Brummel
d8b2a2880d
Author MACD as a nested composite -- price -> fast/slow EMA -> Sub (MACD line) -> signal EMA -> Sub (histogram), the histogram exposed as the single output the strategy trades. A richer fixture than sma_cross: an EMA-of-EMA chain with interior fan-out (the MACD line feeds both the signal EMA and the histogram), exercising the nested-composite render shipped in cycle 0017. It runs over the real path: the composite blueprint is compiled to a flat harness via compile_with_params + Harness::bootstrap (the same machinery as the SMA compiled view), not hand-flattened. New surfaces: aura run --macd (runs the strategy, prints metrics) and aura graph --macd [--compiled]. main's arg parsing is rewritten to a whole-argv match, preserving the #16 strict contract (trailing token / unknown subcommand -> usage, exit 2). MACD gets its own longer synthetic stream because the SMA-seeded EMAs warm up; the SMA sample's stream and goldens are untouched. This PoC makes two parameter-space gaps concrete for the milestone: the strategy's param_space is [macd.length, macd.length, macd.length, scale] -- three identical names distinguishable only by slot (the named-param case, blueprint #30) -- and a composite exposes only one output port, so the MACD/signal/histogram tuple cannot all be tapped for display (the tuple-output case). The compiled view's valued labels (EMA(2)/EMA(4)/EMA(3)) are what currently disambiguate the three EMAs. Tested: MACD compiles from the nested composite and runs deterministically (C1), the trace is non-trivial (>=1 exposure sign flip), and the blueprint view renders the composite definition once.