diff --git a/apps/obsidian/src/utils/__tests__/validateNodeType.test.ts b/apps/obsidian/src/utils/__tests__/validateNodeType.test.ts
index e85e90334..5c1e9f714 100644
--- a/apps/obsidian/src/utils/__tests__/validateNodeType.test.ts
+++ b/apps/obsidian/src/utils/__tests__/validateNodeType.test.ts
@@ -1,8 +1,10 @@
 import { describe, expect, it } from "vitest";
 import { decorateTitle } from "@repo/database/lib/decorateTitle";
+import type { DiscourseNode } from "~/types";
 import {
   checkInvalidChars,
   normalizeImportedNodeFormat,
+  validateNodeFormat,
 } from "~/utils/validateNodeType";
 
 describe("normalizeImportedNodeFormat", () => {
@@ -55,3 +57,49 @@ describe("normalizeImportedNodeFormat", () => {
     expect(normalizeImportedNodeFormat(format)).toBe(format);
   });
 });
+
+describe("validateNodeFormat", () => {
+  const currentNode: DiscourseNode = {
+    id: "node-1",
+    name: "Evidence",
+    format: "",
+    created: 0,
+    modified: 0,
+  };
+  const validate = (format: string): ReturnType<typeof validateNodeFormat> =>
+    validateNodeFormat({ format, currentNode, allNodes: [currentNode] });
+
+  it.each([
+    [
+      "EVD - {content} - {Source}",
+      "Format contains unsupported placeholder: {Source}. Only {content} is supported.",
+    ],
+    [
+      "{Author}: {content}",
+      "Format contains unsupported placeholder: {Author}. Only {content} is supported.",
+    ],
+    [
+      "{Source} - {content} - {Author} - {Source}",
+      "Format contains unsupported placeholders: {Source}, {Author}. Only {content} is supported.",
+    ],
+  ])("rejects the unsupported placeholders in %s", (format, error) => {
+    expect(validate(format)).toEqual({ isValid: false, error });
+  });
+
+  it.each(["CLM - {content}", "{content}", "@{content}"])(
+    "accepts the content-only format %s",
+    (format) => {
+      expect(validate(format)).toEqual({ isValid: true });
+    },
+  );
+
+  it.each(["CLM - title", "EVD - {Source}"])(
+    "reports the missing {content} for %s",
+    (format) => {
+      expect(validate(format)).toEqual({
+        isValid: false,
+        error: 'Format must include the placeholder "{content}"',
+      });
+    },
+  );
+});
diff --git a/apps/obsidian/src/utils/validateNodeFormat.ts b/apps/obsidian/src/utils/validateNodeFormat.ts
deleted file mode 100644
index 5e03281b8..000000000
--- a/apps/obsidian/src/utils/validateNodeFormat.ts
+++ /dev/null
@@ -1,30 +0,0 @@
-export const validateNodeFormat = (
-  format: string,
-): {
-  isValid: boolean;
-  error?: string;
-} => {
-  if (!format) {
-    return {
-      isValid: false,
-      error: "Format cannot be empty",
-    };
-  }
-
-  if (format.includes("[[") || format.includes("]]")) {
-    return {
-      isValid: false,
-      error: "Format should not contain double brackets [[ or ]]",
-    };
-  }
-
-  const hasVariable = /{[a-zA-Z]+}/.test(format);
-  if (!hasVariable) {
-    return {
-      isValid: false,
-      error: "Format must contain at least one variable in {varName} format",
-    };
-  }
-
-  return { isValid: true };
-};
diff --git a/apps/obsidian/src/utils/validateNodeType.ts b/apps/obsidian/src/utils/validateNodeType.ts
index f577e7125..da98c8a32 100644
--- a/apps/obsidian/src/utils/validateNodeType.ts
+++ b/apps/obsidian/src/utils/validateNodeType.ts
@@ -1,3 +1,7 @@
+import {
+  CONTENT_PLACEHOLDER,
+  FORMAT_PLACEHOLDER,
+} from "@repo/database/lib/decorateTitle";
 import { DiscourseNode } from "~/types";
 
 type ValidationResult = {
@@ -35,6 +39,21 @@ export const validateNodeFormat = ({
     };
   }
 
+  // Same placeholder rule as decorateTitle, which can't build titles from other placeholders.
+  const unsupportedPlaceholders = [
+    ...new Set(
+      (format.match(FORMAT_PLACEHOLDER) ?? []).filter(
+        (placeholder) => placeholder.toLowerCase() !== CONTENT_PLACEHOLDER,
+      ),
+    ),
+  ];
+  if (unsupportedPlaceholders.length > 0) {
+    return {
+      isValid: false,
+      error: `Format contains unsupported placeholder${unsupportedPlaceholders.length > 1 ? "s" : ""}: ${unsupportedPlaceholders.join(", ")}. Only ${CONTENT_PLACEHOLDER} is supported.`,
+    };
+  }
+
   const invalidCharsResult = checkInvalidChars(format);
   if (!invalidCharsResult.isValid) {
     return invalidCharsResult;