Connect Claude Code or Codex

HikariSub can serve your open files to an AI agent you run yourself, such as Claude Code or Codex, over the Model Context Protocol (MCP). The agent reads the open files and can edit them. Every edit it makes waits in the Review panel until you keep or undo it.

The agent works with its own AI account. HikariSub's MCP server doesn't use a provider of its own.

Before you startCopy Anchor Link

• HikariSub is running, with the files you want the agent to see open.
• AI features are on. With Turn off all AI features ticked in File › Settings › AI, the MCP section isn't shown and no server runs.
• HikariSub's AI component is on this computer. The MCP server runs through it. It downloads with your first provider: if you haven't added one in File › Settings › AI, add one first.

Turning on the MCP serverCopy Anchor Link

1. Open File › Settings › AI, and in the MCP section tick Let agents outside HikariSub edit through MCP. It is off at first.
2. Press OK or Apply. HikariSub starts listening, on this computer only.

The rows below the box, Also listen on http://127.0.0.1 and Copy setup, show once it is ticked.

Connecting Claude CodeCopy Anchor Link

1. In the MCP section, choose Copy setup › Claude Code command. The page says Copied. Run it in a terminal.

2. Run it in a terminal. It looks like this, with the path of your HikariSub, or of its AppImage:

   Copy Text

   claude mcp add hikari -- "/path/to/hikarisub" --mcp

3. Start Claude Code. It starts hikarisub --mcp, which connects it to the HikariSub that is running.

Connecting CodexCopy Anchor Link

1. Choose Copy setup › Codex config.toml. The page says Copied. Paste it into the agent's settings.

2. Paste it into Codex's config.toml:

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   [mcp_servers.hikari]
   command = "/path/to/hikarisub"
   args = ["--mcp"]

3. Start Codex.

Other agentsCopy Anchor Link

An agent that starts a program can use the same command: HikariSub's path, with --mcp.

For an agent that connects over HTTP:

1. Tick Also listen on http://127.0.0.1, and press OK or Apply. The row then shows the port, such as http://127.0.0.1:41234. HikariSub keeps the same port after a restart, unless another program has taken it.
2. Choose Copy setup › JSON with the address and token, and paste it into the agent's settings. The entry is greyed out until HikariSub listens.

The JSON holds a token, which lets anything that has it edit your open files through HikariSub. Keep it private: don't share it, or put it in a file others can read. Only this computer can reach the address, and only with the token.

What the agent can doCopy Anchor Link

• Read every open file: its lines, styles and script properties, and HikariSub's AI tools.
• Edit in only one way, by applying an edit to a file. HikariSub refuses everything else an agent asks to change. Each edit goes into the file at once, and waits in the Review panel under a turn named after the agent, such as Claude Code. Each connection gets turns of its own.

Nothing in HikariSub shows that an agent is connected: you see it by its edits.

The agent's toolsCopy Anchor Link

The agent gets the same tools HikariSub's AI uses: reading and searching lines, styles and the video, such as a frame of the video with one line drawn on it. It sees every tool at once.

If the agent can't connectCopy Anchor Link

The agent shows what hikarisub --mcp said:

• HikariSub isn't running with its MCP server on. Start HikariSub, turn the MCP server on in Settings > AI, then connect again. Check that HikariSub is running, that the box is ticked and applied, and that Turn off all AI features is off.
• HikariSub's AI sidecar isn't installed; install it in Settings > AI. Add a provider in File › Settings › AI, which downloads the AI component.

Turning it offCopy Anchor Link

Clear Let agents outside HikariSub edit through MCP, and press OK or Apply. HikariSub stops listening, and connected agents are cut off. Turn off all AI features stops it too.

What HikariSub sends for its MCP server, and what it doesn't, is in What is sent.