fix(web): open markdown file links that climb out of the workspace

apps/web/src/markdown-links.test.ts

@@ -254,6 +254,119 @@ describe("resolveMarkdownFileLinkTarget", () => {
     });
   });
 
+  it("opens a parent link outside the workspace as a host file", () => {
+    expect(resolveMarkdownFileLinkMeta("../other/notes.md", "/home/me/project")).toMatchObject({
+      filePath: "/home/me/other/notes.md",
+      targetPath: "/home/me/other/notes.md",
+      workspaceRelativePath: null,
+    });
+    expect(resolveInlineCodeFileLinkMeta("../other/notes.md", "/home/me/project")).toMatchObject({
+      filePath: "/home/me/other/notes.md",
+      workspaceRelativePath: null,
+    });
+    expect(
+      resolveMarkdownFileLinkMeta("/home/me/project/../other/notes.md", "/home/me/project"),
+    ).toMatchObject({
+      filePath: "/home/me/other/notes.md",
+      workspaceRelativePath: null,
+    });
+  });
+
+  it("keeps an in-workspace parent link inside the workspace", () => {
+    expect(
+      resolveMarkdownFileLinkMeta("docs/guide/../readme.md", "/home/me/project"),
+    ).toMatchObject({
+      filePath: "/home/me/project/docs/readme.md",
+      targetPath: "/home/me/project/docs/readme.md",
+      workspaceRelativePath: "docs/readme.md",
+    });
+    expect(
+      resolveMarkdownFileLinkMeta(
+        "../readme.md",
+        "/home/me/project",
+        "/home/me/project/docs/guide",
+      ),
+    ).toMatchObject({
+      filePath: "/home/me/project/docs/readme.md",
+      workspaceRelativePath: "docs/readme.md",
+    });
+  });
+
+  it("keeps a line suffix on a collapsed parent link", () => {
+    expect(resolveMarkdownFileLinkMeta("../other/notes.md:12:3", "/home/me/project")).toMatchObject(
+      {
+        filePath: "/home/me/other/notes.md",
+        targetPath: "/home/me/other/notes.md:12:3",
+        line: 12,
+        column: 3,
+        workspaceRelativePath: null,
+      },
+    );
+    expect(
+      resolveMarkdownFileLinkMeta("docs/guide/../readme.md:4", "/home/me/project"),
+    ).toMatchObject({
+      filePath: "/home/me/project/docs/readme.md",
+      targetPath: "/home/me/project/docs/readme.md:4",
+      line: 4,
+      workspaceRelativePath: "docs/readme.md",
+    });
+  });
+
+  it("expands a home path before collapsing parent segments", () => {
+    expect(resolveMarkdownFileLinkMeta("~/other/../notes.md:4", "/home/me/project")).toMatchObject({
+      filePath: "/home/me/notes.md",
+      targetPath: "/home/me/notes.md:4",
+      line: 4,
+      workspaceRelativePath: null,
+    });
+    expect(
+      resolveMarkdownFileLinkMeta("~/other/../notes.md", "C:\\Users\\me\\project"),
+    ).toMatchObject({
+      filePath: "C:\\Users\\me\\notes.md",
+      workspaceRelativePath: null,
+    });
+  });
+
+  it("does not climb above a Windows drive root", () => {
+    expect(resolveMarkdownFileLinkMeta("../notes.md", "C:\\")).toMatchObject({
+      filePath: "C:\\notes.md",
+      workspaceRelativePath: "notes.md",
+    });
+    expect(resolveMarkdownFileLinkMeta("../../notes.md", "C:\\repo")).toMatchObject({
+      filePath: "C:\\notes.md",
+      workspaceRelativePath: null,
+    });
+    expect(resolveMarkdownFileLinkMeta("C:/foo/../../bar.md", "D:\\repo")).toMatchObject({
+      filePath: "C:/bar.md",
+      workspaceRelativePath: null,
+    });
+  });
+
+  it("keeps a UNC share when a relative link climbs out of the project", () => {
+    expect(resolveMarkdownFileLinkMeta("../file.md", "//server/share/project")).toMatchObject({
+      filePath: "//server/share/file.md",
+      targetPath: "//server/share/file.md",
+      workspaceRelativePath: null,
+    });
+    expect(resolveMarkdownFileLinkMeta("../file.md", "\\\\server\\share\\project")).toMatchObject({
+      filePath: "\\\\server\\share\\file.md",
+      workspaceRelativePath: null,
+    });
+    expect(
+      resolveMarkdownFileLinkMeta(
+        "\\\\server\\share\\project\\..\\file.md",
+        "\\\\server\\share\\project",
+      ),
+    ).toMatchObject({
+      filePath: "\\\\server\\share\\file.md",
+      workspaceRelativePath: null,
+    });
+    expect(resolveMarkdownFileLinkMeta("dir/../file.md", "//server/share/project")).toMatchObject({
+      filePath: "//server/share/project/file.md",
+      workspaceRelativePath: "file.md",
+    });
+  });
+
   it("does not classify a case-distinct POSIX sibling as a workspace file", () => {
     expect(
       resolveMarkdownFileLinkMeta(

apps/web/src/markdown-links.ts

@@ -12,7 +12,11 @@ import {
 } from "@t3tools/client-runtime/markdown-links";
 
 import { formatWorkspaceRelativePath } from "./filePathDisplay";
-import { isTerminalLinkActivation, resolvePathLinkTarget } from "./terminal-links";
+import {
+  collapseLexicalDotSegments,
+  isTerminalLinkActivation,
+  resolvePathLinkTarget,
+} from "./terminal-links";
 
 export { normalizeMarkdownLinkDestination };
 
@@ -63,6 +67,10 @@ export function rewriteMarkdownFileUriHref(href: string | undefined): string | n
  * `baseDir` anchors relative links; it defaults to the workspace root and is the
  * file's own directory when rendering a markdown file. `cwd` stays the workspace
  * root so the result still knows whether the target is inside it.
+ *
+ * `.` and `..` collapse lexically on the resolved path, after `~/` expansion,
+ * before workspace membership is decided. A link that climbs out of the workspace
+ * becomes an absolute host path. A `:line` or `:line:column` suffix is kept.
  */
 export function resolveMarkdownFileLinkTarget(
   href: string | undefined,
@@ -74,9 +82,11 @@ export function resolveMarkdownFileLinkTarget(
   if (!target) return null;
 
   const pathWithPosition = formatFilePathPosition(target);
-  if (!isRelativeFilePath(pathWithPosition)) return pathWithPosition;
+  if (!isRelativeFilePath(pathWithPosition)) {
+    return collapseLexicalDotSegments(pathWithPosition);
+  }
   if (!baseDir) return null;
-  return resolvePathLinkTarget(pathWithPosition, baseDir);
+  return collapseLexicalDotSegments(resolvePathLinkTarget(pathWithPosition, baseDir));
 }
 
 /**

apps/web/src/terminal-links.test.ts

@@ -1,6 +1,7 @@
 import { describe, expect, it } from "vite-plus/test";
 
 import {
+  collapseLexicalDotSegments,
   collectWrappedTerminalLinkLine,
   extractTerminalLinks,
   isTerminalLinkActivation,
@@ -200,6 +201,96 @@ describe("resolvePathLinkTarget", () => {
   });
 });
 
+describe("collapseLexicalDotSegments", () => {
+  it("collapses a parent link that leaves the workspace", () => {
+    expect(collapseLexicalDotSegments("/home/me/project/../other/notes.md")).toBe(
+      "/home/me/other/notes.md",
+    );
+  });
+
+  it("collapses an in-workspace parent segment", () => {
+    expect(collapseLexicalDotSegments("/home/me/project/docs/guide/../readme.md")).toBe(
+      "/home/me/project/docs/readme.md",
+    );
+    expect(collapseLexicalDotSegments("/home/me/project/docs/./readme.md")).toBe(
+      "/home/me/project/docs/readme.md",
+    );
+  });
+
+  it("keeps a line and column suffix while collapsing the path", () => {
+    expect(collapseLexicalDotSegments("/home/me/project/../other/notes.md:12:3")).toBe(
+      "/home/me/other/notes.md:12:3",
+    );
+    expect(collapseLexicalDotSegments("/home/me/project/docs/guide/../readme.md:4")).toBe(
+      "/home/me/project/docs/readme.md:4",
+    );
+  });
+
+  it("keeps a forward-slash UNC share when collapsing parent segments", () => {
+    expect(collapseLexicalDotSegments("//server/share/dir/../file.md")).toBe(
+      "//server/share/file.md",
+    );
+    expect(collapseLexicalDotSegments("//server/share/../file.md")).toBe("//server/share/file.md");
+    expect(collapseLexicalDotSegments("//server/share/dir/../../file.md")).toBe(
+      "//server/share/file.md",
+    );
+    expect(collapseLexicalDotSegments("//server/share/dir/../file.md:12:3")).toBe(
+      "//server/share/file.md:12:3",
+    );
+  });
+
+  it("keeps a backslash UNC share when collapsing parent segments", () => {
+    expect(collapseLexicalDotSegments("\\\\server\\share\\dir\\..\\file.md")).toBe(
+      "\\\\server\\share\\file.md",
+    );
+    expect(collapseLexicalDotSegments("\\\\server\\share\\..\\file.md")).toBe(
+      "\\\\server\\share\\file.md",
+    );
+    expect(collapseLexicalDotSegments("\\\\server\\share\\dir\\..\\..\\file.md")).toBe(
+      "\\\\server\\share\\file.md",
+    );
+  });
+
+  it("does not climb above a POSIX root or a Windows drive root", () => {
+    expect(collapseLexicalDotSegments("/../file.md")).toBe("/file.md");
+    expect(collapseLexicalDotSegments("/../../file.md")).toBe("/file.md");
+    expect(collapseLexicalDotSegments("C:\\foo\\..\\..\\bar.md")).toBe("C:\\bar.md");
+    expect(collapseLexicalDotSegments("C:/foo/../../bar.md")).toBe("C:/bar.md");
+    expect(collapseLexicalDotSegments("C:\\..\\bar.md")).toBe("C:\\bar.md");
+    expect(collapseLexicalDotSegments("C:/../bar.md")).toBe("C:/bar.md");
+  });
+
+  it("leaves an incomplete UNC path unchanged", () => {
+    expect(collapseLexicalDotSegments("//server/../file.md")).toBe("//server/../file.md");
+    expect(collapseLexicalDotSegments("\\\\server\\..\\file.md")).toBe("\\\\server\\..\\file.md");
+  });
+
+  it("preserves separators on a path with no dot segment", () => {
+    expect(collapseLexicalDotSegments("/tmp/favicons/")).toBe("/tmp/favicons/");
+    expect(collapseLexicalDotSegments("//server/share/file.md")).toBe("//server/share/file.md");
+    expect(collapseLexicalDotSegments("\\\\server\\share\\file.md")).toBe(
+      "\\\\server\\share\\file.md",
+    );
+    expect(collapseLexicalDotSegments("C:/foo/bar.md:12")).toBe("C:/foo/bar.md:12");
+    expect(collapseLexicalDotSegments("C:\\foo\\bar\\")).toBe("C:\\foo\\bar\\");
+    expect(collapseLexicalDotSegments("docs/my.file/readme.md")).toBe("docs/my.file/readme.md");
+  });
+
+  it("preserves a trailing separator after collapsing", () => {
+    expect(collapseLexicalDotSegments("/proj/docs/guide/../")).toBe("/proj/docs/");
+    expect(collapseLexicalDotSegments("C:\\foo\\..\\")).toBe("C:\\");
+    expect(collapseLexicalDotSegments("//server/share/dir/../")).toBe("//server/share/");
+    expect(collapseLexicalDotSegments("\\\\server\\share\\dir\\..\\")).toBe("\\\\server\\share\\");
+    expect(collapseLexicalDotSegments("docs/guide/../")).toBe("docs/");
+    expect(collapseLexicalDotSegments("foo/../")).toBe("./");
+  });
+
+  it("collapses a home-relative path without climbing above ~", () => {
+    expect(collapseLexicalDotSegments("~/other/../notes.md:4")).toBe("~/notes.md:4");
+    expect(collapseLexicalDotSegments("~\\other\\..\\notes.md")).toBe("~\\notes.md");
+  });
+});
+
 describe("isTerminalLinkActivation", () => {
   it("requires cmd on macOS", () => {
     expect(

apps/web/src/terminal-links.ts

@@ -222,3 +222,116 @@ export function resolvePathLinkTarget(rawPath: string, cwd: string): string {
 
   return formatFilePathPosition({ ...position, path: resolvedPath });
 }
+
+/**
+ * Collapses `.` and `..` on a markdown file-link path before workspace membership
+ * is decided. The collapse is lexical and does not read the filesystem.
+ *
+ * POSIX `/`, a Windows drive root (`C:\` or `C:/`), a backslash UNC share
+ * (`\\server\share`), and a forward-slash UNC share (`//server/share`) stay
+ * intact, and `..` does not climb above them. A `:line` or `:line:column`
+ * suffix is preserved. A path with no `.` or `..` segment is returned unchanged.
+ */
+export function collapseLexicalDotSegments(pathWithPosition: string): string {
+  const position = splitFilePathPosition(pathWithPosition);
+  if (!position.path.split(/[\\/]/).some((segment) => segment === "." || segment === "..")) {
+    return pathWithPosition;
+  }
+  return formatFilePathPosition({
+    ...position,
+    path: collapseDotSegments(position.path),
+  });
+}
+
+/**
+ * Removes `.` and `..` under the path's root. A complete UNC share is recognized
+ * before a single `/`, so `//server/share/dir/..` stays on that share. An
+ * incomplete UNC path is returned unchanged.
+ */
+function collapseDotSegments(path: string): string {
+  const unc = uncSharePrefix(path);
+  if ((path.startsWith("//") || path.startsWith("\\\\")) && !unc) return path;
+
+  const trailing = /[\\/]$/.test(path);
+  let prefix = "";
+  let rest = path;
+  let separator: "/" | "\\" = path.includes("\\") ? "\\" : "/";
+  let rooted = false;
+
+  if (unc) {
+    prefix = unc.prefix;
+    separator = unc.separator;
+    rooted = true;
+    rest = path.slice(prefix.length);
+  } else {
+    const drive = /^[A-Za-z]:/.exec(path);
+    if (drive?.[0]) {
+      prefix = drive[0];
+      const driveSeparator = path.charAt(prefix.length);
+      rooted = driveSeparator === "/" || driveSeparator === "\\";
+      separator = driveSeparator === "\\" || (!rooted && path.includes("\\")) ? "\\" : "/";
+      rest = path.slice(prefix.length);
+    } else if (path.startsWith("/")) {
+      prefix = "/";
+      separator = "/";
+      rooted = true;
+      rest = path.slice(1);
+    } else if (path.startsWith("~/") || path.startsWith("~\\")) {
+      separator = path.charAt(1) === "\\" ? "\\" : "/";
+      prefix = path.slice(0, 2);
+      rooted = true;
+      rest = path.slice(2);
+    }
+  }
+
+  const segments: string[] = [];
+  for (const segment of rest.split(/[\\/]/)) {
+    if (segment.length === 0 || segment === ".") continue;
+    if (segment === "..") {
+      if (segments.length > 0 && segments.at(-1) !== "..") segments.pop();
+      else if (!rooted) segments.push("..");
+      continue;
+    }
+    segments.push(segment);
+  }
+
+  if (segments.length === 0) {
+    if (prefix === "/") return "/";
+    if (/^[A-Za-z]:$/.test(prefix)) return rooted ? `${prefix}${separator}` : prefix;
+    if (prefix.startsWith("//") || prefix.startsWith("\\\\")) return `${prefix}${separator}`;
+    if (prefix === "~/" || prefix === "~\\") return prefix;
+    return prefix.length > 0 ? prefix : trailing ? `.${separator}` : ".";
+  }
+
+  const body = segments.join(separator);
+  const joined =
+    prefix.length === 0
+      ? body
+      : prefix.endsWith("/") || prefix.endsWith("\\")
+        ? `${prefix}${body}`
+        : rooted
+          ? `${prefix}${separator}${body}`
+          : `${prefix}${body}`;
+  return trailing ? `${joined}${separator}` : joined;
+}
+
+/** `\\server\share` or `//server/share` when both names are real path segments. */
+function uncSharePrefix(
+  path: string,
+): { readonly prefix: string; readonly separator: "/" | "\\" } | null {
+  if (!path.startsWith("//") && !path.startsWith("\\\\")) return null;
+  const body = path.slice(2);
+  const serverEnd = body.search(/[\\/]/);
+  if (serverEnd <= 0) return null;
+  const server = body.slice(0, serverEnd);
+  const afterServer = body.slice(serverEnd + 1);
+  const shareEnd = afterServer.search(/[\\/]/);
+  const share = shareEnd === -1 ? afterServer : afterServer.slice(0, shareEnd);
+  if (server === "." || server === ".." || share.length === 0 || share === "." || share === "..") {
+    return null;
+  }
+  return {
+    prefix: path.slice(0, 2 + server.length + 1 + share.length),
+    separator: body.charAt(serverEnd) as "/" | "\\",
+  };
+}