chore: prepare av-tools 0.3.0 release

feat: make media inspection progressive
2026-07-27 18:38:20 +02:00 · 2026-07-27 18:25:47 +02:00
42 changed files with 2218 additions and 494 deletions
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,23 @@
 All notable changes to av-tools are documented here. The project follows
 semantic versioning once a first release is legally publishable.

+## 0.3.0 — 2026-07-27
+
+- Make imported media and browser-native duration/dimensions available without
+  loading FFmpeg, so recognized files can start playback immediately.
+- Move authoritative codec, stream, chapter and tag inspection to explicit or
+  operation-driven demand; keep playback usable after inspection failure and
+  expose bounded retry controls.
+- Inspect automatically when Quick Convert, preview proxies, timeline renders
+  or advanced tools require authoritative details, while preserving
+  deterministic multi-file timeline order.
+- Recover Firefox probes with a fresh same-mode core, safe MT-to-ST fallback
+  and operation reservations that prevent concurrent mounts or preference
+  changes.
+- Add Chromium and Firefox evidence proving the supplied 153 MB, 43-minute
+  lecture plays before detailed inspection and retains the same media element
+  afterward.
+
 ## 0.2.1 — 2026-07-27

 - Move the canonical source, manifest schema links, and package registry from
--- a/README.md
+++ b/README.md
@@ -8,8 +8,8 @@ telemetry, runtime CDN, remote-media fetch or third-party script.
 It is also a Toolbox SDK application. The same static build runs directly or
 under Toolbox Portal with shared shell, theme, help and app switching.

-> **Release status:** 0.2.1 is licensed GPL-3.0-or-later. Its canonical
-> release consists of the exact reviewed `v0.2.1` source, production
+> **Release status:** 0.3.0 is licensed GPL-3.0-or-later. Its canonical
+> release consists of the exact reviewed `v0.3.0` source, production
 > ZIP/checksum and Corresponding Source bundle published together. See
 > [Licensing](#licensing).

@@ -17,13 +17,13 @@ under Toolbox Portal with shared shell, theme, help and app switching.

 Two workflows keep the product intentionally smaller than a nonlinear editor:

- **Quick Convert:** drop/import media, inspect streams, choose a
-  capability-checked preset/streams, convert, preview when the browser can, and
-  download.
+- **Quick Convert:** drop/import media, play it and read browser-native file
+  information immediately, then inspect streams on demand when an export needs
+  authoritative details.
 - **Edit:** a media bin and sequential non-overlapping clip timeline with
  non-destructive settings, one export at a time.

-The 0.2 release covers typed/capability-gated conversion and remux,
+The 0.3 release covers typed/capability-gated conversion and remux,
 fast/accurate trim, split, compatible/normalized concatenate, reorder, crop,
 resize, frame-rate change, audio extraction/stream removal, waveform,
 peak/two-pass loudness normalization, gain, audio/video fades, metadata,
@@ -225,10 +225,12 @@ profile.

 `AV_TOOLS_LARGE_MEDIA=/absolute/video.mp4 npm run evidence:large-preview`
 performs the opt-in large-file regression: the native video element must mount
-and advance before bounded inspection finishes, remain the same element after
-the authoritative probe completes and produce no browser error.
+and advance while detailed inspection remains idle, browser-native
+duration/dimensions must appear without loading FFmpeg, and the same element
+must survive a subsequently requested authoritative probe. The command runs
+that evidence in both Chromium and Firefox.

-The latest recorded local Vitest run on 2026-07-26 completed **313 passing
+The latest recorded local Vitest run on 2026-07-27 completed **332 passing
 tests and two conditional skips**. It includes broad structured-command
 execution against native FFmpeg 7.1.3; the skipped native subtitle burn-in and
 labeled contact-sheet cases require `subtitles` and `drawtext` filters that are
@@ -241,9 +243,11 @@ queue and recovery workflows. The MT core is directly initialized and queried,
 and completes a real non-empty, re-probeable H.264/AAC conversion; the same
 path is benchmarked with 2-second 160×90 and 6-second 640×360 inputs. Nested
 static/Toolbox-context loading is also covered. This evidence is
-Chromium-specific: Firefox, Safari, mobile and exhaustive MT operation parity
-remain unrecorded. The exact one-run performance record and its limitations are
-in [performance observations](docs/PERFORMANCE.md).
+Chromium-specific. Firefox now covers the opt-in large-file
+play-before-inspection regression and its explicit authoritative-probe
+transition; broad Firefox operation parity, Safari, mobile and exhaustive MT
+operation parity remain unrecorded. The exact one-run performance record and
+its limitations are in [performance observations](docs/PERFORMANCE.md).

 ## Deployment

--- a/SOURCE.md
+++ b/SOURCE.md
@@ -1,6 +1,6 @@
 # Source and reproducibility record

-This file identifies the source corresponding to av-tools 0.2.1. It is not a
+This file identifies the source corresponding to av-tools 0.3.0. It is not a
 substitute for satisfying a component's licence or for delivering complete
 Corresponding Source with an object-code release.

@@ -9,9 +9,9 @@ Corresponding Source with an object-code release.
 - Canonical repository:
  `git@git.add-ideas.de:lotobo/av-tools.git`
 - Browser source: `https://git.add-ideas.de/lotobo/av-tools`
- Version: `0.2.1`
- Release source identity: immutable annotated tag `v0.2.1`
-  (`refs/tags/v0.2.1`) in the canonical repository.
+- Version: `0.3.0`
+- Release source identity: immutable annotated tag `v0.3.0`
+  (`refs/tags/v0.3.0`) in the canonical repository.
 - Application licence: `GPL-3.0-or-later`; full GPL version 3 terms in
  `LICENSE`.
 - Copyright: Copyright © 2026 Albrecht Degering.
@@ -22,10 +22,10 @@ the tag exists, is annotated, points to the reviewed release commit and is
 available without authentication:

 ```sh
-test "$(git cat-file -t v0.2.1)" = tag
-git rev-parse v0.2.1^{commit}
+test "$(git cat-file -t v0.3.0)" = tag
+git rev-parse v0.3.0^{commit}
 git ls-remote --tags \
-  https://git.add-ideas.de/lotobo/av-tools.git refs/tags/v0.2.1
+  https://git.add-ideas.de/lotobo/av-tools.git refs/tags/v0.3.0
 ```

 The Toolbox manifest names the canonical repository and SPDX licence. Publish
--- a/THIRD_PARTY_NOTICES.md
+++ b/THIRD_PARTY_NOTICES.md
@@ -1,6 +1,6 @@
 # Third-party notices

-av-tools 0.2.1 is Copyright © 2026 Albrecht Degering and licensed
+av-tools 0.3.0 is Copyright © 2026 Albrecht Degering and licensed
 GPL-3.0-or-later; see the root `LICENSE`. This inventory describes third-party
 inputs. It is informational, not legal advice, and does not replace their
 terms. Files under `LICENSES/` reproduce available terms. A packaged ZIP also
--- a/docs/ARCHITECTURE.md
+++ b/docs/ARCHITECTURE.md
@@ -27,8 +27,10 @@ Browser storage boundary
 ```

 - `src/toolbox/` owns the one typed manifest and suite integration.
- `src/media/` normalizes ffprobe JSON, duration/timecode, stream selection,
-  playback MIME decisions and safe names.
+- `src/media/` reads lightweight browser-native metadata, normalizes
+  authoritative ffprobe JSON, and owns duration/timecode, stream-selection,
+  playback-MIME and safe-name decisions. Browser metadata and probe data are
+  deliberately separate models.
 - `src/project/` owns the versioned, non-destructive project document and
  migrations. A source is represented by identity/metadata and must be
  reattached after load; the current application does not persist source bytes.
@@ -51,20 +53,35 @@ raw command field.

 ## FFmpeg lifecycle

-1. Inspect secure-context, worker, `crossOriginIsolated` and
+1. Import creates an object URL immediately. A detached native media element
+   reads duration/dimensions where supported; playback and file identity do not
+   initialize FFmpeg.
+2. Detailed inspection remains idle until the user requests it or an operation
+   requires codecs, complete streams, chapters, tags or dispositions.
+3. Inspect secure-context, worker, `crossOriginIsolated` and
   `SharedArrayBuffer` availability.
-2. Select MT only when all MT prerequisites are true (or ST when explicitly
+4. Select MT only when all MT prerequisites are true (or ST when explicitly
   selected). A failed MT load is terminated and retried once with ST.
-3. Load wrapper/core assets via base-relative, same-origin URLs.
-4. Query version/build configuration/formats/codecs/encoders/filters
+5. Load wrapper/core assets via base-relative, same-origin URLs.
+6. Query version/build configuration/formats/codecs/encoders/filters
   sequentially and publish immutable capability state.
-5. For one job, validate resource estimates and structured settings, allocate
+7. For one job, validate resource estimates and structured settings, allocate
   a generated directory, mount/write inputs, run a generated argument array,
   read only declared outputs, and re-probe applicable results.
-6. Return result bytes and an export report, then unmount/delete virtual files.
-7. Retain the idle engine for the next sequential job; terminate it on mode
+8. Return result bytes and an export report, then unmount/delete virtual files.
+9. Retain the idle engine for the next sequential job; terminate it on mode
   changes, unrecoverable errors or cancellation.

+A detailed-probe failure changes only the inspection state. The File, object
+URL, browser metadata and provisional timeline clip remain available, and the
+user can retry. An authoritative probe supersedes browser duration/dimensions
+and reconciles an untouched provisional full-source clip.
+
+The reviewed Emscripten runtime can stall when Firefox probes on a core that
+has retained prior application state. Before an explicit Firefox probe, the
+manager recreates the identical ST/MT core and reuses only that mode's already
+validated capability inventory. Chromium retains the normal warm-core path.
+
 The FFmpeg instance is a single process. `maxConcurrentFFmpegJobs` is one and
 no probe/export operations overlap on it. The application-facing scheduler is
 also bounded: it retains at most eight scheduled operations in memory,
--- a/docs/FORMAT_SUPPORT.md
+++ b/docs/FORMAT_SUPPORT.md
@@ -5,7 +5,7 @@ extensions or this document. The app queries muxers, demuxers, decoders,
 encoders and filters; a preset is disabled with missing components listed.
 Browser playback is a separate capability checked with MIME/media APIs.

-## 0.2.1 release fixture matrix
+## 0.3.0 release fixture matrix

 All 15 files are generated and re-probed with native FFmpeg 7.1.3 for test
 preparation and pass the checksum/probe verifier. That proves fixture
--- a/docs/KNOWN_LIMITATIONS.md
+++ b/docs/KNOWN_LIMITATIONS.md
@@ -1,6 +1,6 @@
 # Known limitations

-This is the conservative 0.2.1 release baseline. A capability appearing in
+This is the conservative 0.3.0 release baseline. A capability appearing in
 FFmpeg output does not remove these product/browser/resource limits.

 ## Functional
@@ -45,6 +45,9 @@ FFmpeg output does not remove these product/browser/resource limits.
  presets from runtime formats/codecs/encoders/filters.
 - FFmpeg-readable output may be download-only because browser media elements
  support fewer container/codec combinations.
+- Browser-native basic information intentionally omits codecs, complete stream
+  lists, chapters, tags, subtitles, attachments and dispositions. Features
+  that need those details request an authoritative local FFprobe pass.
 - Browser support, codec policy and memory differ across Chromium, Firefox and
  Safari and across desktop/mobile versions.
 - The reviewed 0.12.10 core profile passes the non-empty Opus encode/re-probe
@@ -79,13 +82,15 @@ FFmpeg output does not remove these product/browser/resource limits.
  verification against the live container.
 - The application is GPL-3.0-or-later and its native legal files and pinned
  source identities are included in the release record. Publish the production
-  ZIP/checksum, exact `v0.2.1` source and FFmpeg Corresponding Source bundle
+  ZIP/checksum, exact `v0.3.0` source and FFmpeg Corresponding Source bundle
  together; development-only smoke artifacts must not be distributed.
 - Chromium covers a broad real pinned-core ST operation matrix, a real MT
  H.264/AAC conversion, MT-to-ST fallback, nested static/Toolbox-context
-  loading and one two-size ST/MT performance baseline. Firefox, Safari, mobile,
-  exhaustive MT feature parity and repeated performance measurements remain
-  unrecorded. Live Portal container/header verification is a deployment gate.
+  loading and one two-size ST/MT performance baseline. Firefox covers the
+  opt-in large-file browser-metadata/playback-to-authoritative-probe
+  regression. Broad Firefox operation parity, Safari, mobile, exhaustive MT
+  feature parity and repeated performance measurements remain unrecorded. Live
+  Portal container/header verification is a deployment gate.

 See `docs/FORMAT_SUPPORT.md`, `docs/PERFORMANCE.md`,
 `docs/PORTAL_REQUIREMENTS.md` and `docs/RELEASE.md` for testable detail.
--- a/docs/PERFORMANCE.md
+++ b/docs/PERFORMANCE.md
@@ -80,11 +80,15 @@ frames meet the threshold. The documented ffmpeg.wasm input ceiling is 2 GiB,
 but real limits can be substantially lower on mobile or memory-constrained
 browsers.

-Source inspection has a bounded, size-aware watchdog: 30 seconds for small
-files, a two-MiB-per-second scan budget for larger files, and a five-minute
-ceiling. Recognized local audio/video can begin browser playback from its
-temporary object URL while that worker inspection continues; completed probe
-metadata remains authoritative for editing and export.
+Import does not start FFmpeg. Recognized local audio/video can begin browser
+playback from its temporary object URL while a native media element reads
+lightweight duration/dimensions. Detailed FFprobe inspection starts only when
+requested or required for an export and has a bounded, size-aware watchdog:
+30 seconds for small files, a two-MiB-per-second budget for larger files, and a
+five-minute ceiling. A detailed-inspection timeout is nonfatal; browser
+playback and basic file information remain available. Completed probe metadata
+remains authoritative for stream mapping, remux safety, chapters, tags,
+subtitles/attachments and export validation.

 Lowering resolution, duration, frame rate, passes and output count reduces
 work. MT can be faster but consumes more memory/CPU and requires isolation; ST
--- a/docs/RELEASE.md
+++ b/docs/RELEASE.md
@@ -11,7 +11,7 @@ The repository already declares the application licence and immutable
 third-party source identities. Before any distribution:

 1. commit the reviewed GPL-3.0-or-later source;
-2. create and verify annotated tag `v0.2.1` at that exact commit;
+2. create and verify annotated tag `v0.3.0` at that exact commit;
 3. push the commit and tag to the canonical public repository;
 4. assemble, review and publish corresponding source and exact external
   notices for both reviewed core profiles and linked libraries;
@@ -57,8 +57,8 @@ npm run package:release -- --allow-unlicensed-development-smoke
 Pass `--force` only to replace the exact same-version ZIP and sidecar. Output:

 ```text
-release/av-tools-0.2.1.zip
-release/av-tools-0.2.1.zip.sha256
+release/av-tools-0.3.0.zip
+release/av-tools-0.3.0.zip.sha256
 release/ffmpeg-core-0.12.10-reviewed-stack5m.1-corresponding-source.tar.xz
 release/ffmpeg-core-0.12.10-reviewed-stack5m.1-corresponding-source.tar.xz.sha256
 ```
@@ -68,7 +68,7 @@ Verify independently:
 ```sh
 node scripts/checksum-release.mjs
 (cd release && sha256sum -c ffmpeg-core-0.12.10-reviewed-stack5m.1-corresponding-source.tar.xz.sha256)
-unzip -l release/av-tools-0.2.1.zip
+unzip -l release/av-tools-0.3.0.zip
 tar -tJf release/ffmpeg-core-0.12.10-reviewed-stack5m.1-corresponding-source.tar.xz
 ```

@@ -96,7 +96,7 @@ exact `HEAD` and clones that revision into a temporary directory:

 ```sh
 npm run portal:smoke -- \
-  --artifact release/av-tools-0.2.1.zip \
+  --artifact release/av-tools-0.3.0.zip \
  --portal-root ../toolbox-portal
 ```

@@ -123,7 +123,7 @@ for `v0.6.0` and must not suppress review of new gaps. See

 ## 5. Publish only reviewed bytes

-From a clean `v0.2.1` checkout, rerun all checks, create the ZIP once, verify
+From a clean `v0.3.0` checkout, rerun all checks, create the ZIP once, verify
 the sidecar, assemble that exact ZIP through Portal, and publish the immutable
 ZIP, `.zip.sha256`, manifest, changelog, Corresponding Source and notices. Put
 its exact lowercase digest/version/id/target in a reviewed Portal lock. Never
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
  "name": "av-tools",
-  "version": "0.2.1",
+  "version": "0.3.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "av-tools",
-      "version": "0.2.1",
+      "version": "0.3.0",
      "license": "GPL-3.0-or-later",
      "dependencies": {
        "@add-ideas/toolbox-contract": "0.2.3",
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
  "name": "av-tools",
  "private": true,
-  "version": "0.2.1",
+  "version": "0.3.0",
  "description": "Local-first browser audio and video conversion and light editing with ffmpeg.wasm.",
  "license": "GPL-3.0-or-later",
  "author": "Albrecht Degering",
@@ -36,7 +36,7 @@
    "test": "vitest run",
    "test:watch": "vitest",
    "test:browser": "playwright test",
-    "evidence:large-preview": "playwright test tests/browser/large-media-preview.spec.ts --project=chromium --workers=1",
+    "evidence:large-preview": "playwright test tests/browser/large-media-preview.spec.ts --project=chromium --project=firefox-large-media --workers=1",
    "evidence:opus": "npm run vendor:ffmpeg && npm run vendor:verify-runtime && node scripts/opus-regression.mjs",
    "test:opus-regression": "npm run vendor:ffmpeg && npm run vendor:verify-runtime && node scripts/opus-regression.mjs --require-pass",
    "benchmark:browser": "AV_BENCHMARK=1 playwright test tests/browser/performance.spec.ts --project=chromium --workers=1",
--- a/playwright.config.ts
+++ b/playwright.config.ts
@@ -21,5 +21,10 @@ export default defineConfig({
      name: 'chromium',
      use: { ...devices['Desktop Chrome'] },
    },
+    {
+      name: 'firefox-large-media',
+      testMatch: 'large-media-preview.spec.ts',
+      use: { ...devices['Desktop Firefox'] },
+    },
  ],
 });
--- a/public/toolbox-app.json
+++ b/public/toolbox-app.json
@@ -3,7 +3,7 @@
  "schemaVersion": 1,
  "id": "de.add-ideas.av-tools",
  "name": "Audio & Video Tools",
-  "version": "0.2.1",
+  "version": "0.3.0",
  "description": "Convert and lightly edit audio and video locally in the browser.",
  "entry": "./",
  "icon": "./favicon.svg",
--- a/src/App.tsx
+++ b/src/App.tsx
--- a/src/app/application-state.ts
+++ b/src/app/application-state.ts
@@ -1,12 +1,21 @@
-import type { MediaProbe } from '../media';
+import type { BrowserMediaMetadata, MediaProbe } from '../media';

-export type AssetPhase = 'queued' | 'probing' | 'ready' | 'error';
+/**
+ * State of the optional authoritative FFprobe inspection.
+ *
+ * The File and its object URL are usable in every phase. In particular,
+ * `error` means only that detailed metadata is unavailable; it never marks the
+ * local source or browser playback as failed.
+ */
+export type AssetPhase = 'idle' | 'probing' | 'ready' | 'error';

 export interface ImportedMediaAsset {
  id: string;
  file: File;
  objectUrl: string;
  phase: AssetPhase;
+  browserMetadata?: BrowserMediaMetadata;
+  browserMetadataError?: string;
  probe?: MediaProbe;
  rawProbe?: string;
  error?: string;
@@ -29,10 +38,47 @@ export function createAsset(file: File): ImportedMediaAsset {
    id: crypto.randomUUID(),
    file,
    objectUrl: URL.createObjectURL(file),
-    phase: 'queued',
+    phase: 'idle',
  };
 }

+export function assetDurationSeconds(
+  asset: ImportedMediaAsset | undefined
+): number | undefined {
+  return (
+    asset?.probe?.durationSeconds ?? asset?.browserMetadata?.durationSeconds
+  );
+}
+
+export function assetHasVideo(
+  asset: ImportedMediaAsset | undefined
+): boolean | undefined {
+  if (asset?.probe) {
+    return asset.probe.streams.some(
+      (stream) =>
+        stream.type === 'video' && stream.disposition.attached_pic !== true
+    );
+  }
+  if (asset?.browserMetadata?.hasVideo !== undefined) {
+    return asset.browserMetadata.hasVideo;
+  }
+  if (asset?.browserMetadata?.kind === 'video') return true;
+  if (asset?.browserMetadata?.kind === 'audio') return false;
+  return undefined;
+}
+
+export function assetHasAudio(
+  asset: ImportedMediaAsset | undefined
+): boolean | undefined {
+  if (asset?.probe) {
+    return asset.probe.streams.some((stream) => stream.type === 'audio');
+  }
+  if (asset?.browserMetadata?.hasAudio !== undefined) {
+    return asset.browserMetadata.hasAudio;
+  }
+  return asset?.browserMetadata?.kind === 'audio' ? true : undefined;
+}
+
 export function formatBytes(bytes: number): string {
  if (!Number.isFinite(bytes) || bytes < 0) return 'Unknown size';
  if (bytes < 1_000) return `${bytes} B`;
--- a/src/components/CapabilityPanel.tsx
+++ b/src/components/CapabilityPanel.tsx
@@ -12,6 +12,7 @@ export interface CapabilityPanelProps {
  preference: EnginePreference;
  resourcePolicy: ResourcePolicy;
  deviceMemoryGiB?: number;
+  disabled?: boolean;
  onPreferenceChange: (preference: EnginePreference) => void;
  onInitialize: () => void;
 }
@@ -21,6 +22,7 @@ export function CapabilityPanel({
  preference,
  resourcePolicy,
  deviceMemoryGiB,
+  disabled = false,
  onPreferenceChange,
  onInitialize,
 }: CapabilityPanelProps) {
@@ -58,7 +60,12 @@ export function CapabilityPanel({
          Engine mode
          <select
            value={preference}
-            disabled={state.status === 'running'}
+            disabled={
+              disabled ||
+              state.status === 'loading' ||
+              state.status === 'recovering' ||
+              state.status === 'running'
+            }
            onChange={(event) =>
              onPreferenceChange(event.currentTarget.value as EnginePreference)
            }
@@ -188,7 +195,11 @@ export function CapabilityPanel({
          </p>
        </section>
        {state.status === 'idle' ? (
-          <button className="button button--secondary" onClick={onInitialize}>
+          <button
+            className="button button--secondary"
+            disabled={disabled}
+            onClick={onInitialize}
+          >
            Initialize engine
          </button>
        ) : null}
--- a/src/components/HelpDialog.tsx
+++ b/src/components/HelpDialog.tsx
@@ -60,10 +60,9 @@ export function HelpDialog({ open, onClose }: HelpDialogProps) {
            <span className="step-number">1</span>
            <h3>Add media</h3>
            <p>
-              Pick or drop local files. The browser gives FFmpeg direct,
-              read-only access when WORKERFS is available. If it must use the
-              bounded memory-copy fallback, the job log reports the exact copied
-              byte count.
+              Pick or drop local files. Playback, file identity, duration and
+              dimensions use the browser first; FFmpeg stays unloaded until
+              detailed streams or an export are requested.
            </p>
          </section>
          <section>
@@ -71,7 +70,8 @@ export function HelpDialog({ open, onClose }: HelpDialogProps) {
            <h3>Choose an operation</h3>
            <p>
              Quick Convert produces one output. Edit arranges non-destructive
-              clips on a sequential timeline.
+              clips on a sequential timeline. Detailed inspection adds codecs,
+              complete streams, chapters and tags only when needed.
            </p>
          </section>
          <section>
--- a/src/components/Inspector.tsx
+++ b/src/components/Inspector.tsx
@@ -1,6 +1,11 @@
 import { useState } from 'react';
 import type { ImportedMediaAsset } from '../app/application-state';
-import { formatBytes, formatDuration } from '../app/application-state';
+import {
+  assetDurationSeconds,
+  assetHasVideo,
+  formatBytes,
+  formatDuration,
+} from '../app/application-state';
 import type {
  AvProjectV1,
  FadeCurve,
@@ -39,6 +44,7 @@ export interface InspectorProps {
  onChaptersChange: (chapters: ProjectChapter[]) => void;
  onSubtitlesChange: (tracks: ProjectSubtitleTrack[]) => void;
  onSubtitleImport?: (file: File) => void;
+  onInspectDetails?: (assetId: string) => void;
  onThumbnail: (request: ThumbnailRequest) => void;
  currentPreviewTimeSeconds?: number;
  disabled?: boolean;
@@ -74,6 +80,7 @@ export function Inspector({
  onChaptersChange,
  onSubtitlesChange,
  onSubtitleImport,
+  onInspectDetails,
  onThumbnail,
  currentPreviewTimeSeconds,
  disabled = false,
@@ -119,7 +126,13 @@ export function Inspector({
        ))}
      </div>
      <div className="inspector__body">
-        {tab === 'media' ? <MediaInspector asset={asset} /> : null}
+        {tab === 'media' ? (
+          <MediaInspector
+            asset={asset}
+            disabled={disabled}
+            onInspectDetails={onInspectDetails}
+          />
+        ) : null}
        {tab === 'transform' ? (
          <TransformInspector
            clip={clip}
@@ -159,7 +172,7 @@ export function Inspector({
        ) : null}
        {tab === 'thumbnails' ? (
          <ThumbnailInspector
-            duration={asset?.probe?.durationSeconds}
+            duration={assetDurationSeconds(asset)}
            currentPreviewTimeSeconds={currentPreviewTimeSeconds}
            disabled={disabled || !asset}
            onCreate={onThumbnail}
@@ -170,20 +183,30 @@ export function Inspector({
  );
 }

-function MediaInspector({ asset }: { asset?: ImportedMediaAsset }) {
+function MediaInspector({
+  asset,
+  disabled,
+  onInspectDetails,
+}: {
+  asset?: ImportedMediaAsset;
+  disabled: boolean;
+  onInspectDetails?: (assetId: string) => void;
+}) {
  if (!asset) return <p className="panel-empty">Select a media source.</p>;
  const probe = asset.probe;
+  const durationSeconds = assetDurationSeconds(asset);
+  const hasVideo = assetHasVideo(asset) === true;
+  const width =
+    probe?.streams.find((stream) => stream.type === 'video')?.width ??
+    asset.browserMetadata?.width;
+  const height =
+    probe?.streams.find((stream) => stream.type === 'video')?.height ??
+    asset.browserMetadata?.height;
  return (
    <div className="inspector-section">
      <div className="inspector-file">
        <span>
-          <Icon
-            name={
-              probe?.streams.some((stream) => stream.type === 'video')
-                ? 'video'
-                : 'audio'
-            }
-          />
+          <Icon name={hasVideo ? 'video' : 'audio'} />
        </span>
        <div>
          <strong>{asset.file.name}</strong>
@@ -191,6 +214,18 @@ function MediaInspector({ asset }: { asset?: ImportedMediaAsset }) {
        </div>
      </div>
      <dl className="detail-list">
+        <div>
+          <dt>File type</dt>
+          <dd>
+            {asset.browserMetadata?.file.declaredMimeType &&
+            asset.browserMetadata.file.declaredMimeType !==
+              'application/octet-stream'
+              ? asset.browserMetadata.file.declaredMimeType
+              : (asset.browserMetadata?.file.inferredMimeType ??
+                asset.browserMetadata?.file.declaredMimeType ??
+                (asset.file.type || '—'))}
+          </dd>
+        </div>
        <div>
          <dt>Container</dt>
          <dd>
@@ -199,8 +234,21 @@ function MediaInspector({ asset }: { asset?: ImportedMediaAsset }) {
        </div>
        <div>
          <dt>Duration</dt>
-          <dd>{formatDuration(probe?.durationSeconds)}</dd>
+          <dd>
+            {formatDuration(durationSeconds)}
+            {!probe && durationSeconds !== undefined ? ' · browser' : ''}
+          </dd>
        </div>
+        {hasVideo ? (
+          <div>
+            <dt>Dimensions</dt>
+            <dd>
+              {width !== undefined && height !== undefined
+                ? `${width}×${height}${probe ? '' : ' · browser'}`
+                : '—'}
+            </dd>
+          </div>
+        ) : null}
        <div>
          <dt>Bit rate</dt>
          <dd>
@@ -210,6 +258,41 @@ function MediaInspector({ asset }: { asset?: ImportedMediaAsset }) {
          </dd>
        </div>
      </dl>
+      {!probe ? (
+        <div
+          className={`notice ${
+            asset.phase === 'error' ? 'notice--warning' : ''
+          }`}
+          role="status"
+        >
+          <Icon name={asset.phase === 'error' ? 'warning' : 'info'} />
+          <div>
+            <strong>
+              {asset.phase === 'probing'
+                ? 'Inspecting detailed media information…'
+                : asset.phase === 'error'
+                  ? 'Detailed inspection is unavailable.'
+                  : 'Detailed information has not been inspected.'}
+            </strong>
+            <small>
+              {asset.phase === 'error'
+                ? asset.error
+                : 'Codecs, complete streams, chapters and tags are loaded only when needed.'}
+            </small>
+          </div>
+          {asset.phase !== 'probing' && onInspectDetails ? (
+            <button
+              type="button"
+              className="button button--secondary"
+              disabled={disabled}
+              onClick={() => onInspectDetails(asset.id)}
+            >
+              <Icon name="info" />
+              {asset.phase === 'error' ? 'Retry inspection' : 'Inspect details'}
+            </button>
+          ) : null}
+        </div>
+      ) : null}
      {probe && Object.keys(probe.tags).length > 0 ? (
        <>
          <h3>Container tags</h3>
@@ -223,66 +306,69 @@ function MediaInspector({ asset }: { asset?: ImportedMediaAsset }) {
          </dl>
        </>
      ) : null}
-      <h3>Streams</h3>
-      <ol className="inspector-streams">
-        {probe?.streams.map((stream) => (
-          <li key={stream.index}>
-            <span className="stream-kind">{stream.type}</span>
-            <div>
-              <strong>
-                #{stream.index} · {stream.codecName ?? 'unknown'}
-              </strong>
-              {stream.type === 'video' ? (
-                <>
+      {probe ? <h3>Streams</h3> : null}
+      {probe ? (
+        <ol className="inspector-streams">
+          {probe?.streams.map((stream) => (
+            <li key={stream.index}>
+              <span className="stream-kind">{stream.type}</span>
+              <div>
+                <strong>
+                  #{stream.index} · {stream.codecName ?? 'unknown'}
+                </strong>
+                {stream.type === 'video' ? (
+                  <>
+                    <small>
+                      Encoded pixels {stream.width ?? '?'}×
+                      {stream.height ?? '?'}
+                      {stream.codedWidth !== undefined &&
+                      stream.codedHeight !== undefined
+                        ? ` · coded ${stream.codedWidth}×${stream.codedHeight}`
+                        : ''}
+                      {' · '}
+                      {stream.frameRate?.toFixed(3) ?? '?'} fps
+                    </small>
+                    <small>
+                      SAR {stream.sampleAspectRatio ?? '—'} · DAR{' '}
+                      {stream.displayAspectRatio ?? '—'} · rotation{' '}
+                      {stream.rotationDegrees === undefined
+                        ? '—'
+                        : `${stream.rotationDegrees}°`}
+                    </small>
+                  </>
+                ) : (
                  <small>
-                    Encoded pixels {stream.width ?? '?'}×{stream.height ?? '?'}
-                    {stream.codedWidth !== undefined &&
-                    stream.codedHeight !== undefined
-                      ? ` · coded ${stream.codedWidth}×${stream.codedHeight}`
-                      : ''}
-                    {' · '}
-                    {stream.frameRate?.toFixed(3) ?? '?'} fps
+                    {stream.type === 'audio'
+                      ? `${stream.sampleRate ?? '?'} Hz · ${stream.channelLayout ?? `${stream.channels ?? '?'} channels`}`
+                      : (stream.language ??
+                        stream.title ??
+                        'No additional details')}
                  </small>
+                )}
+                {Object.keys(stream.disposition).length > 0 ? (
                  <small>
-                    SAR {stream.sampleAspectRatio ?? '—'} · DAR{' '}
-                    {stream.displayAspectRatio ?? '—'} · rotation{' '}
-                    {stream.rotationDegrees === undefined
-                      ? '—'
-                      : `${stream.rotationDegrees}°`}
+                    Disposition:{' '}
+                    {Object.entries(stream.disposition)
+                      .filter(([, enabled]) => enabled)
+                      .map(([name]) => name)
+                      .join(', ') || 'none'}
                  </small>
-                </>
-              ) : (
-                <small>
-                  {stream.type === 'audio'
-                    ? `${stream.sampleRate ?? '?'} Hz · ${stream.channelLayout ?? `${stream.channels ?? '?'} channels`}`
-                    : (stream.language ??
-                      stream.title ??
-                      'No additional details')}
-                </small>
-              )}
-              {Object.keys(stream.disposition).length > 0 ? (
-                <small>
-                  Disposition:{' '}
-                  {Object.entries(stream.disposition)
-                    .filter(([, enabled]) => enabled)
-                    .map(([name]) => name)
-                    .join(', ') || 'none'}
-                </small>
-              ) : null}
-              {Object.keys(stream.tags).length > 0 ? (
-                <dl className="stream-tag-list">
-                  {Object.entries(stream.tags).map(([key, value]) => (
-                    <div key={key}>
-                      <dt>{key}</dt>
-                      <dd>{value}</dd>
-                    </div>
-                  ))}
-                </dl>
-              ) : null}
-            </div>
-          </li>
-        )) ?? <li>Waiting for inspection.</li>}
-      </ol>
+                ) : null}
+                {Object.keys(stream.tags).length > 0 ? (
+                  <dl className="stream-tag-list">
+                    {Object.entries(stream.tags).map(([key, value]) => (
+                      <div key={key}>
+                        <dt>{key}</dt>
+                        <dd>{value}</dd>
+                      </div>
+                    ))}
+                  </dl>
+                ) : null}
+              </div>
+            </li>
+          ))}
+        </ol>
+      ) : null}
      {probe && probe.chapters.length > 0 ? (
        <>
          <h3>Source chapters</h3>
@@ -333,8 +419,8 @@ function TransformInspector({
 }) {
  if (!clip) return <p className="panel-empty">Select a timeline clip.</p>;
  const video = asset?.probe?.streams.find((stream) => stream.type === 'video');
-  const sourceWidth = video?.width;
-  const sourceHeight = video?.height;
+  const sourceWidth = video?.width ?? asset?.browserMetadata?.width;
+  const sourceHeight = video?.height ?? asset?.browserMetadata?.height;
  const canShowVisualCrop =
    asset !== undefined &&
    isPositiveSafeInteger(sourceWidth) &&
--- a/src/components/MediaBin.tsx
+++ b/src/components/MediaBin.tsx
@@ -1,11 +1,19 @@
 import type { ImportedMediaAsset } from '../app/application-state';
-import { formatBytes, formatDuration } from '../app/application-state';
+import {
+  assetDurationSeconds,
+  assetHasVideo,
+  formatBytes,
+  formatDuration,
+} from '../app/application-state';
 import { Icon } from './Icon';

 export interface MediaBinProps {
  assets: readonly ImportedMediaAsset[];
  selectedId?: string;
  onSelect: (id: string) => void;
+  onInspect: (id: string) => void;
+  inspectDisabled?: boolean;
+  removeDisabled?: boolean;
  onRemove: (id: string) => void;
 }

@@ -13,6 +21,9 @@ export function MediaBin({
  assets,
  selectedId,
  onSelect,
+  onInspect,
+  inspectDisabled = false,
+  removeDisabled = false,
  onRemove,
 }: MediaBinProps) {
  if (assets.length === 0) {
@@ -27,9 +38,13 @@ export function MediaBin({
  return (
    <ul className="media-list" aria-label="Imported media">
      {assets.map((asset) => {
+        const hasVideo = assetHasVideo(asset) === true;
        const video = asset.probe?.streams.find(
          (stream) => stream.type === 'video'
        );
+        const durationSeconds = assetDurationSeconds(asset);
+        const width = video?.width ?? asset.browserMetadata?.width;
+        const height = video?.height ?? asset.browserMetadata?.height;
        const audioCount =
          asset.probe?.streams.filter((stream) => stream.type === 'audio')
            .length ?? 0;
@@ -43,34 +58,67 @@ export function MediaBin({
              ]
                .filter(Boolean)
                .join(' ')}
+              aria-pressed={selectedId === asset.id}
              onClick={() => onSelect(asset.id)}
            >
              <span className="media-card__type">
-                <Icon name={video ? 'video' : 'audio'} />
+                <Icon name={hasVideo ? 'video' : 'audio'} />
              </span>
              <span className="media-card__content">
                <strong title={asset.file.name}>{asset.file.name}</strong>
                <small>
                  {formatBytes(asset.file.size)}
-                  {asset.probe?.durationSeconds !== undefined
-                    ? ` · ${formatDuration(asset.probe.durationSeconds)}`
+                  {durationSeconds !== undefined
+                    ? ` · ${formatDuration(durationSeconds)}`
                    : ''}
                </small>
                <small className={`phase phase--${asset.phase}`}>
                  {asset.phase === 'probing'
-                    ? 'Inspecting locally…'
+                    ? `${asset.browserMetadata ? 'Ready to play' : 'File ready'} · Inspecting details…`
                    : asset.phase === 'ready'
-                      ? `${video ? `${video.width ?? '?'}×${video.height ?? '?'}` : 'Audio'} · ${audioCount} audio`
+                      ? `${hasVideo ? `${width ?? '?'}×${height ?? '?'}` : 'Audio'} · ${audioCount} audio`
                      : asset.phase === 'error'
-                        ? asset.error
-                        : 'Queued'}
+                        ? `${asset.browserMetadata ? 'Ready to play' : 'File ready'} · Details unavailable`
+                        : asset.browserMetadataError
+                          ? 'File ready · Basic metadata unavailable'
+                          : asset.browserMetadata
+                            ? 'Ready to play · Details on demand'
+                            : 'File ready · Reading basic metadata…'}
                </small>
              </span>
            </button>
+            {asset.phase !== 'ready' ? (
+              <button
+                className="icon-action"
+                type="button"
+                aria-label={`${asset.phase === 'error' ? 'Retry detailed inspection for' : 'Inspect details for'} ${asset.file.name}`}
+                title={
+                  asset.phase === 'error'
+                    ? asset.error
+                    : 'Read codecs, streams, chapters and tags'
+                }
+                disabled={inspectDisabled || asset.phase === 'probing'}
+                {...(asset.error
+                  ? { 'aria-describedby': `inspection-error-${asset.id}` }
+                  : {})}
+                onClick={() => onInspect(asset.id)}
+              >
+                <Icon name={asset.phase === 'probing' ? 'queue' : 'info'} />
+              </button>
+            ) : null}
+            {asset.error ? (
+              <span
+                className="visually-hidden"
+                id={`inspection-error-${asset.id}`}
+              >
+                {asset.error}
+              </span>
+            ) : null}
            <button
              className="icon-action"
              type="button"
              aria-label={`Remove ${asset.file.name}`}
+              disabled={removeDisabled}
              onClick={() => onRemove(asset.id)}
            >
              <Icon name="trash" />
--- a/src/components/MediaPreview.tsx
+++ b/src/components/MediaPreview.tsx
@@ -1,5 +1,6 @@
 import { useEffect, useMemo, useRef, useState } from 'react';
 import type { ImportedMediaAsset } from '../app/application-state';
+import { assetHasAudio, assetHasVideo } from '../app/application-state';
 import {
  assessBrowserPlayback,
  assessGeneratedResultPreview,
@@ -60,18 +61,15 @@ export function MediaPreview({
        : undefined;
  const hasVideo = result
    ? result.mimeType.startsWith('video/')
-    : asset?.probe
-      ? asset.probe.streams.some(
-          (stream) =>
-            stream.type === 'video' && stream.disposition.attached_pic !== true
-        )
+    : assetHasVideo(asset) !== undefined
+      ? assetHasVideo(asset) === true
      : declaredSourceMimeType
        ? isVideoMimeType(declaredSourceMimeType)
        : false;
  const hasAudio = result
    ? result.mimeType.startsWith('audio/')
-    : asset?.probe
-      ? asset.probe.streams.some((stream) => stream.type === 'audio')
+    : assetHasAudio(asset) !== undefined
+      ? assetHasAudio(asset) === true
      : declaredSourceMimeType
        ? isAudioMimeType(declaredSourceMimeType)
        : false;
@@ -207,8 +205,10 @@ export function MediaPreview({
              : `Generated result · ${result.name}`
            : (playback?.reason ??
              (asset?.phase === 'probing'
-                ? 'Local source preview · Media inspection continues in the background.'
-                : 'Local source preview'))}
+                ? 'Local source preview · Detailed inspection runs separately.'
+                : asset?.phase === 'error'
+                  ? 'Local source preview · Detailed inspection unavailable.'
+                  : 'Local source preview · Basic browser metadata'))}
        </span>
        {needsProxy && !proxySettings ? (
          <button type="button" className="text-button" onClick={onCreateProxy}>
--- a/src/components/QuickConvert.tsx
+++ b/src/components/QuickConvert.tsx
@@ -1,7 +1,7 @@
 import { useMemo, useState } from 'react';
 import type { ImportedMediaAsset } from '../app/application-state';
+import { assetDurationSeconds, assetHasVideo } from '../app/application-state';
 import type { EngineState } from '../ffmpeg/ffmpeg.types';
-import type { MediaStreamProbe } from '../media';
 import type { StreamSelection } from '../commands/command-utils';
 import {
  validateRemuxCompatibility,
@@ -18,8 +18,12 @@ import {
 import { formatBytes, formatDuration } from '../app/application-state';
 import { FFMPEG_OPUS_REGRESSION_VERIFIED } from '../version';
 import { Icon } from './Icon';
+import {
+  quickStreamUnavailableReason,
+  type QuickOperation,
+} from './quick-convert-selection';

-export type QuickOperation = 'convert' | 'remux';
+export type { QuickOperation } from './quick-convert-selection';

 export interface QuickExportConfiguration {
  operation: QuickOperation;
@@ -28,6 +32,11 @@ export interface QuickExportConfiguration {
  streamSelection: StreamSelection;
  removeMetadata: boolean;
  removeChapters: boolean;
+  /**
+   * The source was not authoritatively inspected when the user submitted the
+   * form. Resolve a safe default selection from the on-demand probe.
+   */
+  selectDetectedStreams?: true;
 }

 export interface QuickConvertProps {
@@ -36,6 +45,7 @@ export interface QuickConvertProps {
  busy: boolean;
  queueing?: boolean;
  presets?: readonly ExportPreset[];
+  onInspect?: () => void;
  onExport: (configuration: QuickExportConfiguration) => void;
 }

@@ -45,6 +55,7 @@ export function QuickConvert({
  busy,
  queueing = false,
  presets = BUILT_IN_PRESETS,
+  onInspect,
  onExport,
 }: QuickConvertProps) {
  const [operation, setOperation] = useState<QuickOperation>('convert');
@@ -59,6 +70,7 @@ export function QuickConvert({
  }>();

  const preset = presets.find((entry) => entry.id === presetId);
+  const hasDetailedInformation = asset?.probe !== undefined;
  const streams = useMemo(() => asset?.probe?.streams ?? [], [asset?.probe]);
  const requestedStreams = useMemo(
    () =>
@@ -143,7 +155,9 @@ export function QuickConvert({
  const opusBlockedByPinnedCore =
    preset?.audio?.codec === 'libopus' && !FFMPEG_OPUS_REGRESSION_VERIFIED;
  const presetNeedsMissingAudio =
-    preset?.kind === 'audio' && effectiveSelection.audio.length === 0;
+    hasDetailedInformation &&
+    preset?.kind === 'audio' &&
+    effectiveSelection.audio.length === 0;
  const remuxStreams: readonly RemuxStream[] = streams.flatMap((stream) =>
    stream.type === 'video' ||
    stream.type === 'audio' ||
@@ -159,16 +173,17 @@ export function QuickConvert({
        ]
      : []
  );
-  const remuxDiagnostics = remuxContainer
-    ? validateRemuxCompatibility(
-        {
-          streams: remuxStreams,
-          hasChapters: Boolean(asset?.probe?.chapters.length),
-        },
-        remuxContainer,
-        effectiveSelection
-      )
-    : [];
+  const remuxDiagnostics =
+    remuxContainer && hasDetailedInformation
+      ? validateRemuxCompatibility(
+          {
+            streams: remuxStreams,
+            hasChapters: Boolean(asset?.probe?.chapters.length),
+          },
+          remuxContainer,
+          effectiveSelection
+        )
+      : [];
  const remuxErrors = remuxDiagnostics.filter(
    (diagnostic) => diagnostic.severity === 'error'
  );
@@ -179,9 +194,9 @@ export function QuickConvert({
  const remuxUnavailableReason = remuxMuxerMissing
    ? `The loaded core is missing muxer ${remuxContainer}.`
    : remuxErrors.map((diagnostic) => diagnostic.message).join(' ');
-  const hasSelectedStream = selectedStreams.size > 0;
+  const hasSelectedStream = !hasDetailedInformation || selectedStreams.size > 0;
  const canExport =
-    asset?.phase === 'ready' &&
+    asset !== undefined &&
    !busy &&
    hasSelectedStream &&
    (operation === 'remux'
@@ -228,27 +243,23 @@ export function QuickConvert({
      {asset ? (
        <div className="source-summary">
          <span className="source-summary__icon">
-            <Icon
-              name={
-                asset.probe?.streams.some((stream) => stream.type === 'video')
-                  ? 'video'
-                  : 'audio'
-              }
-            />
+            <Icon name={assetHasVideo(asset) === true ? 'video' : 'audio'} />
          </span>
          <div>
            <strong>{asset.file.name}</strong>
            <span>
              {formatBytes(asset.file.size)} ·{' '}
-              {formatDuration(asset.probe?.durationSeconds)}
+              {formatDuration(assetDurationSeconds(asset))}
            </span>
          </div>
          <span className={`phase phase--${asset.phase}`}>
            {asset.phase === 'ready'
-              ? 'Ready'
-              : asset.phase === 'error'
-                ? 'Could not inspect'
-                : 'Preparing'}
+              ? 'Details ready'
+              : asset.phase === 'probing'
+                ? 'Inspecting details'
+                : asset.phase === 'error'
+                  ? 'Ready to play'
+                  : 'Ready to play'}
          </span>
        </div>
      ) : (
@@ -340,14 +351,16 @@ export function QuickConvert({
                  ['ogg', 'Ogg (.ogg)'],
                ] as const
              ).map(([container, label]) => {
-                const diagnostics = validateRemuxCompatibility(
-                  {
-                    streams: remuxStreams,
-                    hasChapters: Boolean(asset?.probe?.chapters.length),
-                  },
-                  container,
-                  effectiveSelection
-                );
+                const diagnostics = hasDetailedInformation
+                  ? validateRemuxCompatibility(
+                      {
+                        streams: remuxStreams,
+                        hasChapters: Boolean(asset?.probe?.chapters.length),
+                      },
+                      container,
+                      effectiveSelection
+                    )
+                  : [];
                const missingMuxer =
                  engineState.status === 'ready' &&
                  !engineState.capabilities.muxers.has(container);
@@ -410,7 +423,25 @@ export function QuickConvert({
              );
            })
          ) : (
-            <p>Streams appear after local inspection.</p>
+            <div className="stream-picker__empty">
+              <p>
+                Streams will be identified only when you inspect details or
+                start this export.
+              </p>
+              {asset && asset.phase !== 'probing' && onInspect ? (
+                <button
+                  type="button"
+                  className="button button--secondary"
+                  disabled={busy}
+                  onClick={onInspect}
+                >
+                  <Icon name="info" />
+                  {asset.phase === 'error'
+                    ? 'Retry inspection'
+                    : 'Inspect details now'}
+                </button>
+              ) : null}
+            </div>
          )}
        </fieldset>

@@ -451,6 +482,13 @@ export function QuickConvert({
          Select at least one audio stream for an audio-only preset.
        </p>
      ) : null}
+      {asset?.phase === 'error' && !asset.probe ? (
+        <p className="notice notice--warning">
+          <Icon name="warning" />
+          Playback and basic file information remain available. Detailed
+          inspection can be retried when an export needs it.
+        </p>
+      ) : null}
      {!hasSelectedStream && streams.length > 0 ? (
        <p className="notice notice--error">
          <Icon name="warning" />
@@ -474,7 +512,11 @@ export function QuickConvert({
                ? 'Validated user preset'
                : 'Stream copy'}
          </strong>
-          <span>Resource estimates are checked before allocation.</span>
+          <span>
+            {hasDetailedInformation
+              ? 'Resource estimates are checked before allocation.'
+              : 'Detailed stream inspection will run before this export.'}
+          </span>
        </div>
        <button
          className="button button--primary button--large"
@@ -488,6 +530,9 @@ export function QuickConvert({
              streamSelection: effectiveSelection,
              removeMetadata,
              removeChapters,
+              ...(!hasDetailedInformation
+                ? { selectDetectedStreams: true as const }
+                : {}),
            })
          }
        >
@@ -497,47 +542,14 @@ export function QuickConvert({
            : queueing
              ? 'Add to queue'
              : operation === 'remux'
-                ? 'Remux'
-                : 'Convert'}
+                ? hasDetailedInformation
+                  ? 'Remux'
+                  : 'Inspect & remux'
+                : hasDetailedInformation
+                  ? 'Convert'
+                  : 'Inspect & convert'}
        </button>
      </footer>
    </section>
  );
 }
-
-function quickStreamUnavailableReason(
-  stream: MediaStreamProbe,
-  operation: QuickOperation,
-  preset: ExportPreset | undefined
-): string | undefined {
-  if (stream.type === 'unknown') {
-    return 'unknown stream kinds cannot be mapped safely.';
-  }
-  if (operation === 'remux') {
-    return undefined;
-  }
-  if (!preset) {
-    return 'choose an export preset first.';
-  }
-  if (stream.type === 'video' && !preset.video) {
-    return 'the selected preset creates audio only.';
-  }
-  if (stream.type === 'audio' && !preset.audio) {
-    return 'the selected preset creates video or images without audio.';
-  }
-  if (stream.type === 'subtitle') {
-    if (preset.subtitlePolicy === 'none') {
-      return 'the selected preset explicitly omits subtitles.';
-    }
-    if (preset.subtitlePolicy === 'burn-in') {
-      return 'burn-in requires an explicitly attached subtitle source.';
-    }
-  }
-  if (
-    (stream.type === 'attachment' || stream.type === 'data') &&
-    preset.container !== 'matroska'
-  ) {
-    return `${stream.type} streams are only preserved by the reviewed Matroska conversion path.`;
-  }
-  return undefined;
-}
--- a/src/components/quick-convert-selection.ts
+++ b/src/components/quick-convert-selection.ts
@@ -0,0 +1,70 @@
+import type { StreamSelection } from '../commands/command-utils';
+import type { MediaProbe, MediaStreamProbe } from '../media';
+import type { ExportPreset } from '../commands/convert';
+
+export type QuickOperation = 'convert' | 'remux';
+
+export function defaultQuickStreamSelection(
+  probe: MediaProbe,
+  operation: QuickOperation,
+  preset: ExportPreset | undefined
+): StreamSelection {
+  const selected = probe.streams.filter(
+    (stream) =>
+      quickStreamUnavailableReason(stream, operation, preset) === undefined
+  );
+  return {
+    video: selected
+      .filter((stream) => stream.type === 'video')
+      .map((stream) => stream.index),
+    audio: selected
+      .filter((stream) => stream.type === 'audio')
+      .map((stream) => stream.index),
+    subtitles: selected
+      .filter((stream) => stream.type === 'subtitle')
+      .map((stream) => stream.index),
+    attachments: selected
+      .filter((stream) => stream.type === 'attachment')
+      .map((stream) => stream.index),
+    data: selected
+      .filter((stream) => stream.type === 'data')
+      .map((stream) => stream.index),
+  };
+}
+
+export function quickStreamUnavailableReason(
+  stream: MediaStreamProbe,
+  operation: QuickOperation,
+  preset: ExportPreset | undefined
+): string | undefined {
+  if (stream.type === 'unknown') {
+    return 'unknown stream kinds cannot be mapped safely.';
+  }
+  if (operation === 'remux') {
+    return undefined;
+  }
+  if (!preset) {
+    return 'choose an export preset first.';
+  }
+  if (stream.type === 'video' && !preset.video) {
+    return 'the selected preset creates audio only.';
+  }
+  if (stream.type === 'audio' && !preset.audio) {
+    return 'the selected preset creates video or images without audio.';
+  }
+  if (stream.type === 'subtitle') {
+    if (preset.subtitlePolicy === 'none') {
+      return 'the selected preset explicitly omits subtitles.';
+    }
+    if (preset.subtitlePolicy === 'burn-in') {
+      return 'burn-in requires an explicitly attached subtitle source.';
+    }
+  }
+  if (
+    (stream.type === 'attachment' || stream.type === 'data') &&
+    preset.container !== 'matroska'
+  ) {
+    return `${stream.type} streams are only preserved by the reviewed Matroska conversion path.`;
+  }
+  return undefined;
+}
--- a/src/ffmpeg/EngineManager.ts
+++ b/src/ffmpeg/EngineManager.ts
@@ -23,7 +23,11 @@ import type {
 import { createLoadConfig } from './load-config';
 import { LogBuffer } from './log-buffer';
 import { normalizeProgress } from './progress-parser';
-import { describeMountedInputAccess, mountJobFiles } from './virtual-fs';
+import {
+  describeMountedInputAccess,
+  mountJobFiles,
+  type MountedJobFiles,
+} from './virtual-fs';
 import {
  parseFFmpegProgress,
  progressUpdateFromFFmpeg,
@@ -71,6 +75,25 @@ export function probeTimeoutMilliseconds(inputBytes: number): number {
  );
 }

+/**
+ * Firefox can leave this reviewed Emscripten core in a state where a later
+ * ffprobe call stalls after otherwise successful FFmpeg executions. A fresh
+ * worker/core completes the same probe promptly. Keep the workaround narrow
+ * so other browsers retain their warm-core startup path.
+ */
+export function shouldRefreshCoreBeforeProbe(userAgent?: string): boolean {
+  const resolvedUserAgent =
+    userAgent ?? (typeof navigator === 'undefined' ? '' : navigator.userAgent);
+  return /(?:^|\s)(?:Firefox|FxiOS)\//u.test(resolvedUserAgent);
+}
+
+export function canReuseProbeCapabilities(
+  loadedMode: EngineMode,
+  cachedMode: EngineMode
+): boolean {
+  return loadedMode === cachedMode;
+}
+
 async function defaultFFmpegFactory(): Promise<FFmpegAdapter> {
  const { FFmpeg } = await import('@ffmpeg/ffmpeg');
  return new FFmpeg();
@@ -98,6 +121,7 @@ export class EngineManager {
  #warning: Extract<EngineState, { status: 'ready' }>['warning'];
  #loadPromise: Promise<void> | null = null;
  #activeJobId: string | null = null;
+  #preparingOperation = false;
  #activeExpectedDurationSeconds: number | undefined;
  #activeStartedAtMilliseconds = 0;
  #machineProgressLines: string[] = [];
@@ -108,35 +132,40 @@ export class EngineManager {
  #generation = 0;

  readonly #handleLog = (event: LogEvent): void => {
+    // Capability discovery emits thousands of individual lines. Forwarding
+    // each one into React while the engine is still loading can starve
+    // Firefox's worker message queue long enough for the following probe to
+    // hit its watchdog. queryCapabilities installs its own short-lived
+    // listener, so application job logs only need to be retained/published
+    // while an operation is running.
+    if (this.#state.status !== 'running') return;
    this.#logs.append(event);
-    if (this.#state.status === 'running') {
-      for (const line of event.message.split(/\r?\n/gu)) {
-        if (/^(?:frame|fps|out_time_us|out_time|speed|progress)=/u.test(line)) {
-          this.#machineProgressLines.push(line);
-        }
-        if (/^progress=(?:continue|end)$/u.test(line)) {
-          const parsed = parseFFmpegProgress(
-            this.#machineProgressLines.join('\n')
-          );
-          const update = progressUpdateFromFFmpeg(
-            parsed,
-            this.#activeExpectedDurationSeconds
-          );
-          this.#machineProgressLines = [];
-          this.#machineProgressSeen = true;
-          this.#setState({
-            ...this.#state,
-            ...(update.progress !== undefined
-              ? { progress: update.progress }
-              : {}),
-            ...(update.speed !== undefined ? { speed: update.speed } : {}),
-            ...(update.frame !== undefined ? { frame: update.frame } : {}),
-            elapsedSeconds: Math.max(
-              0,
-              (performance.now() - this.#activeStartedAtMilliseconds) / 1_000
-            ),
-          });
-        }
+    for (const line of event.message.split(/\r?\n/gu)) {
+      if (/^(?:frame|fps|out_time_us|out_time|speed|progress)=/u.test(line)) {
+        this.#machineProgressLines.push(line);
+      }
+      if (/^progress=(?:continue|end)$/u.test(line)) {
+        const parsed = parseFFmpegProgress(
+          this.#machineProgressLines.join('\n')
+        );
+        const update = progressUpdateFromFFmpeg(
+          parsed,
+          this.#activeExpectedDurationSeconds
+        );
+        this.#machineProgressLines = [];
+        this.#machineProgressSeen = true;
+        this.#setState({
+          ...this.#state,
+          ...(update.progress !== undefined
+            ? { progress: update.progress }
+            : {}),
+          ...(update.speed !== undefined ? { speed: update.speed } : {}),
+          ...(update.frame !== undefined ? { frame: update.frame } : {}),
+          elapsedSeconds: Math.max(
+            0,
+            (performance.now() - this.#activeStartedAtMilliseconds) / 1_000
+          ),
+        });
      }
    }
    for (const listener of this.#logListeners) listener(event);
@@ -174,10 +203,16 @@ export class EngineManager {
  }

  setPreference(preference: EnginePreference): void {
-    if (this.#state.status === 'running') {
+    if (
+      this.#activeJobId ||
+      this.#preparingOperation ||
+      this.#state.status === 'loading' ||
+      this.#state.status === 'recovering' ||
+      this.#state.status === 'running'
+    ) {
      throw new EngineError(
        'busy',
-        'Engine mode cannot be changed while a job is running.'
+        'Engine mode cannot be changed while another operation is active.'
      );
    }
    if (preference !== this.#preference) {
@@ -203,7 +238,11 @@ export class EngineManager {
  }

  async initialize(): Promise<void> {
-    if (this.#activeJobId || this.#state.status === 'running') {
+    if (
+      this.#activeJobId ||
+      this.#preparingOperation ||
+      this.#state.status === 'running'
+    ) {
      throw new EngineError(
        'busy',
        'The FFmpeg engine cannot be initialized while another operation is active.'
@@ -290,7 +329,11 @@ export class EngineManager {

  async #loadMode(
    mode: EngineMode,
-    warning?: Extract<EngineState, { status: 'ready' }>['warning']
+    warning?: Extract<EngineState, { status: 'ready' }>['warning'],
+    cached?: {
+      readonly mode: EngineMode;
+      readonly capabilities: FFmpegCapabilities;
+    }
  ): Promise<void> {
    const generation = ++this.#generation;
    this.#setState({
@@ -317,9 +360,15 @@ export class EngineManager {
      status: 'loading',
      mode,
      progress: 0.75,
-      stage: 'Inspecting codec capabilities',
+      stage:
+        cached && canReuseProbeCapabilities(mode, cached.mode)
+          ? 'Restoring codec capabilities'
+          : 'Inspecting codec capabilities',
    });
-    const capabilities = await queryCapabilities(engine);
+    const capabilities =
+      cached && canReuseProbeCapabilities(mode, cached.mode)
+        ? cached.capabilities
+        : await queryCapabilities(engine);
    if (generation !== this.#generation) return;
    this.#capabilities = capabilities;
    this.#executionsSinceLoad = 0;
@@ -329,27 +378,54 @@ export class EngineManager {
  }

  async runJob(request: EngineJobRequest): Promise<EngineJobResult> {
-    if (this.#activeJobId) {
+    if (this.#activeJobId || this.#preparingOperation) {
      throw new EngineError(
        'busy',
        'Another FFmpeg operation is already running.'
      );
    }
    await this.initialize();
-    const coreWorkload = request.coreWorkload ?? request.operation;
-    await this.#recycleExecutionCoreIfNeeded(coreWorkload);
-    const engine = this.#engine;
-    const mode = this.#mode;
-    if (!engine || !mode || this.#state.status !== 'ready') {
-      throw new EngineError('load-failed', 'The FFmpeg engine is not ready.');
+    if (this.#activeJobId || this.#preparingOperation) {
+      throw new EngineError(
+        'busy',
+        'Another FFmpeg operation is already running.'
+      );
    }

-    const mounted = await mountJobFiles(
-      engine,
-      request.id,
-      request.inputs,
-      request.outputs.map(({ name }) => name)
-    );
+    let prepared:
+      | {
+          readonly engine: FFmpegAdapter;
+          readonly mode: EngineMode;
+          readonly mounted: MountedJobFiles;
+        }
+      | undefined;
+    const coreWorkload = request.coreWorkload ?? request.operation;
+    this.#preparingOperation = true;
+    try {
+      await this.#recycleExecutionCoreIfNeeded(coreWorkload, true);
+      const engine = this.#engine;
+      const mode = this.#mode;
+      if (!engine || !mode || this.#state.status !== 'ready') {
+        throw new EngineError('load-failed', 'The FFmpeg engine is not ready.');
+      }
+      const mounted = await mountJobFiles(
+        engine,
+        request.id,
+        request.inputs,
+        request.outputs.map(({ name }) => name)
+      );
+      this.#activeJobId = request.id;
+      prepared = { engine, mode, mounted };
+    } finally {
+      this.#preparingOperation = false;
+    }
+    if (!prepared) {
+      throw new EngineError(
+        'filesystem-failed',
+        'Could not prepare the FFmpeg job.'
+      );
+    }
+    const { engine, mode, mounted } = prepared;
    const generation = this.#generation;
    const temporaryPaths = (request.temporaryFiles ?? []).map(
      (temporary, index) => {
@@ -358,7 +434,6 @@ export class EngineManager {
        return `${mounted.workDirectory}/temporary-${index}.${extension}`;
      }
    );
-    this.#activeJobId = request.id;
    this.#activeExpectedDurationSeconds = request.expectedDurationSeconds;
    this.#activeStartedAtMilliseconds = performance.now();
    this.#machineProgressLines = [];
@@ -561,22 +636,79 @@ export class EngineManager {
      );
    }

-    const id = crypto.randomUUID();
-    const mounted = await mountJobFiles(engine, id, [file], ['probe.json']);
-    if (signal?.aborted) {
-      await mounted.cleanup();
-      throw new EngineError('cancelled', 'The media probe was cancelled.');
+    if (this.#activeJobId || this.#preparingOperation) {
+      throw new EngineError(
+        'busy',
+        'Another FFmpeg operation is already running.'
+      );
    }
+
+    let prepared:
+      | {
+          readonly engine: FFmpegAdapter;
+          readonly mode: EngineMode;
+          readonly mounted: MountedJobFiles;
+        }
+      | undefined;
+    this.#preparingOperation = true;
+    try {
+      await this.#refreshCoreBeforeProbe(signal);
+      if (signal?.aborted) {
+        throw new EngineError('cancelled', 'The media probe was cancelled.');
+      }
+      const refreshedEngine = this.#engine;
+      const refreshedMode = this.#mode;
+      if (
+        !refreshedEngine ||
+        !refreshedMode ||
+        this.#state.status !== 'ready'
+      ) {
+        throw new EngineError('load-failed', 'The FFmpeg engine is not ready.');
+      }
+      const id = crypto.randomUUID();
+      const mounted = await mountJobFiles(
+        refreshedEngine,
+        id,
+        [file],
+        ['probe.json']
+      );
+      if (signal?.aborted) {
+        await mounted.cleanup();
+        throw new EngineError('cancelled', 'The media probe was cancelled.');
+      }
+      this.#activeJobId = `probe-${id}`;
+      prepared = {
+        engine: refreshedEngine,
+        mode: refreshedMode,
+        mounted,
+      };
+    } finally {
+      this.#preparingOperation = false;
+    }
+    if (!prepared) {
+      throw new EngineError(
+        'filesystem-failed',
+        'Could not prepare the media probe.'
+      );
+    }
+    const { engine: refreshedEngine, mode: refreshedMode, mounted } = prepared;
    const probeOutput = mounted.outputPaths[0];
    const inputPath = mounted.inputPaths[0];
    if (!probeOutput || !inputPath) {
+      this.#activeJobId = null;
+      await mounted.cleanup();
      throw new EngineError(
        'filesystem-failed',
        'Could not allocate probe paths.'
      );
    }
-    const activeProbeId = `probe-${id}`;
-    this.#activeJobId = activeProbeId;
+    const activeProbeId = this.#activeJobId;
+    if (!activeProbeId) {
+      throw new EngineError(
+        'filesystem-failed',
+        'Could not reserve the media probe.'
+      );
+    }
    this.#activeExpectedDurationSeconds = undefined;
    this.#activeStartedAtMilliseconds = performance.now();
    this.#machineProgressLines = [];
@@ -584,7 +716,7 @@ export class EngineManager {
    this.#logs.clear();
    this.#setState({
      status: 'running',
-      mode,
+      mode: refreshedMode,
      jobId: this.#activeJobId,
      operation: 'Inspect media',
      inputMode: mounted.inputMode,
@@ -605,7 +737,7 @@ export class EngineManager {
    };
    signal?.addEventListener('abort', cancelOnAbort, { once: true });
    try {
-      const exitCode = await engine.ffprobe([
+      const exitCode = await refreshedEngine.ffprobe([
        '-v',
        'error',
        '-show_format',
@@ -620,7 +752,7 @@ export class EngineManager {
      let parsed: unknown;
      try {
        parsed = JSON.parse(
-          textFromFileData(await engine.readFile(probeOutput))
+          textFromFileData(await refreshedEngine.readFile(probeOutput))
        ) as unknown;
      } catch (readError) {
        throw new EngineError(
@@ -691,16 +823,19 @@ export class EngineManager {
      this.#activeJobId = null;
      this.#machineProgressLines = [];
      this.#machineProgressSeen = false;
-      if (this.#engine === engine) {
+      if (this.#engine === refreshedEngine) {
        const cleanupSucceeded = await mounted.cleanup();
-        if (!cleanupSucceeded && this.#engine === engine) {
+        if (!cleanupSucceeded && this.#engine === refreshedEngine) {
          this.#logs.append({
            type: 'stderr',
            message:
              'Probe filesystem cleanup could not be verified; recreating the FFmpeg engine.',
          });
          this.#terminateEngine();
-          this.#setState({ status: 'recovering', previousMode: mode });
+          this.#setState({
+            status: 'recovering',
+            previousMode: refreshedMode,
+          });
          try {
            await this.initialize();
          } catch {
@@ -711,7 +846,7 @@ export class EngineManager {
          if (capabilities) {
            this.#setState({
              status: 'ready',
-              mode,
+              mode: refreshedMode,
              capabilities,
              warning: this.#warning,
            });
@@ -721,6 +856,71 @@ export class EngineManager {
    }
  }

+  async #refreshCoreBeforeProbe(signal?: AbortSignal): Promise<void> {
+    if (!shouldRefreshCoreBeforeProbe()) return;
+    if (signal?.aborted) {
+      throw new EngineError('cancelled', 'The media probe was cancelled.');
+    }
+    const mode = this.#mode;
+    const capabilities = this.#capabilities;
+    const warning = this.#warning;
+    if (!mode || !capabilities || this.#state.status !== 'ready') {
+      throw new EngineError('load-failed', 'The FFmpeg engine is not ready.');
+    }
+
+    this.#terminateEngine();
+    this.#setState({ status: 'recovering', previousMode: mode, warning });
+    try {
+      await this.#loadMode(mode, warning, { mode, capabilities });
+    } catch (firstError) {
+      if (mode !== 'multithread') {
+        this.#terminateEngine();
+        const loadError = new EngineError(
+          'load-failed',
+          'The FFmpeg core could not be refreshed for media inspection.',
+          {
+            cause: firstError,
+            details: describeInitializationFailure(firstError),
+          }
+        );
+        this.#setState({ status: 'error', error: loadError });
+        throw loadError;
+      }
+
+      this.#terminateEngine();
+      const fallbackWarning = {
+        code: 'multithread-load-failed' as const,
+        message:
+          'The multithread core failed to reload. The app recovered with the single-thread compatibility core.',
+      };
+      this.#setState({
+        status: 'recovering',
+        previousMode: 'multithread',
+        warning: fallbackWarning,
+      });
+      try {
+        // Capabilities are mode-specific; discover a fresh single-thread set.
+        await this.#loadMode('single-thread', fallbackWarning);
+      } catch (fallbackError) {
+        const details = [
+          `Multithread core: ${describeInitializationFailure(firstError)}`,
+          `Single-thread core: ${describeInitializationFailure(fallbackError)}`,
+        ].join('\n');
+        this.#terminateEngine();
+        const loadError = new EngineError(
+          'load-failed',
+          'Neither FFmpeg execution core could be refreshed for media inspection.',
+          { cause: fallbackError, details }
+        );
+        this.#setState({ status: 'error', error: loadError });
+        throw loadError;
+      }
+    }
+    if (signal?.aborted) {
+      throw new EngineError('cancelled', 'The media probe was cancelled.');
+    }
+  }
+
  async cancelActive(): Promise<void> {
    const activeJobId = this.#activeJobId;
    const previousMode = this.#mode;
@@ -760,7 +960,10 @@ export class EngineManager {
    this.#contactSheetsSinceLoad = 0;
  }

-  async #recycleExecutionCoreIfNeeded(nextOperation: string): Promise<void> {
+  async #recycleExecutionCoreIfNeeded(
+    nextOperation: string,
+    operationReserved = false
+  ): Promise<void> {
    if (
      !shouldRecycleExecutionCore(
        this.#executionsSinceLoad,
@@ -789,7 +992,14 @@ export class EngineManager {
    });
    this.#terminateEngine();
    this.#setState({ status: 'recovering', previousMode });
-    await this.initialize();
+    if (operationReserved) {
+      this.#loadPromise = this.#initializeInternal().finally(() => {
+        this.#loadPromise = null;
+      });
+      await this.#loadPromise;
+    } else {
+      await this.initialize();
+    }
  }

  #setState(state: EngineState): void {
--- a/src/index.css
+++ b/src/index.css
@@ -561,12 +561,16 @@ select:disabled {
  color: #2c7d63 !important;
 }

+.phase--idle {
+  color: #2c7d63 !important;
+}
+
 .phase--probing {
  color: #8b6a20 !important;
 }

 .phase--error {
-  color: var(--toolbox-danger) !important;
+  color: #8b6a20 !important;
 }

 .media-bin__empty {
@@ -779,6 +783,18 @@ select:disabled {
  font-size: 0.68rem;
 }

+.stream-picker__empty {
+  display: flex;
+  flex-wrap: wrap;
+  align-items: center;
+  justify-content: space-between;
+  gap: 0.75rem;
+}
+
+.stream-picker__empty .button {
+  flex: none;
+}
+
 .stream-kind {
  display: inline-flex;
  align-items: center;
@@ -1759,6 +1775,15 @@ progress::-moz-progress-bar {
  padding: 0.8rem;
 }

+.inspector-section > .notice {
+  align-items: center;
+  margin: 0;
+}
+
+.inspector-section > .notice > div {
+  flex: 1;
+}
+
 .inspector-section h3 {
  margin: 0.45rem 0 0;
 }
--- a/src/media/browser-metadata.ts
+++ b/src/media/browser-metadata.ts
@@ -0,0 +1,282 @@
+import {
+  isAudioMimeType,
+  isVideoMimeType,
+  mimeTypeFromFileName,
+} from './mime-types';
+
+export type BrowserMediaKind = 'audio' | 'video' | 'unknown';
+
+export type BrowserMetadataErrorCode = 'aborted' | 'load-error' | 'timeout';
+
+export interface BrowserMediaFileInfo {
+  readonly name: string;
+  readonly sizeBytes: number;
+  readonly declaredMimeType?: string;
+  readonly inferredMimeType?: string;
+  readonly lastModified: number;
+}
+
+/**
+ * Lightweight metadata exposed by the browser's native media element.
+ *
+ * This intentionally does not pretend to replace ffprobe: codec names,
+ * complete stream lists, chapters, tags and dispositions remain unknown.
+ */
+export interface BrowserMediaMetadata {
+  readonly source: 'browser';
+  readonly file: BrowserMediaFileInfo;
+  readonly kind: BrowserMediaKind;
+  readonly durationSeconds?: number;
+  readonly width?: number;
+  readonly height?: number;
+  readonly hasAudio?: boolean;
+  readonly hasVideo?: boolean;
+}
+
+export interface BrowserMetadataOptions {
+  readonly signal?: AbortSignal;
+  readonly timeoutMilliseconds?: number;
+  /**
+   * Test seam for the DOM-owned media element. Production callers normally
+   * leave this unset.
+   */
+  readonly createMediaElement?: (
+    kind: Exclude<BrowserMediaKind, 'unknown'>
+  ) => HTMLMediaElement;
+}
+
+export class BrowserMetadataError extends Error {
+  readonly code: BrowserMetadataErrorCode;
+
+  constructor(code: BrowserMetadataErrorCode, message: string) {
+    super(message);
+    this.name = 'BrowserMetadataError';
+    this.code = code;
+  }
+}
+
+const DEFAULT_BROWSER_METADATA_TIMEOUT_MILLISECONDS = 15_000;
+
+interface MediaElementWithAudioHints extends HTMLMediaElement {
+  readonly audioTracks?: { readonly length: number };
+  readonly mozHasAudio?: boolean;
+}
+
+export function browserMediaFileInfo(file: File): BrowserMediaFileInfo {
+  return {
+    name: file.name,
+    sizeBytes: file.size,
+    declaredMimeType: normalizeMimeType(file.type),
+    inferredMimeType: mimeTypeFromFileName(file.name),
+    lastModified: file.lastModified,
+  };
+}
+
+export function inferBrowserMediaKind(file: File): BrowserMediaKind {
+  const declaredMimeType = normalizeMimeType(file.type);
+  const inferredMimeType = mimeTypeFromFileName(file.name);
+  const mimeType =
+    declaredMimeType !== undefined &&
+    (isAudioMimeType(declaredMimeType) || isVideoMimeType(declaredMimeType))
+      ? declaredMimeType
+      : inferredMimeType;
+
+  if (mimeType === undefined) return 'unknown';
+  if (isVideoMimeType(mimeType)) return 'video';
+  if (isAudioMimeType(mimeType)) return 'audio';
+  return 'unknown';
+}
+
+/**
+ * Reads only metadata the browser can expose without FFmpeg. The supplied
+ * object URL remains owned by the caller and is never revoked here.
+ */
+export function inspectBrowserMediaMetadata(
+  file: File,
+  objectUrl: string,
+  options: BrowserMetadataOptions = {}
+): Promise<BrowserMediaMetadata> {
+  const declaredKind = inferBrowserMediaKind(file);
+  const elementKind = declaredKind === 'audio' ? 'audio' : 'video';
+  const createMediaElement =
+    options.createMediaElement ??
+    ((kind: 'audio' | 'video') => document.createElement(kind));
+  const element = createMediaElement(elementKind);
+  const timeoutMilliseconds =
+    options.timeoutMilliseconds ??
+    DEFAULT_BROWSER_METADATA_TIMEOUT_MILLISECONDS;
+
+  if (options.signal?.aborted === true) {
+    return Promise.reject(abortedError());
+  }
+
+  return new Promise((resolve, reject) => {
+    let settled = false;
+
+    const cleanup = () => {
+      clearTimeout(timeoutId);
+      element.removeEventListener('loadedmetadata', handleLoadedMetadata);
+      element.removeEventListener('error', handleError);
+      element.removeEventListener('abort', handleElementAbort);
+      options.signal?.removeEventListener('abort', handleSignalAbort);
+      element.removeAttribute('src');
+      try {
+        element.load();
+      } catch {
+        // The caller owns the object URL; releasing this detached element is
+        // best-effort and must not turn successful metadata into a failure.
+      }
+    };
+    const finish = (
+      outcome:
+        | { readonly ok: true; readonly value: BrowserMediaMetadata }
+        | { readonly ok: false; readonly error: BrowserMetadataError }
+    ) => {
+      if (settled) return;
+      settled = true;
+      cleanup();
+      if (outcome.ok) resolve(outcome.value);
+      else reject(outcome.error);
+    };
+    const handleLoadedMetadata = () => {
+      finish({
+        ok: true,
+        value: metadataFromElement(file, declaredKind, element),
+      });
+    };
+    const handleError = () => {
+      finish({
+        ok: false,
+        error: new BrowserMetadataError(
+          'load-error',
+          `The browser could not read metadata from ${file.name}.`
+        ),
+      });
+    };
+    const handleElementAbort = () => {
+      finish({
+        ok: false,
+        error: new BrowserMetadataError(
+          'load-error',
+          `The browser stopped reading metadata from ${file.name}.`
+        ),
+      });
+    };
+    const handleSignalAbort = () => {
+      finish({ ok: false, error: abortedError() });
+    };
+
+    element.addEventListener('loadedmetadata', handleLoadedMetadata);
+    element.addEventListener('error', handleError);
+    element.addEventListener('abort', handleElementAbort);
+    options.signal?.addEventListener('abort', handleSignalAbort, {
+      once: true,
+    });
+    const timeoutId = setTimeout(
+      () => {
+        finish({
+          ok: false,
+          error: new BrowserMetadataError(
+            'timeout',
+            `Browser metadata loading exceeded ${String(
+              Math.ceil(timeoutMilliseconds / 1_000)
+            )} seconds.`
+          ),
+        });
+      },
+      Math.max(0, timeoutMilliseconds)
+    );
+
+    element.preload = 'metadata';
+    element.src = objectUrl;
+    try {
+      element.load();
+    } catch {
+      finish({
+        ok: false,
+        error: new BrowserMetadataError(
+          'load-error',
+          `The browser could not start reading metadata from ${file.name}.`
+        ),
+      });
+    }
+  });
+}
+
+function metadataFromElement(
+  file: File,
+  declaredKind: BrowserMediaKind,
+  element: HTMLMediaElement
+): BrowserMediaMetadata {
+  const isVideoElement = element instanceof HTMLVideoElement;
+  const width = isVideoElement
+    ? positiveFiniteNumber(element.videoWidth)
+    : undefined;
+  const height = isVideoElement
+    ? positiveFiniteNumber(element.videoHeight)
+    : undefined;
+  // A zero-sized <video> can still be the correct, playable element for an
+  // audio-only MP4 or another video container. Treat missing dimensions as
+  // inconclusive instead of claiming that no video-style player is usable.
+  const hasVideo = isVideoElement
+    ? width !== undefined
+      ? true
+      : undefined
+    : false;
+  const hasAudio = audioPresence(element, isVideoElement);
+  const kind =
+    hasVideo === true
+      ? 'video'
+      : hasAudio === true || element instanceof HTMLAudioElement
+        ? 'audio'
+        : declaredKind;
+
+  return {
+    source: 'browser',
+    file: browserMediaFileInfo(file),
+    kind,
+    durationSeconds: nonNegativeFiniteNumber(element.duration),
+    width,
+    height,
+    hasAudio,
+    hasVideo,
+  };
+}
+
+function audioPresence(
+  element: HTMLMediaElement,
+  isVideoElement: boolean
+): boolean | undefined {
+  if (!isVideoElement) return true;
+
+  const withAudioHints = element as MediaElementWithAudioHints;
+  if (withAudioHints.audioTracks !== undefined) {
+    return withAudioHints.audioTracks.length > 0;
+  }
+  if (typeof withAudioHints.mozHasAudio === 'boolean') {
+    return withAudioHints.mozHasAudio;
+  }
+  return undefined;
+}
+
+function normalizeMimeType(mimeType: string): string | undefined {
+  const normalized = mimeType.trim().toLowerCase().split(';')[0]?.trim();
+  return normalized === undefined || normalized.length === 0
+    ? undefined
+    : normalized;
+}
+
+function positiveFiniteNumber(value: number): number | undefined {
+  return Number.isFinite(value) && value > 0 ? value : undefined;
+}
+
+function nonNegativeFiniteNumber(value: number): number | undefined {
+  return Number.isFinite(value) && value >= 0 ? value : undefined;
+}
+
+function abortedError(): BrowserMetadataError {
+  return new BrowserMetadataError(
+    'aborted',
+    'Browser metadata loading was cancelled.'
+  );
+}
--- a/src/media/index.ts
+++ b/src/media/index.ts
@@ -1,4 +1,5 @@
 export * from './browser-playback';
+export * from './browser-metadata';
 export * from './chapter-time-base';
 export * from './duration';
 export * from './media.types';
--- a/src/toolbox/manifest.source.json
+++ b/src/toolbox/manifest.source.json
@@ -3,7 +3,7 @@
  "schemaVersion": 1,
  "id": "de.add-ideas.av-tools",
  "name": "Audio & Video Tools",
-  "version": "0.2.1",
+  "version": "0.3.0",
  "description": "Convert and lightly edit audio and video locally in the browser.",
  "entry": "./",
  "icon": "./favicon.svg",
--- a/src/version.ts
+++ b/src/version.ts
@@ -1,4 +1,4 @@
-export const APP_VERSION = '0.2.1';
+export const APP_VERSION = '0.3.0';
 export const FFMPEG_WRAPPER_VERSION = '0.12.15';
 export const FFMPEG_UTIL_VERSION = '0.12.2';
 export const FFMPEG_CORE_VERSION = '0.12.10';
--- a/tests/browser/application.spec.ts
+++ b/tests/browser/application.spec.ts
@@ -1,6 +1,7 @@
 import { expect, test } from '@playwright/test';
 import {
  observeRuntime,
+  PRIMARY_FIXTURE,
  startNestedStaticServer,
  type NestedStaticServer,
 } from './browser-helpers';
@@ -119,6 +120,38 @@ test.describe('static application and Toolbox shell', () => {
    await expect(inspectorDrawer).toBeHidden();
    await expect(inspector).toBeFocused();
  });
+
+  test('shows native preview metadata without loading the FFmpeg runtime', async ({
+    page,
+  }) => {
+    const runtime = observeRuntime(page);
+    await page.goto('/');
+
+    await page
+      .locator('input[type="file"][accept*="audio"]')
+      .first()
+      .setInputFiles(PRIMARY_FIXTURE);
+
+    await expect(page.locator('.quick-preview video')).toBeVisible();
+    const card = page
+      .locator('.media-card')
+      .filter({ hasText: 'pattern-av.mp4' });
+    await expect(card.locator('.phase--idle')).toContainText(
+      'Ready to play · Details on demand'
+    );
+    await expect(card).toContainText(/\d+:\d{2}\.\d{2}/u);
+    expect(
+      runtime.requests.some((url) => url.includes('/vendor/ffmpeg/'))
+    ).toBe(false);
+
+    await page.getByRole('tab', { name: 'Edit' }).click();
+    await expect(
+      page.getByRole('button', { name: 'Inspect & render timeline' })
+    ).toBeEnabled();
+    expect(
+      runtime.requests.some((url) => url.includes('/vendor/ffmpeg/'))
+    ).toBe(false);
+  });
 });

 test.describe('nested static deployment and Toolbox context', () => {
--- a/tests/browser/browser-helpers.ts
+++ b/tests/browser/browser-helpers.ts
@@ -7,6 +7,7 @@ import { tmpdir } from 'node:os';
 import { dirname, extname, join, resolve, sep } from 'node:path';
 import { fileURLToPath } from 'node:url';
 import type { ConsoleMessage, Page, Request, Response } from '@playwright/test';
+import { expect } from '@playwright/test';

 export const REPOSITORY_ROOT = resolve(
  dirname(fileURLToPath(import.meta.url)),
@@ -19,6 +20,20 @@ export const GENERATED_FIXTURES = join(
 );
 export const PRIMARY_FIXTURE = join(GENERATED_FIXTURES, 'pattern-av.mp4');

+export async function inspectMediaDetails(
+  page: Page,
+  fileName: string
+): Promise<void> {
+  const card = page.locator('.media-card').filter({ hasText: fileName });
+  const inspect = page.getByRole('button', {
+    name: `Inspect details for ${fileName}`,
+  });
+  if ((await inspect.count()) > 0) await inspect.click();
+  await expect(card.locator('.phase--ready')).toBeVisible({
+    timeout: 120_000,
+  });
+}
+
 const NESTED_PREFIX = '/deep/nested/av/';
 const SECURITY_HEADERS = {
  'Cross-Origin-Embedder-Policy': 'require-corp',
--- a/tests/browser/ffmpeg-runtime.spec.ts
+++ b/tests/browser/ffmpeg-runtime.spec.ts
@@ -6,6 +6,7 @@ import { expect, test } from '@playwright/test';
 import {
  createCancellationFixture,
  GENERATED_FIXTURES,
+  inspectMediaDetails,
  observeRuntime,
  PRIMARY_FIXTURE,
  type TemporaryMediaFixture,
@@ -99,8 +100,9 @@ test.describe.serial('real pinned FFmpeg browser runtime', () => {
    ).toBe(false);

    await mediaInput(page).setInputFiles(PRIMARY_FIXTURE);
+    await inspectMediaDetails(page, 'pattern-av.mp4');
    await expect(page.locator('.source-summary .phase--ready')).toHaveText(
-      'Ready',
+      'Details ready',
      { timeout: 120_000 }
    );
    await page.getByRole('button', { name: 'Convert', exact: true }).click();
@@ -184,8 +186,9 @@ test.describe.serial('real pinned FFmpeg browser runtime', () => {
    ).toBe(false);
    await mediaInput(page).setInputFiles(PRIMARY_FIXTURE);

+    await inspectMediaDetails(page, 'pattern-av.mp4');
    await expect(page.locator('.source-summary .phase--ready')).toHaveText(
-      'Ready',
+      'Details ready',
      { timeout: 120_000 }
    );
    await expect(page.locator('.source-summary')).toContainText(
@@ -275,6 +278,7 @@ test.describe.serial('real pinned FFmpeg browser runtime', () => {
    await mediaInput(page)
      .first()
      .setInputFiles(join(GENERATED_FIXTURES, 'compatible-a.mp4'));
+    await inspectMediaDetails(page, 'compatible-a.mp4');
    await expect(
      page
        .locator('.media-card')
@@ -329,8 +333,9 @@ test.describe.serial('real pinned FFmpeg browser runtime', () => {
    await page.goto('/');
    await selectSingleThread(page);
    await mediaInput(page).setInputFiles(cancellationFixture.filePath);
+    await inspectMediaDetails(page, basename(cancellationFixture.filePath));
    await expect(page.locator('.source-summary .phase--ready')).toHaveText(
-      'Ready',
+      'Details ready',
      { timeout: 120_000 }
    );

@@ -357,8 +362,9 @@ test.describe.serial('real pinned FFmpeg browser runtime', () => {
      })
      .click();
    await mediaInput(page).setInputFiles(PRIMARY_FIXTURE);
+    await inspectMediaDetails(page, 'pattern-av.mp4');
    await expect(page.locator('.source-summary .phase--ready')).toHaveText(
-      'Ready',
+      'Details ready',
      { timeout: 120_000 }
    );
    await page.getByRole('button', { name: 'Convert', exact: true }).click();
@@ -388,10 +394,15 @@ test.describe.serial('real pinned FFmpeg browser runtime', () => {
    const queuedCard = page.locator('.media-card').filter({
      hasText: 'pattern-av.mp4',
    });
+    await page
+      .getByRole('button', {
+        name: `Inspect details for ${activeName}`,
+      })
+      .click();
    await expect(activeCard.locator('.phase--probing')).toBeVisible({
      timeout: 30_000,
    });
-    await expect(queuedCard.locator('.phase--queued')).toBeVisible();
+    await expect(queuedCard.locator('.phase--idle')).toBeVisible();

    await page.getByRole('button', { name: 'Remove pattern-av.mp4' }).click();
    await page.getByRole('button', { name: `Remove ${activeName}` }).click();
@@ -401,8 +412,9 @@ test.describe.serial('real pinned FFmpeg browser runtime', () => {
    ).toBeEnabled({ timeout: 120_000 });

    await mediaInput(page).setInputFiles(PRIMARY_FIXTURE);
+    await inspectMediaDetails(page, 'pattern-av.mp4');
    await expect(page.locator('.source-summary .phase--ready')).toHaveText(
-      'Ready',
+      'Details ready',
      { timeout: 120_000 }
    );
    await expect(page.getByRole('alert')).toHaveCount(0);
--- a/tests/browser/fixture-recovery.spec.ts
+++ b/tests/browser/fixture-recovery.spec.ts
@@ -4,6 +4,7 @@ import { join } from 'node:path';
 import { expect, test, type Page } from '@playwright/test';
 import {
  GENERATED_FIXTURES,
+  inspectMediaDetails,
  observeRuntime,
  PRIMARY_FIXTURE,
  type RuntimeObservation,
@@ -51,8 +52,9 @@ test.describe
    await mediaInput(page).setInputFiles(
      join(GENERATED_FIXTURES, 'attached-cover.mp3')
    );
+    await inspectMediaDetails(page, 'attached-cover.mp3');
    await expect(page.locator('.source-summary .phase--ready')).toHaveText(
-      'Ready',
+      'Details ready',
      { timeout: 60_000 }
    );
    await expect(page.locator('.source-summary')).toContainText(
@@ -108,13 +110,23 @@ test.describe
    await mediaInput(page).setInputFiles(
      join(GENERATED_FIXTURES, 'truncated.mp4')
    );
+    await page
+      .getByRole('button', {
+        name: 'Inspect details for truncated.mp4',
+      })
+      .click();
    const malformedCard = page
      .locator('.media-card')
      .filter({ hasText: 'truncated.mp4' });
    await expect(malformedCard.locator('.phase--error')).toContainText(
-      'ffprobe did not find any media streams.',
+      'File ready · Details unavailable',
      { timeout: 30_000 }
    );
+    await expect(
+      page.getByRole('button', {
+        name: 'Retry detailed inspection for truncated.mp4',
+      })
+    ).toHaveAttribute('title', 'ffprobe did not find any media streams.');
    expect(Date.now() - probeStartedAt).toBeLessThan(30_000);
    await expect(
      page
@@ -123,6 +135,7 @@ test.describe
    ).toBeVisible();

    await mediaInput(page).setInputFiles(PRIMARY_FIXTURE);
+    await inspectMediaDetails(page, 'pattern-av.mp4');
    const validCard = page
      .locator('.media-card')
      .filter({ hasText: 'pattern-av.mp4' });
--- a/tests/browser/large-media-preview.spec.ts
+++ b/tests/browser/large-media-preview.spec.ts
@@ -6,7 +6,7 @@ import { expect, test } from '@playwright/test';

 const mediaPath = process.env.AV_TOOLS_LARGE_MEDIA;

-test('plays a recognized large local video while inspection continues', async ({
+test('plays a recognized large local video before detailed inspection', async ({
  page,
 }) => {
  test.skip(
@@ -27,7 +27,15 @@ test('plays a recognized large local video while inspection continues', async ({
  await expect(preview).toBeVisible({ timeout: 15_000 });
  const previewVisibleMilliseconds = Date.now() - startedAt;
  expect(previewVisibleMilliseconds).toBeLessThan(15_000);
-  await expect(card.locator('.phase--probing')).toBeVisible();
+  await expect(card.locator('.phase--idle')).toContainText('Details on demand');
+  await expect(card).toContainText(/43:42\.\d{2}/u, { timeout: 15_000 });
+  expect(
+    await page.evaluate(() =>
+      performance
+        .getEntriesByType('resource')
+        .some((entry) => entry.name.includes('/vendor/ffmpeg/'))
+    )
+  ).toBe(false);

  const elementIdentity = await preview.evaluate((element) => {
    element.dataset.evidenceIdentity = crypto.randomUUID();
@@ -50,9 +58,11 @@ test('plays a recognized large local video while inspection continues', async ({
    )
    .toBeGreaterThan(0);

-  await expect(card.locator('.phase--ready')).toBeVisible({
-    timeout: 330_000,
-  });
+  await page
+    .getByRole('button', { name: `Inspect details for ${name}` })
+    .click();
+  await expect(card.locator('.phase--probing')).toBeVisible();
+  await expect(card.locator('.phase--ready')).toBeVisible({ timeout: 120_000 });
  await expect(preview).toHaveAttribute(
    'data-evidence-identity',
    elementIdentity
--- a/tests/browser/operation-matrix.spec.ts
+++ b/tests/browser/operation-matrix.spec.ts
@@ -31,6 +31,9 @@ async function importMedia(
  await mediaInput(page).setInputFiles(names.map((name) => fixture(name)));
  for (const name of names) {
    const card = page.locator('.media-card').filter({ hasText: name });
+    await page
+      .getByRole('button', { name: `Inspect details for ${name}` })
+      .click();
    await expect(card.locator('.phase--ready')).toBeVisible({
      timeout: 120_000,
    });
@@ -210,6 +213,11 @@ test.describe.serial('real ffmpeg.wasm operation matrix', () => {
    await test.step('queues a second browser job, cancels the active job and runs the waiting job after recovery', async () => {
      const sourceName = basename(cancellationFixture.filePath);
      await mediaInput(page).setInputFiles(cancellationFixture.filePath);
+      await page
+        .getByRole('button', {
+          name: `Inspect details for ${sourceName}`,
+        })
+        .click();
      await expect(
        page
          .locator('.media-card')
@@ -1055,6 +1063,11 @@ test.describe.serial('real ffmpeg.wasm operation matrix', () => {
        mimeType: 'video/x-matroska',
        buffer: readFileSync(muxed.filePath),
      });
+      await page
+        .getByRole('button', {
+          name: 'Inspect details for subtitled-source.mkv',
+        })
+        .click();
      await expect(
        page
          .locator('.media-card')
--- a/tests/browser/performance.spec.ts
+++ b/tests/browser/performance.spec.ts
@@ -103,8 +103,9 @@ async function runMode(

    const probeStarted = await monotonicNow(page);
    await mediaInput(page).setInputFiles(fixturePath);
+    await page.getByRole('button', { name: /^Inspect details for /u }).click();
    await expect(page.locator('.source-summary .phase--ready')).toHaveText(
-      'Ready',
+      'Details ready',
      { timeout: 120_000 }
    );
    const probeMs = (await monotonicNow(page)) - probeStarted;
--- a/tests/browser/ui-workflows.spec.ts
+++ b/tests/browser/ui-workflows.spec.ts
@@ -21,8 +21,11 @@ test('covers drop, editor keyboard/drag controls, cache, and project reattachmen
  await page.getByLabel('Engine mode').selectOption('force-single-thread');

  await dropFixture(page, PRIMARY_FIXTURE, 'video/mp4');
+  await page
+    .getByRole('button', { name: 'Inspect details for pattern-av.mp4' })
+    .click();
  await expect(page.locator('.source-summary .phase--ready')).toHaveText(
-    'Ready',
+    'Details ready',
    { timeout: 120_000 }
  );
  await expect(page.locator('.quick-preview video')).toHaveAttribute(
@@ -47,6 +50,9 @@ test('covers drop, editor keyboard/drag controls, cache, and project reattachmen
  await page.getByRole('tab', { name: 'Edit' }).click();
  const compatibleB = join(GENERATED_FIXTURES, 'compatible-b.mp4');
  await mediaInput(page).setInputFiles(compatibleB);
+  await page
+    .getByRole('button', { name: 'Inspect details for compatible-b.mp4' })
+    .click();
  await expect(page.locator('.media-card .phase--ready')).toHaveCount(2, {
    timeout: 120_000,
  });
@@ -127,6 +133,12 @@ test('covers drop, editor keyboard/drag controls, cache, and project reattachmen

  page.on('dialog', (dialog) => void dialog.accept());
  await mediaInput(page).setInputFiles([PRIMARY_FIXTURE, compatibleB]);
+  await page
+    .getByRole('button', { name: 'Inspect details for pattern-av.mp4' })
+    .click();
+  await page
+    .getByRole('button', { name: 'Inspect details for compatible-b.mp4' })
+    .click();
  await expect(page.locator('.media-card .phase--ready')).toHaveCount(2, {
    timeout: 120_000,
  });
--- a/tests/unit/components/media-bin.test.tsx
+++ b/tests/unit/components/media-bin.test.tsx
@@ -0,0 +1,93 @@
+import { cleanup, render, screen } from '@testing-library/react';
+import userEvent from '@testing-library/user-event';
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import type { ImportedMediaAsset } from '../../../src/app/application-state';
+import { MediaBin } from '../../../src/components/MediaBin';
+
+afterEach(cleanup);
+
+describe('MediaBin', () => {
+  it('shows browser metadata and offers optional detailed inspection', async () => {
+    const user = userEvent.setup();
+    const onInspect = vi.fn();
+    const file = new File(['video'], 'lecture.mp4', { type: 'video/mp4' });
+    const asset: ImportedMediaAsset = {
+      id: 'lecture',
+      file,
+      objectUrl: 'blob:lecture',
+      phase: 'idle',
+      browserMetadata: {
+        source: 'browser',
+        file: {
+          name: file.name,
+          sizeBytes: file.size,
+          declaredMimeType: file.type,
+          inferredMimeType: file.type,
+          lastModified: file.lastModified,
+        },
+        kind: 'video',
+        durationSeconds: 2_622.48,
+        width: 640,
+        height: 480,
+        hasVideo: true,
+      },
+    };
+
+    render(
+      <MediaBin
+        assets={[asset]}
+        selectedId={asset.id}
+        onSelect={vi.fn()}
+        onInspect={onInspect}
+        onRemove={vi.fn()}
+      />
+    );
+
+    expect(screen.getByText(/43:42\.48/u)).toBeVisible();
+    expect(screen.getByText('Ready to play · Details on demand')).toBeVisible();
+    expect(screen.getByText('lecture.mp4').closest('button')).toHaveAttribute(
+      'aria-pressed',
+      'true'
+    );
+    await user.click(
+      screen.getByRole('button', {
+        name: 'Inspect details for lecture.mp4',
+      })
+    );
+    expect(onInspect).toHaveBeenCalledWith(asset.id);
+  });
+
+  it('keeps a source ready to play after detailed inspection fails', () => {
+    const file = new File(['video'], 'lecture.mp4', { type: 'video/mp4' });
+    const asset: ImportedMediaAsset = {
+      id: 'lecture',
+      file,
+      objectUrl: 'blob:lecture',
+      phase: 'error',
+      error: 'Media inspection exceeded its safety limit.',
+    };
+
+    render(
+      <MediaBin
+        assets={[asset]}
+        onSelect={vi.fn()}
+        onInspect={vi.fn()}
+        onRemove={vi.fn()}
+      />
+    );
+
+    expect(screen.getByText('File ready · Details unavailable')).toBeVisible();
+    expect(
+      screen.getByRole('button', {
+        name: 'Retry detailed inspection for lecture.mp4',
+      })
+    ).toBeEnabled();
+    expect(
+      screen.getByRole('button', {
+        name: 'Retry detailed inspection for lecture.mp4',
+      })
+    ).toHaveAccessibleDescription(
+      'Media inspection exceeded its safety limit.'
+    );
+  });
+});
--- a/tests/unit/components/media-preview.test.tsx
+++ b/tests/unit/components/media-preview.test.tsx
@@ -43,7 +43,7 @@ describe('MediaPreview', () => {
    expect(progressiveVideo).toHaveAttribute('src', probingAsset.objectUrl);
    expect(
      screen.getByText(
-        'Local source preview · Media inspection continues in the background.'
+        'Local source preview · Detailed inspection runs separately.'
      )
    ).toBeVisible();

@@ -61,6 +61,64 @@ describe('MediaPreview', () => {
    expect(container.querySelector('video')).toBe(progressiveVideo);
  });

+  it('keeps browser playback mounted after detailed inspection fails', () => {
+    const asset: ImportedMediaAsset = {
+      id: 'asset-probe-error',
+      file: new File(['video'], 'lecture.mp4', { type: 'video/mp4' }),
+      objectUrl: 'blob:probe-error',
+      phase: 'error',
+      error: 'Detailed inspection timed out.',
+    };
+
+    const { container } = render(<MediaPreview asset={asset} />);
+
+    expect(container.querySelector('video')).toHaveAttribute(
+      'src',
+      asset.objectUrl
+    );
+    expect(
+      screen.getByText(
+        'Local source preview · Detailed inspection unavailable.'
+      )
+    ).toBeVisible();
+  });
+
+  it('keeps the video-container player when browser metadata has no track hints', () => {
+    const file = new File(['audio-only'], 'audio-only.mp4', {
+      type: 'video/mp4',
+    });
+    const initial: ImportedMediaAsset = {
+      id: 'asset-audio-only-container',
+      file,
+      objectUrl: 'blob:audio-only-container',
+      phase: 'idle',
+    };
+    const { container, rerender } = render(<MediaPreview asset={initial} />);
+    const player = requiredElement(container.querySelector('video'));
+
+    rerender(
+      <MediaPreview
+        asset={{
+          ...initial,
+          browserMetadata: {
+            source: 'browser',
+            file: {
+              name: file.name,
+              sizeBytes: file.size,
+              declaredMimeType: file.type,
+              inferredMimeType: file.type,
+              lastModified: file.lastModified,
+            },
+            kind: 'video',
+            durationSeconds: 8,
+          },
+        }}
+      />
+    );
+
+    expect(container.querySelector('video')).toBe(player);
+  });
+
  it('offers bounded configurable proxy settings after playback fails', async () => {
    const user = userEvent.setup();
    const onCreateProxy = vi.fn();
--- a/tests/unit/components/quick-convert.test.tsx
+++ b/tests/unit/components/quick-convert.test.tsx
@@ -16,6 +16,66 @@ import type { UserExportPreset } from '../../../src/presets';
 afterEach(cleanup);

 describe('QuickConvert', () => {
+  it('keeps an uninspected source usable and requests stream detection with export', async () => {
+    const user = userEvent.setup();
+    const onInspect = vi.fn();
+    const onExport = vi.fn<(configuration: QuickExportConfiguration) => void>();
+    const file = new File(['media'], 'lecture.mp4', { type: 'video/mp4' });
+    const asset: ImportedMediaAsset = {
+      id: 'asset-basic',
+      file,
+      objectUrl: 'blob:asset-basic',
+      phase: 'idle',
+      browserMetadata: {
+        source: 'browser',
+        file: {
+          name: file.name,
+          sizeBytes: file.size,
+          declaredMimeType: file.type,
+          inferredMimeType: file.type,
+          lastModified: file.lastModified,
+        },
+        kind: 'video',
+        durationSeconds: 2_622.48,
+        width: 640,
+        height: 480,
+        hasVideo: true,
+      },
+    };
+
+    render(
+      <QuickConvert
+        asset={asset}
+        engineState={readyEngine()}
+        busy={false}
+        onInspect={onInspect}
+        onExport={onExport}
+      />
+    );
+
+    expect(screen.getByText(/43:42\.48/u)).toBeVisible();
+    expect(screen.getByText('Ready to play')).toBeVisible();
+    await user.click(
+      screen.getByRole('button', { name: 'Inspect details now' })
+    );
+    expect(onInspect).toHaveBeenCalledOnce();
+
+    await user.click(screen.getByRole('button', { name: 'Inspect & convert' }));
+    expect(onExport).toHaveBeenCalledWith(
+      expect.objectContaining({
+        operation: 'convert',
+        selectDetectedStreams: true,
+        streamSelection: {
+          video: [],
+          audio: [],
+          subtitles: [],
+          attachments: [],
+          data: [],
+        },
+      })
+    );
+  });
+
  it('labels a submission honestly when another operation is active', () => {
    render(
      <QuickConvert
--- a/tests/unit/ffmpeg-engine-arguments.test.ts
+++ b/tests/unit/ffmpeg-engine-arguments.test.ts
@@ -7,9 +7,11 @@ import {
  MAX_PROBE_TIMEOUT_MILLISECONDS,
  MIN_PROBE_TIMEOUT_MILLISECONDS,
  MULTITHREAD_CODEC_THREAD_LIMIT,
+  canReuseProbeCapabilities,
  engineJobTimeoutMilliseconds,
  prepareEngineArguments,
  probeTimeoutMilliseconds,
+  shouldRefreshCoreBeforeProbe,
  shouldRecycleExecutionCore,
 } from '../../src/ffmpeg/EngineManager';

@@ -127,6 +129,40 @@ describe('probeTimeoutMilliseconds', () => {
  });
 });

+describe('Firefox probe core refresh policy', () => {
+  it('refreshes only affected Firefox-family runtimes', () => {
+    expect(
+      shouldRefreshCoreBeforeProbe(
+        'Mozilla/5.0 (X11; Linux x86_64; rv:142.0) Gecko/20100101 Firefox/142.0'
+      )
+    ).toBe(true);
+    expect(
+      shouldRefreshCoreBeforeProbe(
+        'Mozilla/5.0 (iPhone; CPU iPhone OS 18_6 like Mac OS X) FxiOS/142.0'
+      )
+    ).toBe(true);
+    expect(
+      shouldRefreshCoreBeforeProbe(
+        'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 Chrome/140.0 Safari/537.36'
+      )
+    ).toBe(false);
+    expect(shouldRefreshCoreBeforeProbe('')).toBe(false);
+  });
+
+  it('reuses cached capabilities only for the identical engine mode', () => {
+    expect(canReuseProbeCapabilities('multithread', 'multithread')).toBe(true);
+    expect(canReuseProbeCapabilities('single-thread', 'single-thread')).toBe(
+      true
+    );
+    expect(canReuseProbeCapabilities('multithread', 'single-thread')).toBe(
+      false
+    );
+    expect(canReuseProbeCapabilities('single-thread', 'multithread')).toBe(
+      false
+    );
+  });
+});
+
 describe('execution core recycling policy', () => {
  it('refreshes only after the bounded idle-core job budget is exhausted', () => {
    expect(shouldRecycleExecutionCore(MAX_EXECUTIONS_PER_ENGINE - 1)).toBe(
--- a/tests/unit/media/browser-metadata.test.ts
+++ b/tests/unit/media/browser-metadata.test.ts
@@ -0,0 +1,187 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+
+import {
+  BrowserMetadataError,
+  browserMediaFileInfo,
+  inferBrowserMediaKind,
+  inspectBrowserMediaMetadata,
+} from '../../../src/media/browser-metadata';
+
+afterEach(() => {
+  vi.useRealTimers();
+  vi.restoreAllMocks();
+});
+
+describe('browser media metadata', () => {
+  it('returns file information synchronously and infers useful media kinds', () => {
+    const file = new File(['media'], 'lecture.MP4', {
+      type: 'application/octet-stream',
+      lastModified: 123,
+    });
+
+    expect(browserMediaFileInfo(file)).toEqual({
+      name: 'lecture.MP4',
+      sizeBytes: 5,
+      declaredMimeType: 'application/octet-stream',
+      inferredMimeType: 'video/mp4',
+      lastModified: 123,
+    });
+    expect(inferBrowserMediaKind(file)).toBe('video');
+    expect(
+      inferBrowserMediaKind(
+        new File([], 'recording.bin', { type: 'audio/ogg; codecs=opus' })
+      )
+    ).toBe('audio');
+    expect(inferBrowserMediaKind(new File([], 'notes.txt'))).toBe('unknown');
+  });
+
+  it('loads duration and dimensions through a native video element', async () => {
+    const file = new File(['video'], 'lecture.mp4', { type: 'video/mp4' });
+    const video = document.createElement('video');
+    const load = vi.spyOn(video, 'load').mockImplementation(() => undefined);
+    defineNumber(video, 'duration', 2_622.48);
+    defineNumber(video, 'videoWidth', 640);
+    defineNumber(video, 'videoHeight', 480);
+    Object.defineProperty(video, 'audioTracks', {
+      configurable: true,
+      value: { length: 1 },
+    });
+
+    const resultPromise = inspectBrowserMediaMetadata(file, 'blob:lecture', {
+      createMediaElement: () => video,
+    });
+    video.dispatchEvent(new Event('loadedmetadata'));
+
+    await expect(resultPromise).resolves.toEqual({
+      source: 'browser',
+      file: {
+        name: 'lecture.mp4',
+        sizeBytes: 5,
+        declaredMimeType: 'video/mp4',
+        inferredMimeType: 'video/mp4',
+        lastModified: file.lastModified,
+      },
+      kind: 'video',
+      durationSeconds: 2_622.48,
+      width: 640,
+      height: 480,
+      hasAudio: true,
+      hasVideo: true,
+    });
+    expect(video.preload).toBe('metadata');
+    expect(video).not.toHaveAttribute('src');
+    expect(load).toHaveBeenCalledTimes(2);
+  });
+
+  it('uses an audio element and leaves unavailable details unknown', async () => {
+    const file = new File(['audio'], 'speech.flac', { type: 'audio/flac' });
+    const audio = document.createElement('audio');
+    vi.spyOn(audio, 'load').mockImplementation(() => undefined);
+    defineNumber(audio, 'duration', 12.5);
+
+    const resultPromise = inspectBrowserMediaMetadata(file, 'blob:speech', {
+      createMediaElement: (kind) => {
+        expect(kind).toBe('audio');
+        return audio;
+      },
+    });
+    audio.dispatchEvent(new Event('loadedmetadata'));
+
+    await expect(resultPromise).resolves.toMatchObject({
+      source: 'browser',
+      kind: 'audio',
+      durationSeconds: 12.5,
+      hasAudio: true,
+      hasVideo: false,
+    });
+  });
+
+  it('keeps a video-container player viable when dimensions and audio hints are absent', async () => {
+    const file = new File(['audio-only'], 'audio-only.mp4', {
+      type: 'video/mp4',
+    });
+    const video = document.createElement('video');
+    vi.spyOn(video, 'load').mockImplementation(() => undefined);
+    defineNumber(video, 'duration', 8);
+    defineNumber(video, 'videoWidth', 0);
+    defineNumber(video, 'videoHeight', 0);
+    Object.defineProperty(video, 'audioTracks', {
+      configurable: true,
+      value: undefined,
+    });
+
+    const resultPromise = inspectBrowserMediaMetadata(file, 'blob:audio-only', {
+      createMediaElement: () => video,
+    });
+    video.dispatchEvent(new Event('loadedmetadata'));
+
+    await expect(resultPromise).resolves.toMatchObject({
+      kind: 'video',
+      durationSeconds: 8,
+      hasVideo: undefined,
+      hasAudio: undefined,
+    });
+  });
+
+  it('reports load errors without revoking the caller-owned object URL', async () => {
+    const revokeObjectUrl = vi.spyOn(URL, 'revokeObjectURL');
+    const video = document.createElement('video');
+    vi.spyOn(video, 'load').mockImplementation(() => undefined);
+    const resultPromise = inspectBrowserMediaMetadata(
+      new File([], 'broken.mp4', { type: 'video/mp4' }),
+      'blob:broken',
+      { createMediaElement: () => video }
+    );
+
+    video.dispatchEvent(new Event('error'));
+
+    await expect(resultPromise).rejects.toMatchObject({
+      name: 'BrowserMetadataError',
+      code: 'load-error',
+    });
+    expect(revokeObjectUrl).not.toHaveBeenCalled();
+  });
+
+  it('supports cancellation and a bounded metadata timeout', async () => {
+    const file = new File([], 'long.mp4', { type: 'video/mp4' });
+    const controller = new AbortController();
+    const firstVideo = document.createElement('video');
+    vi.spyOn(firstVideo, 'load').mockImplementation(() => undefined);
+    const cancelled = inspectBrowserMediaMetadata(file, 'blob:cancel', {
+      createMediaElement: () => firstVideo,
+      signal: controller.signal,
+    });
+    controller.abort();
+
+    await expect(cancelled).rejects.toMatchObject({
+      code: 'aborted',
+    });
+
+    vi.useFakeTimers();
+    const secondVideo = document.createElement('video');
+    vi.spyOn(secondVideo, 'load').mockImplementation(() => undefined);
+    const timedOut = inspectBrowserMediaMetadata(file, 'blob:timeout', {
+      createMediaElement: () => secondVideo,
+      timeoutMilliseconds: 25,
+    });
+    const timeoutExpectation = expect(timedOut).rejects.toEqual(
+      new BrowserMetadataError(
+        'timeout',
+        'Browser metadata loading exceeded 1 seconds.'
+      )
+    );
+    await vi.advanceTimersByTimeAsync(25);
+    await timeoutExpectation;
+  });
+});
+
+function defineNumber(
+  target: HTMLMediaElement,
+  property: 'duration' | 'videoHeight' | 'videoWidth',
+  value: number
+): void {
+  Object.defineProperty(target, property, {
+    configurable: true,
+    value,
+  });
+}
--- a/tests/unit/release-package.test.mjs
+++ b/tests/unit/release-package.test.mjs
@@ -165,30 +165,30 @@ describe('licence release gate', () => {
 describe('release checksum', () => {
  it('formats and parses the portable sidecar form', () => {
    const digest = 'a'.repeat(64);
-    const line = checksumLine(digest, 'av-tools-0.2.1.zip');
-    expect(line).toBe(`${digest}  av-tools-0.2.1.zip\n`);
+    const line = checksumLine(digest, 'av-tools-0.3.0.zip');
+    expect(line).toBe(`${digest}  av-tools-0.3.0.zip\n`);
    expect(parseChecksumLine(line)).toEqual({
-      archiveName: 'av-tools-0.2.1.zip',
+      archiveName: 'av-tools-0.3.0.zip',
      digest,
    });
  });

  it('writes and verifies a checksum sidecar', async () => {
    const directory = await temporaryDirectory();
-    const archive = path.join(directory, 'av-tools-0.2.1.zip');
+    const archive = path.join(directory, 'av-tools-0.3.0.zip');
    await writeFile(archive, 'deterministic bytes');
    const result = await writeChecksum(archive);
    expect(await verifyChecksum(archive, result.sidecarPath)).toBe(
      result.digest
    );
    expect(await readFile(result.sidecarPath, 'utf8')).toContain(
-      '  av-tools-0.2.1.zip'
+      '  av-tools-0.3.0.zip'
    );
  });

  it('rejects checksum mismatches', async () => {
    const directory = await temporaryDirectory();
-    const archive = path.join(directory, 'av-tools-0.2.1.zip');
+    const archive = path.join(directory, 'av-tools-0.3.0.zip');
    const sidecar = `${archive}.sha256`;
    await writeFile(archive, 'changed');
    await mkdir(path.dirname(sidecar), { recursive: true });
Author	SHA1	Message	Date
Albrecht Degering	597ea044b6	chore: prepare av-tools 0.3.0 release	2026-07-27 18:38:20 +02:00
Albrecht Degering	f2c0fc12d2	feat: make media inspection progressive	2026-07-27 18:25:47 +02:00