Support invoking a specific runtime endpoint with `agentcore invoke --endpoint <name>`

[jariy17]

Summary

agentcore invoke always calls a runtime's DEFAULT endpoint. There is no way to invoke a specific named runtime endpoint (version alias) created with agentcore add runtime-endpoint. Please add a flag (e.g. --endpoint <name>) to agentcore invoke to target a specific endpoint.

Current behavior

• agentcore add runtime-endpoint --runtime MyAgent --endpoint control --version 1 creates named endpoints, but agentcore invoke provides no way to call them.
• agentcore invoke exposes --runtime, --target, --gateway, and --gateway-target-name, but no --endpoint.
• --target is easy to mistake for endpoint selection — it actually selects the deployment target (account/region). For example, agentcore invoke --runtime MyAgent --target control fails with Target 'control' not found. Available: default.
• The data-plane invoke helper already accepts an endpoint qualifier (it defaults to DEFAULT), so the underlying call supports this — invoke just never passes a non-default value through.

Requested behavior

Add an endpoint selector to agentcore invoke, for example:

agentcore invoke --runtime MyAgent --endpoint control --prompt "..."

Ideally mirroring the precedent already set by agentcore run eval, which supports:

--endpoint <name>   Runtime endpoint name (e.g. PROMPT_V1).
                    Defaults to AGENTCORE_RUNTIME_ENDPOINT env var, then DEFAULT

i.e. --endpoint plus an AGENTCORE_RUNTIME_ENDPOINT environment-variable fallback would make invoke consistent with run eval.

Use case

Validating multiple runtime versions before/during an A/B test. After creating control (v1) and treatment (v2) endpoints, you can't smoke-test each one directly with agentcore invoke — today the only way to exercise a non-default endpoint is to route traffic through a gateway. Direct per-endpoint invocation would make it much easier to sanity-check each variant before sending live traffic.

Workaround today

Send traffic to the test's gateway invocation URL (the gateway splits across endpoints), or invoke the DEFAULT endpoint only.