refactor(#28): IMP-28 L4 _parse_json dedup (4 modules -> src/json_utils)

Consolidate duplicate _parse_json helpers from content_editor.py /
design_director.py / kei_client.py (fuller form) and pipeline.py (simple form)
into shared src/json_utils.parse_json (strict superset). All 18 call-sites
preserved via `parse_json as _parse_json` alias import; no behavior change.

- src/json_utils.py (new): shared helper, fenced/plain-fence/bare-brace patterns
  + list-prefix cleanup fallback.
- tests/test_json_utils.py (new): 9 unit tests pinning parser semantics.
- src/content_editor.py / design_director.py: remove local helper +
  unused `import json` / `import re`.
- src/kei_client.py / pipeline.py: remove local helper; `json` / `re` retained
  (used elsewhere).

Targeted tests 9 passed; full pytest 374 passed (3 pre-existing scripts/
collection errors reproduce on baseline 909bf75, IMP-28 unrelated).

src/content_editor.py

@@ -8,9 +8,7 @@ Kei API 필수. fallback 없음. 성공할 때까지 무한 재시도.
 """
 from __future__ import annotations
 
-import json
 import logging
-import re
 from typing import Any
 
 import anthropic
@@ -18,6 +16,7 @@ import httpx
 
 from src.config import settings
 from src.design_director import BLOCK_SLOTS
+from src.json_utils import parse_json as _parse_json
 from src.sse_utils import stream_sse_tokens
 
 logger = logging.getLogger(__name__)
@@ -441,38 +440,3 @@ async def fill_candidates(
         logger.warning(f"[Phase P] 꼭지 {tid}: 텍스트 편집 파싱 실패")
 
     return candidates
-
-
-def _parse_json(text: str) -> dict[str, Any] | None:
-    """텍스트에서 JSON을 추출한다.
-
-    Kei API가 마크다운 리스트 접두사(- )를 붙여 응답하는 경우에도 처리.
-    """
-    # 전처리: 각 줄 앞의 마크다운 리스트 접두사(- ) 제거
-    lines = text.split("\n")
-    cleaned_lines = []
-    for line in lines:
-        stripped = line.lstrip()
-        if stripped.startswith("- "):
-            cleaned_lines.append(stripped[2:])
-        elif stripped.startswith("* "):
-            cleaned_lines.append(stripped[2:])
-        else:
-            cleaned_lines.append(stripped)
-    cleaned = "\n".join(cleaned_lines)
-
-    # 원본 먼저 시도 → 클린 버전 시도
-    for target in [text, cleaned]:
-        patterns = [
-            r"```json\s*(.*?)```",
-            r"```\s*(.*?)```",
-            r"(\{.*\})",
-        ]
-        for pattern in patterns:
-            match = re.search(pattern, target, re.DOTALL)
-            if match:
-                try:
-                    return json.loads(match.group(1).strip())
-                except json.JSONDecodeError:
-                    continue
-    return None

src/design_director.py

@@ -5,9 +5,7 @@ Step B: 프리셋 안에서 블록 매핑 + 글자 수 가이드 (Sonnet)
 """
 from __future__ import annotations
 
-import json
 import logging
-import re
 from pathlib import Path
 from typing import Any
 
@@ -15,6 +13,7 @@ import httpx
 import yaml
 
 from src.config import settings
+from src.json_utils import parse_json as _parse_json
 from src.sse_utils import stream_sse_tokens
 
 logger = logging.getLogger(__name__)
@@ -1066,38 +1065,3 @@ def _validate_height_budget(blocks: list[dict], preset: dict) -> list[dict]:
         })
 
     return overflows
-
-
-def _parse_json(text: str) -> dict[str, Any] | None:
-    """텍스트에서 JSON을 추출한다.
-
-    Kei API가 마크다운 리스트 접두사(- )를 붙여 응답하는 경우에도 처리.
-    """
-    # 전처리: 각 줄 앞의 마크다운 리스트 접두사(- ) 제거
-    lines = text.split("\n")
-    cleaned_lines = []
-    for line in lines:
-        stripped = line.lstrip()
-        if stripped.startswith("- "):
-            cleaned_lines.append(stripped[2:])
-        elif stripped.startswith("* "):
-            cleaned_lines.append(stripped[2:])
-        else:
-            cleaned_lines.append(stripped)
-    cleaned = "\n".join(cleaned_lines)
-
-    # 원본 먼저 시도 → 클린 버전 시도
-    for target in [text, cleaned]:
-        patterns = [
-            r"```json\s*(.*?)```",
-            r"```\s*(.*?)```",
-            r"(\{.*\})",
-        ]
-        for pattern in patterns:
-            match = re.search(pattern, target, re.DOTALL)
-            if match:
-                try:
-                    return json.loads(match.group(1).strip())
-                except json.JSONDecodeError:
-                    continue
-    return None

src/json_utils.py

@@ -0,0 +1,46 @@
+"""JSON 추출 공용 유틸리티.
+
+Kei / Claude API 응답 텍스트에서 JSON 객체를 추출한다.
+content_editor, design_director, kei_client, pipeline 공통 헬퍼.
+
+응답이 마크다운 리스트 접두사("- " / "* ")로 감싸진 경우에도 처리.
+"""
+from __future__ import annotations
+
+import json
+import re
+from typing import Any
+
+_JSON_PATTERNS: tuple[str, ...] = (
+    r"```json\s*(.*?)```",
+    r"```\s*(.*?)```",
+    r"(\{.*\})",
+)
+
+
+def parse_json(text: str) -> dict[str, Any] | None:
+    """텍스트에서 JSON을 추출한다.
+
+    Kei API가 마크다운 리스트 접두사(- )를 붙여 응답하는 경우에도 처리.
+    원본 → 리스트 접두사 제거 버전 순서로 fenced JSON / plain fenced / 베어 brace 패턴을
+    차례로 시도한다. 모두 실패하면 None.
+    """
+    lines = text.split("\n")
+    cleaned_lines: list[str] = []
+    for line in lines:
+        stripped = line.lstrip()
+        if stripped.startswith("- ") or stripped.startswith("* "):
+            cleaned_lines.append(stripped[2:])
+        else:
+            cleaned_lines.append(stripped)
+    cleaned = "\n".join(cleaned_lines)
+
+    for target in (text, cleaned):
+        for pattern in _JSON_PATTERNS:
+            match = re.search(pattern, target, re.DOTALL)
+            if match:
+                try:
+                    return json.loads(match.group(1).strip())
+                except json.JSONDecodeError:
+                    continue
+    return None

src/kei_client.py

@@ -13,6 +13,7 @@ from typing import Any
 import httpx
 
 from src.config import settings
+from src.json_utils import parse_json as _parse_json
 from src.sse_utils import stream_sse_tokens
 
 logger = logging.getLogger(__name__)
@@ -889,42 +890,6 @@ async def call_kei_overflow_judgment(
         return None
 
 
-def _parse_json(text: str) -> dict[str, Any] | None:
-    """텍스트에서 JSON을 추출한다.
-
-    Kei API가 마크다운 리스트 접두사(- )를 붙여 응답하는 경우에도 처리.
-    """
-    # 전처리: 각 줄 앞의 마크다운 리스트 접두사(- ) 제거
-    # Kei API가 JSON을 마크다운 리스트로 감싸서 응답하는 경우 대응
-    lines = text.split("\n")
-    cleaned_lines = []
-    for line in lines:
-        stripped = line.lstrip()
-        if stripped.startswith("- "):
-            cleaned_lines.append(stripped[2:])
-        elif stripped.startswith("* "):
-            cleaned_lines.append(stripped[2:])
-        else:
-            cleaned_lines.append(stripped)
-    cleaned = "\n".join(cleaned_lines)
-
-    # 원본 + 클린 버전 둘 다 시도
-    for target in [text, cleaned]:
-        patterns = [
-            r"```json\s*(.*?)```",
-            r"```\s*(.*?)```",
-            r"(\{.*\})",
-        ]
-        for pattern in patterns:
-            match = re.search(pattern, target, re.DOTALL)
-            if match:
-                try:
-                    return json.loads(match.group(1).strip())
-                except json.JSONDecodeError:
-                    continue
-    return None
-
-
 async def select_best_candidate(
     topic_results: list[dict[str, Any]],
     analysis: dict[str, Any],

src/pipeline.py

@@ -36,6 +36,7 @@ from src.image_utils import get_image_sizes, embed_images
 from src.space_allocator import calculate_container_specs
 from src.slide_measurer import measure_rendered_heights, capture_slide_screenshot
 from src.config import settings
+from src.json_utils import parse_json as _parse_json
 
 logger = logging.getLogger(__name__)
 
@@ -2080,20 +2081,3 @@ def _convert_kei_judgment(
             new_adjs.append(adj)
 
     review_result["adjustments"] = new_adjs
-
-
-def _parse_json(text: str) -> dict[str, Any] | None:
-    """텍스트에서 JSON을 추출한다."""
-    patterns = [
-        r"```json\s*(.*?)```",
-        r"```\s*(.*?)```",
-        r"(\{.*\})",
-    ]
-    for pattern in patterns:
-        match = re.search(pattern, text, re.DOTALL)
-        if match:
-            try:
-                return json.loads(match.group(1).strip())
-            except json.JSONDecodeError:
-                continue
-    return None

tests/test_json_utils.py

@@ -0,0 +1,55 @@
+"""Unit tests for ``src.json_utils.parse_json``.
+
+IMP-28 L4 — `_parse_json` dedup unit u2.
+
+Pins the shared helper semantics that previously lived in
+content_editor.py / design_director.py / kei_client.py (fuller form) and
+pipeline.py (simple form). The fuller form is a strict superset of the
+simple form; these tests cover both axes.
+"""
+from __future__ import annotations
+
+from src.json_utils import parse_json
+
+
+def test_parse_json_fenced_json_block():
+    text = 'prefix\n```json\n{"a": 1, "b": "x"}\n```\nsuffix'
+    assert parse_json(text) == {"a": 1, "b": "x"}
+
+
+def test_parse_json_plain_fenced_block():
+    text = 'prefix\n```\n{"x": 2}\n```\nsuffix'
+    assert parse_json(text) == {"x": 2}
+
+
+def test_parse_json_bare_braces():
+    text = 'noise before {"y": 3, "z": [1, 2]} noise after'
+    assert parse_json(text) == {"y": 3, "z": [1, 2]}
+
+
+def test_parse_json_list_prefix_dash_cleanup():
+    text = '- {"b": 4}'
+    assert parse_json(text) == {"b": 4}
+
+
+def test_parse_json_list_prefix_star_cleanup():
+    text = '* {"c": 5}'
+    assert parse_json(text) == {"c": 5}
+
+
+def test_parse_json_no_json_returns_none():
+    assert parse_json("no json here at all") is None
+
+
+def test_parse_json_malformed_returns_none():
+    assert parse_json("{ invalid json") is None
+
+
+def test_parse_json_prefix_free_no_op():
+    text = '{"d": 6}'
+    assert parse_json(text) == {"d": 6}
+
+
+def test_parse_json_fenced_preferred_over_bare_braces():
+    text = 'outer {"outer": true} ```json\n{"inner": 1}\n```'
+    assert parse_json(text) == {"inner": 1}