feat(workspace): guide tonight's first labeled handoff on map and player

AGENTS.md

@@ -83,6 +83,7 @@ This section applies to any agent (Claude, Codex, Cursor, opencode, ...) working
 - Keep UI and analysis engine decoupled through shared contracts.
 - Prefer minimal, test-first changes for production code.
 - Prefer practical, friendly, rehearsal-first wording over academic or authority-heavy language.
+- Name tonight's first labeled handoff with the holding part when an active role is corroborated, the labeled pass, and the time so the next action is obvious.
 - Do not reduce the product to a chord analyzer when form, timing, player coordination, playable ranges, simplification, and setup cues are the real rehearsal blockers.
 - Do not frame usability as a reason to accept weak analysis quality; BandScope should aim for both easy use and high accuracy.
 

ARCHITECTURE.md

@@ -6,6 +6,7 @@ Last updated: 2026-03-11
 
 - Product identity, UX tone, copy rules, and prioritization tie-breakers live in `docs/brand-story.md`.
 - Future PRDs, TRDs, onboarding copy, empty states, error messages, and marketing copy should use that document as the single brand source of truth.
+- Workspace and player copy for tonight's first labeled handoff must name the holding part when corroborated, the labeled pass, and the time so the next action is obvious.
 
 ## Security source
 

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### Added
 
+- Name tonight's first labeled handoff on the workspace and player so the room can catch the pass; the workspace action opens the matching map section, while the player exposes a Hear action only when its owning playback surface supplies a seek callback.
 - Name tonight's first playable range on the ready rehearsal map and tell the player to check that span on their instrument before the section.
 - Display the analyzed song tempo (BPM) as a badge in the rehearsal workspace.
 - 각 합주 역할(Role)별 개인 연습 진행도를 0~100% 범위로 기록 및 시각화할 수 있는 연습 진척도(`practiceProgress`) 트래커 기능 추가. UI 컨트롤(슬라이더 및 +/- 버튼)과 한/영 다국어 지원 포함.

CLAUDE.md

@@ -51,7 +51,7 @@ BandScope is a local-first desktop app for rehearsal prep: it turns a song into
 
 Three layers, decoupled through shared contracts:
 
-- `apps/desktop` — Tauri 2 + Vite + React 19 shell (Tailwind 4, Base UI, Storybook). Feature screens live in `src/features/` (home, workspace, chords, ranges, player, settings). The ready workspace names tonight's first playable range and the next instrument check. `src/lib/analysis.ts` and `src/lib/job_runner.ts` call typed Tauri IPC commands, with a browser fallback that serves demo data when not running inside Tauri.
+- `apps/desktop` — Tauri 2 + Vite + React 19 shell (Tailwind 4, Base UI, Storybook). Feature screens live in `src/features/` (home, workspace, chords, ranges, player, settings). Workspace and player name tonight's first labeled handoff so the room can catch the pass; the workspace action opens the matching map section, while the player exposes a Hear action only when its owning playback surface supplies a seek callback. The ready workspace also names tonight's first playable range and the next instrument check. `src/lib/analysis.ts` and `src/lib/job_runner.ts` call typed Tauri IPC commands, with a browser fallback that serves demo data when not running inside Tauri.
 - `apps/desktop/src-tauri/src/main.rs` — the Rust orchestration boundary. Tauri commands (`start_analysis_job`, `get_analysis_job_status`, `select_local_audio_source`, `import_youtube_url`) validate untrusted input (project IDs, file paths, URLs) and spawn the Python engine as a subprocess. There is no loopback HTTP listener and no network path for local analysis.
 - `services/analysis-engine` — Python package `bandscope_analysis` (librosa/numpy). Entry point `cli.py` reads a JSON job request on stdin and prints a structured job-status JSON envelope on stdout (`--progress-jsonl` streams progress lines). `api.py` orchestrates the pipeline across the `separation`, `sections`, `roles`, `chords`, `ranges`, `temporal`, `transcription`, and `youtube` modules.
 

apps/desktop/src/features/player/index.test.tsx

@@ -0,0 +1,97 @@
+import { fireEvent, render, screen } from "@testing-library/react";
+import { createDemoRehearsalSong } from "@bandscope/shared-types";
+import { describe, expect, it, vi } from "vitest";
+import { PlayerFeature } from "./index";
+
+function songWithHandoff() {
+  const song = createDemoRehearsalSong();
+  const verse = song.sections[0]!;
+  const handoff = structuredClone(verse);
+  handoff.id = "handoff-1";
+  handoff.label = "handoff";
+  handoff.timeRange = { start: 22, end: 24 };
+  handoff.roles = [
+    {
+      ...verse.roles[2]!,
+      id: "lead-vocal",
+      name: "Lead Vocal",
+      rehearsalPriority: "high"
+    }
+  ];
+  handoff.partGraph = [
+    {
+      role_id: "lead-vocal",
+      is_active: true,
+      handoff_to: [],
+      handoff_from: []
+    }
+  ];
+  song.sections = [verse, handoff];
+  return song;
+}
+
+describe("PlayerFeature", () => {
+  it("asks the room to analyze first when no song is loaded", () => {
+    render(<PlayerFeature title="Player" />);
+    expect(
+      screen.getByText("Analyze tonight's song first, then hear the first handoff from this player.")
+    ).toBeTruthy();
+  });
+
+  it("keeps the handoff hear action unavailable without a player playback callback", () => {
+    render(<PlayerFeature title="Player" song={songWithHandoff()} />);
+
+    expect(screen.queryByRole("button", { name: "Hear Lead Vocal pass at 0:22" })).toBeNull();
+    expect(screen.getByText("Lead Vocal passes the handoff at 0:22.")).toBeTruthy();
+  });
+
+  it("delegates the handoff hear action to the owning player callback", () => {
+    const onPlayFromSeconds = vi.fn();
+    render(<PlayerFeature title="Player" song={songWithHandoff()} onPlayFromSeconds={onPlayFromSeconds} />);
+
+    fireEvent.click(screen.getByRole("button", { name: "Hear Lead Vocal pass at 0:22" }));
+
+    expect(onPlayFromSeconds).toHaveBeenCalledTimes(1);
+    expect(onPlayFromSeconds).toHaveBeenCalledWith(22);
+  });
+
+  it("renders a safe empty summary when the runtime section collection is not an array", () => {
+    const song = songWithHandoff();
+    (song as unknown as { sections: unknown }).sections = null;
+
+    render(<PlayerFeature title="Player" song={song} />);
+
+    expect(screen.getByText("No handoff yet. Stay on tonight's map until a pass is marked.")).toBeTruthy();
+    expect(screen.getByText("0 sections")).toBeTruthy();
+  });
+
+  it("renders a safe empty summary when the runtime section collection is sparse", () => {
+    const song = songWithHandoff();
+    const sparseSections: typeof song.sections = new Array(2);
+    sparseSections[1] = song.sections[1]!;
+    song.sections = sparseSections;
+
+    render(<PlayerFeature title="Player" song={song} />);
+
+    expect(screen.getByText("No handoff yet. Stay on tonight's map until a pass is marked.")).toBeTruthy();
+    expect(screen.getByText("0 sections")).toBeTruthy();
+  });
+
+  it("omits malformed runtime section elements without crashing the player summary", () => {
+    const song = songWithHandoff();
+    song.sections = [null, song.sections[0]!] as unknown as typeof song.sections;
+
+    render(<PlayerFeature title="Player" song={song} />);
+
+    expect(screen.getByText("1 section")).toBeTruthy();
+    expect(screen.getByText("verse")).toBeTruthy();
+  });
+
+  it("does not pass an object-valued runtime song title into React copy", () => {
+    const song = songWithHandoff();
+    (song as unknown as { title: unknown }).title = { unsafe: "not-copy" };
+
+    expect(() => render(<PlayerFeature title="Player" song={song} />)).not.toThrow();
+    expect(screen.queryByText("not-copy")).toBeNull();
+  });
+});

apps/desktop/src/features/player/index.tsx

@@ -1,46 +1,96 @@
-import type { RehearsalSong } from "@bandscope/shared-types";
+import {
+  SECTION_FORM_LABELS,
+  type RehearsalSection,
+  type RehearsalSong,
+  type SectionFormLabel
+} from "@bandscope/shared-types";
+import { FirstHandoffCallout } from "../workspace/FirstHandoffCallout";
+import { createTranslator, detectPreferredLocale } from "../../i18n";
 
-/** Documented. */
-export function PlayerFeature(props: { title: string; song?: RehearsalSong | null }) {
-  const { title, song } = props;
+type PlayerFeatureProps = {
+  title: string;
+  song?: RehearsalSong | null;
+  onPlayFromSeconds?: (startSeconds: number) => void;
+};
+
+/** Return whether one runtime section is safe to summarize in the player. */
+function isPlayerSummarySection(value: unknown): value is RehearsalSection {
+  if (value === null || typeof value !== "object") {
+    return false;
+  }
+  const section = value as Partial<RehearsalSection>;
+  return (
+    typeof section.id === "string" &&
+    section.id.trim().length > 0 &&
+    typeof section.label === "string" &&
+    SECTION_FORM_LABELS.includes(section.label as SectionFormLabel)
+  );
+}
+
+/** Return dense, individually valid sections without trusting runtime collection metadata. */
+function playerSummarySections(song: RehearsalSong): RehearsalSection[] {
+  const sections = song.sections as unknown;
+  if (!Array.isArray(sections)) {
+    return [];
+  }
+  const length = Number(sections.length);
+  if (!Number.isSafeInteger(length) || length < 0 || length > 0xffffffff) {
+    return [];
+  }
+  for (let index = 0; index < length; index += 1) {
+    if (!(index in sections)) {
+      return [];
+    }
+  }
+  return sections.filter(isPlayerSummarySection);
+}
+
+/** Player surface that names tonight's first labeled handoff and delegates playback to the owning player. */
+export function PlayerFeature({ title, song, onPlayFromSeconds }: PlayerFeatureProps) {
+  const t = createTranslator(detectPreferredLocale());
 
   if (!song) {
     return (
       <section style={{ padding: "24px" }}>
         <h2>{title}</h2>
-        <p style={{ color: "#999" }}>No song loaded. Start an analysis to use the player.</p>
+        <p style={{ color: "#999" }}>{t("firstHandoffNeedsSong")}</p>
       </section>
     );
   }
 
+  const sections = playerSummarySections(song);
+  const songTitle = typeof song.title === "string" ? song.title : "";
+
   return (
     <section style={{ padding: "24px" }}>
       <h2>{title}</h2>
+      <FirstHandoffCallout song={song} actionMode="callback-only" onHearHandoff={onPlayFromSeconds} />
       <div
         style={{
           padding: "16px",
           backgroundColor: "#fafafa",
           borderRadius: "8px",
           border: "1px solid #e8e8e8",
+          marginTop: "16px"
         }}
       >
         <div style={{ marginBottom: "12px" }}>
-          <strong>{song.title}</strong>
+          <strong>{songTitle}</strong>
           <span style={{ color: "#666", marginLeft: "8px" }}>
-            {song.sections.length} {song.sections.length === 1 ? "section" : "sections"}
+            {sections.length} {sections.length === 1 ? "section" : "sections"}
           </span>
         </div>
         <div style={{ display: "flex", gap: "8px", flexWrap: "wrap" }}>
-          {song.sections.map((section) => (
+          {sections.map((section, sectionIndex) => (
             <span
-              key={section.id}
+              key={`${section.id}-${sectionIndex}`}
               style={{
                 padding: "4px 12px",
                 borderRadius: "16px",
                 backgroundColor: "#fff",
                 border: "1px solid #d9d9d9",
                 fontSize: "0.85em",
-                textTransform: "capitalize",
+                textTransform: "capitalize"
               }}
             >
               {section.label}

apps/desktop/src/features/workspace/FirstHandoffCallout.invalid-song-root.test.tsx

@@ -0,0 +1,16 @@
+import { render, screen } from "@testing-library/react";
+import type { RehearsalSong } from "@bandscope/shared-types";
+import { describe, expect, it } from "vitest";
+import { FirstHandoffCallout } from "./FirstHandoffCallout";
+
+/** Cast runtime input through the static song contract to exercise the renderer trust boundary. */
+function runtimeSong(value: unknown): RehearsalSong {
+  return value as RehearsalSong;
+}
+
+describe("FirstHandoffCallout malformed song root", () => {
+  it("renders unavailable guidance instead of crashing when the runtime song root is null", () => {
+    expect(() => render(<FirstHandoffCallout song={runtimeSong(null)} />)).not.toThrow();
+    expect(screen.getByText("No handoff yet. Stay on tonight's map until a pass is marked.")).toBeTruthy();
+  });
+});

apps/desktop/src/features/workspace/FirstHandoffCallout.reduced-motion.test.tsx

@@ -0,0 +1,62 @@
+import { fireEvent, render, screen } from "@testing-library/react";
+import { createDemoRehearsalSong } from "@bandscope/shared-types";
+import { afterEach, describe, expect, it, vi } from "vitest";
+import { FirstHandoffCallout } from "./FirstHandoffCallout";
+
+function songWithHandoff() {
+  const song = createDemoRehearsalSong();
+  const verse = song.sections[0]!;
+  const handoff = structuredClone(verse);
+  handoff.id = "handoff-1";
+  handoff.label = "handoff";
+  handoff.timeRange = { start: 22, end: 24 };
+  handoff.roles = [
+    {
+      ...verse.roles[2]!,
+      id: "lead-vocal",
+      name: "Lead Vocal",
+      rehearsalPriority: "high"
+    }
+  ];
+  handoff.partGraph = [
+    {
+      role_id: "lead-vocal",
+      is_active: true,
+      handoff_to: [],
+      handoff_from: []
+    }
+  ];
+  song.sections = [verse, handoff];
+  return song;
+}
+
+describe("FirstHandoffCallout reduced motion", () => {
+  afterEach(() => {
+    vi.unstubAllGlobals();
+  });
+
+  it("scrolls immediately when the operating system requests reduced motion", () => {
+    const matchMedia = vi.fn().mockReturnValue({ matches: true });
+    vi.stubGlobal("matchMedia", matchMedia);
+
+    const grid = document.createElement("div");
+    grid.dataset.testid = "song-structure-grid";
+    const first = document.createElement("div");
+    const target = document.createElement("div");
+    const scrollIntoView = vi.fn();
+    Object.defineProperty(target, "scrollIntoView", {
+      configurable: true,
+      value: scrollIntoView
+    });
+    grid.appendChild(first);
+    grid.appendChild(target);
+    document.body.appendChild(grid);
+
+    render(<FirstHandoffCallout song={songWithHandoff()} />);
+    fireEvent.click(screen.getByRole("button", { name: "Open Lead Vocal handoff at 0:22" }));
+
+    expect(matchMedia).toHaveBeenCalledWith("(prefers-reduced-motion: reduce)");
+    expect(scrollIntoView).toHaveBeenCalledWith({ block: "nearest", behavior: "auto" });
+    grid.remove();
+  });
+});