fix(stalker): restore playback command compatibility

.changes/stalker-playback-command-paths.md

@@ -0,0 +1,6 @@
+---
+type: fix
+area: stalker
+---
+
+Stalker movies, series, live TV, and radio now start correctly when portals return empty compatibility error fields or require literal `/` separators in playback commands.

apps/electron-backend/src/app/services/stalker-session/stalker-http-session.spec.ts

@@ -96,6 +96,36 @@ describe('StalkerHttpSession', () => {
         expect(config.headers).not.toHaveProperty('Authorization');
         expect(config.headers).not.toHaveProperty('Cookie');
         expect(config.headers).not.toHaveProperty('Proxy-Authorization');
+        expect(config.paramsSerializer).toBeUndefined();
+    });
+
+    it('preserves only cmd slashes while encoding reserved query characters', async () => {
+        axiosMock.mockResolvedValueOnce({
+            data: Buffer.from('{}'),
+            headers: {},
+            status: 200,
+        });
+        const session = new StalkerHttpSession(
+            new StalkerCookieJar(),
+            DEFAULT_TRANSPORT
+        );
+
+        await session.request({
+            mode: STALKER_HTTP_REQUEST_MODES.Anonymous,
+            params: {
+                type: 'vod',
+                action: 'create_link',
+                cmd: '/media/file 4?quality=hd&label=x=y#preview.mpg',
+                search: '/catalog value&mode=all#anchor',
+                page: 2,
+            },
+            url: 'http://192.168.1.20/server/load.php',
+        });
+
+        const config = axiosMock.mock.calls[0][0];
+        expect(axios.getUri(config)).toBe(
+            'http://192.168.1.20/server/load.php?type=vod&action=create_link&cmd=/media/file%204%3Fquality%3Dhd%26label%3Dx%3Dy%23preview.mpg&search=%2Fcatalog%20value%26mode%3Dall%23anchor&page=2'
+        );
     });
 
     it('blocks an anonymous public-to-private redirect before target contact', async () => {

apps/electron-backend/src/app/services/stalker-session/stalker-http-session.ts

@@ -118,6 +118,11 @@ export class StalkerHttpSession {
                         request.params === undefined
                             ? undefined
                             : { ...request.params },
+                    paramsSerializer: hasOwnCommandParameter(request.params)
+                        ? {
+                              serialize: serializeStalkerHttpParameters,
+                          }
+                        : undefined,
                     redirectHooks: {
                         beforeValidatedRedirect: (redirect) => {
                             validateRedirectTarget(
@@ -194,6 +199,30 @@ export class StalkerHttpSession {
     }
 }
 
+function serializeStalkerHttpParameters(
+    parameters: StalkerHttpParameters
+): string {
+    return Object.entries(parameters)
+        .map(([key, value]) => {
+            const encodedValue = encodeURIComponent(String(value));
+            const compatibleValue =
+                key === 'cmd'
+                    ? encodedValue.replace(/%2F/gi, '/')
+                    : encodedValue;
+            return `${encodeURIComponent(key)}=${compatibleValue}`;
+        })
+        .join('&');
+}
+
+function hasOwnCommandParameter(
+    parameters: StalkerHttpParameters | undefined
+): boolean {
+    return (
+        parameters !== undefined &&
+        Object.prototype.hasOwnProperty.call(parameters, 'cmd')
+    );
+}
+
 function assertTransportConfig(config: StalkerTransportConfig): void {
     if (
         !isPositiveFiniteBound(

apps/stalker-mock-server/fixtures/replay/e2e/full-session-catalog-playback.json

@@ -673,7 +673,10 @@
                             "kind": "json",
                             "value": {
                                 "js": {
-                                    "cmd": "/stream/ready.m3u8"
+                                    "cmd": "/stream/ready.m3u8",
+                                    "error": "",
+                                    "load": "",
+                                    "streamer_id": "1"
                                 }
                             }
                         },

docs/architecture/stalker-portal.md

@@ -65,6 +65,12 @@ Stalker has two deliberately separate request paths:
    `STALKER_REQUEST`/HTTP adapter. They do not acquire a main-owned full
    session.
 
+Stalker query serialization is a compatibility contract: `cmd` values retain
+literal forward slashes while query separators and all other parameter data
+remain percent-encoded. Do not replace this behavior with Axios default
+parameter serialization; some Ministra portals inspect the raw `create_link`
+query and reject encoded playback-path separators.
+
 The primary ownership points are:
 
 - pure URL, response, identity, state-machine, and request-policy rules:
@@ -134,6 +140,11 @@ type remains fail-closed for ordinary candidates; only a persisted learned
 endpoint may treat a body rejected solely by media type as a stale-hint miss
 and continue bounded discovery.
 
+Some successful Stalker responses, including `create_link`, carry an exact
+empty `error` string alongside their payload. The response classifier treats
+that compatibility sentinel as no error; non-empty error strings and all other
+error indicators remain fail-closed.
+
 Persisted compatibility fields are:
 
 - `stalkerSourceUrl`

libs/portal/stalker/protocol/src/lib/stalker-response-classifier.spec.ts

@@ -242,6 +242,21 @@ describe('Stalker response classifier', () => {
         ).toEqual({ kind: 'none' });
     });
 
+    it('accepts the empty error field returned by successful create_link responses', () => {
+        expect(
+            classifyStalkerResponseFailure({
+                httpStatus: 200,
+                value: {
+                    js: {
+                        cmd: 'ffmpeg http://media.invalid/movie.ts',
+                        error: '',
+                        load: '',
+                    },
+                },
+            })
+        ).toEqual({ kind: 'none' });
+    });
+
     it.each([
         ['Authorization failed', { kind: 'token-rejected' }],
         ['Access denied', { kind: 'failure', reason: 'account-access-denied' }],

libs/portal/stalker/protocol/src/lib/stalker-response-classifier.ts

@@ -344,11 +344,13 @@ function extractBodyError(
 ): string | undefined {
     const envelope = asRecord(value);
     const js = asRecord(envelope?.['js']);
-    if (typeof js?.['error'] === 'string') {
-        return js['error'];
+    const jsError = js?.['error'];
+    if (typeof jsError === 'string' && jsError !== '') {
+        return jsError;
     }
-    if (typeof envelope?.['error'] === 'string') {
-        return envelope['error'];
+    const envelopeError = envelope?.['error'];
+    if (typeof envelopeError === 'string' && envelopeError !== '') {
+        return envelopeError;
     }
     if (value !== undefined) {
         return undefined;