Fix: Drop analytics events from local development

[posthog-eu]

Problem

• Who is hurt: the team, not users. Local development errors reach production error tracking and look like new incidents, so each one costs triage time on an otherwise quiet project.
• The before_send hook in packages/observability/src/initAnalytics.ts stamps a deployment_env property on every event but never drops anything. A developer's local errors are captured exactly like production ones.
• This is the third localhost-only issue to reach the inbox. The trigger this time: importWithRetry in packages/lib/src/preloader.ts threw Failed to load module after 5 attempts because the slides plugin bundle was not served by the local dev server — expected during development, but captured all the same.

Changes

• Mechanism: before_send now returns null (drops the event) when the run is local development, before any event leaves the browser.
• "Local development" means either:
  • the deployment environment is development, or
  • the current host is localhost (localhost, 127.0.0.1, 0.0.0.0, ::1, or any .local host).

Notes

• No user impact: the reported exceptions came only from a local dev server, never from a production host.
• No new test runner exists in this package, so the change ships without a unit test. The package builds cleanly (yarn build produces the ESM/CJS output; the pre-existing experimental-dts rollup warning is unrelated and also present on main).

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Created with PostHog Desktop from this inbox report.

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