feat: allow overriding Resend API key and specifying from address via CLI flag

[josepjaume]

Description

This PR adds support for passing a Resend API key directly via a CLI flag (--resend-api-key) to the dev command, allowing users to override the stored configuration without modifying their config file.

Changes

• Added --resend-api-key <key> option to the dev command CLI
• Added --from <address> option to the dev command CLI
• Updated the dev command handler to accept and pass through the resendApiKey parameter
• Modified startDevServer to accept an optional resendApiKey parameter
• Updated the preview server initialization to use the CLI-provided API key if available, falling back to the stored config value

Motivation

This enables users to:

• Temporarily use a different Resend API key without modifying their stored configuration
• Use different API keys in different environments or CI/CD pipelines
• Override the default config on a per-command basis

Test Plan

The change is straightforward and follows the existing pattern for CLI options. Verify that:

• Running dev --resend-api-key <key> correctly passes the key to the preview server
• The CLI flag takes precedence over the stored config value
• Omitting the flag falls back to the stored config as before

https://claude.ai/code/session_01S5bPtnwuCfk37VUe6RFHT7

---

Summary by cubic

Add --resend-api-key and --from to the dev command to run the preview server with a custom Resend API key and sender. When both are set, test emails send directly via your Resend account instead of the hosted API; includes minor formatting fixes in preview-server components.

• New Features
  • dev now accepts --resend-api-key and --from
  • Preview app uses local Resend send when both are provided; otherwise falls back to stored config and the hosted test endpoint

^{Written for commit 2b91d05. Summary will update on new commits.}

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Latest commit: 2b91d05

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[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/resend/react-email/@react-email/preview-server@2978

npm i https://pkg.pr.new/resend/react-email@2978

commit: 2b91d05

[cubic-dev-ai]

No issues found across 3 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

[cubic-dev-ai]

1 issue found across 9 files (changes from recent commits).

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="packages/preview-server/src/actions/send-email.ts">

<violation number="1" location="packages/preview-server/src/actions/send-email.ts:30">
P1: Custom agent: **API Key Permission Check SDK Methods**

This PR introduces a new Resend SDK method (`emails.send`) but does not include an explicit permission-readiness check/reminder for production API keys. Per the API Key Permission Check SDK Methods rule, confirm and document that deployed Resend keys have send-email permission before rollout to prevent runtime authorization failures.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[cubic-dev-ai]

P1: Custom agent: API Key Permission Check SDK Methods

This PR introduces a new Resend SDK method (emails.send) but does not include an explicit permission-readiness check/reminder for production API keys. Per the API Key Permission Check SDK Methods rule, confirm and document that deployed Resend keys have send-email permission before rollout to prevent runtime authorization failures.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At packages/preview-server/src/actions/send-email.ts, line 30:

<comment>This PR introduces a new Resend SDK method (`emails.send`) but does not include an explicit permission-readiness check/reminder for production API keys. Per the API Key Permission Check SDK Methods rule, confirm and document that deployed Resend keys have send-email permission before rollout to prevent runtime authorization failures.</comment>

<file context>
@@ -0,0 +1,43 @@
+
+    const resend = new Resend(resendApiKey);
+
+    const response = await resend.emails.send({
+      from: fromAddress,
+      to: [parsedInput.to],
</file context>