diff --git a/front/src/query/query.tsx b/front/src/query/query.tsx
index 71d03c5bf..730692877 100644
--- a/front/src/query/query.tsx
+++ b/front/src/query/query.tsx
@@ -7,6 +7,7 @@ import {
 	useMutation as useRQMutation,
 } from "@tanstack/react-query";
 import { useCallback, useContext, useState } from "react";
+import { useTranslation } from "react-i18next";
 import { Platform } from "react-native";
 import type { z } from "zod/v4";
 import { type KyooError, type Page, Paged } from "~/models";
@@ -28,6 +29,7 @@ export const queryFn = async <Parser extends z.ZodTypeAny>(context: {
 	formData?: FormData;
 	plainText?: boolean;
 	authToken: string | null;
+	lang?: string;
 	parser: Parser | null;
 	signal?: AbortSignal;
 }): Promise<z.infer<Parser>> => {
@@ -47,6 +49,7 @@ export const queryFn = async <Parser extends z.ZodTypeAny>(context: {
 					? { Authorization: `Bearer ${context.authToken}` }
 					: {}),
 				...(context.body ? { "Content-Type": "application/json" } : {}),
+				"Accept-Language": context.lang ?? "en",
 			},
 			signal: context.signal,
 		});
@@ -170,6 +173,7 @@ export const keyToUrl = (key: ReturnType<typeof toQueryKey>) => {
 };
 
 export const useFetch = <Data,>(query: QueryIdentifier<Data>) => {
+	const { i18n } = useTranslation();
 	let { apiUrl, authToken, selectedAccount } = useContext(AccountContext);
 	if (query.options?.apiUrl) apiUrl = query.options.apiUrl;
 	const key = toQueryKey({ apiUrl, path: query.path, params: query.params });
@@ -182,6 +186,7 @@ export const useFetch = <Data,>(query: QueryIdentifier<Data>) => {
 				parser: query.parser,
 				signal: ctx.signal,
 				authToken: authToken ?? null,
+				lang: i18n.resolvedLanguage,
 				...query.options,
 			}) as Promise<Data>,
 		placeholderData: query.placeholderData as any,
@@ -230,6 +235,7 @@ export const useRefresh = (queries: QueryIdentifier<unknown>[]) => {
 };
 
 export const useInfiniteFetch = <Data,>(query: QueryIdentifier<Data>) => {
+	const { i18n } = useTranslation();
 	let { apiUrl, authToken } = useContext(AccountContext);
 	if (query.options?.apiUrl) apiUrl = query.options.apiUrl;
 	const key = toQueryKey({ apiUrl, path: query.path, params: query.params });
@@ -242,6 +248,7 @@ export const useInfiniteFetch = <Data,>(query: QueryIdentifier<Data>) => {
 				parser: query.parser ? Paged(query.parser) : null,
 				signal: ctx.signal,
 				authToken: authToken ?? null,
+				lang: i18n.resolvedLanguage,
 				...query.options,
 			}) as Promise<Page<Data>>,
 		getNextPageParam: (page: Page<Data>) => page?.next || undefined,
@@ -331,6 +338,7 @@ export const useMutation = <Ret = unknown, T = void, QueryRet = void>({
 	optimisticKey?: QueryIdentifier<unknown>;
 	invalidate: string[] | null;
 }) => {
+	const { i18n } = useTranslation();
 	const { apiUrl, authToken } = useContext(AccountContext);
 	const queryClient = useQueryClient();
 	const mutation = useRQMutation({
@@ -346,6 +354,7 @@ export const useMutation = <Ret = unknown, T = void, QueryRet = void>({
 				body,
 				formData,
 				authToken,
+				lang: i18n.resolvedLanguage,
 				parser: parser ?? null,
 			});
 		},
diff --git a/front/src/ui/player/controls/skip-chapter.tsx b/front/src/ui/player/controls/skip-chapter.tsx
index a316f075f..b5e414f0c 100644
--- a/front/src/ui/player/controls/skip-chapter.tsx
+++ b/front/src/ui/player/controls/skip-chapter.tsx
@@ -2,7 +2,7 @@ import { useCallback, useEffect, useRef, useState } from "react";
 import { useTranslation } from "react-i18next";
 import { useEvent, type VideoPlayer } from "react-native-video";
 import type { Chapter } from "~/models";
-import { Button } from "~/primitives";
+import { Button, P } from "~/primitives";
 import { useAccount } from "~/providers/account-context";
 import { useFetch } from "~/query";
 import { Info } from "~/ui/info";
@@ -76,12 +76,20 @@ export const SkipChapterButton = ({
 
 	return (
 		<Button
-			text={t(`player.chapters.skip`, { type: chapter.type })}
 			onPress={skipChapter}
 			className={cn(
 				"absolute right-safe bottom-2/10 m-8",
 				"z-20 bg-slate-900/70 px-4 py-2",
 			)}
-		/>
+		>
+			<P
+				className={cn(
+					"text-center text-slate-300 dark:text-slate-300",
+					"group-focus-within:text-slate-200 group-hover:text-slate-200",
+				)}
+			>
+				{t(`player.chapters.skip`, { type: chapter.type })}
+			</P>
+		</Button>
 	);
 };
diff --git a/front/src/ui/settings/general.tsx b/front/src/ui/settings/general.tsx
index 11228a942..f7967182a 100644
--- a/front/src/ui/settings/general.tsx
+++ b/front/src/ui/settings/general.tsx
@@ -2,6 +2,7 @@ import Theme from "@material-symbols/svg-400/outlined/dark_mode.svg";
 import Language from "@material-symbols/svg-400/outlined/language.svg";
 import Android from "@material-symbols/svg-400/rounded/android.svg";
 import Public from "@material-symbols/svg-400/rounded/public.svg";
+import { useQueryClient } from "@tanstack/react-query";
 import { useTranslation } from "react-i18next";
 import { Uniwind, useUniwind } from "uniwind";
 import { Link, Select } from "~/primitives";
@@ -11,6 +12,7 @@ import { Preference, SettingsContainer } from "./base";
 
 export const GeneralSettings = () => {
 	const { t, i18n } = useTranslation();
+	const queryClient = useQueryClient();
 	const theme = useUniwind();
 	const getLanguageName = useLanguageName();
 
@@ -41,7 +43,10 @@ export const GeneralSettings = () => {
 				<Select
 					label={t("settings.general.language.label")}
 					value={i18n.resolvedLanguage!}
-					onValueChange={(value) => i18n.changeLanguage(value)}
+					onValueChange={(value) => {
+						i18n.changeLanguage(value);
+						queryClient.invalidateQueries();
+					}}
 					values={supportedLanguages}
 					getLabel={(key) => getLanguageName(key) ?? key}
 				/>
diff --git a/transcoder/src/stream.go b/transcoder/src/stream.go
index c6c1f820b..96bde706a 100644
--- a/transcoder/src/stream.go
+++ b/transcoder/src/stream.go
@@ -344,6 +344,13 @@ func (ts *Stream) run(ctx context.Context, start int32) error {
 				cmd.Process.Signal(os.Interrupt)
 				slog.InfoContext(ctx, "killing ffmpeg because segment already ready", "segment", segment, "encoderId", encoder_id)
 				should_stop = true
+			} else if copy_audio && end < length && segment == end-1 {
+				// Extra overlap segment for copied audio.
+				// Delete the file immediately and stop without closing
+				// the channel, so a real producer can close it later.
+				extraPath := fmt.Sprintf(ts.handle.getOutPath(encoder_id), segment)
+				_ = os.Remove(extraPath)
+				should_stop = true
 			} else {
 				ts.segments[segment].encoder = encoder_id
 				close(ts.segments[segment].channel)
diff --git a/transcoder/tests/hls_validation/README.md b/transcoder/tests/hls_validation/README.md
index 1787d0c0f..539117f67 100644
--- a/transcoder/tests/hls_validation/README.md
+++ b/transcoder/tests/hls_validation/README.md
@@ -43,7 +43,7 @@ For `docker-compose.dev.yml` with API key auth via Traefik:
 
 ```bash
 TRANSCODER_BASE_URL="http://localhost:8901/video" \
-TRANSCODER_MEDIA_PATH="/video/Akudama Drive S01E01.mkv" \
+TRANSCODER_MEDIA_PATH="/video/The legend of korra S04E05.mkv" \
 TRANSCODER_API_KEY="admin" \
 uv run --with pytest pytest transcoder/tests/hls_validation -q
 ```
diff --git a/transcoder/tests/hls_validation/conftest.py b/transcoder/tests/hls_validation/conftest.py
index 48ea0a6f1..362320092 100644
--- a/transcoder/tests/hls_validation/conftest.py
+++ b/transcoder/tests/hls_validation/conftest.py
@@ -37,9 +37,12 @@ def test_config() -> TestConfig:
         )
 
     api_key = os.getenv("TRANSCODER_API_KEY", "").strip()
+    auth_token = os.getenv("TRANSCODER_AUTH_TOKEN", "").strip()
     headers: dict[str, str] = {}
     if api_key:
         headers["X-Api-Key"] = api_key
+    if auth_token:
+        headers["Authorization"] = f"Bearer {auth_token}"
 
     return TestConfig(
         base_url=os.getenv(
diff --git a/transcoder/tests/hls_validation/test_audio_copy_continuity.py b/transcoder/tests/hls_validation/test_audio_copy_continuity.py
new file mode 100644
index 000000000..e2ba1d4ef
--- /dev/null
+++ b/transcoder/tests/hls_validation/test_audio_copy_continuity.py
@@ -0,0 +1,105 @@
+from __future__ import annotations
+
+from .hls_utils import fetch_text, parse_media_playlist, probe_segment_timeline
+
+
+def test_copied_audio_has_no_gaps_at_lazy_window_boundaries(
+    master_context: dict, test_config, byte_cache
+) -> None:
+    """For -c:a copy, each lazy window (every ~100 segments) can drop a
+    boundary-crossing packet. Verify there are no audible gaps."""
+    max_allowed_gap_seconds = 0.06
+    failures: list[str] = []
+
+    for audio in master_context["audios"]:
+        # Only test the "original" (copied) audio rendition.
+        if "original" not in audio.url:
+            continue
+
+        text = fetch_text(
+            audio.url,
+            timeout_seconds=test_config.timeout_seconds,
+            headers=test_config.headers,
+        )
+        playlist = parse_media_playlist(text, audio.url, master_context["client_id"])
+        if len(playlist.segment_urls) < 102:
+            # Not enough segments to cross a boundary
+            continue
+
+        # Probe segments around each 100-segment boundary.
+        boundaries = [i for i in range(99, len(playlist.segment_urls), 100)]
+        for boundary in boundaries:
+            before = probe_segment_timeline(
+                segment_url=playlist.segment_urls[boundary],
+                map_url=playlist.map_url,
+                timeout_seconds=test_config.timeout_seconds,
+                byte_cache=byte_cache,
+                headers=test_config.headers,
+            )
+            after = probe_segment_timeline(
+                segment_url=playlist.segment_urls[boundary + 1],
+                map_url=playlist.map_url,
+                timeout_seconds=test_config.timeout_seconds,
+                byte_cache=byte_cache,
+                headers=test_config.headers,
+            )
+            gap = after.start - before.end
+            if gap > max_allowed_gap_seconds:
+                failures.append(
+                    f"{audio.attrs.get('GROUP-ID', audio.url)}"
+                    f" boundary={boundary}->{boundary + 1}"
+                    f" gap={gap:.6f}s"
+                )
+
+    assert not failures, "copied audio gap at lazy window boundary: " + ", ".join(
+        failures
+    )
+
+
+def test_copied_audio_has_no_large_gaps_anywhere(
+    master_context: dict, test_config, byte_cache
+) -> None:
+    """Check every consecutive segment pair in the copied audio for gaps."""
+    max_allowed_gap_seconds = 0.06
+    failures: list[str] = []
+
+    for audio in master_context["audios"]:
+        if "original" not in audio.url:
+            continue
+
+        text = fetch_text(
+            audio.url,
+            timeout_seconds=test_config.timeout_seconds,
+            headers=test_config.headers,
+        )
+        playlist = parse_media_playlist(text, audio.url, master_context["client_id"])
+        if len(playlist.segment_urls) < 2:
+            continue
+
+        # Check up to 50 consecutive pairs (enough to cross a window boundary).
+        sample_count = min(len(playlist.segment_urls) - 1, 50)
+        for idx in range(sample_count):
+            before = probe_segment_timeline(
+                segment_url=playlist.segment_urls[idx],
+                map_url=playlist.map_url,
+                timeout_seconds=test_config.timeout_seconds,
+                byte_cache=byte_cache,
+                headers=test_config.headers,
+            )
+            after = probe_segment_timeline(
+                segment_url=playlist.segment_urls[idx + 1],
+                map_url=playlist.map_url,
+                timeout_seconds=test_config.timeout_seconds,
+                byte_cache=byte_cache,
+                headers=test_config.headers,
+            )
+            gap = after.start - before.end
+            if gap > max_allowed_gap_seconds:
+                failures.append(
+                    f"{audio.attrs.get('GROUP-ID', audio.url)}"
+                    f" seg={idx}->{idx + 1} gap={gap:.6f}s"
+                )
+                # Fail fast on the first large gap
+                break
+
+    assert not failures, "copied audio gap detected: " + ", ".join(failures)