diff --git a/sp1/guest/Cargo.toml b/sp1/guest/Cargo.toml
index 9caf0540..08ac0864 100644
--- a/sp1/guest/Cargo.toml
+++ b/sp1/guest/Cargo.toml
@@ -1,3 +1,13 @@
+# Standalone workspace root. This guest crate is compiled out-of-tree for
+# the zkVM target and never joins the host Cargo workspace; its own (empty)
+# `[workspace]` pins cargo's upward workspace search to this directory.
+# Without it, a NESTED checkout — e.g. the benchmark base-run, which checks
+# the base repo out under `base/` inside the PR checkout — lets cargo walk
+# past the relative `exclude` paths in the outer manifests and resolve this
+# crate to the outer workspace, failing the build script with "current
+# package believes it's in a workspace when it's not".
+[workspace]
+
 [package]
 name = "sp1-guest"
 version = "0.1.0"
diff --git a/zisk/agg-guest/Cargo.toml b/zisk/agg-guest/Cargo.toml
index 5f7d55e5..a20515c9 100644
--- a/zisk/agg-guest/Cargo.toml
+++ b/zisk/agg-guest/Cargo.toml
@@ -1,3 +1,13 @@
+# Standalone workspace root. This guest crate is compiled out-of-tree for
+# the zkVM target and never joins the host Cargo workspace; its own (empty)
+# `[workspace]` pins cargo's upward workspace search to this directory.
+# Without it, a NESTED checkout — e.g. the benchmark base-run, which checks
+# the base repo out under `base/` inside the PR checkout — lets cargo walk
+# past the relative `exclude` paths in the outer manifests and resolve this
+# crate to the outer workspace, failing the build script with "current
+# package believes it's in a workspace when it's not".
+[workspace]
+
 [package]
 name = "zisk-agg-guest"
 version = "0.1.0"
diff --git a/zisk/guest/Cargo.toml b/zisk/guest/Cargo.toml
index 060b5f52..fe3b6e2b 100644
--- a/zisk/guest/Cargo.toml
+++ b/zisk/guest/Cargo.toml
@@ -1,3 +1,13 @@
+# Standalone workspace root. This guest crate is compiled out-of-tree for
+# the zkVM target and never joins the host Cargo workspace; its own (empty)
+# `[workspace]` pins cargo's upward workspace search to this directory.
+# Without it, a NESTED checkout — e.g. the benchmark base-run, which checks
+# the base repo out under `base/` inside the PR checkout — lets cargo walk
+# past the relative `exclude` paths in the outer manifests and resolve this
+# crate to the outer workspace, failing the build script with "current
+# package believes it's in a workspace when it's not".
+[workspace]
+
 [package]
 name = "zisk-guest"
 version = "0.1.0"