diff --git a/.Rbuildignore b/.Rbuildignore
index 232504f..388f1c6 100644
--- a/.Rbuildignore
+++ b/.Rbuildignore
@@ -22,3 +22,4 @@
 ^\.jules(/.*)?$
 ^\.trivyignore\.yaml$
 ^trivy\.yaml$
+^\.semgrepignore$
diff --git a/.jules/sentinel.md b/.jules/sentinel.md
index a8207a4..7d5925e 100644
--- a/.jules/sentinel.md
+++ b/.jules/sentinel.md
@@ -2,3 +2,8 @@
 **Vulnerability:** Unvalidated inputs passed to `if()` statements can cause process crashes (`condition has length > 1`) or unexpected coercion vulnerabilities.
 **Learning:** In R, optional boolean parameters that default to `NULL` should be validated using explicit runtime type validation (e.g., `if (!is.null(flag) && (!is.logical(flag) || length(flag) != 1 || is.na(flag)))`).
 **Prevention:** Always implement explicit runtime type validation for optional boolean parameters.
+
+## 2024-08-02 - Fix integer coercion DoS vulnerability
+**Vulnerability:** Weak regex `^[0-9]+$` on interactive `readline()` user inputs allows huge numeric strings which coerce to `NA` when passed to `as.integer()`.
+**Learning:** In R, evaluating `NA` inside an `if()` condition or returning `NA` from a function expected to return integers can break program logic or crash automation processes.
+**Prevention:** Use strictly bounded exact-match regex like `^[12]$` when validating integer inputs intended to be explicitly mapped to fixed choices.
diff --git a/DESCRIPTION b/DESCRIPTION
index f31d3e1..c90753c 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -10,7 +10,7 @@ Description: Automates fixed item parameter linking for test linking under
     the item response theory paradigm using mirt package estimates.
 License: GPL-3 | file LICENSE
 Imports: mirt, methods
-Suggests: testthat (>= 3.0.0)
+Suggests: testthat (>= 3.0.0), mockery
 Encoding: UTF-8
 Config/testthat/edition: 3
 Config/roxygen2/version: 8.0.0
diff --git a/R/aFIPC.R b/R/aFIPC.R
index 6254651..918e19b 100644
--- a/R/aFIPC.R
+++ b/R/aFIPC.R
@@ -141,7 +141,7 @@ autoFIPC <-
       }
       for (attempt in seq_len(3)) {
         n <- readline(prompt = "Is it correct? (1: Yes 2: No) : ")
-        if (grepl("^[0-9]+$", n)) {
+        if (grepl("^[12]$", n)) {
           return(as.integer(n))
         }
       }
@@ -171,7 +171,7 @@ autoFIPC <-
               readline(
                 prompt = "Do you want to use default BILOG-MG priors for oldform Data? (1: Yes 2: No) : "
               )
-            if (grepl("^[0-9]+$", n)) {
+            if (grepl("^[12]$", n)) {
               return(as.integer(n))
             }
           }
@@ -390,7 +390,7 @@ autoFIPC <-
               readline(
                 prompt = "Do you want to use default BILOG-MG priors for newform Data? (1: Yes 2: No) : "
               )
-            if (grepl("^[0-9]+$", n)) {
+            if (grepl("^[12]$", n)) {
               return(as.integer(n))
             }
           }
diff --git a/test_dummy.R b/test_dummy.R
deleted file mode 100644
index e6f7019..0000000
--- a/test_dummy.R
+++ /dev/null
@@ -1,2 +0,0 @@
-source("R/aFIPC.R")
-source("R/surveyFA.R")
diff --git a/test_validation.R b/test_validation.R
deleted file mode 100644
index f084116..0000000
--- a/test_validation.R
+++ /dev/null
@@ -1,3 +0,0 @@
-source("R/aFIPC.R")
-source("R/surveyFA.R")
-print("Syntax check passed")
diff --git a/tests/testthat/test-sentinel-validation.R b/tests/testthat/test-sentinel-validation.R
index 900f0ee..dafde55 100644
--- a/tests/testthat/test-sentinel-validation.R
+++ b/tests/testthat/test-sentinel-validation.R
@@ -35,3 +35,46 @@ test_that("autoFIPC validates boolean flags for newformBILOGprior, oldformBILOGp
     "Security Error: confirmCommonItems must be a single non-NA logical value or NULL"
   )
 })
+
+test_that("autoFIPC integer validation works with strictly bounded regex", {
+  # Mock readline to return invalid inputs that should fail after 3 attempts
+  # override interactive() to TRUE to trigger the readline loop, then mock readline
+  with_mockery <- function() {
+    mockery::stub(aFIPC::autoFIPC, 'interactive', TRUE)
+    mockery::stub(aFIPC::autoFIPC, 'readline', mockery::mock('3', '0', '999999999'))
+    expect_error(
+      aFIPC::autoFIPC(
+        newformXData = data.frame(A=1, B=2),
+        oldformYData = data.frame(A=1, B=2),
+        newformCommonItemNames = c('A', 'B'),
+        oldformCommonItemNames = c('A', 'B'),
+        confirmCommonItems = NULL
+      ),
+      "Too many invalid common item confirmation attempts"
+    )
+  }
+  with_mockery()
+})
+
+test_that("autoFIPC integer validation accepts valid inputs", {
+  # Mock readline to return '1' (valid input)
+  with_mockery_valid <- function() {
+    mockery::stub(aFIPC::autoFIPC, 'interactive', TRUE)
+    mockery::stub(aFIPC::autoFIPC, 'readline', '1')
+    mockery::stub(aFIPC::autoFIPC, 'mirt::mirt', function(...) stop('forced failure'))
+    mockery::stub(aFIPC::autoFIPC, 'surveyFA', function(...) stop('forced failure'))
+
+    expect_error(
+      aFIPC::autoFIPC(
+        newformXData = data.frame(A=1, B=2),
+        oldformYData = data.frame(A=1, B=2),
+        newformCommonItemNames = c('A', 'B'),
+        oldformCommonItemNames = c('A', 'B'),
+        confirmCommonItems = NULL,
+        oldformBILOGprior = NULL,
+        newformBILOGprior = NULL
+      )
+    )
+  }
+  with_mockery_valid()
+})