diff --git a/plug-api/app_event.ts b/plug-api/app_event.ts
index 47cace92..49b08f25 100644
--- a/plug-api/app_event.ts
+++ b/plug-api/app_event.ts
@@ -46,6 +46,11 @@ export type PublishEvent = {
   name: string;
 };
 
+export type LintEvent = {
+  name: string;
+  tree: ParseTree;
+};
+
 export type CompleteEvent = {
   pageName: string;
   linePrefix: string;
diff --git a/plugs/index/lint.ts b/plugs/index/lint.ts
index 3bd8ec01..481506a3 100644
--- a/plugs/index/lint.ts
+++ b/plugs/index/lint.ts
@@ -1,14 +1,13 @@
-import { editor, markdown, YAML } from "$sb/syscalls.ts";
+import { YAML } from "$sb/syscalls.ts";
 import { LintDiagnostic } from "$sb/types.ts";
 import {
   findNodeOfType,
   renderToText,
   traverseTreeAsync,
 } from "$sb/lib/tree.ts";
+import { LintEvent } from "$sb/app_event.ts";
 
-export async function lintYAML(): Promise<LintDiagnostic[]> {
-  const text = await editor.getText();
-  const tree = await markdown.parseMarkdown(text);
+export async function lintYAML({ tree }: LintEvent): Promise<LintDiagnostic[]> {
   const diagnostics: LintDiagnostic[] = [];
   await traverseTreeAsync(tree, async (node) => {
     if (node.type === "FrontMatterCode") {
diff --git a/plugs/query/query.plug.yaml b/plugs/query/query.plug.yaml
index 7d7d31fa..c8ac1e73 100644
--- a/plugs/query/query.plug.yaml
+++ b/plugs/query/query.plug.yaml
@@ -4,6 +4,11 @@ functions:
     path: query.ts:widget
     codeWidget: query
 
+  lintQuery:
+    path: query.ts:lintQuery
+    events:
+    - editor:lint
+
   templateWidget:
     path: template.ts:widget
     codeWidget: template
diff --git a/plugs/query/query.ts b/plugs/query/query.ts
index 3c259988..4b9f56de 100644
--- a/plugs/query/query.ts
+++ b/plugs/query/query.ts
@@ -1,10 +1,15 @@
-import type { WidgetContent } from "$sb/app_event.ts";
-import { events, language, system } from "$sb/syscalls.ts";
-import { parseTreeToAST } from "$sb/lib/tree.ts";
+import type { LintEvent, WidgetContent } from "$sb/app_event.ts";
+import { events, language, space, system } from "$sb/syscalls.ts";
+import {
+  findNodeOfType,
+  parseTreeToAST,
+  traverseTreeAsync,
+} from "$sb/lib/tree.ts";
 import { astToKvQuery } from "$sb/lib/parse-query.ts";
 import { jsonToMDTable, renderQueryTemplate } from "../directive/util.ts";
 import { loadPageObject, replaceTemplateVars } from "../template/template.ts";
-import { resolvePath } from "$sb/lib/resolve.ts";
+import { cleanPageRef, resolvePath } from "$sb/lib/resolve.ts";
+import { LintDiagnostic } from "$sb/types.ts";
 
 export async function widget(
   bodyText: string,
@@ -73,3 +78,90 @@ export async function widget(
     );
   }
 }
+
+export async function lintQuery(
+  { name, tree }: LintEvent,
+): Promise<LintDiagnostic[]> {
+  const pageObject = await loadPageObject(name);
+  const diagnostics: LintDiagnostic[] = [];
+  await traverseTreeAsync(tree, async (node) => {
+    if (node.type === "FencedCode") {
+      const codeInfo = findNodeOfType(node, "CodeInfo")!;
+      if (!codeInfo) {
+        return true;
+      }
+      const codeLang = codeInfo.children![0].text!;
+      if (
+        codeLang !== "query"
+      ) {
+        return true;
+      }
+      const codeText = findNodeOfType(node, "CodeText");
+      if (!codeText) {
+        return true;
+      }
+      const bodyText = codeText.children![0].text!;
+      try {
+        const queryAST = parseTreeToAST(
+          await language.parseLanguage(
+            "query",
+            await replaceTemplateVars(bodyText, pageObject),
+          ),
+        );
+        const parsedQuery = astToKvQuery(queryAST[1]);
+        const allSources = await allQuerySources();
+        if (
+          parsedQuery.querySource &&
+          !allSources.includes(parsedQuery.querySource)
+        ) {
+          diagnostics.push({
+            from: codeText.from!,
+            to: codeText.to!,
+            message: `Unknown query source '${parsedQuery.querySource}'`,
+            severity: "error",
+          });
+        }
+        if (parsedQuery.render) {
+          const templatePage = resolvePath(
+            name,
+            cleanPageRef(parsedQuery.render),
+          );
+          try {
+            await space.getPageMeta(templatePage);
+          } catch (e: any) {
+            diagnostics.push({
+              from: codeText.from!,
+              to: codeText.to!,
+              message: `Could not resolve template ${templatePage}`,
+              severity: "error",
+            });
+          }
+        }
+      } catch (e: any) {
+        diagnostics.push({
+          from: codeText.from!,
+          to: codeText.to!,
+          message: e.message,
+          severity: "error",
+        });
+      }
+    }
+    return false;
+  });
+  return diagnostics;
+}
+
+async function allQuerySources(): Promise<string[]> {
+  const allEvents = await events.listEvents();
+
+  const allSources = allEvents
+    .filter((eventName) =>
+      eventName.startsWith("query:") && !eventName.includes("*")
+    )
+    .map((source) => source.substring("query:".length));
+
+  const allObjectTypes: string[] = (await events.dispatchEvent("query_", {}))
+    .flat();
+
+  return [...allSources, ...allObjectTypes];
+}
diff --git a/web/cm_plugins/lint.ts b/web/cm_plugins/lint.ts
index de580d39..5e11b981 100644
--- a/web/cm_plugins/lint.ts
+++ b/web/cm_plugins/lint.ts
@@ -1,11 +1,19 @@
 import { Diagnostic, linter } from "@codemirror/lint";
 import type { Client } from "../client.ts";
+import { parse } from "../../common/markdown_parser/parse_tree.ts";
+import buildMarkdown from "../../common/markdown_parser/parser.ts";
+import { LintEvent } from "$sb/app_event.ts";
 
 export function plugLinter(client: Client) {
-  return linter(async (): Promise<Diagnostic[]> => {
+  return linter(async (view): Promise<Diagnostic[]> => {
+    const tree = parse(
+      buildMarkdown(client.system.mdExtensions),
+      view.state.sliceDoc(),
+    );
     const results = (await client.dispatchAppEvent("editor:lint", {
       name: client.currentPage!,
-    })).flat();
+      tree: tree,
+    } as LintEvent)).flat();
     return results;
   });
 }
diff --git a/website/CHANGELOG.md b/website/CHANGELOG.md
index 5c03852f..66f79827 100644
--- a/website/CHANGELOG.md
+++ b/website/CHANGELOG.md
@@ -1,6 +1,14 @@
 An attempt at documenting the changes/new features introduced in each
 release.
 
+---
+
+## Next
+* Upgraded set of emoji (completed via the :thinking_face: syntax) to 15.1 (so more emoji)
+* General support for highlighting errors (underlined) in the editor. Currently implemented for:
+  * All YAML fenced code blocks (and [[Frontmatter]]): will now highlight YAML parse errors
+  * [[Live Queries]]: will highlight non-existing query sources and non-existing template references in `render` clauses
+
 ---
 ## 0.5.6
 * Various optimization and bug fixes