/model switches, primary-model fallback, and credential-pool key
rotation all change the prompt-cache key (model and/or account), so
the next turn re-reads the entire conversation at full input price.
Add cost warnings everywhere docs recommend or describe these paths:
- reference/slash-commands.md: cost note on both /model rows
- user-guide/features/fallback-providers.md: warning admonition
- user-guide/features/credential-pools.md: warning admonition
- user-guide/configuring-models.md: mid-session switch warning
- guides/tips.md: expand cache tip + /model tip
- reference/faq.md: warning on the switch-back-and-forth example
- user-guide/desktop.md: composer picker bullet
- developer-guide/context-compression-and-caching.md: new
cache-aware design pattern (model identity is part of the key)