session/prompt fails silently when session limit is reached

[xenodium]

Hi folks! Thank you for building claude-code-acp. Big fan. It's been working great with agent-shell. From time to time, I run into a snag...

When Claude Code's Session limit is reached for the current subscription, the session/prompt request fails silently. That is, stopReason is end_turn and no output givent. There are no errors reported anywhere, as far as I can see (including stderr). Should I be looking elsewhere, so I can surface this issue to users?

Below is the entire exchange between agent-shell and claude-code-acp, including a tiny bit of stderr. Lemme know if there's anything else I can provide.

initialize

{
  "jsonrpc": "2.0",
  "method": "initialize",
  "id": 1,
  "params": {
    "protocolVersion": 1,
    "clientCapabilities": {
      "fs": {
        "readTextFile": true,
        "writeTextFile": true
      }
    }
  }
}

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "protocolVersion": 1,
    "agentCapabilities": {
      "promptCapabilities": {
        "image": true,
        "embeddedContext": true
      },
      "mcpCapabilities": {
        "http": true,
        "sse": true
      }
    },
    "agentInfo": {
      "name": "@zed-industries/claude-code-acp",
      "title": "Claude Code",
      "version": "0.10.0"
    },
    "authMethods": [
      {
        "description": "Run `claude /login` in the terminal",
        "name": "Log in with Claude Code",
        "id": "claude-login"
      }
    ]
  }
}

session/new

{
  "jsonrpc": "2.0",
  "method": "session/new",
  "id": 2,
  "params": {
    "cwd": "path/to/project/dir/",
    "mcpServers": []
  }
}

Spawning Claude Code process: /opt/homebrew/Cellar/node/24.8.0/bin/node /opt/homebrew/lib/node_modules/@zed-industries/claude-code-acp/node_modules/@anthropic-ai/claude-agent-sdk/cli.js --output-format stream-json --verbose --input-format stream-json --permission-prompt-tool stdio --allowedTools mcp__acp__Read --disallowedTools Read,Write,Edit --mcp-config {"mcpServers":{"acp":{"type":"sdk","name":"acp"}}} --setting-sources user,project,local --permission-mode default --allow-dangerously-skip-permissions --include-partial-messages

{
  "jsonrpc": "2.0",
  "id": 2,
  "result": {
    "sessionId": "019a5e9b-8ff5-711f-ba7b-23a10043da78",
    "models": {
      "availableModels": [
        {
          "modelId": "default",
          "name": "Sonnet",
          "description": "Sonnet 4.5 · Smartest model for daily use · $3/$15 per Mtok"
        },
        {
          "modelId": "haiku",
          "name": "Haiku",
          "description": "Haiku 4.5 · Fastest model for simple tasks"
        }
      ],
      "currentModelId": "default"
    },
    "modes": {
      "currentModeId": "default",
      "availableModes": [
        {
          "id": "default",
          "name": "Always Ask",
          "description": "Prompts for permission on first use of each tool"
        },
        {
          "id": "acceptEdits",
          "name": "Accept Edits",
          "description": "Automatically accepts file edit permissions for the session"
        },
        {
          "id": "plan",
          "name": "Plan Mode",
          "description": "Claude can analyze but not modify files or execute commands"
        },
        {
          "id": "bypassPermissions",
          "name": "Bypass Permissions",
          "description": "Skips all permission prompts"
        }
      ]
    }
  }
}

{
  "jsonrpc": "2.0",
  "method": "session/update",
  "params": {
    "sessionId": "019a5e9b-8ff5-711f-ba7b-23a10043da78",
    "update": {
      "sessionUpdate": "available_commands_update",
      "availableCommands": [
        {
          "name": "compact",
          "description": "Clear conversation history but keep a summary in context. Optional: /compact [instructions for summarization]",
          "input": {
            "hint": "<optional custom summarization instructions>"
          }
        },
        {
          "name": "init",
          "description": "Initialize a new CLAUDE.md file with codebase documentation",
          "input": null
        },
        {
          "name": "pr-comments",
          "description": "Get comments from a GitHub pull request",
          "input": null
        },
        {
          "name": "review",
          "description": "Review a pull request",
          "input": null
        },
        {
          "name": "security-review",
          "description": "Complete a security review of the pending changes on the current branch",
          "input": null
        }
      ]
    }
  }
}

session/prompt

{
  "jsonrpc": "2.0",
  "method": "session/prompt",
  "id": 3,
  "params": {
    "sessionId": "019a5e9b-8ff5-711f-ba7b-23a10043da78",
    "prompt": [
      {
        "type": "text",
        "text": "hello"
      }
    ]
  }
}

{
  "jsonrpc": "2.0",
  "id": 3,
  "result": {
    "stopReason": "end_turn"
  }
}

[benbrandt]

Hmm I wonder if compaction is happening so it doesn't complete a turn while that is happening? we need to probably surface the compaction step