fix(types): preserve vision capability literal (#9121)

Validated in local merge-train (devbox-vm-06-dev002) @ combined-tip (FAST gates: typecheck/complexity/cognitive/changelog/vitest — only pre-existing audit.test.ts flake). Evidence: /home/diegosouzapw/dev/proxys/OmniRoute/.claude/worktrees/merge-train-20260805-222248-suite.log

changelog.d/maintenance/8484-vision-capability-literal.md

@@ -0,0 +1 @@
+- **fix(types):** preserve the literal `capabilities.vision: true` contract for catalog vision fields so custom-model capability composition remains type-safe under TypeScript 7 ([#9121](https://github.com/diegosouzapw/OmniRoute/pull/9121))

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

@@ -6,7 +6,11 @@ import { isVisionModelId } from "@/shared/constants/visionModels";
 // Re-exported (here and from ./catalog.ts) for callers/tests that imported it from there.
 export { isVisionModelId };
 
-export function getVisionCapabilityFields(modelId: string) {
+export function getVisionCapabilityFields(modelId: string): {
+  capabilities: { vision: true };
+  input_modalities: string[];
+  output_modalities: string[];
+} | null {
   if (!isVisionModelId(modelId)) return null;
   return {
     capabilities: { vision: true },

tests/unit/catalog-helpers-extraction.test.ts

@@ -141,6 +141,12 @@ test("catalogVision: re-exports isVisionModelId and derives capability fields",
   // id-based heuristic
   const visionFields = getVisionCapabilityFields("gpt-4o");
   assert.ok(visionFields, "gpt-4o must be detected as vision-capable");
+  const typedVisionFields: {
+    capabilities: { vision: true };
+    input_modalities: string[];
+    output_modalities: string[];
+  } | null = visionFields;
+  assert.equal(typedVisionFields?.capabilities.vision, true);
   assert.equal(visionFields?.capabilities.vision, true);
   assert.equal(getVisionCapabilityFields("kimi-k2"), null);
 });