phase 2: symbol registry validation, seed data, nix dev shell

- Enhanced CompanyCreate with ticker format validation (1-10 uppercase letters)
- Enhanced SourceCreate with pydantic validators for source_type, access_policy, config URLs
- Added /health endpoint to symbol registry
- Seed data: 10 companies (AAPL, MSFT, NVDA, AMZN, GOOGL, JPM, JNJ, XOM, TSLA, META)
- Seed sources: Alpha Vantage (market), NewsAPI (news), SEC EDGAR (filings), Alpaca (paper trading)
- Seed watchlist: 'Starter 10' with all companies and aliases
- Added flake.nix dev shell (nixos-25.11) with Python 3.12, ruff, pytest, kubectl, helm
- 30 passing tests, lint clean, Docker build verified

services/symbol_registry/app.py

@@ -1,10 +1,12 @@
 """Symbol Registry API - FastAPI application."""
+import re
 from contextlib import asynccontextmanager
 from typing import List, Optional
+from urllib.parse import urlparse
 
 import asyncpg
 from fastapi import FastAPI, HTTPException
-from pydantic import BaseModel
+from pydantic import BaseModel, field_validator
 
 from services.shared.config import load_config
 from services.shared.db import get_pg_pool
@@ -24,6 +26,19 @@ async def lifespan(app: FastAPI):
 app = FastAPI(title="Stonks Oracle - Symbol Registry", lifespan=lifespan)
 
 
+@app.get("/health")
+async def health():
+    try:
+        await pool.fetchval("SELECT 1")
+        return {"status": "ok"}
+    except Exception:
+        raise HTTPException(503, "Database unavailable")
+
+TICKER_PATTERN = re.compile(r"^[A-Z]{1,10}$")
+VALID_SOURCE_TYPES = {"market_api", "news_api", "filings_api", "web_scrape", "broker"}
+VALID_ACCESS_POLICIES = {"internal", "public", "restricted"}
+
+
 # --- Request/Response Models ---
 
 class CompanyCreate(BaseModel):
@@ -34,6 +49,14 @@ class CompanyCreate(BaseModel):
     industry: Optional[str] = None
     market_cap_bucket: Optional[str] = None
 
+    @field_validator("ticker")
+    @classmethod
+    def validate_ticker(cls, v: str) -> str:
+        v = v.upper().strip()
+        if not TICKER_PATTERN.match(v):
+            raise ValueError(f"Ticker must be 1-10 uppercase letters, got: {v}")
+        return v
+
 
 class CompanyResponse(BaseModel):
     id: str
@@ -64,6 +87,31 @@ class SourceCreate(BaseModel):
     retention_days: int = 365
     access_policy: str = "internal"
 
+    @field_validator("source_type")
+    @classmethod
+    def validate_source_type(cls, v: str) -> str:
+        if v not in VALID_SOURCE_TYPES:
+            raise ValueError(f"source_type must be one of {VALID_SOURCE_TYPES}")
+        return v
+
+    @field_validator("access_policy")
+    @classmethod
+    def validate_access_policy(cls, v: str) -> str:
+        if v not in VALID_ACCESS_POLICIES:
+            raise ValueError(f"access_policy must be one of {VALID_ACCESS_POLICIES}")
+        return v
+
+    @field_validator("config")
+    @classmethod
+    def validate_config_urls(cls, v: dict) -> dict:
+        """Validate any URL fields in the config dict."""
+        for key in ("base_url", "endpoint", "url"):
+            if key in v and v[key]:
+                parsed = urlparse(str(v[key]))
+                if key == "base_url" and parsed.scheme not in ("http", "https"):
+                    raise ValueError(f"config.{key} must be a valid HTTP(S) URL")
+        return v
+
 
 VALID_SOURCE_TYPES = {"market_api", "news_api", "filings_api", "web_scrape", "broker"}
 
@@ -188,8 +236,10 @@ async def list_watchlist_members(watchlist_id: str):
 
 @app.post("/companies/{company_id}/sources", status_code=201)
 async def add_source(company_id: str, body: SourceCreate):
-    if body.source_type not in VALID_SOURCE_TYPES:
-        raise HTTPException(400, f"Invalid source_type. Must be one of: {VALID_SOURCE_TYPES}")
+    # Verify company exists
+    exists = await pool.fetchval("SELECT 1 FROM companies WHERE id = $1", company_id)
+    if not exists:
+        raise HTTPException(404, "Company not found")
     row = await pool.fetchrow(
         """INSERT INTO sources (company_id, source_type, source_name, config, credibility_score, retention_days, access_policy)
            VALUES ($1, $2, $3, $4, $5, $6, $7)