Antigravity generateContent failed (HTTP 400 Bad Request)

When ill write "Hello" or a simpel line ill recieve the following message:

Antigravity generateContent failed (HTTP 400 Bad Request): {
  "error": {
    "code": 400,
    "message": "Function call is missing a thought_signature in functionCall parts. This is required for tools to work correctly, and missing thought_signature may lead to degraded model performance. Additional data, function call `default_api:ls` , position 3. Please refer to https://ai.google.dev/gemini-api/docs/thought-signatures for more details.",
    "status": "INVALID_ARGUMENT"
  }
}

another issue when copy a large tekst into the prompt.

  ✓ websearch 'palo alto wildfire xpath size limit' · 938 tok

Antigravity generateContent failed (HTTP 400 Bad Request): {
  "error": {
    "code": 400,
    "message": "Function call is missing a thought_signature in functionCall parts. This is required for tools to work correctly, and missing thought_signature may lead to degraded model performance. Additional data, function call `default_api:websearch` , position 6. Please refer to https://ai.google.dev/gemini-api/docs/thought-signatures for more details.",
    "status": "INVALID_ARGUMENT"
  }
}

↪ Fallback available: press Ctrl+Y to switch to claude-opus-4-6-thinking via https (Antigravity) and resend.

Reproduce the failure with a simple “Hello” prompt and with a large pasted prompt, then trace the generateContent request path and tool-call handling. Use the reported default_api:ls and default_api:websearch errors as starting points; done means these requests no longer fail because the required thought_signature is missing.