Add Claude Fable 5.2 support on OpenCode 1, OpenCode 2 and Pi
Merged
AN
9h ago+2928+2928+0123456789012345678901234567890123456789-33-33-01234567890123456789
Add Claude Fable 5.2 support on OpenCode 1, OpenCode 2 and Pi. Worker delivery rebased onto main; see the commit messages.
Summary by cubic
Adds Claude Fable 5.2 (claude-fable-5-2) support on OpenCode 1, OpenCode 2, and Pi with its own catalogue entry: $8/M input, $40/M output, $0.20/M cache reads, 1M context window, and 128K max output tokens. Requests are sent the way Claude Code sends them — adaptive thinking, medium default effort, per-message effort markers, and Anthropic's safety fallback; fast mode stays off until Anthropic enables it for subscription accounts.
- Fable 5.2 has its own refusal recovery family so fallback state never cross-contaminates with Fable 5.1 turns in the same session.
- A compatibility snapshot test keeps every existing model's capabilities, betas, and request bodies byte-identical to how they resolved before this change.