Add quick review button.

assets/icons/icons.gresource.xml

@@ -7,6 +7,7 @@
 -->
 <gresources>
   <gresource prefix="/dev/greyson/playpen/icons">
+    <file compressed="true">scalable/actions/chat-message-new-symbolic.svg</file>
     <file compressed="true">scalable/actions/document-edit-symbolic.svg</file>
     <file compressed="true">scalable/actions/edit-undo-symbolic.svg</file>
     <file compressed="true">scalable/actions/emblem-system-symbolic.svg</file>

assets/icons/scalable/actions/chat-message-new-symbolic.svg

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg height="16px" viewBox="0 0 16 16" width="16px" xmlns="http://www.w3.org/2000/svg">
+    <path d="m 3 1 c -1.644531 0 -3 1.355469 -3 3 v 6 c 0 1.644531 1.355469 3 3 3 h 1 v 3 l 3 -3 v -1 c 0 -0.550781 -0.449219 -1 -1 -1 h -3 c -0.570312 0 -1 -0.429688 -1 -1 v -6 c 0 -0.554688 0.445312 -1 1 -1 h 10 c 0.554688 0 1 0.445312 1 1 v 4 c 0 0.550781 0.449219 1 1 1 s 1 -0.449219 1 -1 v -4 c 0 -1.644531 -1.355469 -3 -3 -3 z m 8 7 v 3 h -3 v 2 h 3 v 3 h 2 v -3 h 3 v -2 h -3 v -3 z m 0 0" fill="#2e3436"/>
+</svg>

src/Pane.zig

@@ -506,6 +506,13 @@ fn buildHeader(self: *Pane) void {
     _ = gtk.Button.signals.clicked.connect(review_button, *Pane, &onReviewClicked, self, .{});
     header.append(review_button.as(gtk.Widget));
 
+    const agent_review = gtk.Button.newFromIconName("chat-message-new-symbolic");
+    agent_review.as(gtk.Widget).addCssClass("flat");
+    agent_review.as(gtk.Widget).addCssClass("playpen-pane-button");
+    agent_review.as(gtk.Widget).setTooltipText("Have Claude review this tab's changes in the review pane");
+    _ = gtk.Button.signals.clicked.connect(agent_review, *Pane, &onAgentReviewClicked, self, .{});
+    header.append(agent_review.as(gtk.Widget));
+
     // Last before close, so the destructive button stays on the end where it
     // is expected and the zoom toggle sits with the other view controls.
     self.zoom.as(gtk.Widget).addCssClass("flat");
@@ -765,6 +772,10 @@ fn onReviewClicked(_: *gtk.Button, self: *Pane) callconv(.c) void {
     self.view.requestReview();
 }
 
+fn onAgentReviewClicked(_: *gtk.Button, self: *Pane) callconv(.c) void {
+    self.view.startAgentReview(self);
+}
+
 fn onZoomClicked(_: *gtk.Button, self: *Pane) callconv(.c) void {
     self.view.toggleZoom(self);
 }

src/View.zig

@@ -355,6 +355,56 @@ pub fn requestReview(self: *View) void {
     self.on_review(self.ctx);
 }
 
+/// What the pane header's agent-review button types into the new shell.
+const agent_review_command = "claude '/pr-review using /leave-review'";
+
+/// Open a Claude Code session beside `from`, in the directory `from` is working
+/// in, and have it review the tab's diff into the review pane.
+///
+/// `/leave-review` posts to this tab's review pane and stops if there isn't
+/// one, so a missing pane is opened first rather than leaving the session to
+/// fail on arrival. `from` is focused before that, so the review is bound to
+/// the same directory the session starts in.
+pub fn startAgentReview(self: *View, from: *Pane) void {
+    var buf: [std.fs.max_path_bytes]u8 = undefined;
+    const cwd = self.paneDirectory(from, &buf);
+
+    if (self.reviewPane() == null) {
+        self.setFocused(from);
+        self.requestReview();
+    }
+
+    self.addPane(.{ .terminal = .{
+        .cwd = cwd,
+        .command = agent_review_command,
+    } }) catch |err| {
+        std.log.err("failed to open the agent review: {s}", .{@errorName(err)});
+    };
+}
+
+/// The directory `pane` is working in, copied into `buf`, or empty to leave it
+/// to the shell's default.
+///
+/// A terminal answers for itself, a review pane with the repository it is bound
+/// to; a web pane has no directory, so it borrows the first terminal's in the
+/// tab.
+fn paneDirectory(self: *View, pane: *Pane, buf: []u8) []const u8 {
+    switch (pane.content) {
+        .terminal => |t| if (t.session.cwd(buf)) |dir| return dir,
+        .review => if (self.review_spec.repo.len > 0) {
+            const n = @min(buf.len, self.review_spec.repo.len);
+            @memcpy(buf[0..n], self.review_spec.repo[0..n]);
+            return buf[0..n];
+        },
+        .web => {},
+    }
+    for (self.panes.items) |other| {
+        const t = other.terminal() orelse continue;
+        if (t.session.cwd(buf)) |dir| return dir;
+    }
+    return "";
+}
+
 pub fn closePane(self: *View, pane: *Pane) void {
     if (self.closing) return;