diff --git a/packages/core/src/editor/managers/StateManager.test.ts b/packages/core/src/editor/managers/StateManager.test.ts
index 22eeed4dbc..00ac28c9d8 100644
--- a/packages/core/src/editor/managers/StateManager.test.ts
+++ b/packages/core/src/editor/managers/StateManager.test.ts
@@ -1,5 +1,5 @@
 /** @vitest-environment jsdom */
-import { Plugin } from "prosemirror-state";
+import { Plugin, TextSelection } from "prosemirror-state";
 import {
   afterEach,
   beforeEach,
@@ -8,6 +8,9 @@ import {
   it,
   vi,
 } from "vite-plus/test";
+import { BlockNoteSchema } from "../../blocks/BlockNoteSchema.js";
+import { SourceInlineContentWithPreviewExtension } from "../../extensions/SourceInlineContentWithPreview/SourceInlineContentWithPreview.js";
+import { createInlineContentSpec } from "../../schema/inlineContent/createSpec.js";
 import { BlockNoteEditor } from "../BlockNoteEditor.js";
 import { createExtension } from "../BlockNoteExtension.js";
 
@@ -26,6 +29,65 @@ describe("StateManager editability", () => {
     prosemirrorPlugins: [new Plugin({ props: { editable: () => false } })],
   }));
 
+  it.each(["application", "plugin"] as const)(
+    "reconciles inline popup state after remounting with the %s restriction",
+    (source) => {
+      editor.unmount();
+      const preview = createInlineContentSpec(
+        { type: "preview", propSchema: {}, content: "plain" },
+        {
+          meta: { hasPreview: true },
+          render() {
+            const dom = document.createElement("span");
+            return { dom, contentDOM: dom };
+          },
+        },
+      );
+      const schema = BlockNoteSchema.create().extend({
+        inlineContentSpecs: { preview },
+      });
+      const previewEditor = BlockNoteEditor.create({
+        schema,
+        extensions: source === "plugin" ? [restriction()] : [],
+        initialContent: [
+          { type: "paragraph", content: [{ type: "preview", content: "x" }] },
+        ],
+      });
+      const host = document.createElement("div");
+      try {
+        previewEditor.mount(host);
+        let previewPos = -1;
+        previewEditor.prosemirrorState.doc.descendants((node, pos) => {
+          if (node.type.name === "preview") {
+            previewPos = pos;
+          }
+        });
+        expect(previewPos).toBeGreaterThan(0);
+        previewEditor.transact((tr) =>
+          tr.setSelection(TextSelection.create(tr.doc, previewPos + 1)),
+        );
+        const popup = previewEditor.getExtension(
+          SourceInlineContentWithPreviewExtension,
+        )!;
+        expect(popup.store.state.selected).toBe(
+          source === "plugin" ? undefined : previewPos,
+        );
+        previewEditor.unmount();
+        if (source === "application") {
+          previewEditor.isEditable = false;
+        }
+        previewEditor.mount(host);
+        expect(previewEditor.isEditable).toBe(false);
+        expect(previewEditor.prosemirrorState.selection.from).toBe(
+          previewPos + 1,
+        );
+        expect(popup.store.state.selected).toBeUndefined();
+      } finally {
+        previewEditor.unmount();
+      }
+    },
+  );
+
   it.each(["mount", "register", "replace", "unregister"] as const)(
     "allows editability subscribers to register plugins during %s without duplicate views",
     (operation) => {
diff --git a/packages/core/src/extensions/SourceInlineContentWithPreview/SourceInlineContentWithPreview.ts b/packages/core/src/extensions/SourceInlineContentWithPreview/SourceInlineContentWithPreview.ts
index 9ab67e93a7..f15c5ce470 100644
--- a/packages/core/src/extensions/SourceInlineContentWithPreview/SourceInlineContentWithPreview.ts
+++ b/packages/core/src/extensions/SourceInlineContentWithPreview/SourceInlineContentWithPreview.ts
@@ -14,7 +14,8 @@ import {
  * rather than the extension being configured with a type.
  *
  * Unlike the block version, the popup isn't toggled with a separate state flag:
- * it's open exactly when the selection is inside the inline content's source.
+ * it's open when the editor is editable and the selection is inside the inline
+ * content's source.
  * The store therefore only tracks which inline content (by its position) holds
  * the selection - moving the selection in opens its popup, moving it out closes
  * it. Since the source popup is always laid out (just hidden via opacity), the
@@ -38,7 +39,7 @@ export const SourceInlineContentWithPreviewExtension = createExtension(
         ?.hasPreview;
 
     // Moves the selection out of the inline content, to just `"before"` or
-    // `"after"` it, which closes the popup via the selection-change handler
+    // `"after"` it, which closes the popup via the selection listener
     // below. Lets the keyboard commit-and-exit the source the same way arrowing
     // past its edge does, keeps Enter from splitting the block while editing the
     // source, and lets the up/down arrows step out of the source rather than
@@ -92,19 +93,31 @@ export const SourceInlineContentWithPreviewExtension = createExtension(
         },
       },
       mount: ({ dom, signal }) => {
-        // The popup is open exactly when the selection is inside the inline
-        // content, so we just track which inline content (if any) holds it.
-        const unsubscribeSelectionChange = editor.onSelectionChange(() => {
-          const { $from } = editor.prosemirrorState.selection;
-          const node = $from.node();
-
-          store.setState({
-            selected: nodeHasPreview(node.type.name)
-              ? $from.before()
-              : undefined,
+        function updateSelected() {
+          if (!editor.isEditable) {
+            store.setState({ selected: undefined });
+            return;
+          }
+          editor.transact((tr) => {
+            const { $from } = tr.selection;
+            store.setState({
+              selected: nodeHasPreview($from.node().type.name)
+                ? $from.before()
+                : undefined,
+            });
           });
-        });
-        signal.addEventListener("abort", unsubscribeSelectionChange);
+        }
+        signal.addEventListener(
+          "abort",
+          editor.onSelectionChange(updateSelected),
+        );
+        signal.addEventListener(
+          "abort",
+          editor.onEditableChange(updateSelected),
+        );
+        // Selection and editability may have changed while this extension was
+        // unmounted, when neither subscription was attached.
+        updateSelected();
 
         // Sets `visibility: hidden` on the popup for a single frame when pressing up/down arrow
         // keys. The popup is normally hidden through `opacity: 0`, which means it's still visible
diff --git a/packages/diagram-block/src/block/sourcePopup.browser.test.tsx b/packages/diagram-block/src/block/sourcePopup.browser.test.tsx
new file mode 100644
index 0000000000..86a397ad41
--- /dev/null
+++ b/packages/diagram-block/src/block/sourcePopup.browser.test.tsx
@@ -0,0 +1,73 @@
+import "@blocknote/core/style.css";
+
+import { BlockNoteEditor, BlockNoteSchema } from "@blocknote/core";
+import { SourceBlockWithPreviewExtension } from "@blocknote/core/extensions";
+import { BlockNoteViewRaw } from "@blocknote/react";
+import { flushSync } from "react-dom";
+import { createRoot } from "react-dom/client";
+import { expect, it, vi } from "vite-plus/test";
+import { userEvent } from "vite-plus/test/browser";
+
+import { createReactDiagramBlockSpec } from "./createReactDiagramBlockSpec.js";
+
+const schema = BlockNoteSchema.create().extend({
+  blockSpecs: { diagram: createReactDiagramBlockSpec() },
+});
+
+it.each([false, true])(
+  "only opens a diagram preview on click when editable (editable: %s)",
+  async (editable) => {
+    const editor = BlockNoteEditor.create({
+      schema,
+      trailingBlock: false,
+      initialContent: [
+        { id: "diagram", type: "diagram", content: "graph TD; A --> B" },
+      ],
+    });
+    const host = document.createElement("div");
+    document.body.append(host);
+    const root = createRoot(host);
+
+    try {
+      flushSync(() => {
+        root.render(<BlockNoteViewRaw editor={editor} editable={editable} />);
+      });
+
+      const preview = await vi.waitFor(() => {
+        const preview = host.querySelector<HTMLElement>("[role='img']");
+        if (!preview) {
+          throw new Error("Diagram preview not rendered yet");
+        }
+        return preview;
+      });
+      const extension = editor.getExtension(SourceBlockWithPreviewExtension)!;
+      flushSync(() => editor.setTextCursorPosition("diagram", "end"));
+      expect(extension.store.state.selected).toBe("diagram");
+      // Unlike inline math, selecting a diagram never opens its popup.
+      expect(extension.store.state.popupOpen).toBeUndefined();
+
+      await userEvent.click(preview);
+      expect(extension.store.state.popupOpen).toBe(
+        editable ? "diagram" : undefined,
+      );
+      await vi.waitFor(() =>
+        expect(
+          host
+            .querySelector(".bn-preview-with-source-popup")
+            ?.getAttribute("data-open"),
+        ).toBe(String(editable)),
+      );
+
+      if (!editable) {
+        const content = editor.getBlock("diagram")?.content;
+        await userEvent.keyboard("{Enter}");
+        expect(extension.store.state.popupOpen).toBeUndefined();
+        expect(editor.getBlock("diagram")?.content).toEqual(content);
+      }
+    } finally {
+      root.unmount();
+      editor._tiptapEditor.destroy();
+      host.remove();
+    }
+  },
+);
diff --git a/packages/math-block/src/inlineContent/sourcePopup.browser.test.tsx b/packages/math-block/src/inlineContent/sourcePopup.browser.test.tsx
new file mode 100644
index 0000000000..eecf915eb0
--- /dev/null
+++ b/packages/math-block/src/inlineContent/sourcePopup.browser.test.tsx
@@ -0,0 +1,169 @@
+import "@blocknote/core/style.css";
+
+import {
+  BlockNoteEditor,
+  BlockNoteSchema,
+  createExtension,
+} from "@blocknote/core";
+import { SourceInlineContentWithPreviewExtension } from "@blocknote/core/extensions";
+import { BlockNoteViewRaw } from "@blocknote/react";
+import { Plugin, TextSelection } from "prosemirror-state";
+import { flushSync } from "react-dom";
+import { createRoot } from "react-dom/client";
+import { expect, it, vi } from "vite-plus/test";
+
+import { createReactInlineMathSpec } from "./createReactMathInlineContentSpec.js";
+
+const schema = BlockNoteSchema.create().extend({
+  inlineContentSpecs: { math: createReactInlineMathSpec() },
+});
+
+it.each([
+  { editable: false, batched: false, pluginReadOnly: false },
+  { editable: true, batched: false, pluginReadOnly: false },
+  { editable: true, batched: true, pluginReadOnly: false },
+  { editable: true, batched: false, pluginReadOnly: true },
+  { editable: true, batched: true, pluginReadOnly: true },
+])(
+  "inline math popup follows editability (#3291): %j",
+  async ({ editable, batched, pluginReadOnly }) => {
+    const pluginEditability = createExtension(() => ({
+      key: "testPluginEditability",
+      prosemirrorPlugins: [
+        new Plugin({ props: { editable: () => !pluginReadOnly } }),
+      ],
+    }));
+    const editor = BlockNoteEditor.create({
+      schema,
+      extensions: [pluginEditability()],
+      trailingBlock: false,
+      initialContent: [
+        {
+          type: "paragraph",
+          content: [{ type: "math", content: "x^2" }],
+        },
+      ],
+    });
+    const host = document.createElement("div");
+    document.body.append(host);
+    const root = createRoot(host);
+
+    try {
+      flushSync(() => {
+        root.render(<BlockNoteViewRaw editor={editor} editable={editable} />);
+      });
+
+      let mathPos: number | undefined;
+      editor.prosemirrorState.doc.descendants((node, pos) => {
+        if (node.type.name === "math") {
+          mathPos = pos;
+        }
+      });
+      if (mathPos === undefined) {
+        throw new Error("Inline math node not found");
+      }
+      const sourcePos = mathPos + 1;
+
+      async function expectPopup(open: boolean) {
+        expect(editor.prosemirrorState.selection.from).toBe(sourcePos);
+        expect(
+          editor.getExtension(SourceInlineContentWithPreviewExtension)!.store
+            .state.selected,
+        ).toBe(open ? mathPos : undefined);
+        await vi.waitFor(() =>
+          expect(
+            host
+              .querySelector(".bn-preview-with-source-popup")
+              ?.getAttribute("data-open"),
+          ).toBe(String(open)),
+        );
+      }
+
+      // Read-only ProseMirror views still move the selection on click. Exercise
+      // that selection path directly, independently of the guarded preview click.
+      flushSync(() => {
+        editor.transact((tr) =>
+          tr.setSelection(TextSelection.create(tr.doc, sourcePos)),
+        );
+      });
+
+      await expectPopup(editable && !pluginReadOnly);
+
+      if (editable) {
+        flushSync(() => {
+          if (batched) {
+            editor.transact(() => {
+              editor.isEditable = false;
+            });
+          } else {
+            editor.isEditable = false;
+          }
+        });
+
+        await expectPopup(false);
+
+        flushSync(() => {
+          if (batched) {
+            editor.transact(() => {
+              editor.isEditable = true;
+            });
+          } else {
+            editor.isEditable = true;
+          }
+        });
+
+        await expectPopup(!pluginReadOnly);
+      }
+    } finally {
+      root.unmount();
+      editor._tiptapEditor.destroy();
+      host.remove();
+    }
+  },
+);
+
+it("tracks inline source popups through the editor API", () => {
+  const editor = BlockNoteEditor.create({
+    schema,
+    initialContent: [
+      { type: "paragraph", content: [{ type: "math", content: "x^2" }] },
+    ],
+  });
+  const host = document.createElement("div");
+  document.body.append(host);
+
+  try {
+    editor.mount(host);
+    expect(editor.prosemirrorView).toBeDefined();
+    let mathPos: number | undefined;
+    editor.prosemirrorState.doc.descendants((node, pos) => {
+      if (node.type.name === "math") {
+        mathPos = pos;
+      }
+    });
+    if (mathPos === undefined) {
+      throw new Error("Inline math node not found");
+    }
+    const sourcePos = mathPos + 1;
+    editor.transact((tr) =>
+      tr.setSelection(TextSelection.create(tr.doc, sourcePos)),
+    );
+    expect(
+      editor.getExtension(SourceInlineContentWithPreviewExtension)!.store.state
+        .selected,
+    ).toBe(mathPos);
+    editor.isEditable = false;
+    expect(
+      editor.getExtension(SourceInlineContentWithPreviewExtension)!.store.state
+        .selected,
+    ).toBeUndefined();
+    editor.isEditable = true;
+    expect(
+      editor.getExtension(SourceInlineContentWithPreviewExtension)!.store.state
+        .selected,
+    ).toBe(mathPos);
+  } finally {
+    editor._tiptapEditor.destroy();
+    host.remove();
+  }
+});