IRC App: Alt scrolls, Up/Down recall sent lines; /j for /join

- Alt + ; / Alt + . scroll the Buffer back and forward
- Up / Down (Fn + ; / Fn + .) browse the last 30 sent lines, shell-style,
  returning to the draft past the newest (InputHistory, host-tested)
- /j is short for /join

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

lib/irc/src/irc_session.cpp

@@ -326,7 +326,7 @@ void IrcSession::command(int b, const std::string& text, int64_t utc) {
     const IrcBuffer& buf = buffers_[b];
     bool inChannel = buf.type == IrcBuffer::Type::Channel;
 
-    if (verb == "join") {
+    if (verb == "join" || verb == "j") {
         auto [channel, key] = firstWord(rest);
         if (channel.empty()) return info(b, "Usage: /join #channel", utc);
         if (!isChannel(channel)) channel = "#" + channel;
@@ -362,7 +362,7 @@ void IrcSession::command(int b, const std::string& text, int64_t utc) {
     } else if (verb == "raw" || verb == "quote") {
         if (!rest.empty()) send(rest);
     } else {
-        info(b, "Unknown command /" + verb + " (try /join /part /msg /me /nick /topic /names /quit /raw)", utc);
+        info(b, "Unknown command /" + verb + " (try /join or /j, /part /msg /me /nick /topic /names /quit /raw)", utc);
     }
 }
 

lib/ui/src/input_history.h

@@ -0,0 +1,50 @@
+#pragma once
+
+#include <deque>
+#include <string>
+
+namespace roro {
+
+// Lines already entered, browsed shell-style: up() goes back in time, down() forward, and past the
+// newest line the draft being typed comes back.
+class InputHistory {
+   public:
+    explicit InputHistory(size_t capacity) : capacity_(capacity) {}
+
+    void add(const std::string& line) {
+        browsing_ = -1;
+        if (line.empty() || (!lines_.empty() && lines_.back() == line)) return;
+        lines_.push_back(line);
+        if (lines_.size() > capacity_) lines_.pop_front();
+    }
+
+    // `current` is what the editor holds now (kept as the draft when browsing starts).
+    bool up(const std::string& current, std::string& out) {
+        if (lines_.empty() || browsing_ == 0) return false;
+        if (browsing_ < 0) {
+            draft_ = current;
+            browsing_ = static_cast<int>(lines_.size());
+        }
+        out = lines_[--browsing_];
+        return true;
+    }
+
+    bool down(std::string& out) {
+        if (browsing_ < 0) return false;
+        if (++browsing_ >= static_cast<int>(lines_.size())) {
+            browsing_ = -1;
+            out = draft_;
+        } else {
+            out = lines_[browsing_];
+        }
+        return true;
+    }
+
+   private:
+    size_t capacity_;
+    std::deque<std::string> lines_;
+    int browsing_ = -1;  // index being shown, -1 when editing the draft
+    std::string draft_;
+};
+
+}  // namespace roro