From 2aa24f3f3d0c1d921214a8120a54010ffa1befcd Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 19 Feb 2026 01:43:52 +0000
Subject: [PATCH 1/4] Initial plan


From 3cecbd67cc435ea51e6336567e69460b616570b6 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 19 Feb 2026 01:48:15 +0000
Subject: [PATCH 2/4] Remove unused pydantic_numpy import from spectrum.py

Co-authored-by: tomdurrant <11531133+tomdurrant@users.noreply.github.com>
---
 src/rompy/core/spectrum.py | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/rompy/core/spectrum.py b/src/rompy/core/spectrum.py
index f041d263..dd0108a7 100644
--- a/src/rompy/core/spectrum.py
+++ b/src/rompy/core/spectrum.py
@@ -3,7 +3,6 @@
 
 import numpy as np
 from pydantic import Field, model_validator
-from pydantic_numpy.typing import Np1DArray
 
 from rompy.core.types import RompyBaseModel
 
@@ -13,10 +12,12 @@
 class Frequency(RompyBaseModel):
     """Wave frequency."""
 
+    model_config = {"arbitrary_types_allowed": True}
+
     model_type: Literal["frequency", "FREQUENCY"] = Field(
         default="frequency", description="Model type discriminator"
     )
-    freq: Np1DArray = Field(description="Frequency array")
+    freq: np.ndarray = Field(description="Frequency array")
 
     @property
     def f0(self):
@@ -109,7 +110,7 @@ def init_options(self) -> "LogFrequency":
 
         return self
 
-    def __call__(self) -> Np1DArray:
+    def __call__(self) -> np.ndarray:
         """Frequency array."""
         return np.geomspace(self.f0, self.f1, self.nf)
 

From 7433a3f2b9d7c641425a28ba98611f0063724a5e Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 19 Feb 2026 01:49:38 +0000
Subject: [PATCH 3/4] Replace numpy array types with list to avoid arbitrary
 types

Co-authored-by: tomdurrant <11531133+tomdurrant@users.noreply.github.com>
---
 src/rompy/core/spectrum.py | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/src/rompy/core/spectrum.py b/src/rompy/core/spectrum.py
index dd0108a7..8d078d63 100644
--- a/src/rompy/core/spectrum.py
+++ b/src/rompy/core/spectrum.py
@@ -12,24 +12,22 @@
 class Frequency(RompyBaseModel):
     """Wave frequency."""
 
-    model_config = {"arbitrary_types_allowed": True}
-
     model_type: Literal["frequency", "FREQUENCY"] = Field(
         default="frequency", description="Model type discriminator"
     )
-    freq: np.ndarray = Field(description="Frequency array")
+    freq: list = Field(description="Frequency array")
 
     @property
     def f0(self):
-        return self.freq.min()
+        return np.array(self.freq).min()
 
     @property
     def f1(self):
-        return self.freq.max()
+        return np.array(self.freq).max()
 
     @property
     def nf(self):
-        return self.freq.size
+        return len(self.freq)
 
     @property
     def flen(self):
@@ -110,7 +108,7 @@ def init_options(self) -> "LogFrequency":
 
         return self
 
-    def __call__(self) -> np.ndarray:
+    def __call__(self):
         """Frequency array."""
         return np.geomspace(self.f0, self.f1, self.nf)
 

From 49447f3fc78380d5719e2085a33692147bc80783 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 19 Feb 2026 01:50:19 +0000
Subject: [PATCH 4/4] Improve type annotation to list[float] for better type
 safety

Co-authored-by: tomdurrant <11531133+tomdurrant@users.noreply.github.com>
---
 src/rompy/core/spectrum.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/rompy/core/spectrum.py b/src/rompy/core/spectrum.py
index 8d078d63..0edc8718 100644
--- a/src/rompy/core/spectrum.py
+++ b/src/rompy/core/spectrum.py
@@ -15,7 +15,7 @@ class Frequency(RompyBaseModel):
     model_type: Literal["frequency", "FREQUENCY"] = Field(
         default="frequency", description="Model type discriminator"
     )
-    freq: list = Field(description="Frequency array")
+    freq: list[float] = Field(description="Frequency array")
 
     @property
     def f0(self):