feat: Implement ADR-004 Progressive Consent foundation (partial)
Implements Progressive Consent architecture with dual OAuth flows: - Flow 1: Direct client authentication (aud: "mcp-server") - Flow 2: Resource provisioning with refresh tokens Components added: - Client registry with validation (client_registry.py) - Progressive token verifier (progressive_token_verifier.py) - Token broker service integration - Provisioning decorator for MCP tools - OAuth provisioning tools (provision_nextcloud_access, etc.) Configuration: - Progressive Consent enabled by default (ENABLE_PROGRESSIVE_CONSENT=true) - Client validation with pre-registered clients - Audience separation framework KNOWN ISSUE - Token Exchange Pattern Incorrect: The current implementation does NOT properly implement token exchange. MCP session tokens should be EXCHANGED for delegated Nextcloud tokens during tool calls, not stored/reused. Critical corrections needed: 1. Session tokens: Flow 1 token → exchange → ephemeral Nextcloud token - Generated on-demand per tool call - Short-lived, not stored - Scopes limited to tool requirements 2. Background tokens: Flow 2 refresh token → background Nextcloud token - Only for offline/background jobs - Potentially different scopes than session tokens - Must NOT be used for MCP session tool calls The token exchange mechanism needs to be implemented to properly separate session-time delegation from background job authorization. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>
This commit is contained in:
Chris Coutinho
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"""
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MCP Client Registry for ADR-004 Progressive Consent Architecture.
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This module manages the registry of allowed MCP clients that can authenticate
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via Flow 1. In production, this would integrate with Dynamic Client Registration
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(DCR) or a database of pre-registered clients.
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"""
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import logging
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import os
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from dataclasses import dataclass
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from typing import Dict, List, Optional
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logger = logging.getLogger(__name__)
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@dataclass
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class MCPClientInfo:
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"""Information about a registered MCP client."""
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client_id: str
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name: str
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redirect_uris: List[str]
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allowed_scopes: List[str]
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is_public: bool = True # Native clients are public (no client_secret)
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metadata: Optional[Dict] = None
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class ClientRegistry:
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"""
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Registry for MCP clients allowed to authenticate via Flow 1.
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In production, this would:
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1. Support Dynamic Client Registration (DCR) per RFC 7591
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2. Integrate with IdP client registry
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3. Store client metadata in database
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4. Support client updates and revocation
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"""
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def __init__(self, allow_dynamic_registration: bool = False):
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"""
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Initialize the client registry.
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Args:
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allow_dynamic_registration: Whether to allow DCR for new clients
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"""
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self.allow_dynamic_registration = allow_dynamic_registration
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self._clients: Dict[str, MCPClientInfo] = {}
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self._load_static_clients()
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def _load_static_clients(self):
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"""Load statically configured clients from environment."""
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# Load from ALLOWED_MCP_CLIENTS environment variable
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allowed_clients = os.getenv("ALLOWED_MCP_CLIENTS", "").strip()
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if allowed_clients:
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# Parse comma-separated list
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for client_id in allowed_clients.split(","):
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client_id = client_id.strip()
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if client_id:
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# Create basic client info
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# In production, would load full metadata from database
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self._clients[client_id] = MCPClientInfo(
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client_id=client_id,
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name=self._get_client_name(client_id),
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redirect_uris=["http://localhost:*", "http://127.0.0.1:*"],
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allowed_scopes=["openid", "profile", "email", "mcp-server:api"],
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is_public=True,
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)
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logger.info(f"Registered static client: {client_id}")
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# Add well-known clients if not explicitly configured
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if not self._clients:
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self._add_well_known_clients()
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def _get_client_name(self, client_id: str) -> str:
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"""Get human-readable name for client_id."""
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known_names = {
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"claude-desktop": "Claude Desktop",
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"continue-dev": "Continue IDE Extension",
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"zed-editor": "Zed Editor",
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"vscode-mcp": "VS Code MCP Extension",
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"test-mcp-client": "Test MCP Client",
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}
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return known_names.get(client_id, client_id.replace("-", " ").title())
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def _add_well_known_clients(self):
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"""Add well-known MCP clients for testing and development."""
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well_known = [
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MCPClientInfo(
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client_id="claude-desktop",
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name="Claude Desktop",
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redirect_uris=["http://localhost:*", "http://127.0.0.1:*"],
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allowed_scopes=["openid", "profile", "email", "mcp-server:api"],
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is_public=True,
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metadata={"vendor": "Anthropic"},
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),
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MCPClientInfo(
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client_id="test-mcp-client",
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name="Test MCP Client",
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redirect_uris=["http://localhost:*", "http://127.0.0.1:*"],
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allowed_scopes=["openid", "profile", "email", "mcp-server:api"],
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is_public=True,
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metadata={"purpose": "testing"},
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),
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]
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for client in well_known:
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self._clients[client.client_id] = client
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logger.info(f"Registered well-known client: {client.client_id}")
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def validate_client(
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self,
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client_id: str,
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redirect_uri: Optional[str] = None,
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scopes: Optional[List[str]] = None,
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) -> tuple[bool, Optional[str]]:
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"""
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Validate a client_id and optionally its redirect_uri and scopes.
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Args:
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client_id: The client identifier to validate
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redirect_uri: Optional redirect URI to validate
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scopes: Optional list of scopes to validate
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Returns:
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Tuple of (is_valid, error_message)
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"""
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# Check if client exists
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client = self._clients.get(client_id)
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if not client:
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if self.allow_dynamic_registration:
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# In production, would attempt DCR here
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logger.info(f"Unknown client {client_id}, would attempt DCR")
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return True, None
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else:
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return False, f"Unknown client_id: {client_id}"
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# Validate redirect_uri if provided
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if redirect_uri:
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if not self._validate_redirect_uri(client, redirect_uri):
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return False, f"Invalid redirect_uri for client {client_id}"
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# Validate scopes if provided
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if scopes:
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invalid_scopes = set(scopes) - set(client.allowed_scopes)
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if invalid_scopes:
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return False, f"Invalid scopes for client {client_id}: {invalid_scopes}"
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return True, None
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def _validate_redirect_uri(self, client: MCPClientInfo, redirect_uri: str) -> bool:
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"""
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Validate redirect_uri against client's registered URIs.
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Args:
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client: The client info
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redirect_uri: The URI to validate
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Returns:
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True if valid, False otherwise
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"""
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# Parse the redirect URI
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from urllib.parse import urlparse
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parsed = urlparse(redirect_uri)
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# Check against registered patterns
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for pattern in client.redirect_uris:
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if "*" in pattern:
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# Handle wildcard port (localhost:*)
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pattern_base = pattern.replace(":*", "")
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if redirect_uri.startswith(pattern_base + ":"):
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# Validate it's localhost with a port
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if parsed.hostname in ["localhost", "127.0.0.1"]:
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return True
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elif redirect_uri == pattern:
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return True
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return False
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def register_client(self, client_info: MCPClientInfo) -> bool:
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"""
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Register a new MCP client (DCR support).
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Args:
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client_info: Client information to register
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Returns:
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True if registered successfully
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"""
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if not self.allow_dynamic_registration:
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logger.warning(f"DCR disabled, cannot register {client_info.client_id}")
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return False
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if client_info.client_id in self._clients:
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logger.warning(f"Client {client_info.client_id} already registered")
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return False
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self._clients[client_info.client_id] = client_info
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logger.info(f"Dynamically registered client: {client_info.client_id}")
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# In production, would persist to database
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return True
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def get_client(self, client_id: str) -> Optional[MCPClientInfo]:
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"""
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Get client information.
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Args:
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client_id: The client identifier
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Returns:
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Client info if found, None otherwise
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"""
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return self._clients.get(client_id)
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def list_clients(self) -> List[MCPClientInfo]:
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"""
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List all registered clients.
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Returns:
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List of client information
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"""
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return list(self._clients.values())
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# Global registry instance
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_registry: Optional[ClientRegistry] = None
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def get_client_registry() -> ClientRegistry:
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"""Get the global client registry instance."""
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global _registry
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if _registry is None:
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# Check if DCR is enabled
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allow_dcr = os.getenv("ENABLE_DCR", "false").lower() == "true"
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_registry = ClientRegistry(allow_dynamic_registration=allow_dcr)
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return _registry
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