Direct API vs. Subscription for Multi-Agent Coding (DeepSeek)? Burning quotas fast, suspecting KV cache misses

TL;DR: Running up to 10 parallel sub-agents across 2 machines using OpenCode CLI, Hermes Agent, etc. I’m burning through my OpenCode subscription quota way faster than expected. I suspect prefix caching (Radix tree) is failing due to concurrency/routing. Assuming the same budget, is DeepSeek direct API better? Looking for provider and harness recommendations. --- My Current Setup & Workflow - 2 PCs firing requests concurrently - Up to 10 sub-agents working in parallel (breaking down implementation phases and assigning tasks to separate agents) - Harnesses / Tools: OpenCode CLI, Hermes Agent, Codex - Current Plan: DeepSeek v4.1 via OpenCode subscription The Problem My quota is getting eaten up ridiculously fast. My working hypothesis is that running parallel agents from two different machines through the subscription proxy causes load-balancing cache evictions or prefix mismatches. Instead of hitting cached tokens (90% discount), I might be paying full context costs on nearly every call. Questions: Direct API vs. Subscription: Given the same monthly budget, would switching directly to DeepSeek's official API (\api.deepseek.com) be drastically more cost-effective for multi-agent workloads due to native automatic prefix caching? Provider & Routing for Concurrency: What provider setup best handles \~10 concurrent agents across 2 PCs without constantly invalidating KV cache? (Direct API, OpenRouter with sticky routing, or something else?) Best Agent Harness for Cache Preservation: Which CLI/harness (Aider, OpenCode CLI, Hermes Agent, etc.) does the best job of keeping the root prompt prefix consistent across parallel agent runs so the Radix tree actually hits? Alternative Models/Providers: Besides DeepSeek, what providers/models offer robust Radix tree / prefix caching with great price-to-performance for vibe coding? Would love to hear how anyone running heavy multi-agent / parallel coding pipelines manages their cache and infra on budget. Thanks!