Record tool registration metrics for each sampling request

[copyberry]

Record tool registration metrics for each sampling request

What changed

Add the codex.tools.registered histogram to count finalized tool registrations by exposure and tool_mode, including zero counts for empty exposure categories. Record it once per sampling request before transport retries, excluding hosted tools. These counts describe the registered inventory, not model visibility or tool reachability.

Testing

Add an integration test covering a stream retry, direct and deferred namespace tools, a model-only tool, and hosted web search. Verify that registrations are recorded once, hosted tools are excluded, and metric labels contain no tool names or descriptions.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	🔄 Running since 2026-10-07T23:11:29.321935Z	d0bc8a1	PR opened

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