No-op try/except in handle_submit catches AgentVersionNotAvailableError only to re-raise it

[nficano]

Category: clean-code Severity: minor
Location: src/arcp/_runtime/_handlers.py:102-105

What

Catching an exception solely to raise it again is a no-op: AgentNotAvailableError (also raised by _resolve_agent) propagates identically with or without the handler, and AgentVersionNotAvailableError is re-raised unchanged. The try/except adds no behavior and obscures intent.

Evidence

    try:
        agent_fn, name, version = runtime._resolve_agent(submit.agent)
    except AgentVersionNotAvailableError:
        raise

Proposed fix

Remove the try/except and call runtime._resolve_agent(submit.agent) directly; both error types already propagate to _dispatch_one which maps them to session.error.

Acceptance criteria

• The redundant try/except is removed and agent-resolution errors still surface as session.error; tests for unknown agent / unknown version still pass.