fix(gh-cli): fall back to well-known install paths for shim PATH walk (closes #145)

.claude-plugin/marketplace.json

@@ -115,7 +115,7 @@
     },
     {
       "name": "gh-cli",
-      "version": "1.4.1",
+      "version": "1.4.2",
       "description": "Intercepts GitHub URL fetches and curl/wget commands, redirecting to the authenticated gh CLI.",
       "author": {
         "name": "William Tan",

plugins/gh-cli/.claude-plugin/plugin.json

@@ -1,6 +1,6 @@
 {
   "name": "gh-cli",
-  "version": "1.4.1",
+  "version": "1.4.2",
   "description": "Intercepts GitHub URL fetches and curl/wget commands, redirecting to the authenticated gh CLI.",
   "author": {
     "name": "William Tan",

plugins/gh-cli/hooks/shims/gh

@@ -65,5 +65,38 @@ for dir in "${path_entries[@]}"; do
   fi
 done
 
+# Fallback for PATH-stripping environments. Some parents fork with PATH
+# stripped to internal/system dirs only — most notably Homebrew's superenv
+# during `brew install` with HOMEBREW_VERIFY_ATTESTATIONS=true (issue #145):
+# the shim wins ensure_executable!'s ORIGINAL_PATHS resolution, then runs
+# under a stripped child PATH that no longer contains the Homebrew prefix,
+# so the PATH walk above can't find the real gh.
+#
+# Check well-known install paths directly. The Cellar opt symlinks
+# (.../opt/gh/bin/gh) are stable across upgrades; the prefix bin entries
+# cover manual installs and non-Homebrew system packages. Tests can
+# override the list via GH_SHIM_FALLBACKS (colon-separated absolute paths).
+if [[ -n "${GH_SHIM_FALLBACKS:-}" ]]; then
+  IFS=: read -ra fallbacks <<<"$GH_SHIM_FALLBACKS"
+else
+  fallbacks=(
+    /opt/homebrew/opt/gh/bin/gh
+    /opt/homebrew/bin/gh
+    /usr/local/opt/gh/bin/gh
+    /usr/local/bin/gh
+    /home/linuxbrew/.linuxbrew/opt/gh/bin/gh
+    /home/linuxbrew/.linuxbrew/bin/gh
+    /usr/bin/gh
+  )
+fi
+for fallback in "${fallbacks[@]}"; do
+  if [[ -x "$fallback" ]]; then
+    set +e
+    exec "$fallback" "$@"
+    echo "ERROR: gh-cli shim: failed to exec $fallback (exit $?)" >&2
+    exit 126
+  fi
+done
+
 echo "ERROR: real gh binary not found on PATH" >&2
 exit 127

plugins/gh-cli/hooks/shims/gh-shim.bats

@@ -23,6 +23,7 @@ setup() {
 
 teardown() {
   rm -rf "$FAKE_GH_DIR"
+  [[ -n "${STRIP_PATH_ESSENTIALS_DIR:-}" ]] && rm -rf "$STRIP_PATH_ESSENTIALS_DIR"
   export PATH="$ORIG_PATH"
 }
 
@@ -342,5 +343,103 @@ assert_blocked() {
     path_without_gh="${path_without_gh:+${path_without_gh}:}$dir"
   done
   export PATH="${SHIM_DIR}:${path_without_gh}"
+  # Neutralize the Homebrew-superenv fallback list so this test exercises the
+  # PATH-walk branch in isolation (CI runners often have /usr/bin/gh installed,
+  # which the default fallback list would pick up).
+  export GH_SHIM_FALLBACKS="/__gh_shim_test_no_fallback__/gh"
   run -127 bash -c '"$0" "$@" 2>&1' "$SHIM" pr list
 }
+
+# =============================================================================
+# Homebrew superenv fallback (issue #145)
+# =============================================================================
+#
+# The shim wins ensure_executable!'s ORIGINAL_PATHS resolution inside
+# Homebrew, then forks under a stripped PATH that no longer contains the
+# Homebrew prefix. Without a fallback the PATH walk fails and `brew install`
+# breaks under HOMEBREW_VERIFY_ATTESTATIONS=true. These tests pin that the
+# fallback fires only when the PATH walk finds nothing.
+
+# Helper: rebuild PATH with the shim dir and only directories that don't
+# contain a gh binary, so the PATH walk is forced into the fallback path.
+# On CI runners gh is apt-installed into /usr/bin alongside bash/rm/mktemp,
+# so naively skipping every dir that contains gh strips core utilities. We
+# symlink the essentials we need (run_shim invokes `bash`, teardown uses
+# `rm`, several tests call `mktemp`) into a clean dir and keep that on PATH.
+strip_path_of_gh() {
+  local path_without_gh=""
+  local IFS=:
+  for dir in $ORIG_PATH; do
+    [[ "$dir" == "$FAKE_GH_DIR" ]] && continue
+    [[ -x "$dir/gh" ]] && continue
+    path_without_gh="${path_without_gh:+${path_without_gh}:}$dir"
+  done
+  STRIP_PATH_ESSENTIALS_DIR="$(mktemp -d)"
+  local cmd cmd_path
+  for cmd in bash sh rm mktemp printf chmod cat env; do
+    if cmd_path="$(command -v "$cmd" 2>/dev/null)"; then
+      ln -sf "$cmd_path" "${STRIP_PATH_ESSENTIALS_DIR}/${cmd}"
+    fi
+  done
+  export PATH="${SHIM_DIR}:${STRIP_PATH_ESSENTIALS_DIR}${path_without_gh:+:${path_without_gh}}"
+}
+
+@test "shim: falls back to GH_SHIM_FALLBACKS when PATH walk finds nothing" {
+  strip_path_of_gh
+  export GH_SHIM_FALLBACKS="$FAKE_GH_DIR/gh"
+  run_shim pr list
+  assert_passthrough
+}
+
+@test "shim: prefers PATH-found gh over fallback" {
+  # FAKE_GH_DIR is on PATH (setup) and emits REAL_GH_CALLED. If the shim
+  # incorrectly preferred the fallback, output would carry MARKER_FALLBACK
+  # instead.
+  local marker_dir
+  marker_dir="$(mktemp -d)"
+  printf '#!/usr/bin/env bash\necho "MARKER_FALLBACK"\n' >"$marker_dir/gh"
+  chmod +x "$marker_dir/gh"
+  export GH_SHIM_FALLBACKS="$marker_dir/gh"
+  run_shim pr list
+  assert_passthrough
+  if [[ "$output" == *"MARKER_FALLBACK"* ]]; then
+    echo "Unexpected fallback invocation:"
+    echo "$output"
+    return 1
+  fi
+  rm -rf "$marker_dir"
+}
+
+@test "shim: tries fallbacks in order, skipping non-executable entries" {
+  strip_path_of_gh
+  local nonexec_dir
+  nonexec_dir="$(mktemp -d)"
+  : >"$nonexec_dir/gh" # exists but not executable
+  export GH_SHIM_FALLBACKS="$nonexec_dir/gh:$FAKE_GH_DIR/gh"
+  run_shim issue view 1
+  assert_passthrough
+  rm -rf "$nonexec_dir"
+}
+
+@test "shim: exits 127 when neither PATH nor fallback have gh" {
+  strip_path_of_gh
+  export GH_SHIM_FALLBACKS="/__gh_shim_test_no_fallback__/gh"
+  run -127 bash -c '"$0" "$@" 2>&1' "$SHIM" pr list
+}
+
+@test "shim: anti-pattern checks fire before fallback (api contents)" {
+  # Even when gh is reachable only via fallback, the deny rules run first,
+  # exit 1, and never invoke the fallback binary.
+  strip_path_of_gh
+  export GH_SHIM_FALLBACKS="$FAKE_GH_DIR/gh"
+  run_shim api repos/owner/repo/contents/file.txt
+  assert_blocked
+}
+
+@test "shim: anti-pattern checks fire before fallback (clone temp path)" {
+  strip_path_of_gh
+  export GH_SHIM_FALLBACKS="$FAKE_GH_DIR/gh"
+  unset CLAUDE_SESSION_ID 2>/dev/null || true
+  run_shim repo clone owner/repo /tmp/repos/repo
+  assert_blocked
+}