Dev

app/consts.ts

@@ -0,0 +1,4 @@
+// URL namespace under which the server serves local images.
+// The browser rewrites image srcs to this prefix (via pantsdown config)
+// and the server maps it back to filesystem paths relative to root.
+export const IMAGE_PREFIX = "/__github_preview__/image/";

app/github-preview.ts

@@ -68,6 +68,11 @@ export class GithubPreview {
          logging: { level: ENV.LOG_LEVEL === "none" ? undefined : ENV.LOG_LEVEL },
       });
 
+      nvim.onDisconnect(() => {
+         // neovim is gone, don't linger as an orphaned server process
+         process.exit(0);
+      });
+
       const props = (await nvim.call("nvim_get_var", ["github_preview_props"])) as PluginProps;
       if (ENV.IS_DEV) PluginPropsSchema.parse(props);
 
@@ -107,6 +112,9 @@ export class GithubPreview {
    }
 
    async getEntries(path: string): Promise<string[]> {
+      // do not return any entries outside of repo root
+      if (!normalize(this.root + path).startsWith(this.root)) return [];
+
       const currentDir = path.endsWith("/") ? path : dirname(path) + "/";
       const paths = await globby(currentDir + "*", {
          cwd: this.root,
@@ -134,7 +142,7 @@ export class GithubPreview {
    async setCurrPath(path: string): Promise<undefined | string[]> {
       // do not return any entries outside of repo root
       const normalized = normalize(this.root + path);
-      if (normalized.length < this.root.length) return;
+      if (!normalized.startsWith(this.root)) return;
 
       this.currentPath = path;
 

app/nvim/on-content-change.ts

@@ -1,3 +1,4 @@
+import { relative } from "node:path";
 import { type GithubPreview } from "../github-preview.ts";
 
 const NOTIFICATION = "attach_buffer";
@@ -15,19 +16,28 @@ export async function onContentChange(
       if (attachedBuffer === buffer) attachedBuffer = null;
    });
 
-   // Notification handler
-   app.nvim.onNotification(NOTIFICATION, async ([buffer, path]) => {
+   // Notification handler.
+   // Handled through a queue: rapid buffer switches could otherwise interleave
+   // across the awaits below and detach/attach the wrong buffer
+   let attachQueue = Promise.resolve();
+   app.nvim.onNotification(NOTIFICATION, ([buffer, path]) => {
       if (!path) return;
 
-      if (attachedBuffer !== buffer) {
-         if (attachedBuffer !== null) {
-            await app.nvim.call("nvim_buf_detach", [attachedBuffer]);
-            attachedBuffer = null;
-         }
-         // attach to buffer to receive content change notifications
-         const attached = await app.nvim.call("nvim_buf_attach", [buffer, true, {}]);
-         if (attached) attachedBuffer = buffer;
-      }
+      attachQueue = attachQueue
+         .then(async () => {
+            if (attachedBuffer === buffer) return;
+
+            if (attachedBuffer !== null) {
+               await app.nvim.call("nvim_buf_detach", [attachedBuffer]);
+               attachedBuffer = null;
+            }
+            // attach to buffer to receive content change notifications
+            const attached = await app.nvim.call("nvim_buf_attach", [buffer, true, {}]);
+            if (attached) attachedBuffer = buffer;
+         })
+         .catch((err: unknown) => {
+            app.nvim.logger?.error({ attach_buffer_error: err });
+         });
    });
 
    // Create autocmd to notify us with event "attach_buffer"
@@ -53,10 +63,19 @@ export async function onContentChange(
       async ([buffer, _changedtick, firstline, lastline, linedata, _more]) => {
          const path = await app.nvim.call("nvim_buf_get_name", [buffer]);
          const replaceAll = lastline === -1 && firstline === 0;
-         const deleteCount = lastline - firstline;
-         const newContent = replaceAll
-            ? linedata
-            : app.lines.toSpliced(firstline, deleteCount, ...linedata);
+
+         let newContent: string[];
+         if (replaceAll) {
+            newContent = linedata;
+         } else if (relative(app.root, path) === app.currentPath) {
+            const deleteCount = lastline - firstline;
+            newContent = app.lines.toSpliced(firstline, deleteCount, ...linedata);
+         } else {
+            // app.lines mirrors a different file (e.g. browser navigated away),
+            // an incremental splice would corrupt it. Fetch the full buffer instead.
+            newContent = await app.nvim.call("nvim_buf_get_lines", [buffer, 0, -1, true]);
+         }
+
          callback(newContent, path);
       },
    );

app/server/index.ts

@@ -1,5 +1,7 @@
+import { normalize } from "node:path";
 import { type Server } from "bun";
 import opener from "opener";
+import { IMAGE_PREFIX } from "../consts.ts";
 import { type GithubPreview } from "../github-preview.ts";
 import index from "../web/index.html";
 import { websocketHandler } from "./websocket.ts";
@@ -12,13 +14,23 @@ export function startServer<T>(app: GithubPreview, isDev: boolean): Server<T> {
    const server = Bun.serve({
       port: port,
       routes: {
-         "/__github_preview__/image/*": (req) => {
+         [IMAGE_PREFIX + "*"]: (req: Request) => {
             app.nvim.logger?.info({ route: req.url });
             const pathname = new URL(req.url).pathname;
-            const filePath = pathname.replace("/__github_preview__/image/", "");
-            app.nvim.logger?.info({ filePath: app.root + filePath });
+            let filePath: string;
+            try {
+               filePath = decodeURIComponent(pathname.replace(IMAGE_PREFIX, ""));
+            } catch (_err) {
+               return new Response(null, { status: 400 });
+            }
+            // do not serve any files outside of repo root
+            const fullPath = normalize(app.root + filePath);
+            if (!fullPath.startsWith(app.root)) {
+               return new Response(null, { status: 404 });
+            }
+            app.nvim.logger?.info({ filePath: fullPath });
             // images with relative sources
-            const file = Bun.file(app.root + filePath);
+            const file = Bun.file(fullPath);
             return new Response(file);
          },
          [UNALIVE_URL]: async (req) => {

app/web/components/markdown/index.tsx

@@ -1,5 +1,6 @@
 import { Pantsdown } from "pantsdown";
 import { useContext, useEffect, useState } from "react";
+import { IMAGE_PREFIX } from "../../../consts.ts";
 import { cn, getFileExt } from "../../utils.ts";
 import { websocketContext } from "../websocket-provider/context.ts";
 import { BreadCrumbs } from "./breadcrumbs.tsx";
@@ -13,8 +14,6 @@ import { getScrollOffsets, type Offsets } from "./scroll.ts";
 const MARKDOWN_CONTAINER_ID = "markdown-container-id";
 const MARKDOWN_ELEMENT_ID = "markdown-element-id";
 
-const IMAGE_PREFIX = "/__github_preview__/image/";
-
 const pantsdown = new Pantsdown({
    renderer: {
       relativeImageUrlPrefix: IMAGE_PREFIX,

lua/github-preview/functions.lua

@@ -39,12 +39,18 @@ M.start = function()
 		return
 	end
 
-	-- should look like "/Users/.../github-preview"
-	local root = Config.value.single_file and "" or vim.fn.finddir(".git", ";")
+	-- single-file mode may also be enabled as a fallback when no repo is found.
+	-- keep it local so the fallback doesn't stick to Config.value across starts
+	local single_file = Config.value.single_file
 
 	local buffer_name = vim.api.nvim_buf_get_name(0)
 	local init_path = vim.fn.fnamemodify(buffer_name, ":p")
 
+	-- search for ".git" upwards starting from the current file's directory,
+	-- not from cwd: the file being edited may live outside of nvim's cwd.
+	-- should look like "/Users/.../github-preview/.git"
+	local root = single_file and "" or vim.fn.finddir(".git", vim.fn.fnamemodify(init_path, ":h") .. ";")
+
 	if root == "" then
 		-- if repo root not found or single-file mode is enabled,
 		-- we make sure there's something loaded into the current buffer
@@ -58,7 +64,7 @@ M.start = function()
 
 		-- if no root, we set root to current path
 		root = vim.fn.fnamemodify(init_path, ":h") .. "/"
-		Config.value.single_file = true
+		single_file = true
 	else
 		-- if found, path is made absolute & has "/.git/" popped
 		root = vim.fn.fnamemodify(root, ":p:h:h") .. "/"
@@ -70,7 +76,7 @@ M.start = function()
 			root = root,
 			path = init_path,
 		},
-		config = Config.value,
+		config = vim.tbl_deep_extend("force", Config.value, { single_file = single_file }),
 	}
 	-- vim.g.github_preview_props is read by bunvim
 	vim.g.github_preview_props = github_preview_props

package.json

@@ -22,13 +22,13 @@
   },
   "dependencies": {
     "bun-plugin-tailwind": "^0.1.2",
-    "bunvim": "1.2.0",
+    "bunvim": "1.3.0",
     "clsx": "^2.1.1",
     "globby": "^16.2.2",
     "isbinaryfile": "6.0.0",
     "mermaid": "^11.16.0",
     "opener": "^1.5.2",
-    "pantsdown": "2.2.6",
+    "pantsdown": "2.2.7",
     "react": "^19.2.7",
     "react-dom": "^19.2.7",
     "reconnecting-websocket": "^4.4.0",