Seems like most popular harnesses, including codex and Claude code, support Agent Skills (an open spec for skill formatting/ organization): https://agentskills.io/clients

Which is to say, this isn't really a lock-in/ stickiness vector (unless maybe the wording itself of a skill is hyper-optimized for a specific model)

you can simply switch to z.ai/GLM-5.2 inside Claude Code by settings env variables in .claude/settings.json