diff --git a/README.md b/README.md
index cf3e8a2..73e68ed 100644
--- a/README.md
+++ b/README.md
@@ -11,6 +11,8 @@ This repository provides sourceable Bash libraries for scripts that want
 consistent logging, command execution, filesystem editing, Git helper behavior,
 and import conventions without adopting the full Base workspace control plane.
 
+Requires Bash 4.2+. On macOS, use Homebrew Bash instead of the system `/bin/bash`.
+
 ## Libraries
 
 - [`lib/bash/std/lib_std.sh`](lib/bash/std/README.md)
diff --git a/lib/bash/file/lib_file.sh b/lib/bash/file/lib_file.sh
index 6ef864c..aedfa90 100644
--- a/lib/bash/file/lib_file.sh
+++ b/lib/bash/file/lib_file.sh
@@ -245,7 +245,6 @@ update_file_section() {
                 return 0
             fi
         else
-            # FIX: This awk script now correctly handles multiple sections. It only replaces the first one.
             if awk -v START_M="$beginning_marker" -v END_M="$end_marker" -v NEW_TEXT_FILE="$new_content_file" '
             BEGIN {
                 processed = 0 # 0 = not yet processed, 1 = processing, 2 = done
diff --git a/lib/bash/std/lib_std.sh b/lib/bash/std/lib_std.sh
index e29456f..cd4efab 100644
--- a/lib/bash/std/lib_std.sh
+++ b/lib/bash/std/lib_std.sh
@@ -73,6 +73,8 @@ unset -f __lib_std_require_supported_bash__
 __stdlib_sourced__=1
 readonly __LIB_STD_PATH__="${BASH_SOURCE[0]}"
 
+# lib_std.sh lives at lib/bash/std/lib_std.sh in the packaged repository.
+# Walking three levels up reaches the package root that owns VERSION.
 __BASE_BASH_LIBS_ROOT__="$(
     cd -- "$(dirname -- "$__LIB_STD_PATH__")/../../.." &>/dev/null && pwd -P
 )" || {
@@ -1005,8 +1007,14 @@ assert_integer_range() {
     if ! __is_valid_variable_name__ "$var_name"; then
         fatal_error "assert_integer_range expects a variable name as its first argument."
     fi
+    if ! [[ "$min" =~ ^[-+]?[0-9]+$ ]]; then
+        fatal_error "assert_integer_range minimum bound '$min' is not a valid integer."
+    fi
+    if ! [[ "$max" =~ ^[-+]?[0-9]+$ ]]; then
+        fatal_error "assert_integer_range maximum bound '$max' is not a valid integer."
+    fi
     local value="${!var_name-}"
-    assert_integer "$var_name" min max
+    assert_integer "$var_name"
     ((value < min || value > max)) && fatal_error "Variable '$var_name' ($value) is out of range [$min, $max]."
     return 0
 }
diff --git a/lib/bash/std/tests/lib_std.bats b/lib/bash/std/tests/lib_std.bats
index 71f4465..5052970 100644
--- a/lib/bash/std/tests/lib_std.bats
+++ b/lib/bash/std/tests/lib_std.bats
@@ -1128,6 +1128,36 @@ EOF
     [[ "$output" != *"invalid variable name"* ]]
 }
 
+@test "assert_integer_range rejects non-integer bounds directly" {
+    local script="$TEST_TMPDIR/assert-range-bounds.sh"
+
+    create_script "$script" <<EOF
+#!/usr/bin/env bash
+source "$STDLIB_PATH"
+count=5
+assert_integer_range count low 10
+EOF
+
+    bats_run bash "$script"
+
+    [ "$status" -eq 1 ]
+    [[ "$output" == *"assert_integer_range minimum bound 'low' is not a valid integer."* ]]
+    [[ "$output" != *"Variable 'min'"* ]]
+
+    create_script "$script" <<EOF
+#!/usr/bin/env bash
+source "$STDLIB_PATH"
+count=5
+assert_integer_range count 1 high
+EOF
+
+    bats_run bash "$script"
+
+    [ "$status" -eq 1 ]
+    [[ "$output" == *"assert_integer_range maximum bound 'high' is not a valid integer."* ]]
+    [[ "$output" != *"Variable 'max'"* ]]
+}
+
 @test "assert_arg_count accepts exact and ranged matches" {
     assert_arg_count 2 2
     assert_arg_count 2 1 3
diff --git a/tests/validate.sh b/tests/validate.sh
index 150f5db..50b69c5 100755
--- a/tests/validate.sh
+++ b/tests/validate.sh
@@ -49,6 +49,17 @@ if ! grep -F "| \`$version\` | [Apache-2.0](LICENSE) |" README.md >/dev/null; th
   exit 1
 fi
 
+if ! sed -n '1,30p' README.md | grep -F 'Requires Bash 4.2+' >/dev/null; then
+  printf 'README.md must state the Bash 4.2+ requirement near the top-level entry point.\n' >&2
+  exit 1
+fi
+
+fix_comments="$(grep -R -n '# FIX:' lib/bash || true)"
+if [[ -n "$fix_comments" ]]; then
+  printf 'Production library files must not contain development # FIX: comments:\n%s\n' "$fix_comments" >&2
+  exit 1
+fi
+
 for command in shellcheck bats; do
   command -v "$command" >/dev/null 2>&1 || {
     printf "Required validation command '%s' was not found.\n" "$command" >&2