put the soulseek room and chat peer in the url

The last two selections in Soulseek still held in useState. `?room=` and
`?peer=` now own them, the rails are links, and the leave/close buttons stay
siblings of the anchor.

Both rails auto-selected the first entry on load, which is the reason the
selection was local: there was nowhere to put an answer the user had not given.
The bare section is a real state now — nothing open — and both panels already
had the empty pane to say so. Rooms' pane said "Join a room to start chatting"
unconditionally, which was wrong once you could be joined to rooms with none
open, so it now distinguishes the two.

Join and "message a user" stay buttons: each writes something and *then* opens
it, which a link cannot express.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/workspaces/officerdev/src/apps/Soulseek/SoulseekChat.tsx

@@ -1,8 +1,9 @@
 import { useState, useEffect, useRef, useCallback } from 'react';
+import { Link, useSearchParams } from 'react-router';
 import { useClient } from 'hooks/useClient';
 import { toast } from 'sonner';
 import { MessageCircle, Send, Plus, RefreshCw, X } from 'lucide-react';
-import { formatClock, type SlskdConversation, type SlskdPrivateMessage } from './shared';
+import { formatClock, soulseekPeerPath, PEER_PARAM, type SlskdConversation, type SlskdPrivateMessage } from './shared';
 
 // Chat panel — private (1:1) messaging. GET /conversations lists the peers we have threads with; GET
 // /conversations/{user}/messages returns a thread (polled while it's open). Sending POSTs a bare JSON
@@ -16,8 +17,9 @@ const isMine = (m: SlskdPrivateMessage) => (m.direction ?? '').toLowerCase() ===
 
 export const SoulseekChat = () => {
   const client = useClient();
+  const [params, setParams] = useSearchParams();
+  const selected = params.get(PEER_PARAM)?.trim() || null;
   const [conversations, setConversations] = useState<SlskdConversation[]>([]);
-  const [selected, setSelected] = useState<string | null>(null);
   const [messages, setMessages] = useState<SlskdPrivateMessage[]>([]);
   const [draft, setDraft] = useState('');
   const [peerName, setPeerName] = useState('');
@@ -25,9 +27,7 @@ export const SoulseekChat = () => {
 
   const loadConversations = useCallback(async () => {
     try {
-      const list = await client.get<SlskdConversation[]>('/slskd/api/v0/conversations');
-      setConversations(list);
-      setSelected((cur) => cur ?? list[0]?.username ?? null);
+      setConversations(await client.get<SlskdConversation[]>('/slskd/api/v0/conversations'));
     } catch {
       /* status panel surfaces connection errors */
     }
@@ -73,12 +73,18 @@ export const SoulseekChat = () => {
     if (el) el.scrollTop = el.scrollHeight;
   }, [messages.length, selected]);
 
+  // Starts a thread that isn't in the list yet, so it stays a form submit rather than a link: it adds the
+  // peer locally *and then* opens it, and a link cannot express the "and then".
   const openPeer = (name: string) => {
     const target = name.trim();
     if (!target) return;
     setPeerName('');
-    setSelected(target);
     setConversations((prev) => (prev.some((c) => c.username === target) ? prev : [...prev, { username: target }]));
+    setParams((prev) => {
+      const next = new URLSearchParams(prev);
+      next.set(PEER_PARAM, target);
+      return next;
+    });
   };
 
   const close = async (name: string) => {
@@ -87,11 +93,19 @@ export const SoulseekChat = () => {
     } catch {
       /* optimistic — drop it locally regardless */
     }
-    setConversations((prev) => {
-      const next = prev.filter((c) => c.username !== name);
-      setSelected((cur) => (cur === name ? next[0]?.username ?? null : cur));
-      return next;
-    });
+    setConversations((prev) => prev.filter((c) => c.username !== name));
+    // Closing the open thread leaves nothing open. `replace`, because the thread you just deleted is not
+    // somewhere Back should return you to.
+    if (name === selected) {
+      setParams(
+        (prev) => {
+          const next = new URLSearchParams(prev);
+          next.delete(PEER_PARAM);
+          return next;
+        },
+        { replace: true },
+      );
+    }
   };
 
   const send = async () => {
@@ -130,14 +144,15 @@ export const SoulseekChat = () => {
                   active ? 'bg-primary/10 text-primary' : 'text-muted-foreground hover:bg-muted hover:text-foreground'
                 }`}
               >
-                <button
-                  type="button"
-                  onClick={() => setSelected(c.username)}
+                {/* The close button is a sibling, never nested inside the anchor. */}
+                <Link
+                  to={soulseekPeerPath(c.username)}
                   className="flex min-w-0 flex-1 items-center gap-1.5 text-left"
+                  aria-current={active ? 'true' : undefined}
                 >
                   <MessageCircle className="h-3.5 w-3.5 shrink-0" />
                   <span className="truncate">{c.username}</span>
-                </button>
+                </Link>
                 {unread > 0 && !active && (
                   <span className="shrink-0 rounded-full bg-primary px-1.5 text-[10px] font-medium tabular-nums text-primary-foreground">
                     {unread}

src/workspaces/officerdev/src/apps/Soulseek/SoulseekRooms.tsx

@@ -1,8 +1,9 @@
 import { useState, useEffect, useRef, useMemo, useCallback } from 'react';
+import { Link, useSearchParams } from 'react-router';
 import { useClient } from 'hooks/useClient';
 import { toast } from 'sonner';
 import { Hash, Users, LogOut, Send, Plus, RefreshCw } from 'lucide-react';
-import { formatClock, type SlskdRoom, type SlskdRoomInfo } from './shared';
+import { formatClock, soulseekRoomPath, ROOM_PARAM, type SlskdRoom, type SlskdRoomInfo } from './shared';
 
 // Rooms panel — join Soulseek chat rooms and talk in them. GET /rooms/joined lists the room names we're
 // in; GET /rooms/joined/{name} inlines that room's users + messages (polled while it's open); GET
@@ -17,7 +18,8 @@ export const SoulseekRooms = () => {
   const client = useClient();
   const [joined, setJoined] = useState<string[]>([]);
   const [available, setAvailable] = useState<SlskdRoomInfo[]>([]);
-  const [selected, setSelected] = useState<string | null>(null);
+  const [params, setParams] = useSearchParams();
+  const selected = params.get(ROOM_PARAM)?.trim() || null;
   const [room, setRoom] = useState<SlskdRoom | null>(null);
   const [draft, setDraft] = useState('');
   const [joinName, setJoinName] = useState('');
@@ -26,9 +28,7 @@ export const SoulseekRooms = () => {
 
   const loadJoined = useCallback(async () => {
     try {
-      const names = await client.get<string[]>('/slskd/api/v0/rooms/joined');
-      setJoined(names);
-      setSelected((cur) => cur ?? names[0] ?? null);
+      setJoined(await client.get<string[]>('/slskd/api/v0/rooms/joined'));
     } catch {
       /* status panel surfaces connection errors */
     }
@@ -95,7 +95,12 @@ export const SoulseekRooms = () => {
       await client.post('/slskd/api/v0/rooms/joined', target);
       setJoinName('');
       setJoined((prev) => (prev.includes(target) ? prev : [...prev, target]));
-      setSelected(target);
+      // Joins the room *and then* opens it, so this stays a button — a link cannot express the "and then".
+      setParams((prev) => {
+        const next = new URLSearchParams(prev);
+        next.set(ROOM_PARAM, target);
+        return next;
+      });
       toast.success(`Joined ${target}`);
     } catch (err) {
       toast.error(`Couldn't join ${target}: ${err instanceof Error ? err.message : String(err)}`);
@@ -107,11 +112,19 @@ export const SoulseekRooms = () => {
   const leave = async (name: string) => {
     try {
       await client.delete(`/slskd/api/v0/rooms/joined/${encodeURIComponent(name)}`);
-      setJoined((prev) => {
-        const next = prev.filter((n) => n !== name);
-        setSelected((cur) => (cur === name ? next[0] ?? null : cur));
-        return next;
-      });
+      setJoined((prev) => prev.filter((n) => n !== name));
+      // Leaving the open room leaves nothing open. `replace`, because a room you are no longer in is not
+      // somewhere Back should return you to.
+      if (name === selected) {
+        setParams(
+          (prev) => {
+            const next = new URLSearchParams(prev);
+            next.delete(ROOM_PARAM);
+            return next;
+          },
+          { replace: true },
+        );
+      }
     } catch (err) {
       toast.error(`Couldn't leave ${name}: ${err instanceof Error ? err.message : String(err)}`);
     }
@@ -150,10 +163,15 @@ export const SoulseekRooms = () => {
                   active ? 'bg-primary/10 text-primary' : 'text-muted-foreground hover:bg-muted hover:text-foreground'
                 }`}
               >
-                <button type="button" onClick={() => setSelected(name)} className="flex min-w-0 flex-1 items-center gap-1.5 text-left">
+                {/* The leave button is a sibling, never nested inside the anchor. */}
+                <Link
+                  to={soulseekRoomPath(name)}
+                  className="flex min-w-0 flex-1 items-center gap-1.5 text-left"
+                  aria-current={active ? 'true' : undefined}
+                >
                   <Hash className="h-3.5 w-3.5 shrink-0" />
                   <span className="truncate">{name}</span>
-                </button>
+                </Link>
                 <button
                   type="button"
                   onClick={() => leave(name)}
@@ -207,7 +225,9 @@ export const SoulseekRooms = () => {
         {!selected ? (
           <div className="flex flex-1 flex-col items-center justify-center gap-2 text-center text-muted-foreground">
             <Hash className="h-8 w-8" />
-            <p className="text-sm">Join a room to start chatting.</p>
+            <p className="text-sm">
+              {joined.length === 0 ? 'Join a room to start chatting.' : 'Pick a room to read it.'}
+            </p>
           </div>
         ) : (
           <>

src/workspaces/officerdev/src/apps/Soulseek/shared.ts

@@ -288,6 +288,23 @@ export const USER_PARAM = 'user';
 export const soulseekUserPath = (username: string) =>
   `${soulseekSectionPath('users')}?${USER_PARAM}=${encodeURIComponent(username)}`;
 
+// Which room the Rooms section is showing — `/soulseek/rooms?room=<name>` — and which thread the Chat
+// section is showing — `/soulseek/chat?peer=<name>`. Two params rather than one because they are two
+// sections: they never appear together, and a shared name would make `?thing=` mean different kinds of
+// thing depending on the path.
+//
+// Both rails used to auto-select the first entry on load, which is why they held the selection locally:
+// there was nowhere else to put an answer the user had not given. The bare section is now a real state —
+// "nothing open" — and both panels already had the empty pane to say so.
+export const ROOM_PARAM = 'room';
+export const PEER_PARAM = 'peer';
+
+export const soulseekRoomPath = (name: string) =>
+  `${soulseekSectionPath('rooms')}?${ROOM_PARAM}=${encodeURIComponent(name)}`;
+
+export const soulseekPeerPath = (username: string) =>
+  `${soulseekSectionPath('chat')}?${PEER_PARAM}=${encodeURIComponent(username)}`;
+
 // A past search, as listed by GET /searches (no responses inlined).
 // Which search's results are open — `/soulseek/search?search=<id>`, read from the URL rather than held in a
 // panel channel or local state. See docs/navigation-audit.md.