fix(files): keep large source previews responsive (#3665)

Large read-only files bypassed the editor's virtualization and eagerly mounted every highlighted token, which could stall the renderer for seconds and consume gigabytes of memory. Route source previews through bounded platform renderers and reject reads above their display budgets before accumulation.
2026-08-22 10:13:31 +02:00
parent 8905ad4160
commit c763b80824
22 changed files with 589 additions and 183 deletions
@@ -0,0 +1,131 @@
+import { useEffect, useRef } from "react";
+import { Compartment, EditorState } from "@codemirror/state";
+import { EditorView } from "@codemirror/view";
+import { getLanguageForFile } from "@getpaseo/highlight";
+import type { WorkspaceFileLocation } from "@/workspace/file-open";
+import type { EditorVisualTheme } from "../editor/extensions.web";
+import { editorTheme } from "../editor/extensions.web";
+import { selectSourcePresentation, type SourcePresentation } from "./presentation";
+
+interface FileSourceViewProps {
+  content: string;
+  filename: string;
+  location: WorkspaceFileLocation;
+  navigationRevision: number;
+  size: number;
+  theme: EditorVisualTheme;
+  tooLargeMessage: string;
+}
+
+const languageCompartment = new Compartment();
+const themeCompartment = new Compartment();
+
+export function FileSourceView({
+  content,
+  filename,
+  location,
+  navigationRevision,
+  size,
+  theme,
+  tooLargeMessage,
+}: FileSourceViewProps) {
+  const presentation = selectSourcePresentation({ size, platform: "web" });
+  if (presentation === "unsupported") {
+    return (
+      <div data-testid="file-source-too-large" style={UNSUPPORTED_STYLE}>
+        {tooLargeMessage}
+      </div>
+    );
+  }
+  return (
+    <ReadonlyCodeMirror
+      content={content}
+      filename={filename}
+      location={location}
+      navigationRevision={navigationRevision}
+      presentation={presentation}
+      theme={theme}
+    />
+  );
+}
+
+function ReadonlyCodeMirror({
+  content,
+  filename,
+  location,
+  navigationRevision,
+  presentation,
+  theme,
+}: Omit<FileSourceViewProps, "size" | "tooLargeMessage"> & {
+  presentation: Exclude<SourcePresentation, "unsupported">;
+}) {
+  const hostRef = useRef<HTMLDivElement>(null);
+  const viewRef = useRef<EditorView | null>(null);
+  const initial = useRef({ content, filename, presentation, theme });
+
+  useEffect(() => {
+    if (!hostRef.current) return;
+    const values = initial.current;
+    const view = new EditorView({
+      parent: hostRef.current,
+      state: EditorState.create({
+        doc: values.content,
+        extensions: [
+          EditorState.readOnly.of(true),
+          EditorView.editable.of(false),
+          languageCompartment.of(
+            languageFor({ filename: values.filename, presentation: values.presentation }),
+          ),
+          themeCompartment.of(editorTheme(values.theme)),
+        ],
+      }),
+    });
+    viewRef.current = view;
+    return () => {
+      view.destroy();
+      viewRef.current = null;
+    };
+  }, []);
+
+  useEffect(() => {
+    const view = viewRef.current;
+    if (!view || view.state.doc.toString() === content) return;
+    view.dispatch({ changes: { from: 0, to: view.state.doc.length, insert: content } });
+  }, [content]);
+
+  useEffect(() => {
+    viewRef.current?.dispatch({
+      effects: [
+        languageCompartment.reconfigure(languageFor({ filename, presentation })),
+        themeCompartment.reconfigure(editorTheme(theme)),
+      ],
+    });
+  }, [filename, presentation, theme]);
+
+  useEffect(() => {
+    const view = viewRef.current;
+    if (!view || !location.lineStart) return;
+    const line = Math.min(location.lineStart, view.state.doc.lines);
+    const from = view.state.doc.line(line).from;
+    view.dispatch({ effects: EditorView.scrollIntoView(from, { y: "center" }) });
+  }, [location.lineStart, navigationRevision]);
+
+  return <div ref={hostRef} data-testid="file-source-editor" style={HOST_STYLE} />;
+}
+
+function languageFor(input: {
+  filename: string;
+  presentation: Exclude<SourcePresentation, "unsupported">;
+}) {
+  return input.presentation === "highlighted"
+    ? (getLanguageForFile(input.filename)?.extension ?? [])
+    : [];
+}
+
+const HOST_STYLE = { flex: 1, minHeight: 0, overflow: "hidden" } as const;
+const UNSUPPORTED_STYLE = {
+  alignItems: "center",
+  display: "flex",
+  flex: 1,
+  justifyContent: "center",
+} as const;