diff --git a/bin/ingo b/bin/ingo
index 3e7512b..ad943ba 100755
--- a/bin/ingo
+++ b/bin/ingo
@@ -48,6 +48,7 @@ doctor() {
     ingo_require_bin grep
     ingo_require_bin pdftotext
     ingo_require_bin pdftoppm
+    ingo_require_tesseract_lang "$INGO_LANG"
   fi
   echo "ok"
 }
diff --git a/lib/env.sh b/lib/env.sh
index 80e4ee0..3a2b78a 100755
--- a/lib/env.sh
+++ b/lib/env.sh
@@ -58,6 +58,24 @@ ingo_require_bin() {
   fi
 }
 
+ingo_require_tesseract_lang() {
+  local lang="$1"
+  local list line
+  if ! list="$(tesseract --list-langs 2>/dev/null)"; then
+    echo "failed to list tesseract languages via 'tesseract --list-langs'" >&2
+    return 5
+  fi
+
+  while IFS= read -r line; do
+    if [ "$line" = "$lang" ]; then
+      return 0
+    fi
+  done <<< "$list"
+
+  echo "missing OCR language data for INGO_LANG=$lang (not found in 'tesseract --list-langs')" >&2
+  return 5
+}
+
 ingo_require_env() {
   local missing=0
   for key in UPSTASH_VECTOR_REST_URL UPSTASH_VECTOR_REST_TOKEN; do
diff --git a/tests/doctor_lang_check_test.sh b/tests/doctor_lang_check_test.sh
new file mode 100755
index 0000000..ac2c702
--- /dev/null
+++ b/tests/doctor_lang_check_test.sh
@@ -0,0 +1,133 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+
+fail() {
+  echo "FAIL: $*" >&2
+  exit 1
+}
+
+assert_eq() {
+  local got="$1"
+  local want="$2"
+  local msg="$3"
+  if [ "$got" != "$want" ]; then
+    fail "$msg (got='$got' want='$want')"
+  fi
+}
+
+assert_contains() {
+  local haystack="$1"
+  local needle="$2"
+  local msg="$3"
+  if ! printf "%s" "$haystack" | grep -F -- "$needle" >/dev/null; then
+    fail "$msg (missing '$needle')"
+  fi
+}
+
+make_mock_bin() {
+  local dir="$1"
+
+  cat > "$dir/curl" <<'EOF'
+#!/usr/bin/env bash
+exit 0
+EOF
+  cat > "$dir/jq" <<'EOF'
+#!/usr/bin/env bash
+exit 0
+EOF
+  cat > "$dir/awk" <<'EOF'
+#!/usr/bin/env bash
+exit 0
+EOF
+  cat > "$dir/grep" <<'EOF'
+#!/usr/bin/env bash
+exit 0
+EOF
+  cat > "$dir/pdftotext" <<'EOF'
+#!/usr/bin/env bash
+exit 0
+EOF
+  cat > "$dir/pdftoppm" <<'EOF'
+#!/usr/bin/env bash
+exit 0
+EOF
+
+  chmod +x "$dir/curl" "$dir/jq" "$dir/awk" "$dir/grep" "$dir/pdftotext" "$dir/pdftoppm"
+}
+
+test_doctor_fails_when_lang_missing() {
+  local mock_bin out status
+  mock_bin="$(mktemp -d)"
+  make_mock_bin "$mock_bin"
+
+  cat > "$mock_bin/tesseract" <<'EOF'
+#!/usr/bin/env bash
+if [ "${1:-}" = "--list-langs" ]; then
+  cat <<'OUT'
+List of available languages in "/tmp/tessdata/" (2):
+eng
+spa_old
+OUT
+  exit 0
+fi
+exit 0
+EOF
+  chmod +x "$mock_bin/tesseract"
+
+  set +e
+  out="$(
+    PATH="$mock_bin:$PATH" \
+    UPSTASH_VECTOR_REST_URL="https://example.test" \
+    UPSTASH_VECTOR_REST_TOKEN="token" \
+    INGO_ROLE="all" \
+    INGO_LANG="spa" \
+    "$ROOT_DIR/bin/ingo" doctor 2>&1
+  )"
+  status=$?
+  set -e
+
+  assert_eq "$status" "5" "doctor exits non-zero when OCR language is missing"
+  assert_contains "$out" "missing OCR language data for INGO_LANG=spa" "doctor error mentions missing INGO_LANG"
+}
+
+test_doctor_passes_when_lang_present_exact_match() {
+  local mock_bin out
+  mock_bin="$(mktemp -d)"
+  make_mock_bin "$mock_bin"
+
+  cat > "$mock_bin/tesseract" <<'EOF'
+#!/usr/bin/env bash
+if [ "${1:-}" = "--list-langs" ]; then
+  cat <<'OUT'
+List of available languages in "/tmp/tessdata/" (3):
+eng
+spa
+spa_old
+OUT
+  exit 0
+fi
+exit 0
+EOF
+  chmod +x "$mock_bin/tesseract"
+
+  out="$(
+    PATH="$mock_bin:$PATH" \
+    UPSTASH_VECTOR_REST_URL="https://example.test" \
+    UPSTASH_VECTOR_REST_TOKEN="token" \
+    INGO_ROLE="all" \
+    INGO_LANG="spa" \
+    "$ROOT_DIR/bin/ingo" doctor 2>&1
+  )"
+  assert_eq "$out" "ok" "doctor prints ok when OCR language is installed"
+}
+
+main() {
+  test_doctor_fails_when_lang_missing
+  test_doctor_passes_when_lang_present_exact_match
+  echo "ok"
+}
+
+main "$@"