Fix OpenAI Codex model discovery for RLM subagents

[nickadminroot]

Summary

• use a dedicated Codex-compatible client version for OpenAI Codex model discovery
• restore GPT-5.6 Luna, Sol, and Terra to the executable RLM model catalog
• add a regression test for the discovery URL and Luna visibility

Fixes #639.

Validation

• npx tsx ../../node_modules/vitest/dist/cli.js --run test/suite/regressions/639-codex-discovery-client-version.test.ts
• npm run check
• live Codex catalog request with client_version=0.144.0 returned Luna, Sol, and Terra

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Note

Low Risk
Narrow change to the Codex discovery query parameter plus a regression test; no auth, inference, or data-path changes.

Overview
Fixes RLM/subagent model discovery for OpenAI Codex when GPT-5.6 models (e.g. Luna, Sol, Terra) were missing from the executable catalog.

OpenAI Codex’s /models endpoint filters the catalog by client_version, and it expects a Codex CLI semver, not Prime Agent’s app version. The discovery URL now sends client_version=0.144.0 (documented as the first catalog version that advertises GPT-5.6) instead of the agent VERSION.

A regression test asserts the discovery fetch uses 0.144.0 and that findRlmModels can surface a matching Codex model.

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Note

Fix OpenAI Codex model discovery by pinning client_version to 0.144.0

The Codex catalog gates GPT-5.6 model availability by the Codex CLI semver passed as client_version in the discovery URL. Previously, the agent's own version was used, which caused GPT-5.6 models to be omitted from RLM model discovery. The fix pins client_version to 0.144.0 (the first catalog version advertising GPT-5.6) in model-registry.ts. A regression test in 639-codex-discovery-client-version.test.ts verifies the correct version is sent.

^{Macroscope summarized 091c2f9.}

[sethkarten]

Thank you for the report and proposed work. This root cause is now covered by maintainer-owned stacked PR #1164, authored independently from upstream/main.

We did not inspect or reuse this PR's diff, branch, commits, implementation code, or tests; its public description/comments were used only as a bug report. To keep one review surface, this PR is superseded by #1164 and is being closed.

The complete review stack is #1158–#1165. It is being left unmerged for human review after CI and review-bot findings are cleared.