A version of Justin Hileman's Git Pretty diagram in Mermaid.js syntax, for easy refactoring.

git-pretty.md

graph TD;
    A[So you have a mess on your hands] -->|Yep| B[What sort of mess?]

    B -->|An uncommitted mess| C[Do you care enough about your mess to keep it?]
    C -->|Yes| D[Looks like we caught this just in time]
    D --> E[Split off a logical chunk from your mess, stage it, & commit it with a good message.]
    E -->|Still have a mess?| F[No, we're cool now]
    F --> G[Everything is going to be fine]
    E -->|Yes| H[git reset --hard]
    H --> G

    C -->|No| I[git reset --hard]
    I --> G

    B -->|I accidentally committed something| J[My Git history is ugly]
    
    J -->|Has anyone else seen it?| K[No]
    K -->|Not yet| L[Is it already on GitHub?]

    L -->|No| M[How long ago?]
    M -->|Last commit| N[What would make this better?]
    N -->|I forgot to add a file| O[git add myfile]
    O --> P[git commit --amend]
    P --> G

    N -->|A better message| Q[git commit --amend]
    Q --> G

    N -->|Just throw the last commit away| R[git reset --hard HEAD^]
    R --> G

    M -->|It seems like forever ago| S[Should we remove merge commits?]
    S -->|That would do the trick| T[git rebase origin/branch]
    T --> G

    S -->|No, I need to change history| U[Take a mulligan?]
    U -->|Yes| V[We'll reset and commit from scratch]
    V --> W[git reset COMMITISH]
    W --> G

    U -->|No| X[Is anyone downstream?]
    X -->|Yes| Y[Enough to form a lynch mob?]
    Y -->|Yes| Z[It's safest to let it stay ugly then]
    
    Y -->|No| AA[Do you hate them?]
    AA -->|Yes| Z
    AA -->|No| AB[Send them a note, let 'em know you're changing history.]
    AB --> AC[We're going to do an interactive rebase!]
    AC --> AD[DangerZone™, you should git switch -c temporary-branch just to be safe]
    AD --> AE[git rebase -i COMMITISH]
    AE --> AF[...]
    AF --> AG[git push --force origin branch]
    AG --> G

    X -->|No| AC

    J -->|Yes| AH[git revert COMMITISH]
    AH --> AI[(I do not think it means what you think it means.)]
    AH --> G

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For the record, the git-pretty diagram originally appeared on this (now gone) blog post: https://justinhileman.info/article/changing-history With the Internet Archive's Wayback Machine pretty much under permanent attack, there may be no way to recover the original diagram. I have reached out to Justin Hileman for his permission to create a derivative work. If he agrees, I'll move this gist to a new GitHub repository.