feat: add edge tts fallback provider

src/config/types.tts.ts

@@ -1,4 +1,4 @@
-export type TtsProvider = "elevenlabs" | "openai";
+export type TtsProvider = "elevenlabs" | "openai" | "edge";
 
 export type TtsMode = "final" | "all";
 
@@ -55,6 +55,20 @@ export type TtsConfig = {
     model?: string;
     voice?: string;
   };
+  /** Microsoft Edge (node-edge-tts) configuration. */
+  edge?: {
+    /** Explicitly allow Edge TTS usage (no API key required). */
+    enabled?: boolean;
+    voice?: string;
+    lang?: string;
+    outputFormat?: string;
+    pitch?: string;
+    rate?: string;
+    volume?: string;
+    saveSubtitles?: boolean;
+    proxy?: string;
+    timeoutMs?: number;
+  };
   /** Optional path for local TTS user preferences JSON. */
   prefsPath?: string;
   /** Hard cap for text sent to TTS (chars). */

src/config/zod-schema.core.ts

@@ -156,7 +156,7 @@ export const MarkdownConfigSchema = z
   .strict()
   .optional();
 
-export const TtsProviderSchema = z.enum(["elevenlabs", "openai"]);
+export const TtsProviderSchema = z.enum(["elevenlabs", "openai", "edge"]);
 export const TtsModeSchema = z.enum(["final", "all"]);
 export const TtsConfigSchema = z
   .object({
@@ -207,6 +207,21 @@ export const TtsConfigSchema = z
       })
       .strict()
       .optional(),
+    edge: z
+      .object({
+        enabled: z.boolean().optional(),
+        voice: z.string().optional(),
+        lang: z.string().optional(),
+        outputFormat: z.string().optional(),
+        pitch: z.string().optional(),
+        rate: z.string().optional(),
+        volume: z.string().optional(),
+        saveSubtitles: z.boolean().optional(),
+        proxy: z.string().optional(),
+        timeoutMs: z.number().int().min(1000).max(120000).optional(),
+      })
+      .strict()
+      .optional(),
     prefsPath: z.string().optional(),
     maxTextLength: z.number().int().min(1).optional(),
     timeoutMs: z.number().int().min(1000).max(120000).optional(),