Manifest describes why it deprecated the LLM router it ran for four months across 7000 users

Sources: primary, discussion
Summary: Manifest launched the router in March 2026 and deprecated it in June 2026 after running it across 7000 users. The write-up is what is new, and it argues that prompt text does not carry the task complexity discovered later through tool calls, and that prefix cache reads priced at 75 to 90 percent off make model stickiness cheaper than switching. The router shuts down for good on 2026-09-01.
Why it matters: Both arguments are checkable by any team building routing in front of multiple models, and they come from a vendor arguing against its own shipped feature.
Follow-up: Check that the router shutdown lands on 2026-09-01 for teams still calling it.