Google Antigravity 1.2.3 release notes

Added the /copy btw slash subcommand to copy the full text of the active /btw side-question response to the clipboard even when the response card is collapsed or scrolled, along with argument ghost hints when typing /copy.
Improved tool-calling fidelity by translating per-request tool-choice constraints (any, required, and named functions) into native backend function-calling configurations.
Fixed the /hooks command and hook inspection utilities omitting hooks bundled inside enabled plugins when listing active hooks.json configurations.
Fixed custom subagents created with enable_mcp_tools: true receiving an empty MCP server list instead of inheriting the parent agent's configured MCP servers, and fixed declarative subagent configurations failing to resolve relative config file paths (relative_path_to_config) against the parent agent's directory.
Fixed proactive feedback prompts triggering prematurely during the first few turns of a session or on transient, recovered tool errors.

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