How to Make a Control Plane for Coding Agents in 2026

Every tool does the same three things

Job 1 is where the products differ. Three ways to speak to an agent, and each one caps what the screen can ever show. The quickest way to see it: the same edit, one line in src/billing.ts, as it arrives each way.

A PTY is a pseudo-terminal. A fake terminal a program runs inside, so the program thinks a person is typing. The product launches the ordinary CLI, the one you'd run yourself, inside a PTY, types the prompt in, and reads the text that comes out. A person at a keyboard, except the person is a program.

● Update(src/billing.ts)
     12 -  const rate = 0.2
     12 +  const rate = 0.25
no prompt: --dangerously-skip-permissions

ACP is Zed's protocol. JSON-RPC over stdio, one wire format for start a session, send a prompt, get updates, answer permissions. Gemini, OpenCode, Cursor CLI, Copilot CLI, Kiro, Factory Droid, Devin's CLI and DeepSeek's harness speak it natively. Claude Code and Codex don't. They get there through adapters, claude-agent-acp and codex-acp, separate processes that run the native driver underneath.

session/update  tool_call
  call_7  kind: edit  status: pending
  locations: [ src/billing.ts ]
  content: [ diff … ]   if the adapter fills it
session/request_permission → allow_once
session/update  tool_call_update  call_7  completed
no usage · no subagent kind · nothing in between

Each agent has a machine interface its own vendor's products use. Claude Code: the Agent SDK runs the loop in your process, hands you every event, asks you through a callback before each tool. Codex: the app-server, a JSON-RPC process with thread and turn methods, item lifecycle notifications, approval requests per kind. OpenCode: a server with sessions, an SSE stream, permissions, questions. Pi: an RPC mode over its terminal with prompt, steer, follow-up, abort, fork.

canUseTool("Edit", input) → allow
tool_use  Edit  toolu_01
  file_path:  src/billing.ts
  old_string: const rate = 0.2
  new_string: const rate = 0.25
tool_result  toolu_01  updated
result  session_id: ses_9f2  cost_usd: 0.0123

What the screen can draw from each

Scroll to compare →   Row labels stay in view.

The middle column is the one that surprises people. ACP looks like data and mostly is. What it costs is the three rows a control plane exists for: resume, approvals that mean what the agent meant, and knowing what is running. For an agent that speaks nothing else, ACP is the right door. For Claude and Codex it is a second door to an agent you can already reach.

The Rust way: Waku

Every other product here is TypeScript. So are the agents' own client libraries: the Claude Agent SDK is a Node package, OpenCode's SDK is TypeScript, T3's Codex driver is a TypeScript port of the app-server schema. Waku is Rust end to end. A daemon, a GPUI desktop app, a protocol crate. That one choice changes how all three jobs get done.

Every other product here is TypeScript, like the agents' own client libraries. Waku is Rust end to end: a daemon, a GPUI desktop app, a protocol crate. So its vocabulary is a Rust enum, not a schema. Every driver must produce it and every consumer must match it exhaustively; add a variant and the daemon and the app fail to compile until both handle it.

The protocol types carry a TS derive. ts-rs generates the TypeScript from them into the client package, and the web and mobile apps import it. Daemon, native app, browser and phone share one definition of a session, an activity, a permission. Codex's app-server protocol is Rust with ts-rs bindings of its own, so Waku speaks it type to type; Claude has no Rust library, so Waku speaks its stream-json wire directly, no Node sidecar.

The screen is the point: "staying smooth under a long transcript on a high-refresh display is the point of being native." A virtualized GPUI list, drivers feeding a channel the frame loop drains. What it leaves out is everything multi-user: one token, SQLite and git refs as the record, no organization.

The vocabulary they share

Whichever way an agent is spoken to, what comes out is folded into the same nouns. Read across a row and you are reading translations.

Scroll to compare →   Row labels stay in view.

Tool calls fall into the same eight families everywhere: read, edit or write, execute, search, fetch, plan, subagent, other. ACP names them in the spec; the others classify by the tool's name.

Keeping the record

Most tools translate on the way in and keep only the translation. On one laptop that's fine, the agent's own transcript on disk is the raw copy. A hosted product doesn't have that transcript. The sandbox that wrote it is gone. So it has to keep its own.

Most tools translate on the way in and keep only the translation. On one laptop that's fine, the agent's own transcript on disk is the raw copy. A hosted product doesn't have that transcript. The sandbox that wrote it is gone. So it keeps its own: the event exactly as the agent sent it, then the vocabulary derived from that. The translator is the piece most likely to be wrong, because the agents change weekly, and with the raw copy kept a fix is a re-run over history instead of a permanent hole.

Emdash keeps nothing and re-asks the agent. Paseo keeps rows in memory. Waku keeps SQLite and a resume cursor. T3 keeps an event store. A hosted control plane keeps the raw frame and the translation, sealed per run, scoped to an organization.

Seven products, side by side

Read each column top to bottom. The driver row decides everything under it.

Scroll to compare →   Row labels stay in view.

About the author

I build UseAgent, the hosted one in the last column: the four agents in cloud workstations, one timeline, scoped to a company. It runs on T3 Code's runtime and grammar, because T3 already spoke the native protocols and its event core is the right seam. UseAgent keeps the raw frame T3 hands over and translates it again for the record.

Sources

• Agent Client Protocol · agentclientprotocol.com · github
• Claude Code · code.claude.com/docs · github
• Codex · learn.chatgpt.com/docs · github
• OpenCode · opencode.ai/docs · github
• Pi · github
• Cursor · cursor.com/docs/cli
• Orca · onorca.dev · github
• Superset · superset.sh · github
• Emdash · emdash.com · github
• Paseo · paseo.sh · github
• Waku · waku.sh · github
• T3 Code · github
• UseAgent · useagent.org · github