feat(workspace): guide tonight's first intro 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 intro with the holding part when an active role is corroborated, the labeled start, 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 intro must name the holding part when corroborated, the labeled start, and the time so the next action is obvious.
 
 ## Security source
 

CHANGELOG.md

@@ -6,6 +6,7 @@
 
 - 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.
+- Name tonight's first labeled intro on the workspace and player so the room can count in together; 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.
 - 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.
 
 ### Changed

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 intro so the room can count in together; 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 +1,144 @@
+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 songWithIntro() {
+  const song = createDemoRehearsalSong();
+  const verse = song.sections[0]!;
+  const intro = structuredClone(verse);
+  intro.id = "intro-1";
+  intro.label = "intro";
+  intro.timeRange = { start: 0, end: 8 };
+  intro.roles = [
+    {
+      ...verse.roles[0]!,
+      id: "drums",
+      name: "Drums",
+      rehearsalPriority: "high"
+    }
+  ];
+  intro.partGraph = [
+    {
+      role_id: "drums",
+      is_active: true,
+      handoff_to: [],
+      handoff_from: []
+    }
+  ];
+  song.sections = [intro, verse];
+  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 intro from this player.")
+    ).toBeTruthy();
+  });
+
+  it("keeps the intro hear action unavailable without a player playback callback", () => {
+    render(<PlayerFeature title="Player" song={songWithIntro()} />);
+
+    expect(screen.queryByRole("button", { name: "Hear Drums start at 0:00" })).toBeNull();
+    expect(screen.getByText("Drums starts the intro at 0:00.")).toBeTruthy();
+  });
+
+  it("delegates the intro hear action to the owning player callback", () => {
+    const onPlayFromSeconds = vi.fn();
+    render(<PlayerFeature title="Player" song={songWithIntro()} onPlayFromSeconds={onPlayFromSeconds} />);
+
+    fireEvent.click(screen.getByRole("button", { name: "Hear Drums start at 0:00" }));
+
+    expect(onPlayFromSeconds).toHaveBeenCalledTimes(1);
+    expect(onPlayFromSeconds).toHaveBeenCalledWith(0);
+  });
+
+  it("localizes the section count, labels, and playback hint instead of mixing English player copy", () => {
+    vi.stubGlobal("navigator", { language: "ko-KR" });
+    try {
+      render(<PlayerFeature title="Player" song={songWithIntro()} />);
+      expect(screen.getByText("2개 구간")).toBeTruthy();
+      expect(screen.queryByText("2개 섹션")).toBeNull();
+      expect(screen.queryByText("2 sections")).toBeNull();
+      expect(screen.getByText("인트로")).toBeTruthy();
+      expect(screen.queryByText("intro")).toBeNull();
+      expect(screen.getByText("오디오 재생은 로컬 오디오 소스가 있는 데스크톱 앱에서 사용할 수 있습니다.")).toBeTruthy();
+      expect(screen.queryByText("Audio playback requires the desktop app with a local audio source.")).toBeNull();
+    } finally {
+      vi.unstubAllGlobals();
+    }
+  });
+
+  it("renders a safe empty summary when the runtime section collection is not an array", () => {
+    const song = songWithIntro();
+    (song as unknown as { sections: unknown }).sections = null;
+
+    render(<PlayerFeature title="Player" song={song} />);
+
+    expect(screen.getByText("No intro yet. Stay on tonight's map until the start is labeled.")).toBeTruthy();
+    expect(screen.getByText("0 sections")).toBeTruthy();
+  });
+
+  it("renders a safe empty summary when the runtime section collection is sparse", () => {
+    const song = songWithIntro();
+    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 intro yet. Stay on tonight's map until the start is labeled.")).toBeTruthy();
+    expect(screen.getByText("0 sections")).toBeTruthy();
+  });
+
+  it("renders a safe empty summary when sections is a throwing own accessor", () => {
+    const song = songWithIntro();
+    Object.defineProperty(song, "sections", {
+      configurable: true,
+      enumerable: true,
+      get() {
+        throw new Error("sections getter must stay data");
+      }
+    });
+
+    expect(() => render(<PlayerFeature title="Player" song={song} />)).not.toThrow();
+    expect(screen.getByText("No intro yet. Stay on tonight's map until the start is labeled.")).toBeTruthy();
+    expect(screen.getByText("0 sections")).toBeTruthy();
+  });
+
+  it("renders a safe empty summary when a song Proxy throws on sections access", () => {
+    const song = songWithIntro();
+    const proxiedSong = new Proxy(song, {
+      get(target, key, receiver) {
+        if (key === "sections") {
+          throw new Error("sections get trap");
+        }
+        return Reflect.get(target, key, receiver);
+      }
+    });
+
+    expect(() => render(<PlayerFeature title="Player" song={proxiedSong} />)).not.toThrow();
+    expect(screen.getByText("No intro yet. Stay on tonight's map until the start is labeled.")).toBeTruthy();
+    expect(screen.getByText("0 sections")).toBeTruthy();
+  });
+
+  it("omits malformed runtime section elements without crashing the player summary", () => {
+    const song = songWithIntro();
+    song.sections = [null, song.sections[1]!] 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 = songWithIntro();
+    (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

@@ -1,54 +1,131 @@
-import type { RehearsalSong } from "@bandscope/shared-types";
+import {
+  SECTION_FORM_LABELS,
+  type RehearsalSection,
+  type RehearsalSong,
+  type SectionFormLabel
+} from "@bandscope/shared-types";
+import { FirstIntroCallout } from "../workspace/FirstIntroCallout";
+import { createTranslator, detectPreferredLocale, translateSectionFormLabel } 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;
+};
+
+/** Read an own data property without invoking accessors or letting descriptor traps escape. */
+function readOwnDataProperty(value: object, key: PropertyKey): unknown {
+  try {
+    const descriptor = Object.getOwnPropertyDescriptor(value, key);
+    if (!descriptor || !("value" in descriptor)) {
+      return undefined;
+    }
+    Reflect.get(value, key);
+    return descriptor.value;
+  } catch {
+    return undefined;
+  }
+}
+
+/** 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 invoking an untrusted collection accessor. */
+function playerSummarySections(song: RehearsalSong): RehearsalSection[] {
+  const sections = readOwnDataProperty(song, "sections");
+  if (!Array.isArray(sections)) {
+    return [];
+  }
+  try {
+    const length = Number(sections.length);
+    if (!Number.isSafeInteger(length) || length < 0 || length > 0xffffffff) {
+      return [];
+    }
+    const keys = Object.keys(sections);
+    if (keys.length !== length || !keys.every((key, index) => key === String(index))) {
+      return [];
+    }
+    return sections.filter(isPlayerSummarySection);
+  } catch {
+    return [];
+  }
+}
+
+/** Player surface that names tonight's first labeled intro and delegates playback to the owning player. */
+export function PlayerFeature({ title, song, onPlayFromSeconds }: PlayerFeatureProps) {
+  const locale = detectPreferredLocale();
+  const t = createTranslator(locale);
 
   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("firstIntroNeedsSong")}</p>
       </section>
     );
   }
 
+  const sections = playerSummarySections(song);
+  const rawSongTitle = readOwnDataProperty(song, "title");
+  const songTitle = typeof rawSongTitle === "string" ? rawSongTitle : "";
+  const calloutSong = sections.length === 0
+    ? ({ sections: [] } as unknown as RehearsalSong)
+    : song;
+  const sectionCountLabel = t(
+    sections.length === 1
+      ? "metricConfidenceSectionCountSingular"
+      : "metricConfidenceSectionCountPlural"
+  ).replace("{count}", String(sections.length));
+
   return (
     <section style={{ padding: "24px" }}>
       <h2>{title}</h2>
+      <FirstIntroCallout song={calloutSong} actionMode="callback-only" onHearIntro={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"}
+            {sectionCountLabel}
           </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}
+              {translateSectionFormLabel(locale, section.label)}
             </span>
           ))}
         </div>
         <div style={{ marginTop: "16px", color: "#999", fontSize: "0.85em" }}>
-          Audio playback requires the desktop app with a local audio source.
+          {t("playerPlaybackRequiresDesktop")}
         </div>
       </div>
     </section>

apps/desktop/src/features/workspace/FirstIntroCallout.particle.test.tsx

@@ -0,0 +1,37 @@
+import { fireEvent, render, screen } from "@testing-library/react";
+import { createDemoRehearsalSong } from "@bandscope/shared-types";
+import { afterEach, describe, expect, it, vi } from "vitest";
+import { FirstIntroCallout } from "./FirstIntroCallout";
+
+describe("FirstIntroCallout Korean role copy", () => {
+  afterEach(() => {
+    vi.unstubAllGlobals();
+  });
+
+  it("keeps vowel-ending dynamic role names particle-safe before and after the intro action", () => {
+    vi.stubGlobal("navigator", { language: "ko-KR" });
+    const song = createDemoRehearsalSong();
+    const seed = song.sections[0]!;
+    const intro = structuredClone(seed);
+    intro.id = "intro-particle";
+    intro.label = "intro";
+    intro.timeRange = { start: 0, end: 8 };
+    intro.roles = [{ ...seed.roles[0]!, id: "piano", name: "피아노", rehearsalPriority: "high" }];
+    intro.partGraph = [
+      { role_id: "piano", is_active: true, handoff_to: [], handoff_from: [] }
+    ];
+    song.sections = [intro];
+
+    const onHearIntro = vi.fn();
+    render(<FirstIntroCallout song={song} actionMode="callback-only" onHearIntro={onHearIntro} />);
+
+    expect(screen.getByText("0:00 인트로에서 피아노 파트가 시작합니다.")).toBeTruthy();
+    expect(screen.queryByText(/피아노이/)).toBeNull();
+
+    fireEvent.click(screen.getByRole("button", { name: "0:00에 피아노 시작 듣기" }));
+
+    expect(onHearIntro).toHaveBeenCalledWith(0);
+    expect(screen.getByText("0:00에서 피아노 파트와 함께 카운트인하세요. 같이 시작하세요.")).toBeTruthy();
+    expect(screen.queryByText(/피아노과/)).toBeNull();
+  });
+});