Allow stashing of redirected URLs

If the user unstashes and then re-stashes a privileged URL, the internal
Tab Stash redirection page might get saved instead of the actual URL the
user wants.  Check for and explicitly allow (re-)stashing of redirection
pages, and save the original URL instead.

This has the added benefit that we don't put Tab Stash-specific
droppings in the user's bookmarks, either.

src/model/index.ts

@@ -42,6 +42,7 @@ import {
   textMatcher,
   tryAgain,
   urlToOpen,
+  urlToStash,
 } from "../util";
 import {trace_fn} from "../util/debug";
 import {logError, logErrorsFrom, UserError} from "../util/oops";
@@ -282,8 +283,8 @@ export class Model {
       return false;
     }
 
-    // Tab Stash URLs are never stashable.
-    return !url_str.startsWith(browser.runtime.getURL(""));
+    // The Tab Stash UI is never stashable.
+    return !url_str.startsWith(browser.runtime.getURL("stash-list.html"));
   }
 
   /** If the topmost folder in the stash root is an unnamed folder which was
@@ -692,7 +693,7 @@ export class Model {
             "url" in item
               ? await this.bookmarks.create({
                   title: item.title || item.url,
-                  url: item.url,
+                  url: urlToStash(item.url),
                   parentId,
                   index,
                 })

src/util/index.ts

@@ -161,6 +161,17 @@ export function urlToOpen(urlstr: string): OpenableURL {
   }
 }
 
+/** Does the inverse of urlToOpen() -- turns a possibly-redirected URL back into
+ * its original form. */
+export function urlToStash(url: string | OpenableURL): string {
+  if (url.startsWith(REDIR_PAGE + "?")) {
+    const redirUrl = new URL(url);
+    const origUrl = redirUrl.searchParams.get("url");
+    if (origUrl) return origUrl;
+  }
+  return url;
+}
+
 function redirUrl(url: string): OpenableURL {
   return `${REDIR_PAGE}?url=${encodeURIComponent(url)}` as OpenableURL;
 }