diff --git a/jenkins/L0_MergeRequest.groovy b/jenkins/L0_MergeRequest.groovy
index e9d45f49daa9..dda93fbfc076 100644
--- a/jenkins/L0_MergeRequest.groovy
+++ b/jenkins/L0_MergeRequest.groovy
@@ -1,6 +1,7 @@
 @Library(['bloom-jenkins-shared-lib@main', 'trtllm-jenkins-shared-lib@main']) _
 
 import java.lang.InterruptedException
+import java.nio.charset.StandardCharsets
 import groovy.transform.Field
 import groovy.json.JsonOutput
 import groovy.json.JsonSlurper
@@ -770,15 +771,23 @@ def getCbtsResult(pipeline, testFilter, globalVars)
             return null
         }
         // Piggyback input JSON on testFilter so each L0_Test stage agent can
-        // re-run main.py and regenerate cbts_test_db/ locally. Capped at
-        // 256 KB; oversize → drop piggyback, Layer 3 falls back to source.
+        // re-run main.py and regenerate cbts_test_db/ locally. The payload is
+        // base64-encoded because the raw JSON contains PR diffs and may include
+        // ${...} or {...} sequences that the Jenkins tokenmacro plugin would
+        // try to evaluate when the parent serializes globalVars for the
+        // Parameterized-Remote-Trigger plugin, raising MacroEvaluationException
+        // and blocking test dispatch. Capped at 256 KB (post-encoding, since
+        // that is what travels on the wire); oversize → drop piggyback,
+        // Layer 3 falls back to source.
         final int CBTS_INPUT_PIGGYBACK_MAX_BYTES = 256000
-        def inputJsonSize = inputJson.length()
-        if (inputJsonSize <= CBTS_INPUT_PIGGYBACK_MAX_BYTES) {
-            result.cbts_input_json = inputJson
-            pipeline.echo("CBTS Layer 3: cbts_input_json piggyback enabled (${inputJsonSize} bytes)")
+        def inputJsonB64 = inputJson.getBytes(StandardCharsets.UTF_8).encodeBase64().toString()
+        def inputJsonB64Size = inputJsonB64.length()
+        if (inputJsonB64Size <= CBTS_INPUT_PIGGYBACK_MAX_BYTES) {
+            result.cbts_input_json_b64 = inputJsonB64
+            pipeline.echo("CBTS Layer 3: cbts_input_json_b64 piggyback enabled " +
+                          "(${inputJsonB64Size} bytes encoded, ${inputJson.length()} bytes raw)")
         } else {
-            pipeline.echo("CBTS Layer 3: cbts_input_json is ${inputJsonSize} bytes, " +
+            pipeline.echo("CBTS Layer 3: cbts_input_json_b64 is ${inputJsonB64Size} bytes, " +
                           "exceeds ${CBTS_INPUT_PIGGYBACK_MAX_BYTES}-byte piggyback limit; " +
                           "downstream stages will fall back to source test-db " +
                           "(Layer 2 stage filtering still applies)")
diff --git a/jenkins/L0_Test.groovy b/jenkins/L0_Test.groovy
index 0751daffcb99..4c8297debbf6 100644
--- a/jenkins/L0_Test.groovy
+++ b/jenkins/L0_Test.groovy
@@ -1,6 +1,7 @@
 @Library(['bloom-jenkins-shared-lib@main', 'trtllm-jenkins-shared-lib@main']) _
 
 import java.lang.InterruptedException
+import java.nio.charset.StandardCharsets
 import groovy.transform.Field
 import groovy.json.JsonOutput
 import com.nvidia.bloom.KubernetesManager
@@ -2456,16 +2457,29 @@ def renderTestDB(pipeline, testContext, llmSrc, stageName, preDefinedMakoOpts=nu
 
     sh "pip3 install --extra-index-url https://urm.nvidia.com/artifactory/api/pypi/sw-tensorrt-pypi/simple --ignore-installed trt-test-db==1.8.5+bc6df7"
     // CBTS Layer 3: regenerate cbts_test_db/ on this stage agent from the
-    // piggybacked input JSON if not already present.
+    // piggybacked input JSON if not already present. The piggyback payload is
+    // base64-encoded on the orchestrator (see getCbtsResult in
+    // L0_MergeRequest.groovy) to keep tokenmacro from interpreting ${...} or
+    // {...} fragments inside the PR diff when globalVars is serialized. If
+    // decoding or regeneration throws (truncated/malformed payload), we
+    // swallow the error: the override directory will be absent below, the
+    // overrideYaml check will fail, and renderTestDB falls back to the
+    // source test-db.
     def cbts = testFilter[(CBTS_RESULT)]
-    if (cbts != null && cbts.test_db_dir_override && cbts.cbts_input_json) {
+    if (cbts != null && cbts.test_db_dir_override && cbts.cbts_input_json_b64) {
         def overrideDir = "${llmSrc}/${cbts.test_db_dir_override}"
         def dirExists = sh(returnStdout: true, script: "test -d ${overrideDir} && echo yes || echo no").trim()
         if (dirExists != "yes") {
-            def cbtsInputLocal = Utils.createTempLocation(pipeline, "./cbts_input.json")
-            pipeline.writeFile(file: cbtsInputLocal, text: cbts.cbts_input_json)
-            sh "apt-get update -qq && apt-get install -y -qq python3-yaml || true"
-            sh "cd ${llmSrc} && python3 jenkins/scripts/cbts/main.py ${cbtsInputLocal} > /dev/null 2>&1 || true"
+            try {
+                def cbtsInputJson = new String(cbts.cbts_input_json_b64.decodeBase64(), StandardCharsets.UTF_8)
+                def cbtsInputLocal = Utils.createTempLocation(pipeline, "./cbts_input.json")
+                pipeline.writeFile(file: cbtsInputLocal, text: cbtsInputJson)
+                sh "apt-get update -qq && apt-get install -y -qq python3-yaml || true"
+                sh "cd ${llmSrc} && python3 jenkins/scripts/cbts/main.py ${cbtsInputLocal} > /dev/null 2>&1 || true"
+            } catch (Exception e) {
+                echo "CBTS Layer 3: failed to materialize piggyback payload " +
+                     "(${e.class.simpleName}: ${e.message}); falling back to source test-db"
+            }
         }
     }
     def testDBPath = "${llmSrc}/tests/integration/test_lists/test-db"
diff --git a/jenkins/scripts/cbts/README.md b/jenkins/scripts/cbts/README.md
index aa445265f9d1..9dbb1cdc5f36 100644
--- a/jenkins/scripts/cbts/README.md
+++ b/jenkins/scripts/cbts/README.md
@@ -197,13 +197,19 @@ Decision JSON:
 `cbts_test_db/` is written on the L0_MergeRequest agent and is not
 available to downstream `L0_Test-*` pods. To regenerate it per stage:
 
-1. `getCbtsResult` stores the input JSON in `result.cbts_input_json`,
-   which rides along inside `testFilter`.
-2. `renderTestDB` on the stage agent writes it to a temp file and re-runs
-   `main.py`. Output is deterministic, so each agent gets the same
-   `cbts_test_db/` as L0_MergeRequest produced.
-
-If `cbts_input_json` exceeds 256 KB the piggyback is dropped; Layer 3 falls
+1. `getCbtsResult` base64-encodes the input JSON and stores it in
+   `result.cbts_input_json_b64`, which rides along inside `testFilter`.
+   Encoding is mandatory: the raw payload contains PR diff text which can
+   include `${...}` or `{...}` fragments (Python f-strings, shell vars, etc.)
+   that the Jenkins tokenmacro plugin tries to evaluate when the parent
+   serializes `globalVars` for `Parameterized-Remote-Trigger`, raising
+   `MacroEvaluationException` and blocking test dispatch.
+2. `renderTestDB` on the stage agent decodes `cbts_input_json_b64`, writes
+   it to a temp file, and re-runs `main.py`. Output is deterministic, so
+   each agent gets the same `cbts_test_db/` as L0_MergeRequest produced.
+
+If `cbts_input_json_b64` exceeds 256 KB (post-encoding, the size that
+actually travels over the wire) the piggyback is dropped; Layer 3 falls
 back to the source test-db on each stage agent. Layer 2 still applies.
 
 ## Split-collapse heuristic (Layer 2.5)
@@ -279,7 +285,7 @@ CBTS defers to the existing filter chain when:
   YAML edit)
 - Combined scope is `None` (incompatible mix)
 - Layer 3 narrowing would empty a block — block keeps original tests
-- `cbts_input_json` exceeds 256 KB — Layer 3 falls back per stage
+- `cbts_input_json_b64` (post-encoding) exceeds 256 KB — Layer 3 falls back per stage
 - Narrowed YAML missing/empty on a stage agent — renderTestDB falls back
 
 Every fallback emits an `echo` log line.