New /summarize cmd compacts into a SUMMARY-* file.

aider/commands.py

@@ -1559,6 +1559,26 @@ def cmd_edit(self, args=""):
         "Alias for /editor: Open an editor to write a prompt"
         return self.cmd_editor(args)
 
+    def cmd_summarize(self, args):
+        "Create a technical summary of the chat and work done so far"
+        from datetime import datetime
+
+        filename = args.strip()
+        today = datetime.now().strftime("%Y-%m-%d")
+
+        if filename:
+            file_instruction = f"Save this summary into `{filename}`."
+        else:
+            file_instruction = (
+                "Save this summary into a new Markdown file named "
+                f"`SUMMARY-{today}-description.md`, replacing 'description' "
+                "with a 3-5 word slug representing our task."
+            )
+
+        prompt = prompts.summarize_command_prompt.format(file_instruction=file_instruction).strip()
+
+        return self._generic_chat_command(prompt, self.coder.main_model.edit_format)
+
     def cmd_think_tokens(self, args):
         """Set the thinking token budget, eg: 8096, 8k, 10.5k, 0.5M, or 0 to disable."""
         model = self.coder.main_model

aider/prompts.py

@@ -59,3 +59,17 @@
 """
 
 summary_prefix = "I spoke to you previously about a number of things.\n"
+
+# /summarize
+summarize_command_prompt = """
+Act as a senior software engineer. Create a detailed technical summary of our entire conversation and the work performed so far. {file_instruction}
+
+The summary must include:
+1. **Project Context**: The high-level goal of the current session.
+2. **Work Completed**: Specific changes made, including key functions or files modified.
+3. **Technical Discoveries**: Non-obvious insights gained about the codebase, logic constraints, or bugs identified during development.
+4. **Architectural Decisions**: Why specific approaches were taken over alternatives.
+5. **Pending Work**: A 'Next Steps' section with enough detail for a developer to resume immediately.
+
+Preserve all critical technical details and specific implementation patterns discussed. Write the output as a Markdown file.
+"""