From ff025f445d42145fba17d2d17cd5805966642675 Mon Sep 17 00:00:00 2001
From: Katharine Hyatt <kslimes@gmail.com>
Date: Tue, 29 Sep 2026 17:18:36 +0200
Subject: [PATCH 1/3] Restore custom rule for twist to calm 1.10

---
 ext/TensorKitEnzymeExt/indexmanipulations.jl | 51 ++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/ext/TensorKitEnzymeExt/indexmanipulations.jl b/ext/TensorKitEnzymeExt/indexmanipulations.jl
index e93c06dac..873b87905 100644
--- a/ext/TensorKitEnzymeExt/indexmanipulations.jl
+++ b/ext/TensorKitEnzymeExt/indexmanipulations.jl
@@ -116,6 +116,57 @@ function EnzymeRules.reverse(
     return nothing, nothing, nothing, nothing, Δαr, Δβr, map(Returns(nothing), ba)...
 end
 
+# Differentiating through the fusion tree loop corrupts the
+# heap on Julia 1.10 and causes segfaults in the GC. Remove this
+# custom rule when we drop support for 1.10
+function EnzymeRules.augmented_primal(
+        config::EnzymeRules.RevConfigWidth{1},
+        func::Const{typeof(twist!)},
+        ::Type{RT},
+        t::Annotation{<:AbstractTensorMap},
+        inds::Const;
+        inv::Bool = false
+    ) where {RT}
+    twist!(t.val, inds.val; inv)
+    primal = EnzymeRules.needs_primal(config) ? t.val : nothing
+    shadow = EnzymeRules.needs_shadow(config) ? t.dval : nothing
+    return EnzymeRules.AugmentedReturn(primal, shadow, nothing)
+end
+
+function EnzymeRules.reverse(
+        config::EnzymeRules.RevConfigWidth{1},
+        func::Const{typeof(twist!)},
+        ::Type{RT},
+        cache,
+        t::Annotation{<:AbstractTensorMap},
+        inds::Const;
+        inv::Bool = false
+    ) where {RT}
+    !isa(t, Const) && twist!(t.dval, inds.val; inv = !inv)
+    return (nothing, nothing)
+end
+
+function EnzymeRules.forward(
+        config::EnzymeRules.FwdConfigWidth{1},
+        func::Const{typeof(twist!)},
+        ::Type{RT},
+        t::Annotation{<:AbstractTensorMap},
+        inds::Const;
+        inv::Bool = false
+    ) where {RT}
+    twist!(t.val, inds.val; inv)
+    !isa(t, Const) && twist!(t.dval, inds.val; inv)
+    if EnzymeRules.needs_primal(config) && EnzymeRules.needs_shadow(config)
+        return Duplicated(t.val, t.dval)
+    elseif EnzymeRules.needs_primal(config)
+        return t.val
+    elseif EnzymeRules.needs_shadow(config)
+        return t.dval
+    else
+        return nothing
+    end
+end
+
 function EnzymeRules.augmented_primal(
         config::EnzymeRules.RevConfigWidth{1},
         func::Const{typeof(flip)},

From b1ce85faadce2954be87a6d8da09ebc41baf5e80 Mon Sep 17 00:00:00 2001
From: Katharine Hyatt <katharine.s.hyatt@gmail.com>
Date: Tue, 29 Sep 2026 19:51:53 +0200
Subject: [PATCH 2/3] Loosen annotation type for twist fwd rule

---
 ext/TensorKitEnzymeExt/indexmanipulations.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ext/TensorKitEnzymeExt/indexmanipulations.jl b/ext/TensorKitEnzymeExt/indexmanipulations.jl
index 873b87905..0e531f286 100644
--- a/ext/TensorKitEnzymeExt/indexmanipulations.jl
+++ b/ext/TensorKitEnzymeExt/indexmanipulations.jl
@@ -151,7 +151,7 @@ function EnzymeRules.forward(
         func::Const{typeof(twist!)},
         ::Type{RT},
         t::Annotation{<:AbstractTensorMap},
-        inds::Const;
+        inds::Annotation;
         inv::Bool = false
     ) where {RT}
     twist!(t.val, inds.val; inv)

From 32e342606eac84212b4866b1106019db6ca4476d Mon Sep 17 00:00:00 2001
From: Katharine Hyatt <khyatt@flatironinstitute.org>
Date: Wed, 30 Sep 2026 03:17:37 -0400
Subject: [PATCH 3/3] Bump Enzyme compat

---
 Project.toml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Project.toml b/Project.toml
index 83093ea5b..49cb54457 100644
--- a/Project.toml
+++ b/Project.toml
@@ -51,7 +51,7 @@ Adapt = "4"
 CUDA = "6"
 ChainRulesCore = "1"
 Dictionaries = "0.4"
-Enzyme = "0.13.195"
+Enzyme = "0.13.207"
 EnzymeTestUtils = "0.2.8"
 FiniteDifferences = "0.12"
 GPUArrays = "11.4.1"