release: v0.7.0 — remove CodexRuntime adapter

[pofallon]

Summary

• Removes CodexRuntime, CodexOptions, the [codex] pip extra (openai-codex-sdk>=0.1.11), examples/probe_codex.py, docs/adapters/codex.md, and the four Codex test modules — plus every cross-reference in src docstrings, per-adapter docs, README, and CLAUDE.md.
• Breaking change for direct users of CodexRuntime or airframe-agents[codex]. Per pre-1.0 SemVer convention the minor is bumped: 0.6.3 → 0.7.0. CHANGELOG entry under ## [0.7.0] — 2026-05-19.
• Reserves the \"codex\" provider ID for a possible future adapter wrapping the official openai-codex Python SDK once it leaves alpha. The ID is not re-usable for any other vendor.
• This PR also bundles the previously-merged KimiRuntime additions (PR feat(kimi): KimiRuntime scaffolding (Iteration A) #11) into the same release section, so v0.7.0 is the combined Kimi-add + Codex-remove cut.

Why remove CodexRuntime?

Two things converged into the same root cause:

1. Murky provenance of what we were wrapping. openai-codex-sdk on PyPI self-declares author: OpenAI but it does not live in OpenAI's official github.com/openai/codex repo, and it has fallen behind the Codex CLI's recent releases.
2. The actually-official Python SDK is a different package and a different architecture. OpenAI ships openai-codex (currently v0.131.0a4 — still alpha) at github.com/openai/codex/sdk/python, structured as a JSON-RPC app-server v2 over stdio. Not a drop-in replacement. And — critically — neither Python package exposes client.models.list() (only the Node @openai/codex SDK does).

That made the post-v0.6.3 doctor false-negative Maverick hit — list_models() rejecting ChatGPT OAuth tokens against api.openai.com/v1/models — fundamentally unfixable from inside CodexRuntime.list_models() without hand-rolling more code on top of a package whose maintainership we can't verify. Wrapping uncertain-provenance code isn't earning its weight pre-1.0; cleaner to remove and revisit once the official openai-codex package stabilises.

Migration

Direct users of CodexRuntime should either:

• pin airframe-agents<0.7, or
• migrate to a still-supported adapter: ClaudeCodeRuntime, CopilotRuntime, BedrockRuntime, or an OpenAI-compat gateway (OpenCodeZenRuntime / OpenCodeGoRuntime / OpenRouterRuntime). Codex subscription holders can route through opencode adapters, which already accept the Codex provider on the opencode side.

Test plan

• make ci green locally — 855 passed, 34 skipped after the scrub.
• uv lock refreshed; openai-codex-sdk v0.1.11 no longer pinned.
• No remaining CodexRuntime / CodexOptions / codex.py references in src, tests, docs, README, or CLAUDE.md (verified with grep).
• CI green on the PR.
• Manually verify post-merge release-on-tag workflow publishes 0.7.0 to PyPI.

🤖 Generated with Claude Code