[Improve] Surface routing failures instead of silently showing the picker

apps/api/src/handlers/slack/events/auto-route-fallback.ts

@@ -1,6 +1,7 @@
 import type { SlackInstallation, SlackUserMapping } from '@roomote/db/server';
 import {
   showTaskConfiguration,
+  SLACK_ROUTING_UNAVAILABLE_NOTICE,
   type SlackEvent,
   type SlackNotifier,
   type StartAutoRoutedSlackTaskResult,
@@ -54,6 +55,10 @@ export async function showManualPickerForAutoRouteFallback(params: {
       : {}),
   };
 
+  const routingFailedFromException =
+    params.result.status === 'not_started' &&
+    params.result.routingFallback?.cause === 'exception';
+
   await showTaskConfiguration({
     event,
     slackInstallation: params.slackInstallation as SlackInstallation,
@@ -62,6 +67,9 @@ export async function showManualPickerForAutoRouteFallback(params: {
     skipRouting: true,
     skipMcpSetupSuggestion: true,
     processingReactionName: params.processingReactionName,
+    ...(routingFailedFromException
+      ? { routingFailureNoticeText: SLACK_ROUTING_UNAVAILABLE_NOTICE }
+      : {}),
   });
 
   return true;

packages/cloud-agents/src/server/router/index.ts

@@ -20,6 +20,7 @@ export type {
   RoutingResult,
   PlatformAnswerResult,
   RoutingDecision,
+  RoutingFallbackCause,
   FollowUpIntent,
   FollowUpClassification,
 } from './types';

packages/cloud-agents/src/server/router/router-service.ts

@@ -362,6 +362,7 @@ async function runRoutingDecision(
           decision: {
             status: 'fallback',
             reason: built.fallbackReason,
+            cause: 'model_decision',
           },
           phase: responseResult.phase ?? 'fallback',
           model: routingModel,
@@ -408,6 +409,7 @@ async function runRoutingDecision(
         status: 'fallback',
         reason:
           error instanceof Error ? error.message : 'Unknown routing error',
+        cause: 'exception',
       },
       phase: 'fallback',
       model: routingModel,
@@ -499,6 +501,7 @@ export async function routeTask(
       status: 'fallback',
       reason:
         'Meta question answer was unavailable, and normal routing could not be resolved.',
+      cause: 'model_decision',
     };
     fallbackDecision.debug = {
       phase: 'fallback',
@@ -513,6 +516,7 @@ export async function routeTask(
         sourceType: context.source.type,
         model,
         phase: 'fallback',
+        cause: fallbackDecision.cause,
         toolsUsed,
         needsExternalLookup,
         confidence: null,
@@ -566,6 +570,7 @@ export async function routeTask(
           sourceType: context.source.type,
           model,
           phase,
+          cause: decision.cause ?? 'model_decision',
           toolsUsed,
           needsExternalLookup,
           confidence: null,
@@ -588,6 +593,7 @@ export async function routeGitHubTask(
     return {
       status: 'fallback',
       reason: 'routeGitHubTask requires a GitHub routing context.',
+      cause: 'exception',
     };
   }
 
@@ -647,6 +653,7 @@ export async function routeGitHubTask(
         sourceType: context.source.type,
         model: routingModel,
         phase: 'fallback',
+        cause: 'exception',
         toolsUsed: [],
         needsExternalLookup: null,
         confidence: null,
@@ -658,6 +665,7 @@ export async function routeGitHubTask(
     return {
       status: 'fallback',
       reason,
+      cause: 'exception',
       debug: {
         phase: 'fallback',
         toolsUsed: [],

packages/cloud-agents/src/server/router/types.ts

@@ -220,10 +220,24 @@ export interface PlatformAnswerResult {
   debug?: RoutingDebugInfo;
 }
 
+/**
+ * Why a routing attempt ended in fallback. `model_decision` means the router
+ * ran but declined to pick (ambiguous request, unmapped workspace);
+ * `exception` means the routing infrastructure itself failed (provider error,
+ * timeout) and surfaces should tell the user routing is unavailable rather
+ * than silently showing the manual picker. Absent means `model_decision`.
+ */
+export type RoutingFallbackCause = 'exception' | 'model_decision';
+
 export type RoutingDecision =
   | { status: 'routed'; result: RoutingResult }
   | { status: 'platform_answer'; result: PlatformAnswerResult }
-  | { status: 'fallback'; reason: string; debug?: RoutingDebugInfo };
+  | {
+      status: 'fallback';
+      reason: string;
+      cause?: RoutingFallbackCause;
+      debug?: RoutingDebugInfo;
+    };
 
 export interface GitHubRoutingResult {
   reasoning: string;
@@ -233,7 +247,12 @@ export interface GitHubRoutingResult {
 
 export type GitHubRoutingDecision =
   | { status: 'routed'; result: GitHubRoutingResult }
-  | { status: 'fallback'; reason: string; debug?: RoutingDebugInfo };
+  | {
+      status: 'fallback';
+      reason: string;
+      cause?: RoutingFallbackCause;
+      debug?: RoutingDebugInfo;
+    };
 
 export interface WorkspaceResponse {
   workspaceValue: string;