Core stall: With `HALOGEN_FLASH_PIN_TRUNK=1`, co-tenant can stall engine for minutes. Last resort: `HALOGEN_FLASH_PIN_TRUNK=0`. First request after restart may be silent ~45-60s. `frank-large` `maxTokens` must be <=65536. Prompt + max_tokens must fit KV pool or queue ~3600s then 503s.