DevAgentRadar → Google Antigravity

Goal: turn this release signal into a safe pilot plan for my stack.

Context

Assistant: Google Antigravity Proposal: Set excludeDefaultComponents: true on custom Antigravity agents Summary: Antigravity 1.2.1 adds excludeDefaultComponents: true in custom agent Markdown frontmatter so agents drop default prompt sections and built-in tools while keeping post-invocation hooks. MCP open object schemas are preserved, --continue resumes the right conversation from subdirectories, and --sandbox status is accurate. Primary source: https://github.com/google-antigravity/antigravity-cli/releases/tag/1.2.1

Why it matters

Custom agents previously always inherited default prompt sections and built-in tools. 1.2.1 lets you set excludeDefaultComponents: true in Markdown frontmatter to strip those while still running post-invocation hooks, which is the right setup for specialized agents that should not pull in generic tools. MCP and provider tools that used open object schemas ({"type": "object"} or additionalProperties: true) were incorrectly rejecting undeclared arguments; those schemas now work, so extra fields no longer need to be enumerated. --continue no longer starts a brand-new conversation when launched from a subdirectory, after a crash, or with another session open—it falls back to the most recent non-empty conversation in the current workspace or parent/child directories. Transient genai.APIError 502/503/504, per-minute 429, and mid-stream interruptions retry in-process with exponential backoff while keeping completed tool call outputs, so do not abandon a turn on the first blip. Launch with --sandbox and trust the status line; it no longer reports the sandbox as disabled when that flag was used.

Suggested actions

1. Add excludeDefaultComponents: true to the YAML frontmatter of every custom agent Markdown file so those agents opt out of default prompt sections and built-in tools while still running post-invocation hooks.
2. For MCP and provider tools that should accept extra fields, set the input schema to {"type": "object"} or additionalProperties: true; Antigravity 1.2.1 now preserves those open object schemas instead of rejecting undeclared arguments.
3. From a workspace subdirectory, after a crash, or while another session is open, resume with the Antigravity CLI --continue flag so it falls back to the most recent non-empty conversation in the current workspace or its parent/child directories.
4. Relaunch the interactive session with --sandbox and confirm the status line reports the terminal sandbox as enabled; 1.2.1 fixed it showing disabled when that flag was used.
5. If a turn hits a transient genai.APIError 502, 503, 504, per-minute 429, or a mid-stream interruption, stay in the same session—1.2.1 retries in-process with exponential backoff and preserves completed tool call outputs; treat only unrecovered 503 and 429 messages as the real stop.

Config surfaces this release may change

• hooks (high confidence) — check your repo before applying
• subagent definitions (high confidence) — check your repo before applying
• MCP servers — check your repo before applying
• background and headless runs — check your repo before applying
• sandbox settings — check your repo before applying

After you finish

Do not report this as applied to DevAgentRadar. You cannot write the visitor's loop.

Tell the human: open https://devagentradar.com/proposals/google-antigravity-1-2-1-set-excludedefaultcomponents-true-on-custom-ant and mark Applied, Skipped, or Failed. Proposal id: 31b2677c-1158-48d7-bc18-5a4f8a365b3a

Please:

1. Map the change to concrete pilot steps
2. Flag security / permission implications
3. Keep the pilot reversible