Subscription routing

Subscription routing — contract and behavior

• model: codex-subscription targets that named subscription-backed provider.
• model: any randomizes the active supported subscriptions visible to the signed agent and falls through the list on provider failure.
• model: any-vision-capable filters to providers whose current path can materialize image_url content; the documented implementation uses Claude Code-backed subscriptions.
• model: task:<task-name> ranks measured observations from the journal, randomizes score ties, and retries candidates in rank order.
• The router never guesses a task name from prompt content and has no hard-coded provider priority for task routing.