{
  "id": "wall-of-diff",
  "title": "The wall of diff",
  "guide": "git/commit-small",
  "prompt": "Pick the agent's next move, then see where it leads:",
  "setup": [
    {
      "role": "user",
      "text": "Good session: the retry logic, the config rename, and the new export flag all work. Commit it."
    },
    {
      "role": "agent",
      "text": "Three hours of work, three unrelated changes, currently one big pile in the working tree."
    }
  ],
  "options": [
    {
      "key": "A",
      "label": "Committing everything now: \"Add retry logic, rename config keys, add export flag\". One commit, all 23 files, session captured.",
      "kind": "baseline",
      "outcome": [
        {
          "role": "user",
          "text": "The retry logic is looping forever in production. Revert it."
        },
        {
          "role": "agent",
          "text": "The revert takes the config rename and the export flag with it: they're welded into the same commit. I'll have to revert all three, then re-apply two of them by hand from the old diff. Twenty minutes of surgery for what should have been one command."
        }
      ],
      "verdict": "One commit, three purposes: revert stops being surgical, bisect stops being useful, and the 23-file diff was never really reviewable in the first place.",
      "cites": []
    },
    {
      "key": "B",
      "label": "Splitting into three single-purpose commits: staging the retry files first (\"Add retry with backoff to the sync client\"), then the rename, then the flag. Showing you each diff stat as I go.",
      "kind": "correct",
      "outcome": [
        {
          "role": "user",
          "text": "The retry logic is looping forever in production. Revert it."
        },
        {
          "role": "agent",
          "text": "git revert a1b2c3d: done, retry gone, rename and flag untouched. And for next time: the redo branch starts from a clean history where the retry change is one readable diff."
        }
      ],
      "verdict": "Three purposes, three commits: the bad one reverts in one command, the good ones stand, and each diff was small enough to actually read at review time.",
      "cites": []
    },
    {
      "key": "C",
      "label": "I'll commit per file for maximum granularity: 23 files, 23 commits, each one atomic.",
      "kind": "plausible",
      "outcome": [
        {
          "role": "agent",
          "text": "Done: 23 commits. Caveat I should flag: the retry change spans 6 of them, so commits 4 through 9 each leave the build broken until the next lands."
        },
        {
          "role": "user",
          "text": "So bisect lands on a broken-by-construction commit, and reverting the retry means finding six needles."
        }
      ],
      "verdict": "Granularity by file, not by purpose: every commit is small and none is coherent. The unit of a commit is the change that stands together: builds green, reverts whole.",
      "cites": []
    }
  ]
}