Lease Safe

Lease Safe(전월세안전내비) is a PlayMCP-compatible remote MCP server for Korean lease, jeonse, wolse, and moving-safety guidance.

It uses official public data and reviewed official guidance to help users:

• run a one-shot lease safety assessment that combines rent market, sale market, red flags, and next actions
• convert a region name into official legal-dong codes through the official legal-dong API
• compare nearby reported rent deposits when a data.go.kr API key is configured
• compare a deposit against nearby sale prices to estimate sale-price-to-deposit risk
• detect contract red flags without making legal conclusions
• plan move-in protection steps such as move-in report, fixed date, and lease report
• prepare questions for landlords, agents, and official institutions
• route users to Government24, RTMS, Internet Registry Office, HUG, and lease dispute mediation paths
• summarize common lease-dispute prevention steps

PlayMCP Fit

• Streamable HTTP transport: POST /mcp
• Stateless server
• Tool count: 10
• No kakao string in server or tool names
• Required tool annotations included
• Compact Korean markdown outputs
• Dockerfile included for PlayMCP in KC Git source build
• GitHub Actions CI runs secret scan, tests, PlayMCP validation, local MCP HTTP smoke, MCP boundary rejection smoke, rate-limit smoke, production dependency audit, linux/amd64 Docker build, and Docker runtime smoke

Data Sources

Automatic data:

• 행정안전부 행정표준코드 법정동코드 OpenAPI
• 국토교통부 아파트, 연립다세대, 단독/다가구, 오피스텔 전월세 실거래가 OpenAPI
• 국토교통부 아파트, 연립다세대, 단독/다가구, 오피스텔 매매 실거래가 OpenAPI

Reviewed official guidance:

• 정부24
• 부동산거래관리시스템 RTMS
• 인터넷등기소
• 법제처 찾기쉬운 생활법령
• 국가법령정보센터
• 한국부동산원·LH 임대차분쟁조정위원회
• HUG 주택도시보증공사
• 국세청
• 위택스

DATA_GO_KR_SERVICE_KEY is required for API-backed tools: assess_lease_safety, resolve_legal_dong_code, compare_rent_market, and compare_deposit_to_sale_market. Encoded and decoded data.go.kr keys are both accepted. Missing keys, placeholder values, whitespace, malformed percent-encoding, short or syntactically invalid keys, or data.go.kr rejections fail clearly instead of using fake sample data.

Flagship Tool

assess_lease_safety is the primary tool to show in a demo. It takes housingType, lawdCd, dealYmd, depositManwon, and optional situation details, then returns:

• an overall risk level with explicit reasons
• nearby rent-market median and sample transactions
• nearby sale-market median and deposit-to-sale ratio
• contract red flags from the user's situation
• immediate official next actions for registry, move-in report, fixed date, lease report, and HUG checks
• official source links used for the assessment

Production Configuration

Production requires DNS rebinding protection:

MCP_ALLOWED_HOSTS=your.playmcp.host,your.custom.domain

Use unique plain hostnames only. Do not include https://, ports, paths, whitespace, wildcards, blank comma-separated entries, underscores, empty labels, or labels that start or end with -.

The HTTP bind host defaults to 0.0.0.0 for container runtimes. Set HOST=127.0.0.1 only for local or platform environments that require loopback binding.

Production also requires the official public-data key at startup because the flagship tool depends on live legal-dong, rent, and sale APIs:

DATA_GO_KR_SERVICE_KEY=your-data-go-kr-service-key

Production also requires bearer-token protection for MCP POST requests:

MCP_AUTH_TOKEN=replace-with-runtime-secret

It must be a real token, not a placeholder, at least 16 characters, free of whitespace, and visible ASCII only. In production, startup fails when MCP_AUTH_TOKEN is missing or blank. POST /mcp requires Authorization: Bearer <token>.

Optional request-size hardening is available for deployments with stricter ingress limits:

MCP_MAX_BODY_BYTES=262144

The default MCP request body limit is 262144 bytes, and the maximum accepted value is 1048576 bytes. Invalid or blank configured values fail at startup instead of silently changing runtime behavior.

Optional MCP request rate limiting is available for public deployments:

MCP_RATE_LIMIT_PER_MINUTE=120

The default MCP POST rate limit is 120 requests per client per minute, and the maximum accepted value is 10000. Set MCP_RATE_LIMIT_PER_MINUTE=0 to disable it when an upstream gateway already enforces stricter limits. Blank configured values fail at startup instead of falling back to the default.

Optional public-data timeout tuning is available when the deployment ingress has a tighter request budget:

PUBLIC_DATA_TIMEOUT_MS=8000

The default official public-data API timeout is 8000ms, with a maximum accepted value of 60000ms. Invalid or blank configured values fail before requests are made. CI and registration evidence runs set this to 30000ms because the official housing APIs can be slower while still returning valid data.

Run Locally

Use Node.js 20 or newer with npm 10 or newer. .npmrc enables engine-strict=true, so unsupported runtimes fail during npm ci. It also sets ignore-scripts=true, so dependency lifecycle scripts do not run during install.

npm ci --ignore-scripts
npm run build
MCP_ALLOWED_HOSTS=127.0.0.1,localhost npm start

MCP endpoint:

http://127.0.0.1:3000/mcp

Smoke:

MCP_ENDPOINT=http://127.0.0.1:3000/mcp npm run smoke

Remote PlayMCP endpoint smoke after registration:

MCP_ENDPOINT=https://<playmcp-host>/mcp MCP_AUTH_TOKEN=... npm run smoke:remote

Start a local server and run the MCP HTTP smoke in one command:

npm run smoke:http

Release preflight:

npm run preflight

npm run preflight runs working-tree, staged, and committed whitespace diff checks, secret scan, unit tests, PlayMCP validation, official source freshness validation with a 45-day reviewedAt gate, local MCP HTTP smoke with root route minimality, API-backed missing-key failure checks when DATA_GO_KR_SERVICE_KEY is absent, DNS-rebinding Host rejection, unsupported-method, invalid-JSON, unsupported-content-type, bearer-auth, malformed Content-Length, and oversized-request rejection checks, MCP rate-limit smoke, production dependency audit, linux/amd64 Docker build, Docker runtime smoke with image-platform evidence and the same MCP boundary checks, and live public-data smoke with extracted evidence-line validation when DATA_GO_KR_SERVICE_KEY is set.

Registration preflight:

DATA_GO_KR_SERVICE_KEY=... MCP_AUTH_TOKEN=... npm run preflight:registration

npm run preflight:registration runs the same checks but requires the live public-data smoke to run, pass for every supported housing type, and produce extractable registration evidence lines. Use it before PlayMCP registration.

For registration evidence in GitHub Actions, run the manual Registration Preflight workflow after adding DATA_GO_KR_SERVICE_KEY and MCP_AUTH_TOKEN as repository secrets. Unlike the normal CI workflow, this workflow fails instead of skipping when registration secrets are missing.

Final registration readiness gate:

npm run check:registration-readiness

npm run check:registration-readiness fails unless the worktree is clean, local HEAD matches the remote main HEAD, DATA_GO_KR_SERVICE_KEY and MCP_AUTH_TOKEN exist as GitHub repository secrets, the latest CI run for that commit on main completed successfully with every required Quality Gate evidence step passed, including official source freshness, Docker build/runtime, live public-data smoke, and Publish live public-data status, and the manual Registration Preflight workflow completed successfully for the same commit with its evidence summary published inside the Registration Evidence job. It reads only GitHub secret names and workflow metadata, never secret values.

Live public-data smoke before production rollout:

DATA_GO_KR_SERVICE_KEY=... npm run smoke:public-data

By default, the live public-data smoke checks legal-dong lookup, rent-market APIs for all four housing types, sale-market APIs for all four housing types, and the flagship one-shot assessment for every selected housing type using the high-risk demo concerns from the submission pack. Successful registration evidence includes a legal_dong=ok lawd_cd=... line that must match the configured LAWD code, plus rent_market[...], sale_market[...], and lease_assessment[...] log lines for every selected housing type, with positive sample counts, official totalCount evidence, and risk_level=high or risk_level=very_high for the flagship demo assessment.

Optional overrides:

PUBLIC_DATA_SMOKE_REGION="서울 관악구" PUBLIC_DATA_SMOKE_LAWD_CD=11620 PUBLIC_DATA_SMOKE_DEAL_YMD=202605 DATA_GO_KR_SERVICE_KEY=... npm run smoke:public-data

To narrow the live smoke while debugging one source:

PUBLIC_DATA_SMOKE_HOUSING_TYPES=apartment,rowhouse DATA_GO_KR_SERVICE_KEY=... npm run smoke:public-data

Do not use a narrowed PUBLIC_DATA_SMOKE_HOUSING_TYPES list as registration evidence. npm run preflight:registration fails unless all supported housing types are included, and blank or empty comma-separated entries such as apartment, are rejected instead of being normalized.

CI Gate

The repository includes .github/workflows/ci.yml for main. It runs:

• npm ci --ignore-scripts
• npm test
• npm run scan:secrets
• npm run validate:playmcp
• npm run check:sources
• npm run smoke:http
• npm run smoke:rate-limit
• npm audit --omit=dev
• docker build --platform linux/amd64 -t lease-safe-mcp-ci .
• npm run smoke:docker

If the GitHub repository has a DATA_GO_KR_SERVICE_KEY secret, CI also runs the live public-data smoke against all supported housing types in registration mode and publishes the official source freshness gate, required housing coverage, and extracted live public-data evidence lines in the job summary. Without that secret, the live API smoke is skipped and local pre-submission smoke should be run with the key.

The Publish Image workflow publishes the verified container to GHCR after CI succeeds on main, and can also be dispatched manually. It builds linux/amd64, runs Docker runtime smoke before registry login and push, then publishes:

• Immutable image: ghcr.io/hjongc/lease-safe-mcp:sha-<short-sha>
• Moving main image: ghcr.io/hjongc/lease-safe-mcp:main

Use the immutable sha-<short-sha> tag for PlayMCP registration evidence. If PlayMCP cannot pull private GHCR packages, make the package public or deploy the same image to a runtime that can authenticate to GHCR.

Submission Checklist

Before registering in PlayMCP:

• Review SECURITY.md
• Review docs/submission.md
• Review docs/operations.md
• Run npm run preflight:registration locally with DATA_GO_KR_SERVICE_KEY and MCP_AUTH_TOKEN set
• Run npm run check:github-secret and confirm the GitHub repository secrets exist before trusting CI live-smoke evidence
• Run the manual GitHub Actions Registration Preflight workflow on the submitted commit
• Confirm the latest GitHub Actions CI run is green
• Confirm GitHub Actions live public-data smoke is passed, not skipped
• Confirm the GitHub Actions Publish Image workflow succeeded for the submitted commit and use its immutable GHCR image tag
• Run npm run check:registration-readiness on a clean worktree to verify the current commit has passing CI and Registration Preflight evidence
• Prefer the normal sha-<short-sha> image when PlayMCP exposes runtime secret settings for the submitted image
• If PlayMCP has no runtime secret/header settings, use the separate playmcp-sha-<short-sha> baked image from the Publish Image workflow
• The PlayMCP baked image includes DATA_GO_KR_SERVICE_KEY at build time and runs with MCP_AUTH_MODE=playmcp-untrusted-public, so bearer authentication and host allowlist enforcement are disabled only for that image
• For normal production images, configure the same DATA_GO_KR_SERVICE_KEY and a production MCP_AUTH_TOKEN as runtime environment variables or secrets
• For normal production images, set MCP_ALLOWED_HOSTS to the PlayMCP host or deployment domain
• After PlayMCP issues the HTTPS endpoint, run MCP_ENDPOINT=https://<playmcp-host>/mcp MCP_AUTH_TOKEN=... npm run smoke:remote for normal authenticated deployments; for the baked PlayMCP image, use MCP_ENDPOINT=https://<playmcp-host>/mcp npm run smoke
• Use assess_lease_safety as the demo entry tool

Do not bake secrets into the image for normal production deployments with Dockerfile ENV, build args, committed files, or hardcoded source. The only exception is the separate PlayMCP baked image produced from GitHub Actions repository secrets because PlayMCP does not provide runtime secret/header settings; treat it as a contest-only public endpoint image and rotate DATA_GO_KR_SERVICE_KEY after the event.

For long-lived production, the safer fallback remains a secret-capable external HTTPS endpoint registered in PlayMCP instead of the baked contest image.

PlayMCP in KC Git-source build:

• Git URL: https://github.com/hjongc/lease-safe-mcp.git
• Branch/ref: main
• Dockerfile path: Dockerfile
• PAT: empty if the repository is public