session/resume. Same as session/load but without message replaying

[molecule-man]

Problem

• session/load mandates that "The Agent MUST replay the entire conversation to the Client" (see docs)
• not all agents support the replaying part. For instance claude code does not.

Proposal

Add session/resume which will be clone of session/load but without the message replaying part. This could enable solving issues like zed-industries/claude-code-acp#130.

Checking support:

{
  "jsonrpc": "2.0",
  "id": 0,
  "result": {
    "protocolVersion": 1,
    "agentCapabilities": {
      "resumeSession": true
    }
  }
}

resuming:

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "session/resume",
  "params": {
    "sessionId": "sess_789xyz",
    "cwd": "/home/user/project",
    "mcpServers": [
      {
        "name": "filesystem",
        "command": "/path/to/mcp-server",
        "args": ["--mode", "filesystem"],
        "env": []
      }
    ]
  }
}

[benbrandt]

Let's consolidate discussion on this to the current proposed RFD #234