feat(mcp): add Connectors — URL+headers and OAuth 2.1

backend/.env.example

@@ -1,5 +1,8 @@
 PORT=3001
 FRONTEND_URL=http://localhost:3000
+# Externally-reachable backend URL. Used to build the OAuth callback URL for
+# MCP connectors. Defaults to http://localhost:${PORT} when unset.
+BACKEND_PUBLIC_URL=http://localhost:3001
 SUPABASE_URL=https://your-project.supabase.co
 SUPABASE_SECRET_KEY=your-supabase-service-role-key
 

backend/migrations/000_one_shot_schema.sql

@@ -272,6 +272,56 @@ begin
 end;
 $$;
 
+-- ---------------------------------------------------------------------------
+-- User MCP servers
+-- ---------------------------------------------------------------------------
+
+create table if not exists public.user_mcp_servers (
+  id uuid primary key default gen_random_uuid(),
+  user_id uuid not null references auth.users(id) on delete cascade,
+  slug text not null,
+  name text not null,
+  url text not null,
+  headers jsonb not null default '{}'::jsonb,
+  enabled boolean not null default true,
+  last_error text,
+  auth_type text not null default 'headers'
+    check (auth_type in ('headers', 'oauth')),
+  oauth_metadata jsonb,
+  oauth_tokens jsonb,
+  oauth_code_verifier text,
+  created_at timestamptz not null default now(),
+  updated_at timestamptz not null default now(),
+  constraint user_mcp_servers_slug_format
+    check (slug ~ '^[a-z0-9_-]{1,24}$'),
+  unique (user_id, slug)
+);
+
+create index if not exists idx_user_mcp_servers_user
+  on public.user_mcp_servers(user_id, enabled);
+
+alter table public.user_mcp_servers enable row level security;
+
+drop policy if exists "Users can view their own MCP servers" on public.user_mcp_servers;
+create policy "Users can view their own MCP servers"
+  on public.user_mcp_servers for select
+  using (auth.uid() = user_id);
+
+drop policy if exists "Users can insert their own MCP servers" on public.user_mcp_servers;
+create policy "Users can insert their own MCP servers"
+  on public.user_mcp_servers for insert
+  with check (auth.uid() = user_id);
+
+drop policy if exists "Users can update their own MCP servers" on public.user_mcp_servers;
+create policy "Users can update their own MCP servers"
+  on public.user_mcp_servers for update
+  using (auth.uid() = user_id);
+
+drop policy if exists "Users can delete their own MCP servers" on public.user_mcp_servers;
+create policy "Users can delete their own MCP servers"
+  on public.user_mcp_servers for delete
+  using (auth.uid() = user_id);
+
 -- ---------------------------------------------------------------------------
 -- Tabular reviews
 -- ---------------------------------------------------------------------------

backend/migrations/001_user_mcp_servers.sql

@@ -0,0 +1,49 @@
+-- User-configurable MCP (Model Context Protocol) servers.
+-- Each row points the chat backend at a Streamable-HTTP MCP endpoint that
+-- exposes additional tools. Tools discovered from these endpoints are merged
+-- into the per-request tool list and routed under the `mcp__<slug>__` prefix.
+--
+-- Sensitive header values (e.g. Authorization tokens) live in the `headers`
+-- jsonb column. Access is gated by Postgres RLS — owner-only — matching the
+-- precedent set by user_profiles.claude_api_key / gemini_api_key.
+
+create table if not exists public.user_mcp_servers (
+  id uuid primary key default gen_random_uuid(),
+  user_id uuid not null references auth.users(id) on delete cascade,
+  slug text not null,
+  name text not null,
+  url text not null,
+  headers jsonb not null default '{}'::jsonb,
+  enabled boolean not null default true,
+  last_error text,
+  created_at timestamptz not null default now(),
+  updated_at timestamptz not null default now(),
+  constraint user_mcp_servers_slug_format
+    check (slug ~ '^[a-z0-9_-]{1,24}$'),
+  unique (user_id, slug)
+);
+
+create index if not exists idx_user_mcp_servers_user
+  on public.user_mcp_servers(user_id, enabled);
+
+alter table public.user_mcp_servers enable row level security;
+
+drop policy if exists "Users can view their own MCP servers" on public.user_mcp_servers;
+create policy "Users can view their own MCP servers"
+  on public.user_mcp_servers for select
+  using (auth.uid() = user_id);
+
+drop policy if exists "Users can insert their own MCP servers" on public.user_mcp_servers;
+create policy "Users can insert their own MCP servers"
+  on public.user_mcp_servers for insert
+  with check (auth.uid() = user_id);
+
+drop policy if exists "Users can update their own MCP servers" on public.user_mcp_servers;
+create policy "Users can update their own MCP servers"
+  on public.user_mcp_servers for update
+  using (auth.uid() = user_id);
+
+drop policy if exists "Users can delete their own MCP servers" on public.user_mcp_servers;
+create policy "Users can delete their own MCP servers"
+  on public.user_mcp_servers for delete
+  using (auth.uid() = user_id);

backend/migrations/002_user_mcp_servers_oauth.sql

@@ -0,0 +1,16 @@
+-- OAuth 2.1 support for user-configured MCP connectors.
+-- Adds auth-mode toggle + storage for the discovered authorization-server
+-- metadata, the dynamically-registered client info, the access/refresh
+-- tokens, and the (transient) PKCE verifier between /oauth/start and
+-- /oauth/callback.
+--
+-- Tokens are stored at-rest in jsonb (RLS owner-only). Per-row encryption
+-- is intentionally deferred to a separate hardening PR — this matches the
+-- existing precedent for user_profiles.{claude,gemini}_api_key.
+
+alter table public.user_mcp_servers
+  add column if not exists auth_type text not null default 'headers'
+    check (auth_type in ('headers', 'oauth')),
+  add column if not exists oauth_metadata jsonb,
+  add column if not exists oauth_tokens jsonb,
+  add column if not exists oauth_code_verifier text;