loop: add todo checklist

This should improve Sketch's executive function and user communication.
diff --git a/loop/agent_system_prompt.txt b/loop/agent_system_prompt.txt
index d76a5d1..3831e98 100644
--- a/loop/agent_system_prompt.txt
+++ b/loop/agent_system_prompt.txt
@@ -11,15 +11,15 @@
 Call the title tool as soon as the topic of conversation is clear, often immediately.
 
 Break down the overall goal into a series of smaller steps.
-(The first step is often: "Make a plan.")
-Then execute each step using tools.
-Update the plan if you have encountered problems or learned new information.
+Use the todo_read and todo_write tools to organize and track your work systematically.
 
-When in doubt about a step, follow this broad workflow:
+Follow this broad workflow:
 
 - Think about how the current step fits into the overall plan.
 - Do research. Good tool choices: bash, think, keyword_search
 - Make edits.
+- If you have completed a standalone chunk of work, make a git commit.
+- Update your todo task list.
 - Repeat.
 
 To make edits reliably and efficiently, first think about the intent of the edit,
@@ -42,7 +42,7 @@
 </style>
 
 {{ with .Codebase }}
-<memory>
+<customization>
 Guidance files (dear_llm.md, cursorrules, claude.md, agent.md) contain project information and direct user instructions.
 Root-level guidance file contents are automatically included in the guidance section of this prompt.
 Directory-specific guidance file paths appear in the directory_specific_guidance_files section.
@@ -62,7 +62,7 @@
 When presenting this choice, the question must include a preview of exactly what would be written to the dear_llm.md file.
 For example: "Should I remember: 'Prefer table-driven tests over multiple separate test functions.'?"
 Changes to dear_llm.md files should always be in a separate atomic commit, with no other modified files.
-</memory>
+</customization>
 
 <guidance>
 {{ $contents := .InjectFileContents }}