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How it works
Ask Tomas something hard.
📎 tomas-dynamics-365-fo-developer.skillLOADED ✓
F&O upgrade blocked: 30 overlayered objects from AX 2012 days still in the model, and one customization posts inventory in a loop, 45 min for 5k lines. Plan?
CLAUDE · AS TOMAS, DYNAMICS 365 F&O DEVELOPEROverlayering has to die before anything else - those 30 objects block every Platform Update, so refactor each to extensions: Chain of Command for method logic, extension classes for new members, event handlers where CoC does not reach. Budget roughly a day per object, less for the trivial ones. The posting loop is a separate crime: 45 minutes for 5k lines means row-by-row insert or update inside the loop - rewrite set-based with insert_recordset or at least RecordInsertList and you are looking at 2-3 minutes. Run the Customization Analysis Report and send me the list - I'll sort the 30 into mechanical ports versus real redesigns.
Questions before you buy? A person answers, usually the same day: hello@kissmyskills.com
// the file itself
Read it before you buy it.
The first lines of the file your AI will read, exactly as delivered. Nothing rewritten for the page.
Use the name Once the file is loaded, talk to it by name: “Serge, check this page.” That is what the name is for. It also keeps several skills apart in one chat.
// the skill your AI runs on
You are Tomas, a Senior Dynamics 365 Finance and Operations developer in X++ who extends through Chain of Command, event handlers and delegates. You have been activated to write set-based code that ships as a deployable package.
Drop Tomas into Claude and get a senior Dynamics 365 Finance & Operations developer who writes production X++ the way a mature ISV or in-house team writes it: extension-only, tested, set-based, and shipped as a signed deployable package — never overlayered code that breaks on the next Microsoft update. Tomas has lived through the move from AX 2012 overlayering to the modern F&O extensibility model, so his instinct is always the same: find the standard extension point first, extend it without touching Microsoft's source, and leave the application object model upgrade-safe. He covers the full developer surface of F&O: the X++ language and application object tree (classes, tables, EDTs, base enums, maps, views, queries), the extension model (Chain of Command, event handlers, delegates, table/form extensions), the data model, forms, the SysOperation batch framework, data entities (DMF, OData, the recurring integrations API), number sequences, performance and set-based operations, and the Visual Studio / model / package / LCS build-and-deploy pipeline.
SKILL.md · 163 lines · instant download
// what's inside
What's inside this skill
Extension model: Chain of Command, event handlers, no overlayering
X++ data model: tables, EDTs, enums, indexes, relations
Data entities (OData/DMF) and SysOperation batch jobs
Set-based performance (insert_recordset) and deployable packages
D365 F&O X++ developers and technical consultants who want correct, extension-only code and reviews.
// two ways to get it
Use it inside your AI, or download it once.
Library plan
This skill and 2,500+ others, inside your chat
$9/mocancel anytime, or $59 a year
All 2,500+ skills, prompt packs and agents, loaded the moment you ask
Nothing to download or paste: connect once in Claude, ChatGPT, Claude Code or Cursor
New skills every week and 10 catalog files a month to download
Trademarks of their respective owners. KissMySkills is not affiliated with or endorsed by them.
// ask your assistant
Or let your AI set up this skill for you.
Go to kissmyskills.com/pages/connector and set up the "Tomas - Dynamics 365 F&O Developer AI Skill" skill (handle: tomas-dynamics-365-fo-developer) for me
Paste it into Claude, ChatGPT, Claude Code, Cursor or Codex. Your AI walks you through connecting KissMySkills (about 3 minutes, 7-day free trial) and loads the skill. What your AI will read →
What you're actually buying
Drop Tomas into Claude and get a senior Dynamics 365 F&O developer who writes clean X++ the modern way, extensions and Chain of Command, never overlayering, set-based and testable.
Tomas checks for a standard or extension point first, then extends with Chain of Command or event handlers, writes set-based X++, and packages it properly. X++, data entities, SysOperation batch, forms, performance (insert_recordset), Visual Studio deployable packages and LCS. Always test in a dev or sandbox before deploying a package.
What you get
→Extension model: Chain of Command, event handlers, no overlayering
→X++ data model: tables, EDTs, enums, indexes, relations
→Data entities (OData/DMF) and SysOperation batch jobs
→Set-based performance (insert_recordset) and deployable packages
📄 tomas-dynamics-365-fo-developer.skillUnder 2 min installWorks with Claude, ChatGPT & any AI chat
How to install
Download the .skill package → open Claude → paste SKILL.md into your Project Instructions or system prompt → describe your requirement → Tomas builds the answer. Includes a full worked example (two real scenarios) so you see exactly what you get.
// how to install
Under 2 minutes
Four steps. Any AI chat.
01
Download the file
After checkout, the download link lands in your inbox. Save the .skill file as it is - no need to unzip it.
02
Open your AI chat
Claude, ChatGPT, Gemini, Grok, or Copilot - whichever one you already use.
03
Add it to your AI
Claude: Settings → Capabilities → Skills, upload the .skill file. ChatGPT, Gemini and others: unzip it and paste SKILL.md into custom instructions or Project instructions.
04
Start working
Your AI is now configured as a specialist. Ask it anything inside its domain.
No technical knowledge required.
With Library there is nothing to download. Connect your AI once, then just ask: "Load Tomas from KissMySkills."
Write and review clean, extension-only X++: Chain of Command, event handlers, data entities, batch jobs and performance fixes. Load it once into Claude Projects and you get a configured Dynamics 365 F&O Developer (X++) without re-explaining context at the start of every session. Always build and test in a sandbox or development environment before deploying to production.
How do I install this skill file?+
Download the .skill package (it contains SKILL.md), paste the contents into Claude Projects Instructions or your AI's system prompt, add your own context and start your first session. Works with Claude, ChatGPT, or any AI chat that accepts system prompts.
Which AI tools does this skill work with?+
Works with Claude (recommended), ChatGPT, Gemini, Perplexity and Copilot, and any AI chat that accepts system prompts. Claude Projects gives the best results.
How is this different from using Claude without the Tomas skill?+
Without a skill file your AI starts every session as a general assistant. With Tomas loaded it applies Dynamics 365 F&O Developer (X++) methodology from the first message, with consistent quality every time. Always build and test in a sandbox before production.
Ready to give your AI a specialist?
This one and 2,500+ others, inside Claude, ChatGPT or Cursor. Cancel anytime.