GitHub Copilot: static default model list shadows live entitlement discovery

Summary

The GitHub Copilot provider ships a live model-discovery hook (fetchCopilotModelCatalog) that fetches ${baseUrl}/models and is explicitly documented as tracking "per-account entitlements + accurate context windows without manifest churn." In practice, however, the static default catalog (extensions/github-copilot/models-defaults.ts DEFAULT_MODEL_IDS + openclaw.plugin.json manifest models) is what seeds the user-facing model picker and openclaw models list.

When Copilot adds a new model (e.g. claude-opus-4.8), entitled accounts can call it successfully, but it does not appear in the picker / models list until the static list is bumped or the user hand-edits config. This defeats the stated purpose of the discovery hook.

Reproduction

1. Account entitled to a model newer than the static list (e.g. claude-opus-4.8).
2. GET https://api.githubcopilot.com/models returns it (verified: 41 models incl. claude-opus-4.8).
3. openclaw models list --provider github-copilot does not show it.
4. A direct --model github-copilot/claude-opus-4.8 agent call succeeds (no fallback) — proving entitlement and routing both work; only discovery/visibility is missing.

Impact

• Newly entitled Copilot models are invisible/unselectable until a release bumps the static list.
• Users must manually add models.providers.github-copilot.models[] entries + aliases to use a model their plan already includes.
• A confusing ⚠️ Gateway: agents.defaults.models.github-copilot/<model> failed warning can appear for config keys containing the provider/model slash, even when the model resolves and runs fine.

Proposed fix

1. Picker/catalog should present the union of live-discovered models and static defaults, deduped by id, with live metadata winning (context window, vision, reasoning). The static list becomes a fallback for offline/discovery-failure only.
2. Keep the 30s live-catalog cache; on discovery success, merge rather than letting static defaults gate visibility.
3. (Minor) Improve the gateway warning so a model id containing / in a config key path doesn't render as a spurious "failed" path.

Interim

PR #88547 adds claude-opus-4.8 to the static catalog as an immediate unblock.

Environment

• OpenClaw 2026.5.28
• Provider: github-copilot
• Verified live /models returns claude-opus-4.8 for the affected account.