v4.0.0-rc.0: ClickHouse migrations and default env vars

What's Changed

⚠️ ⚠️ This is a pre-release of a new major version and introduced breaking functionality from Langfuse v3.

This release contains the default environment variables and ClickHouse migrations that allow for self-hosted Langfuse v4 deployments. We release this as a pre-release to gather feedback on the migration flow and allow early adopters to easily upgrade. For completely fresh deployments, the code paths in this release are well-tested.

We recommend to hold off from Langfuse v3 -> Langfuse v4 migrations in production environments until a stable release is published.

Please follow our upgrade guide to update an existing environment from Langfuse v3 to Langfuse v4.

Features

• feat(preview): enable cloud AI features on PR previews by @LysanderKie in https://github.com/langfuse/langfuse/pull/15264
• feat(api): reject dataset-run-item surface in events_only mode by @Steffen911 in https://github.com/langfuse/langfuse/pull/15313
• feat(otel): expose uploaded media bytes by @hassiebp in https://github.com/langfuse/langfuse/pull/15354
• feat(search-bar): detangle Ask AI system prompt from injected context (LFE-11003) by @nkabardin in https://github.com/langfuse/langfuse/pull/15292
• feat(web): banner to prompt reload on a new deploy (LFE-10978) by @nkabardin in https://github.com/langfuse/langfuse/pull/15279
• feat(v4): promote events tables to CH migration and flip v4 env defaults by @Steffen911 in https://github.com/langfuse/langfuse/pull/14812
• feat: add periodic runner telemetry by @sumerman in https://github.com/langfuse/langfuse/pull/15365
• feat(search-bar): dogfood the Ask AI prompt as a managed Langfuse prompt (LFE-11004) by @nkabardin in https://github.com/langfuse/langfuse/pull/15305
• feat(mobile): hide keyboard-shortcut hints on touch viewports (LFE-11067) by @nkabardin in https://github.com/langfuse/langfuse/pull/15328
• feat(api): agent-friendly deprecation responses for legacy endpoints (LFE-10895) by @niklassemmler in https://github.com/langfuse/langfuse/pull/15168
• feat(evaluation-rules): enhance evaluation rules unstable API to support legacy trace rules by @marliessophie in https://github.com/langfuse/langfuse/pull/15248
• feat(nav): org/project switcher in the mobile nav drawer (LFE-11067) by @nkabardin in https://github.com/langfuse/langfuse/pull/15330
• feat(table): mobile filters in a bottom sheet, not crammed inline (LFE-11067) by @nkabardin in https://github.com/langfuse/langfuse/pull/15319

Fixes

• fix(worker): bound media retention cleanup batches by @sumerman in https://github.com/langfuse/langfuse/pull/15226
• fix(security): mask analytics integration credentials in get endpoints (LFE-14384) by @niklassemmler in https://github.com/langfuse/langfuse/pull/15296
• fix(worker): route analytics score-export trace enrichment by v4 write mode (LFE-11009) by @niklassemmler in https://github.com/langfuse/langfuse/pull/15298
• fix(agent): Instrument user info on in-app agent requests by @bezbac in https://github.com/langfuse/langfuse/pull/15317
• fix(otel): decode Python bytes media by @hassiebp in https://github.com/langfuse/langfuse/pull/15347
• fix(filter-sidebar): always show Clear when a filter is active (LFE-14402) by @nkabardin in https://github.com/langfuse/langfuse/pull/15314
• fix(chatml): render Google ADK invocation root spans as chat messages by @milanagm in https://github.com/langfuse/langfuse/pull/15299
• fix: remove all dataset run reads from v4 path by @marliessophie in https://github.com/langfuse/langfuse/pull/15222
• fix(search): don't apply incomplete filter tokens to the query (LFE-11017) by @nkabardin in https://github.com/langfuse/langfuse/pull/15315
• fix(nav): close the mobile nav drawer when navigation starts (LFE-11067) by @nkabardin in https://github.com/langfuse/langfuse/pull/15327
• fix(layouts): mobile page header no longer crushes the title with its actions (LFE-11067) by @nkabardin in https://github.com/langfuse/langfuse/pull/15325
• fix(search-bar): placeholder no longer runs under Ask AI on narrow widths by @nkabardin in https://github.com/langfuse/langfuse/pull/15323
• fix(chart-view): make Visualize panel responsive on mobile (LFE-11067) by @nkabardin in https://github.com/langfuse/langfuse/pull/15326
• fix(evals): support Sonnet 5 on Bedrock by @hassiebp in https://github.com/langfuse/langfuse/pull/15375
• fix(otel): process legacy media and classify data uris by @hassiebp in https://github.com/langfuse/langfuse/pull/15353
• fix(observability): re-enable Sentry source-map upload w/ debug IDs (LFE-14423) by @nkabardin in https://github.com/langfuse/langfuse/pull/15324

Chores

• chore(pricing): add gemini-3.6-flash and gemini-3.5-flash-lite pricing by @langfuse-bot in https://github.com/langfuse/langfuse/pull/15285
• revert(deploy): remove ECS task_arn DD_TAGS tagging (LFE-11028) by @niklassemmler in https://github.com/langfuse/langfuse/pull/15335
• chore(pricing): remove invalid cache pricing from gemini-3.5-flash-lite by @langfuse-bot in https://github.com/langfuse/langfuse/pull/15340
• chore(deps): bump fast-uri to 3.1.4 by @nimarb in https://github.com/langfuse/langfuse/pull/15355
• chore(deps): bump @vitest/browser to 4.1.10 by @nimarb in https://github.com/langfuse/langfuse/pull/15356
• chore(deps): bump next to 16.2.11 by @nimarb in https://github.com/langfuse/langfuse/pull/15358
• chore(deps): bump turbo to 2.10.5 by @nimarb in https://github.com/langfuse/langfuse/pull/15360
• chore(deps): bump hono to 4.12.27 by @nimarb in https://github.com/langfuse/langfuse/pull/15363
• chore(deps): bump dompurify to 3.4.12 by @nimarb in https://github.com/langfuse/langfuse/pull/15364
• refactor(web): Cleanup Progress component by @bezbac in https://github.com/langfuse/langfuse/pull/15366
• ci(observability): register Sentry release + deploy marker on prod deploy (LFE-14421) by @nkabardin in https://github.com/langfuse/langfuse/pull/15320
• chore: align metadata values index names with prod by @Steffen911 in https://github.com/langfuse/langfuse/pull/15371
• build: remove pg 12 from CI and pin CH to 25.12 in docker-compose by @Steffen911 in https://github.com/langfuse/langfuse/pull/15376

Full Changelog: https://github.com/langfuse/langfuse/compare/v3.224.0...v4.0.0-rc.0