From 37af83aca408effa3bda76d2ef6eb5faadd55aed Mon Sep 17 00:00:00 2001
From: Chris Graf <chris@grafhome.net>
Date: Thu, 2 Jul 2026 07:35:03 -0500
Subject: [PATCH] Block `git push --mirror` in the pre-bash guard
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Summary

Extend the force-push guard to catch `git push --mirror`, which
force-overwrites and prunes every remote ref — remote-destructive even
without `--force`. Follow-up to the `+<refspec>` fix (#38).

- add a dedicated `_GUARD_GIT_PUSH_MIRROR` guard and a `--mirror)` arm in
  the post-`push` argument scan
- give it its own message (the force guard's `--force-with-lease` advice
  does not fit a mirror push): run it manually if a full mirror is truly
  intended
- `--prune`/`--all` are left out of scope; `--mirror` is the clear
  remote-destructive gap

Testing

- new `agent-hook-bash-guards-test` cases: `git push --mirror`,
  `--mirror origin`, and `git -C repo push --mirror` are blocked with the
  mirror-specific message; normal pushes, `+refspec`, `--force-with-lease`,
  and `-u` are unaffected
- verified red-green: removing the `--mirror)` arm lets `--mirror` through
  (exit 0)
- full suite green (`./test/agentguard-test`: all suites 0 failed);
  `checkrun lint` clean
---
 bin/agent-hook-pre-bash                 | 11 +++++++++++
 test/suites/agent-hook-bash-guards-test | 13 +++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/bin/agent-hook-pre-bash b/bin/agent-hook-pre-bash
index 451d919..1a2fd5c 100755
--- a/bin/agent-hook-pre-bash
+++ b/bin/agent-hook-pre-bash
@@ -376,6 +376,7 @@ _hook_run_guards() {
   _GUARD_GIT_RESET_HARD=0
   _GUARD_GIT_CLEAN_FORCE=0
   _GUARD_GIT_PUSH_FORCE=0
+  _GUARD_GIT_PUSH_MIRROR=0
   _GUARD_TTY_REQUIRED=0
   _GUARD_GIT_COMMIT=0
   _GUARD_SL_COMMIT=0
@@ -508,6 +509,12 @@ _hook_run_guards() {
                 _GUARD_GIT_PUSH_FORCE=1
                 break
                 ;;
+              --mirror)
+                # --mirror force-overwrites AND prunes every remote ref, so it is
+                # remote-destructive even without --force.
+                _GUARD_GIT_PUSH_MIRROR=1
+                break
+                ;;
               --*) ;;
               -?*) [[ "${word#-}" == *f* ]] && {
                 _GUARD_GIT_PUSH_FORCE=1
@@ -746,6 +753,10 @@ fi
 [ "$_GUARD_GIT_PUSH_FORCE" -eq 1 ] &&
   _hook_block 'git push --force rewrites remote history without a lease. Use --force-with-lease for reviewed restacks.'
 
+# Block git push --mirror — force-overwrites and prunes every remote ref.
+[ "$_GUARD_GIT_PUSH_MIRROR" -eq 1 ] &&
+  _hook_block 'git push --mirror force-overwrites and prunes every remote ref. Run it manually if a full mirror is truly intended.'
+
 # Block interactive TTY commands — they will silently hang the agent turn.
 [ "$_GUARD_TTY_REQUIRED" -eq 1 ] &&
   _hook_block 'This command requires an interactive TTY and will hang. Use a non-interactive alternative (e.g. PAGER=cat, --no-pager, -batch).'
diff --git a/test/suites/agent-hook-bash-guards-test b/test/suites/agent-hook-bash-guards-test
index 2ab6a04..3f49950 100755
--- a/test/suites/agent-hook-bash-guards-test
+++ b/test/suites/agent-hook-bash-guards-test
@@ -174,6 +174,19 @@ _assert_not_contains "git push src:dst: no BLOCKED" "BLOCKED" "$HOOK_STDERR"
 _run_hook "$PRE_BASH" '{"tool_input":{"command":"git push -u origin feat/foo"}}'
 _assert_eq "git push -u: allowed" "0" "$HOOK_EXIT"
 
+# --mirror force-overwrites and prunes every remote ref — blocked, with its own
+# (non-force) message so the advice fits.
+_run_hook "$PRE_BASH" '{"tool_input":{"command":"git push --mirror"}}'
+_assert_eq "git push --mirror: blocked" "2" "$HOOK_EXIT"
+_assert_contains "git push --mirror: BLOCKED msg" "BLOCKED" "$HOOK_STDERR"
+_assert_contains "git push --mirror: mirror-specific message" "--mirror force-overwrites" "$HOOK_STDERR"
+
+_run_hook "$PRE_BASH" '{"tool_input":{"command":"git push --mirror origin"}}'
+_assert_eq "git push --mirror origin: blocked" "2" "$HOOK_EXIT"
+
+_run_hook "$PRE_BASH" '{"tool_input":{"command":"git -C /tmp/repo push --mirror"}}'
+_assert_eq "git -C push --mirror: blocked" "2" "$HOOK_EXIT"
+
 # echo of git push --force is prose
 _run_hook "$PRE_BASH" '{"tool_input":{"command":"echo git push --force"}}'
 _assert_eq "echo git push --force: allowed" "0" "$HOOK_EXIT"