diff --git a/addons/api/app/mirage/factories/role.js b/addons/api/app/mirage/factories/role.js
index dbfded391..b394504c9 100644
--- a/addons/api/app/mirage/factories/role.js
+++ b/addons/api/app/mirage/factories/role.js
@@ -26,7 +26,7 @@ export default factory.extend({
       'set-grant-scopes',
     ],
   grant_strings: () => [
-    'ids=*;action=*',
+    'ids=*;actions=*',
     'ids=*;type=host-catalog;actions=create,read',
   ],
 
diff --git a/addons/core/translations/resources/en-us.yaml b/addons/core/translations/resources/en-us.yaml
index ad2dae9f9..ba64409a5 100644
--- a/addons/core/translations/resources/en-us.yaml
+++ b/addons/core/translations/resources/en-us.yaml
@@ -670,6 +670,51 @@ role:
       wildcard-actions: Wildcard - matches all actions
       template-value: Template value
       all-fields: All fields
+    linting-errors:
+      general:
+        whitespace-not-allowed: Whitespace is not allowed
+        leading-semicolon-not-allowed: Leading semicolon is not allowed
+        trailing-semicolon-not-allowed: Trailing semicolon is not allowed
+        invalid-character: Invalid character "{character}"
+        invalid-format: 'Invalid format: expected key=value'
+        invalid-syntax: Invalid syntax
+      fields:
+        duplicate-field: Duplicate field "{field}"
+        unknown-field: Unknown field "{field}"
+        empty-value: '"{field}" value cannot be empty'
+        missing-ids-or-type: Missing "ids" or "type" fields
+        missing-actions: Missing "actions" field
+        missing-actions-or-output-fields: Missing "actions" or "output_fields" fields
+      type:
+        invalid-type: Invalid resource type "{type}"
+        not-top-level: Type "{type}" is not a top-level type
+        not-child-type: Type "{type}" is not a child type of the pinned ID
+        missing-for-wildcard-ids: Missing "type" field for wildcard ids
+        wildcard-requires-ids: Missing "ids" field for wildcard type
+      ids:
+        empty-list: '"ids" field does not contain at least one id'
+        wildcard-cannot-combine: Wildcard id "*" cannot be combined with other ids
+        duplicate-template: Duplicate id "{primary}" and "{secondary}"
+        duplicate-id: Duplicate id "{id}"
+        unknown-template: Unknown template "{id}"
+        invalid-id: Invalid id "{id}"
+        mismatched-types: Ids do not have the same type. Invalid id "{id}"
+        must-support-child-types: Pinned IDs must support child types. Invalid id "{id}"
+        must-match-parent-type: Pinned IDs must be "{parentType}" ids. Invalid id "{id}"
+      actions:
+        empty-list: '"actions" field does not contain at least one action'
+        wildcard-cannot-combine: Wildcard action "*" cannot be combined with other actions
+        duplicate-action: Duplicate action "{action}"
+        invalid-action: Invalid action "{action}"
+        id-only: Only id actions for "{type}" type are allowed. Invalid action "{action}"
+        collection-only: Only collection actions are allowed. Invalid action "{action}"
+        noop-requires-list: '"no-op" action should only be used with "list" action'
+        list-requires-noop: '"list" action should be used with "no-op" action to have an effect'
+        noop-unnecessary: '"no-op" action is unnecessary when other actions are specified'
+      editor:
+        remove: Remove
+        remove-comma: Remove comma
+        add-noop: Add "no-op" action
     editor:
       title: Grant Editor
       description: Add each new grant string on a different line
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 5e445a1b2..30433bc3b 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -8728,8 +8728,8 @@ packages:
     resolution: {integrity: sha512-yYrrsWnrXMcdsnu/7YMYAofM1ktpL5By7vZhf15CrXijWWrEYZks5AXBudalfSWJLlnen/QUJUB5aoB0kqZUGA==}
     engines: {node: '>=6.0.0'}
 
-  terser-webpack-plugin@5.3.17:
-    resolution: {integrity: sha512-YR7PtUp6GMU91BgSJmlaX/rS2lGDbAF7D+Wtq7hRO+MiljNmodYvqslzCFiYVAgW+Qoaaia/QUIP4lGXufjdZw==}
+  terser-webpack-plugin@5.4.0:
+    resolution: {integrity: sha512-Bn5vxm48flOIfkdl5CaD2+1CiUVbonWQ3KQPyP7/EuIl9Gbzq/gQFOzaMFUEgVjB1396tcK0SG8XcNJ/2kDH8g==}
     engines: {node: '>= 10.13.0'}
     peerDependencies:
       '@swc/core': '*'
@@ -18918,7 +18918,7 @@ snapshots:
       mkdirp: 0.5.6
       rimraf: 2.6.3
 
-  terser-webpack-plugin@5.3.17(esbuild@0.25.9)(webpack@5.105.4(esbuild@0.25.9)):
+  terser-webpack-plugin@5.4.0(esbuild@0.25.9)(webpack@5.105.4(esbuild@0.25.9)):
     dependencies:
       '@jridgewell/trace-mapping': 0.3.31
       jest-worker: 27.5.1
@@ -19465,7 +19465,7 @@ snapshots:
       neo-async: 2.6.2
       schema-utils: 4.3.3
       tapable: 2.3.0
-      terser-webpack-plugin: 5.3.17(esbuild@0.25.9)(webpack@5.105.4(esbuild@0.25.9))
+      terser-webpack-plugin: 5.4.0(esbuild@0.25.9)(webpack@5.105.4(esbuild@0.25.9))
       watchpack: 2.5.1
       webpack-sources: 3.3.4
     transitivePeerDependencies:
diff --git a/ui/admin/app/components/form/role/edit-grants/index.js b/ui/admin/app/components/form/role/edit-grants/index.js
index e24f290cf..1acefebea 100644
--- a/ui/admin/app/components/form/role/edit-grants/index.js
+++ b/ui/admin/app/components/form/role/edit-grants/index.js
@@ -11,9 +11,12 @@ import {
   autocompletion,
   completionKeymap,
   keymap,
+  linter,
+  lintGutter,
+  lintKeymap,
 } from '@hashicorp/design-system-components/codemirror';
-
 import { createGrantCompletionSource } from 'admin/utils/grant-completions';
+import { createGrantLinter } from 'admin/utils/grant-linter';
 
 export default class FormRoleEditGrantsComponent extends Component {
   @service intl;
@@ -41,10 +44,17 @@ export default class FormRoleEditGrantsComponent extends Component {
     ),
   };
 
+  translateLintingError = (key, options = {}) =>
+    this.intl.t(`resources.role.edit-grants.linting-errors.${key}`, options);
+
   completionSource = createGrantCompletionSource(
     this.args.grantsSchema,
     this.completionTranslatedStrings,
   );
+  linterSource = createGrantLinter(
+    this.args.grantsSchema,
+    this.translateLintingError,
+  );
 
   @tracked grantStringsText = (this.args.model?.grant_strings ?? []).join('\n');
   @tracked currentLineText = this.args.model?.grant_strings?.[0] ?? '';
@@ -57,7 +67,9 @@ export default class FormRoleEditGrantsComponent extends Component {
       // Trigger autocompletion when the user completes a grant field (which we labeled as keywords)
       activateOnCompletion: (completion) => completion.type === 'keyword',
     }),
-    keymap.of(completionKeymap),
+    linter(this.linterSource),
+    lintGutter(),
+    keymap.of([...completionKeymap, ...lintKeymap]),
   ];
 
   get grantStrings() {
diff --git a/ui/admin/app/utils/grant-linter.js b/ui/admin/app/utils/grant-linter.js
new file mode 100644
index 000000000..a126248d6
--- /dev/null
+++ b/ui/admin/app/utils/grant-linter.js
@@ -0,0 +1,767 @@
+/**
+ * Copyright IBM Corp. 2021, 2026
+ * SPDX-License-Identifier: BUSL-1.1
+ */
+
+const GRANT_FIELDS = ['ids', 'type', 'actions', 'output_fields'];
+const ID_TEMPLATES = [
+  '{{.Account.Id}}',
+  '{{.User.Id}}',
+  '{{user.id}}',
+  '{{account.id}}',
+];
+
+const createDeleteTextAction = (name) => ({
+  name,
+  apply(view, from, to) {
+    view.dispatch({
+      changes: { from, to },
+    });
+  },
+});
+
+const createAddTextAction = (name) => ({
+  name,
+  apply(view, from) {
+    view.dispatch({
+      changes: { from, insert: 'no-op,' },
+    });
+  },
+});
+
+const normalizeGrantsSchema = (grantsSchema) => {
+  const resourceTypes = grantsSchema.resource_types ?? [];
+
+  const resourcesByType = resourceTypes.reduce((resources, resourceType) => {
+    const collectionActions = resourceType.collection_actions ?? [];
+    const idActions = resourceType.id_actions ?? [];
+    const idPrefixes = resourceType.id_prefixes ?? [];
+
+    resources[resourceType.type] = {
+      actions: [...collectionActions, ...idActions],
+      collectionActions,
+      idActions,
+      idPrefixes,
+      parentType: resourceType.parent_type,
+    };
+
+    return resources;
+  }, {});
+
+  const validResourceTypes = resourceTypes.map((resource) => resource.type);
+  validResourceTypes.push('*');
+
+  const allActions = new Set();
+  Object.values(resourcesByType).forEach((resource) => {
+    resource.actions.forEach((action) => allActions.add(action));
+  });
+  const validActions = Array.from(allActions);
+  validActions.push('*');
+  validActions.push('no-op');
+
+  const resourcesByPrefix = resourceTypes.reduce((map, resource) => {
+    resource.id_prefixes?.forEach((prefix) => {
+      map[prefix] = resource.type;
+    });
+    return map;
+  }, {});
+
+  let parentTypes = new Set(
+    resourceTypes.filter((r) => r.parent_type).map((r) => r.parent_type),
+  );
+  parentTypes = Array.from(parentTypes);
+
+  const topLevelTypes = resourceTypes
+    .filter((r) => {
+      const hasCreateAction = r.collection_actions.includes('create');
+      const hasListAction = r.collection_actions.includes('list');
+      return !r.parent_type && (hasCreateAction || hasListAction);
+    })
+    .map((r) => r.type);
+
+  const childResourceTypesByParentType = resourceTypes.reduce(
+    (childrenByParentType, resourceType) => {
+      const parentType = resourceType.parent_type;
+
+      if (!parentType) {
+        return childrenByParentType;
+      }
+
+      childrenByParentType[parentType] = [
+        ...(childrenByParentType[parentType] ?? []),
+        resourceType.type,
+      ];
+
+      return childrenByParentType;
+    },
+    {},
+  );
+
+  return {
+    resourcesByType,
+    validResourceTypes,
+    validActions,
+    resourcesByPrefix,
+    childResourceTypesByParentType,
+    parentTypes,
+    topLevelTypes,
+  };
+};
+
+const grantLinter = (context, schema, translate) => {
+  const diagnostics = [];
+  const doc = context.state.doc.toString();
+  const lines = doc.split('\n');
+
+  let currentPos = 0;
+
+  lines.forEach((line) => {
+    const trimmedLine = line.trim();
+    const lineStart = currentPos;
+    const lineEnd = currentPos + line.length;
+
+    // Check for whitespace
+    const whitespaceMatches = line.matchAll(/\s+/g);
+    for (const match of whitespaceMatches) {
+      const spaceStart = lineStart + match.index;
+      const spaceEnd = spaceStart + match[0].length;
+      diagnostics.push({
+        from: spaceStart,
+        to: spaceEnd,
+        severity: 'error',
+        message: translate('general.whitespace-not-allowed'),
+        actions: [createDeleteTextAction(translate('editor.remove'))],
+      });
+    }
+
+    const trimStart = line.indexOf(trimmedLine);
+    // Check for leading semicolon
+    if (trimmedLine.startsWith(';')) {
+      diagnostics.push({
+        from: lineStart,
+        to: lineStart + trimStart + 1,
+        severity: 'error',
+        message: translate('general.leading-semicolon-not-allowed'),
+        actions: [createDeleteTextAction(translate('editor.remove'))],
+      });
+    }
+
+    // Check for trailing semicolon
+    if (trimmedLine.endsWith(';')) {
+      const semicolonPos = lineStart + line.lastIndexOf(';');
+      diagnostics.push({
+        from: semicolonPos,
+        to: semicolonPos + 1,
+        severity: 'error',
+        message: translate('general.trailing-semicolon-not-allowed'),
+        actions: [createDeleteTextAction(translate('editor.remove'))],
+      });
+    }
+
+    // Check for invalid characters (only allow alphanumeric characters, equal signs, commas, semicolons, underscores, hyphens, curly braces, and periods)
+    const invalidCharMatch = line.match(/[^a-zA-Z0-9=,;:_*\-.{}\s]/g) || [];
+    for (const invalidChar of invalidCharMatch) {
+      const invalidCharIndex = lineStart + line.indexOf(invalidChar);
+      diagnostics.push({
+        from: invalidCharIndex,
+        to: invalidCharIndex + 1,
+        severity: 'error',
+        message: translate('general.invalid-character', {
+          character: invalidChar,
+        }),
+        actions: [createDeleteTextAction(translate('editor.remove'))],
+      });
+    }
+
+    // Parse key-value pairs separated by semicolons
+    const pairs = trimmedLine.split(';').filter((p) => p.trim());
+    const parsedFields = {};
+    const fieldPositions = {};
+    const allFields = [];
+    const fieldKeyCount = {};
+
+    let pairOffset = trimStart; // Start from where trimmed content begins
+
+    for (const pair of pairs) {
+      const pairInLine = line.indexOf(pair, pairOffset - trimStart);
+      const [key, ...valueParts] = pair.split('=');
+      const value = valueParts.join('='); // Handle cases where value contains '='
+
+      if (!key || value === undefined) {
+        // Invalid format - not a key=value pair
+        const pairStart = lineStart + pairInLine;
+        diagnostics.push({
+          from: pairStart,
+          to: pairStart + pair.length,
+          severity: 'error',
+          message: translate('general.invalid-format'),
+        });
+        continue;
+      }
+
+      const trimmedKey = key.trim();
+      const keyStartInPair = pair.indexOf(trimmedKey);
+      const valueStartInPair = pair.indexOf('=') + 1;
+
+      const pos = {
+        keyStart: lineStart + pairInLine + keyStartInPair,
+        valueStart: lineStart + pairInLine + valueStartInPair,
+        valueEnd: lineStart + pairInLine + pair.length,
+      };
+      allFields.push({ key: trimmedKey, value: value.trim(), pos });
+      fieldKeyCount[trimmedKey] = (fieldKeyCount[trimmedKey] ?? 0) + 1;
+
+      pairOffset = pairInLine + pair.length + 1; // +1 for semicolon
+    }
+
+    // Validate there are no duplicate fields and store the last instance of each field for further validation
+    for (const field of allFields) {
+      parsedFields[field.key] = field.value;
+      fieldPositions[field.key] = field.pos;
+      if (fieldKeyCount[field.key] > 1) {
+        diagnostics.push({
+          from: field.pos.keyStart,
+          to: field.pos.valueEnd,
+          severity: 'error',
+          message: translate('fields.duplicate-field', {
+            field: field.key,
+          }),
+        });
+      }
+    }
+
+    // Validate all fields are recognized
+    for (const field of Object.keys(parsedFields)) {
+      if (!GRANT_FIELDS.includes(field)) {
+        const pos = fieldPositions[field];
+        diagnostics.push({
+          from: pos.keyStart,
+          to: pos.valueEnd,
+          severity: 'error',
+          message: translate('fields.unknown-field', { field }),
+        });
+      }
+    }
+
+    // Validate field values are not empty
+    for (const [field, value] of Object.entries(parsedFields)) {
+      if (!value.trim()) {
+        const pos = fieldPositions[field];
+        diagnostics.push({
+          from: pos.valueStart,
+          to: pos.valueEnd,
+          severity: 'error',
+          message: translate('fields.empty-value', { field }),
+        });
+      }
+    }
+
+    const validatedFields = {};
+
+    // Validate type field value is a valid resource type
+    if (parsedFields.type) {
+      validatedFields.type = { value: '', wildcard: false };
+      const typeValue = parsedFields.type.trim();
+      const pos = fieldPositions.type;
+      if (!schema.validResourceTypes.includes(typeValue)) {
+        diagnostics.push({
+          from: pos.valueStart,
+          to: pos.valueEnd,
+          severity: 'error',
+          message: translate('type.invalid-type', { type: typeValue }),
+        });
+      } else {
+        validatedFields.type.value = typeValue;
+        if (!parsedFields.ids) {
+          if (!schema.topLevelTypes.includes(typeValue)) {
+            diagnostics.push({
+              from: pos.valueStart,
+              to: pos.valueEnd,
+              severity: 'error',
+              message: translate('type.not-top-level', {
+                type: typeValue,
+              }),
+            });
+          }
+        }
+      }
+      validatedFields.type.wildcard = typeValue === '*';
+    }
+
+    // Validate ids field
+    if (parsedFields.ids) {
+      validatedFields.ids = { value: [], knownType: '', wildcard: false };
+      const pos = fieldPositions.ids;
+      const idsList = validateListField(
+        parsedFields.ids,
+        pos,
+        diagnostics,
+        translate,
+      );
+      if (idsList.length === 0) {
+        diagnostics.push({
+          from: pos.valueStart,
+          to: pos.valueEnd,
+          severity: 'error',
+          message: translate('ids.empty-list'),
+        });
+      } else if (idsList.includes('*')) {
+        if (idsList.length > 1) {
+          const wildCardIndex = pos.valueStart + parsedFields.ids.indexOf('*');
+          diagnostics.push({
+            from: wildCardIndex,
+            to: wildCardIndex + 1, // Include wildcard and comma after it
+            severity: 'error',
+            message: translate('ids.wildcard-cannot-combine'),
+          });
+        } else {
+          validatedFields.ids.wildcard = true;
+          if (!parsedFields.type) {
+            diagnostics.push({
+              from: lineStart,
+              to: lineEnd,
+              severity: 'error',
+              message: translate('type.missing-for-wildcard-ids'),
+            });
+          }
+        }
+      } else {
+        const validIdType = validateIdsField(
+          schema,
+          diagnostics,
+          idsList,
+          validatedFields.type,
+          pos,
+          fieldPositions.type,
+          translate,
+        );
+        if (validIdType) {
+          validatedFields.ids.knownType = validIdType;
+        }
+      }
+    }
+
+    if (!validatedFields.ids) {
+      if (!validatedFields.type) {
+        diagnostics.push({
+          from: lineStart,
+          to: lineEnd,
+          severity: 'error',
+          message: translate('fields.missing-ids-or-type'),
+        });
+      } else if (validatedFields.type.wildcard) {
+        diagnostics.push({
+          from: lineStart,
+          to: lineEnd,
+          severity: 'error',
+          message: translate('type.wildcard-requires-ids'),
+        });
+      } else {
+        if (!parsedFields.actions && !parsedFields.output_fields) {
+          diagnostics.push({
+            from: lineStart,
+            to: lineEnd,
+            severity: 'error',
+            message: translate('fields.missing-actions-or-output-fields'),
+          });
+        }
+      }
+    } else {
+      if (!parsedFields.actions && !parsedFields.output_fields) {
+        diagnostics.push({
+          from: lineStart,
+          to: lineEnd,
+          severity: 'error',
+          message: translate('fields.missing-actions'),
+        });
+      }
+    }
+
+    // Validate actions field
+    if (parsedFields.actions) {
+      const pos = fieldPositions.actions;
+      const actionList = validateListField(
+        parsedFields.actions,
+        pos,
+        diagnostics,
+        translate,
+      );
+      if (actionList.length === 0) {
+        diagnostics.push({
+          from: pos.valueStart,
+          to: pos.valueEnd,
+          severity: 'error',
+          message: translate('actions.empty-list'),
+        });
+      } else if (actionList.includes('*') && actionList.length > 1) {
+        const wildcardIndex =
+          pos.valueStart + parsedFields.actions.indexOf('*');
+        diagnostics.push({
+          from: wildcardIndex,
+          to: wildcardIndex + 1,
+          severity: 'error',
+          message: translate('actions.wildcard-cannot-combine'),
+          actions: [createDeleteTextAction(translate('editor.remove'))],
+        });
+      } else {
+        // Validate individual actions against the resource type
+        validateActionsField(
+          schema,
+          diagnostics,
+          actionList,
+          validatedFields,
+          pos,
+          translate,
+        );
+      }
+    }
+    currentPos += line.length + 1; // +1 for newline
+  });
+
+  return diagnostics;
+};
+
+const validateListField = (fieldValue, pos, diagnostics, translate) => {
+  const unfilteredVals = fieldValue.split(',');
+  const valList = [];
+  let segmentStart = 0;
+  const maxIndex = unfilteredVals.length - 1;
+  for (const [index, val] of unfilteredVals.entries()) {
+    const emptyVal = val.match(/^\s*$/);
+    if (!emptyVal) {
+      valList.push(val);
+    }
+    if (index < maxIndex) {
+      const emptyNextVal = unfilteredVals[index + 1].match(/^\s*$/);
+      if (emptyVal || emptyNextVal) {
+        const commaPos = segmentStart + val.length;
+        diagnostics.push({
+          from: pos.valueStart + commaPos,
+          to: pos.valueStart + commaPos + 1, // +1 for comma
+          severity: 'error',
+          message: translate('general.invalid-syntax'),
+          actions: [createDeleteTextAction(translate('editor.remove-comma'))],
+        });
+      }
+    }
+    segmentStart += val.length + 1; // +1 for comma delimiter
+  }
+
+  return valList;
+};
+
+// Returns template, resource type, or null;
+const idType = (schema, id) => {
+  if (id.startsWith('{{') && id.endsWith('}}')) {
+    return 'template';
+  }
+  const prefix = id.split('_')[0];
+  return schema.resourcesByPrefix[prefix];
+};
+
+const getChildResourceActions = (schema, parentType) => {
+  if (
+    !parentType ||
+    !schema.childResourceTypesByParentType[parentType]?.length
+  ) {
+    return [];
+  }
+
+  const childTypes = schema.childResourceTypesByParentType[parentType] ?? [];
+
+  return [
+    ...new Set(
+      childTypes.flatMap((type) => schema.resourcesByType[type]?.actions ?? []),
+    ),
+  ];
+};
+
+const validateIdsField = (
+  schema,
+  diagnostics,
+  idsList,
+  validatedFieldsType = {},
+  idsPos,
+  typePos,
+  translate,
+) => {
+  if (
+    idsList.includes('{{.Account.Id}}') &&
+    idsList.includes('{{account.id}}')
+  ) {
+    diagnostics.push({
+      from: idsPos.valueStart,
+      to: idsPos.valueEnd,
+      severity: 'error',
+      message: translate('ids.duplicate-template', {
+        primary: '{{.Account.Id}}',
+        secondary: '{{account.id}}',
+      }),
+    });
+    return;
+  }
+  if (idsList.includes('{{.User.Id}}') && idsList.includes('{{user.id}}')) {
+    diagnostics.push({
+      from: idsPos.valueStart,
+      to: idsPos.valueEnd,
+      severity: 'error',
+      message: translate('ids.duplicate-template', {
+        primary: '{{.User.Id}}',
+        secondary: '{{user.id}}',
+      }),
+    });
+    return;
+  }
+  let segmentStart = idsPos.valueStart;
+  let seenIdType;
+  for (const [i, id] of idsList.entries()) {
+    let segmentEnd = segmentStart + id.length;
+    if (i === 0) {
+      seenIdType = idType(schema, id);
+    }
+    if (i < idsList.length - 1) {
+      segmentEnd += 1; // Include comma delimiter for all but last id
+    }
+    if (idsList.slice(i + 1).includes(id)) {
+      diagnostics.push({
+        from: segmentStart,
+        to: segmentEnd,
+        severity: 'error',
+        message: translate('ids.duplicate-id', { id }),
+        actions: [createDeleteTextAction(translate('editor.remove'))],
+      });
+      return;
+    }
+    const currentIdType = idType(schema, id);
+    if (currentIdType === 'template') {
+      if (!ID_TEMPLATES.includes(id)) {
+        diagnostics.push({
+          from: segmentStart,
+          to: segmentEnd,
+          severity: 'error',
+          message: translate('ids.unknown-template', { id }),
+        });
+        return;
+      }
+    } else {
+      if (!currentIdType) {
+        diagnostics.push({
+          from: segmentStart,
+          to: segmentEnd,
+          severity: 'error',
+          message: translate('ids.invalid-id', { id }),
+        });
+        return;
+      }
+    }
+    if (currentIdType !== seenIdType) {
+      diagnostics.push({
+        from: idsPos.valueStart,
+        to: idsPos.valueEnd,
+        severity: 'error',
+        message: translate('ids.mismatched-types', { id }),
+      });
+      return;
+    }
+    if (validatedFieldsType.wildcard) {
+      // If type is wildcard, then pinned id(s) must support child types
+      if (!schema.parentTypes.includes(currentIdType)) {
+        diagnostics.push({
+          from: idsPos.valueStart,
+          to: idsPos.valueEnd,
+          severity: 'error',
+          message: translate('ids.must-support-child-types', { id }),
+        });
+        return;
+      }
+    } else if (validatedFieldsType.value) {
+      // If type is known and not wildcard, then pinned id(s) must match the type
+      const parentType =
+        schema.resourcesByType[validatedFieldsType.value]?.parentType;
+      if (!parentType) {
+        diagnostics.push({
+          from: typePos.valueStart,
+          to: typePos.valueEnd,
+          severity: 'error',
+          message: translate('type.not-child-type', {
+            type: validatedFieldsType.value,
+          }),
+        });
+        return;
+      }
+      if (currentIdType !== parentType) {
+        diagnostics.push({
+          from: idsPos.valueStart,
+          to: idsPos.valueEnd,
+          severity: 'error',
+          message: translate('ids.must-match-parent-type', {
+            id,
+            parentType,
+          }),
+        });
+        return;
+      }
+    }
+    segmentStart += id.length + 1; // +1 for comma
+  }
+  if (seenIdType === 'template') {
+    if (idsList.length > 1) {
+      seenIdType = 'template-multiple';
+    } else if (
+      idsList[0] === '{{.Account.Id}}' ||
+      idsList[0] === '{{account.id}}'
+    ) {
+      seenIdType = 'account-template';
+    } else if (idsList[0] === '{{.User.Id}}' || idsList[0] === '{{user.id}}') {
+      seenIdType = 'user-template';
+    }
+  }
+  return seenIdType;
+};
+
+const getIdActionsForResourceType = (schema, resourceType) => {
+  switch (resourceType) {
+    case 'template-multiple':
+      return [
+        '*',
+        ...schema.resourcesByType['account'].idActions,
+        ...schema.resourcesByType['user'].idActions,
+      ];
+    case 'account-template':
+      return ['*', ...schema.resourcesByType['account'].idActions];
+    case 'user-template':
+      return ['*', ...schema.resourcesByType['user'].idActions];
+    default:
+      return ['*', ...schema.resourcesByType[resourceType].idActions];
+  }
+};
+
+const validateActionsField = (
+  schema,
+  diagnostics,
+  actionList,
+  validatedFields,
+  pos,
+  translate,
+) => {
+  let validActions = schema.validActions;
+  let errorMessage = (action) =>
+    translate('actions.invalid-action', { action });
+  if (!validatedFields.type) {
+    if (validatedFields.ids?.knownType) {
+      // Only id actions belonging to known id type (including wildcard action)
+      validActions = getIdActionsForResourceType(
+        schema,
+        validatedFields.ids.knownType,
+      );
+      errorMessage = (action) =>
+        translate('actions.id-only', {
+          type: validatedFields.ids.knownType,
+          action,
+        });
+    }
+  } else if (validatedFields.type.wildcard) {
+    if (validatedFields.ids?.knownType) {
+      // Any action from associated child resource types would be valid (including wildcard action)
+      validActions = [
+        '*',
+        'no-op',
+        ...getChildResourceActions(schema, validatedFields.ids.knownType),
+      ];
+    }
+  } else if (validatedFields.type.value) {
+    if (!validatedFields.ids) {
+      // Only collection actions create/list belonging to the specified type
+      validActions =
+        schema.resourcesByType[validatedFields.type.value].collectionActions;
+      validActions = validActions.filter(
+        (action) => action.startsWith('create') || action.startsWith('list'),
+      );
+      errorMessage = (action) =>
+        translate('actions.collection-only', { action });
+    } else if (validatedFields.ids.knownType || validatedFields.ids.wildcard) {
+      // Any action belonging to the specified type (including wildcard action)
+      validActions = [
+        '*',
+        'no-op',
+        ...schema.resourcesByType[validatedFields.type.value].actions,
+      ];
+    }
+  }
+
+  let segmentStart = pos.valueStart;
+  for (const [i, action] of actionList.entries()) {
+    let segmentEnd = segmentStart + action.length;
+    if (i < actionList.length - 1) {
+      segmentEnd += 1; // Include comma delimiter for all but last action
+    }
+    if (actionList.slice(i + 1).includes(action)) {
+      diagnostics.push({
+        from: segmentStart,
+        to: segmentEnd,
+        severity: 'error',
+        message: translate('actions.duplicate-action', { action }),
+        actions: [createDeleteTextAction(translate('editor.remove'))],
+      });
+      return;
+    }
+    if (!validActions.includes(action)) {
+      diagnostics.push({
+        from: pos.valueStart,
+        to: pos.valueEnd,
+        severity: 'error',
+        message: errorMessage(action),
+      });
+      return;
+    }
+    segmentStart += action.length + 1; // +1 for comma
+  }
+
+  // no-op should be used with list action or else it has no effect.
+  // Also, no-op is not necessary if there is already any other action specified.
+  const noopAllowed = validActions.includes('no-op');
+  const hasNoOp = actionList.includes('no-op');
+  const hasList = actionList.includes('list');
+  const hasOtherActions = actionList.some(
+    (action) => action !== 'list' && action !== 'no-op',
+  );
+  if (noopAllowed) {
+    if (hasNoOp) {
+      if (!hasList) {
+        diagnostics.push({
+          from: pos.valueStart,
+          to: pos.valueEnd,
+          severity: 'error',
+          message: translate('actions.noop-requires-list'),
+        });
+        return;
+      }
+      if (hasOtherActions) {
+        diagnostics.push({
+          from: pos.valueStart,
+          to: pos.valueEnd,
+          severity: 'error',
+          message: translate('actions.noop-unnecessary'),
+        });
+        return;
+      }
+    }
+    if (hasList) {
+      if (!hasNoOp && !hasOtherActions) {
+        diagnostics.push({
+          from: pos.valueStart,
+          to: pos.valueEnd,
+          severity: 'error',
+          message: translate('actions.list-requires-noop'),
+          actions: [createAddTextAction(translate('editor.add-noop'))],
+        });
+        return;
+      }
+    }
+  }
+};
+
+export const createGrantLinter = (grantsSchema, translate) => {
+  const schema = normalizeGrantsSchema(grantsSchema);
+  return (context) => grantLinter(context, schema, translate);
+};
diff --git a/ui/admin/tests/acceptance/roles/edit-grants-test.js b/ui/admin/tests/acceptance/roles/edit-grants-test.js
index 11b897ef0..138c864a1 100644
--- a/ui/admin/tests/acceptance/roles/edit-grants-test.js
+++ b/ui/admin/tests/acceptance/roles/edit-grants-test.js
@@ -4,7 +4,14 @@
  */
 
 import { module, test } from 'qunit';
-import { visit, click, currentURL, find, select, waitFor } from '@ember/test-helpers';
+import {
+  visit,
+  click,
+  currentURL,
+  find,
+  select,
+  waitFor,
+} from '@ember/test-helpers';
 import { setupApplicationTest } from 'admin/tests/helpers';
 import * as selectors from './selectors';
 import * as commonSelectors from 'admin/tests/helpers/selectors';
diff --git a/ui/admin/tests/unit/utils/grant-linter-test.js b/ui/admin/tests/unit/utils/grant-linter-test.js
new file mode 100644
index 000000000..012a3ae11
--- /dev/null
+++ b/ui/admin/tests/unit/utils/grant-linter-test.js
@@ -0,0 +1,239 @@
+/**
+ * Copyright IBM Corp. 2021, 2026
+ * SPDX-License-Identifier: BUSL-1.1
+ */
+
+import { module, test } from 'qunit';
+import { setupTest } from 'ember-qunit';
+import { setupMirage } from 'admin/tests/helpers/mirage';
+import { setupIntl } from 'ember-intl/test-support';
+import { createGrantLinter } from 'admin/utils/grant-linter';
+
+const createContext = (lineText) => ({
+  pos: lineText.length,
+  state: {
+    doc: {
+      toString() {
+        return lineText;
+      },
+    },
+  },
+});
+
+module('Unit | Utility | grant-linter', function (hooks) {
+  setupTest(hooks);
+  setupMirage(hooks);
+  setupIntl(hooks, 'en-us');
+
+  hooks.beforeEach(async function () {
+    const response = await fetch('/grants-schema.json');
+
+    if (!response.ok) {
+      throw new Error(`Failed to fetch grants schema: ${response.status}`);
+    }
+    this.intl = this.owner.lookup('service:intl');
+    const grantsSchemaData = await response.json();
+    const translateLintingError = (key, options = {}) =>
+      this.intl.t(`resources.role.edit-grants.linting-errors.${key}`, options);
+    this.grantLinter = createGrantLinter(
+      grantsSchemaData,
+      translateLintingError,
+    );
+  });
+
+  test.each(
+    'diagnostics for syntax and formatting errors',
+    [
+      ['ids=*; type=*; actions=*', 'Whitespace is not allowed'], // whitespace around semicolons
+      ['ids=*;type= *;actions=*', 'Whitespace is not allowed'], // whitespace around equal sign
+      ['ids=*;type=*;actions=read, write', 'Whitespace is not allowed'], // whitespace around commas
+      ['ids=*;type=*;actions=read,write;', 'Trailing semicolon is not allowed'], // trailing semicolon
+      [';ids=*;type=*;actions=read,write', 'Leading semicolon is not allowed'], // leading semicolon
+      ['ids={{.Account.Id}};type=+;actions=read', 'Invalid character "+"'], // invalid character +
+      ['ids={{.Account.Id}};type=();actions=read', 'Invalid character "("'], // invalid characters ()
+      ['type=target', 'Missing "actions" or "output_fields" fields'], // missing actions/output_fields field
+      ['actions=read,write', 'Missing "ids" or "type" fields'], // missing type/ids field
+      ['ids=hc_123', 'Missing "actions" field'], // missing actions field
+      [
+        'type=credential-store;ids=;actions=read',
+        '"ids" value cannot be empty',
+      ], // empty ids value
+      ['type=;actions=read', '"type" value cannot be empty'], // empty type field
+      ['ids=csst_1234;actions=', '"actions" value cannot be empty'], // empty actions value
+      [
+        'type=credential;ids=csst_1234;actions=read,write;ids=cs_5678',
+        'Duplicate field "ids"',
+      ], // duplicate ids field
+      [
+        'type=credential;actions=read,write;type=host',
+        'Duplicate field "type"',
+      ], // duplicate type field
+      [
+        'type=credential;ids=csst_1234;actions=read,write;actions=delete',
+        'Duplicate field "actions"',
+      ], // duplicate actions field
+      [
+        'type=credential;ids=cs_1234;actions=read;random=name',
+        'Unknown field "random"',
+      ], // unknown field "random"
+      [
+        '=credential;actions=;ids=cs_1234',
+        'Invalid format: expected key=value',
+      ], // missing type key
+    ],
+    function (assert, [grantString, errorMsg]) {
+      const diagnostics = this.grantLinter(createContext(grantString));
+
+      assert.strictEqual(diagnostics[0].message, errorMsg);
+    },
+  );
+
+  test.each(
+    'diagnostics for type field values',
+    [
+      ['actions=read;type=random', 'Invalid resource type "random"'], // invalid resource type
+      ['actions=read;type=account', 'Type "account" is not a top-level type'], // invalid resource type
+      [
+        'type=credential,random;actions=read',
+        'Invalid resource type "credential,random"',
+      ], // invalid resource type
+      ['ids=*;actions=read', 'Missing "type" field for wildcard ids'], // missing type field with wildcard id
+      ['type=credential-store;actions=create'], // valid grant string
+    ],
+    function (assert, [grantString, errorMsg]) {
+      const diagnostics = this.grantLinter(createContext(grantString));
+
+      if (errorMsg) {
+        assert.strictEqual(diagnostics[0].message, errorMsg);
+      } else {
+        assert.strictEqual(diagnostics.length, 0);
+      }
+    },
+  );
+
+  test.each(
+    'diagnostics for actions field values',
+    [
+      ['type=credential-store;actions=,', 'Invalid syntax'],
+      [
+        'type=session;actions=read,*,write',
+        'Wildcard action "*" cannot be combined with other actions',
+      ], // wildcard action cannot be combined with other actions
+      [
+        'type=policy;actions=execute',
+        'Only collection actions are allowed. Invalid action "execute"',
+      ], // invalid action for resource type
+      [
+        'type=target;actions=list,no-op',
+        'Only collection actions are allowed. Invalid action "no-op"',
+      ], // invalid action when type is not specified
+      ['ids=ampw_1234;type=*;actions=read,read', 'Duplicate action "read"'], // duplicate action
+      [
+        'ids=cs_1234;actions=create',
+        'Only id actions for "credential-store" type are allowed. Invalid action "create"',
+      ], // invalid action for specific resource
+      [
+        'ids=*;type=auth-method;actions=no-op',
+        '"no-op" action should only be used with "list" action',
+      ],
+      [
+        'ids=ampw_098;type=account;actions=list',
+        '"list" action should be used with "no-op" action to have an effect',
+      ],
+      [
+        'ids=*;type=account;actions=list',
+        '"list" action should be used with "no-op" action to have an effect',
+      ],
+      [
+        'ids=ampw_098;type=account;actions=list,read,no-op',
+        '"no-op" action is unnecessary when other actions are specified',
+      ],
+      ['ids=hc_1234;type=*;actions=add-hosts,read'], // valid actions for resource type
+      ['type=worker;actions=create:controller-led'], // valid actions for resource type
+      ['type=auth-method;actions=list'], // valid actions for resource type
+    ],
+    function (assert, [grantString, errorMsg]) {
+      const diagnostics = this.grantLinter(createContext(grantString));
+
+      if (errorMsg) {
+        assert.strictEqual(diagnostics[0].message, errorMsg);
+      } else {
+        assert.strictEqual(diagnostics.length, 0);
+      }
+    },
+  );
+
+  test.each(
+    'diagnostics for ids field values',
+    [
+      ['type=credential;ids=,,,;actions=read', 'Invalid syntax'],
+      ['ids=cs_1234,cs_1234;actions=read', 'Duplicate id "cs_1234"'], // duplicate ids
+      [
+        'ids={{.Account.Id}},{{.Account.Id}};actions=read',
+        'Duplicate id "{{.Account.Id}}"',
+      ], // duplicate template ids
+      [
+        'ids={{.Account.Id}},{{account.id}};actions=read',
+        'Duplicate id "{{.Account.Id}}" and "{{account.id}}"',
+      ], // duplicate template ids
+      [
+        'ids={{.User.Id}},{{user.id}};actions=read',
+        'Duplicate id "{{.User.Id}}" and "{{user.id}}"',
+      ], // duplicate template ids
+      [
+        'actions=read;type=credential;ids=cs_1234,*,cs_5678',
+        'Wildcard id "*" cannot be combined with other ids',
+      ], // wildcard id cannot be combined with other ids
+      [
+        'ids={{.Account.Id}};type=credential;actions=read',
+        'Pinned IDs must be "credential-store" ids. Invalid id "{{.Account.Id}}"',
+      ], // template ids not valid with type specified
+      [
+        'ids=hsst_1234;type=*;actions=read',
+        'Pinned IDs must support child types. Invalid id "hsst_1234"',
+      ], // template ids not valid with type specified
+      ['ids={{.Random.Id}};actions=read', 'Unknown template "{{.Random.Id}}"'], // invalid template id
+      [
+        'type=host-catalog;ids=hcst_1234;actions=list,delete',
+        'Type "host-catalog" is not a child type of the pinned ID',
+      ], // only non-top level resource types can be pinned by id
+      [
+        'type=host-set;ids=hcst_1234,g_1234;actions=read',
+        'Ids do not have the same type. Invalid id "g_1234"',
+      ], // all ids must be valid for the resource type
+      [
+        'type=credential;ids=csst_1234,random;actions=delete',
+        'Invalid id "random"',
+      ], // all ids must be valid for the resource type
+      [
+        'ids=cs_1234,g_1234;actions=read',
+        'Ids do not have the same type. Invalid id "g_1234"',
+      ], // all ids must be same type when type is not specified
+      ['ids=none_1234,csvlt_123;actions=list', 'Invalid id "none_1234"'], // valid ids prefixes only
+      [
+        'ids=g_123,amoidc_456;type=*;actions=read,list',
+        'Pinned IDs must support child types. Invalid id "g_123"',
+      ], // all ids must support child types when type is wildcard
+      [
+        'ids=amoidc_456,hcst_123;type=*;actions=read,list',
+        'Ids do not have the same type. Invalid id "hcst_123"',
+      ], // all ids must be the same type when type is wildcard
+      ['ids=cs_1234,csst_5678;actions=read'], // valid ids when they are the same type and type is not specified
+      ['ids=*;type=*;actions=read'], // valid wildcard id
+      ['ids=hcst_123,hcplg_456;type=host-set;actions=read'], // valid pinned ids for host-set resource type
+      ['ids={{.Account.Id}};actions=read'], // valid template id when type is not specified
+      ['ids={{.Account.Id}},{{.User.Id}};actions=read'], // valid template ids when type is not specified
+      ['ids=csst_1234,csvlt_5678;actions=*'], // valid id prefixes with same type
+      ['ids=amldap_123,amoidc_456;type=*;actions=read,list'], // valid ids with wildcard type
+    ],
+    function (assert, [grantString, errorMsg]) {
+      const diagnostics = this.grantLinter(createContext(grantString));
+
+      if (errorMsg) {
+        assert.strictEqual(diagnostics[0].message, errorMsg);
+      } else {
+        assert.strictEqual(diagnostics.length, 0);
+      }
+    },
+  );
+});