feat: make Research tabs closable and preserve workspace navigation

README.md

@@ -40,8 +40,7 @@ See [execution support](docs/execution-support.md) and the
 
 Reader search and article selection, Messages views and conversations, Home
 previews, account management, Journal review/correction views, and Vitals
-navigation are represented in search parameters. Research uses deck, run, and
-citation IDs. Reloading or browser Back/Forward restores the view while its
+navigation are represented in search parameters. Research uses deck, run, citation IDs, and closed-tab IDs. Reloading or browser Back/Forward restores the view while its
 underlying data remains available. Login preserves the requested workspace URL.
 
 Explicit selections add browser history; search input replaces it after a
@@ -201,7 +200,7 @@ available. The backend handles tools even when the browser is closed.
 Use **New chat** to leave the current conversation and start a fresh Codex
 thread with your next message. The open deck and host reports remain available.
 A running turn continues in the background when you open another chat.
-Selection belongs to the current URL; another browser does not change it. **Chat history** appears as a horizontally scrollable tab strip above the chat and deck, with a **+** button for a new chat. Tabs reopen saved conversations with their account
+Selection belongs to the current URL; another browser does not change it. **Chat history** appears as a horizontally scrollable tab strip above the chat and deck, to the right of the workspace navigation. Use **+** for a new chat or **×** to close a tab. Closing a tab keeps its conversation and running research; the history menu reopens it. Tab clicks have no animation. Tabs reopen saved conversations with their account
 selection, deck and citations; the next message resumes the same Codex thread.
 SQLite stores conversation snapshots. Active selection is not stored globally.
 Each turn is limited to 6 columns, 12 upstream requests shared between list