feat: config-driven architecture, install wizard, live runtime switching, usage tracking, auto-failover

Major changes:
- Config-driven adapters: all channels (Slack, Discord, Telegram, WebChat, Webhooks) controlled via config.json with enabled flags and token auto-detection, no CLI flags required
- Runtime engine field: runtime.engine selects opencode/claude from config
- Interactive install script: 8-phase setup wizard with AI runtime detection/installation, token setup, identity file personalization (personality presets), aetheel CLI command, background service (launchd/systemd)
- Live runtime switching: /engine, /model, /provider commands hot-swap the AI runtime from chat without restart, changes persisted to config.json
- Usage tracking: per-request cost extraction from Claude Code JSON output, cumulative stats via /usage command
- Auto-failover: rate limit detection on both runtimes, automatic switch to other engine on quota errors with user notification
- Chat commands work without / prefix (Slack intercepts / in channels), commands: engine, model, provider, config, usage, reload, cron, subagents, status, help
- /config set for editing config.json from chat with dotted key notation
- Security audit saved to docs/security-audit.md
- Full command reference in docs/commands.md
- Future changes doc with NanoClaw agent teams analysis
- Logo added to README and WebChat UI
- README fully rewritten with all features documented

tests/test_mcp_config.py

@@ -0,0 +1,134 @@
+"""
+Tests for the MCP config writer utility (write_mcp_config).
+"""
+
+import json
+import os
+
+import pytest
+
+from config import MCPConfig, MCPServerConfig, write_mcp_config
+
+
+# ---------------------------------------------------------------------------
+# Fixtures
+# ---------------------------------------------------------------------------
+
+
+@pytest.fixture
+def workspace(tmp_path):
+    """Return a temporary workspace directory path."""
+    return str(tmp_path)
+
+
+@pytest.fixture
+def sample_mcp_config():
+    """Return an MCPConfig with one server entry."""
+    return MCPConfig(
+        servers={
+            "my-tool": MCPServerConfig(
+                command="npx",
+                args=["-y", "@my/tool"],
+                env={"API_KEY": "test123"},
+            )
+        }
+    )
+
+
+# ---------------------------------------------------------------------------
+# Tests: write_mcp_config
+# ---------------------------------------------------------------------------
+
+
+class TestWriteMcpConfig:
+    def test_skips_when_no_servers(self, workspace):
+        """Empty servers dict should not create any file."""
+        write_mcp_config(MCPConfig(), workspace, use_claude=True)
+        assert not os.path.exists(os.path.join(workspace, ".mcp.json"))
+        assert not os.path.exists(os.path.join(workspace, "opencode.json"))
+
+    def test_writes_mcp_json_for_claude(self, workspace, sample_mcp_config):
+        """Claude runtime should produce .mcp.json with 'mcpServers' key."""
+        write_mcp_config(sample_mcp_config, workspace, use_claude=True)
+        path = os.path.join(workspace, ".mcp.json")
+        assert os.path.isfile(path)
+
+        with open(path, encoding="utf-8") as f:
+            data = json.load(f)
+
+        assert "mcpServers" in data
+        assert "my-tool" in data["mcpServers"]
+        srv = data["mcpServers"]["my-tool"]
+        assert srv["command"] == "npx"
+        assert srv["args"] == ["-y", "@my/tool"]
+        assert srv["env"] == {"API_KEY": "test123"}
+
+    def test_writes_opencode_json_for_opencode(self, workspace, sample_mcp_config):
+        """OpenCode runtime should produce opencode.json with 'mcp' key."""
+        write_mcp_config(sample_mcp_config, workspace, use_claude=False)
+        path = os.path.join(workspace, "opencode.json")
+        assert os.path.isfile(path)
+
+        with open(path, encoding="utf-8") as f:
+            data = json.load(f)
+
+        assert "mcp" in data
+        assert "my-tool" in data["mcp"]
+
+    def test_multiple_servers(self, workspace):
+        """Multiple server entries should all appear in the output."""
+        cfg = MCPConfig(
+            servers={
+                "server-a": MCPServerConfig(command="cmd-a", args=["--flag"]),
+                "server-b": MCPServerConfig(command="cmd-b", env={"X": "1"}),
+            }
+        )
+        write_mcp_config(cfg, workspace, use_claude=True)
+
+        with open(os.path.join(workspace, ".mcp.json"), encoding="utf-8") as f:
+            data = json.load(f)
+
+        assert len(data["mcpServers"]) == 2
+        assert "server-a" in data["mcpServers"]
+        assert "server-b" in data["mcpServers"]
+
+    def test_creates_parent_directories(self, tmp_path):
+        """Should create intermediate directories if workspace doesn't exist."""
+        nested = str(tmp_path / "deep" / "nested" / "workspace")
+        cfg = MCPConfig(
+            servers={"s": MCPServerConfig(command="echo")}
+        )
+        write_mcp_config(cfg, nested, use_claude=True)
+        assert os.path.isfile(os.path.join(nested, ".mcp.json"))
+
+    def test_produces_valid_json(self, workspace, sample_mcp_config):
+        """Output file must be valid, parseable JSON."""
+        write_mcp_config(sample_mcp_config, workspace, use_claude=True)
+        path = os.path.join(workspace, ".mcp.json")
+        with open(path, encoding="utf-8") as f:
+            data = json.load(f)  # Would raise on invalid JSON
+        assert isinstance(data, dict)
+
+    def test_overwrites_existing_file(self, workspace):
+        """Writing twice should overwrite the previous config."""
+        cfg1 = MCPConfig(servers={"old": MCPServerConfig(command="old-cmd")})
+        cfg2 = MCPConfig(servers={"new": MCPServerConfig(command="new-cmd")})
+
+        write_mcp_config(cfg1, workspace, use_claude=True)
+        write_mcp_config(cfg2, workspace, use_claude=True)
+
+        with open(os.path.join(workspace, ".mcp.json"), encoding="utf-8") as f:
+            data = json.load(f)
+
+        assert "new" in data["mcpServers"]
+        assert "old" not in data["mcpServers"]
+
+    def test_tilde_expansion(self, monkeypatch, tmp_path):
+        """Workspace path with ~ should be expanded."""
+        monkeypatch.setenv("HOME", str(tmp_path))
+        # Also handle Windows
+        monkeypatch.setattr(os.path, "expanduser", lambda p: p.replace("~", str(tmp_path)))
+
+        cfg = MCPConfig(servers={"s": MCPServerConfig(command="echo")})
+        write_mcp_config(cfg, "~/my-workspace", use_claude=False)
+        assert os.path.isfile(os.path.join(str(tmp_path), "my-workspace", "opencode.json"))