A Gemini model choice is not an agent-runtime choice. If your CometAPI-backed workflow needs Gemini’s managed sandbox, tool-call hooks, or resumable interactions, verify those contracts through the intended access path before building around them. A successful model response is not that verification.
Google’s July 28 announcement makes the distinction concrete: the antigravity-preview-05-2026 managed agent now defaults to Gemini 3.6 Flash, with explicit model selection through agent_config.model. The sandbox coordination belongs to managed agents in the Gemini Interactions API. It is not a promise that any endpoint serving the model also supplies that runtime.
What you would actually be depending on
Google describes several contracts worth separating from model inference:
- Tool interception: environment hooks run scripts before or after sandbox tool calls. In the announcement’s pre-tool example, a
denydecision skips the call and sends the rejection reason into the model’s context. - Budget continuation:
max_total_tokenscaps input, output, and thinking consumption. At the limit, the interaction returnsincompletewith environment state preserved; continuation usesprevious_interaction_idand a fresh budget. - Environment lifecycle: the Environments API lets applications list, inspect, and delete sandbox sessions, including recovering environment IDs after a disconnect.
These are announced managed-runtime behaviors, not independent reliability measurements. The article points elsewhere for full hook failure-handling semantics; it does not settle what your application should do when a mandatory validation hook times out.
Where CometAPI and CrewAI fit
CometAPI’s August 25 CrewAI guide describes a different division of responsibility: CrewAI orchestrates agents and tasks; CometAPI provides model access. Its integration configures each CrewAI LLM with a model ID, API key, and the OpenAI-compatible base URL https://api.cometapi.com/v1.
That is a concrete option for an application that wants per-agent model routing through one access layer. But the same guide warns that interface compatibility does not guarantee identical tool support or other model capabilities. Its example uses Gemini 3.7 Flash, not 3.6 Flash; it does not establish 3.6 Flash availability through CometAPI, much less exposure of Google’s managed-agent hooks.
For a workflow considering Gemini 3.6 Flash, make two separate checks: whether the selected CometAPI route currently serves that model, and whether the route exposes each required managed-runtime operation. Do not interpret this documentation gap as proof that CometAPI cannot expose those operations. Treat it as an unresolved prerequisite.
A small acceptance plan before choosing the architecture
These are proposed tests, not reported results. Run them against the exact endpoint and pinned client/framework versions intended for deployment, using disposable files and mock external actions.
| Required contract | Acceptance test |
|---|---|
| Pre-tool enforcement | Deny a disposable file write. Confirm the write did not happen and the rejection reached the agent. Separately establish the documented behavior for hook failure or timeout. |
| Budget pause/resume | Set a small budget, observe the incomplete interaction, then continue it. Verify the required files and progress survive instead of assuming a new request resumes work. |
| Disconnect recovery | Interrupt the client, recover the environment identity, inspect its state, and verify cleanup through the chosen path. |
| Safe application recovery | Simulate a timeout after a mock external action succeeds. Verify recovery checks the recorded action before attempting it again. |
For the CrewAI/CometAPI path, explicitly assign ownership of checkpoints and side-effect confirmation to the application design. CometAPI’s guide warns that whole-crew fallback can repeat completed work and duplicate external actions. A crew retry is not interchangeable with Google’s documented interaction continuation. Nor should an unsupported parameter or invalid configuration trigger repeated model switching.
Choose native integration when a mandatory Google runtime contract is verified there but remains unverified on your proposed CometAPI path. The CometAPI guide itself says direct integration can be reasonable when only one provider and its native capabilities are needed. Choose the separately orchestrated CrewAI/CometAPI pattern when its model-access contract fits and you have implemented and tested the required lifecycle behavior. If neither path passes the mandatory checks, stop before deployment—not after a model-name substitution.