Minimal-color round 1 (owner): phase color retired — the braille spinner is the one working indicator

Nothing exists purely for decoration: phase color-coding is retired
app-wide (phases only advance — every session ends Teaching — so
phase-as-signal was decoration with a one-time function), and what
state genuinely deserved — 'a turn is in flight' — is now carried by
MOTION alone, in the terminal's own glyph language.

- BrailleSpinner (components/braille-spinner.tsx): the canonical
  cli-spinner sequence (⠋⠙⠹⠸⠼⠴⠦⠧⠇⠏) as exact dot bitmaps in a 2×4
  braille cell, 80ms/frame (800ms cycle). Pure CSS: one shared keyframes,
  frames staggered via animation-delay; no JS timer, no re-render per
  frame — cheaper than the old breathing dot. Static contexts (SSR,
  prefers-reduced-motion) show frame 0 — a legible glyph, not a blank.
- Sidebar rows: spinner ONLY while a teach turn is in flight; idle and
  question-pending render NOTHING (a resting state has no scan value —
  the meta line's 'Waiting for your answer' text carries it). The
  three-state phase dot (pulse/solid/hollow) and PHASE_FILL/RING maps
  are gone.
- Top bar PhaseChip: label-only pill; the old dot slot becomes the
  spinner's home while a turn is in flight (busy prop wired from
  ChatView's busy = localStream || turnInFlight). Transcript
  PhaseDividers drop phase colors for monochrome rules + labels.
- API narrowing (app/api/chats/route.ts + ChatListItem contract):
  busy = isTurnRunning ONLY — background jobs no longer count (the
  sidebar's Background agents section is their channel; a per-row
  spinner would double-signal them).
- globals.css: --phase-* tokens + lh-dot-breathe removed (dead after
  the sweep — no remaining users).

Live-verified: idle/pending rows render no indicator, /chat/new chip is
label-only, 10 CSSAnimations at 800ms with correct 80ms stagger, static
frame 0 under reduced motion. Gates: typecheck, lint, 470/470, build.

Lane crossings to flag at merge: app/api/chats/route.ts + the
ChatListItem contract comment (src/core) — the busy-semantics narrowing;
components/chat.tsx one-line busy prop.

components/sidebar.tsx

@@ -5,10 +5,11 @@ import Link from "next/link";
 import { usePathname, useRouter } from "next/navigation";
 import { PanelLeftCloseIcon, PanelLeftOpenIcon, PlusIcon, SearchIcon } from "lucide-react";
 import { ActivitySection } from "@/components/activity-dock";
+import { BrailleSpinner } from "@/components/braille-spinner";
 import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
 import { cn } from "@/lib/utils";
-import type { ChatListItem, Phase3 } from "@/src/core";
+import type { ChatListItem } from "@/src/core";
 
 /**
  * Toggleable sidebar — NOT a modal drawer: no backdrop, no focus theft. It
@@ -67,62 +68,20 @@ export function SidebarToggle() {
 	);
 }
 
-/** Phase colors for the session dot — one system with the header chip
- *  and the transcript dividers (globals.css --phase-*). Static class
- *  strings per phase: Tailwind can't compile dynamic class names. */
-const PHASE_FILL: Record<Phase3, string> = {
-	probe: "bg-phase-probe",
-	plan: "bg-phase-plan",
-	teach: "bg-phase-teach",
-};
-const PHASE_RING: Record<Phase3, string> = {
-	probe: "border-phase-probe",
-	plan: "border-phase-plan",
-	teach: "border-phase-teach",
-};
-
 /**
- * The session dot, left of the title. TWO channels, one dot: COLOR is the
- * phase (probe/plan/teach — sky/violet/emerald), FILL+MOTION is what's
- * owed. Pulsing = the teacher is working (rare, time-sensitive — the only
- * state that deserves motion). Solid = a question awaits the learner's
- * answer (the DOMINANT resting state of real sessions — calm by design,
- * no animation). Hollow = nothing owed, idle. A pending answer outranks
- * "working": if a question is owed, that's the blocking fact.
+ * The row's status indicator (owner, minimal-color round): the braille
+ * spinner, ONLY while a teach turn is in flight — monochrome motion, the
+ * terminal's own glyph, existing exactly as long as the work does and
+ * vanishing the moment it ends. Every other state renders NOTHING:
+ * phases only advance (all sessions end in Teaching — phase-as-signal was
+ * decoration, now retired app-wide), and question-pending is the dominant
+ * RESTING state of real sessions — a resting state has no scan value, so
+ * the meta line's "Waiting for your answer" text carries it. Idle is the
+ * absence of a signal, by design.
  */
-function SessionDot({ phase, pending, busy }: { phase: Phase3; pending: boolean; busy: boolean }) {
-	if (pending) {
-		return (
-			<span
-				data-testid="session-dot-awaiting"
-				title="Waiting for your answer"
-				className={cn("size-2 shrink-0 rounded-full", PHASE_FILL[phase])}
-			>
-				<span className="sr-only">Waiting for your answer</span>
-			</span>
-		);
-	}
-	if (busy) {
-		return (
-			<span
-				data-testid="session-dot-working"
-				title="Teacher is working"
-				className={cn("size-2 shrink-0 rounded-full", PHASE_FILL[phase], "lh-dot-breathe")}
-			>
-				<span className="sr-only">Teacher is working</span>
-			</span>
-		);
-	}
-	return (
-		<span
-			data-testid="session-dot-idle"
-			aria-hidden
-			className={cn(
-				"size-2 shrink-0 rounded-full border-2 bg-transparent",
-				PHASE_RING[phase],
-			)}
-		/>
-	);
+function SessionStatus({ busy }: { busy: boolean }) {
+	if (!busy) return null;
+	return <BrailleSpinner />;
 }
 
 /** Compact "how long ago": "just now", "5m ago", "3h ago", "2d ago",
@@ -150,8 +109,9 @@ function sessionMeta(chat: ChatListItem): string {
 }
 
 /**
- * One session row: the status dot, then title + state-aware meta. Exported
- * for render tests — pure function of the list item.
+ * One session row: the status spinner (only while working), then title +
+ * state-aware meta. Exported for render tests — pure function of the
+ * list item.
  */
 export function SessionRow({
 	chat,
@@ -171,7 +131,7 @@ export function SessionRow({
 				active && "bg-accent font-medium",
 			)}
 		>
-			<SessionDot phase={chat.phase} pending={chat.pendingQuestion} busy={chat.busy} />
+			<SessionStatus busy={chat.busy} />
 			<span className="min-w-0 flex-1">
 				<span className="block truncate">{chat.title}</span>
 				<span className="block text-xs text-muted-foreground">{sessionMeta(chat)}</span>