Add centralized pipeline fallback notifier

src/ai/user-request-pipeline/fallback-notifier.ts

@@ -0,0 +1,38 @@
+import type {Message} from "typescript-telegram-bot-api";
+import {replyToMessage, logError} from "../../util/utils.js";
+import type {PipelineFallbackDecision} from "./fallback-executor.js";
+import {PipelineFallbackNotificationRegistry} from "./fallback-notifier-registry.js";
+import {resolvePipelineFallbackText} from "./fallback-notifier-text.js";
+
+export class PipelineFallbackNotifier {
+    private readonly registry = new PipelineFallbackNotificationRegistry();
+
+    constructor(
+        private readonly sourceMessage: Message,
+        private readonly sendFallbackMessage: (text: string) => Promise<void> = async text => {
+            await replyToMessage({
+                message: this.sourceMessage,
+                text,
+            });
+        },
+    ) {}
+
+    async notify(requestId: string, decision: PipelineFallbackDecision): Promise<{notified: boolean; text?: string}> {
+        if (!this.registry.claim(requestId, decision)) {
+            return {notified: false};
+        }
+
+        const text = resolvePipelineFallbackText(decision.stage, decision.action);
+        if (!text) {
+            return {notified: false};
+        }
+
+        try {
+            await this.sendFallbackMessage(text);
+            return {notified: true, text};
+        } catch (error) {
+            logError(error instanceof Error ? error : String(error));
+            return {notified: false, text};
+        }
+    }
+}