diff --git a/scripts/check-terraform-isolation.mjs b/scripts/check-terraform-isolation.mjs
index d289f9a7..484b6a50 100644
--- a/scripts/check-terraform-isolation.mjs
+++ b/scripts/check-terraform-isolation.mjs
@@ -33,6 +33,13 @@ export function isTerraformPath(file) {
   return file.startsWith("terraform/");
 }
 
+// Markdown under terraform/ does not queue an HCP VCS run (workspace triggers
+// are terraform/live/dev/** and terraform/live/modules/**), so it is not a
+// Terraform change for the mixed-PR check.
+export function isTerraformInfrastructurePath(file) {
+  return isTerraformPath(file) && !file.endsWith(".md");
+}
+
 export function mayAccompanyTerraform(file) {
   if (isTerraformPath(file)) return true;
   if (file.endsWith(".md")) return true;
@@ -47,7 +54,7 @@ export function mayAccompanyTerraform(file) {
  */
 export function classifyChangedFiles(files) {
   const unique = [...new Set(files.map((file) => file.trim()).filter(Boolean))].sort();
-  const terraform = unique.filter(isTerraformPath);
+  const terraform = unique.filter(isTerraformInfrastructurePath);
   const application = unique.filter((file) => !mayAccompanyTerraform(file));
   return {
     terraform,
diff --git a/scripts/check-terraform-isolation.test.mjs b/scripts/check-terraform-isolation.test.mjs
index 7fdac71b..8d3fa662 100644
--- a/scripts/check-terraform-isolation.test.mjs
+++ b/scripts/check-terraform-isolation.test.mjs
@@ -8,6 +8,7 @@ import { fileURLToPath } from "node:url";
 import {
   OVERRIDE_LABEL,
   classifyChangedFiles,
+  isTerraformInfrastructurePath,
   mayAccompanyTerraform,
 } from "./check-terraform-isolation.mjs";
 
@@ -72,6 +73,18 @@ test("terraform-only and application-only changes are not mixed", () => {
   assert.equal(classifyChangedFiles([]).mixed, false);
 });
 
+test("terraform documentation does not mix with application or workflow changes", () => {
+  assert.equal(isTerraformInfrastructurePath("terraform/README.md"), false);
+  assert.equal(isTerraformInfrastructurePath("terraform/live/dev/main.tf"), true);
+  assert.equal(
+    classifyChangedFiles(["terraform/README.md", ".github/workflows/ci.yaml"]).mixed,
+    false,
+  );
+  const docsOnly = runGate(["terraform/README.md", ".github/workflows/ci.yaml"]);
+  assert.equal(docsOnly.status, 0, docsOnly.stdout + docsOnly.stderr);
+  assert.match(docsOnly.stdout, /PASS/);
+});
+
 test("terraform plus application is mixed and lists the offending files", () => {
   const result = classifyChangedFiles([
     "terraform/live/dev/main.tf",
@@ -115,11 +128,7 @@ test("removing the override fails a mixed change that was previously green", ()
   const previouslyGreen = runGate(files, {
     TERRAFORM_ISOLATION_OVERRIDE: "true",
   });
-  assert.equal(
-    previouslyGreen.status,
-    0,
-    previouslyGreen.stdout + previouslyGreen.stderr,
-  );
+  assert.equal(previouslyGreen.status, 0, previouslyGreen.stdout + previouslyGreen.stderr);
   assert.match(previouslyGreen.stdout, /WARNING/);
 
   // CI sets TERRAFORM_ISOLATION_OVERRIDE from contains(...labels), which is
@@ -128,11 +137,7 @@ test("removing the override fails a mixed change that was previously green", ()
   const afterLabelRemoved = runGate(files, {
     TERRAFORM_ISOLATION_OVERRIDE: "false",
   });
-  assert.equal(
-    afterLabelRemoved.status,
-    1,
-    afterLabelRemoved.stdout + afterLabelRemoved.stderr,
-  );
+  assert.equal(afterLabelRemoved.status, 1, afterLabelRemoved.stdout + afterLabelRemoved.stderr);
   assert.match(afterLabelRemoved.stdout, /FAIL/);
   assert.match(afterLabelRemoved.stdout, /deploy\.yml/);
 });
diff --git a/terraform/README.md b/terraform/README.md
index 8522c080..b1814740 100644
--- a/terraform/README.md
+++ b/terraform/README.md
@@ -226,7 +226,9 @@ the labels. Push-to-`dev` releases return behind the repository variable
   labels currently on the PR; the other CI jobs skip on those events so a
   label change does not re-run the suite. Removing the label fails a mixed
   PR that had previously passed with the override, so a stale green check
-  cannot merge. The label is the approval record. The override is temporary:
+  cannot merge. Markdown under `terraform/` does not count as a Terraform
+  change for this gate; it does not match the workspace trigger patterns.
+  The label is the approval record. The override is temporary:
   a follow-up PR after PR C removes the label path from the checker and
   workflow so the gate has no exception.
 - **Every Terraform merge produces a VCS run.** A human confirms or discards