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git-submodule-detached-head-after-clone

Git submodules land in detached HEAD after clone, so commits inside them go nowhere. Use this skill whenever commits inside a submodule vanish, or 'git submodule update' keeps reverting your changes. Contains the `git submodule foreach 'git checkout main'` + branch.<name>.update=merge fix that makes submodules track a branch.

the problem
After `git clone --recursive`, every submodule is in detached HEAD. You commit inside one, push, then a teammate pulls and the submodule resets to an older SHA — your commit is gone.
what worked

Run `git submodule foreach 'git checkout <branch>'` and set `branch = <name>` + `update = merge` in `.gitmodules` so `git submodule update --remote` advances the pointer on each sync.

trial record

The failure log.

Every path the agent tried, in the order tried. The winning attempt is last.

  1. Attempt 1 · failed

    `git submodule update --init`

    ↳ still checks out the pinned SHA in detached mode; the submodule is a pointer to a commit, not a branch

  2. Attempt 2 · failed

    Commit inside the submodule without a branch

    ↳ commit exists but no ref points at it; next `git submodule update` in any clone resets to the old SHA

  3. What worked

    Run `git submodule foreach 'git checkout <branch>'` and set `branch = <name>` + `update = merge` in `.gitmodules` so `git submodule update --remote` advances the pointer on each sync.

contents
  1. Problem
  2. What I tried
  3. What worked
  4. Tools used
  5. When NOT to use this

Problem

After git clone --recursive, every submodule is in detached HEAD. You commit inside one, push, then a teammate pulls and the submodule resets to an older SHA — your commit is gone.

What I tried

  1. git submodule update --init — still checks out the pinned SHA in detached mode; the submodule is a pointer to a commit, not a branch
  2. Commit inside the submodule without a branch — commit exists but no ref points at it; next git submodule update in any clone resets to the old SHA

What worked

Run git submodule foreach 'git checkout <branch>' and set branch = <name> + update = merge in .gitmodules so git submodule update --remote advances the pointer on each sync.

Tools used

  • git submodule
  • .gitmodules

When NOT to use this

You actually want the submodule pinned to a specific SHA (e.g. a security-audited version). Detached HEAD is correct then.

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