Completes expansion-roadmap block **A2 — Market Breadth**: the 14 indicators that remained after the `AdvanceDecline` bootstrap, all built on the existing `CrossSection` input.
## Indicators (all scalar `Indicator<Input = CrossSection, Output = f64>`)
| Indicator | Reading |
|-----------|---------|
| `AdvanceDeclineRatio` | advancers / decliners |
| `AdVolumeLine` | cumulative net advancing volume |
| `McClellanOscillator` | 19/39 EMAs of ratio-adjusted net advances |
| `McClellanSummationIndex` | running total of the oscillator |
| `Trin` (Arms Index) | A/D ratio over up/down volume ratio |
| `BreadthThrust` (Zweig) | SMA of the advancing-issues share |
| `NewHighsNewLows` | new highs − new lows |
| `HighLowIndex` | SMA of the record-high percent |
| `PercentAboveMa` | % of the universe above its MA |
| `UpDownVolumeRatio` | advancing / declining volume |
| `BullishPercentIndex` | % on a point-and-figure buy signal |
| `CumulativeVolumeIndex` | volume-normalised cumulative net advancing volume |
| `AbsoluteBreadthIndex` | \|advancers − decliners\| |
| `TickIndex` | instantaneous net advancers − decliners |
## Input model
`AdVolumeLine` and `CumulativeVolumeIndex` are kept distinct (the latter normalises each tick's net advancing volume by total volume, so it stays comparable across volume regimes). `PercentAboveMa` and `BullishPercentIndex` need a per-symbol state signal that `Member` did not carry, so `Member` gains two additive flags (`above_ma`, `on_buy_signal`) via a new `Member::with_signals` constructor; the 4-arg `Member::new` leaves both cleared, so every existing caller and binding is unchanged. `CrossSection` gains volume / new-extreme / state aggregation helpers.
## Wiring
Fully wired across the Rust core, the python/node/wasm bindings, the cross-section fuzz target, the README + docs indicator counters (325 → 339), and dedicated python/node streaming-vs-batch tests. `fmt` / `test --workspace --all-features` / `clippy --workspace -D warnings` / node build+test / pytest all green locally.
kingchenc