feat: brain service — self-contained second brain knowledge manager

Full backend service with:
- FastAPI REST API with CRUD, search, reprocess endpoints
- PostgreSQL + pgvector for items and semantic search
- Redis + RQ for background job processing
- Meilisearch for fast keyword/filter search
- Browserless/Chrome for JS rendering and screenshots
- OpenAI structured output for AI classification
- Local file storage with S3-ready abstraction
- Gateway auth via X-Gateway-User-Id header
- Own docker-compose stack (6 containers)

Classification: fixed folders (Home/Family/Work/Travel/Knowledge/Faith/Projects)
and fixed tags (28 predefined). AI assigns exactly 1 folder, 2-3 tags, title,
summary, and confidence score per item.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

gateway/config.py

@@ -59,6 +59,9 @@ OPENAI_MODEL = os.environ.get("OPENAI_MODEL", "gpt-5.2")
 
 # ── Session config ──
 SESSION_MAX_AGE = int(os.environ.get("SESSION_MAX_AGE", 30 * 86400))  # 30 days
+DEV_AUTO_LOGIN = os.environ.get("DEV_AUTO_LOGIN", "").lower() in {"1", "true", "yes", "on"}
+DEV_AUTO_LOGIN_USERNAME = os.environ.get("DEV_AUTO_LOGIN_USERNAME", "dev")
+DEV_AUTO_LOGIN_DISPLAY_NAME = os.environ.get("DEV_AUTO_LOGIN_DISPLAY_NAME", "Dev User")
 
 # ── Ensure data dir exists ──
 DATA_DIR.mkdir(parents=True, exist_ok=True)
@@ -66,4 +69,3 @@ DATA_DIR.mkdir(parents=True, exist_ok=True)
 # Note: All internal services use plain HTTP (Docker network).
 # No custom SSL context needed. External calls (OpenAI, SMTP2GO, Open Library)
 # use default TLS verification.
-

gateway/responses.py

@@ -5,8 +5,8 @@ Platform Gateway — Response helpers mixed into GatewayHandler.
 import json
 from http.cookies import SimpleCookie
 
-from config import SESSION_MAX_AGE
-from sessions import get_session_user
+from config import SESSION_MAX_AGE, DEV_AUTO_LOGIN
+from sessions import get_session_user, get_or_create_dev_user
 
 
 class ResponseMixin:
@@ -30,6 +30,8 @@ class ResponseMixin:
         return None
 
     def _get_user(self):
+        if DEV_AUTO_LOGIN and self.headers.get("X-Dev-Auto-Login") == "1":
+            return get_or_create_dev_user()
         token = self._get_session_token()
         return get_session_user(token)
 

gateway/sessions.py

@@ -4,8 +4,9 @@ Platform Gateway — Session and service-connection helpers.
 
 import secrets
 from datetime import datetime, timedelta
+import bcrypt
 
-from config import SESSION_MAX_AGE
+from config import SESSION_MAX_AGE, DEV_AUTO_LOGIN_USERNAME, DEV_AUTO_LOGIN_DISPLAY_NAME
 from database import get_db
 
 
@@ -52,6 +53,24 @@ def get_service_token(user_id, service):
     return dict(row) if row else None
 
 
+def get_or_create_dev_user():
+    conn = get_db()
+    row = conn.execute("SELECT * FROM users WHERE username = ?", (DEV_AUTO_LOGIN_USERNAME,)).fetchone()
+    if row:
+        conn.close()
+        return dict(row)
+
+    pw_hash = bcrypt.hashpw(secrets.token_hex(16).encode(), bcrypt.gensalt()).decode()
+    conn.execute(
+        "INSERT INTO users (username, password_hash, display_name) VALUES (?, ?, ?)",
+        (DEV_AUTO_LOGIN_USERNAME, pw_hash, DEV_AUTO_LOGIN_DISPLAY_NAME)
+    )
+    conn.commit()
+    row = conn.execute("SELECT * FROM users WHERE username = ?", (DEV_AUTO_LOGIN_USERNAME,)).fetchone()
+    conn.close()
+    return dict(row) if row else None
+
+
 def set_service_token(user_id, service, auth_token, auth_type="bearer"):
     conn = get_db()
     conn.execute("""