From 829373552ae60b98f9107bc78786f709bef3597b Mon Sep 17 00:00:00 2001
From: Fabian Steube <206550910+Flomber@users.noreply.github.com>
Date: Mon, 31 Aug 2026 19:22:46 +0200
Subject: [PATCH 1/6] MAINT: add TypeAlias for CollapseMode in _labels.py

---
 src/qrules/io/_labels.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/qrules/io/_labels.py b/src/qrules/io/_labels.py
index e79f4c82..638ffb63 100644
--- a/src/qrules/io/_labels.py
+++ b/src/qrules/io/_labels.py
@@ -5,7 +5,7 @@
 from fractions import Fraction
 from functools import singledispatch
 from inspect import isfunction
-from typing import TYPE_CHECKING, Any, Protocol
+from typing import TYPE_CHECKING, Any, Literal, Protocol, TypeAlias
 
 import attrs
 
@@ -29,6 +29,7 @@
 
 _LOGGER = logging.getLogger(__name__)
 
+CollapseMode: TypeAlias = Literal["spin", "topology"]
 RenderedGraph = ProblemSet | QNProblemSet | Topology | Transition
 RenderPair = tuple[Topology, RenderedGraph]
 RenderInput = RenderedGraph | RenderPair

From 15e62c819363d944928a9f7e7dc21c40f860e8cf Mon Sep 17 00:00:00 2001
From: Fabian Steube <206550910+Flomber@users.noreply.github.com>
Date: Mon, 31 Aug 2026 19:26:47 +0200
Subject: [PATCH 2/6] MAINT: refactor transition handling to use CollapseMode
 for collapsing options

---
 src/qrules/io/__init__.py | 38 +++++++++++++++++---------------------
 src/qrules/io/_dot.py     | 32 +++++++-------------------------
 src/qrules/io/_labels.py  | 21 +++++++++++++++++++++
 src/qrules/io/_mermaid.py | 18 ++++++------------
 4 files changed, 51 insertions(+), 58 deletions(-)

diff --git a/src/qrules/io/__init__.py b/src/qrules/io/__init__.py
index 07a2018a..f428e745 100644
--- a/src/qrules/io/__init__.py
+++ b/src/qrules/io/__init__.py
@@ -14,10 +14,12 @@
 import attrs
 import yaml
 
-from qrules.io import _dict, _dot, _mermaid
+from qrules.io import _dict, _dot, _labels, _mermaid
 from qrules.particle import Particle, ParticleCollection
 from qrules.topology import Topology
 
+CollapseMode = _labels.CollapseMode
+
 if TYPE_CHECKING:
     from _typeshed import StrPath
 
@@ -62,8 +64,7 @@ def asdot(
     render_final_state_id: bool = True,
     render_resonance_id: bool = False,
     render_initial_state_id: bool = False,
-    strip_spin: bool = False,
-    collapse_graphs: bool = False,
+    collapse: CollapseMode | None = None,
     edge_style: dict[str, Any] | None = None,
     node_style: dict[str, Any] | None = None,
     **figure_style: Any,
@@ -76,12 +77,11 @@ def asdot(
     Args:
         instance: the input `object` that is to be rendered as DOT (graphviz) language.
 
-        strip_spin: Normally, each `.MutableTransition` has a `.Particle` with a spin
-            projection on its edges. This option hides the projections, leaving only
-            `.Particle` names on edges.
-
-        collapse_graphs: Group all transitions by equivalent kinematic topology
-            and combine all allowed particles on each edge.
+        collapse: Optionally combine transitions. With ``"spin"``, transitions that
+            differ only in their spin projections are combined. With ``"topology"``,
+            transitions with equivalent kinematic topologies are grouped and all
+            allowed particles on each edge are collected. Node properties cannot be
+            rendered when collapsing by topology.
 
         render_node: Whether or not to render node ID (in the case of a `.Topology`)
             and/or node properties (in the case of a `.MutableTransition`). Meaning of
@@ -113,8 +113,7 @@ def asdot(
         render_final_state_id=render_final_state_id,
         render_resonance_id=render_resonance_id,
         render_initial_state_id=render_initial_state_id,
-        strip_spin=strip_spin,
-        collapse_graphs=collapse_graphs,
+        collapse=collapse,
         figure_style=figure_style,
         edge_style=edge_style,
         node_style=node_style,
@@ -129,8 +128,7 @@ def asmermaid(
     render_final_state_id: bool = True,
     render_resonance_id: bool = False,
     render_initial_state_id: bool = False,
-    strip_spin: bool = False,
-    collapse_graphs: bool = False,
+    collapse: CollapseMode | None = None,
     figure_style: dict[str, Any] | None = None,
     edge_style: dict[str, Any] | None = None,
     node_style: dict[str, Any] | None = None,
@@ -146,12 +144,11 @@ def asmermaid(
         instance: the input `object` that is to be rendered as Mermaid flowchart
             source.
 
-        strip_spin: Normally, each `.MutableTransition` has a `.Particle` with a spin
-            projection on its edges. This option hides the projections, leaving only
-            `.Particle` names on edges.
-
-        collapse_graphs: Group all transitions by equivalent kinematic topology
-            and combine all allowed particles on each edge.
+        collapse: Optionally combine transitions. With ``"spin"``, transitions that
+            differ only in their spin projections are combined. With ``"topology"``,
+            transitions with equivalent kinematic topologies are grouped and all
+            allowed particles on each edge are collected. Node properties cannot be
+            rendered when collapsing by topology.
 
         render_node: Whether or not to render node ID (in the case of a `.Topology`)
             and/or node properties (in the case of a `.MutableTransition`). Meaning of
@@ -187,8 +184,7 @@ def asmermaid(
         render_final_state_id=render_final_state_id,
         render_resonance_id=render_resonance_id,
         render_initial_state_id=render_initial_state_id,
-        strip_spin=strip_spin,
-        collapse_graphs=collapse_graphs,
+        collapse=collapse,
         figure_style=figure_style,
         edge_style=edge_style,
         node_style=node_style,
diff --git a/src/qrules/io/_dot.py b/src/qrules/io/_dot.py
index 3a063351..6a5dc1b4 100644
--- a/src/qrules/io/_dot.py
+++ b/src/qrules/io/_dot.py
@@ -10,7 +10,7 @@
 from collections import abc
 from typing import TYPE_CHECKING, Any
 
-from attrs import Attribute, define, field
+from attrs import define, field
 from attrs.converters import default_if_none
 
 from qrules.io import _labels
@@ -24,19 +24,6 @@
 _LOGGER = logging.getLogger(__name__)
 
 
-def _check_booleans(
-    instance: GraphvizPrinter,
-    _attribute: Attribute,
-    _value: bool,
-) -> None:
-    if instance.strip_spin and instance.collapse_graphs:
-        msg = "Cannot both strip spin and collapse graphs"
-        raise ValueError(msg)
-    if instance.collapse_graphs and instance.render_node:
-        msg = "Collapsed graphs cannot be rendered with node properties"
-        raise ValueError(msg)
-
-
 def _create_default_figure_style(style: dict[str, Any] | None) -> dict[str, Any]:
     figure_style = {"bgcolor": None}
     if style is None:
@@ -51,8 +38,7 @@ class GraphvizPrinter:
     render_final_state_id: bool = True
     render_resonance_id: bool = False
     render_initial_state_id: bool = False
-    strip_spin: bool = False
-    collapse_graphs: bool = False
+    collapse: _labels.CollapseMode | None = None
 
     figure_style: dict[str, Any] = field(
         converter=_create_default_figure_style, default=None
@@ -97,15 +83,11 @@ def _render(self, obj: Any) -> list[str]:
         raise NotImplementedError(msg)
 
     def _render_multiple_transitions(self, obj: Iterable) -> list[str]:
-        if self.collapse_graphs:
-            transitions: list = _labels.collapse_graphs(obj)
-        elif self.strip_spin:
-            if self.render_node:
-                transitions = sorted({_labels.strip_projections(t) for t in obj})
-            else:
-                transitions = _labels.get_particle_graphs(obj)
-        else:
-            transitions = list(obj)
+        transitions = _labels.prepare_transitions(
+            obj,
+            collapse=self.collapse,
+            render_node=self.render_node,
+        )
         lines = []
         for i, graph in enumerate(reversed(list(transitions))):
             lines += self._render_transition(graph, prefix=f"T{i}_")
diff --git a/src/qrules/io/_labels.py b/src/qrules/io/_labels.py
index 638ffb63..96a3b4a2 100644
--- a/src/qrules/io/_labels.py
+++ b/src/qrules/io/_labels.py
@@ -547,6 +547,27 @@ def get_particle_graphs(
     )
 
 
+def prepare_transitions(
+    transitions: Iterable[Any],
+    *,
+    collapse: CollapseMode | None,
+    render_node: bool | None,
+) -> list[Any]:
+    if collapse is None:
+        return list(transitions)
+    if collapse == "spin":
+        if render_node:
+            return sorted({strip_projections(t) for t in transitions})
+        return get_particle_graphs(transitions)
+    if collapse == "topology":
+        if render_node:
+            msg = "Transitions collapsed by topology cannot render node properties"
+            raise ValueError(msg)
+        return collapse_graphs(transitions)
+    msg = f"Unknown collapse mode {collapse!r}; expected None, 'spin', or 'topology'"
+    raise ValueError(msg)
+
+
 def strip_projections(
     graph: Transition[Any, InteractionProperties],
 ) -> FrozenTransition[Particle, InteractionProperties]:
diff --git a/src/qrules/io/_mermaid.py b/src/qrules/io/_mermaid.py
index 6b6f7d24..c3befcf2 100644
--- a/src/qrules/io/_mermaid.py
+++ b/src/qrules/io/_mermaid.py
@@ -78,8 +78,7 @@ class MermaidPrinter:
     render_final_state_id: bool = True
     render_resonance_id: bool = False
     render_initial_state_id: bool = False
-    strip_spin: bool = False
-    collapse_graphs: bool = False
+    collapse: _labels.CollapseMode | None = None
     figure_style: dict[str, Any] = attrs.field(converter=_to_style_dict, default=None)
     edge_style: dict[str, Any] = attrs.field(converter=_to_style_dict, default=None)
     node_style: dict[str, Any] = attrs.field(converter=_to_style_dict, default=None)
@@ -104,16 +103,11 @@ def _render(self, obj: Any) -> list[str]:
         raise NotImplementedError(msg)
 
     def _render_multiple_transitions(self, obj: Iterable) -> list[str]:
-        transitions: Iterable[Transition[Any, Any]]
-        if self.collapse_graphs:
-            transitions = _labels.collapse_graphs(obj)
-        elif self.strip_spin:
-            if self.render_node:
-                transitions = sorted({_labels.strip_projections(t) for t in obj})
-            else:
-                transitions = _labels.get_particle_graphs(obj)
-        else:
-            transitions = list(obj)
+        transitions = _labels.prepare_transitions(
+            obj,
+            collapse=self.collapse,
+            render_node=self.render_node,
+        )
 
         lines: list[str] = []
         for i, graph in enumerate(reversed(list(transitions))):

From e103b5bca551c1ed6267e3cb0ba3aaf54ad7da22 Mon Sep 17 00:00:00 2001
From: Fabian Steube <206550910+Flomber@users.noreply.github.com>
Date: Mon, 31 Aug 2026 19:29:48 +0200
Subject: [PATCH 3/6] MAINT: update asdot and asmermaid functions to use
 collapse parameter instead of strip_spin and collapse_graphs

---
 tests/unit/io/test_dot.py     |  8 +++----
 tests/unit/io/test_labels.py  | 44 +++++++++++++++++++++++++++++++++++
 tests/unit/io/test_mermaid.py | 10 ++++----
 3 files changed, 53 insertions(+), 9 deletions(-)

diff --git a/tests/unit/io/test_dot.py b/tests/unit/io/test_dot.py
index c45253eb..3bd8916b 100644
--- a/tests/unit/io/test_dot.py
+++ b/tests/unit/io/test_dot.py
@@ -19,9 +19,9 @@ def test_asdot(reaction: ReactionInfo):
         assert is_valid_dot(src)
     src = io.asdot(reaction)
     assert is_valid_dot(src)
-    src = io.asdot(reaction, strip_spin=True)
+    src = io.asdot(reaction, collapse="spin")
     assert is_valid_dot(src)
-    src = io.asdot(reaction, collapse_graphs=True)
+    src = io.asdot(reaction, collapse="topology")
     assert is_valid_dot(src)
 
 
@@ -192,10 +192,10 @@ def test_write_graph_list(self, output_dir: str, reaction: ReactionInfo):
                 src = stream.read()
             assert is_valid_dot(src)
 
-    def test_write_strip_spin(self, output_dir: str, reaction: ReactionInfo):
+    def test_write_collapse_spin(self, output_dir: str, reaction: ReactionInfo):
         output_file = output_dir + "test_particle_graphs.gv"
         io.write(
-            instance=io.asdot(reaction, strip_spin=True),
+            instance=io.asdot(reaction, collapse="spin"),
             filename=output_file,
         )
         with open(output_file) as stream:
diff --git a/tests/unit/io/test_labels.py b/tests/unit/io/test_labels.py
index 09a96c17..c00b9812 100644
--- a/tests/unit/io/test_labels.py
+++ b/tests/unit/io/test_labels.py
@@ -3,6 +3,7 @@
 from textwrap import dedent
 
 import attrs
+import pytest
 
 import qrules
 from qrules.io._labels import (
@@ -11,6 +12,7 @@
     collapse_graphs,
     create_edge_label,
     get_particle_graphs,
+    prepare_transitions,
     strip_projections,
 )
 from qrules.particle import Particle, ParticleCollection
@@ -305,6 +307,48 @@ def test_collapse_graphs(
     assert intermediate_states == f_resonances
 
 
+def test_prepare_transitions(reaction: ReactionInfo):
+    transitions = reaction.transitions
+    assert prepare_transitions(
+        transitions,
+        collapse=None,
+        render_node=False,
+    ) == list(transitions)
+    assert prepare_transitions(
+        transitions,
+        collapse="spin",
+        render_node=False,
+    ) == get_particle_graphs(transitions)
+    assert prepare_transitions(
+        transitions,
+        collapse="spin",
+        render_node=True,
+    ) == sorted({strip_projections(t) for t in transitions})
+    assert prepare_transitions(
+        transitions,
+        collapse="topology",
+        render_node=False,
+    ) == collapse_graphs(transitions)
+
+
+def test_prepare_transitions_rejects_node_properties(reaction: ReactionInfo):
+    with pytest.raises(ValueError, match="cannot render node properties"):
+        prepare_transitions(
+            reaction.transitions,
+            collapse="topology",
+            render_node=True,
+        )
+
+
+def test_prepare_transitions_rejects_unknown_mode(reaction: ReactionInfo):
+    with pytest.raises(ValueError, match="Unknown collapse mode 'invalid'"):
+        prepare_transitions(
+            reaction.transitions,
+            collapse="invalid",  # ty: ignore[invalid-argument-type]
+            render_node=False,
+        )
+
+
 def test_get_particle_graphs(
     reaction: ReactionInfo, particle_database: ParticleCollection
 ):
diff --git a/tests/unit/io/test_mermaid.py b/tests/unit/io/test_mermaid.py
index 02037ca7..f339eac7 100644
--- a/tests/unit/io/test_mermaid.py
+++ b/tests/unit/io/test_mermaid.py
@@ -85,13 +85,13 @@ def test_asmermaid_latex_reaction(reaction: ReactionInfo):
 
 
 def test_asmermaid_latex_collapsed_graph(reaction: ReactionInfo):
-    src = io.asmermaid(reaction, collapse_graphs=True, latex=True)
+    src = io.asmermaid(reaction, collapse="topology", latex=True)
     assert R"$$\begin{gathered} f_{0}(980)" in src
     assert R"\\\ f_{0}(1500) \end{gathered}$$" in src
 
 
-def test_asmermaid_latex_strip_spin(reaction: ReactionInfo):
-    src = io.asmermaid(reaction, strip_spin=True, latex=True)
+def test_asmermaid_latex_collapse_spin(reaction: ReactionInfo):
+    src = io.asmermaid(reaction, collapse="spin", latex=True)
     assert R"J/\psi(1S)$$" in src
     assert R"\gamma$$" in src
     assert R"\left[" not in src
@@ -132,10 +132,10 @@ def test_asmermaid_reaction(reaction: ReactionInfo):
     src = io.asmermaid(reaction, latex=False)
     assert src.startswith("flowchart LR\n")
     assert " --- " in src
-    src = io.asmermaid(reaction, strip_spin=True, latex=False)
+    src = io.asmermaid(reaction, collapse="spin", latex=False)
     assert src.startswith("flowchart LR\n")
     assert " --- " in src
-    src = io.asmermaid(reaction, collapse_graphs=True, latex=False)
+    src = io.asmermaid(reaction, collapse="topology", latex=False)
     assert src.startswith("flowchart LR\n")
     assert " --- " in src
 

From a168b5d5c999d28d915f0e5c67ce13d3be7f94f7 Mon Sep 17 00:00:00 2001
From: Fabian Steube <206550910+Flomber@users.noreply.github.com>
Date: Mon, 31 Aug 2026 19:30:31 +0200
Subject: [PATCH 4/6] MAINT: update GraphvizPrinter to use kw_only for better
 parameter handling

---
 src/qrules/io/_dot.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/qrules/io/_dot.py b/src/qrules/io/_dot.py
index 6a5dc1b4..92256ad8 100644
--- a/src/qrules/io/_dot.py
+++ b/src/qrules/io/_dot.py
@@ -32,7 +32,7 @@ def _create_default_figure_style(style: dict[str, Any] | None) -> dict[str, Any]
     return figure_style
 
 
-@define(on_setattr=_check_booleans)
+@define(kw_only=True)
 class GraphvizPrinter:
     render_node: bool | None = None
     render_final_state_id: bool = True

From b4ff3d7982c3cb290917766f61320d9f080248d3 Mon Sep 17 00:00:00 2001
From: Fabian Steube <206550910+Flomber@users.noreply.github.com>
Date: Mon, 31 Aug 2026 19:34:54 +0200
Subject: [PATCH 5/6] MAINT: update all notebooks to use collapse rather than
 using strip_spin and collapse_graph args

---
 docs/usage.ipynb                 |  2 +-
 docs/usage/custom-topology.ipynb |  6 +++---
 docs/usage/ls-coupling.ipynb     |  2 +-
 docs/usage/reaction.ipynb        |  4 ++--
 docs/usage/visualize.ipynb       | 14 +++++++-------
 5 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/docs/usage.ipynb b/docs/usage.ipynb
index bebf67de..b4cc7853 100644
--- a/docs/usage.ipynb
+++ b/docs/usage.ipynb
@@ -64,7 +64,7 @@
    "source": [
     "from IPython.display import Markdown\n",
     "\n",
-    "source = qrules.io.asmermaid(reaction, collapse_graphs=True, markdown=True)\n",
+    "source = qrules.io.asmermaid(reaction, collapse=\"topology\", markdown=True)\n",
     "Markdown(source)"
    ]
   },
diff --git a/docs/usage/custom-topology.ipynb b/docs/usage/custom-topology.ipynb
index ba27e2c6..1d27912b 100644
--- a/docs/usage/custom-topology.ipynb
+++ b/docs/usage/custom-topology.ipynb
@@ -153,7 +153,7 @@
    },
    "outputs": [],
    "source": [
-    "source = qrules.io.asmermaid(reaction_kk, collapse_graphs=True, markdown=True)\n",
+    "source = qrules.io.asmermaid(reaction_kk, collapse=\"topology\", markdown=True)\n",
     "Markdown(source)"
    ]
   },
@@ -192,7 +192,7 @@
    },
    "outputs": [],
    "source": [
-    "source = qrules.io.asmermaid(reaction_ep, collapse_graphs=True, markdown=True)\n",
+    "source = qrules.io.asmermaid(reaction_ep, collapse=\"topology\", markdown=True)\n",
     "Markdown(source)"
    ]
   },
@@ -231,7 +231,7 @@
    },
    "outputs": [],
    "source": [
-    "source = qrules.io.asmermaid(reaction_ep_no_mass, collapse_graphs=True, markdown=True)\n",
+    "source = qrules.io.asmermaid(reaction_ep_no_mass, collapse=\"topology\", markdown=True)\n",
     "Markdown(source)"
    ]
   }
diff --git a/docs/usage/ls-coupling.ipynb b/docs/usage/ls-coupling.ipynb
index fe1cb927..e1b4e7e8 100644
--- a/docs/usage/ls-coupling.ipynb
+++ b/docs/usage/ls-coupling.ipynb
@@ -277,7 +277,7 @@
     "    allowed_interaction_types=\"strong\",\n",
     "    max_angular_momentum=3,\n",
     ")\n",
-    "source = qrules.io.asmermaid(reaction, markdown=True, render_node=True, strip_spin=True)\n",
+    "source = qrules.io.asmermaid(reaction, collapse=\"spin\", markdown=True, render_node=True)\n",
     "Markdown(source)"
    ]
   }
diff --git a/docs/usage/reaction.ipynb b/docs/usage/reaction.ipynb
index ebf2a254..d61e9365 100644
--- a/docs/usage/reaction.ipynb
+++ b/docs/usage/reaction.ipynb
@@ -379,7 +379,7 @@
    },
    "outputs": [],
    "source": [
-    "source = io.asmermaid(lc2pkpi_reaction, collapse_graphs=True, markdown=True)\n",
+    "source = io.asmermaid(lc2pkpi_reaction, collapse=\"topology\", markdown=True)\n",
     "Markdown(source)"
    ]
   },
@@ -480,7 +480,7 @@
    },
    "outputs": [],
    "source": [
-    "source = io.asmermaid(reaction, collapse_graphs=True, markdown=True, render_node=False)\n",
+    "source = io.asmermaid(reaction, collapse=\"topology\", markdown=True, render_node=False)\n",
     "Markdown(source)"
    ]
   },
diff --git a/docs/usage/visualize.ipynb b/docs/usage/visualize.ipynb
index 6e14c30e..371b536f 100644
--- a/docs/usage/visualize.ipynb
+++ b/docs/usage/visualize.ipynb
@@ -268,7 +268,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "Since this list of all possible spin projections {attr}`~.ReactionInfo.transitions` is rather long, it is often useful to use `strip_spin=True` or `collapse_graphs=True` to bundle comparable graphs. First, {code}`strip_spin=True` allows one collapse (ignore) the spin projections (we again show a selection only):"
+    "Since this list of all possible spin projections {attr}`~.ReactionInfo.transitions` is rather long, it is often useful to collapse comparable graphs. First, {code}`collapse=\"spin\"` allows one to collapse (ignore) the spin projections (we again show a selection only):"
    ]
   },
   {
@@ -278,7 +278,7 @@
    "outputs": [],
    "source": [
     "first_transitions = reaction.transitions[:3]\n",
-    "source = qrules.io.asmermaid(first_transitions, markdown=True, strip_spin=True)\n",
+    "source = qrules.io.asmermaid(first_transitions, collapse=\"spin\", markdown=True)\n",
     "Markdown(source)"
    ]
   },
@@ -299,7 +299,7 @@
     "    first_transitions,\n",
     "    markdown=True,\n",
     "    render_node=True,\n",
-    "    strip_spin=True,\n",
+    "    collapse=\"spin\",\n",
     ")\n",
     "Markdown(source)"
    ]
@@ -317,7 +317,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "If that list is still too much, there is {code}`collapse_graphs=True`, which bundles all graphs with the same final state groupings:"
+    "If that list is still too much, {code}`collapse=\"topology\"` bundles all graphs with the same final state groupings:"
    ]
   },
   {
@@ -327,7 +327,7 @@
    "outputs": [],
    "source": [
     "source = qrules.io.asmermaid(\n",
-    "    reaction, collapse_graphs=True, markdown=True, render_node=False\n",
+    "    reaction, collapse=\"topology\", markdown=True, render_node=False\n",
     ")\n",
     "Markdown(source)"
    ]
@@ -345,7 +345,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "dot = qrules.io.asdot(reaction, collapse_graphs=True, render_node=False)\n",
+    "dot = qrules.io.asdot(reaction, collapse=\"topology\", render_node=False)\n",
     "graphviz.Source(dot)"
    ]
   },
@@ -486,7 +486,7 @@
     "    )\n",
     "    for t in reaction.transitions\n",
     "})\n",
-    "source = qrules.io.asmermaid(jpc_ig_transitions, collapse_graphs=True, markdown=True)\n",
+    "source = qrules.io.asmermaid(jpc_ig_transitions, collapse=\"topology\", markdown=True)\n",
     "Markdown(source)"
    ]
   },

From 87547f1cbfa09a5806e336da204a0f37e3ca845a Mon Sep 17 00:00:00 2001
From: Remco de Boer <29308176+redeboer@users.noreply.github.com>
Date: Mon, 31 Aug 2026 22:13:27 +0200
Subject: [PATCH 6/6] MAINT: minor formatting improvements

---
 src/qrules/io/__init__.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/qrules/io/__init__.py b/src/qrules/io/__init__.py
index f428e745..3f030e0d 100644
--- a/src/qrules/io/__init__.py
+++ b/src/qrules/io/__init__.py
@@ -146,9 +146,9 @@ def asmermaid(
 
         collapse: Optionally combine transitions. With ``"spin"``, transitions that
             differ only in their spin projections are combined. With ``"topology"``,
-            transitions with equivalent kinematic topologies are grouped and all
-            allowed particles on each edge are collected. Node properties cannot be
-            rendered when collapsing by topology.
+            transitions with equivalent kinematic topologies are grouped and all allowed
+            particles on each edge are collected. Node properties cannot be rendered
+            when collapsing by topology.
 
         render_node: Whether or not to render node ID (in the case of a `.Topology`)
             and/or node properties (in the case of a `.MutableTransition`). Meaning of