fix(subtitles): validate tools before local generation

- Detect PATH tools and report missing executable settings
- Check output directories before model downloads or audio extraction

launcher/commands/generate-subtitles-command.test.ts

@@ -32,6 +32,12 @@ function fixture(argv: string[] = ['generate-subs', '/media/episode.mkv']) {
     readConfig: () => ({ subtitleGeneration: { modelPath: '/models/external.bin' } }),
     configPath: () => '/settings/SubMiner/config.jsonc',
     resolveModel: async () => ({ kind: 'external', path: '/models/external.bin' }),
+    resolveTools: async () => ({
+      ffmpeg: { kind: 'found', path: '/usr/bin/ffmpeg' },
+      ffprobe: { kind: 'found', path: '/usr/bin/ffprobe' },
+      whisper: { kind: 'found', path: '/usr/bin/whisper-cli' },
+      vad: null,
+    }),
     downloadModel: async () => {
       throw new Error('Unexpected model download');
     },
@@ -92,6 +98,22 @@ test('launcher uses the shared core and selected mpv audio then loads the genera
   assert.equal(f.detached(), true);
 });
 
+test('launcher reports a missing executable before downloading a model', async () => {
+  const f = fixture(['generate-subs', '/media/episode.mkv', '--download-model']);
+  f.deps.resolveModel = async () => ({ kind: 'missing', path: '/models/missing.bin' });
+  f.deps.resolveTools = async () => ({
+    ffmpeg: { kind: 'found', path: '/usr/bin/ffmpeg' },
+    ffprobe: { kind: 'found', path: '/usr/bin/ffprobe' },
+    whisper: { kind: 'missing', message: 'whisper-cli was not found on PATH.' },
+    vad: null,
+  });
+  await assert.rejects(
+    runGenerateSubtitlesCommand(f.context, f.deps),
+    /whisper-cli was not found on PATH/,
+  );
+  assert.equal(f.generations.length, 0);
+});
+
 test('launcher never downloads a model without the explicit option', async () => {
   const f = fixture();
   f.deps.resolveModel = async () => ({ kind: 'missing', path: '/models/missing.bin' });

launcher/commands/generate-subtitles-command.ts

@@ -5,7 +5,9 @@ import {
   downloadSubtitleGenerationModel,
   generateJapaneseSubtitles,
   resolveSubtitleGenerationModel,
+  resolveSubtitleGenerationTools,
 } from '../../src/core/services/subtitle-generation.js';
+import { requireSubtitleGenerationTools } from '../../src/core/services/subtitle-generation-tools.js';
 import {
   resolveSubtitleGenerationConfig,
   type SubtitleGenerationProgress,
@@ -26,6 +28,7 @@ interface GenerationCommandDeps {
   readConfig: typeof readLauncherMainConfigObject;
   configPath: typeof resolveLauncherMainConfigPath;
   resolveModel: typeof resolveSubtitleGenerationModel;
+  resolveTools: typeof resolveSubtitleGenerationTools;
   downloadModel: typeof downloadSubtitleGenerationModel;
   generate: typeof generateJapaneseSubtitles;
   mpvCommand: typeof sendMpvCommandWithResponse;
@@ -36,6 +39,7 @@ const defaultDeps: GenerationCommandDeps = {
   readConfig: readLauncherMainConfigObject,
   configPath: resolveLauncherMainConfigPath,
   resolveModel: resolveSubtitleGenerationModel,
+  resolveTools: resolveSubtitleGenerationTools,
   downloadModel: downloadSubtitleGenerationModel,
   generate: generateJapaneseSubtitles,
   mpvCommand: sendMpvCommandWithResponse,
@@ -162,6 +166,8 @@ export async function runGenerateSubtitlesCommand(
         ? await readMpvAudioStream(context.mpvSocketPath, deps.mpvCommand)
         : undefined);
     const onProgress = createGenerationProgressReporter(write);
+    // Missing executables fail here, before any model download starts.
+    requireSubtitleGenerationTools(await deps.resolveTools(config));
     const model = await deps.resolveModel(config, modelDirectory);
     if (model.kind === 'invalid') throw new Error(model.message);
     if (model.kind === 'missing') {