Agent config panel lists MCP servers from hardcoded ~/.claude.json, ignoring per-agent CLAUDE_CONFIG_DIR

[oshnilia]

Describe the bug

When a managed agent is given its own CLAUDE_CONFIG_DIR (via Agents → Agent defaults, or per-agent env vars) in order to isolate it from the operator's personal Claude Code configuration, the agent config panel still lists the MCP servers from the operator's ~/.claude.json and labels them "mcp enabled". The list is identical for every agent regardless of that agent's environment.

The runtime itself is isolated — only the panel is wrong. But the panel is the only place an operator can check, so it reads as "the isolation did not work", which is alarming when the personal config contains mail/drive/database connectors.

Steps to reproduce

1. Have one or more MCP servers configured at user scope in ~/.claude.json.
2. Create an isolated config dir, e.g. <nest>/claude-config, containing .claude.json with {"mcpServers": {}} and settings.json with {"disableClaudeAiConnectors": true}; authenticate it once with CLAUDE_CONFIG_DIR=<nest>/claude-config claude auth login.
3. Set CLAUDE_CONFIG_DIR=<nest>/claude-config in Agent defaults (or per-agent env vars) and restart the agents.
4. Open the config panel for any agent.

Expected behavior

The MCP Servers section reflects the configuration the agent will actually load — empty for an isolated agent — and the "From config file (…)" attribution points at that file.

Actual behavior

The section lists every server from the operator's ~/.claude.json.

Independent checks confirming the runtime is genuinely isolated:

• ps eww on buzz-acp and on its claude-agent-acp child both show CLAUDE_CONFIG_DIR=<nest>/claude-config
• CLAUDE_CONFIG_DIR=<nest>/claude-config claude mcp list → No MCP servers configured
• asking the agent to list tools named mcp__* → none

Cause

desktop/src-tauri/src/managed_agents/config_bridge/claude.rs:

pub(super) fn read_config_file() -> Option<RuntimeFileConfig> {
    let home = dirs::home_dir()?;
    let settings_path = home.join(".claude").join("settings.json");
    let mcp_path = home.join(".claude.json");

The path is derived from $HOME unconditionally; the agent's effective environment (global / persona / per-agent env_vars) is never consulted. The same applies to the attribution path in config_bridge/reader.rs:

"claude" => Some(resolve_tilde("~/.claude.json")),

Code path is unchanged on main at the time of writing.

Suggested fix

Resolve the Claude config directory from the agent's effective env — CLAUDE_CONFIG_DIR when set, ~/.claude otherwise — and pass it into read_config_file(), so both the MCP list and the "From config file (…)" attribution describe the file the agent will actually read. Honoring disableClaudeAiConnectors from the resolved settings.json when rendering the list would make the panel accurate for account-scoped claude.ai connectors too.

Version and platform

• Buzz version: 0.4.26
• OS: macOS 26.5.2
• Runtime: claude / @agentclientprotocol/claude-agent-acp 0.62.0