feat: add prompt loading pipeline and path validator

- Add read_repo_instructions() to read both AGENTS.md and CLAUDE.md
- Add path_validator.validate_paths() for writable/blocked path enforcement
- Add 10 passing tests (test_prompt_loading.py, test_path_validator.py)
- All 71 tests pass

agent/utils/agents_md.py

@@ -32,3 +32,41 @@ async def read_agents_md_in_sandbox(
     content = result.output or ""
     content = content.strip()
     return content or None
+
+
+async def read_repo_instructions(
+    sandbox_backend: SandboxBackendProtocol,
+    repo_dir: str,
+) -> str:
+    """AGENTS.md와 CLAUDE.md를 모두 읽어서 프롬프트에 주입할 문자열을 반환한다."""
+    sections = []
+
+    agents_md = await _read_file_if_exists(sandbox_backend, f"{repo_dir}/AGENTS.md")
+    if agents_md:
+        sections.append(f"## Repository Agent Rules\n{agents_md}")
+
+    claude_md = await _read_file_if_exists(sandbox_backend, f"{repo_dir}/CLAUDE.md")
+    if claude_md:
+        sections.append(f"## Project Conventions\n{claude_md}")
+
+    return "\n\n".join(sections)
+
+
+async def _read_file_if_exists(
+    sandbox_backend: SandboxBackendProtocol,
+    file_path: str,
+) -> str | None:
+    """파일이 존재하면 내용을 읽고, 없으면 None을 반환한다."""
+    safe_path = shlex.quote(file_path)
+    try:
+        loop = asyncio.get_event_loop()
+        result = await loop.run_in_executor(
+            None,
+            sandbox_backend.execute,
+            f"test -f {safe_path} && cat {safe_path}",
+        )
+        if result.exit_code == 0 and result.output.strip():
+            return result.output.strip()
+    except Exception:
+        logger.debug("Failed to read %s", file_path)
+    return None

agent/utils/path_validator.py

@@ -0,0 +1,40 @@
+"""파일 경로 접근 제어."""
+from __future__ import annotations
+
+
+def validate_paths(
+    changed_paths: list[str],
+    writable: list[str],
+    blocked: list[str],
+) -> list[str]:
+    """변경된 파일 경로들을 검증한다.
+
+    Args:
+        changed_paths: 변경된 파일 경로 목록.
+        writable: 쓰기 허용 경로 접두사 목록.
+        blocked: 차단 경로 목록 (정확 일치 또는 접두사).
+
+    Returns:
+        위반 사항 메시지 목록. 빈 리스트이면 모든 경로 통과.
+    """
+    errors: list[str] = []
+
+    for path in changed_paths:
+        normalized = path.lstrip("./")
+
+        blocked_match = False
+        for b in blocked:
+            b_normalized = b.lstrip("./")
+            if normalized == b_normalized or normalized.startswith(b_normalized + "/"):
+                errors.append(f"BLOCKED: '{path}' is in blocked_paths ({b})")
+                blocked_match = True
+                break
+
+        if blocked_match:
+            continue
+
+        is_writable = any(normalized.startswith(w.lstrip("./")) for w in writable)
+        if not is_writable:
+            errors.append(f"NOT_WRITABLE: '{path}' is not in writable_paths")
+
+    return errors

tests/test_path_validator.py

@@ -0,0 +1,68 @@
+import pytest
+from agent.utils.path_validator import validate_paths
+
+
+def test_valid_backend_path():
+    errors = validate_paths(
+        ["backend/app/services/rebalance.py"],
+        writable=["backend/app/", "backend/tests/"],
+        blocked=[".env", "quant.md"],
+    )
+    assert errors == []
+
+
+def test_valid_multiple_paths():
+    errors = validate_paths(
+        [
+            "backend/app/api/signal.py",
+            "backend/tests/unit/test_signal.py",
+            "frontend/src/app/page.tsx",
+            "docs/README.md",
+        ],
+        writable=["backend/app/", "backend/tests/", "frontend/src/", "docs/"],
+        blocked=[".env"],
+    )
+    assert errors == []
+
+
+def test_blocked_path_rejected():
+    errors = validate_paths(
+        [".env", "backend/app/main.py"],
+        writable=["backend/app/"],
+        blocked=[".env", "quant.md"],
+    )
+    assert len(errors) == 1
+    assert ".env" in errors[0]
+
+
+def test_non_writable_path_rejected():
+    errors = validate_paths(
+        ["docker-compose.prod.yml"],
+        writable=["backend/app/"],
+        blocked=[],
+    )
+    assert len(errors) == 1
+
+
+def test_quant_md_blocked():
+    errors = validate_paths(
+        ["quant.md"],
+        writable=["backend/app/", "docs/"],
+        blocked=["quant.md"],
+    )
+    assert len(errors) == 1
+    assert "quant.md" in errors[0]
+
+
+def test_empty_paths_ok():
+    errors = validate_paths([], writable=["backend/app/"], blocked=[".env"])
+    assert errors == []
+
+
+def test_alembic_versions_writable():
+    errors = validate_paths(
+        ["backend/alembic/versions/001_add_table.py"],
+        writable=["backend/alembic/versions/"],
+        blocked=[],
+    )
+    assert errors == []

tests/test_prompt_loading.py

@@ -0,0 +1,58 @@
+import pytest
+from unittest.mock import MagicMock
+from dataclasses import dataclass
+
+
+@dataclass
+class FakeExecuteResponse:
+    output: str
+    exit_code: int = 0
+
+
+@pytest.fixture
+def mock_sandbox():
+    sandbox = MagicMock()
+    return sandbox
+
+
+@pytest.mark.asyncio
+async def test_reads_agents_md_and_claude_md(mock_sandbox):
+    def fake_execute(cmd, **kwargs):
+        if "AGENTS.md" in cmd:
+            return FakeExecuteResponse(output="# AGENTS.md\n## Rules\n- rule 1", exit_code=0)
+        if "CLAUDE.md" in cmd:
+            return FakeExecuteResponse(output="# CLAUDE.md\n## Overview\n- info 1", exit_code=0)
+        return FakeExecuteResponse(output="", exit_code=1)
+
+    mock_sandbox.execute = MagicMock(side_effect=fake_execute)
+
+    from agent.utils.agents_md import read_repo_instructions
+    result = await read_repo_instructions(mock_sandbox, "/workspace/galaxis-po")
+    assert "Rules" in result
+    assert "Overview" in result
+
+
+@pytest.mark.asyncio
+async def test_agents_md_only(mock_sandbox):
+    def fake_execute(cmd, **kwargs):
+        if "AGENTS.md" in cmd:
+            return FakeExecuteResponse(output="# AGENTS rules", exit_code=0)
+        return FakeExecuteResponse(output="", exit_code=1)
+
+    mock_sandbox.execute = MagicMock(side_effect=fake_execute)
+
+    from agent.utils.agents_md import read_repo_instructions
+    result = await read_repo_instructions(mock_sandbox, "/workspace/galaxis-po")
+    assert result is not None
+    assert "AGENTS" in result
+
+
+@pytest.mark.asyncio
+async def test_no_instruction_files(mock_sandbox):
+    mock_sandbox.execute = MagicMock(
+        return_value=FakeExecuteResponse(output="", exit_code=1)
+    )
+
+    from agent.utils.agents_md import read_repo_instructions
+    result = await read_repo_instructions(mock_sandbox, "/workspace/galaxis-po")
+    assert result == ""