diff --git a/README.md b/README.md
index f9d578f..2905b74 100644
--- a/README.md
+++ b/README.md
@@ -7,7 +7,7 @@
 
 ## 0) 현재 완성도 빠른 진단
 
-현 시점 기준 기능 완성도(실사용 관점): **약 80%**
+현 시점 기준 기능 완성도(실사용 관점): **약 88%**
 
 - 완료
   - CSV 기초 요약(행/열/결측/숫자 통계)
@@ -16,9 +16,8 @@
   - 브라우저 UI(`bitnet-analyze ui`)
   - **윈도우 데스크톱 UI(`bitnet-analyze desktop`, `BitNet_Desktop_Start.bat`)**
 - 남은 과제
-  - 대용량 CSV(수십~수백 MB) 스트리밍 처리
   - 시각화(차트) 및 리포트 내보내기
-  - 실행 전 환경진단(ollama 설치 여부 자동 점검)
+  - 데이터 전처리 규칙(날짜/카테고리 자동 인식) 고도화
 
 ### 파일 붙여넣기 분석 가능 범위
 
@@ -127,6 +126,8 @@ jupyter lab
 - 패키지 설치(`pip install -e .`)
 - `pythonw`로 GUI 실행(콘솔창 없이)
 
+데스크톱 UI 내 `환경진단` 버튼으로 Ollama 설치/실행/모델 보유 여부를 즉시 확인할 수 있습니다.
+
 ---
 
 ## 4) BitNet 기본 설정값 (안정성 우선)
@@ -206,6 +207,9 @@ bitnet-analyze ui --host 127.0.0.1 --port 8765
 
 # 5) 데스크톱 UI 실행
 bitnet-analyze desktop
+
+# 6) 환경 진단
+bitnet-analyze doctor --model bitnet:latest
 ```
 
 ---
diff --git a/bitnet_tools/analysis.py b/bitnet_tools/analysis.py
index 5a615ab..0474ebe 100644
--- a/bitnet_tools/analysis.py
+++ b/bitnet_tools/analysis.py
@@ -5,7 +5,6 @@
 import io
 import json
 from pathlib import Path
-from statistics import mean
 from typing import Any
 
 
@@ -40,11 +39,20 @@ def _to_float(value: str) -> float | None:
 
 
 def summarize_rows(rows: list[dict[str, str]], columns: list[str]) -> DataSummary:
+    return summarize_reader(rows, columns)
+
+
+def summarize_reader(rows: Any, columns: list[str]) -> DataSummary:
     missing_counts = {col: 0 for col in columns}
-    numeric_values: dict[str, list[float]] = {col: [] for col in columns}
+    numeric_counts: dict[str, int] = {col: 0 for col in columns}
+    numeric_sums: dict[str, float] = {col: 0.0 for col in columns}
+    numeric_mins: dict[str, float] = {}
+    numeric_maxs: dict[str, float] = {}
     text_seen: dict[str, bool] = {col: False for col in columns}
+    row_count = 0
 
     for row in rows:
+        row_count += 1
         for col in columns:
             raw = (row.get(col) or "").strip()
             if raw == "":
@@ -54,25 +62,30 @@ def summarize_rows(rows: list[dict[str, str]], columns: list[str]) -> DataSummar
             if num is None:
                 text_seen[col] = True
             else:
-                numeric_values[col].append(num)
+                numeric_counts[col] += 1
+                numeric_sums[col] += num
+                if col not in numeric_mins or num < numeric_mins[col]:
+                    numeric_mins[col] = num
+                if col not in numeric_maxs or num > numeric_maxs[col]:
+                    numeric_maxs[col] = num
 
     dtypes: dict[str, str] = {}
     numeric_stats: dict[str, dict[str, float]] = {}
     for col in columns:
-        values = numeric_values[col]
-        if values and not text_seen[col]:
+        count = numeric_counts[col]
+        if count > 0 and not text_seen[col]:
             dtypes[col] = "float"
             numeric_stats[col] = {
-                "count": float(len(values)),
-                "mean": float(mean(values)),
-                "min": float(min(values)),
-                "max": float(max(values)),
+                "count": float(count),
+                "mean": float(numeric_sums[col] / count),
+                "min": float(numeric_mins[col]),
+                "max": float(numeric_maxs[col]),
             }
         else:
             dtypes[col] = "string"
 
     return DataSummary(
-        row_count=len(rows),
+        row_count=row_count,
         column_count=len(columns),
         columns=columns,
         dtypes=dtypes,
@@ -101,9 +114,8 @@ def build_analysis_payload(csv_path: str | Path, question: str) -> dict[str, Any
         if reader.fieldnames is None:
             raise ValueError("CSV header not found")
         columns = [str(c) for c in reader.fieldnames]
-        rows = list(reader)
 
-    summary = summarize_rows(rows, columns)
+        summary = summarize_reader(reader, columns)
 
     return {
         "csv_path": str(path),
@@ -119,8 +131,7 @@ def build_analysis_payload_from_csv_text(csv_text: str, question: str) -> dict[s
         raise ValueError("CSV header not found")
 
     columns = [str(c) for c in reader.fieldnames]
-    rows = list(reader)
-    summary = summarize_rows(rows, columns)
+    summary = summarize_reader(reader, columns)
 
     return {
         "csv_path": "<inline_csv>",
diff --git a/bitnet_tools/cli.py b/bitnet_tools/cli.py
index a762c2d..972aa41 100644
--- a/bitnet_tools/cli.py
+++ b/bitnet_tools/cli.py
@@ -7,6 +7,7 @@
 from pathlib import Path
 
 from .analysis import build_analysis_payload
+from .doctor import collect_environment
 from .web import serve
 
 
@@ -49,12 +50,15 @@ def _build_parser() -> argparse.ArgumentParser:
 
     subparsers.add_parser("desktop", help="Run Windows desktop UI")
 
+    doctor_parser = subparsers.add_parser("doctor", help="Run local environment diagnostics")
+    doctor_parser.add_argument("--model", default=None, help="Optional model tag to check availability")
+
     return parser
 
 
 def main(argv: list[str] | None = None) -> int:
     raw_args = list(sys.argv[1:] if argv is None else argv)
-    if raw_args and raw_args[0] not in {"analyze", "ui", "desktop", "-h", "--help"}:
+    if raw_args and raw_args[0] not in {"analyze", "ui", "desktop", "doctor", "-h", "--help"}:
         raw_args.insert(0, "analyze")
 
     parser = _build_parser()
@@ -70,6 +74,11 @@ def main(argv: list[str] | None = None) -> int:
         launch_desktop()
         return 0
 
+    if args.command == "doctor":
+        report = collect_environment(model=args.model)
+        print(json.dumps(report, ensure_ascii=False, indent=2))
+        return 0
+
     if args.command == "analyze":
         payload = build_analysis_payload(args.csv, args.question)
         args.out.write_text(
diff --git a/bitnet_tools/desktop.py b/bitnet_tools/desktop.py
index e0a655e..2cc0e8b 100644
--- a/bitnet_tools/desktop.py
+++ b/bitnet_tools/desktop.py
@@ -8,6 +8,7 @@
 from tkinter import filedialog, messagebox, ttk
 
 from .analysis import build_analysis_payload
+from .doctor import collect_environment
 
 
 def run_ollama(model: str, prompt: str) -> str:
@@ -84,7 +85,8 @@ def _build_ui(self) -> None:
         self.model.insert(0, "bitnet:latest")
         self.model.pack(side="left", fill="x", expand=True, padx=8)
 
-        ttk.Button(model_row, text="1) 분석", command=self._analyze_async).pack(side="left", padx=(8, 4))
+        ttk.Button(model_row, text="환경진단", command=self._doctor_async).pack(side="left", padx=(8, 4))
+        ttk.Button(model_row, text="1) 분석", command=self._analyze_async).pack(side="left", padx=(0, 4))
         ttk.Button(model_row, text="2) BitNet 실행", command=self._run_model_async).pack(side="left")
 
         self.status = ttk.Label(frame, text="대기 중")
@@ -153,6 +155,19 @@ def _analyze(self) -> None:
         except Exception as exc:
             self._on_ui(self._set_status, f"오류: {exc}")
 
+
+    def _doctor_async(self) -> None:
+        threading.Thread(target=self._doctor, daemon=True).start()
+
+    def _doctor(self) -> None:
+        self._on_ui(self._set_status, "환경 진단 중...")
+        report = collect_environment(model=self.model.get().strip() or None)
+        self._on_ui(self._set_text, self.answer, json.dumps(report, ensure_ascii=False, indent=2))
+        if report.get("ollama_installed") and report.get("ollama_running"):
+            self._on_ui(self._set_status, "환경 진단 완료 (정상)")
+        else:
+            self._on_ui(self._set_status, "환경 진단 완료 (확인 필요)")
+
     def _run_model_async(self) -> None:
         threading.Thread(target=self._run_model, daemon=True).start()
 
diff --git a/bitnet_tools/doctor.py b/bitnet_tools/doctor.py
new file mode 100644
index 0000000..2758eea
--- /dev/null
+++ b/bitnet_tools/doctor.py
@@ -0,0 +1,51 @@
+from __future__ import annotations
+
+import platform
+import shutil
+import subprocess
+import sys
+from typing import Any
+
+
+def _run(cmd: list[str]) -> tuple[int, str, str]:
+    proc = subprocess.run(cmd, capture_output=True, text=True, check=False)
+    return proc.returncode, proc.stdout.strip(), proc.stderr.strip()
+
+
+def collect_environment(model: str | None = None) -> dict[str, Any]:
+    info: dict[str, Any] = {
+        "python": sys.version.split()[0],
+        "platform": platform.platform(),
+        "ollama_installed": False,
+        "ollama_running": False,
+    }
+
+    ollama_path = shutil.which("ollama")
+    if not ollama_path:
+        info["diagnosis"] = "ollama not found in PATH"
+        return info
+
+    info["ollama_installed"] = True
+    info["ollama_path"] = ollama_path
+
+    code, out, err = _run(["ollama", "--version"])
+    if code == 0:
+        info["ollama_version"] = out
+    else:
+        info["ollama_version_error"] = err or out or "unknown error"
+
+    code, out, err = _run(["ollama", "list"])
+    if code == 0:
+        info["ollama_running"] = True
+        models = []
+        lines = [line for line in out.splitlines() if line.strip()]
+        for line in lines[1:]:
+            models.append(line.split()[0])
+        info["models"] = models
+        if model:
+            info["model_requested"] = model
+            info["model_available"] = any(m.startswith(model) for m in models)
+    else:
+        info["ollama_list_error"] = err or out or "failed to query ollama"
+
+    return info
diff --git a/tests/test_analysis.py b/tests/test_analysis.py
index d9d6454..e50c735 100644
--- a/tests/test_analysis.py
+++ b/tests/test_analysis.py
@@ -38,3 +38,13 @@ def test_build_analysis_payload_from_csv_text():
 
     assert payload["csv_path"] == "<inline_csv>"
     assert payload["summary"]["row_count"] == 2
+
+
+def test_streaming_summary_keeps_mixed_type_as_string(tmp_path):
+    p = tmp_path / "mixed.csv"
+    p.write_text("a,b\n1,10\n2,hello\n", encoding="utf-8")
+
+    payload = build_analysis_payload(p, "검증")
+
+    assert payload["summary"]["dtypes"]["b"] == "string"
+    assert "b" not in payload["summary"]["numeric_stats"]
diff --git a/tests/test_cli.py b/tests/test_cli.py
index 56d148c..7140864 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -27,3 +27,18 @@ def fake_serve(host: str, port: int):
 
     assert code == 0
     assert called == {"host": "0.0.0.0", "port": 9999}
+
+
+def test_cli_doctor_mode(monkeypatch, capsys):
+    monkeypatch.setattr(
+        cli,
+        "collect_environment",
+        lambda model=None: {"ollama_installed": True, "model_requested": model},
+    )
+
+    code = cli.main(["doctor", "--model", "bitnet:latest"])
+
+    assert code == 0
+    out = capsys.readouterr().out
+    assert '"ollama_installed": true' in out
+    assert '"model_requested": "bitnet:latest"' in out