diff --git a/AGENTS.md b/AGENTS.md
index b9aaae27..35271e0c 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -151,8 +151,9 @@ ripwire . --recall="<topic>" # the docs/design and .ripwire_notes rows that answ
 
 1. **hwp-model depends on no other internal crate** (hub and spoke). `hwp5` and `hwpx` do not depend
    on each other either; they go through the IR. `hwp-convert` and `hwp-render` do not depend on
-   each other. These are normal-dependency edges; dev-dependencies are allowed (hwp5's tests use
-   hwpx, hwp-render's use hwp-convert). `scripts/check-crate-edges.sh` checks them.
+   each other. These are normal-dependency edges, direct or transitive; dev-dependencies are
+   allowed (hwp5's tests use hwpx, hwp-render's use hwp-convert). `scripts/check-crate-edges.sh`
+   checks them.
 2. **Lossless round-trip gate**: hwp5 → hwp5 identity re-serialization must be byte-identical
    (`crates/hwp5/tests/identity.rs`). Do not drop unknown records; preserve them as `OpaqueRecord`.
 3. **Ground-truth methodology - no guessing**: format behavior is established only by comparing
diff --git a/REVIEW.md b/REVIEW.md
index 902b4da2..9463a890 100644
--- a/REVIEW.md
+++ b/REVIEW.md
@@ -17,7 +17,7 @@ Run these passes and tag every finding with its pass:
 
 - **Crate direction**: `hwp-model` depends on no other internal crate; `hwp5` and `hwpx` never depend
   on each other and go through the IR; `hwp-convert` and `hwp-render` never depend on each other.
-  These are normal-dependency edges; dev-dependencies are allowed.
+  These are normal-dependency edges, direct or transitive; dev-dependencies are allowed.
 - **Lossless round-trip**: hwp5 -> hwp5 identity re-serialization stays byte-identical; unknown
   records are preserved as `OpaqueRecord`, never dropped.
 - **Ground truth, no guessing**: format behavior is established against bytes written by Hangul, and
diff --git a/scripts/check-crate-edges.sh b/scripts/check-crate-edges.sh
index 33d0ede0..e8a92c0e 100755
--- a/scripts/check-crate-edges.sh
+++ b/scripts/check-crate-edges.sh
@@ -8,6 +8,9 @@
 # added between them would quietly make the duplication pointless. Until now nothing in the
 # repository stopped one; the invariant lived only in prose.
 #
+# The whole normal-dependency tree is checked, not only direct edges (#407): hwp-render taking a
+# normal dependency on hwpx would pull in hwp-convert through hwpx -> hwp-convert.
+#
 # Dev-dependencies are deliberately out of scope (`-e normal`): hwp-render's tests already use
 # hwp-convert to build documents, which does not put either crate in the other's build graph.
 #
@@ -18,30 +21,83 @@ set -uo pipefail
 cd "$(dirname "$0")/.." || exit
 
 fail=0
+manifest=Cargo.toml
 
-# Direct normal dependencies of a crate, one name per line.
+# Normal dependencies of a crate, direct and transitive, one name per line. A cargo failure is a
+# nonzero status with cargo's error left on stderr, never an empty list that reads as "ok".
 deps() {
-    cargo tree -p "$1" -e normal --depth 1 --prefix none 2>/dev/null |
-        tail -n +2 | awk '{print $1}'
+    local tree
+    tree="$(cargo tree -q --manifest-path "$manifest" -p "$1" -e normal --prefix none)" || return
+    printf '%s\n' "$tree" | tail -n +2 | awk '{print $1}' | sort -u
+}
+
+# Status 0 if the crate depends on a name matching the pattern, 1 if not, 2 if cargo tree failed.
+# The match reads a here-string, not a pipe: under pipefail `... | grep -q` can turn a hit into a
+# failure (SIGPIPE upstream), and `grep -c` exits 1 on a zero count.
+has_dep() {
+    local names
+    names="$(deps "$1")" || return 2
+    grep -Eqx "$2" <<<"$names"
 }
 
 forbid() {
-    local crate="$1" forbidden="$2" count
-    count="$(deps "$crate" | grep -Ecx "$forbidden")"
-    if [ "$count" -ne 0 ]; then
-        echo "FAIL: $crate has a normal dependency on $forbidden (AGENTS.md invariant 1)" >&2
+    local crate="$1" forbidden="$2"
+    has_dep "$crate" "$forbidden"
+    case $? in
+    0)
+        echo "FAIL: $crate depends on $forbidden, directly or transitively" \
+            "(AGENTS.md invariant 1)" >&2
         fail=1
-    else
-        echo "ok: $crate does not depend on $forbidden"
-    fi
+        ;;
+    1) echo "ok: $crate does not depend on $forbidden" ;;
+    *)
+        echo "FAIL: cargo tree failed for $crate, so its edges were not checked" >&2
+        fail=1
+        ;;
+    esac
 }
 
 if [ "${1:-}" = "--self-test" ]; then
     # The gate must be able to fail: a dependency that demonstrably exists has to be caught.
-    if deps hwp-cli | grep -Ecx 'hwp-render' | grep -qx 0; then
+    if ! has_dep hwp-cli hwp-render; then
         echo "FAIL: self-test could not see hwp-cli -> hwp-render, so the matcher is broken" >&2
         exit 1
     fi
+    # No internal crate reaches another only transitively today, so a throwaway workspace
+    # supplies the case: edge-a -> edge-b -> edge-c, with no direct edge-a -> edge-c.
+    fixture="$(mktemp -d)"
+    trap 'rm -rf "$fixture"' EXIT
+    printf '[workspace]\nmembers = ["edge-a", "edge-b", "edge-c"]\nresolver = "2"\n' \
+        >"$fixture/Cargo.toml"
+    for c in a b c; do
+        mkdir -p "$fixture/edge-$c/src"
+        : >"$fixture/edge-$c/src/lib.rs"
+        printf '[package]\nname = "edge-%s"\nversion = "0.0.0"\nedition = "2021"\n' "$c" \
+            >"$fixture/edge-$c/Cargo.toml"
+    done
+    printf '[dependencies]\nedge-b = { path = "../edge-b" }\n' >>"$fixture/edge-a/Cargo.toml"
+    printf '[dependencies]\nedge-c = { path = "../edge-c" }\n' >>"$fixture/edge-b/Cargo.toml"
+    manifest="$fixture/Cargo.toml"
+    if ! has_dep edge-a edge-c; then
+        echo "FAIL: self-test missed the transitive edge edge-a -> edge-b -> edge-c" >&2
+        exit 1
+    fi
+    echo "ok: self-test caught the transitive edge edge-a -> edge-b -> edge-c"
+    # forbid() must turn both a hit and a cargo failure into a gate failure. The hit case is only
+    # meaningful after has_dep above has shown cargo works on the fixture.
+    fail=0
+    forbid edge-a edge-c 2>/dev/null
+    if [ "$fail" -ne 1 ]; then
+        echo "FAIL: self-test: forbid() did not fail on a forbidden edge" >&2
+        exit 1
+    fi
+    fail=0
+    forbid no-such-crate edge-c 2>/dev/null
+    if [ "$fail" -ne 1 ]; then
+        echo "FAIL: self-test: forbid() did not fail when cargo tree failed" >&2
+        exit 1
+    fi
+    echo "ok: self-test saw forbid() fail on a forbidden edge and on a cargo tree failure"
     echo "== crate-edges self-test: OK =="
     exit 0
 fi