fix: open local file links with Ctrl/Cmd-click

components/FileViewer.tsx

@@ -19,9 +19,9 @@ import {
   isVideoPath,
 } from "@/lib/file-types";
 import { encodeFilePathForApi, getFileDirectory, getFileName, getRelativeFilePath } from "@/lib/file-paths";
-import { resolveLocalFileHref } from "@/lib/file-links";
+import { resolveLocalFileHref, shouldOpenLocalFileInApp } from "@/lib/file-links";
 import { parseFrontmatter } from "@/lib/frontmatter";
-import { markdownPreviewRehypePlugins, markdownPreviewRemarkPlugins, normalizeDisplayMath } from "@/lib/markdown";
+import { markdownPreviewRehypePlugins, markdownPreviewRemarkPlugins, markdownUrlTransform, normalizeDisplayMath } from "@/lib/markdown";
 import { CodeBlock, MermaidBlock } from "./MermaidBlock";
 import { FrontmatterCard } from "./FrontmatterCard";
 import { parseUnifiedPatch } from "@/lib/patch";
@@ -1681,6 +1681,7 @@ function TextFileViewer({
             <ReactMarkdown
               remarkPlugins={markdownPreviewRemarkPlugins}
               rehypePlugins={markdownPreviewRehypePlugins}
+              urlTransform={onOpenFile ? markdownUrlTransform : undefined}
               components={{
                 code({ className, children, ...props }) {
                   const lang = className?.replace("language-", "").toLowerCase() ?? "";
@@ -1713,8 +1714,7 @@ function TextFileViewer({
                   }
 
                   const handleClick = (event: MouseEvent<HTMLAnchorElement>) => {
-                    if (event.defaultPrevented || event.button !== 0) return;
-                    if (event.metaKey || event.ctrlKey || event.shiftKey || event.altKey) return;
+                    if (!shouldOpenLocalFileInApp(event)) return;
                     event.preventDefault();
                     onOpenFile(linkedFile);
                   };

components/MarkdownBody.test.mjs

@@ -37,10 +37,19 @@ test("opens non-file markdown links in a safe new tab", () => {
 });
 
 test("keeps local file markdown links in the app", () => {
-  const html = renderMarkdown("[file](components/MarkdownBody.tsx)");
+  const relativeHtml = renderMarkdown("[file](components/MarkdownBody.tsx)");
+  const fileUrlHtml = renderMarkdown("[report](file:///home/me/project/report.html)");
 
-  assert.match(html, /<a href="components\/MarkdownBody\.tsx">file<\/a>/);
-  assert.doesNotMatch(html, /target=|rel=|\snode=/);
+  assert.match(relativeHtml, /<a href="components\/MarkdownBody\.tsx">file<\/a>/);
+  assert.doesNotMatch(relativeHtml, /target=|rel=|\snode=/);
+  assert.match(fileUrlHtml, /<a href="file:\/\/\/home\/me\/project\/report\.html">report<\/a>/);
+  assert.doesNotMatch(fileUrlHtml, /target=|rel=|\snode=/);
+});
+
+test("keeps file URLs inert without an in-app file handler", () => {
+  const html = renderMarkdown("[report](file:///home/me/project/report.html)", { onOpenFile: undefined });
+
+  assert.match(html, /<a href="" target="_blank" rel="noopener noreferrer">report<\/a>/);
 });
 
 test("keeps single-tilde CJK numeric ranges literal instead of striking them", () => {

components/MarkdownBody.tsx

@@ -2,9 +2,9 @@
 
 import { useMemo, type MouseEvent } from "react";
 import ReactMarkdown, { type Components } from "react-markdown";
-import { resolveLocalFileHref } from "@/lib/file-links";
+import { resolveLocalFileHref, shouldOpenLocalFileInApp } from "@/lib/file-links";
 import { encodeFilePathForApi } from "@/lib/file-paths";
-import { markdownRehypePlugins, markdownRemarkPlugins, normalizeDisplayMath } from "@/lib/markdown";
+import { markdownRehypePlugins, markdownRemarkPlugins, markdownUrlTransform, normalizeDisplayMath } from "@/lib/markdown";
 import { MermaidBlock, CodeBlock } from "./MermaidBlock";
 
 interface MarkdownBodyProps {
@@ -61,8 +61,7 @@ export function MarkdownBody({ children, className, isStreaming, cwd, onOpenFile
       }
 
       const handleClick = (event: MouseEvent<HTMLAnchorElement>) => {
-        if (event.defaultPrevented || event.button !== 0) return;
-        if (event.metaKey || event.ctrlKey || event.shiftKey || event.altKey) return;
+        if (!shouldOpenLocalFileInApp(event)) return;
         const target = event.currentTarget.getAttribute("target");
         if (target && target !== "_self") return;
         event.preventDefault();
@@ -99,6 +98,7 @@ export function MarkdownBody({ children, className, isStreaming, cwd, onOpenFile
       <ReactMarkdown
         remarkPlugins={markdownRemarkPlugins}
         rehypePlugins={markdownRehypePlugins}
+        urlTransform={onOpenFile ? markdownUrlTransform : undefined}
         components={components}
       >
         {normalizedMarkdown}

lib/file-links.test.mjs

@@ -5,6 +5,39 @@ async function loadSubject() {
   return import("./file-links.ts");
 }
 
+test("opens local files for plain, Command, and Ctrl left clicks", async () => {
+  const { shouldOpenLocalFileInApp } = await loadSubject();
+  const click = {
+    defaultPrevented: false,
+    button: 0,
+    metaKey: false,
+    ctrlKey: false,
+    shiftKey: false,
+    altKey: false,
+  };
+
+  assert.equal(shouldOpenLocalFileInApp(click), true);
+  assert.equal(shouldOpenLocalFileInApp({ ...click, metaKey: true }), true);
+  assert.equal(shouldOpenLocalFileInApp({ ...click, ctrlKey: true }), true);
+});
+
+test("leaves secondary modified and non-left clicks to the browser", async () => {
+  const { shouldOpenLocalFileInApp } = await loadSubject();
+  const click = {
+    defaultPrevented: false,
+    button: 0,
+    metaKey: false,
+    ctrlKey: false,
+    shiftKey: false,
+    altKey: false,
+  };
+
+  assert.equal(shouldOpenLocalFileInApp({ ...click, shiftKey: true }), false);
+  assert.equal(shouldOpenLocalFileInApp({ ...click, altKey: true }), false);
+  assert.equal(shouldOpenLocalFileInApp({ ...click, button: 1 }), false);
+  assert.equal(shouldOpenLocalFileInApp({ ...click, defaultPrevented: true }), false);
+});
+
 test("resolves absolute markdown file links and strips line suffixes", async () => {
   const { resolveLocalFileHref } = await loadSubject();
 
@@ -69,6 +102,21 @@ test("does not treat app or external URLs as file links", async () => {
   assert.equal(resolveLocalFileHref("//example.com/a.ts", "/home/me/project"), null);
 });
 
+test("decodes file URL paths once after parsing URL delimiters", async () => {
+  const { resolveLocalFileHref } = await loadSubject();
+
+  for (const [href, expected] of [
+    ["file:///home/me/project/C%23/report.html", "/home/me/project/C#/report.html"],
+    ["file:///home/me/project/report%3F.html", "/home/me/project/report?.html"],
+    ["file:///home/me/project/report%2520.html", "/home/me/project/report%20.html"],
+    ["file:///home/me/project/report%20one.html?raw=1#L10", "/home/me/project/report one.html"],
+    ["file:///C:/Users/me/C%23/report%2520.html", "C:/Users/me/C#/report%20.html"],
+    ["file://server/share/C%23/report%2520.html", "//server/share/C#/report%20.html"],
+  ]) {
+    assert.equal(resolveLocalFileHref(href, "/home/me/project"), expected, href);
+  }
+});
+
 test("resolves Windows file URLs without a synthetic leading slash", async () => {
   const { resolveLocalFileHref } = await loadSubject();
 

lib/file-links.ts

@@ -1,3 +1,21 @@
+interface LocalFileClickEvent {
+  defaultPrevented: boolean;
+  button: number;
+  metaKey: boolean;
+  ctrlKey: boolean;
+  shiftKey: boolean;
+  altKey: boolean;
+}
+
+export function shouldOpenLocalFileInApp(event: LocalFileClickEvent): boolean {
+  // Browsers block file:// navigation from Pi Web's HTTP origin, so the
+  // platform primary modifier must use the same in-app preview as a plain click.
+  return !event.defaultPrevented
+    && event.button === 0
+    && !event.shiftKey
+    && !event.altKey;
+}
+
 function safeDecode(value: string): string {
   try {
     return decodeURIComponent(value);
@@ -98,7 +116,8 @@ export function resolveLocalFileHref(
   }
 
   if (lowerHref.startsWith("file:")) {
-    candidate = fileUrlToPath(normalizedHref);
+    // Decode only the parsed pathname so encoded delimiters stay in the filename.
+    candidate = fileUrlToPath(cleanHref);
     candidateKind = candidate ? "absolute" : null;
   } else if (/^[a-zA-Z]:\//.test(normalizedHref)) {
     candidate = normalizedHref;

lib/markdown.ts

@@ -1,4 +1,4 @@
-import type { Options as ReactMarkdownOptions } from "react-markdown";
+import { defaultUrlTransform, type Options as ReactMarkdownOptions } from "react-markdown";
 import rehypeKatex from "rehype-katex";
 import rehypeRaw from "rehype-raw";
 import rehypeSanitize, { defaultSchema } from "rehype-sanitize";
@@ -12,9 +12,17 @@ const markdownSanitizeSchema = {
     ...defaultSchema.attributes,
     code: [["className", /^language-./, "math-inline", "math-display"]],
   },
+  protocols: {
+    ...defaultSchema.protocols,
+    href: [...(defaultSchema.protocols?.href ?? []), "file"],
+  },
   strip: [...(defaultSchema.strip || []), "iframe", "object", "style", "form"],
 };
 
+export function markdownUrlTransform(value: string): string {
+  return /^file:/i.test(value) ? value : defaultUrlTransform(value);
+}
+
 export function normalizeDisplayMath(markdown: string): string {
   const lineBreak = markdown.includes("\r\n") ? "\r\n" : "\n";
   const lines = markdown.split(/\r?\n/);