diff --git a/CHANGELOG.md b/CHANGELOG.md
index f085bad..c5e9aa5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,13 @@
 
 Notable user-visible changes are recorded here, newest first.
 
+## Unreleased
+
+- Upgrade llm-sketchkit to v0.2.3 for parser allocation limits, more efficient
+  summary combination and safer secret/error diagnostics. Keep the existing
+  x/text v0.41.0 normalization dependency, identities and summary wire format.
+  This is the hardening backport; the v0.3.0 identity migration is separate.
+
 ## [0.6.0] - 2026-10-11
 
 See the [release notes](docs/releases/v0.6.0.md) for the LiteLLM workflow and
diff --git a/go.mod b/go.mod
index 1bf8104..4b9b4bc 100644
--- a/go.mod
+++ b/go.mod
@@ -3,7 +3,7 @@ module github.com/llm-measurement/fleetdiff
 go 1.26.0
 
 require (
-	github.com/llm-measurement/llm-sketchkit v0.2.2
+	github.com/llm-measurement/llm-sketchkit v0.2.3
 	go.opentelemetry.io/proto/slim/otlp v1.11.1
 	go.yaml.in/yaml/v3 v3.0.5
 	google.golang.org/protobuf v1.36.12
diff --git a/go.sum b/go.sum
index 3be654e..ed91565 100644
--- a/go.sum
+++ b/go.sum
@@ -1,7 +1,7 @@
 github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
 github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
-github.com/llm-measurement/llm-sketchkit v0.2.2 h1:MtDgc3Gy5Pjbst/ZXQe9YidOVlQ6+X+hbYnjFrtmf8k=
-github.com/llm-measurement/llm-sketchkit v0.2.2/go.mod h1:FfKeuXT6lD9G4wv8Z5KBcHF+q+3odiJfo7mNDZpX52M=
+github.com/llm-measurement/llm-sketchkit v0.2.3 h1:Mz68IIkMro95xGjxYayKSsXLO8e/B7qLTsSjoQstppU=
+github.com/llm-measurement/llm-sketchkit v0.2.3/go.mod h1:FfKeuXT6lD9G4wv8Z5KBcHF+q+3odiJfo7mNDZpX52M=
 go.opentelemetry.io/proto/slim/otlp v1.11.1 h1:qf2OA3kQcIDXh3q7b6kc0IzRe8BFXlVIlH5uaOACrVQ=
 go.opentelemetry.io/proto/slim/otlp v1.11.1/go.mod h1:15pWfj6/rYjQzyrC3ZGQoZ0rNgLqI/Lk+jFgYgV4UIE=
 go.yaml.in/yaml/v3 v3.0.5 h1:N6y/pJk8buWs9NY5ERU2HSMfm+IuD/OtfdAnq6kESPw=