Tech Cafe - Git

Git Archaeologist

2026-08-26T00:00:00+00:00

Git’s forensic tools are surgical. git log -S</code>, git blame</code> and git bisect</code> each answer a precise question you already know how to ask. I wanted to know whether a model that can hold an entire repository history in context answers a different kind of question, the diffuse kind where the answer lives across many commits at once.

So I built a harness: ten questions against one real repository, with ground truth verified by running git</code> rather than by trusting my memory. Three of the ten were negative controls, asking about things that never happened, because a model that agrees with every premise you hand it is not doing archaeology.

The model answered 10/10 correctly, including all three controls, and cited 103 commit SHAs of which 102 resolve to real commits. It fabricated nothing. It was also between 150 and 4,000 times slower than Git on the questions Git can answer.

The result I did not expect was a ceiling. Datasette is a mid-sized project, nine years and 3,406 commits, and its full history is roughly four million tokens, about four times the window. I stripped docs, lockfiles, images and vendored assets, then capped diff sizes, and never got within twice the budget. The bulk is not a few large blobs, it is 2,663 commits of real source diff. The run used the largest chronological prefix that fit, which was the first 31%.

So “put the whole history in context” has a size limit that nobody advertises, and for any project with real history you are already past it. Worth measuring before you design around it.

Built with: Python, Git, OpenRouter

Repo is private for now.



Managing Multiple Git Identities on One Machine
2026-02-05T00:00:00+00:00
TL;DR: Want separate Git emails per project? Just don’t use --global</code>.</strong></p>
The Problem:</strong> So I ran into this situation where I needed one project folder to use my university credentials while keeping my personal Gmail for literally everything else in VS Code. Classic identity crisis, but make it Git.</p>
Honestly thought this would be a nightmare to set up, but Git actually makes it pretty straightforward once you know the trick.</p>
Solution: Local vs Global Git Config</h3>
Here is the thing I wish someone had told me earlier: stop using --global</code> for everything.</strong> I know it is tempting (one command and you are done!), but global configs apply to every single repository on your machine. Not ideal when you are trying to keep things separate.</p>
For personal identity  (global):</strong></p>
git</span> config</span> -</span>-global</span> user.name</span> "</span>personal username</span>"</span></span>
git</span> config</span> -</span>-global</span> user.email</span> "</span>personal email</span>"</span></span></code></pre>
For uni project (local: run this inside that specific folder):</strong></p>
git</span> config</span> user.name</span> "</span>uni username</span>"</span></span>
git</span> config</span> user.email</span> "</span>uni email</span>"</span></span></code></pre>
See the difference? No --global</code> flag means the config only applies to that one repository. Problem  solved.</p>
Paranoid and want to verify?</strong> I found this super helpful command to check which email was actually used for your last commit:</p>
git</span> show</span> -</span>s</span> -</span>-format=</span>'</span>Author: %ae%nCommitter: %ce</span>'</span> HEAD</span></span></code></pre>
This shows you both the author and committer email from your most recent commit. Saved me from some potential embarrassment when I wasn’t sure if I had configured things correctly!</p>
Bonus Learning: Git Reset Flags (Proceed with Caution)</h3>
I also learned about git reset</code> and honestly it is Kind of terrifying.</p>


git reset --soft HEAD~1</code></strong>: Removes your last commit but keeps all your changes staged. Perfect for those “oops, typo in the commit message” moments. Very forgiving, 10/10 would use again.</p>
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git reset --hard HEAD~1</code></strong>: Deletes the last commit AND all your changes. Like completely GONE. Forever. No take-backs. (Yeah… never gonna try using --hard</code> unless I am absolutely certain and have sacrificed the appropriate offerings to the Git gods.)</p>
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Real talk:</strong> Always double-check before using --hard</code>. Your past self worked hard on that code, and your future self will definitely not appreciate having to rewrite everything at midnight.</p>