Open AI settings
Click AI › AI settings…. (AI › Open AI assistant, Ctrl+Shift+L, opens the chat once a provider is set.)
SumiCAD can work with an AI in two ways: its own AI assistant (you bring an API key from Anthropic, DeepSeek, OpenAI, Google, OpenRouter, Moonshot or a free local model), or an AI app on your PC such as Claude Desktop or Claude Code, connected through MCP. Both use the same tools as you: every change is one undo step. Below: the setup, then what an AI can do, from easy to hard — only what really works today.
Click AI › AI settings…. (AI › Open AI assistant, Ctrl+Shift+L, opens the chat once a provider is set.)
Open the Provider list and pick one — Anthropic, DeepSeek, OpenAI, Google Gemini, OpenRouter, Moonshot, a local model or a custom server (table below). Each provider remembers its own address, model and key, so you can switch back and forth. Below: What the AI may read (the selection, the current story or the whole project) and Ask me before the AI changes the project (on by default: each change waits for your Apply).
Make an account at the provider, create an API key and add some credit (most are prepaid). Paste the key into API key and click Save key: it goes into the Windows keychain (Credential Manager) — never into a project, a settings file or a log — and is sent only to that provider. Test connection answers like Connected to api.deepseek.com · deepseek-flash · 850 ms; if it adds but this model cannot use tools, pick another model. Click Save, open the assistant and ask, for example, “Check the structure and tell me what to fix.”
AI › Connect an AI app (MCP)… › pick Claude Desktop, Claude Code or Other MCP apps › Copy configuration and paste it where the dialog says (Claude Desktop: Settings › Developer › Edit Config), then restart the AI app. Test connection checks the link. While SumiCAD is open, the AI works on the open project and each change is one undo step; AI apps that can read PDFs and folders can do the level-5 examples below.
Pick one in AI › AI settings… › Provider; the address and the model fill in by themselves. Checked 2026-10-19; you can type any other model the provider offers.
Address https://api.anthropic.com, model claude-sonnet-5-5. Key: platform.claude.com › Settings › API keys.
Address https://api.deepseek.com, model deepseek-flash. Key: platform.deepseek.com › API keys. A working session costs a few yen.
Address https://api.openai.com/v1, model gpt-6.1-sol. Key: platform.openai.com › API keys.
Address https://generativelanguage.googleapis.com/v1beta/openai, model gemini-3.8-flash. Key: aistudio.google.com › Get API key.
Address https://openrouter.ai/api/v1, model ~openai/gpt-sol-latest. Key: openrouter.ai › Settings › Keys.
Address https://api.moonshot.ai/v1, model kimi-k3. Key: platform.kimi.ai › Console › API keys.
Address http://127.0.0.1:11434/v1 (LM Studio: :1234/v1), the model you installed, no key. Needs a strong PC, and the model must be able to use tools.
Your server's address, the model id, the API format and the Key header (Authorization: Bearer, x-api-key, api-key or none). Extra headers one Name: value per line — never put the key there.
AI › Connect an AI app (MCP)… › Copy configuration, then paste it into the AI app's settings (Claude Desktop: claude_desktop_config.json) or run the copied command once for Claude Code. While SumiCAD is open the AI edits the open project live and you watch every change; with SumiCAD closed it works on .sumi files. AI apps that run in a web browser cannot reach it.
Keep the key private: the connection is protected by a secret key. Never paste it into a chat, a screenshot or a web page; if it leaks, click New secret key.
Each example below was run on the built-in sample house with SumiCAD 0.6 (dev build 5, 2026-10-20) through the same tools the assistant uses. Type the sentence in the assistant (or in your AI app) in English or Japanese. Every change is one undo step: Ctrl+Z takes it back. SumiCAD and the AI prepare the work — a licensed 建築士 checks structure and permit documents.
“How many m² of siding are on this house?”
The AI reads the bill of quantities and answers per wall type. On the sample: 141.9 m² of EXT-01 larch siding and 98.4 m² of EXT-02 galvalume, plus 41 m of base flashing. Ask the same way for room areas, window counts, the 壁量 ratio or the estimate total.
“Change all posts to 105×105.”
The AI switches the frame system to 105: posts, 土台, beam widths and braces follow, including the one post the sample had at 120×120 — about a hundred members in one undo step. The structure check runs again by itself.
“Replace all 2F sliding windows with YKK AP APW 430.”
The AI finds the 2F sliding windows, searches the catalogue for the same size in the series you named, and applies the product: maker, code, size, U-value and frame colours update, the position stays. Tested on the sample with two 1,690 × 2,030 引違い窓 (LIXIL サーモスII-H → YKK AP APW 430 16520).
“On the 2F, make the east end overhang the 1F by 910 mm.”
The AI moves the 2F east wall out by 910 mm and stretches the north and south walls, the 2F floor and the roof with it. Then the check tells what the change means for the structure — posts of the overhang that stand on nothing, a floor beam that is now too weak — each with its fix, and the AI asks before applying them. Tested on the sample.
“Without adding posts on the X2 line, rearrange so the structure check passes.”
The AI runs the structure checks and uses the fixes that respect your condition: bracing panels or braces, belt beams 胴つなぎ, stronger wood, rigid floors. Tested: with the bracing taken off five 1F walls (壁量 Y 0.10, NG) it added 構造用合板 in 16 bays — no posts — and every check passed. In harder cases (a large cantilever) some rows may stay NG; the AI then lists the options (a 105×210 post, glulam, a bigger post) and asks you. It never makes posts bigger without asking.
“Here is the 1F plan PDF from the other builder. Rebuild it in SumiCAD.”
With an AI app that reads PDFs (Claude Desktop, Claude Code) connected through MCP: the AI reads the grid, dimensions, room names and window sizes, then lays out the floor — walls, rooms, doors, windows and the floor slab — in one step, and fixes what the check reports. Tested with a 1F plan sheet: 8 rooms, 8 doors and 8 windows, room areas equal to the PDF to 0.01 m². Check the result against the drawing; handwritten or scanned plans are harder.
“Set up a new project from the files in this folder: address, lot, survey points, ground survey.”
With an AI app that can read your files (Claude Code, Claude Desktop with file access): the AI makes the project, sets the stories and the grid, the address (the region for snow, wind, energy and the permit follows from it), lot number, land area and GPS position, draws the site boundary, puts the survey heights on the terrain and reads the SWS ground survey table. Tested with a folder of text and CSV files.
The built-in AI assistant cannot read attached files or pictures yet. Until then use an AI app connected through MCP for the two examples above.
You pay the provider per token (about ¾ of an English word or one Japanese character). The assistant sends a summary of the project with each request, so one question that changes the model uses some 20,000–100,000 tokens: from a few yen (DeepSeek) to a few hundred yen (the largest models) per working session. Local models cost nothing. Prices change often — check the provider's page.
The assistant says what happened: the key was refused (save it again), no credit left (top up), the model name is unknown (check it in AI settings), too many requests (it waits and tries again), the model cannot use tools (pick another), or the saved key belongs to another server address (save it again).
Back to your first project, or read the user guide.
More tutorials are on the way. Have a question now? Ask the AI assistant inside SumiCAD: it can explain any tool and guide you step by step — connect an AI.