fix(core,studio): a voice track is never a carve bed, and never carves its own group

A narration clip inside a Voiceover group had a carve pointed at that
group — a member ducking the bus it feeds. Three faults, each sufficient
on its own.

**No bed-eligibility rule.** `couldBeCarveSource` has said since it was
written that music and sfx cannot be sources, and it is called from
nowhere — exported, tested, dead. Nothing ever asked the near-end
question: can this track be the BED. `showCarve` only asked "is anything
already carving against me, and is there anything to listen to", so a
voice track was offered the control like any other. Added
`couldBeCarveBed` beside its sibling and wired it in.

**Offering is not applying.** A bed with exactly one candidate carves
itself unasked, which is right for a track named `music-bed` and wrong
for one named `a1` — a decision taken off a name that said nothing is how
a carve appears that nobody remembers configuring. `isNamedCarveBed`
gates self-application on a name that positively reads as a bed; the
picker stays looser, the same split the source side already makes between
`sourceOptions` and `autoSourceIds`.

**A bed was offered its own group.** The candidate scan excluded exactly
one element, the bed itself. Its siblings survived that filter and rolled
up into the very group the bed belongs to, which came back as a
candidate — and being the only one, was applied. The mirror case too: a
group bed's id matches no <audio> id, so nothing stopped a group carving
against itself. `collectCarveCandidates` now takes the bed's id and drops
both it and its group.

An existing carve still shows its module (`carve !== null`), so nothing
already configured becomes unreachable — only newly offered and
self-applied ones are refused.

The bed/relationship predicates moved to `useFxCarveGrouping.ts`, next to
the source-eligibility rules they belong with. That is also what puts
`useFxCarve.ts` back under the 600-line ceiling it crossed here.

Five tests, each mutation-checked against the pre-fix code. Verified live:
selecting `vo-2` renders no carve module; `music-bed` still gets one,
listening to `Voiceover (4)`.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

packages/core/src/audioCarve.test.ts

@@ -10,6 +10,8 @@ import {
   clipsOverlap,
   mixCarveSources,
   couldBeCarveSource,
+  couldBeCarveBed,
+  isNamedCarveBed,
   DEFAULT_CARVE,
   normalizeCarveSettings,
 } from "./audioCarve.js";
@@ -538,6 +540,30 @@ describe("classifyAudioName", () => {
     expect(couldBeCarveSource("sfx-explosion")).toBe(false);
   });
 
+  // The near-end rule, which nothing used to ask. `couldBeCarveSource` shipped
+  // with its own doc comment ("music and sfx are out") and no caller; the bed
+  // side had no predicate at all, so a narration clip was offered the carve and
+  // — finding one candidate — had one applied for it, against the group it was
+  // a member of.
+  it("never offers a voice track as the bed, but keeps an unnamed one eligible", () => {
+    expect(couldBeCarveBed("music-bed")).toBe(true);
+    expect(couldBeCarveBed("sfx-riser")).toBe(true);
+    expect(couldBeCarveBed("a1")).toBe(true);
+    expect(couldBeCarveBed("vo-2")).toBe(false);
+    expect(couldBeCarveBed("voiceover")).toBe(false);
+    expect(couldBeCarveBed("narration-3")).toBe(false);
+  });
+
+  // Showing the control is a suggestion; writing the attribute is a decision.
+  // A decision taken off a name that said nothing is how a carve appears that
+  // nobody remembers configuring — so `a1` may be offered but never chosen.
+  it("only self-applies to a name that positively reads as a bed", () => {
+    expect(isNamedCarveBed("music-bed")).toBe(true);
+    expect(isNamedCarveBed("sfx-riser")).toBe(true);
+    expect(isNamedCarveBed("a1")).toBe(false);
+    expect(isNamedCarveBed("vo-2")).toBe(false);
+  });
+
   it("treats underscores as separators, not word characters, for short hints", () => {
     // `\b` treats `_` as a word character, so `\bbed\b` used to miss `bed_01` —
     // an underscore-separated bed classified as "unknown" and could end up

packages/core/src/audioCarve.ts

@@ -188,6 +188,40 @@ export function couldBeCarveSource(...parts: readonly (string | null | undefined
   return kind === "voice" || kind === "unknown";
 }
 
+/**
+ * Could this track be the BED a carve is written onto?
+ *
+ * The other half of `couldBeCarveSource`, and the half nothing used to ask. A
+ * carve makes room in a bed for a voice; a voice track has no room to make for
+ * itself, and offering it the control is offering a track to duck against its
+ * own kind. Observed: a narration clip in a Voiceover group carved against that
+ * group — a member ducking the bus it feeds.
+ *
+ * Loose in the same direction as its sibling: a name that says nothing stays
+ * eligible, because a name is a hint and an author may know better. Only a name
+ * that positively reads as speech is refused.
+ */
+export function couldBeCarveBed(...parts: readonly (string | null | undefined)[]): boolean {
+  return classifyAudioName(...parts) !== "voice";
+}
+
+/**
+ * Does this track's name positively say "bed"?
+ *
+ * Stricter than `couldBeCarveBed`, for the one act the author did not ask for:
+ * applying a carve on their behalf. Offering the control on a track named `a1`
+ * is a suggestion they can ignore; writing `data-fx-carve` onto it is a decision,
+ * and a decision taken off a name that said nothing is how a carve appears that
+ * nobody remembers configuring.
+ *
+ * The same split the source side already makes between what the picker may show
+ * and what `autoSourceIds` may choose unprompted.
+ */
+export function isNamedCarveBed(...parts: readonly (string | null | undefined)[]): boolean {
+  const kind = classifyAudioName(...parts);
+  return kind === "music" || kind === "sfx";
+}
+
 export const DEFAULT_CARVE: HfCarveSettings = {
   enabled: true,
   sources: [],

packages/studio/src/components/editor/propertyPanelAudioFxGroup.test.tsx

@@ -1341,6 +1341,62 @@ describe("AudioFxGroup carve by default", () => {
     expect(onSetAttributeQuiet.mock.calls.some((c) => c[0] === "data-fx-carve")).toBe(false);
     expect(host.querySelector(".hf-fx-carve-module")).toBeNull();
   });
+
+  /**
+   * Mount a track of the test's own naming as the selection, with siblings.
+   *
+   * `mount` always calls the selected track `bed`, which is what let the near-end
+   * hole go unnoticed: nothing ever selected a track whose NAME said voice.
+   */
+  const mountNamed = (id: string, siblings: string[]) => {
+    const onSetAttributeQuiet = vi.fn();
+    const selected = document.createElement("audio");
+    selected.id = id;
+    document.body.append(selected);
+    for (const other of siblings) {
+      const el = document.createElement("audio");
+      el.id = other;
+      document.body.append(el);
+    }
+    const host = document.createElement("div");
+    document.body.append(host);
+    act(() => {
+      createRoot(host).render(
+        <AudioFxGroup
+          element={
+            {
+              dataAttributes: { "fx-chain": "" },
+              id,
+              element: selected,
+            } as unknown as DomEditSelection
+          }
+          onSetAttributeQuiet={onSetAttributeQuiet}
+          onSetAttributeLive={vi.fn()}
+        />,
+      );
+    });
+    return { host, onSetAttributeQuiet };
+  };
+
+  // The reported bug. A carve makes room in a bed for a voice, so a voice track
+  // is the one thing that can never be the bed — `couldBeCarveSource` has said
+  // as much since it was written, and nothing called it. Selecting a narration
+  // clip offered it the module, found one candidate, and applied a carve nobody
+  // asked for.
+  it("never offers the carve on a track whose name says voice", () => {
+    const { host, onSetAttributeQuiet } = mountNamed("vo-2", ["music-bed"]);
+    expect(onSetAttributeQuiet.mock.calls.some((c) => c[0] === "data-fx-carve")).toBe(false);
+    expect(host.querySelector(".hf-fx-carve-module")).toBeNull();
+  });
+
+  // Offering is a suggestion, applying is a decision. An unnamed track keeps the
+  // module — the author may know better than the name does — but nothing is
+  // written until they say so.
+  it("offers but does not apply on a track whose name says nothing", () => {
+    const { host, onSetAttributeQuiet } = mountNamed("a1", ["vo-1"]);
+    expect(host.querySelector(".hf-fx-carve-module")).not.toBeNull();
+    expect(onSetAttributeQuiet.mock.calls.some((c) => c[0] === "data-fx-carve")).toBe(false);
+  });
 });
 
 describe("AudioFxGroup carve source list", () => {

packages/studio/src/components/editor/useFxCarve.ts

@@ -26,11 +26,12 @@ import {
   DEFAULT_CARVE,
   mixCarveSources,
   HF_AUDIO_CARVE_ATTR,
-  normalizeCarveSettings,
   type HfCarveSettings,
 } from "@hyperframes/core/audio-carve";
 import { resolveAudioGroups, resolveCarveSourceIds } from "@hyperframes/core/audio-groups";
 import {
+  carveBedRoles,
+  carverAgainst,
   collectCarveCandidates,
   CARVE_ABORTED,
   isPromiseLike,
@@ -54,17 +55,6 @@ import type { AudioTrackOption } from "./propertyPanelFxCarveModule.js";
  */
 const DECODE_SAMPLE_RATE = 48000;
 
-/** Whether some element's own carve attribute names `targetId` as a source. */
-function carvesAgainst(other: HTMLElement, targetId: string): boolean {
-  try {
-    const raw = other.getAttribute(HF_AUDIO_CARVE_ATTR);
-    return Boolean(raw && normalizeCarveSettings(JSON.parse(raw)).sources.includes(targetId));
-  } catch {
-    // An unreadable carve on some other element says nothing about this one.
-    return false;
-  }
-}
-
 /**
  * Which carve setting actually moved, by comparing the two snapshots.
  *
@@ -304,24 +294,10 @@ export function useFxCarve(
    */
   onAutoGroupCarveSources?: (clipIds: readonly string[], groupId: string) => Promise<void>,
 ) {
-  /**
-   * Is some other track carving against this one?
-   *
-   * A carve is a relationship — a bed is carved against a voice — and the voice is
-   * the far end of it. Offering the same control there offers to carve a track
-   * against itself by proxy, and switching it on left a setting with no source it
-   * could legally name. Read off the other elements' own carve attributes, because
-   * that is where the relationship is recorded.
-   */
-  const carvedAgainstBy = ((): string | null => {
-    const doc = element.element?.ownerDocument;
-    if (!doc || !element.id) return null;
-    const others = Array.from(doc.querySelectorAll<HTMLElement>(`[${HF_AUDIO_CARVE_ATTR}]`));
-    const carver = others.find(
-      (other) => other.id !== element.id && carvesAgainst(other, element.id ?? ""),
-    );
-    return carver ? carver.id || "another track" : null;
-  })();
+  const carvedAgainstBy = carverAgainst(element.element?.ownerDocument, element.id);
+
+  // Can this be a bed at all, and may one be applied unasked. See carveBedRoles.
+  const { couldBeBed, autoBed } = carveBedRoles(element.id, element.element);
 
   /**
    * The tracks worth offering as the voice.
@@ -336,13 +312,17 @@ export function useFxCarve(
    * safe direction: a name that says nothing stays in, voice-shaped names sort
    * first, and if filtering would leave nothing at all every track comes back. A
    * picker that hides the track somebody needs is worse than a long one.
+   *
+   * Empty on a track that cannot be a bed at all, which is what withholds the
+   * whole module: `showCarve` already asks "is there anything to carve against",
+   * so the near-end rule rides that rather than a second flag to thread.
    */
   const { sourceOptions, autoSourceIds } = ((): {
     sourceOptions: AudioTrackOption[];
     autoSourceIds: string[];
   } => {
     const doc = element.element?.ownerDocument;
-    if (!doc) return { sourceOptions: [], autoSourceIds: [] };
+    if (!doc || !couldBeBed) return { sourceOptions: [], autoSourceIds: [] };
     const others = Array.from(doc.querySelectorAll<HTMLAudioElement>("audio[id]")).filter(
       (a) => a.id !== element.id,
     );
@@ -353,7 +333,7 @@ export function useFxCarve(
     const overlapsBed = (a: Element): boolean =>
       clipsOverlap(bedSpan, spanOf(a.getAttribute("data-start"), a.getAttribute("data-duration")));
 
-    const described = collectCarveCandidates(doc, others, overlapsBed);
+    const described = collectCarveCandidates(doc, others, overlapsBed, element.id ?? undefined);
     const plausible = described.filter((t) => t.kind === "voice" || t.kind === "unknown");
     const offered = plausible.length > 0 ? plausible : described;
     const byVoiceFirst = (list: typeof described) =>
@@ -543,7 +523,7 @@ export function useFxCarve(
     // both guards passing for a single candidate fired two setCarve calls with
     // the same result — two decodes, two FFT runs, two concurrent attribute
     // writes.
-    if (carvedAgainstBy || autoSourceIds.length <= 1) return;
+    if (carvedAgainstBy || !autoBed || autoSourceIds.length <= 1) return;
     const all = autoSourceIds;
     // Nothing configured: the default carve, pointed at everything it could hear.
     if (carve === null) {
@@ -557,7 +537,7 @@ export function useFxCarve(
     // Keyed on the identity of the decision, not on setCarve — which is rebuilt
     // every render and would re-fire this.
     // eslint-disable-next-line react-hooks/exhaustive-deps
-  }, [carve, carvedAgainstBy, candidateIds]);
+  }, [carve, carvedAgainstBy, autoBed, candidateIds]);
 
   /**
    * A bed with one obvious voice above it carves itself.
@@ -578,7 +558,7 @@ export function useFxCarve(
    * reason the flag exists rather than "off" being an absent attribute.
    */
   useEffect(() => {
-    if (carvedAgainstBy || autoSourceIds.length !== 1) return;
+    if (carvedAgainstBy || !autoBed || autoSourceIds.length !== 1) return;
     const only = autoSourceIds[0];
     if (!only) return;
     // Nothing configured: the default carve, pointed at the one candidate.
@@ -594,7 +574,7 @@ export function useFxCarve(
     // Deliberately keyed on the identity of the decision, not on setCarve — which
     // is rebuilt every render and would re-fire this.
     // eslint-disable-next-line react-hooks/exhaustive-deps
-  }, [carve, carvedAgainstBy, autoSourceIds.length, autoSourceIds[0]]);
+  }, [carve, carvedAgainstBy, autoBed, autoSourceIds.length, autoSourceIds[0]]);
 
   return { carvedAgainstBy, sourceOptions, setCarve };
 }

packages/studio/src/components/editor/useFxCarveGrouping.test.ts

@@ -0,0 +1,55 @@
+// @vitest-environment happy-dom
+import { describe, expect, it } from "vitest";
+import { collectCarveCandidates } from "./useFxCarveGrouping";
+
+function previewDoc(html: string): Document {
+  const doc = document.implementation.createHTMLDocument("preview");
+  doc.body.innerHTML = html;
+  return doc;
+}
+
+/** What the panel would offer as sources for `bedId`, the way useFxCarve asks. */
+function candidatesFor(doc: Document, bedId: string) {
+  const others = Array.from(doc.querySelectorAll<HTMLAudioElement>("audio[id]")).filter(
+    (a) => a.id !== bedId,
+  );
+  return collectCarveCandidates(doc, others, () => true, bedId).map((c) => c.id);
+}
+
+const GROUPED_VOICES = `
+  <hf-audio-group id="voiceover" data-label="Voiceover"></hf-audio-group>
+  <audio id="vo-1" data-audio-group="voiceover"></audio>
+  <audio id="vo-2" data-audio-group="voiceover"></audio>
+  <audio id="music-bed"></audio>
+`;
+
+describe("collectCarveCandidates", () => {
+  // The observed bug: selecting vo-2 offered "Voiceover (2)" — the group vo-2 is
+  // itself a member of. The caller filters out the bed element, but vo-1 survives
+  // that filter and rolls up into exactly that group. Being the only candidate, it
+  // was then applied without the author asking: a member ducking the bus it feeds.
+  it("never offers a member the group it belongs to", () => {
+    expect(candidatesFor(previewDoc(GROUPED_VOICES), "vo-2")).toEqual(["music-bed"]);
+  });
+
+  // And the mirror: a group bed's own id matches no <audio> id, so nothing
+  // excluded it. Its members rolled up and handed the group back to itself.
+  it("never offers a group itself", () => {
+    const doc = previewDoc(GROUPED_VOICES);
+    expect(candidatesFor(doc, "voiceover")).toEqual(["music-bed"]);
+  });
+
+  it("still offers a group the bed has nothing to do with", () => {
+    const doc = previewDoc(`
+      ${GROUPED_VOICES}
+      <hf-audio-group id="sfx" data-label="SFX"></hf-audio-group>
+      <audio id="sfx-click" data-audio-group="sfx"></audio>
+    `);
+    expect(candidatesFor(doc, "music-bed")).toEqual(["voiceover", "sfx"]);
+  });
+
+  it("leaves an ungrouped bed's candidates alone", () => {
+    const doc = previewDoc(`<audio id="music-bed"></audio><audio id="vo-1"></audio>`);
+    expect(candidatesFor(doc, "music-bed")).toEqual(["vo-1"]);
+  });
+});

packages/studio/src/components/editor/useFxCarveGrouping.ts

@@ -7,7 +7,14 @@
  * `propertyPanelAudioFxGroup.tsx`.
  */
 
-import { classifyAudioName, type HfCarveSettings } from "@hyperframes/core/audio-carve";
+import {
+  classifyAudioName,
+  HF_AUDIO_CARVE_ATTR,
+  normalizeCarveSettings,
+  couldBeCarveBed,
+  isNamedCarveBed,
+  type HfCarveSettings,
+} from "@hyperframes/core/audio-carve";
 import { resolveAudioGroups } from "@hyperframes/core/audio-groups";
 
 /**
@@ -101,18 +108,38 @@ export interface CarveCandidate {
  * the whole timeline is relevant even if each of its segments only overlaps
  * part of the bed). Grouped members never appear individually.
  */
+/**
+ * The ids a carve may never name, for a bed of this id.
+ *
+ * A carve names what the bed ducks UNDER, so the bed can never be on that
+ * list — directly or through the bus it plays into. The caller filters the bed
+ * element out of `others`, but that only removes the bed itself: its siblings
+ * survive and roll up into the very group the bed is a member of, which came
+ * back as a candidate and, being the only one, was applied unprompted. And a
+ * group bed's own id never matches any <audio> id at all, so nothing stopped a
+ * group carving against itself.
+ */
+function excludedFor(groupByMember: Map<string, { id: string }>, bedId?: string): Set<string> {
+  const selfGroupId = bedId ? groupByMember.get(bedId)?.id : undefined;
+  return new Set([bedId, selfGroupId].filter((id): id is string => !!id));
+}
+
 export function collectCarveCandidates(
   doc: Document,
   others: readonly HTMLAudioElement[],
   overlapsBed: (a: Element) => boolean,
+  /** The bed's own id, so neither it nor the group it belongs to is offered. */
+  bedId?: string,
 ): CarveCandidate[] {
   const groupByMember = new Map(
     resolveAudioGroups(doc).flatMap((group) => group.memberIds.map((id) => [id, group] as const)),
   );
+  const excluded = excludedFor(groupByMember, bedId);
   const offeredGroupIds = new Set<string>();
   const described: CarveCandidate[] = [];
   for (const a of others) {
     const group = groupByMember.get(a.id);
+    if (excluded.has(a.id) || (group && excluded.has(group.id))) continue;
     if (!group) {
       if (overlapsBed(a)) {
         described.push({
@@ -144,3 +171,61 @@ export function collectCarveCandidates(
   }
   return described;
 }
+
+/**
+ * The two near-end questions about a track, asked of its name.
+ *
+ * `couldBeBed` — may a carve be written onto this at all? A carve makes room in
+ * a bed for a voice, so a voice track is the one thing that can never be the
+ * bed. The far-end rule (`couldBeCarveSource` — music and sfx are out) has
+ * existed since it was written and had no caller; this is the half nothing
+ * asked, and without it a narration clip was offered the control and, finding
+ * exactly one candidate, had a carve applied against the group it belonged to.
+ *
+ * `autoBed` — may one be applied WITHOUT the author asking? Stricter. Showing
+ * the module on a track named `a1` is a suggestion; writing `data-fx-carve`
+ * onto it is a decision, and a decision taken off a name that said nothing is
+ * how a carve turns up that nobody remembers configuring. The same split the
+ * source side already makes between what the picker may show (`sourceOptions`)
+ * and what it may choose unprompted (`autoSourceIds`).
+ *
+ * Reads the element's `data-label` as well as its id and `src`: a group carries
+ * its name there rather than in a filename, and a group can be a bed.
+ */
+export function carveBedRoles(
+  id: string | null | undefined,
+  node: Element | null | undefined,
+): { couldBeBed: boolean; autoBed: boolean } {
+  const parts = [id, node?.getAttribute("src"), node?.getAttribute("data-label")];
+  return { couldBeBed: couldBeCarveBed(...parts), autoBed: isNamedCarveBed(...parts) };
+}
+
+/** Whether some element's own carve attribute names `targetId` as a source. */
+function carvesAgainst(other: HTMLElement, targetId: string): boolean {
+  try {
+    const raw = other.getAttribute(HF_AUDIO_CARVE_ATTR);
+    return Boolean(raw && normalizeCarveSettings(JSON.parse(raw)).sources.includes(targetId));
+  } catch {
+    // An unreadable carve on some other element says nothing about this one.
+    return false;
+  }
+}
+
+/**
+ * Is some other track carving against this one, and which?
+ *
+ * A carve is a relationship — a bed is carved against a voice — and the voice is
+ * the far end of it. Offering the same control there offers to carve a track
+ * against itself by proxy, and switching it on left a setting with no source it
+ * could legally name. Read off the other elements' own carve attributes, because
+ * that is where the relationship is recorded.
+ */
+export function carverAgainst(
+  doc: Document | undefined,
+  id: string | null | undefined,
+): string | null {
+  if (!doc || !id) return null;
+  const others = Array.from(doc.querySelectorAll<HTMLElement>(`[${HF_AUDIO_CARVE_ATTR}]`));
+  const carver = others.find((other) => other.id !== id && carvesAgainst(other, id));
+  return carver ? carver.id || "another track" : null;
+}