--- name: dirextalk-deployer description: Deploy, resume, verify, update, recover, reset, or destroy production Dirextalk services and nodes on AWS, and wire local agent runtimes. Use when the user explicitly invokes `$dirextalk-deployer` or asks in natural language to deploy, update, repair, verify, resume, reset, or destroy a Dirextalk service or node. --- # Dirextalk Deployer This skill is the compact agent-facing entrypoint. Treat this repository root as the execution engine and read the referenced docs only when that phase needs detail. Entrypoints: ```text scripts/orchestrate.sh scripts/destroy.sh scripts/update.sh scripts/reset-app-data.sh ``` ## Freshness Gate On Windows, this check comes first, including before skill installation or refresh. Run it from Git Bash: ```bash case "$(uname -s)" in MINGW*) git_root=$(git --exec-path 2>/dev/null | sed 's#/mingw64/libexec/git-core$##'); command -v git >/dev/null && command -v cygpath >/dev/null && git --version | grep -q '\.windows\.' && [ -n "$git_root" ] && [ "$(cygpath -m "${EXEPATH:-}" | tr '[:upper:]' '[:lower:]')" = "$(printf '%s/bin' "$git_root" | tr '[:upper:]' '[:lower:]')" ] ;; Linux*|Darwin*) true ;; *) false ;; esac ``` Continue only when that command succeeds. Native Linux, macOS, and WSL sessions use their own Bash environment directly. On native Windows, it verifies that the current shell's `EXEPATH` is under the same Git for Windows installation as `git`, and rejects PowerShell, MSYS2, and Cygwin. Otherwise tell the Windows user to install Git for Windows from `https://git-scm.com/download/win`, reopen Git Bash, and stop. The skill CLI repeats and strengthens the Windows gate before `install`, `update`, or `refresh` can write a target. Before deployment, repair, verification, teardown, runtime wiring, or skill installation, make one freshness attempt: ```bash npm install -g dirextalk-deployer@latest dirextalk-deployer skill refresh --agent ``` Use project scope only when the user explicitly asks for repository-local installation: ```bash dirextalk-deployer skill refresh --agent --scope project --project ``` If npm is unavailable, report that freshness could not be checked and continue with the local copy. If the user asks to install from `YingSuiAI/dirextalk-deployer`, do not use a generic GitHub skill installer; read the README and follow the npm install rule. Use a Git clone only for deployer development or local patching. ## Platform Law Classify every path by consumer before writing it to `state.json`, `credentials.json`, `dirextalk-connect/config.toml`, docs, or printed commands: - Remote server paths are Linux paths consumed on EC2, such as `/var/dirextalk-message-server`. - Deployer execution paths may be POSIX paths inside Bash phases. - Local bridge paths are consumed by `dirextalk-connect` and local agent processes. On Windows they must be Windows-compatible paths. - Documentation paths must be portable examples using `$HOME`, `%USERPROFILE%`, `$env:USERPROFILE`, ``, or ``. Windows, Linux, macOS, and WSL users run the same Bash entrypoints. A process running inside WSL is a Linux deployment host and uses its distribution's Node.js, AWS CLI, paths, and Bash directly. On native Windows, Git for Windows is required: use the exact preflight above before any deployment action. If it fails, tell the user to install Git for Windows from `https://git-scm.com/download/win`, open **Git Bash**, and rerun; do not substitute PowerShell or launch WSL as a command runner for a Windows-owned deployment. Git Bash automatically writes native `C:/...` paths for Windows-native Node.js, `dirextalk-connect`, and agent processes. Run every lifecycle action from that same Git Bash session: ```bash DOMAIN= bash scripts/orchestrate.sh ``` The deployer explicitly normalizes file paths passed to native Node.js, AWS CLI, curl, and local agent tools. It does not depend on implicit MSYS argument conversion, so a parent runtime that sets `MSYS_NO_PATHCONV=1` cannot turn a Git Bash `/c/...` or `/tmp/...` path into an unrelated `C:\c\...` or `C:\tmp\...` lookup. Keep each local service in one environment: either native WSL/Linux paths or native Windows Git Bash paths. Do not switch the same service directory between PowerShell, WSL, and Git Bash. ## Prerequisites And Confirmation Do not deploy until the user has an active AWS account, a real long-lived domain, AWS credentials, DNS authority, and billing acknowledgement. For first-time users, guide them step by step. Do not front-load the whole cloud setup checklist. Ask only the next blocking question, wait for the user's answer or completion, then continue to the next step. Default tone for new users: - Use product language such as account, domain, access key file, DNS provider, server, fixed IP, and monthly AWS cost. - Avoid technical labels such as EC2, EIP, IAM policy, security group, EBS, Matrix `server_name`, Route53 hosted zone, federation identity, or TURN unless the user asks what they mean or the term appears in an AWS screen they must operate. - When a technical term is unavoidable, explain it in one short sentence before asking the user to act. - Never give a long architecture explanation during onboarding unless the user explicitly asks why the step is needed. Step-by-step onboarding flow: 1. **AWS account.** - Shortcut: if the user already provided valid AWS credentials, such as a configured profile or a CSV that passed `aws sts get-caller-identity`, skip browser sign-in and email questions. The agent already has AWS access. - Ask: "Do you already have an AWS account you can log into?" - If yes, continue to the access key step. - If no, ask the user to open `https://signin.aws.amazon.com/signup?request_type=register`, register in their browser, complete payment/phone verification and Basic support selection if AWS asks, then stop until they say the account is ready. - Never ask for, collect, paste, log, or store payment card details, root password, MFA code, email verification code, or phone verification code. 2. **AWS access key or profile.** - Ask: "Do you already have an AWS access key CSV file or AWS profile for deployment?" - If yes, ask only for the local CSV path or profile name, then verify it. - If no, offer two credential paths and ask the user to choose: 1. **Root access key (default fastest path):** simpler to create for a first deployment because it uses the account owner identity directly. Explain that it is highly privileged, must be saved securely, must never be pasted into chat or committed, and should be rotated or deleted after deployment. 2. **Dedicated IAM deployment user:** safer because it avoids root keys, but requires more AWS console steps. Explain in one sentence: "This temporary `DirextalkDeployer` user with `AdministratorAccess` lets the deployment tool create and later destroy this Dirextalk node; delete or disable it after deployment." - Root access keys are allowed when the operator explicitly chooses them. Do not block deployment only because STS returns a root ARN; report `root=true`, repeat the security warning once, and continue if the user accepts that risk. - Prefer the repository helper for CSV import and redacted verification: ```bash bash scripts/aws-credentials.sh import-csv /path/to/accessKeys.csv dirextalk-deployer export AWS_PROFILE=dirextalk-deployer bash scripts/aws-credentials.sh verify dirextalk-deployer ``` - The agent may read the local CSV path, but must never print the Access Key ID together with the Secret Access Key, and must never write secrets into the repository, skill files, logs, or chat output. 3. **Domain.** - Ask: "Do you already own a long-lived domain or subdomain you want to use for this Dirextalk node?" - If yes, ask for the domain. - If no, first check whether the AWS account already has Route53 registered domains when AWS CLI access is available: ```bash aws route53domains list-domains --profile ``` If domains exist, present only the domain names and ask whether to use one. If none exist, ask the user to buy or prepare a domain, then stop until they have it. - Do not ask where DNS is managed. After AWS credentials are available, the deployer checks for the longest matching public Route53 hosted zone in the current AWS account. If one exists it manages the A record automatically; otherwise it continues with external DNS and asks for the A record only after the fixed public IP exists. - Explain only this much by default: "Use a real long-term domain because changing it later means creating a new chat server identity." - Do not use localhost, raw IP addresses, wildcard domains, disposable domains, temporary `sslip.io`, or other throwaway names for production. 4. **DNS control.** - Let S2 query public Route53 hosted zones before asking any DNS-management question. A matching zone selects `DOMAIN_MODE=route53`; no matching zone selects `DOMAIN_MODE=user` without blocking infrastructure creation. - If Route53 listing fails, stop with an AWS credential/IAM error. Never misclassify an API failure as externally managed DNS. - For external DNS, wait until the script emits the fixed IP, then ask the user to create exactly: ```text A ``` - If the user prefers Route53 while the domain is registered elsewhere, the hosted zone and NS delegation must be prepared explicitly first. The user or a provider-specific DNS connector must delegate those NS records at the current registrar before authoritative DNS can resolve. 5. **Billing confirmation.** - Give a short billing warning before the first mutating AWS command: "This will create paid AWS resources for the server. They keep billing until destroyed." - Provide an upfront monthly estimate for the selected region and cloud provider before asking for final approval. Use the pricing helper output; do not invent a fixed quote from memory. - Tell the operator that new AWS customer accounts generally receive `100-200 USD` in free credits, and that users who have not used Lightsail generally receive three months of free Lightsail usage. Coverage is account-specific; recommend an AWS Budget and AWS Billing Console review, and say AWS official real-time policy prevails. - Check EC2-VPC Elastic IP quota before mutating AWS resources. For explicit EC2, also check default VPC, EC2 vCPU quota, and AMI availability. Before final deployment confirmation: ```bash aws lightsail get-regions --include-availability-zones --output json bash scripts/pricing-estimate.sh --region --cloud-provider lightsail --domain-mode route53 bash scripts/pricing-estimate.sh --state ~/.dirextalk/nodes//state.json --write-state ``` Record and report `cost_estimate` and billing reminders. Tell the operator that new AWS customer accounts generally receive `100-200 USD` in free credits, and that users who have not used Lightsail generally receive three months of free Lightsail usage. Coverage is account-specific; recommend an AWS Budget, AWS Billing Console review, and say AWS official real-time policy prevails. Check EC2-VPC Elastic IP quota before mutating AWS resources. Required first-time deployment confirmation. Fill in the concrete domain, profile, region, and cloud provider. Include the AWS credit/Lightsail trial sentence immediately before asking for approval. Accept a natural-language confirmation in their own words; do not require them to copy a fixed sentence or a command token. Accept the confirmation only when it clearly covers all of the following: - the intended Dirextalk deployment and final domain; - the AWS profile or account authority and selected region/provider; and - acknowledgement that billable resources can remain billed until destroyed. Short replies such as "confirm", "deploy", or "go ahead" are sufficient only when the immediately preceding deployment summary already states those facts and the user has not changed the plan. Otherwise ask one concise follow-up that identifies the missing fact. Record the semantic user decision in the operation report, then set any required machine-only environment flags yourself. ```text Please confirm before I deploy. New AWS customer accounts generally receive 100-200 USD in free credits, and users who have not used Lightsail generally receive three months of free Lightsail usage. Credits and trials are account-specific, actual coverage must be verified in AWS Billing Console, and AWS official real-time policy prevails. For example: "I confirm deployment of in ; I authorize this AWS profile and understand the ongoing AWS charges." ``` If any prerequisite is missing, stop deployment and guide the user through that specific step before running `scripts/orchestrate.sh`. Required deployment env: ```bash DOMAIN= CONFIRM_DOMAIN_BINDING=1 DIREXTALK_CLOUD_PROVIDER=lightsail ``` Normal deployment consumes the deployer-owned production split release. Release preparation discovers the current application releases through `latest`, then records and deploys their stable `vX.Y.Z` image tags, source revisions, and real `--version` output. PostgreSQL/pgvector, Caddy, and coturn remain fixed dependencies, and the canonical runtime bundle is packaged with the deployer. The target host never clones a source repository and no mutable image override is part of the production path. The independent `YingSuiAI/dirextalk-updater` host binary is downloaded only on a verified Ubuntu 24.04+ x86_64 server with systemd >= 254 from the deployer-pinned Release URL and must match the deployer-pinned SHA-256. The local deployer host does not need Go and does not SCP updater artifacts. The updater pin and checksum contract remains independent from the default split release selection. Fresh deployment installs the updater control plane with its resident watchdog disabled. Authorized update/recovery jobs remain available and retain their own recovery behavior. The updater does not install or run a daily GitHub release-discovery timer. After the direct-version migration, an authorized client/server release action creates the target-version job instead. Leave `DOMAIN_MODE` unset for normal deployments. S2 automatically chooses `route53` only when the current AWS account contains a matching public hosted zone; otherwise it chooses `user` and gives manual A-record guidance after IP allocation. Explicit `DOMAIN_MODE=user|route53` remains an advanced automation override. If an existing Route53 A record points elsewhere, require an explicit semantic user confirmation that identifies the domain and the replacement target. Then set `DIREXTALK_CONFIRM_DNS_OVERWRITE=1` internally. If Route53 delegation is needed, wait for authoritative DNS before continuing. After the stable public IP exists, S3 revalidates the exact cloud instance, IP, AWS account, and SSH host, then runs authoritative and independent public- recursive DNS proof over SSH on that deployed host. Local `dig` output and `DNS_READY=1` are diagnostic only and cannot bypass this gate; Caddy/ACME host integration starts only after the remote proof succeeds. Default cloud provider is Lightsail. If no AWS region is configured in state, `AWS_DEFAULT_REGION`/`AWS_REGION`, or the AWS profile, the deployer recommends a default region from the local timezone and uses it in non-interactive runs; `DIREXTALK_DEFAULT_REGION` is the explicit deployer override. S1 queries Lightsail bundle availability and Lightsail availability zones before provisioning, but it does not query AWS Free Tier or credit usage. For manual Lightsail zone checks, use `aws lightsail get-regions --include-availability-zones --output json`; plain `aws lightsail get-regions` can omit availability-zone details. The default Lightsail zone is `a`; if it is unavailable, S1/S3 select another available Lightsail zone in the same region. If Lightsail has no usable bundle or availability zone in the selected region, S1 records an EC2 cost estimate but does not automatically switch to EC2; ask the operator to choose another Lightsail-capable region/zone or explicitly rerun with `DIREXTALK_CLOUD_PROVIDER=ec2` after reviewing the estimate. EC2 remains supported explicitly with `DIREXTALK_CLOUD_PROVIDER=ec2`; then S1 checks default VPC, EC2 vCPU quota, EC2-VPC Elastic IP quota, AMI availability, and S3 uses a 50 GiB gp3 root EBS volume. ## Local Runtime Wiring Read `references/agent-targets.md` before installing/updating this skill or wiring a runtime. Supported connect agents are: ```text acp antigravity claudecode codex copilot cursor devin gemini iflow kimi opencode pi qoder reasonix tmux ``` The supported local bridge is `dirextalk-connect`, installed from `dirextalk-connect@latest` by default or built from `https://github.com/YingSuiAI/dirextalk-connect.git`. The MCP tool surface is served by the deployed message server's HTTP MCP endpoint. S6 writes service-scoped files under `~/.dirextalk/nodes//`: ```text credentials.json dirextalk-connect/config.toml mcp/ ``` The dirextalk-connect config must use a direct Matrix config, create the Matrix session through `agent.matrix_session.create` with `agent_token`, require `@agent:`, and restrict sync/replies to the real `agent_room_id`. It must not use MCP credential-file environment variables. Key selectors: ```bash DIREXTALK_AGENT_PLATFORM=auto DIREXTALK_CONNECT_AGENT= DIREXTALK_AGENT_INSTALL=auto DIREXTALK_AGENT_INSTALL_MODE=recommended ``` `DIREXTALK_AGENT_INSTALL=auto` installs `dirextalk-connect@latest` into the current service directory, not into the npm global prefix, unless explicit binary/command overrides are set. MCP capability is declared independently from bridge-agent support and follows the effective connect agent: session (`acp`, Claude Code, Codex, Copilot, Gemini, Kimi, OpenCode, and Qoder), host-managed (Antigravity, Cursor, and iFlow), and unsupported (Devin, Pi, Reasonix, and tmux). Detected OpenClaw and Hermes hosts are always host-managed because their native registries own MCP. They require the ACP bridge; a non-ACP `DIREXTALK_CONNECT_AGENT` override fails closed. To bridge directly to Codex, select `DIREXTALK_AGENT_PLATFORM=codex` instead. Unsupported and unknown effective agents fail closed. The protocol vocabulary retains `project` and `conditional`, but no current connect backend uses them. S6 never generates a generic fallback artifact. Dedicated manual artifacts are limited to registry entries that name one; no unconsumed MCP env artifact is generated. MCP does not need a local CLI, daemon, proxy, or listening port. When refreshing an existing service-scoped package, S6 keeps the current daemon running during the npm operation and lets the final `daemon install --force` perform the short handoff; an npm failure must not stop the working daemon. S6 installs the service-scoped `dirextalk-connect` daemon and records it as installed only after `daemon status` reports Running and recent logs show `dirextalk-connect is running`; logs that show agent CLI missing, login/trust failures, ACP startup failures, or agent offline state fail S6 so deploy does not report success prematurely. `recommend` writes files and prints commands only; `skip` writes credentials and configs only. S6 no longer writes the retired service-level `env` file. Host-runtime artifacts remain reviewable even when the effective connect agent differs. For host-managed MCP, S6 omits all canonical MCP fields from connect agent options. With `DIREXTALK_AGENT_INSTALL=auto`, OpenClaw is registered through `openclaw config patch --stdin`, then must pass `openclaw mcp probe --json` before bridge startup. Its service token never appears in argv; inherited `OPENCLAW_CONFIG_PATH` and optional `DIREXTALK_OPENCLAW_PROFILE=` select the native scope. Hermes clones the current configured native profile into a marked service profile (or uses an explicit `DIREXTALK_HERMES_PROFILE`). An inherited `HERMES_HOME` that points back into the current node is replaced by the native Hermes home (`%LOCALAPPDATA%/hermes` on Windows, `$HOME/.hermes` elsewhere); use `DIREXTALK_HERMES_MCP_HOME` for a deliberate override. S6 stores the token through Hermes' native API, and requires a native live-tool probe. Both paths continue automatically only after their probe passes; no readiness flag is needed. Destroy removes the managed OpenClaw entry/token and any deployer-owned Hermes profile. Other host-managed backends without a safe native adapter record `operator_confirmed_host_managed`; only they use explicit `DIREXTALK_MCP_HOST_READY=1` confirmation. `recommend` and `skip` only write artifacts/guidance and retain `host_action_required` without running a host probe. Generated agent options write `mode = "yolo"` by default unless an explicit `mode` is supplied. On Windows, Cursor wiring uses `%LOCALAPPDATA%\cursor-agent\agent.cmd`. If Cursor Agent CLI is not logged in, the operator must run `agent.cmd login` once; rerunning the deployer refreshes config and restarts the service-scoped daemon. Explicit `DIREXTALK_CURSOR_COMMAND`, `DIREXTALK_CURSOR_AGENT_COMMAND`, `DIREXTALK_OPENCODE_COMMAND`, `DIREXTALK_CONNECT_AGENT_CMD`, `DIREXTALK_CURSOR_MODE`, and `DIREXTALK_CONNECT_AGENT_OPTIONS_TOML` overrides still win except where a host-owned OpenClaw/Hermes scope would be bypassed. Hermes writes `mcp/hermes.md` but stores its managed profile under the native Hermes home, so ACP and native registration share exactly one profile. The default service profile is cloned from the active configured profile, preserving model/provider authentication; an explicit `DIREXTALK_HERMES_PROFILE` remains user-owned and only its managed server entry is removed on destroy. S6 never writes a generic Hermes JSON file. State/report fields include `mcp_capability`, `mcp_config_dir`, `mcp_selected_config_type`, `mcp_selected_config`, token-free host-guidance fields such as `mcp_openclaw_config` and `mcp_hermes_config`, `mcp_transport`, `mcp_endpoint_url`, `credentials.status`, and `mcp.status`. Codex and Cursor do not receive standalone token-bearing MCP artifacts. Session injection is owned by dirextalk-connect; Cursor remains host-managed. ## Deployment Completion A new deployment is complete when S0-S7 are green, the App domain and eight-digit app initialization code are ready for delivery, dirextalk-connect is wired to the real `agent_room_id`, and the automated runtime/MCP checks pass. The runtime checks cover the service-scoped connect daemon, HTTP MCP initialization, tool discovery, and a read-only tool call. Agent/MCP validation is non-polluting and does not auto-send a normal chat message. App initialization and a user's first real chat are subsequent product usage, not deployer gates. Do not ask the user to return and confirm them, and do not run a separate `confirm` command after deployment. Runtime verification commands: ```bash DOMAIN= bash scripts/orchestrate.sh verify connect_daemon DOMAIN= bash scripts/orchestrate.sh verify mcp_doctor DOMAIN= bash scripts/orchestrate.sh verify mcp_smoke DOMAIN= bash scripts/orchestrate.sh verify mcp_tools DOMAIN= bash scripts/orchestrate.sh verify runtime ``` Final delivery runs `verify runtime` automatically and requires `runtime_checks.summary.status=passed`. If a check fails, repair it and resume the same deployment; successful delivery needs no post-deployment action in the deployer. ## Status, Reports, And Delivery When blocked or failed, run `bash scripts/orchestrate.sh status` for the current service and reflect the Recovery summary: - Where it is blocked. - Billing impact. - Resume safety. - Local refresh: if refresh is pending, rerun the deployment workflow to refresh S4-S7, local credentials, MCP snippets, automatic installs, and runtime checks. - Next action. - Stop-loss. Operation reports are written as redacted `operation-report.json` artifacts. `scripts/orchestrate.sh report new_deploy` can regenerate a new deployment report. Reports must not include AWS secrets, access tokens, agent tokens, Matrix session tokens, or the eight-digit app initialization code. Reports include automated phase and runtime-check evidence, `destroy.evidence`, `credentials.status`, `mcp.status`, `possible_remaining_billable_resources`, AWS resource IDs, EBS root volume evidence, the default 50 GiB gp3 root EBS volume size, billing reminders, and `cost_estimate`. Delivery must include App domain, eight-digit app initialization code, deployment completion status, `agent_room_id`, service directory, dirextalk-connect config, MCP config paths, Matrix bridge user/device, AWS region, cloud provider, cloud instance/public IP, SSH path, state path, report path, AWS credit/Lightsail trial reminder, AWS official policy reminder, AWS Billing Console verification reminder, stop-billing reminder, and security reminder to delete or disable temporary credentials and rotate/remove root access keys if used. ## Update, Reset, And Destroy `update.sh` reads the remote root-owned split receipt as the current application-version authority, then binds controlled linux/amd64 release identities and invokes the receipt-bound canonical split wrapper directly over the verified SSH host. Thus an App-initiated upgrade may be ahead of local state without blocking a later direct update. It does not use an owner access token or the server release API. Message Server and Agent can be advanced together or independently; an Agent update additionally requires `DIREXTALK_AGENT_VERSION` and `DIREXTALK_AGENT_MINIMUM_SERVER_VERSION`. Arbitrary image overrides remain unsupported. Use `DOMAIN= bash scripts/update.sh` to update an existing production split node. It stages the current helpers and runs the receipt-bound canonical reconcile path. On host reboot, the installed `dirextalk-split-recovery.service` runs after Docker and restores only the receipt-bound Agent runtime while preserving the exact healthy Message Server; do not replace it with ad hoc Compose commands. Treat remote operation results as three states: `0` means Message Server and Agent are healthy, `3` preserves healthy messaging/Edge/bootstrap while Agent needs attention, and `1` is a fatal Message Server, infrastructure, identity, or contract failure. Read `references/verification-recovery.md` before manual reconcile or reboot recovery, and close the operation only after its identity, cgroup, health, and persistence gates pass. Use `bash scripts/reset-app-data.sh` only after an explicit semantic user confirmation that application data will be cleared. Set `DIREXTALK_RESET_APP_DATA_CONFIRM=1` internally; never make the user copy it. It preserves the cloud instance, fixed public IP/static IP or Elastic IP, DNS, and Caddy TLS storage, clears application data, clears stale credential/runtime-check evidence, sets `connect_install_status=refresh_pending`, marks local refresh pending, and stops only the matching service-scoped dirextalk-connect daemon. The follow-up orchestrate run regenerates credentials and MCP snippets. Destroy uses `bash scripts/destroy.sh` on every supported local host. Require a clear natural-language user instruction to destroy or cancel the named service; do not require a copied confirmation string. Destroy uses the same AWS identity boundary as deployment. Root AWS access-key identity is allowed when the operator explicitly chose it. Destroy stops and uninstalls only the service-scoped daemon whose WorkDir matches `~/.dirextalk/nodes//dirextalk-connect`, then removes recorded AWS resources and writes `destroy.evidence`. If `possible_remaining_billable_resources` is present, AWS Console/Billing is the source of truth and cleanup must continue. ## References - Tool setup: `references/tooling.md` - Agent targets: `references/agent-targets.md` - Deployment workflow, confirmations, pricing, and DNS: `references/deployment-workflow.md` - Runtime wiring: `references/runtime-wiring.md` - Verification and recovery: `references/verification-recovery.md` - State machine: `references/state-machine.md` - Architecture and troubleshooting: `references/architecture.md`, `references/troubleshooting.md` - Windows notes: `references/windows-deployment-notes.md` - Token refresh/update/reset: `references/token-refresh.md`