# Trace how code evolved through its history

Have Claude Code read the commit history of a file and explain how it reached its current shape and why, with commits cited as evidence.

Paste into: **Claude Code**, started in your project folder

## Prompt template

How the builder on the page fills in this template, so you can do the same:

- `{{key}}` becomes the text entered for that field, exactly as typed. Empty text, or text that is only whitespace (spaces, tabs or line breaks), counts as empty: a required field then becomes `[fill in: <label>]` with its label, and an optional field becomes nothing.
- For a choice field, `{{key}}` becomes the text of the chosen option, or of the default when none is chosen.
- Text between `{{#key}}` and `{{/key}}` stays only when that field is not empty; a choice field always counts as filled. The markers themselves are removed, and a marker that stands alone on its line takes its line break with it.
- Each value is inserted once, as it is: `{{…}}` inside a value stays as typed.

```text
Look through the commit history of {{path}} and summarize how it evolved and why.
{{#question}}

What I want to understand:
{{question}}
{{/question}}
{{#range}}

Limit the history to: {{range}}
{{/range}}

Use the version control history: the log, blame for the current lines, and the diffs of the commits that matter. Read commit messages and any linked issues or pull requests you can reach. Only read. Do not check out other branches, change history, or edit files.

Report:
1. A short timeline of the significant changes: commit, date, what changed, and the stated reason. Skip formatting and trivial commits.
2. How the current design came about, in a few sentences.
3. Decisions that still constrain the code today, such as workarounds, compatibility rules or removed features that left traces.
4. Where the history does not explain why. Say so rather than inventing a reason, and mark any reason you inferred from the diff.

Keep it short enough to read in a few minutes.
```

## Fields

- `{{path}}` (required): File, folder or function.
- `{{question}}`: What you want to understand. Optional. A specific decision or oddity you want the history to explain.
- `{{range}}`: Time range or starting point. Optional. Leave empty to cover the whole history.

This site doesn't run Claude or show model output. Results depend on your input and the model you use.

## When to use this template

- The question is why the code looks the way it does, not what it does, and the people who wrote it are not around to ask.
- You are about to remove something that looks unnecessary and want to know whether it was added on purpose, for example as a workaround.
- A file has been rewritten several times and you want the story of those changes before you change it again.

## When not to use it

- The project has little history, or most commits have messages like "wip". Claude can read the diffs, but the reasons behind them may simply not be recorded.
- You want release notes for users. The release notes template groups changes by what readers need to know rather than by how one file evolved.
- You only need to know what the code does today. Use the explanation template; the history adds reading time without adding much.

## Why this structure

- The prompt points Claude at the commit history as the source, because the history records reasons that the current code cannot show.
- The optional question focuses the search on one decision. Without it, Claude summarizes every change equally, including the ones you do not care about.
- The range field keeps a long-lived file manageable, so the summary covers the period that matters to you.
- The read-only line rules out checking out branches or rewriting history, so the investigation leaves your repository exactly as it was.
- Point 4 asks where the history is silent and requires inferred reasons to be marked. Commit history often records what changed without why, and a confident made-up reason is worse than an honest gap.

## Example input (fictional)

File, folder or function:

```
internal/auth/session.go
```

What you want to understand:

```
Why are sessions stored both in the database and in a signed cookie?
```

Time range or starting point:

```
the last 18 months
```

## Follow-ups to send Claude

- Which of the constraints you found are still needed today? Show me the code or tests that depend on each one.
- Add a short comment above the oddest part of the file explaining why it exists, citing the commit that introduced it.
- Find the pull request or issue that introduced the second session store and summarize the discussion, if you can reach it.

## Common mistakes

- Asking about a very large folder over its whole history. Pick one file or function, or set a range, so the summary stays readable.
- Treating an inferred reason as a recorded one. Check which reasons Claude marked as inferred before you rely on them in a design discussion.
- Stopping at the commit messages. When a message is vague, the diff and any linked discussion usually say more, so ask Claude to read them.

## Related templates

- [Explain unfamiliar code and its data flow](https://awesomeclaudeprompts.com/prompts/explain-unfamiliar-code/): Ask Claude Code to explain what one file or module does and how data moves through it, written up in the format you learn from best.
- [Draft release notes from git history](https://awesomeclaudeprompts.com/prompts/release-notes-from-git/): Have Claude Code compare two git tags or branches and draft release notes grouped into breaking changes, features and improvements for your readers.
- [Get oriented in a new codebase](https://awesomeclaudeprompts.com/prompts/codebase-overview/): Ask Claude Code to map an unfamiliar repository: its architecture, key directories, how the parts connect, and where to start for your task.

## Sources

- [Claude Code docs: Prompt library](https://code.claude.com/docs/en/prompt-library) (Anthropic documentation)
- [Claude Code best practices: Provide specific context in your prompts](https://code.claude.com/docs/en/best-practices#provide-specific-context-in-your-prompts) (Anthropic documentation)

---

Awesome Claude Prompts is an independent project. It is not affiliated with, endorsed by, or sponsored by Anthropic. Claude is a trademark of Anthropic, PBC.