feat: super properties for posthog-node

[harshit078]

Problem

• This PR address issue Super properties for posthog-node #2727
• added super properties in posthog-node

Changes

• added registeredProperties in prepareEventMessage
• this allows prepareEventMessage to ensure that every event includes globally registered super properties.
• Added tests to verify the correct behavior of property registration and overriding.

Release info Sub-libraries affected

Libraries affected

• All of them
• posthog-js (web)
• posthog-js-lite (web lite)
• posthog-node
• posthog-react-native
• @posthog/react
• @posthog/ai
• @posthog/nextjs-config
• @posthog/nuxt
• @posthog/rollup-plugin
• @posthog/webpack-plugin

Checklist

• Tests for new code
• Accounted for the impact of any changes across different platforms
• Accounted for backwards compatibility of any changes (no breaking changes!)
• Took care not to unnecessarily increase the bundle size

If releasing new changes

• Ran pnpm changeset to generate a changeset file
• Added the "release" label to the PR to indicate we're publishing new versions for the affected packages

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[harshit078]

Hey @pauldambra , can you review the PR ? Thanks !

[lucasheriques]

hey Harshit! I'll review this one tomorrow - got stuck today fixing some other issues, but it's on my list

[lucasheriques]

Thanks for the PR! The implementation looks good and the tests are solid.

One thing to clarify: since the Node SDK uses in-memory storage, register() properties only persist for the lifetime of the PostHog client instance. This is useful for long-running processes (Express servers, workers) but won't help in serverless environments where each invocation creates a new client.

Before merging, could you:

1. Run pnpm changeset to generate a changeset (I see it's unchecked in the PR checklist)
2. Add JSDoc to the register() method in the Node SDK explaining the behavior:
3. Optionally, a docs update in the posthog.com repo (contents/docs/libraries/node/index.mdx) would be great but can be a follow-up

[harshit078]

Hey @lucasheriques , sure I'll do the 3 steps and update the PR. Thanks !

[github-actions]

This PR hasn't seen activity in a week! Should it be merged, closed, or further worked on? If you want to keep it open, post a comment or remove the stale label – otherwise this will be closed in another week.

[github-actions]

This PR hasn't seen activity in a week! Should it be merged, closed, or further worked on? If you want to keep it open, post a comment or remove the stale label – otherwise this will be closed in another week.

[github-actions]

This PR hasn't seen activity in a week! Should it be merged, closed, or further worked on? If you want to keep it open, post a comment or remove the stale label – otherwise this will be closed in another week.

[harshit078]

Hey @lucasheriques, I've updated the changeset as required. If needed this PR can be reviewed again. Thanks !

[github-actions]

This PR hasn't seen activity in a week! Should it be merged, closed, or further worked on? If you want to keep it open, post a comment or remove the stale label – otherwise this will be closed in another week.

[github-actions]

This PR was closed due to lack of activity. Feel free to reopen if it's still relevant.