add task tool use formatter

lib/roast/cogs/agent/providers/claude/tool_use.rb

@@ -237,6 +237,35 @@ def format_skill
               args ? "SKILL #{skill} (#{truncate(args)})" : "SKILL #{skill}"
             end
 
+            # Formats a Task tool-use line.
+            #
+            # Input fields:
+            #   :description       (String) – short label for the task       [required]
+            #   :run_in_background (bool)   – run the agent asynchronously    [optional]
+            #   :subagent_type     (String) – which agent type to spawn       [optional]
+            #   :model             (String) – model override for the agent    [optional]
+            #
+            # Output: "TASK <description>", with " (<details>)" appended when any
+            # optional field is set: "background" (when :run_in_background is set),
+            # then :subagent_type, then :model — joined with " · " in that order and
+            # shown as raw values (no key= labels). :description is truncated to
+            # TRUNCATE_LIMIT chars; the other fields are not.
+            #
+            # Examples:
+            #   TASK Find all callers (background · Explore · opus)
+            #   TASK Summarize the diff
+            #
+            #: () -> String
+            def format_task
+              description = truncate(input[:description])
+              details = [
+                ("background" if input[:run_in_background]),
+                input[:subagent_type],
+                input[:model],
+              ].compact.join(" · ")
+              details.empty? ? "TASK #{description}" : "TASK #{description} (#{details})"
+            end
+
             #: () -> String
             def format_unknown
               "UNKNOWN [#{name}] #{input.inspect}"

test/roast/cogs/agent/providers/claude/tool_use_test.rb

@@ -300,6 +300,44 @@ class ToolUseTest < ActiveSupport::TestCase
               assert_equal "SKILL #{long} (#{truncated})", output
             end
 
+            # format_task
+
+            test "format_task renders the description alone with no optional fields" do
+              tool_use = ToolUse.new(name: :task, input: { description: "Find all callers" })
+
+              output = tool_use.format
+
+              assert_equal "TASK Find all callers", output
+            end
+
+            test "format_task joins background, subagent type, and model in order" do
+              input = { description: "Audit", run_in_background: true, subagent_type: "Explore", model: "opus" }
+              tool_use = ToolUse.new(name: :task, input: input)
+
+              output = tool_use.format
+
+              assert_equal "TASK Audit (background · Explore · opus)", output
+            end
+
+            test "format_task omits background when run_in_background is false" do
+              tool_use = ToolUse.new(name: :task, input: { description: "Audit", run_in_background: false })
+
+              output = tool_use.format
+
+              assert_equal "TASK Audit", output
+            end
+
+            test "format_task truncates the description but not the subagent type or model" do
+              long = "a" * (ToolUse::TRUNCATE_LIMIT + 10)
+              truncated = "#{"a" * (ToolUse::TRUNCATE_LIMIT - 3)}..."
+              input = { description: long, subagent_type: long, model: long }
+              tool_use = ToolUse.new(name: :task, input: input)
+
+              output = tool_use.format
+
+              assert_equal "TASK #{truncated} (#{long} · #{long})", output
+            end
+
             test "format calls format_unknown for unknown tool" do
               tool_use = ToolUse.new(name: :unknown_tool, input: { arg: "value" })