diff --git a/autogalaxy/analysis/jax_pytrees.py b/autogalaxy/analysis/jax_pytrees.py
new file mode 100644
index 00000000..cfc03305
--- /dev/null
+++ b/autogalaxy/analysis/jax_pytrees.py
@@ -0,0 +1,41 @@
+"""Shared JAX pytree registrations for autogalaxy analysis classes.
+
+Each ``Analysis*`` class registers its own ``Fit*`` and per-analysis
+constants inline (so the call site stays self-documenting), but the
+``Galaxies`` registration is shared from here because the custom
+flatten/unflatten logic is non-trivial and identical across all
+analyses that hold a ``Galaxies`` aggregate.
+"""
+
+
+def register_galaxies_pytree() -> None:
+    """Register ``Galaxies`` as a JAX pytree.
+
+    ``Galaxies`` is a ``list`` subclass — the generic ``__dict__`` flatten
+    in ``register_instance_pytree`` would drop the list contents. This
+    registers a custom flatten that carries the list items as dynamic
+    children and the ``__dict__`` entries as aux.
+
+    Idempotent — guarded by ``_pytree_registered_classes`` so repeated
+    calls (e.g. from each ``Analysis*.fit_from``) are cheap.
+    """
+    from autoarray.abstract_ndarray import _pytree_registered_classes
+    from autoconf.jax_wrapper import register_pytree_node
+    from autogalaxy.galaxy.galaxies import Galaxies
+
+    if Galaxies in _pytree_registered_classes:
+        return
+
+    def _flatten_galaxies(galaxies):
+        dict_items = tuple(sorted(galaxies.__dict__.items()))
+        return tuple(galaxies), dict_items
+
+    def _unflatten_galaxies(aux, children):
+        new = Galaxies.__new__(Galaxies)
+        list.__init__(new, children)
+        for key, value in aux:
+            setattr(new, key, value)
+        return new
+
+    register_pytree_node(Galaxies, _flatten_galaxies, _unflatten_galaxies)
+    _pytree_registered_classes.add(Galaxies)
diff --git a/autogalaxy/imaging/model/analysis.py b/autogalaxy/imaging/model/analysis.py
index d6610a32..f24e45bd 100644
--- a/autogalaxy/imaging/model/analysis.py
+++ b/autogalaxy/imaging/model/analysis.py
@@ -175,37 +175,16 @@ def _register_fit_imaging_pytrees() -> None:
         else (``galaxies``, ``dataset_model`` and the autoarray wrappers they
         carry) is dynamic per fit.
         """
-        from autoarray.abstract_ndarray import (
-            _pytree_registered_classes,
-            register_instance_pytree,
-        )
+        from autoarray.abstract_ndarray import register_instance_pytree
         from autoarray.dataset.dataset_model import DatasetModel
-        from autoconf.jax_wrapper import register_pytree_node
-        from autogalaxy.galaxy.galaxies import Galaxies
+        from autogalaxy.analysis.jax_pytrees import register_galaxies_pytree
 
         register_instance_pytree(
             FitImaging,
             no_flatten=("dataset", "adapt_images", "settings"),
         )
         register_instance_pytree(DatasetModel)
-
-        # ``Galaxies`` is a ``list`` subclass — the generic ``__dict__`` flatten
-        # in ``register_instance_pytree`` would drop the list contents. Register
-        # a custom flatten that carries the list items as dynamic children.
-        if Galaxies not in _pytree_registered_classes:
-            def _flatten_galaxies(galaxies):
-                dict_items = tuple(sorted(galaxies.__dict__.items()))
-                return tuple(galaxies), dict_items
-
-            def _unflatten_galaxies(aux, children):
-                new = Galaxies.__new__(Galaxies)
-                list.__init__(new, children)
-                for key, value in aux:
-                    setattr(new, key, value)
-                return new
-
-            register_pytree_node(Galaxies, _flatten_galaxies, _unflatten_galaxies)
-            _pytree_registered_classes.add(Galaxies)
+        register_galaxies_pytree()
 
     def save_attributes(self, paths: af.DirectoryPaths):
         """
diff --git a/autogalaxy/interferometer/model/analysis.py b/autogalaxy/interferometer/model/analysis.py
index d45e6da6..2d0be29d 100644
--- a/autogalaxy/interferometer/model/analysis.py
+++ b/autogalaxy/interferometer/model/analysis.py
@@ -142,6 +142,10 @@ def fit_from(self, instance: af.ModelInstance) -> FitInterferometer:
         FitInterferometer
             The fit of the galaxies to the interferometer dataset, which includes the log likelihood.
         """
+
+        if self._use_jax:
+            self._register_fit_interferometer_pytrees()
+
         galaxies = self.galaxies_via_instance_from(
             instance=instance,
         )
@@ -158,6 +162,27 @@ def fit_from(self, instance: af.ModelInstance) -> FitInterferometer:
             xp=self._xp,
         )
 
+    @staticmethod
+    def _register_fit_interferometer_pytrees() -> None:
+        """Register every type reachable from a ``FitInterferometer`` return
+        value so ``jax.jit(fit_from)`` can flatten its output.
+
+        ``dataset``, ``adapt_images`` and ``settings`` are constants per
+        analysis — ride as aux so JAX does not recurse into them. Everything
+        else (``galaxies`` and the autoarray wrappers it carries) is dynamic
+        per fit.
+        """
+        from autoarray.abstract_ndarray import register_instance_pytree
+        from autoarray.dataset.dataset_model import DatasetModel
+        from autogalaxy.analysis.jax_pytrees import register_galaxies_pytree
+
+        register_instance_pytree(
+            FitInterferometer,
+            no_flatten=("dataset", "adapt_images", "settings"),
+        )
+        register_instance_pytree(DatasetModel)
+        register_galaxies_pytree()
+
     def save_attributes(self, paths: af.DirectoryPaths):
         """
         Before the model-fit begins, this routine saves attributes of the `Analysis` object to the `files` folder