feat(broadcasts): add duplicate endpoint

[gabrielmfern]

This ports resend.broadcasts.duplicate(id) from the Node SDK as BroadcastDuplicateAsync, for the POST /broadcasts/{id}/duplicate endpoint added in resend/resend-openapi#115, plus a broadcast duplicate command in the deprecated CLI. It is a hand port, since the tools/dotnet-gen generator refuses Broadcasts. The release carries 0.18.0.

Claude called the new method against staging from a scratch console app and ran the CLI command once, then deleted both copies with httpie. The test keeps Assert.NotEqual( broadcastId, resp.Content ) on purpose: it is the assertion that separates a duplicate from an update against the fake server.

Success:   True
Source id: e6bd3843-3cc7-4c0d-b7fd-e01cbb514a16
New id:    b696b590-6c4c-43b1-b45d-9cbcf9eb6912
Differs:   True

GET /broadcasts/b696b590-6c4c-43b1-b45d-9cbcf9eb6912 -> HTTP/1.1 200 OK
{"object":"broadcast","id":"b696b590-6c4c-43b1-b45d-9cbcf9eb6912","name":"Untitled (copy)","status":"draft",...}

DELETE /broadcasts/b696b590-6c4c-43b1-b45d-9cbcf9eb6912 -> HTTP/1.1 200 OK
{"object":"broadcast","id":"b696b590-6c4c-43b1-b45d-9cbcf9eb6912","deleted":true}

$ resend broadcast duplicate e6bd3843-3cc7-4c0d-b7fd-e01cbb514a16
01b8fc5c-3023-40bf-b641-324325ee1a77

DELETE /broadcasts/01b8fc5c-3023-40bf-b641-324325ee1a77 -> HTTP/1.1 200 OK
{"object":"broadcast","id":"01b8fc5c-3023-40bf-b641-324325ee1a77","deleted":true}

🤖 Generated with Claude Code

---

Summary by cubic

Adds the ability to duplicate a broadcast through the .NET SDK and the deprecated CLI, porting the Node SDK's resend.broadcasts.duplicate(id).

Changes

• Adds BroadcastDuplicateAsync to IResend and ResendClient, calling POST /broadcasts/{id}/duplicate.
• Adds the broadcast duplicate CLI command.
• Adds a fake-server route and a test asserting the duplicate ID differs from the source.
• Bumps the package version to 0.18.0.

^{Written for commit c8c6332. Summary will update on new commits.}

[cubic-dev-ai]

1 issue found across 8 files

Confidence score: 4/5

• src/Resend/IResend.cs adds a duplicate-operation API call whose production authorization requirements are not yet confirmed; broadcast API keys may be rejected at runtime if they lack permission for the endpoint—verify the required key permissions and restrictions before merging.

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="src/Resend/IResend.cs">

<violation number="1" location="src/Resend/IResend.cs:864">
P2: Custom agent: **API Key Permission Check SDK Methods**

This adds a new Resend API operation. Confirm that the production API keys used for broadcasts have permission to call the duplicate endpoint, including any restricted keys, before release.</violation>
</file>

<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>