Zed

Zed introduced Agent Client Protocol in August 2025: JSON-RPC 2.0 over stdio, Apache-2.0, doing for coding agents what LSP did for languages. Where N editors and M agents once required N×M bespoke integrations, N+M now suffices. The protocol has since moved out of its creator's orbit, acquiring its own organization, an agent registry, a versioned specification, and a JetBrains implementation.

What keeps bringing Zed back into view is pricing rather than interoperability. On 14 May 2026, Franciska Dethlefsen, head of growth and marketing, wrote that Anthropic would split Claude subscription billing on 15 June: first-party tools (chat, the official Claude Code CLI) on one side, third-party agent and SDK usage on the other, including anything going through ACP. The separate Agent SDK credit was set at $20 for Pro, $100 for Max 5x, $200 for Max 20x, billed at full API rates, against subscriptions that had been subsidising agentic usage by roughly 15 to 30×, a figure attributed to engineer Matthew Diakonov. Zed's recommended escape was to run the official `claude` CLI in a terminal inside the editor, where subscription limits still applied. The same post announced Terminal Threads and stated the underlying position: an open protocol keeps an editor from being locked into one provider's pricing decisions.

Anthropic suspended the change on 16 June, the day it was to take effect, so the regime Zed analysed never existed. Zed's expectation that this kind of change will recur remains untested.