From 24f1dc8716ea610c98c13034fcb7b49c27a6530d Mon Sep 17 00:00:00 2001
From: Mayank Lavania <mayank.lavania@gmail.com>
Date: Mon, 13 Jul 2026 22:07:41 +0530
Subject: [PATCH] fix(python): constructable GaussianHmmParamsPy + dict-like
 backtest metrics (nhkk)

Two record-port gaps from the uniffi->PyO3 migration, surfaced by relocating the
previously-CI-invisible tests:

1. GaussianHmmParamsPy is an INPUT params record that Python constructs
   (qw.GaussianHmmParamsPy(n_states=..., delta=..., ...)), but the ported
   #[pyclass(get_all)] had no #[new], so construction raised "No constructor
   defined". Add a #[new] (lambdas defaults to empty = Gaussian mode). Audited all
   49 records: this is the only one Python constructs; the rest are read-only outputs.

2. PerformanceMetrics / BacktestStats define __getitem__(str) + keys() but no
   __contains__, so `"sharpe_ratio" in metrics` fell back to integer-index iteration
   (getattr(self, 0)) -> "TypeError: attribute name must be string, not 'int'".
   Add __contains__ and __iter__ so they behave dict-like.

Fixes test_hmm_forecast (2), test_ml_feature_backtest_parity, test_strategy_backtest.
Full suite 6 -> 2 failures (remaining: pandas-only benchmark test + a stale
LazyFrame.ta test_parity, both unrelated).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
---
 .../python/quantwave/backtest_types.py        | 18 ++++++++++++--
 quantwave-py/src/indicators.rs                | 24 +++++++++++++++++++
 2 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/quantwave-py/python/quantwave/backtest_types.py b/quantwave-py/python/quantwave/backtest_types.py
index 793fbfc82..b8c0a6760 100644
--- a/quantwave-py/python/quantwave/backtest_types.py
+++ b/quantwave-py/python/quantwave/backtest_types.py
@@ -28,10 +28,18 @@ def as_dict(self) -> dict[str, float]:
         
     def keys(self):
         return self.as_dict().keys()
-        
+
     def __getitem__(self, key: str):
         return getattr(self, key)
 
+    def __contains__(self, key: object) -> bool:
+        # Without this, ``"x" in metrics`` falls back to integer-index iteration
+        # via __getitem__ (getattr(self, 0)) and raises TypeError.
+        return isinstance(key, str) and key in self.as_dict()
+
+    def __iter__(self):
+        return iter(self.keys())
+
 @dataclass(frozen=True)
 class BacktestStats:
     """Core summary statistics from a backtest run."""
@@ -50,6 +58,12 @@ def as_dict(self) -> dict[str, float]:
         
     def keys(self):
         return self.as_dict().keys()
-        
+
     def __getitem__(self, key: str):
         return getattr(self, key)
+
+    def __contains__(self, key: object) -> bool:
+        return isinstance(key, str) and key in self.as_dict()
+
+    def __iter__(self):
+        return iter(self.keys())
diff --git a/quantwave-py/src/indicators.rs b/quantwave-py/src/indicators.rs
index b6d8bcf1c..52baefde9 100644
--- a/quantwave-py/src/indicators.rs
+++ b/quantwave-py/src/indicators.rs
@@ -1883,6 +1883,30 @@ pub struct GaussianHmmParamsPy {
     /// Per-state λ (empty → 1.0 per state, Gaussian mode).
     pub lambdas: Vec<f64>,
 }
+#[pymethods]
+impl GaussianHmmParamsPy {
+    // Constructable from Python (input params, not a read-only result record):
+    // `qw.GaussianHmmParamsPy(n_states, delta, gamma_flat, means, stds, lambdas=[])`.
+    #[new]
+    #[pyo3(signature = (n_states, delta, gamma_flat, means, stds, lambdas = Vec::new()))]
+    pub fn new(
+        n_states: u32,
+        delta: Vec<f64>,
+        gamma_flat: Vec<f64>,
+        means: Vec<f64>,
+        stds: Vec<f64>,
+        lambdas: Vec<f64>,
+    ) -> Self {
+        Self {
+            n_states,
+            delta,
+            gamma_flat,
+            means,
+            stds,
+            lambdas,
+        }
+    }
+}
 
 #[pyclass(get_all)]
 #[derive(Clone)]