Get an architecture map of an unfamiliar codebase in one prompt
Feed a whole repository into a long-context model and get a markdown overview of what each file does and which libraries it relies on.
Oct 25, 2026
Here is the full source of a repository. Write a markdown architecture overview: 1) purpose of the project, 2) a table of main files or folders and what each does, 3) key libraries and why they are used, 4) how a request or command flows through the code. Flag anything you are unsure about. [paste repo bundle]
How to use it
1. Clone the repository locally 2. Bundle the source files into one text file (for example with a files-to-prompt style script) 3. Paste or upload the bundle into a long-context model such as Gemini 4. Ask for an architectural overview in markdown 5. Ask follow-up questions about specific modules 6. Verify key claims by opening the referenced files
Result
Got a markdown overview of which files do what and which libraries are used; used several times a week. Example: Input: 40 files of a CLI tool. Output: a one-page overview with a file table, a dependency list and a request-flow section.
Tips and gotchas
Human review: Treat as a starting map; verify against code. Pitfall: Low stakes but can be wrong; needs long-context model. Privacy: Do not paste proprietary code into tools your company has not approved. Best for: Developers, technical leads (Intermediate). Time saved basis: Estimate.
simonwillison.net
https://simonwillison.net/2025/Mar/11/using-llms-for-code/