Users with 'commit.gpgsign = true' in their global git config got a
pinentry popup (or a failed commit) every time the agent took a
background filesystem snapshot — every write_file, patch, or diff
mid-session. With GPG_TTY unset, pinentry-qt/gtk would spawn a GUI
window, constantly interrupting the session.
The shadow repo is internal Hermes infrastructure. It must not
inherit user-level git settings (signing, hooks, aliases, credential
helpers, etc.) under any circumstance.
Fix is layered:
1. _git_env() sets GIT_CONFIG_GLOBAL=os.devnull,
GIT_CONFIG_SYSTEM=os.devnull, and GIT_CONFIG_NOSYSTEM=1. Shadow
git commands no longer see ~/.gitconfig or /etc/gitconfig at all
(uses os.devnull for Windows compat).
2. _init_shadow_repo() explicitly writes commit.gpgsign=false and
tag.gpgSign=false into the shadow's own config, so the repo is
correct even if inspected or run against directly without the
env vars, and for older git versions (<2.32) that predate
GIT_CONFIG_GLOBAL.
3. _take() passes --no-gpg-sign inline on the commit call. This
covers existing shadow repos created before this fix — they will
never re-run _init_shadow_repo (it is gated on HEAD not existing),
so they would miss layer 2. Layer 1 still protects them, but the
inline flag guarantees correctness at the commit call itself.
Existing checkpoints, rollback, list, diff, and restore all continue
to work — history is untouched. Users who had the bug stop getting
pinentry popups; users who didn't see no observable change.
Tests: 5 new regression tests in TestGpgAndGlobalConfigIsolation,
including a full E2E repro with fake HOME, global gpgsign=true, and
a deliberately broken GPG binary — checkpoint succeeds regardless.
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