diff --git a/scripts/magic_run_common.sh.in b/scripts/magic_run_common.sh.in
index 7795cd74..e6e190eb 100644
--- a/scripts/magic_run_common.sh.in
+++ b/scripts/magic_run_common.sh.in
@@ -138,6 +138,26 @@ magic_stage() {
     ln -sfn "$s"/magic/bitmaps                            "$MAGIC_TCL"/bitmaps 2>/dev/null || :
 }
 
+# Split a launcher's argv on the first "--":
+#     <tool-opts...> -- <magic-args...>
+# Everything before "--" is for the wrapper tool (gdb/valgrind); everything after
+# is magic's.  With no "--" present, ALL arguments are treated as magic's -- the
+# common case where no tool options are needed.  Results are returned in the
+# arrays MAGIC_TOOL_OPTS and MAGIC_ARGS.
+magic_split_args() {
+    MAGIC_TOOL_OPTS=()
+    MAGIC_ARGS=()
+    local seen=0 a
+    for a in "$@"; do
+        if [ "$seen" -eq 0 ] && [ "$a" = "--" ]; then seen=1; continue; fi
+        if [ "$seen" -eq 1 ]; then MAGIC_ARGS+=("$a"); else MAGIC_TOOL_OPTS+=("$a"); fi
+    done
+    if [ "$seen" -eq 0 ]; then
+        MAGIC_ARGS=(${MAGIC_TOOL_OPTS[@]+"${MAGIC_TOOL_OPTS[@]}"})
+        MAGIC_TOOL_OPTS=()
+    fi
+}
+
 # Fail early with a clear message if the build has not produced the binaries yet.
 magic_require_built() {
     if [ ! -x "$MAGIC_BUILDDIR/tcltk/magicexec" ] && \
diff --git a/scripts/run_magic_gdb.sh.in b/scripts/run_magic_gdb.sh.in
index 30d49136..0ef96dd3 100644
--- a/scripts/run_magic_gdb.sh.in
+++ b/scripts/run_magic_gdb.sh.in
@@ -9,12 +9,20 @@
 #   "magicexec".  Symbols come straight from the build tree.
 #
 # USAGE
-#   ./run_magic_gdb.sh [magic-args...]        # then `run` at the (gdb) prompt
-#   For batch/no-GUI debugging (no X display needed, reproducible), debug the null
-#   binary instead:
-#     gdb --args "$MAGIC_TCL/magicdnull" -dnull -nowrapper
+#   ./run_magic_gdb.sh [gdb-opts...] [-- [magic-args...]]
+#
+#   A "--" separates gdb's own options from magic's:
+#       ./run_magic_gdb.sh                         # plain interactive gdb
+#       ./run_magic_gdb.sh foo.mag                 # no "--" => all args go to magic
+#       ./run_magic_gdb.sh -tui -- foo.mag         # gdb gets -tui, magic gets foo.mag
+#       ./run_magic_gdb.sh -ex run -- -dnull       # gdb runs immediately; magic -dnull
+#   With no "--", every argument is passed to magic (the common case).
+#
+#   For batch/no-GUI debugging point it at the null device:  ... -- -dnull
 #
 # ENVIRONMENT OVERRIDES (all optional; each wins over the baked default)
+#   GDB         debugger binary to use (default: gdb on PATH)
+#   GDB_OPTS    default gdb options, prepended before any given on the command line
 #   CAD_ROOT    reuse an alternate runtime tree instead of staging $builddir/CAD_DIR
 #   MAGIC_WISH  wish for the Tk console (default: the configure-matched wish)
 #   WISH TCLSH  wish/tclsh matching this build's Tcl/Tk (--with-tk / --with-tcl)
@@ -25,7 +33,15 @@ set -eu
 here="$(cd "$(dirname "$0")" && pwd)"
 . "$here/magic_run_common.sh"
 
+GDB="${GDB:-gdb}"
+command -v "$GDB" >/dev/null 2>&1 || magic_warn "debugger '$GDB' not found on PATH"
+
 magic_require_built
 magic_stage
+magic_split_args "$@"
 
-exec gdb --args "$MAGIC_TCL/magicexec" -- "$@"
+# gdb <opts> --args magicexec -- <magic-args>
+exec "$GDB" ${GDB_OPTS-} \
+    ${MAGIC_TOOL_OPTS[@]+"${MAGIC_TOOL_OPTS[@]}"} \
+    --args "$MAGIC_TCL/magicexec" -- \
+    ${MAGIC_ARGS[@]+"${MAGIC_ARGS[@]}"}
diff --git a/scripts/run_magic_valgrind.sh.in b/scripts/run_magic_valgrind.sh.in
index ba6c09a9..be524b83 100644
--- a/scripts/run_magic_valgrind.sh.in
+++ b/scripts/run_magic_valgrind.sh.in
@@ -9,12 +9,23 @@
 #   valgrind on the self-contained "magicexec".
 #
 # USAGE
-#   ./run_magic_valgrind.sh [magic-args...]
-#   This checks the GUI binary (magicexec); Tk/X allocations make the output
-#   noisy, so for real leak hunting prefer the batch binary (fewer moving parts):
-#     valgrind --leak-check=full "$MAGIC_TCL/magicdnull" -dnull -nowrapper
+#   ./run_magic_valgrind.sh [valgrind-opts...] [-- [magic-args...]]
+#
+#   A "--" separates valgrind's own options from magic's:
+#       ./run_magic_valgrind.sh                       # default memcheck options
+#       ./run_magic_valgrind.sh foo.mag               # no "--" => all args go to magic
+#       ./run_magic_valgrind.sh -v -- foo.mag         # valgrind -v, magic gets foo.mag
+#       ./run_magic_valgrind.sh --tool=callgrind --   # a different valgrind tool
+#   With no "--", every argument is passed to magic (the common case).
+#
+#   This checks the GUI binary; Tk/X allocations make the output noisy, so for
+#   real leak hunting run the batch device:  ./run_magic_valgrind.sh -- -dnull
 #
 # ENVIRONMENT OVERRIDES (all optional; each wins over the baked default)
+#   VALGRIND       valgrind binary to use (default: valgrind on PATH)
+#   VALGRIND_OPTS  default valgrind options (default: --leak-check=full
+#                  --error-exitcode=0).  Set empty to clear them; command-line
+#                  options before "--" are added after these.
 #   CAD_ROOT    reuse an alternate runtime tree instead of staging $builddir/CAD_DIR
 #   MAGIC_WISH  wish for the Tk console (default: the configure-matched wish)
 #   WISH TCLSH  wish/tclsh matching this build's Tcl/Tk (--with-tk / --with-tcl)
@@ -25,8 +36,16 @@ set -eu
 here="$(cd "$(dirname "$0")" && pwd)"
 . "$here/magic_run_common.sh"
 
+VALGRIND="${VALGRIND:-valgrind}"
+command -v "$VALGRIND" >/dev/null 2>&1 || magic_warn "valgrind '$VALGRIND' not found on PATH"
+VALGRIND_OPTS="${VALGRIND_OPTS---leak-check=full --error-exitcode=0}"
+
 magic_require_built
 magic_stage
+magic_split_args "$@"
 
-exec valgrind --leak-check=full --error-exitcode=0 \
-    "$MAGIC_TCL/magicexec" -- "$@"
+# valgrind <opts> magicexec -- <magic-args>
+exec "$VALGRIND" $VALGRIND_OPTS \
+    ${MAGIC_TOOL_OPTS[@]+"${MAGIC_TOOL_OPTS[@]}"} \
+    "$MAGIC_TCL/magicexec" -- \
+    ${MAGIC_ARGS[@]+"${MAGIC_ARGS[@]}"}