refactor(catalog): remove .ts import extensions, as any casts, and normalize alias resolution

Addresses code review feedback from PR #2136:

- Remove .ts extensions from @omniroute/open-sse imports for better
  module resolution
- Replace all as any casts with proper types: ComboModelStep for
  combo step iteration, Record<string, unknown> bracket access for
  custom model fields, ManagedAvailableModel.contextLength type
  for fallback models, and Error instanceof check for catch blocks
- Normalize provider alias resolution in combo context_length
  calculation via resolveCanonicalProviderId for consistent
  getTokenLimit lookups

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/app/api/v1/models/catalog.ts

@@ -8,14 +8,14 @@ import {
   getProviderNodes,
   getModelIsHidden,
 } from "@/lib/localDb";
-import { getAllEmbeddingModels } from "@omniroute/open-sse/config/embeddingRegistry.ts";
-import { getAllImageModels } from "@omniroute/open-sse/config/imageRegistry.ts";
-import { getAllRerankModels } from "@omniroute/open-sse/config/rerankRegistry.ts";
-import { getAllAudioModels } from "@omniroute/open-sse/config/audioRegistry.ts";
-import { getAllModerationModels } from "@omniroute/open-sse/config/moderationRegistry.ts";
-import { getAllVideoModels } from "@omniroute/open-sse/config/videoRegistry.ts";
-import { getAllMusicModels } from "@omniroute/open-sse/config/musicRegistry.ts";
-import { REGISTRY } from "@omniroute/open-sse/config/providerRegistry.ts";
+import { getAllEmbeddingModels } from "@omniroute/open-sse/config/embeddingRegistry";
+import { getAllImageModels } from "@omniroute/open-sse/config/imageRegistry";
+import { getAllRerankModels } from "@omniroute/open-sse/config/rerankRegistry";
+import { getAllAudioModels } from "@omniroute/open-sse/config/audioRegistry";
+import { getAllModerationModels } from "@omniroute/open-sse/config/moderationRegistry";
+import { getAllVideoModels } from "@omniroute/open-sse/config/videoRegistry";
+import { getAllMusicModels } from "@omniroute/open-sse/config/musicRegistry";
+import { REGISTRY } from "@omniroute/open-sse/config/providerRegistry";
 import { getAllSyncedAvailableModels } from "@/lib/db/models";
 import { getCompatibleFallbackModels } from "@/lib/providers/managedAvailableModels";
 import { hasEligibleConnectionForModel } from "@/domain/connectionModelRules";
@@ -25,8 +25,9 @@ import {
   getCatalogDiagnosticsHeaders,
 } from "@/lib/modelMetadataRegistry";
 import { isAuthRequired, isDashboardSessionAuthenticated } from "@/shared/utils/apiAuth";
-import { parseModel } from "@omniroute/open-sse/services/model.ts";
-import { getTokenLimit } from "@omniroute/open-sse/services/contextManager.ts";
+import { parseModel } from "@omniroute/open-sse/services/model";
+import { getTokenLimit } from "@omniroute/open-sse/services/contextManager";
+import type { ComboModelStep } from "@/lib/combos/steps";
 
 const FALLBACK_ALIAS_TO_PROVIDER = {
   ag: "antigravity",
@@ -321,10 +322,11 @@ export async function getUnifiedModelsResponse(
       // they fall back to a conservative ~4000 token limit, causing truncation.
       const comboContextLength = Array.isArray(combo.models)
         ? combo.models
-            .filter((step) => step && step.kind === "model" && step.model)
+            .filter((step): step is ComboModelStep => step?.kind === "model" && Boolean(step.model))
             .map((step) => {
               const parsed = parseModel(step.model);
-              const provider = parsed.provider || (step as any).providerId || "unknown";
+              const rawProvider = parsed.provider || step.providerId || "unknown";
+              const provider = resolveCanonicalProviderId(rawProvider);
               const model = parsed.model || step.model;
               return getTokenLimit(provider, model);
             })
@@ -732,8 +734,8 @@ export async function getUnifiedModelsResponse(
             ...(endpoints.length > 1 || !endpoints.includes("chat")
               ? { supported_endpoints: endpoints }
               : {}),
-            ...(typeof (model as any).inputTokenLimit === "number"
-              ? { context_length: (model as any).inputTokenLimit }
+            ...(typeof model["inputTokenLimit"] === "number"
+              ? { context_length: model["inputTokenLimit"] as number }
               : {}),
             ...(visionFields || {}),
           });
@@ -757,8 +759,8 @@ export async function getUnifiedModelsResponse(
               parent: aliasId,
               custom: true,
               ...(modelType ? { type: modelType } : {}),
-              ...(typeof (model as any).inputTokenLimit === "number"
-                ? { context_length: (model as any).inputTokenLimit }
+              ...(typeof model["inputTokenLimit"] === "number"
+                ? { context_length: model["inputTokenLimit"] as number }
                 : {}),
               ...(providerVisionFields || {}),
             });
@@ -793,9 +795,7 @@ export async function getUnifiedModelsResponse(
         const visionFields =
           getVisionCapabilityFields(aliasId) || getVisionCapabilityFields(modelId);
         const contextLength =
-          typeof (model as any).contextLength === "number"
-            ? (model as any).contextLength
-            : undefined;
+          typeof model.contextLength === "number" ? model.contextLength : undefined;
 
         models.push({
           id: aliasId,
@@ -873,7 +873,7 @@ export async function getUnifiedModelsResponse(
     return Response.json(
       {
         error: {
-          message: (error as any).message,
+          message: error instanceof Error ? error.message : String(error),
           type: "server_error",
           code: INTERNAL_PROXY_ERROR,
         },

src/lib/providers/managedAvailableModels.ts

@@ -4,6 +4,7 @@ import { isClaudeCodeCompatibleProvider } from "@/shared/constants/providers";
 type ManagedAvailableModel = {
   id?: string;
   name?: string;
+  contextLength?: number;
 };
 
 export function getCompatibleFallbackModels(