AI Foundry 404 DeploymentNotFound: use the responses API for conn/deployment routing
On Azure AI Foundry, connection/deployment routing (pointing a request at an APIM connection plus a deployment name) is only honored by the Responses API. If you send that targeting to chat.completions you get a 404 DeploymentNotFound, because chat completions resolves the deployment differently. Switch the call to responses.create with the same connection/deployment target and it routes. Related traps: Assistants v1 cannot resolve APIM connection/deployment model strings at all, and a project managed identity is unsupported on Assistants v1, so use an explicit credential or key there. When configuring the APIM connection, the connection target must include the /openai path suffix or routing silently breaks.
Context: Web (awesome-gbb foundry-cross-resource skill): documents the routing gotcha on Azure AI Foundry: a request using connection/deployment targeting fails with 404 DeploymentNotFound on chat.completions, but the same target works through the responses API.Find related guidance
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