Google Antigravity Python SDK — v0.1.21 Release Notes

[karmel]

[0.1.21] - 2026-10-05

This release introduces experimental API isolation via the @beta decorator and .beta namespaces, granular skills configuration for subagents, and bulk hook registration during agent initialization. It also expands typing support for tool context annotations, refines UsageMetadata arithmetic operations, and resolves a critical issue where tool calls with empty string IDs were unintentionally deduplicated.

🌟 Key Highlights

• Experimental API Isolation with Beta Namespaces: Introduces the @beta decorator and google.antigravity.beta module, enabling access to preview and experimental features on class and instance namespaces without polluting the stable API surface.

  from google.antigravity import Agent, LocalAgentConfig
  
  # Access experimental methods via the .beta namespace
  config = LocalAgentConfig(...)
  async with Agent(config) as agent:
      await agent.beta.experimental_feature()

• Declarative Subagent Skills Configuration: Adds skills_config support to SubagentConfig, allowing developers to explicitly configure subagent skill inheritance, override skills, or isolate subagents from parent skills.

  from google.antigravity import SubagentConfig, SubagentOverrideSkillsConfig
  config = SubagentConfig(
      skills_config=SubagentOverrideSkillsConfig(skill_paths=["/path/to/custom_skills"])
  )

• Bulk Hook Registration: Enables registering sequences of hooks at once during Agent session initialization and within HookRunner.

  from google.antigravity import LocalAgentConfig
  
  config = LocalAgentConfig(hooks=[auth_hook, logging_hook, metrics_hook])

---

📋 Detailed Changes

Features & Enhancements

• Beta API Decorator & Namespace: Added @beta and BetaNamespace support to expose preview classes, methods, and properties under dedicated .beta accessors and google.antigravity.beta.
• Subagent Skills Management: Added SubagentSkillsConfig, SubagentInheritSkillsConfig, SubagentNoneSkillsConfig, and SubagentOverrideSkillsConfig to SubagentConfig for declarative control over subagent skills.
• Bulk Hook Registration: Updated HookRunner and Agent session initialization to accept collections of hooks in addition to individual registrations.
• Qualified Typing in Tool Annotations: Expanded ToolRunner string annotation inspection to resolve qualified typing wrappers (typing.Optional, typing.Union, and typing.Annotated) when injecting ToolContext.
• UsageMetadata Arithmetic: Harmonized UsageMetadata.__sub__ typing and zero-value identity behavior to align with UsageMetadata.__add__.
• Tool Inspection: Added __repr__ to ToolWithSchema for clearer terminal output and debugging inspection.

Bug Fixes

• Tool Call Deduplication: Fixed an issue in Conversation.receive_chunks() where tool calls with empty string IDs (id='') were treated as duplicate IDs and dropped; they are now treated as absent IDs and yielded correctly.

[babkbabki18-dev]

[0.1.21] - 2026-10-05

This release introduces experimental API isolation via the @beta decorator and .beta namespaces, granular skills configuration for subagents, and bulk hook registration during agent initialization. It also expands typing support for tool context annotations, refines UsageMetadata arithmetic operations, and resolves a critical issue where tool calls with empty string IDs were unintentionally deduplicated.

🌟 Key Highlights

• Experimental API Isolation with Beta Namespaces: Introduces the @beta decorator and google.antigravity.beta module, enabling access to preview and experimental features on class and instance namespaces without polluting the stable API surface.

  from google.antigravity import Agent, LocalAgentConfig
  
  # Access experimental methods via the .beta namespace
  config = LocalAgentConfig(...)
  async with Agent(config) as agent:
      await agent.beta.experimental_feature()

• Declarative Subagent Skills Configuration: Adds skills_config support to SubagentConfig, allowing developers to explicitly configure subagent skill inheritance, override skills, or isolate subagents from parent skills.

  from google.antigravity import SubagentConfig, SubagentOverrideSkillsConfig
  config = SubagentConfig(
      skills_config=SubagentOverrideSkillsConfig(skill_paths=["/path/to/custom_skills"])
  )

• Bulk Hook Registration: Enables registering sequences of hooks at once during Agent session initialization and within HookRunner.

  from google.antigravity import LocalAgentConfig
  
  config = LocalAgentConfig(hooks=[auth_hook, logging_hook, metrics_hook])

---

📋 Detailed Changes

Features & Enhancements

• Beta API Decorator & Namespace: Added @beta and BetaNamespace support to expose preview classes, methods, and properties under dedicated .beta accessors and google.antigravity.beta.
• Subagent Skills Management: Added SubagentSkillsConfig, SubagentInheritSkillsConfig, SubagentNoneSkillsConfig, and SubagentOverrideSkillsConfig to SubagentConfig for declarative control over subagent skills.
• Bulk Hook Registration: Updated HookRunner and Agent session initialization to accept collections of hooks in addition to individual registrations.
• Qualified Typing in Tool Annotations: Expanded ToolRunner string annotation inspection to resolve qualified typing wrappers (typing.Optional, typing.Union, and typing.Annotated) when injecting ToolContext.
• UsageMetadata Arithmetic: Harmonized UsageMetadata.__sub__ typing and zero-value identity behavior to align with UsageMetadata.__add__.
• Tool Inspection: Added __repr__ to ToolWithSchema for clearer terminal output and debugging inspection.

Bug Fixes

• Tool Call Deduplication: Fixed an issue in Conversation.receive_chunks() where tool calls with empty string IDs (id='') were treated as duplicate IDs and dropped; they are now treated as absent IDs and yielded correctly.