diff --git a/conformance-tests/2023-09/FEATURE_BUNDLE_1/jobs/1.1.1--job-name-512-chars-substitution.test.yaml b/conformance-tests/2023-09/FEATURE_BUNDLE_1/jobs/1.1.1--job-name-512-chars-substitution.test.yaml
new file mode 100644
index 00000000..0d3ff6b5
--- /dev/null
+++ b/conformance-tests/2023-09/FEATURE_BUNDLE_1/jobs/1.1.1--job-name-512-chars-substitution.test.yaml
@@ -0,0 +1,25 @@
+# Spec 1.1.1 <JobName> with FEATURE_BUNDLE_1: max length 512 characters,
+# checked after the format string is resolved. The name resolves to 512
+# characters via {{Param.N}} and must be accepted. The task prints the
+# resolved length so a job-creation failure cannot be reported as a pass.
+template:
+  specificationVersion: jobtemplate-2023-09
+  extensions:
+  - FEATURE_BUNDLE_1
+  name: "{{Param.N}}"
+  parameterDefinitions:
+  - name: N
+    type: STRING
+    default: "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
+  steps:
+  - name: Step1
+    script:
+      actions:
+        onRun:
+          command: python
+          args:
+          - "-c"
+          - "print('OUTPUT:' + str(len(r'{{Param.N}}')))"
+expected:
+  output:
+  - OUTPUT:512
diff --git a/conformance-tests/2023-09/FEATURE_BUNDLE_1/jobs/1.1.1--job-name-513-chars-substitution.invalid.test.yaml b/conformance-tests/2023-09/FEATURE_BUNDLE_1/jobs/1.1.1--job-name-513-chars-substitution.invalid.test.yaml
new file mode 100644
index 00000000..6d8ff2a3
--- /dev/null
+++ b/conformance-tests/2023-09/FEATURE_BUNDLE_1/jobs/1.1.1--job-name-513-chars-substitution.invalid.test.yaml
@@ -0,0 +1,21 @@
+# Spec 1.1.1 <JobName> with FEATURE_BUNDLE_1: max length 512 characters,
+# checked after the format string is resolved. The name resolves to 513
+# characters via {{Param.N}}, so job creation must fail.
+template:
+  specificationVersion: jobtemplate-2023-09
+  extensions:
+  - FEATURE_BUNDLE_1
+  name: "{{Param.N}}"
+  parameterDefinitions:
+  - name: N
+    type: STRING
+    default: "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
+  steps:
+  - name: Step1
+    script:
+      actions:
+        onRun:
+          command: python
+          args:
+          - "-c"
+          - "print()"
diff --git a/conformance-tests/2023-09/base/jobs/1.1.1--job-name-too-long-substitution.invalid.test.yaml b/conformance-tests/2023-09/base/jobs/1.1.1--job-name-too-long-substitution.invalid.test.yaml
new file mode 100644
index 00000000..7816fe88
--- /dev/null
+++ b/conformance-tests/2023-09/base/jobs/1.1.1--job-name-too-long-substitution.invalid.test.yaml
@@ -0,0 +1,20 @@
+# Spec 1.1.1 <JobName>: max length 128 characters, checked after the format
+# string is resolved. The name is a bare {{Param.N}} whose value is 129
+# characters, so job creation must fail even though the template text is
+# short and passes decode.
+template:
+  specificationVersion: jobtemplate-2023-09
+  name: "{{Param.N}}"
+  parameterDefinitions:
+  - name: N
+    type: STRING
+    default: "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
+  steps:
+  - name: Step1
+    script:
+      actions:
+        onRun:
+          command: python
+          args:
+          - "-c"
+          - "print()"