Function assertRouting

nodejs/test/e2e/multi_provider_registry.e2e.test.ts:137–200

(
        selectionId: string,
        expectedWireModel: string,
        expectedProviderHeader: string
    )

    });

    async function assertRouting(
        selectionId: string,
        expectedWireModel: string,
        expectedProviderHeader: string
    ): Promise<void> {
        // Two OpenAI-compatible providers, both pointed at the replay proxy so
        // their /chat/completions traffic is captured. They are distinguished on
        // the wire by their per-provider X-Provider header. "alpha" carries two
        // models (multiple models per provider); "delta" carries one.
        const providers: NamedProviderConfig[] = [
            {
                name: "alpha",
                type: "openai",
                wireApi: "completions",
                baseUrl: openAiEndpoint.url,
                apiKey: "alpha-secret",
                headers: { "X-Provider": "alpha" },
            },
            {
                name: "delta",
                type: "openai",
                wireApi: "completions",
                baseUrl: openAiEndpoint.url,
                apiKey: "delta-secret",
                headers: { "X-Provider": "delta" },
            },
        ];
        const models: ProviderModelConfig[] = [
            { id: "sonnet", provider: "alpha", wireModel: "byok-gpt-4o" },
            { id: "haiku", provider: "alpha", wireModel: "byok-gpt-4o-mini" },
            { id: "turbo", provider: "delta", wireModel: "byok-gpt-4-turbo" },
        ];

        const session = await client.createSession({
            onPermissionRequest: approveAll,
            model: selectionId,
            providers,
            models,
        });

        try {
            await session.sendAndWait({ prompt: "What is 5+5?" });
            const exchanges = await waitForExchanges();
            expect(exchanges.length).toBe(1);
            const exchange = exchanges[0];

            // The wire model sent to the provider is the selected model's
            // wireModel, not its provider-qualified selection id.
            expect(exchange.request.model).toBe(expectedWireModel);

            // The request carried the owning provider's custom header, proving
            // the turn was dispatched against the correct provider connection.
            expect(getHeader(exchange, "X-Provider")).toBe(expectedProviderHeader);

            // The provider's API key was applied as an Authorization header.
            expect(getHeader(exchange, "Authorization")).toBeTruthy();
        } finally {
            try {