Hi Vercel team,

I’m looking for an authoritative technical clarification regarding the first-commit behavior of git.deploymentEnabled in vercel.json.

Our setup:

• GitHub-connected Next.js project
• Production branch: main
• Preview branch: staging
• Automatic Git deployments currently enabled
• Preview environment contains sensitive application credentials

We plan to introduce the following configuration for the first time:

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{
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  "git": {
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    "deploymentEnabled": {
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      "staging": false
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    }
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  }
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}

Questions for Vercel Engineering:

1. When a push webhook arrives, does Vercel read vercel.json from the incoming commit SHA before deciding whether to create a deployment?
2. Does this setting suppress the Preview deployment of the same first commit introducing the rule, rather than only subsequent commits?
3. Is suppression enforced before dependency installation, build execution, prerendering, and access to Preview environment variables?
4. Does this rule leave automatic Production deployments from main unchanged?
5. If first-commit suppression cannot be guaranteed, is there an officially supported branch-specific pre-push control that does not affect main?

The Vercel Git Configuration documentation explains branch-level deployment disabling, but does not explicitly document the first-commit evaluation order.

Vercel Agent initially confirmed the intended behavior, but subsequently acknowledged that the exact ordering is not documented as a public engineering guarantee.

Because Preview contains sensitive credentials, we cannot safely use a test push to discover the behavior.

Could a Vercel engineer or staff member confirm this with an authoritative reference or explain the relevant implementation guarantee?

Thank you!