Codex namespace flattening can exceed upstream function-name limits

[haoshan98]

Description

While validating Codex support, we found that flattened namespace member names can exceed the 64-character limit used by some Responses-compatible providers.

amespace members are currently flattened as:

agentic_ns__{namespace}__{member}

For example, the following generated name is 76 characters:

agentic_ns__mcp__codex_apps__github___remove_reaction_from_pr_review_comment

Steps to reproduce

1. Send a Codex request containing the mcp__codex_apps__github namespace and
   _remove_reaction_from_pr_review_comment member.
2. The gateway forwards the 76-character flattened name as an upstream function declaration.
3. An upstream provider enforcing a 64-character limit rejects the request before inference, typically with HTTP 422.

Expected behavior

Gateway-generated namespace member names should stay within the upstream limit and still be restored to the original public { namespace, name } representation in the response.

Actual behavior

The gateway forwards the full flattened name without a length bound, allowing one long namespace member to reject the entire request.

Environment

No response

Additional context

A likely direction is to preserve short names and shorten only long generated names using a readable prefix plus a
deterministic fingerprint. The existing request-scoped namespace map can restore the original names without parsing the shortened value.

[maralbahari]

addressed in #135