feat(runtime/codex): pass agent skills through to Codex

[yaozheng-fang]

What

Bridges an agent's skills into the runtime="codex" path. Previously the codex runtime only flattened the session into a prompt and ignored agent skills entirely, so a Codex-backed agent had none of its skills.

This materializes each skill into \$CODEX_HOME/skills/<name>/SKILL.md (+ resources), where Codex's native skill system discovers, injects and progressively loads them. It's purely prompt- and file-level, so:

• backend-independent — no dependence on the Responses/code-mode tool path (unlike MCP/function tools, which Codex wraps in a namespace type that Ark rejects);
• no config flag — Codex auto-scans the user skill scope \$CODEX_HOME/skills/;
• cloud-safe — CODEX_HOME and the remote-skill download cache both live under the system temp dir (/tmp), the only writable path on the AgentKit runtime (overridable via VEADK_SKILLS_CACHE_DIR).

How

New veadk/runtime/codex/skills.py with sync_skills_to_codex_home(agent, codex_home), called from run_async right after the CODEX_HOME is prepared. It rebuilds the skills/ subdir each run (so it always reflects the agent's current skills) and covers two sources:

• ADK-native skills (google.adk.tools.skill_toolset.SkillToolset in agent.tools): each models.Skill is reconstructed back into a SKILL.md (frontmatter + instructions) plus its resource files (references / assets / scripts).
• Legacy VeADK skills (agent.skills_dict): a local skill directory is linked as-is; a remote skill-space / SkillHub skill is downloaded on demand via veadk.skills.materializer.materialize_remote_skill and linked in.

Everything is best-effort — a skill that fails to materialize is logged and skipped, never aborting the turn.

Validation

• Unit: SkillToolset(skills=[load_skill_from_dir(...)]) → correct SKILL.md with frontmatter + body.
• E2E: put a skill whose body carries a secret only in SKILL.md (not the prompt), run a codex agent against 方舟 (deepseek) through the shim → the model discovers the skill and answers with the secret.
• Remote: listed + downloaded a real SkillHub space's skills (SKILL.md + themes/ / scripts/ / references/) into /tmp, linked into \$CODEX_HOME/skills/, and Codex enumerated all of them.

Note

The remote path via the new veadk.skills.VeSkillRegistry wrapper needs a google-adk that exports SkillRegistry (not in the currently pinned version); the underlying materialize_remote_skill used here works today. Legacy-dict and ADK-native SkillToolset sources are unaffected.

🤖 Generated with Claude Code