From af63b1e44aae239e61eaa2889537ff7017a74196 Mon Sep 17 00:00:00 2001
From: Lasmar Khalifa <lasmar.khalifa@shopify.com>
Date: Thu, 2 Jul 2026 11:43:13 -0400
Subject: [PATCH] add read tool formatters

---
 .../pi/messages/tool_call_message.rb          | 18 ++++++++++
 .../pi/messages/tool_result_message.rb        | 17 ++++++++++
 .../pi/messages/tool_call_message_test.rb     | 15 +++++++++
 .../pi/messages/tool_result_message_test.rb   | 33 +++++++++++++++++++
 4 files changed, 83 insertions(+)

diff --git a/lib/roast/cogs/agent/providers/pi/messages/tool_call_message.rb b/lib/roast/cogs/agent/providers/pi/messages/tool_call_message.rb
index d66c00fb..2f6088b1 100644
--- a/lib/roast/cogs/agent/providers/pi/messages/tool_call_message.rb
+++ b/lib/roast/cogs/agent/providers/pi/messages/tool_call_message.rb
@@ -61,6 +61,24 @@ def format_bash
                 command.empty? ? "BASH" : "BASH #{command}"
               end
 
+              # Formats a read tool call.
+              #
+              # Input fields:
+              #   :path (String) – file to read   [required]
+              #
+              # Output: "READ <path>", with :path truncated to TRUNCATE_LIMIT chars.
+              # A missing path renders the bare "READ".
+              #
+              # Examples:
+              #   READ lib/roast.rb
+              #   READ
+              #
+              #: () -> String
+              def format_read
+                path = truncate(arguments[:path])
+                path.empty? ? "READ" : "READ #{path}"
+              end
+
               # Formats a tool call for which Roast has no dedicated formatter.
               #
               # Output: "<NAME> <key>: <value>, ..." – the upcased tool name, then each
diff --git a/lib/roast/cogs/agent/providers/pi/messages/tool_result_message.rb b/lib/roast/cogs/agent/providers/pi/messages/tool_result_message.rb
index 05377281..adac0e26 100644
--- a/lib/roast/cogs/agent/providers/pi/messages/tool_result_message.rb
+++ b/lib/roast/cogs/agent/providers/pi/messages/tool_result_message.rb
@@ -74,6 +74,23 @@ def format_bash
                 ok_line("#{count} #{"line".pluralize(count)}", preview)
               end
 
+              # Formats a read tool result.
+              #
+              # Content: the file's text.
+              #
+              # Output: "READ OK <n> <line|lines>" – <n> is the line count (pluralized).
+              #
+              # Examples:
+              #   READ OK 42 lines
+              #   READ OK 1 line
+              #   READ OK 0 lines
+              #
+              #: () -> String
+              def format_read
+                count = content.to_s.lines.length
+                ok_line("#{count} #{"line".pluralize(count)}")
+              end
+
               # Formats a result for which Roast has no dedicated formatter.
               #
               # Content: the tool's output text.
diff --git a/test/roast/cogs/agent/providers/pi/messages/tool_call_message_test.rb b/test/roast/cogs/agent/providers/pi/messages/tool_call_message_test.rb
index 673f1c84..66de1343 100644
--- a/test/roast/cogs/agent/providers/pi/messages/tool_call_message_test.rb
+++ b/test/roast/cogs/agent/providers/pi/messages/tool_call_message_test.rb
@@ -26,6 +26,21 @@ class ToolCallMessageTest < ActiveSupport::TestCase
           assert_equal "BASH #{"x" * (ToolCallMessage::TRUNCATE_LIMIT - 3)}...", msg.format
         end
 
+        test "format renders READ with the path" do
+          msg = ToolCallMessage.new(id: "1", name: "read", arguments: { path: "lib/roast.rb" })
+          assert_equal "READ lib/roast.rb", msg.format
+        end
+
+        test "format renders a bare READ when the path is missing" do
+          msg = ToolCallMessage.new(id: "1", name: "read", arguments: {})
+          assert_equal "READ", msg.format
+        end
+
+        test "format truncates a long read path" do
+          msg = ToolCallMessage.new(id: "1", name: "read", arguments: { path: "x" * 100 })
+          assert_equal "READ #{"x" * (ToolCallMessage::TRUNCATE_LIMIT - 3)}...", msg.format
+        end
+
         test "format renders an unhandled tool as NAME key: value, ..." do
           msg = ToolCallMessage.new(
             id: "1",
diff --git a/test/roast/cogs/agent/providers/pi/messages/tool_result_message_test.rb b/test/roast/cogs/agent/providers/pi/messages/tool_result_message_test.rb
index 9635fc1e..24c92d0b 100644
--- a/test/roast/cogs/agent/providers/pi/messages/tool_result_message_test.rb
+++ b/test/roast/cogs/agent/providers/pi/messages/tool_result_message_test.rb
@@ -43,6 +43,39 @@ def setup
           assert_equal "BASH OK 0 lines", msg.format(@context)
         end
 
+        test "format summarizes read output with a line count" do
+          msg = ToolResultMessage.new(
+            tool_call_id: "1",
+            tool_name: "read",
+            content: "line one\nline two\nline three",
+            is_error: false,
+          )
+
+          assert_equal "READ OK 3 lines", msg.format(@context)
+        end
+
+        test "format pluralizes a single line of read output" do
+          msg = ToolResultMessage.new(
+            tool_call_id: "1",
+            tool_name: "read",
+            content: "just one line",
+            is_error: false,
+          )
+
+          assert_equal "READ OK 1 line", msg.format(@context)
+        end
+
+        test "format reports zero lines when the file is empty" do
+          msg = ToolResultMessage.new(
+            tool_call_id: "1",
+            tool_name: "read",
+            content: nil,
+            is_error: false,
+          )
+
+          assert_equal "READ OK 0 lines", msg.format(@context)
+        end
+
         test "format renders NAME ERROR with the message for an error result" do
           msg = ToolResultMessage.new(
             tool_call_id: "1",