{"type":"post","slug":"langfuse-v4-cli-and-evaluator-templates","title":"Langfuse v4, CLI and evaluator templates","description":"Langfuse v4 makes every LLM call, tool execution and agent step directly queryable, with table loads dropping from seconds to milliseconds and a hard Cloud cutover in November.","retrieval_nugget":"Langfuse v4 makes every LLM call, tool execution and agent step directly queryable, with table loads dropping from seconds to milliseconds and a hard Cloud cutover in November.","published_at":"2026-08-31","updated_at":"2026-09-12","record_date":"2026-08-17","date_kind":"published_at","topics":["agent-integrations","agents","ai"],"entities":["Langfuse"],"source_url":"https://langfuse.com/changelog/2026-08-17-langfuse-v4","source_title":"Langfuse v4 is live: faster at scale, with more ways to search, monitor, and evaluate - Langfuse","source_domain":"langfuse.com","source_terms":["Langfuse","evaluator","templates","faster","Cloud"],"summary_word_count":199,"schema_version":"newruntime-agent-readable-v0.2","stable_id":"post:langfuse-v4-cli-and-evaluator-templates","status":"published","source_urls":["https://langfuse.com/changelog/2026-08-17-langfuse-v4"],"visuals":[],"editorial_provenance":{"schema_version":"newruntime-editorial-copy-v1","content_status":"source_grounded_final","final_copy_sha256":"sha256:6bae11d52029569242772551e5fbc7f94b714f49c2c216871ae18d64292ad717","reviewed_at":"2026-09-12T10:00:00Z","source_evidence_count":1,"verified_claim_count":2,"site_analysis_schema_version":"newruntime-site-analysis-v1","site_object_kind":"field_note","observed_fact_count":2,"implication_count":1,"watch_condition_count":1,"related_record_count":3},"analysis":{"schema_version":"newruntime-site-analysis-v1","object_kind":"field_note","thesis":"Langfuse v4 went live on Langfuse Cloud and generally available for self-hosted deployments on 17 August.","observed_facts":[{"text":"Langfuse v4 is live on Langfuse Cloud and generally available for self-hosted deployments.","source_urls":["https://langfuse.com/changelog/2026-08-17-langfuse-v4"]},{"text":"Langfuse Cloud becomes v4-only on 16 November 2026, with a Migration Assistant listing per-project actions.","source_urls":["https://langfuse.com/changelog/2026-08-17-langfuse-v4"]}],"mechanism":"every LLM call, tool execution and agent step becomes directly queryable and evaluable, rather than reachable only through a trace view: initial table loads over large datasets drop from seconds to milliseconds, and dashboards over longer time ranges load at least ten times faster in large projects","why_now":"Langfuse Cloud becomes v4-only on 16 November 2026; most projects need no migration, but a Migration Assistant surfaces per-project actions that must be completed before that date, and self-hosted operators are told to plan the upgrade and review infrastructure requirements first.","implications":["Making the agent step the queryable unit is what turns observability into a diagnostic rather than a record"],"evidence_boundary":"The performance figures are the vendor's own and stated as ranges for large projects rather than a published benchmark.","watch_conditions":["The condition to watch is whether step-level querying makes evaluator results comparable across versions, because faster dashboards over the same ambiguous step boundaries would improve latency without improving diagnosis."],"related_records":[{"url":"https://newruntime.com/posts/evals-move-from-leaderboards-to-operating-diagnostics","relation":"Prior coverage of evaluation becoming an operating diagnostic."},{"url":"https://newruntime.com/posts/agent-operations-are-converging-on-connectors-memory-observability-dashboard","relation":"Prior coverage of the agent operations control plane."},{"url":"https://newruntime.com/topics/agents","relation":"Topic hub for agent observability."}]},"routes":{"html":"https://newruntime.com/posts/langfuse-v4-cli-and-evaluator-templates/","markdown":"https://newruntime.com/posts/langfuse-v4-cli-and-evaluator-templates.md","json":"https://newruntime.com/posts/langfuse-v4-cli-and-evaluator-templates.json"},"editor":{"role":"editor","name":"Andrey Reshetnikov","profile":"https://newruntime.com/owner-profile.md","profile_json":"https://newruntime.com/owner-profile.json","same_as":["https://www.linkedin.com/in/reshetnikov1/","https://t.me/lapetuse"]},"next_reads":[{"type":"topic","path":"/topics/agent-integrations/","url":"https://newruntime.com/topics/agent-integrations/","title":"Agent Integrations","reason":"Explore the agent-integrations topic hub.","media_type":"text/html","markdown_url":"https://newruntime.com/topics/agent-integrations.md","json_url":"https://newruntime.com/topics/agent-integrations.json"},{"type":"topic","path":"/topics/agents/","url":"https://newruntime.com/topics/agents/","title":"Agents","reason":"Explore the agents topic hub.","media_type":"text/html","markdown_url":"https://newruntime.com/topics/agents.md","json_url":"https://newruntime.com/topics/agents.json"},{"type":"topic","path":"/topics/ai/","url":"https://newruntime.com/topics/ai/","title":"Ai","reason":"Explore the ai topic hub.","media_type":"text/html","markdown_url":"https://newruntime.com/topics/ai.md","json_url":"https://newruntime.com/topics/ai.json"},{"type":"collection","path":"/posts/","url":"https://newruntime.com/posts/","title":"Field Notes","reason":"Open the latest editorial analysis.","media_type":"text/html","json_url":"https://newruntime.com/posts.json"},{"type":"collection","path":"/source-ledger.json","url":"https://newruntime.com/source-ledger.json","title":"Source Ledger","reason":"Inspect the public source evidence graph.","media_type":"application/json"}]}