refactor: split into idx-core library and idx-cli binary workspace

Phase 2 of docs/DESIGN.md, no behavior change:

- crates/idx-core (library): api, analysis, cache, config file handling
  and provider selection, curl_impersonate, error, ownership, runtime,
  plus the shared test fixtures. clap derives are behind an optional
  `clap` feature so the library does not require clap.
- crates/idx-cli (binary `idx`): cli/, output/, and IdxConfig (output
  format and color resolution). Package and binary names are unchanged.
- config.rs is split: file read/write and validation move to core; a
  CLI test keeps core's OUTPUT_VALUES in sync with OutputSetting.
- ownership::db::open_db/db_path drop their unused IdxConfig argument.
- One workspace version; shared dependency versions; no third-party
  version changes in Cargo.lock. LICENSE is symlinked into each crate.
- flake: workspace version, new source paths, and a per-crate package
  check (idx-cli is built from its tarball against packaged idx-core,
  since idx-core is not on crates.io yet). CI cache key, release path
  filter, and the golden whitespace-hook exclusion follow the new layout.

Parity: all 143 golden outputs match byte for byte without
regeneration; 157 core + 17 CLI unit tests (173 before plus the new
OUTPUT_VALUES sync test), 62 CLI tests pass. Live A/B against main:
16/16 stocks cases identical; ownership discover got IDX 403 on both
(exit 4 vs 1 is the phase 1 exit-code change).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/idx-core/src/analysis/fundamental.rs

@@ -0,0 +1,468 @@
+use serde::{Deserialize, Serialize};
+
+use crate::api::types::Fundamentals;
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct GrowthReport {
+    pub revenue_growth: Option<f64>,
+    pub earnings_growth: Option<f64>,
+    pub revenue_growth_pct: Option<f64>,
+    pub earnings_growth_pct: Option<f64>,
+    pub revenue_signal: String,
+    pub earnings_signal: String,
+    pub overall_signal: String,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ValuationReport {
+    pub pe_trailing: Option<f64>,
+    pub pe_forward: Option<f64>,
+    pub pb: Option<f64>,
+    pub roe: Option<f64>,
+    pub roe_pct: Option<f64>,
+    pub net_margin: Option<f64>,
+    pub net_margin_pct: Option<f64>,
+    pub ev_ebitda: Option<f64>,
+    pub pe_signal: String,
+    pub pb_signal: String,
+    pub roe_signal: String,
+    pub margin_signal: String,
+    pub ev_ebitda_signal: String,
+    pub overall_signal: String,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct RiskReport {
+    pub debt_to_equity: Option<f64>,
+    pub current_ratio: Option<f64>,
+    pub roa: Option<f64>,
+    pub roa_pct: Option<f64>,
+    pub de_signal: String,
+    pub current_ratio_signal: String,
+    pub overall_signal: String,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct FundamentalReport {
+    pub symbol: String,
+    pub growth: GrowthReport,
+    pub valuation: ValuationReport,
+    pub risk: RiskReport,
+    pub overall_signal: String,
+}
+
+pub fn analyze_growth(fundamentals: &Fundamentals) -> GrowthReport {
+    let revenue_signal = growth_signal(fundamentals.revenue_growth);
+    let earnings_signal = growth_signal(fundamentals.earnings_growth);
+    let positive = ["strong", "moderate"];
+    let negative = ["declining", "contracting"];
+
+    let overall_signal = if revenue_signal == "no data" && earnings_signal == "no data" {
+        "no data"
+    } else if positive.contains(&revenue_signal) && positive.contains(&earnings_signal) {
+        "growing"
+    } else if negative.contains(&revenue_signal) && negative.contains(&earnings_signal) {
+        "shrinking"
+    } else if revenue_signal == "no data" || earnings_signal == "no data" {
+        let other = if earnings_signal == "no data" {
+            revenue_signal
+        } else {
+            earnings_signal
+        };
+        if negative.contains(&other) {
+            "mixed"
+        } else {
+            "incomplete data"
+        }
+    } else {
+        "mixed"
+    };
+
+    GrowthReport {
+        revenue_growth: fundamentals.revenue_growth,
+        earnings_growth: fundamentals.earnings_growth,
+        revenue_growth_pct: ratio_pct(fundamentals.revenue_growth),
+        earnings_growth_pct: ratio_pct(fundamentals.earnings_growth),
+        revenue_signal: revenue_signal.to_string(),
+        earnings_signal: earnings_signal.to_string(),
+        overall_signal: overall_signal.to_string(),
+    }
+}
+
+pub fn analyze_valuation(fundamentals: &Fundamentals) -> ValuationReport {
+    let ev_ebitda = match (fundamentals.enterprise_value, fundamentals.ebitda) {
+        (Some(ev), Some(ebitda)) if ebitda > 0 => Some(round2(ev as f64 / ebitda as f64)),
+        _ => None,
+    };
+
+    let pe_signal = pe_signal(fundamentals.trailing_pe);
+    let pb_signal = pb_signal(fundamentals.price_to_book);
+    let ev_ebitda_signal = ev_ebitda_signal(ev_ebitda);
+    let cheap = ["deep value", "undervalued"];
+    let rich = ["premium", "expensive"];
+    let price_signals: Vec<&str> = [pe_signal, pb_signal, ev_ebitda_signal]
+        .into_iter()
+        .filter(|signal| *signal != "no data")
+        .collect();
+
+    let overall_signal = if price_signals.is_empty() {
+        "no data"
+    } else {
+        let cheap_count = price_signals
+            .iter()
+            .filter(|signal| cheap.contains(signal))
+            .count();
+        let rich_count = price_signals
+            .iter()
+            .filter(|signal| rich.contains(signal))
+            .count();
+
+        if cheap_count > price_signals.len() / 2 {
+            "undervalued"
+        } else if rich_count > price_signals.len() / 2 {
+            "expensive"
+        } else {
+            "fairly valued"
+        }
+    };
+
+    ValuationReport {
+        pe_trailing: fundamentals.trailing_pe,
+        pe_forward: fundamentals.forward_pe,
+        pb: fundamentals.price_to_book,
+        roe: fundamentals.return_on_equity,
+        roe_pct: ratio_pct(fundamentals.return_on_equity),
+        net_margin: fundamentals.profit_margins,
+        net_margin_pct: ratio_pct(fundamentals.profit_margins),
+        ev_ebitda,
+        pe_signal: pe_signal.to_string(),
+        pb_signal: pb_signal.to_string(),
+        roe_signal: roe_signal(fundamentals.return_on_equity).to_string(),
+        margin_signal: margin_signal(fundamentals.profit_margins).to_string(),
+        ev_ebitda_signal: ev_ebitda_signal.to_string(),
+        overall_signal: overall_signal.to_string(),
+    }
+}
+
+pub fn analyze_risk(fundamentals: &Fundamentals) -> RiskReport {
+    let de_signal = de_signal(fundamentals.debt_to_equity);
+    let current_ratio_signal = cr_signal(fundamentals.current_ratio);
+
+    let overall_signal = if de_signal == "no data" && current_ratio_signal == "no data" {
+        "no data"
+    } else if de_signal == "no data" || current_ratio_signal == "no data" {
+        "incomplete data"
+    } else if de_signal == "highly leveraged" || current_ratio_signal == "weak" {
+        "high risk"
+    } else if de_signal == "conservative" && matches!(current_ratio_signal, "strong" | "adequate") {
+        "low risk"
+    } else {
+        "moderate risk"
+    };
+
+    RiskReport {
+        debt_to_equity: fundamentals.debt_to_equity,
+        current_ratio: fundamentals.current_ratio,
+        roa: fundamentals.return_on_assets,
+        roa_pct: ratio_pct(fundamentals.return_on_assets),
+        de_signal: de_signal.to_string(),
+        current_ratio_signal: current_ratio_signal.to_string(),
+        overall_signal: overall_signal.to_string(),
+    }
+}
+
+pub fn analyze_fundamental(symbol: &str, fundamentals: &Fundamentals) -> FundamentalReport {
+    let growth = analyze_growth(fundamentals);
+    let valuation = analyze_valuation(fundamentals);
+    let risk = analyze_risk(fundamentals);
+
+    let overall_signal = if growth.overall_signal == "growing"
+        && valuation.overall_signal != "expensive"
+        && risk.overall_signal != "high risk"
+    {
+        "healthy"
+    } else if growth.overall_signal == "shrinking" && risk.overall_signal == "high risk" {
+        "weak"
+    } else if [
+        &growth.overall_signal,
+        &valuation.overall_signal,
+        &risk.overall_signal,
+    ]
+    .into_iter()
+    .all(|signal| *signal == "no data")
+    {
+        "no data"
+    } else {
+        "mixed"
+    };
+
+    FundamentalReport {
+        symbol: symbol.to_string(),
+        growth,
+        valuation,
+        risk,
+        overall_signal: overall_signal.to_string(),
+    }
+}
+
+fn growth_signal(value: Option<f64>) -> &'static str {
+    let Some(value) = value else {
+        return "no data";
+    };
+    if value >= 0.20 {
+        "strong"
+    } else if value >= 0.10 {
+        "moderate"
+    } else if value >= 0.0 {
+        "slow"
+    } else if value >= -0.10 {
+        "declining"
+    } else {
+        "contracting"
+    }
+}
+
+fn pe_signal(value: Option<f64>) -> &'static str {
+    let Some(value) = value else {
+        return "no data";
+    };
+    if value <= 0.0 {
+        "no data"
+    } else if value < 8.0 {
+        "deep value"
+    } else if value < 15.0 {
+        "undervalued"
+    } else if value < 25.0 {
+        "fairly valued"
+    } else if value < 40.0 {
+        "premium"
+    } else {
+        "expensive"
+    }
+}
+
+fn pb_signal(value: Option<f64>) -> &'static str {
+    let Some(value) = value else {
+        return "no data";
+    };
+    if value <= 0.0 {
+        "no data"
+    } else if value < 1.0 {
+        "deep value"
+    } else if value < 2.0 {
+        "undervalued"
+    } else if value < 4.0 {
+        "fairly valued"
+    } else {
+        "expensive"
+    }
+}
+
+fn roe_signal(value: Option<f64>) -> &'static str {
+    let Some(value) = value else {
+        return "no data";
+    };
+    if value >= 0.20 {
+        "excellent"
+    } else if value >= 0.15 {
+        "strong"
+    } else if value >= 0.10 {
+        "adequate"
+    } else if value >= 0.0 {
+        "weak"
+    } else {
+        "negative"
+    }
+}
+
+fn margin_signal(value: Option<f64>) -> &'static str {
+    let Some(value) = value else {
+        return "no data";
+    };
+    if value >= 0.20 {
+        "excellent"
+    } else if value >= 0.10 {
+        "healthy"
+    } else if value >= 0.05 {
+        "adequate"
+    } else if value >= 0.0 {
+        "thin"
+    } else {
+        "negative"
+    }
+}
+
+fn ev_ebitda_signal(value: Option<f64>) -> &'static str {
+    let Some(value) = value else {
+        return "no data";
+    };
+    if value <= 0.0 {
+        "no data"
+    } else if value < 8.0 {
+        "undervalued"
+    } else if value < 14.0 {
+        "fairly valued"
+    } else if value < 20.0 {
+        "premium"
+    } else {
+        "expensive"
+    }
+}
+
+fn de_signal(value: Option<f64>) -> &'static str {
+    let Some(value) = value else {
+        return "no data";
+    };
+    if value < 0.0 {
+        "negative equity"
+    } else if value < 50.0 {
+        "conservative"
+    } else if value < 100.0 {
+        "moderate"
+    } else if value < 200.0 {
+        "leveraged"
+    } else {
+        "highly leveraged"
+    }
+}
+
+fn cr_signal(value: Option<f64>) -> &'static str {
+    let Some(value) = value else {
+        return "no data";
+    };
+    if value >= 2.0 {
+        "strong"
+    } else if value >= 1.5 {
+        "adequate"
+    } else if value >= 1.0 {
+        "tight"
+    } else {
+        "weak"
+    }
+}
+
+fn ratio_pct(value: Option<f64>) -> Option<f64> {
+    value.map(|value| round2(value * 100.0))
+}
+
+fn round2(value: f64) -> f64 {
+    (value * 100.0).round() / 100.0
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{
+        Fundamentals, analyze_fundamental, analyze_growth, analyze_risk, analyze_valuation,
+        cr_signal, de_signal, ev_ebitda_signal, growth_signal, margin_signal, pb_signal, pe_signal,
+        roe_signal,
+    };
+
+    fn sample_fundamentals() -> Fundamentals {
+        Fundamentals {
+            trailing_pe: Some(12.5),
+            forward_pe: Some(11.0),
+            price_to_book: Some(1.8),
+            return_on_equity: Some(0.18),
+            profit_margins: Some(0.12),
+            return_on_assets: Some(0.06),
+            revenue_growth: Some(0.12),
+            earnings_growth: Some(0.22),
+            debt_to_equity: Some(40.0),
+            current_ratio: Some(1.6),
+            enterprise_value: Some(120),
+            ebitda: Some(15),
+            market_cap: Some(100),
+        }
+    }
+
+    #[test]
+    fn growth_signal_thresholds_match_python() {
+        assert_eq!(growth_signal(None), "no data");
+        assert_eq!(growth_signal(Some(0.20)), "strong");
+        assert_eq!(growth_signal(Some(0.10)), "moderate");
+        assert_eq!(growth_signal(Some(0.0)), "slow");
+        assert_eq!(growth_signal(Some(-0.10)), "declining");
+        assert_eq!(growth_signal(Some(-0.11)), "contracting");
+    }
+
+    #[test]
+    fn valuation_signal_thresholds_match_python() {
+        assert_eq!(pe_signal(None), "no data");
+        assert_eq!(pe_signal(Some(7.9)), "deep value");
+        assert_eq!(pe_signal(Some(14.9)), "undervalued");
+        assert_eq!(pe_signal(Some(24.9)), "fairly valued");
+        assert_eq!(pe_signal(Some(39.9)), "premium");
+        assert_eq!(pe_signal(Some(40.0)), "expensive");
+
+        assert_eq!(pb_signal(Some(0.9)), "deep value");
+        assert_eq!(pb_signal(Some(1.9)), "undervalued");
+        assert_eq!(pb_signal(Some(3.9)), "fairly valued");
+        assert_eq!(pb_signal(Some(4.0)), "expensive");
+
+        assert_eq!(roe_signal(Some(0.20)), "excellent");
+        assert_eq!(roe_signal(Some(0.15)), "strong");
+        assert_eq!(roe_signal(Some(0.10)), "adequate");
+        assert_eq!(roe_signal(Some(0.0)), "weak");
+        assert_eq!(roe_signal(Some(-0.01)), "negative");
+
+        assert_eq!(margin_signal(Some(0.20)), "excellent");
+        assert_eq!(margin_signal(Some(0.10)), "healthy");
+        assert_eq!(margin_signal(Some(0.05)), "adequate");
+        assert_eq!(margin_signal(Some(0.0)), "thin");
+        assert_eq!(margin_signal(Some(-0.01)), "negative");
+
+        assert_eq!(ev_ebitda_signal(Some(7.9)), "undervalued");
+        assert_eq!(ev_ebitda_signal(Some(13.9)), "fairly valued");
+        assert_eq!(ev_ebitda_signal(Some(19.9)), "premium");
+        assert_eq!(ev_ebitda_signal(Some(20.0)), "expensive");
+    }
+
+    #[test]
+    fn risk_signal_thresholds_match_python() {
+        assert_eq!(de_signal(None), "no data");
+        assert_eq!(de_signal(Some(-1.0)), "negative equity");
+        assert_eq!(de_signal(Some(49.9)), "conservative");
+        assert_eq!(de_signal(Some(99.9)), "moderate");
+        assert_eq!(de_signal(Some(199.9)), "leveraged");
+        assert_eq!(de_signal(Some(200.0)), "highly leveraged");
+
+        assert_eq!(cr_signal(None), "no data");
+        assert_eq!(cr_signal(Some(2.0)), "strong");
+        assert_eq!(cr_signal(Some(1.5)), "adequate");
+        assert_eq!(cr_signal(Some(1.0)), "tight");
+        assert_eq!(cr_signal(Some(0.99)), "weak");
+    }
+
+    #[test]
+    fn report_overalls_match_python_logic() {
+        let fundamentals = sample_fundamentals();
+
+        let growth = analyze_growth(&fundamentals);
+        assert_eq!(growth.overall_signal, "growing");
+
+        let valuation = analyze_valuation(&fundamentals);
+        assert_eq!(valuation.overall_signal, "undervalued");
+        assert_eq!(valuation.ev_ebitda, Some(8.0));
+
+        let risk = analyze_risk(&fundamentals);
+        assert_eq!(risk.overall_signal, "low risk");
+
+        let fundamental = analyze_fundamental("BBCA.JK", &fundamentals);
+        assert_eq!(fundamental.overall_signal, "healthy");
+    }
+
+    #[test]
+    fn incomplete_growth_and_high_risk_paths_match_python_logic() {
+        let mut fundamentals = sample_fundamentals();
+        fundamentals.revenue_growth = None;
+        fundamentals.earnings_growth = Some(0.05);
+        fundamentals.debt_to_equity = Some(250.0);
+        fundamentals.current_ratio = Some(0.9);
+
+        let growth = analyze_growth(&fundamentals);
+        assert_eq!(growth.overall_signal, "incomplete data");
+
+        let risk = analyze_risk(&fundamentals);
+        assert_eq!(risk.overall_signal, "high risk");
+    }
+}

crates/idx-core/src/analysis/mod.rs

@@ -0,0 +1,3 @@
+pub mod fundamental;
+pub mod signals;
+pub mod technical;

crates/idx-core/src/analysis/signals.rs

@@ -0,0 +1,102 @@
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+pub enum Signal {
+    Bullish,
+    Bearish,
+    Neutral,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct TechnicalSignal {
+    pub rsi: Signal,
+    pub macd: Signal,
+    pub trend: Signal,
+    pub overall: Signal,
+}
+
+pub fn interpret_rsi(value: f64) -> Signal {
+    if value > 70.0 {
+        Signal::Bearish
+    } else if value < 30.0 {
+        Signal::Bullish
+    } else {
+        Signal::Neutral
+    }
+}
+
+pub fn interpret_macd(histogram: f64, prev_histogram: Option<f64>) -> Signal {
+    if let Some(prev) = prev_histogram {
+        if histogram > 0.0 && histogram > prev {
+            Signal::Bullish
+        } else if histogram < 0.0 && histogram < prev {
+            Signal::Bearish
+        } else {
+            Signal::Neutral
+        }
+    } else {
+        Signal::Neutral
+    }
+}
+
+pub fn interpret_trend(price: f64, sma50: Option<f64>, sma200: Option<f64>) -> Signal {
+    match (sma50, sma200) {
+        (Some(s50), Some(s200)) if price > s50 && price > s200 => Signal::Bullish,
+        (Some(s50), Some(s200)) if price < s50 && price < s200 => Signal::Bearish,
+        _ => Signal::Neutral,
+    }
+}
+
+pub fn overall_signal(rsi: Signal, macd: Signal, trend: Signal) -> Signal {
+    let signals = [rsi, macd, trend];
+    let bullish = signals.iter().filter(|&&s| s == Signal::Bullish).count();
+    let bearish = signals.iter().filter(|&&s| s == Signal::Bearish).count();
+
+    if bullish >= 2 {
+        Signal::Bullish
+    } else if bearish >= 2 {
+        Signal::Bearish
+    } else {
+        Signal::Neutral
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn interpret_rsi_thresholds() {
+        assert_eq!(interpret_rsi(75.0), Signal::Bearish);
+        assert_eq!(interpret_rsi(25.0), Signal::Bullish);
+        assert_eq!(interpret_rsi(50.0), Signal::Neutral);
+    }
+
+    #[test]
+    fn interpret_trend_thresholds() {
+        assert_eq!(
+            interpret_trend(120.0, Some(100.0), Some(110.0)),
+            Signal::Bullish
+        );
+        assert_eq!(
+            interpret_trend(80.0, Some(100.0), Some(90.0)),
+            Signal::Bearish
+        );
+    }
+
+    #[test]
+    fn overall_majority_vote() {
+        assert_eq!(
+            overall_signal(Signal::Bullish, Signal::Bullish, Signal::Neutral),
+            Signal::Bullish
+        );
+        assert_eq!(
+            overall_signal(Signal::Bearish, Signal::Neutral, Signal::Bearish),
+            Signal::Bearish
+        );
+        assert_eq!(
+            overall_signal(Signal::Bullish, Signal::Bearish, Signal::Neutral),
+            Signal::Neutral
+        );
+    }
+}

crates/idx-core/src/analysis/technical.rs

@@ -0,0 +1,212 @@
+use serde::Serialize;
+
+#[derive(Debug, Clone, Serialize)]
+pub struct MacdResult {
+    pub macd_line: Vec<Option<f64>>,
+    pub signal_line: Vec<Option<f64>>,
+    pub histogram: Vec<Option<f64>>,
+}
+
+pub fn sma(data: &[f64], period: usize) -> Vec<Option<f64>> {
+    let mut result = vec![None; data.len()];
+    if period == 0 || period > data.len() {
+        return result;
+    }
+
+    let mut window_sum: f64 = data[..period].iter().sum();
+    result[period - 1] = Some(window_sum / period as f64);
+
+    for idx in period..data.len() {
+        window_sum += data[idx] - data[idx - period];
+        result[idx] = Some(window_sum / period as f64);
+    }
+
+    result
+}
+
+pub fn ema(data: &[f64], period: usize) -> Vec<Option<f64>> {
+    let mut result = vec![None; data.len()];
+    if period == 0 || period > data.len() {
+        return result;
+    }
+
+    let multiplier = 2.0 / (period as f64 + 1.0);
+    let seed = data[..period].iter().sum::<f64>() / period as f64;
+    result[period - 1] = Some(seed);
+
+    let mut prev = seed;
+    for idx in period..data.len() {
+        let current = ((data[idx] - prev) * multiplier) + prev;
+        result[idx] = Some(current);
+        prev = current;
+    }
+
+    result
+}
+
+pub fn rsi(closes: &[f64], period: usize) -> Vec<Option<f64>> {
+    let mut result = vec![None; closes.len()];
+    if period == 0 || closes.len() <= period {
+        return result;
+    }
+
+    let mut gains = 0.0;
+    let mut losses = 0.0;
+
+    for idx in 1..=period {
+        let change = closes[idx] - closes[idx - 1];
+        if change >= 0.0 {
+            gains += change;
+        } else {
+            losses += -change;
+        }
+    }
+
+    let mut avg_gain = gains / period as f64;
+    let mut avg_loss = losses / period as f64;
+
+    result[period] = Some(rsi_from_averages(avg_gain, avg_loss));
+
+    for idx in (period + 1)..closes.len() {
+        let change = closes[idx] - closes[idx - 1];
+        let gain = if change > 0.0 { change } else { 0.0 };
+        let loss = if change < 0.0 { -change } else { 0.0 };
+
+        avg_gain = ((avg_gain * (period as f64 - 1.0)) + gain) / period as f64;
+        avg_loss = ((avg_loss * (period as f64 - 1.0)) + loss) / period as f64;
+
+        result[idx] = Some(rsi_from_averages(avg_gain, avg_loss));
+    }
+
+    result
+}
+
+fn rsi_from_averages(avg_gain: f64, avg_loss: f64) -> f64 {
+    if avg_loss == 0.0 {
+        return 100.0;
+    }
+
+    let rs = avg_gain / avg_loss;
+    100.0 - (100.0 / (1.0 + rs))
+}
+
+pub fn macd(closes: &[f64], fast: usize, slow: usize, signal: usize) -> MacdResult {
+    let len = closes.len();
+    let mut macd_line = vec![None; len];
+    let mut signal_line = vec![None; len];
+    let mut histogram = vec![None; len];
+
+    if len == 0 || fast == 0 || slow == 0 || signal == 0 {
+        return MacdResult {
+            macd_line,
+            signal_line,
+            histogram,
+        };
+    }
+
+    let fast_ema = ema(closes, fast);
+    let slow_ema = ema(closes, slow);
+
+    for idx in 0..len {
+        if let (Some(f), Some(s)) = (fast_ema[idx], slow_ema[idx]) {
+            macd_line[idx] = Some(f - s);
+        }
+    }
+
+    let mut signal_seed = Vec::new();
+    let signal_multiplier = 2.0 / (signal as f64 + 1.0);
+    let mut prev_signal = None;
+
+    for idx in 0..len {
+        if let Some(value) = macd_line[idx] {
+            if prev_signal.is_none() {
+                signal_seed.push(value);
+                if signal_seed.len() == signal {
+                    let seed = signal_seed.iter().sum::<f64>() / signal as f64;
+                    signal_line[idx] = Some(seed);
+                    prev_signal = Some(seed);
+                    histogram[idx] = Some(value - seed);
+                }
+            } else if let Some(prev) = prev_signal {
+                let current = ((value - prev) * signal_multiplier) + prev;
+                signal_line[idx] = Some(current);
+                prev_signal = Some(current);
+                histogram[idx] = Some(value - current);
+            }
+        }
+    }
+
+    MacdResult {
+        macd_line,
+        signal_line,
+        histogram,
+    }
+}
+
+pub fn volume_ratio(volumes: &[f64], period: usize) -> Option<f64> {
+    if period == 0 || volumes.len() < period {
+        return None;
+    }
+
+    let start = volumes.len() - period;
+    let avg = volumes[start..].iter().sum::<f64>() / period as f64;
+    if avg == 0.0 {
+        return None;
+    }
+
+    volumes.last().map(|last| *last / avg)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn approx_eq(left: f64, right: f64, eps: f64) {
+        assert!((left - right).abs() <= eps, "left={left}, right={right}");
+    }
+
+    #[test]
+    fn sma_returns_expected_values() {
+        let data = [1.0, 2.0, 3.0, 4.0, 5.0];
+        let values = sma(&data, 3);
+        assert_eq!(values, vec![None, None, Some(2.0), Some(3.0), Some(4.0)]);
+    }
+
+    #[test]
+    fn rsi_returns_seeded_none_and_known_value() {
+        // Classic Wilder example dataset; RSI(14) first computed value ~= 70.46.
+        let closes = [
+            44.34, 44.09, 44.15, 43.61, 44.33, 44.83, 45.10, 45.42, 45.84, 46.08, 45.89, 46.03,
+            45.61, 46.28, 46.28,
+        ];
+        let period = 14;
+        let values = rsi(&closes, period);
+
+        assert_eq!(values.len(), closes.len());
+        assert!(values.iter().take(period).all(Option::is_none));
+
+        let rsi_14 = values[period].expect("expected first RSI value");
+        approx_eq(rsi_14, 70.46, 0.05);
+    }
+
+    #[test]
+    fn macd_shapes_are_correct() {
+        let closes: Vec<f64> = (1..=60).map(|n| n as f64).collect();
+        let result = macd(&closes, 12, 26, 9);
+
+        assert_eq!(result.macd_line.len(), closes.len());
+
+        let macd_nones = result.macd_line.iter().filter(|v| v.is_none()).count();
+        let signal_nones = result.signal_line.iter().filter(|v| v.is_none()).count();
+        assert!(signal_nones > macd_nones);
+    }
+
+    #[test]
+    fn volume_ratio_checks() {
+        let volumes = [100.0, 120.0, 130.0, 150.0];
+        let ratio = volume_ratio(&volumes, 3).expect("ratio should exist");
+        approx_eq(ratio, 150.0 / ((120.0 + 130.0 + 150.0) / 3.0), 1e-10);
+
+        assert_eq!(volume_ratio(&volumes, 5), None);
+    }
+}