v1.21.0

1.21.0 (2026-07-24)

Full Changelog: v1.20.0...v1.21.0

Features

• api: add claude-opus-5 model (3e67b3d)
• api: add tool addition/removal blocks and tool_change events (3e67b3d)
• api: expand client-side fallback credit token types and add server-side fallbacks default option (3e67b3d)

Bug Fixes

• client: honor ANTHROPIC_BASE_URL in API requests (#43) (0dcaa4f)

Chores

• bump dependency (8358acd)
• ci: cap macOS notarize timeout at 40m; add notary-status debug workflow (#42) (3aa7a80)