diff --git a/.kiro/specs/stonks-oracle/tasks.md b/.kiro/specs/stonks-oracle/tasks.md
index 2af1821..94fdd1e 100644
--- a/.kiro/specs/stonks-oracle/tasks.md
+++ b/.kiro/specs/stonks-oracle/tasks.md
@@ -17,11 +17,11 @@
 - [x] Stand up Superset with environment-backed datasource configuration
 
 ## Phase 2 - Symbol Registry and Source Management
-- [ ] Build symbol registry API endpoints for companies, aliases, watchlists, and sources
-- [ ] Add source credibility, retention policy, and access policy fields
-- [ ] Add source classes for market data API, news API, filings API, web scrape, and broker adapter
-- [ ] Add admin validation for duplicate tickers, invalid URLs, and unsupported source types
-- [ ] Add seed data support for an initial tracked watchlist
+- [x] Build symbol registry API endpoints for companies, aliases, watchlists, and sources
+- [x] Add source credibility, retention policy, and access policy fields
+- [x] Add source classes for market data API, news API, filings API, web scrape, and broker adapter
+- [x] Add admin validation for duplicate tickers, invalid URLs, and unsupported source types
+- [x] Add seed data support for an initial tracked watchlist
 ## Phase 3 
 - External API Adapters
 - [ ] Implement scheduler for symbol and source polling windows
diff --git a/flake.lock b/flake.lock
new file mode 100644
index 0000000..5a38e42
--- /dev/null
+++ b/flake.lock
@@ -0,0 +1,61 @@
+{
+  "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1775811116,
+        "narHash": "sha256-t+HZK42pB6N+i5RGbuy7Xluez/VvWbembBdvzsc23Ss=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "54170c54449ea4d6725efd30d719c5e505f1c10e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-25.11",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
diff --git a/flake.nix b/flake.nix
new file mode 100644
index 0000000..867b04f
--- /dev/null
+++ b/flake.nix
@@ -0,0 +1,70 @@
+{
+  description = "Stonks Oracle dev environment";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.11";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, flake-utils }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+        python = pkgs.python312;
+        pythonPkgs = python.pkgs;
+      in
+      {
+        devShells.default = pkgs.mkShell {
+          buildInputs = [
+            # Python + core deps
+            python
+            pythonPkgs.pip
+            pythonPkgs.virtualenv
+
+            # Native build deps for asyncpg, etc.
+            pkgs.postgresql_16.lib
+            pkgs.openssl
+            pkgs.pkg-config
+            pkgs.gcc
+
+            # Dev tools
+            pkgs.ruff
+            pkgs.kubectl
+            pkgs.kubernetes-helm
+            pkgs.docker-client
+
+            # Useful extras
+            pkgs.jq
+            pkgs.yq-go
+            pkgs.curl
+            pkgs.git
+          ];
+
+          shellHook = ''
+            # Create venv if it doesn't exist
+            if [ ! -d .venv ]; then
+              echo "Creating Python venv..."
+              python -m venv .venv
+            fi
+            source .venv/bin/activate
+
+            # Ensure nix-provided tools take precedence over venv
+            export PATH="${builtins.concatStringsSep ":" [
+              "${pkgs.ruff}/bin"
+              "${pkgs.kubectl}/bin"
+              "${pkgs.kubernetes-helm}/bin"
+            ]}:$PATH"
+
+            # Install deps if needed
+            if [ ! -f .venv/.installed ]; then
+              echo "Installing Python dependencies..."
+              pip install -q --exclude ruff -r requirements.txt 2>/dev/null || pip install -q -r requirements.txt
+              touch .venv/.installed
+            fi
+
+            export PYTHONPATH="$PWD:$PYTHONPATH"
+            echo "Stonks Oracle dev shell ready. Python $(python --version), ruff $(ruff --version)"
+          '';
+        };
+      });
+}
diff --git a/requirements.txt b/requirements.txt
index 165de7d..0f988d5 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -28,5 +28,5 @@ trino>=0.330.0
 pytest>=8.0.0
 pytest-asyncio>=0.24.0
 
-# Code quality
-ruff>=0.5.0
+# Code quality (provided by nix devshell, not pip)
+# ruff
diff --git a/services/symbol_registry/app.py b/services/symbol_registry/app.py
index 67bc5b6..292a4b6 100644
--- a/services/symbol_registry/app.py
+++ b/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)
diff --git a/services/symbol_registry/seed.py b/services/symbol_registry/seed.py
new file mode 100644
index 0000000..e5044e9
--- /dev/null
+++ b/services/symbol_registry/seed.py
@@ -0,0 +1,184 @@
+"""Seed data for initial tracked watchlist.
+
+Run against a live database to populate the starter companies, aliases,
+watchlist, and source configurations.
+
+Usage:
+    python -m services.symbol_registry.seed
+"""
+import asyncio
+import logging
+
+import asyncpg
+
+from services.shared.config import load_config
+from services.shared.db import get_pg_pool
+
+logging.basicConfig(level=logging.INFO)
+logger = logging.getLogger("seed")
+
+# --- Seed Companies ---
+# Diverse mix: mega-cap tech, finance, healthcare, energy, consumer
+COMPANIES = [
+    {"ticker": "AAPL", "legal_name": "Apple Inc.", "exchange": "NASDAQ", "sector": "Technology", "industry": "Consumer Electronics", "market_cap_bucket": "mega"},
+    {"ticker": "MSFT", "legal_name": "Microsoft Corporation", "exchange": "NASDAQ", "sector": "Technology", "industry": "Software", "market_cap_bucket": "mega"},
+    {"ticker": "NVDA", "legal_name": "NVIDIA Corporation", "exchange": "NASDAQ", "sector": "Technology", "industry": "Semiconductors", "market_cap_bucket": "mega"},
+    {"ticker": "AMZN", "legal_name": "Amazon.com Inc.", "exchange": "NASDAQ", "sector": "Consumer Cyclical", "industry": "Internet Retail", "market_cap_bucket": "mega"},
+    {"ticker": "GOOGL", "legal_name": "Alphabet Inc.", "exchange": "NASDAQ", "sector": "Technology", "industry": "Internet Content", "market_cap_bucket": "mega"},
+    {"ticker": "JPM", "legal_name": "JPMorgan Chase & Co.", "exchange": "NYSE", "sector": "Financial Services", "industry": "Banks", "market_cap_bucket": "mega"},
+    {"ticker": "JNJ", "legal_name": "Johnson & Johnson", "exchange": "NYSE", "sector": "Healthcare", "industry": "Drug Manufacturers", "market_cap_bucket": "mega"},
+    {"ticker": "XOM", "legal_name": "Exxon Mobil Corporation", "exchange": "NYSE", "sector": "Energy", "industry": "Oil & Gas Integrated", "market_cap_bucket": "mega"},
+    {"ticker": "TSLA", "legal_name": "Tesla Inc.", "exchange": "NASDAQ", "sector": "Consumer Cyclical", "industry": "Auto Manufacturers", "market_cap_bucket": "large"},
+    {"ticker": "META", "legal_name": "Meta Platforms Inc.", "exchange": "NASDAQ", "sector": "Technology", "industry": "Internet Content", "market_cap_bucket": "mega"},
+]
+
+# --- Aliases ---
+ALIASES = {
+    "AAPL": [("Apple", "brand"), ("iPhone", "product")],
+    "MSFT": [("Microsoft", "brand"), ("Azure", "product"), ("Windows", "product")],
+    "NVDA": [("NVIDIA", "brand"), ("GeForce", "product"), ("CUDA", "product")],
+    "AMZN": [("Amazon", "brand"), ("AWS", "product"), ("Prime", "product")],
+    "GOOGL": [("Google", "brand"), ("Alphabet", "legal_name"), ("YouTube", "product")],
+    "JPM": [("JPMorgan", "brand"), ("Chase", "brand")],
+    "JNJ": [("J&J", "brand")],
+    "XOM": [("Exxon", "brand"), ("ExxonMobil", "brand")],
+    "TSLA": [("Tesla", "brand")],
+    "META": [("Facebook", "brand"), ("Instagram", "product"), ("WhatsApp", "product")],
+}
+
+# --- Source configs per company ---
+# Alpha Vantage for market data (free: 25 req/day)
+# NewsAPI for news (free: 100 req/day)
+# SEC EDGAR for filings (free, rate-limited by user-agent)
+# Alpaca for paper trading (free unlimited paper)
+
+SOURCES_PER_COMPANY = [
+    {
+        "source_type": "market_api",
+        "source_name": "Alpha Vantage",
+        "credibility_score": 0.9,
+        "config": {
+            "provider": "alpha_vantage",
+            "base_url": "https://www.alphavantage.co",
+            "endpoint": "/query",
+            "functions": ["TIME_SERIES_DAILY", "GLOBAL_QUOTE", "OVERVIEW"],
+        },
+    },
+    {
+        "source_type": "news_api",
+        "source_name": "NewsAPI",
+        "credibility_score": 0.7,
+        "config": {
+            "provider": "newsapi",
+            "base_url": "https://newsapi.org",
+            "endpoint": "/v2/everything",
+            "page_size": 20,
+        },
+    },
+    {
+        "source_type": "filings_api",
+        "source_name": "SEC EDGAR",
+        "credibility_score": 1.0,
+        "config": {
+            "provider": "sec_edgar",
+            "base_url": "https://efts.sec.gov",
+            "forms": ["8-K", "10-Q", "10-K"],
+            "user_agent": "StonksOracle/1.0",
+        },
+    },
+]
+
+# Broker source — one per account, not per company
+BROKER_SOURCE = {
+    "source_type": "broker",
+    "source_name": "Alpaca Paper",
+    "credibility_score": 1.0,
+    "config": {
+        "provider": "alpaca",
+        "base_url": "https://paper-api.alpaca.markets",
+        "mode": "paper",
+    },
+}
+
+
+async def seed(pool: asyncpg.Pool) -> None:
+    """Insert seed data. Skips existing records."""
+    company_ids = {}
+
+    # Companies
+    for c in COMPANIES:
+        row = await pool.fetchrow(
+            """INSERT INTO companies (ticker, legal_name, exchange, sector, industry, market_cap_bucket)
+               VALUES ($1, $2, $3, $4, $5, $6)
+               ON CONFLICT (ticker, exchange) DO UPDATE SET legal_name = EXCLUDED.legal_name
+               RETURNING id, ticker""",
+            c["ticker"], c["legal_name"], c["exchange"],
+            c["sector"], c["industry"], c["market_cap_bucket"],
+        )
+        company_ids[row["ticker"]] = row["id"]
+        logger.info(f"Company: {row['ticker']} -> {row['id']}")
+
+    # Aliases
+    for ticker, aliases in ALIASES.items():
+        cid = company_ids.get(ticker)
+        if not cid:
+            continue
+        for alias, alias_type in aliases:
+            await pool.execute(
+                """INSERT INTO company_aliases (company_id, alias, alias_type)
+                   VALUES ($1, $2, $3) ON CONFLICT DO NOTHING""",
+                cid, alias, alias_type,
+            )
+    logger.info("Aliases seeded")
+
+    # Watchlist
+    wl = await pool.fetchrow(
+        """INSERT INTO watchlists (name, description)
+           VALUES ('Starter 10', 'Initial tracked watchlist — 10 diverse mega/large-cap symbols')
+           ON CONFLICT (name) DO UPDATE SET description = EXCLUDED.description
+           RETURNING id""",
+    )
+    wl_id = wl["id"]
+    for cid in company_ids.values():
+        await pool.execute(
+            "INSERT INTO watchlist_members (watchlist_id, company_id) VALUES ($1, $2) ON CONFLICT DO NOTHING",
+            wl_id, cid,
+        )
+    logger.info(f"Watchlist 'Starter 10' -> {wl_id}")
+
+    # Sources per company
+    for ticker, cid in company_ids.items():
+        for src in SOURCES_PER_COMPANY:
+            await pool.execute(
+                """INSERT INTO sources (company_id, source_type, source_name, config, credibility_score)
+                   VALUES ($1, $2, $3, $4, $5)
+                   ON CONFLICT DO NOTHING""",
+                cid, src["source_type"], src["source_name"],
+                src["config"], src["credibility_score"],
+            )
+        # Broker source only for the first company (account-level)
+        if ticker == COMPANIES[0]["ticker"]:
+            await pool.execute(
+                """INSERT INTO sources (company_id, source_type, source_name, config, credibility_score)
+                   VALUES ($1, $2, $3, $4, $5)
+                   ON CONFLICT DO NOTHING""",
+                cid, BROKER_SOURCE["source_type"], BROKER_SOURCE["source_name"],
+                BROKER_SOURCE["config"], BROKER_SOURCE["credibility_score"],
+            )
+    logger.info("Sources seeded")
+
+    total = await pool.fetchval("SELECT count(*) FROM companies")
+    logger.info(f"Seed complete: {total} companies, watchlist with {len(company_ids)} members")
+
+
+async def main() -> None:
+    config = load_config()
+    pool = await get_pg_pool(config)
+    try:
+        await seed(pool)
+    finally:
+        await pool.close()
+
+
+if __name__ == "__main__":
+    asyncio.run(main())
diff --git a/tests/test_symbol_registry.py b/tests/test_symbol_registry.py
new file mode 100644
index 0000000..c940700
--- /dev/null
+++ b/tests/test_symbol_registry.py
@@ -0,0 +1,105 @@
+"""Tests for symbol registry validation and seed data."""
+import pytest
+from pydantic import ValidationError
+
+# Import after path setup
+from services.symbol_registry.app import CompanyCreate, SourceCreate, VALID_SOURCE_TYPES
+from services.symbol_registry.seed import COMPANIES, ALIASES, SOURCES_PER_COMPANY
+
+
+# --- CompanyCreate validation ---
+
+def test_ticker_uppercased():
+    c = CompanyCreate(ticker="aapl", legal_name="Apple Inc.")
+    assert c.ticker == "AAPL"
+
+
+def test_ticker_strips_whitespace():
+    c = CompanyCreate(ticker="  MSFT  ", legal_name="Microsoft")
+    assert c.ticker == "MSFT"
+
+
+def test_ticker_rejects_numbers():
+    with pytest.raises(ValidationError):
+        CompanyCreate(ticker="123", legal_name="Bad")
+
+
+def test_ticker_rejects_empty():
+    with pytest.raises(ValidationError):
+        CompanyCreate(ticker="", legal_name="Bad")
+
+
+def test_ticker_rejects_too_long():
+    with pytest.raises(ValidationError):
+        CompanyCreate(ticker="ABCDEFGHIJK", legal_name="Bad")
+
+
+def test_ticker_rejects_special_chars():
+    with pytest.raises(ValidationError):
+        CompanyCreate(ticker="AA-PL", legal_name="Bad")
+
+
+# --- SourceCreate validation ---
+
+def test_source_valid_types():
+    for st in VALID_SOURCE_TYPES:
+        s = SourceCreate(source_type=st, source_name="test")
+        assert s.source_type == st
+
+
+def test_source_rejects_invalid_type():
+    with pytest.raises(ValidationError):
+        SourceCreate(source_type="invalid_type", source_name="test")
+
+
+def test_source_rejects_invalid_access_policy():
+    with pytest.raises(ValidationError):
+        SourceCreate(source_type="market_api", source_name="test", access_policy="secret")
+
+
+def test_source_validates_config_url():
+    s = SourceCreate(
+        source_type="market_api",
+        source_name="test",
+        config={"base_url": "https://api.example.com"},
+    )
+    assert s.config["base_url"] == "https://api.example.com"
+
+
+def test_source_rejects_bad_config_url():
+    with pytest.raises(ValidationError):
+        SourceCreate(
+            source_type="market_api",
+            source_name="test",
+            config={"base_url": "not-a-url"},
+        )
+
+
+# --- Seed data integrity ---
+
+def test_seed_companies_have_required_fields():
+    for c in COMPANIES:
+        assert c["ticker"]
+        assert c["legal_name"]
+        assert c["exchange"]
+        assert c["sector"]
+
+
+def test_seed_companies_unique_tickers():
+    tickers = [c["ticker"] for c in COMPANIES]
+    assert len(tickers) == len(set(tickers))
+
+
+def test_seed_aliases_reference_valid_tickers():
+    tickers = {c["ticker"] for c in COMPANIES}
+    for ticker in ALIASES:
+        assert ticker in tickers, f"Alias references unknown ticker: {ticker}"
+
+
+def test_seed_sources_have_valid_types():
+    for src in SOURCES_PER_COMPANY:
+        assert src["source_type"] in VALID_SOURCE_TYPES
+
+
+def test_seed_has_ten_companies():
+    assert len(COMPANIES) == 10