Git metadata dropped in a git worktree (.git file with gitdir: pointer not followed) #331

Summary

Recording inside a git worktree makes the agent drop all git metadata, with a warning on every recording. Worktrees are the natural way to hold BASE and HEAD for a two-revision comparison (the appmap-review / gold-traces workflow), so this is the flagship workflow losing commit metadata.

Agent 1.30.1, Ubuntu, Java 17, spring-petclinic @ b26f235, Maven Surefire.

Repro

git clone https://github.com/spring-projects/spring-petclinic && cd spring-petclinic
git worktree add ../petclinic-base b26f235
cd ../petclinic-base
mvn -Dtest=PetClinicIntegrationTests#testOwnerDetails test   # agent attached via -javaagent

Observed

Twice per test run:

AppMap WARN: Current git repository is an unsupported configuration.
No git metadata will be collected, and source paths may be incorrect.

The recordings have no metadata.git. The same test in the main checkout records git.commit, git.branch, etc.

Cause

In a worktree .git is a file containing gitdir: /path/to/repo/.git/worktrees/<name>, not a directory. The agent's repository detection expects a directory and does not follow the pointer.

Expected

Follow the gitdir: pointer (and its commondir) and collect metadata as in a normal checkout. If worktrees will not be supported, the docs/skills should say to use two full clones.

Written by Devin