version: "1.0.1" name: Service Creator description: Guide for creating background monitoring services that can proactively notify users

Service Creator Skill

This skill guides you on how to create background services that monitor data and proactively notify users.

Reference documents directory: {{SKILL_DIR}}/reference/

When you need detailed information on a specific topic below, use read_file to load the corresponding reference document. Do NOT read all references upfront — only load what you need for the current step.

When to Use

Create a service when the user asks you to:

• Monitor something continuously (stocks, websites, APIs, files, etc.)
• Get notified when certain conditions are met
• Run periodic checks or tasks
• Watch for changes or events

Examples of user requests:

• "Help me monitor XX stock, notify me if it drops more than 5%"
• "Watch this API endpoint and tell me when it returns data"
• "Check my server status every 5 minutes"
• "Monitor this folder for new files"

Architecture Overview

Services use a two-layer filtering pattern: Local Rules Filter → Invoke API (LLM Evaluation). Read reference/architecture.md for full details when designing filter logic.

Service Creation Workflow

Step 0: Runtime Availability Check (Automatic)

When you call service_create, the system automatically checks if the required runtime (Node.js or Python) is available. If not available, the tool returns an error.

When runtime is missing:

1. Ask the user if they want you to install it
2. If yes, try to install using methods that DON'T require sudo:

• macOS: Use Homebrew (brew install node / brew install python3) - no sudo needed
• If no Homebrew: Install Homebrew first, or use nvm/pyenv
• Linux/Windows: Explain to user that installation requires manual steps (sudo password or admin rights)

1. After installation succeeds, retry service_create

Note: You cannot use sudo or su commands as they require password interaction. Only use installation methods that work without elevated privileges.

Step 1: Create Service Metadata

Use the service_create tool with:

• name: Human-readable name
• description: What the service does
• type: Choose based on whether the task has a definite end:
• "longRunning": Never exits, runs indefinitely (e.g., "monitor stock price every 30s", "wake me up every day at 8am", "send weekly report every Monday")
• "scheduled": Completes and exits after task is done (e.g., "remind me at 4:30pm today", "remind me to drink water 3 times", "notify me tomorrow morning")
• runtime: "node" or "python"
• entryFile: Entry file name (e.g., "index.js" or "main.py")
• schedule: For scheduled services, interval like "*/5" (every 5 minutes)
• userRequest: The user's original request (verbatim)
• expectation: What should trigger a notification

Step 2: Write Service Code

After creating the service, write the code to the returned servicePath.

Before writing code: Read reference/templates-minimal.md for the recommended pattern. For more complex scenarios, read the appropriate full template.

Pre-built invoke helper: The service_create tool automatically generates an invoke helper file in the service directory:

• Node.js: invoke.js — use const { invoke, dryRunResult, DRY_RUN, SERVICE_ID } = require('./invoke');
• Python: invoke.py — use from invoke import invoke, dry_run_result, DRY_RUN, SERVICE_ID

Invoke API uses named parameters (NOT positional args):

• Node.js: await invoke({ context: CONTEXT, summary: '...', details: '...', metadata: {} })
• Python: invoke(context=CONTEXT, summary='...', details='...', metadata={})

This eliminates the need to copy-paste the invoke boilerplate. Just import and use it.

CRITICAL: Service Code Requirements

1. Service lifecycle depends on type:

• longRunning: Never exit - keep running indefinitely with setInterval
• scheduled: Exit with process.exit(0) after task completion (e.g., reminder sent, N executions done)

1. Use the pre-built invoke helper - Import from ./invoke instead of writing your own HTTP client
2. Implement local filtering first - Use algorithms/rules to filter data before calling API
3. Set appropriate thresholds - Use slightly lower thresholds than user specified to catch edge cases
4. Only call invoke when conditions are potentially met - Save LLM tokens for important decisions
5. Include context - Pass the user's original request and expectations to LLM
6. Validate external API responses - Always check HTTP status code AND response structure before accessing nested properties. External APIs may return rate limit errors, unexpected JSON, or HTML error pages.
7. Handle errors gracefully - Wrap all API calls in try-catch and log meaningful error messages. Don't let the service crash due to temporary API failures.
8. Respect rate limits - Free APIs often have rate limits (e.g., 10-30 requests/minute). Don't poll too frequently.
9. Implement dry run mode - The service MUST support dry run mode. Read reference/dry-run.md for the specification and patterns.
10. Only use built-in modules - Only use Node.js or Python standard library modules (http, https, fs, os, json, urllib, etc.). Do NOT use third-party packages (no axios, requests, cheerio, etc.) to avoid dependency issues.

IMPORTANT: Use setInterval() (Node.js) or loops (Python) to keep the service running. For scheduled type, call process.exit(0) when the task is complete.

Step 3: Verify with Dry Run (MANDATORY)

After writing the service code, you MUST run service_dry_run to verify it works. Read reference/dry-run.md for full verification criteria, iteration rules, and failure handling.

Step 4: Start the Service

Only after a successful dry run, use service_start with the serviceId to start the service.

Modifying Existing Services

When modifying a service, read reference/modification.md first — it describes the critical synchronization rules between code, CONTEXT, and service.json.

Available Tools

• service_create - Create a new service
• service_dry_run - Run a service in dry-run mode to verify it works (MANDATORY before starting)
• service_list - List all services and their status
• service_start - Start a service (only after successful dry run)
• service_stop - Stop a service
• service_delete - Delete a service
• service_get_info - Get detailed service information