diff --git a/docs/architecture/embedded-inline-playback.md b/docs/architecture/embedded-inline-playback.md
index 6dbb15a33..0348653e0 100644
--- a/docs/architecture/embedded-inline-playback.md
+++ b/docs/architecture/embedded-inline-playback.md
@@ -264,6 +264,13 @@ The diagnostic surface covers the inline player viewport when playback fails, wi
 
 URL extension metadata is filtered before diagnostics and player selection use it. Web script extensions such as `.php` are not shown as stream containers; explicit media query metadata such as `extension=ts` or `format=m3u8` is preferred when present.
 
+MKV sources are attempted through Chromium's native Matroska path. Video.js
+receives `video/matroska` for `.mkv` URLs and explicit query metadata such as
+`extension=mkv` or `container=mkv`; ArtPlayer and HTML5 continue to use their
+native video paths. This is container support rather than a universal codec
+guarantee: native source or decode failures still produce the existing
+diagnostic and explicit MPV/VLC fallback.
+
 Portal VOD and episode payloads with `contentInfo` are treated as non-live by the inline players unless `isLive` is explicitly set. If Chromium leaves the underlying MediaSource duration at `Infinity` for a finite TS VOD, the Video.js wrapper normalizes its UI duration from the finite `seekable` or `buffered` range. Embedded MPV uses the same live decision rule and shows an unknown duration placeholder for VOD/episode snapshots until MPV reports a finite duration. This removes the misleading `LIVE` control state without changing stream decoding, diagnostics, or external fallback behavior.
 
 When a diagnostic is actionable in Electron, the diagnostic surface may offer `Open in MPV`, `Open in VLC`, `Copy URL`, technical details, and `Retry`. Web builds only expose copy/help text and retry. MPV/VLC fallback requests carry the original `ResolvedPortalPlayback` payload so headers, referer, origin, user-agent, content metadata, and resume offset stay intact. Retry clears the current diagnostic and rebuilds the active inline player inputs; it does not change the saved player setting.
diff --git a/docs/superpowers/plans/2026-07-19-mkv-inline-playback.md b/docs/superpowers/plans/2026-07-19-mkv-inline-playback.md
new file mode 100644
index 000000000..25c60b643
--- /dev/null
+++ b/docs/superpowers/plans/2026-07-19-mkv-inline-playback.md
@@ -0,0 +1,342 @@
+# Native Matroska Inline Playback Implementation Plan
+
+> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.
+
+**Goal:** Let the Video.js inline player attempt MKV playback through Chromium's native Matroska pipeline while preserving codec-dependent diagnostics and external-player fallback.
+
+**Architecture:** Keep `WebPlayerViewComponent` as the single Video.js source-type router and keep `getPlaybackMediaExtensionFromUrl()` as the canonical parser for path and query metadata. Add only an explicit MKV MIME branch; ArtPlayer and HTML5 remain on their existing native-video paths, and native playback errors remain authoritative.
+
+**Tech Stack:** Angular 21, TypeScript, Jest/Nx, Electron 41/Chromium 146, agent-browser CDP
+
+---
+
+## Task 1: Add failing Video.js MIME regression tests
+
+**Files:**
+
+- Modify: `libs/ui/playback/src/lib/web-player-view/web-player-view.component.spec.ts`
+- Test: `libs/ui/playback/src/lib/web-player-view/web-player-view.component.spec.ts`
+
+- [x] **Step 1: Add a path-extension regression test**
+
+Add this test beside the existing query-declared HLS test:
+
+```ts
+it('uses the Matroska mime type for MKV paths', () => {
+    const streamUrl = 'https://example.com/archive/movie.mkv';
+
+    component.setVjsOptions(streamUrl);
+
+    expect(component.vjsOptions.sources).toEqual([
+        {
+            src: streamUrl,
+            type: 'video/matroska',
+        },
+    ]);
+});
+```
+
+- [x] **Step 2: Add a query-metadata regression test**
+
+```ts
+it('uses the Matroska mime type for query-declared MKV streams', () => {
+    const streamUrl =
+        'https://example.com/play?container=mkv&token=signed';
+
+    component.setVjsOptions(streamUrl);
+
+    expect(component.vjsOptions.sources).toEqual([
+        {
+            src: streamUrl,
+            type: 'video/matroska',
+        },
+    ]);
+});
+```
+
+- [x] **Step 3: Run the focused spec and verify RED**
+
+Run:
+
+```bash
+pnpm nx test ui-playback --skip-nx-cache --runInBand --runTestsByPath libs/ui/playback/src/lib/web-player-view/web-player-view.component.spec.ts
+```
+
+Expected: the two new expectations fail because the actual source type is still `video/mp4`; existing tests continue to pass.
+
+## Task 2: Route MKV sources as Matroska
+
+**Files:**
+
+- Modify: `libs/ui/playback/src/lib/web-player-view/web-player-view.component.ts`
+- Test: `libs/ui/playback/src/lib/web-player-view/web-player-view.component.spec.ts`
+
+- [x] **Step 1: Add the smallest production change**
+
+Change the MIME decision to:
+
+```ts
+const mimeType =
+    extension === 'm3u' || extension === 'm3u8'
+        ? 'application/x-mpegURL'
+        : extension === 'ts' || !extension
+          ? 'video/mp2t'
+          : extension === 'mkv'
+            ? 'video/matroska'
+            : 'video/mp4';
+```
+
+Do not add `canPlayType()` preflight or a codec list: the actual native load result remains authoritative.
+
+- [x] **Step 2: Run the focused spec and verify GREEN**
+
+Run:
+
+```bash
+pnpm nx test ui-playback --skip-nx-cache --runInBand --runTestsByPath libs/ui/playback/src/lib/web-player-view/web-player-view.component.spec.ts
+```
+
+Expected: all tests in the spec pass.
+
+- [x] **Step 3: Run the complete affected unit-test target**
+
+Run:
+
+```bash
+pnpm nx test ui-playback --skip-nx-cache --runInBand
+```
+
+Expected: PASS.
+
+## Task 3: Document the native MKV contract
+
+**Files:**
+
+- Modify: `docs/architecture/embedded-inline-playback.md`
+
+- [x] **Step 1: Extend the codec/container diagnostics section**
+
+After the URL extension metadata paragraph, document:
+
+```md
+MKV sources are attempted through Chromium's native Matroska path. Video.js
+receives `video/matroska` for `.mkv` URLs and explicit query metadata such as
+`extension=mkv` or `container=mkv`; ArtPlayer and HTML5 continue to use their
+native video paths. This is container support rather than a universal codec
+guarantee: native source/decode failures still produce the existing diagnostic
+and explicit MPV/VLC fallback.
+```
+
+- [x] **Step 2: Verify Markdown and whitespace**
+
+Run:
+
+```bash
+git diff --check
+git diff -- docs/architecture/embedded-inline-playback.md
+```
+
+Expected: no whitespace errors; the diff describes only the new MKV contract.
+
+## Task 4: Verify the Electron runtime with a supported MKV
+
+**Files:**
+
+- Temporary fixture only: `/tmp/iptvnator-mkv-inline-playback/video.mkv`
+- No committed binary fixture
+
+- [x] **Step 1: Download a small H.264/AAC Matroska fixture**
+
+Run:
+
+```bash
+mkdir -p /tmp/iptvnator-mkv-inline-playback
+curl --fail --location https://remotion.media/video.mkv --output /tmp/iptvnator-mkv-inline-playback/video.mkv
+```
+
+Record the downloaded SHA-256 in the verification notes:
+
+```bash
+shasum -a 256 /tmp/iptvnator-mkv-inline-playback/video.mkv
+```
+
+- [x] **Step 2: Start an isolated IPTVnator Electron runtime**
+
+If the standard IPTVnator development ports are free, run in a long-lived
+terminal:
+
+```bash
+IPTVNATOR_TRACE_RENDERER_CONSOLE=1 pnpm nx serve electron-backend
+```
+
+Wait for the IPTVnator renderer target on `127.0.0.1:9222`. If another
+worktree already owns the development ports, do not stop it; instead launch
+the repository's Electron 41 binary with a temporary BrowserWindow harness on
+an unused CDP port and remove the harness after the smoke.
+
+- [x] **Step 3: Exercise Chromium's native Matroska pipeline in an Electron renderer**
+
+Use the repository's documented Electron CDP workflow and `agent-browser` to
+attach to the IPTVnator page. In the renderer:
+
+1. Read `/tmp/iptvnator-mkv-inline-playback/video.mkv` through a temporary
+   localhost range server that returns `Content-Type: video/matroska`.
+2. Create a temporary `<video muted autoplay>` smoke element using that URL.
+3. Wait for `loadedmetadata`.
+4. Assert `videoWidth > 0`, `duration > 0`, and `currentTime` advances.
+5. Remove the temporary element and stop the server.
+
+This is a runtime capability check, while the focused component tests prove
+that the Video.js application path supplies the same `video/matroska` MIME.
+
+- [x] **Step 4: Reconfirm unsupported-MKV fallback coverage**
+
+Run the existing WebPlayerView spec containing the synthetic native MKV error:
+
+```bash
+pnpm nx test ui-playback --skip-nx-cache --runInBand --runTestsByPath libs/ui/playback/src/lib/web-player-view/web-player-view.component.spec.ts
+```
+
+Expected: PASS, including the existing MKV diagnostic and MPV fallback
+assertions.
+
+## Task 5: Run final validation
+
+**Files:**
+
+- Verify only
+
+- [x] **Step 1: Verify workspace discovery**
+
+Run:
+
+```bash
+pnpm nx show projects
+```
+
+Expected: projects are discovered successfully.
+
+- [x] **Step 2: Run affected lint**
+
+Run:
+
+```bash
+pnpm nx lint ui-playback --skip-nx-cache
+```
+
+Expected: PASS.
+
+- [x] **Step 3: Run web type checking**
+
+Run:
+
+```bash
+pnpm run typecheck:web
+```
+
+Expected: PASS.
+
+- [x] **Step 4: Inspect the complete change**
+
+Run:
+
+```bash
+git diff --check
+git diff --stat origin/master...HEAD
+git status --short
+```
+
+Expected: no whitespace errors and only the design, plan, implementation,
+regression tests, and canonical playback documentation are in scope.
+
+## Task 6: Perform local Codex review and address findings
+
+**Files:**
+
+- Review all branch changes against `origin/master`
+
+- [x] **Step 1: Commit the implementation checkpoint**
+
+Stage only the MKV plan, implementation, tests, and documentation, then commit:
+
+```bash
+git add docs/superpowers/plans/2026-07-19-mkv-inline-playback.md \
+  docs/architecture/embedded-inline-playback.md \
+  libs/ui/playback/src/lib/web-player-view/web-player-view.component.ts \
+  libs/ui/playback/src/lib/web-player-view/web-player-view.component.spec.ts
+git commit -m "fix(playback): route MKV sources as Matroska"
+```
+
+- [x] **Step 2: Run local Codex code review**
+
+Run:
+
+```bash
+codex review --base origin/master
+```
+
+Classify every finding by severity and verify it against the code. Fix all
+confirmed correctness, regression, security, or maintainability findings before
+publication. Re-run the targeted tests, lint, type check, and review after any
+material correction.
+
+- [x] **Step 3: Confirm a clean, reviewed branch**
+
+Run:
+
+```bash
+git status --short
+git log --oneline --decorate origin/master..HEAD
+```
+
+Expected: clean worktree and a focused two-commit branch (design plus
+implementation), unless the review required a clearly named follow-up commit.
+
+## Task 7: Push and open the pull request
+
+**Files:**
+
+- GitHub branch and PR metadata only
+
+- [ ] **Step 1: Confirm GitHub authentication**
+
+Run:
+
+```bash
+gh auth status
+```
+
+- [ ] **Step 2: Push the reviewed branch**
+
+Run:
+
+```bash
+git push --set-upstream origin agent/mkv-inline-playback
+```
+
+- [ ] **Step 3: Open a focused draft PR**
+
+Create a draft PR targeting `master` with title:
+
+```text
+fix(playback): route MKV sources as Matroska
+```
+
+The body must summarize:
+
+- Video.js now sends `.mkv` and query-declared MKV as `video/matroska`;
+- ArtPlayer/HTML5 behavior and error-driven fallback are unchanged;
+- codec support remains Chromium/platform-dependent;
+- automated test, lint, type-check, Electron smoke, and local Codex review
+  results;
+- the temporary runtime fixture URL and SHA-256.
+
+- [ ] **Step 4: Verify the published PR**
+
+Run:
+
+```bash
+gh pr view --json number,title,url,isDraft,baseRefName,headRefName,state
+```
+
+Expected: an OPEN draft PR from `agent/mkv-inline-playback` into `master`.
diff --git a/libs/ui/playback/src/lib/web-player-view/web-player-view.component.spec.ts b/libs/ui/playback/src/lib/web-player-view/web-player-view.component.spec.ts
index 42cc4d5d6..444cdf566 100644
--- a/libs/ui/playback/src/lib/web-player-view/web-player-view.component.spec.ts
+++ b/libs/ui/playback/src/lib/web-player-view/web-player-view.component.spec.ts
@@ -219,6 +219,33 @@ describe('WebPlayerViewComponent', () => {
         ]);
     });
 
+    it('uses the Matroska mime type for MKV paths', () => {
+        const streamUrl = 'https://example.com/archive/movie.mkv';
+
+        component.setVjsOptions(streamUrl);
+
+        expect(component.vjsOptions.sources).toEqual([
+            {
+                src: streamUrl,
+                type: 'video/matroska',
+            },
+        ]);
+    });
+
+    it('uses the Matroska mime type for query-declared MKV streams', () => {
+        const streamUrl =
+            'https://example.com/play?container=mkv&token=signed';
+
+        component.setVjsOptions(streamUrl);
+
+        expect(component.vjsOptions.sources).toEqual([
+            {
+                src: streamUrl,
+                type: 'video/matroska',
+            },
+        ]);
+    });
+
     it('treats web script playback URLs without declared media extension as MPEG-TS', () => {
         const streamUrl = 'https://example.com/live.php?stream=123&token=x';
 
diff --git a/libs/ui/playback/src/lib/web-player-view/web-player-view.component.ts b/libs/ui/playback/src/lib/web-player-view/web-player-view.component.ts
index fbab90b9e..3c629e4b3 100644
--- a/libs/ui/playback/src/lib/web-player-view/web-player-view.component.ts
+++ b/libs/ui/playback/src/lib/web-player-view/web-player-view.component.ts
@@ -180,7 +180,7 @@ export class WebPlayerViewComponent {
                 ? 'application/x-mpegURL'
                 : extension === 'ts' || !extension
                   ? 'video/mp2t'
-                  : 'video/mp4';
+                  : extension === 'mkv' ? 'video/matroska' : 'video/mp4';
 
         this.vjsOptions = {
             isLive,