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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Running the app
+
+```bash
+source .venv/bin/activate
+streamlit run app.py
+```
+
+Opens at `http://localhost:8501`. The `.venv/` virtual environment has all dependencies pre-installed.
+
+## Architecture
+
+Prism is a single-page Streamlit dashboard. `app.py` is the entry point — it owns the sidebar, injects global CSS, renders the market bar, and mounts the four tab components.
+
+**Data flow:** `app.py` → `components/` → `services/` → external APIs
+
+- `services/data_service.py` — all yfinance calls (price history, financials, market indices, ticker search). No API key required.
+- `services/fmp_service.py` — Financial Modeling Prep REST calls (ratios, peers, news). Requires `FMP_API_KEY` in `.env`.
+- `services/news_service.py` — Finnhub REST calls (company news, sentiment). Requires `FINNHUB_API_KEY` in `.env`.
+- `services/valuation_service.py` — pure Python DCF engine (Gordon Growth Model). Takes a FCF `pd.Series` + assumptions, returns a dict with per-year breakdown. No external calls.
+
+Every service function that hits a network is wrapped with `@st.cache_data(ttl=...)`. TTLs: financials 1h, news 10min, indices 5min, search 60s.
+
+**Components** (`components/`) are stateless render functions called `render_*(ticker)`. Each catches its own exceptions so one failing panel doesn't break the page.
+
+## Environment
+
+Copy `.env.example` → `.env` and fill in keys. Without keys, yfinance-backed features (price, financials, indices, search) still work; FMP and Finnhub features return empty gracefully.
+
+## Theme / styling
+
+`.streamlit/config.toml` sets the dark theme and `sans serif` font. Global metric/heading sizing is overridden via injected CSS at the top of `app.py` — adjust there if layout feels too large or small.