-block";
 
 /**
- * THE PLAN WINDOW (docs/probe-teach-split.md §6): the plan's persistent,
- * ambient presence — the successor of the injected plan blocks. Always on
- * once a tree exists, it shows a ZOOMED-IN window on the CURRENT node and
- * moves by itself as the lesson advances (auto-pan: the viewBox re-centers
- * on the latest tagged check — no animation machinery, the window just
- * follows the derived position). Click opens the full-DAG popup.
+ * THE PLAN MARGINALIA: the plan's ambient presence in the session view —
+ * the successor of the old fixed corner card (the plan window, retired
+ * with the dock-band placement round). NO container: the bare diagram,
+ * meet-fitted into the dock band's right flank — the wrapper (DockOverlay)
+ * positions and fades it — so it reads as marginalia on the lesson's
+ * page, not a floating widget. Live by construction: statuses derive from
+ * the transcript on every render (derivePlanStatuses — calls, not
+ * results), so the glow moves the moment a tagged check streams in.
  *
- * Live by construction: statuses derive from the transcript on every
- * render (derivePlanStatuses — calls, not results), so the window moves
- * the moment a tagged check call streams in or a record adoption lands.
- * Hidden on narrow viewports (the dock owns that corner's collapse
- * pattern); the learner's visual polish pass (colors, motion) comes later.
+ * Visibile only while a question owns the dock band (the reserved tail's
+ * height is the diagram's canvas — quiz open, tall band, full plan);
+ * folding the dock fades + blurs the whole thing out of existence. The
+ * top-bar plan chip carries access at every width; the popup is the study
+ * view. The viewBox pad clears the current node's blurred yellow halo
+ * (GLOW_REACH) at the extent edges.
  */
 
-/** Window dimensions in SVG units — 2:1, ~2¼ node widths: the current
- *  node plus its immediate neighborhood. Aspect-matched to the card. */
-const VIEW_W = 360;
-const VIEW_H = 180;
+const MARGIN_PAD = GRAPH_PAD + 16;
 
-/**
- * The windowed viewBox, centered on the current node — pure (exported for
- * tests). Falls back to the FIRST node (authoring order — the lesson's
- * start) while no check has been tagged. A layout smaller than the window
- * centers itself; a larger one clamps so the window never strays into
- * empty space beyond an edge node.
- */
-export function planWindowViewBox(tree: PlanTree, current: string | null): string {
-	const layout = blockLayout(tree.nodes, tree.edges);
-	const focusId =
-		current && layout.x.has(current)
-			? current
-			: (tree.nodes[0]?.id ?? null);
-	const cx =
-		focusId !== null
-			? (layout.x.get(focusId) ?? 0) + NODE_W / 2
-			: Math.max(layout.width, 1) / 2;
-	const cy =
-		focusId !== null
-			? (layout.y.get(focusId) ?? 0) + (layout.nodeH.get(focusId) ?? NODE_H) / 2
-			: Math.max(layout.height, 1) / 2;
-	const clamp = (c: number, extent: number, view: number) =>
-		extent <= view ? extent / 2 : Math.min(Math.max(c, view / 2), extent - view / 2);
-	const x = clamp(cx, layout.width, VIEW_W) - VIEW_W / 2;
-	const y = clamp(cy, layout.height, VIEW_H) - VIEW_H / 2;
-	return `${x} ${y} ${VIEW_W} ${VIEW_H}`;
-}
-
-export function PlanWindow({ messages, onOpen }: { messages: readonly PopupMessage[]; onOpen: () => void }) {
+export function PlanMarginalia({ messages }: { messages: readonly PopupMessage[] }) {
 	const markerId = useId().replace(/[^a-zA-Z0-9-]/g, "");
 	const tree = useMemo(() => latestTree(messages), [messages]);
 	const statuses = useMemo(
 		() => (tree ? derivePlanStatuses(tree, messages as Parameters<typeof derivePlanStatuses>[1]) : null),
 		[tree, messages],
 	);
-	if (!tree || tree.nodes.length === 0) return null; // no plan yet: no window
+	if (!tree || tree.nodes.length === 0) return null; // no plan yet: nothing in the margin
 	const statusOf = (id: string) => (statuses ? derivedNodeStatus(statuses, id) : "upcoming");
-	const currentTitle = statuses?.current
-		? (tree.nodes.find((n) => n.id === statuses.current)?.title ?? null)
-		: null;
-
 	return (
-		<button
-			type="button"
-			data-testid="plan-window"
-			onClick={onOpen}
-			title="Open the full plan"
-			className="fixed bottom-3 left-3 z-30 hidden w-80 flex-col gap-1 rounded-xl border bg-card/95 p-2 text-left shadow-lg backdrop-blur sm:flex"
-		>
-			<div className="flex items-center gap-2 px-1 text-xs font-medium uppercase tracking-wide text-muted-foreground">
-				<WaypointsIcon className="size-3.5 text-primary" />
-				The plan
-				<span className="ml-auto min-w-0 truncate font-normal normal-case" title={currentTitle ?? undefined}>
-					{currentTitle ?? "starting"}
-				</span>
-			</div>
-			<PlanDiagram
-				nodes={tree.nodes}
-				edges={tree.edges}
-				statusOf={statusOf}
-				glowId={statuses?.current ?? null}
-				markerId={markerId}
-				viewBoxOverride={planWindowViewBox(tree, statuses?.current ?? null)}
-			/>
-		</button>
+		<PlanDiagram
+			nodes={tree.nodes}
+			edges={tree.edges}
+			statusOf={statusOf}
+			glowId={statuses?.current ?? null}
+			markerId={markerId}
+			pad={MARGIN_PAD}
+			textCapScale={TEXT_CAP_SCALE}
+			fill
+		/>
 	);
-}
+}

tests/plan-window.test.tsx

@@ -1,13 +1,13 @@
 import { renderToStaticMarkup } from "react-dom/server";
 import { describe, it } from "node:test";
 import assert from "node:assert/strict";
-import { planWindowViewBox, PlanWindow } from "../components/plan-window.tsx";
-import { blockLayout, NODE_H, NODE_W, type PopupMessage } from "../components/plan-block.tsx";
+import { PlanMarginalia } from "../components/plan-window.tsx";
+import { blockLayout, type PopupMessage } from "../components/plan-block.tsx";
 import type { PlanTree } from "../src/core/contracts.ts";
 
-// The plan window: the ambient live view — a windowed viewBox centered on
-// the current node (auto-pan by derivation, not animation), full plan
-// hidden until a tree exists, click → popup.
+// The plan marginalia: the bare diagram in the dock band's right flank —
+// full plan (padded viewBox, meet-fit), statuses + glow live by derivation,
+// nothing until a tree exists. Positioning and fade live in DockOverlay.
 
 const CHAIN: PlanTree = {
 	nodes: [
@@ -44,68 +44,34 @@ function transcript(tree: PlanTree, taggedNodeId?: string): PopupMessage[] {
 	];
 }
 
-describe("planWindowViewBox (pure)", () => {
-	it("centers the window on the current node", () => {
-		const layout = blockLayout(CHAIN.nodes, CHAIN.edges);
-		const cy = layout.y.get("b")! + NODE_H / 2; // chain: all x = 0
-		const vb = planWindowViewBox(CHAIN, "b").split(" ").map(Number);
-		assert.equal(vb[3], 180); // 2:1 window
-		assert.equal(vb[1]! + 90, cy, "vertical center = node b's center");
-		// layout narrower than the window → centered on the (single-column) layout
-		assert.equal(vb[0]! + 180, layout.width / 2);
+describe("PlanMarginalia render", () => {
+	it("renders nothing until a tree exists", () => {
+		assert.equal(renderToStaticMarkup(<PlanMarginalia messages={[]} />), "");
 	});
 
-	it("falls back to the first node while no check has been tagged — clamped at the layout's top edge", () => {
+	it("renders the FULL plan (padded full-extent viewBox), not a windowed crop", () => {
+		const html = renderToStaticMarkup(<PlanMarginalia messages={transcript(CHAIN)} />);
+		// The viewBox covers the whole layout plus the glow-clearing pad —
+		// never the retired window's 2:1 crop.
 		const layout = blockLayout(CHAIN.nodes, CHAIN.edges);
-		const vb = planWindowViewBox(CHAIN, null).split(" ").map(Number);
-		// Focusing row 0 would center half-off the layout; the clamp pins the
-		// window to the top edge instead — node a stays fully inside it.
-		assert.equal(vb[1], 0);
-		const aTop = layout.y.get("a")!;
-		assert.ok(aTop >= vb[1] && aTop + NODE_H <= vb[1] + 180, "the first node is inside the window");
+		const pad = 24; // MARGIN_PAD: GRAPH_PAD + 16 (glow halo clearance)
+		const vb = `viewBox="${-pad} ${-pad} ${layout.width + 2 * pad} ${layout.height + 2 * pad}"`;
+		assert.ok(html.includes(vb), `expected ${vb} in the svg`);
+		assert.ok(!/viewBox="-?\d+(\.\d+)? -?\d+(\.\d+)? 360 180"/.test(html), "the windowed viewBox is retired");
+		// Meet-fit mode: the svg fills the band box (h-full w-full), letting
+		// preserveAspectRatio contain the diagram in the flank.
+		assert.ok(html.includes('class="block h-full w-full'), "fill mode classes");
 	});
 
-	it("clamps along wide rows — the window never strays past an edge node", () => {
-		const wide: PlanTree = {
-			nodes: [
-				{ id: "r1", title: "R1" },
-				{ id: "r2", title: "R2" },
-				{ id: "r3", title: "R3" },
-				{ id: "t", title: "T" },
-			],
-			edges: [
-				{ from: "r1", to: "t" },
-				{ from: "r2", to: "t" },
-				{ from: "r3", to: "t" },
-			],
-			version: 1,
-		};
-		const layout = blockLayout(wide.nodes, wide.edges);
-		assert.ok(layout.width > 360, "fixture: a row wider than the window");
-		// Rightmost root: window's right edge must not exceed the layout width.
-		const vb = planWindowViewBox(wide, "r3").split(" ").map(Number);
-		assert.ok(vb[0]! + 360 <= layout.width + 0.001, "clamped at the right edge");
-		// Leftmost root: window's left edge must not go negative.
-		const vb2 = planWindowViewBox(wide, "r1").split(" ").map(Number);
-		assert.ok(vb2[0]! >= -0.001, "clamped at the left edge");
+	it("glows the current node and dims the not-yet-visited (live statuses)", () => {
+		const html = renderToStaticMarkup(<PlanMarginalia messages={transcript(CHAIN, "b")} />);
+		// The yellow blurred halo marks the tagged check's node…
+		assert.ok(html.includes("fill-yellow-400/25"), "glow on the current node");
+		assert.ok(html.includes('data-testid="plan-node-b" data-status="current"'), "b is current");
+		// …and arrows into upcoming nodes carry the dimmed head.
+		assert.ok(
+			html.includes("url(#:r0:-dim)") || /url\(#\S*-dim\)/.test(html),
+			"dimmed arrowhead into the upcoming node",
+		);
 	});
 });
-
-describe("PlanWindow render", () => {
-	it("hidden while no plan exists", () => {
-		assert.equal(renderToStaticMarkup(<PlanWindow messages={[]} onOpen={() => {}} />), "");
-	});
-
-	it("with a plan: renders windowed, glowing current from the latest tagged call; click target present", () => {
-		const html = renderToStaticMarkup(<PlanWindow messages={transcript(CHAIN, "b")} onOpen={() => {}} />);
-		assert.ok(html.includes('data-testid="plan-window"'));
-		assert.ok(html.includes('data-status="current"'));
-		assert.ok(html.includes('data-status="upcoming"'));
-		// the viewBox is windowed (not the full layout extent)
-		assert.ok(/viewBox="-?\d+(\.\d+)? -?\d+(\.\d+)? 360 180"/.test(html));
-		// no current yet → first node is the fallback focus, header says starting
-		const html2 = renderToStaticMarkup(<PlanWindow messages={transcript(CHAIN)} onOpen={() => {}} />);
-		assert.ok(html2.includes("starting"));
-		assert.ok(!html2.includes('data-status="current"'), "nothing current before the first tagged check");
-	});
-});