From 58caf9faf780bc61d5744d9f3d7bb79d0cf148c3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Adri=C3=A0=20Arrufat?= <adria.arrufat@gmail.com>
Date: Sat, 30 May 2026 23:12:54 +0200
Subject: [PATCH] agent: pretty-print JSON command results

Re-indents JSON output with 2-space indentation for better readability
in the terminal, while keeping non-JSON output unchanged.
---
 src/agent/Agent.zig | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/src/agent/Agent.zig b/src/agent/Agent.zig
index f37a45fe..40524f4a 100644
--- a/src/agent/Agent.zig
+++ b/src/agent/Agent.zig
@@ -901,12 +901,29 @@ fn printCommandResult(self: *Agent, cmd: Command, result: browser_tools.ToolResu
         else => return,
     };
     if (cmd.producesData() and !result.is_error) {
-        self.terminal.printAssistant(result.text);
+        self.printData(result.text);
         return;
     }
     self.terminal.printToolOutcome(tc.name(), result.text, result.is_error);
 }
 
+// REPL-only: re-indent JSON output for the terminal. MCP keeps renderJson's
+// compact form. Non-JSON output (markdown, tree, urls) prints unchanged.
+fn printData(self: *Agent, text: []const u8) void {
+    const trimmed = std.mem.trimLeft(u8, text, &std.ascii.whitespace);
+    if (trimmed.len > 0 and (trimmed[0] == '{' or trimmed[0] == '[')) {
+        if (std.json.parseFromSlice(std.json.Value, self.allocator, text, .{})) |parsed| {
+            defer parsed.deinit();
+            if (std.json.Stringify.valueAlloc(self.allocator, parsed.value, .{ .whitespace = .indent_2 })) |pretty| {
+                defer self.allocator.free(pretty);
+                self.terminal.printAssistant(pretty);
+                return;
+            } else |_| {}
+        } else |_| {}
+    }
+    self.terminal.printAssistant(text);
+}
+
 fn runScript(self: *Agent, path: []const u8) bool {
     self.terminal.printInfo("Running script: {s}", .{path});