diff --git a/.github/workflows/build_container.yml b/.github/workflows/build_container.yml
index 27c60a6df2..f9f87b6762 100644
--- a/.github/workflows/build_container.yml
+++ b/.github/workflows/build_container.yml
@@ -301,6 +301,11 @@ jobs:
           # can do JSON extraction (reflection) and read OBP props (getenv); without it the sandbox
           # denies these and DynamicResourceDocTest's native-execution scenarios fail.
           echo 'dynamic_code_sandbox_permissions=[new java.net.NetPermission("specifyStreamHandler"), new java.lang.reflect.ReflectPermission("suppressAccessChecks"), new java.lang.RuntimePermission("getenv.*"), new java.util.PropertyPermission("cglib.useCache", "read"), new java.util.PropertyPermission("net.sf.cglib.test.stressHashCodes", "read"), new java.util.PropertyPermission("cglib.debugLocation", "read"), new java.lang.RuntimePermission("accessDeclaredMembers"), new java.lang.RuntimePermission("getClassLoader")]' >> obp-api/src/main/resources/props/test.default.props
+          # allow_user_generated_scala_code defaults to false everywhere (including test/dev)
+          # with no run-mode fallback; CI must opt in explicitly so DynamicUtilTest,
+          # ConnectorMethodTest, AbacRuleTests, DynamicResourceDocTest, DynamicMessageDocTest
+          # and DynamicCodeKillSwitchTest's ON scenarios can still compile/execute dynamic code.
+          echo allow_user_generated_scala_code=true >> obp-api/src/main/resources/props/test.default.props
 
       - name: Run tests — shard ${{ matrix.shard }} (${{ matrix.name }})
         run: |
diff --git a/.github/workflows/build_pull_request.yml b/.github/workflows/build_pull_request.yml
index dbda7f5d3b..39716fe115 100644
--- a/.github/workflows/build_pull_request.yml
+++ b/.github/workflows/build_pull_request.yml
@@ -295,6 +295,11 @@ jobs:
           # can do JSON extraction (reflection) and read OBP props (getenv); without it the sandbox
           # denies these and DynamicResourceDocTest's native-execution scenarios fail.
           echo 'dynamic_code_sandbox_permissions=[new java.net.NetPermission("specifyStreamHandler"), new java.lang.reflect.ReflectPermission("suppressAccessChecks"), new java.lang.RuntimePermission("getenv.*"), new java.util.PropertyPermission("cglib.useCache", "read"), new java.util.PropertyPermission("net.sf.cglib.test.stressHashCodes", "read"), new java.util.PropertyPermission("cglib.debugLocation", "read"), new java.lang.RuntimePermission("accessDeclaredMembers"), new java.lang.RuntimePermission("getClassLoader")]' >> obp-api/src/main/resources/props/test.default.props
+          # allow_user_generated_scala_code defaults to false everywhere (including test/dev)
+          # with no run-mode fallback; CI must opt in explicitly so DynamicUtilTest,
+          # ConnectorMethodTest, AbacRuleTests, DynamicResourceDocTest, DynamicMessageDocTest
+          # and DynamicCodeKillSwitchTest's ON scenarios can still compile/execute dynamic code.
+          echo allow_user_generated_scala_code=true >> obp-api/src/main/resources/props/test.default.props
 
       - name: Run tests — shard ${{ matrix.shard }} (${{ matrix.name }})
         run: |
diff --git a/obp-api/src/main/resources/props/sample.props.template b/obp-api/src/main/resources/props/sample.props.template
index d5616d5621..82b032707d 100644
--- a/obp-api/src/main/resources/props/sample.props.template
+++ b/obp-api/src/main/resources/props/sample.props.template
@@ -1571,7 +1571,8 @@ personal_data_collection_consent_country_waiver_list = Austria, Belgium, Bulgari
 # SECURITY: the runtime sandbox (SecurityManager) is a no-op on JDK 24+ (JEP 486) and the
 # GraalVM JS context is created with HostAccess.ALL, so enabled dynamic code runs UNSANDBOXED.
 # Leave false in production. Only enable on trusted sandbox/dev instances.
-# (Always ON in test/dev run modes regardless of this value, unless this prop is set explicitly.)
+# Defaults to false everywhere (including test/dev run modes) when this prop is absent —
+# it must be set to true explicitly, there is no run-mode-based fallback.
 allow_user_generated_scala_code=false
 
 # enable dynamic code sandbox, default is false, this will make sandbox works for code running in Future, will make performance lower than disable
diff --git a/obp-api/src/main/resources/props/test.default.props.template b/obp-api/src/main/resources/props/test.default.props.template
index 240f3312f9..21f8856d41 100644
--- a/obp-api/src/main/resources/props/test.default.props.template
+++ b/obp-api/src/main/resources/props/test.default.props.template
@@ -147,6 +147,12 @@ allow_public_views =true
 # the 10-thread concurrency tests. Set to 20 to provide headroom.
 hikari.maximumPoolSize=20
 
+# allow_user_generated_scala_code (RCE surface kill-switch) defaults to false everywhere,
+# including test/dev, with no run-mode fallback. Set explicitly here so DynamicUtilTest,
+# ConnectorMethodTest, AbacRuleTests, DynamicResourceDocTest, DynamicMessageDocTest and
+# DynamicCodeKillSwitchTest's ON scenarios can compile/execute dynamic code locally.
+allow_user_generated_scala_code=true
+
 # Permissions granted to runtime-compiled dynamic-endpoint code inside the security sandbox.
 # Mirrors default.props / production.default.props. Required so dynamic resource-doc bodies can do
 # JSON extraction (reflection) and read OBP props (getenv); without it the sandbox denies these and
diff --git a/obp-api/src/main/scala/code/api/util/DynamicUtil.scala b/obp-api/src/main/scala/code/api/util/DynamicUtil.scala
index fdf4fa7661..878e3bc08c 100644
--- a/obp-api/src/main/scala/code/api/util/DynamicUtil.scala
+++ b/obp-api/src/main/scala/code/api/util/DynamicUtil.scala
@@ -32,12 +32,14 @@ import scala.tools.reflect.{ToolBox, ToolBoxError}
 
 object DynamicUtil extends MdcLoggable{
 
-  // Master kill-switch for user-generated dynamic code (RCE surface). Explicit prop always
-  // wins so tests can force OFF; absent the prop, ON in test/dev, OFF in production.
+  // Master kill-switch for user-generated dynamic code (RCE surface). Defaults to OFF
+  // everywhere — including test/dev — unless explicitly enabled via this prop. Tests that
+  // exercise dynamic-code compilation must set allow_user_generated_scala_code=true
+  // explicitly (see test.default.props / the CI "Setup props" step).
   def dynamicCodeExecutionEnabled: Boolean =
     APIUtil.getPropsValue("allow_user_generated_scala_code") match {
       case Full(v) => v.toBoolean
-      case _ => net.liftweb.util.Props.testMode || net.liftweb.util.Props.devMode
+      case _ => false
     }
 
   val toolBox: ToolBox[universe.type] = runtimeMirror(getClass.getClassLoader).mkToolBox()
diff --git a/obp-api/src/test/scala/code/api/v4_0_0/DynamicCodeKillSwitchTest.scala b/obp-api/src/test/scala/code/api/v4_0_0/DynamicCodeKillSwitchTest.scala
index 205987e57f..2baa9aa41e 100644
--- a/obp-api/src/test/scala/code/api/v4_0_0/DynamicCodeKillSwitchTest.scala
+++ b/obp-api/src/test/scala/code/api/v4_0_0/DynamicCodeKillSwitchTest.scala
@@ -58,18 +58,26 @@ class DynamicCodeKillSwitchTest extends V400ServerSetup {
     setPropsValues("connector" -> "star")
   }
 
+  // The predicate defaults to false everywhere (including test/dev) with no run-mode
+  // fallback — it is false unless allow_user_generated_scala_code is explicitly set. This
+  // suite's baseline test.default.props sets it to true explicitly so the ON scenarios
+  // below can compile/execute dynamic code; there is no way, within this harness, to
+  // exercise the truly-absent case, since the base props file always supplies a value once
+  // set. The "absent -> false" branch is what protects deployers who never set the prop at
+  // all — it's covered by direct inspection of DynamicUtil.dynamicCodeExecutionEnabled's
+  // match expression, not by an integration test.
   feature("DynamicUtil.dynamicCodeExecutionEnabled predicate") {
 
-    scenario("Defaults to enabled in test mode when the prop is absent", VersionOfApi) {
-      Then("the predicate should be true (we are running under testMode)")
+    scenario("Explicit prop=true (this suite's baseline) enables compilation", VersionOfApi) {
+      Then("the predicate should be true given the explicit test-props value")
       DynamicUtil.dynamicCodeExecutionEnabled should be(true)
 
-      And("compileScalaCode should still compile and execute")
+      And("compileScalaCode should compile and execute")
       val result = DynamicUtil.compileScalaCode[Int]("41 + 1")
       result should be(Full(42))
     }
 
-    scenario("Explicit prop=false overrides testMode and disables compilation", VersionOfApi) {
+    scenario("Explicit prop=false disables compilation regardless of run mode", VersionOfApi) {
       setPropsValues("allow_user_generated_scala_code" -> "false")
 
       Then("the predicate should be false")
@@ -80,10 +88,13 @@ class DynamicCodeKillSwitchTest extends V400ServerSetup {
       result should be(Failure(DynamicCodeExecutionDisabled))
     }
 
-    scenario("Explicit prop=true overrides a false default", VersionOfApi) {
+    scenario("A later explicit prop=true re-enables after being forced off", VersionOfApi) {
+      setPropsValues("allow_user_generated_scala_code" -> "false")
+      DynamicUtil.dynamicCodeExecutionEnabled should be(false)
+
       setPropsValues("allow_user_generated_scala_code" -> "true")
 
-      Then("the predicate should be true")
+      Then("the predicate should be true again")
       DynamicUtil.dynamicCodeExecutionEnabled should be(true)
     }
   }
diff --git a/run_tests_parallel.sh b/run_tests_parallel.sh
index 4f8e687328..82c72d486c 100755
--- a/run_tests_parallel.sh
+++ b/run_tests_parallel.sh
@@ -278,6 +278,11 @@ run_shard() {
     # OBP_DYNAMIC_CODE_SANDBOX_PERMISSIONS mirrors CI's dynamic_code_sandbox_permissions
     # props line: without it the dynamic-code sandbox denies reflection/getenv and
     # DynamicResourceDocTest's native-execution scenarios fail locally (CI green, local red).
+    # OBP_ALLOW_USER_GENERATED_SCALA_CODE mirrors CI's allow_user_generated_scala_code=true:
+    # the kill-switch defaults to false everywhere (including test/dev) with no run-mode
+    # fallback, so DynamicUtilTest / ConnectorMethodTest / AbacRuleTests /
+    # DynamicResourceDocTest / DynamicMessageDocTest / DynamicCodeKillSwitchTest's ON
+    # scenarios need this set explicitly or they fail locally with OBP-50020.
     # -pl obp-commons,obp-api mirrors CI: obp-commons' own util suites run on whichever
     # shard's filter matches com.openbankproject.* (the shard-4 catch-all); on every other
     # shard the filter matches nothing in obp-commons -> 0 tests there.
@@ -291,6 +296,7 @@ run_shard() {
     OBP_HTTP4S_TEST_PORT="${http4s_port}" \
     OBP_MAIL_TEST_MODE="true" \
     OBP_DYNAMIC_CODE_SANDBOX_PERMISSIONS='[new java.net.NetPermission("specifyStreamHandler"), new java.lang.reflect.ReflectPermission("suppressAccessChecks"), new java.lang.RuntimePermission("getenv.*"), new java.util.PropertyPermission("cglib.useCache", "read"), new java.util.PropertyPermission("net.sf.cglib.test.stressHashCodes", "read"), new java.util.PropertyPermission("cglib.debugLocation", "read"), new java.lang.RuntimePermission("accessDeclaredMembers"), new java.lang.RuntimePermission("getClassLoader")]' \
+    OBP_ALLOW_USER_GENERATED_SCALA_CODE="true" \
     OBP_API_INSTANCE_ID="shard_${n}" \
     "$TIMEOUT_BIN" 1200 mvn scalatest:test -pl obp-commons,obp-api -DfailIfNoTests=false \
         "-DwildcardSuites=${filter}" \