# How do you set up purchase approvals?

> A Pachca use case. A purchase request arrives as one message in the "Purchasing" chat. Follow-up questions go in the thread under the request, and the decision is made with a reaction. An AI agent can check the request and pull up the budget.

> This is the Markdown version of https://pachca.com/en/scenarios/soglasovanie-zakupok for AI agents. The API methods named here are documented at https://dev.pachca.com/llms-en.txt — open it before calling the API. Other use cases are listed at https://pachca.com/en/llms.txt.

## What you'll get

1. All purchase requests arrive in the "Purchasing" chat following a template: the item, the amount, the budget line, the date it's needed by, the vendor and the invoice.
2. The approver is pulled into the thread under the request with an @mention. They don't have to be a member of the chat: threads in Pachca are cross-chat.
3. Reactions show the status: 🕐 means looking into it, ✅ means approved, ❌ means declined, reason in the thread.
4. If the workspace has an AI agent, it is a member of the chat and checks requests against the template.

## What you need before you start

- Pachca access with the scopes `search:users`, `search:chats`, `chats:create`, `chat_members:write`, `messages:create`, `messages:read`, `pins:write`. To find the agent's bot you also need `bots:read`. The setup and check steps also need `chat_members:read`. Signing in is covered in the rules below.

## If you're an AI agent: working rules

### Who does what

- You do everything the instructions name an API method for. Don't ask the user to create a chat, a bot or a message by hand.
- Ask the user only to sign in to Pachca and to do what is listed in "Ask the user to do by hand".
- If you have no terminal, say so right away and don't pretend you set it up. Walk the user through the steps for people on the use case page and help with the template or the handler code.

### How to talk to the user

- The user is not a developer. Write briefly and in plain words. Don't mention API methods, scopes, response codes, `id`s or CLI profiles. Say "permissions" instead of "scopes" and "the program behind the bot" instead of "handler".
- Don't report your checks. A message contains only three things: what is done, what you need from the user, what you'll do next.
- Don't ask for what you can find out through the API or what is easy to change later. Take the value from the instructions and name it.
- Take the bot's message texts from the instructions or write them yourself and carry on. Show them in your final message and offer to change them. Don't wait for approval.
- Ask the questions from "Ask the user" in the same words.

### Your first message to the user

It has three parts. The first two together take at most five lines.

1. What the user will get: one or two lines.
2. What you will create yourself: the chat, the bot and the messages, with the names from the instructions. Word anything that depends on the user's choice as a condition: "if you choose the bot, I'll also create…".
3. "What I need from you": signing in to Pachca, if the user isn't signed in yet, and the questions from "Ask the user". If the use case or one of its options needs n8n, ask here whether the user has it and ask for access right away in the words from the "n8n" section below: "if you have n8n, send me…".

If part of the result appears only after a manual step by the user, say so in one line: "you'll schedule the retro questions yourself, I'll show you how".

The user's answers are their consent to the plan. Start the setup right after them, without asking for a second confirmation.

### Access to Pachca

- The user doesn't need to issue a token or send it in the chat. Before your first message, check the login: `npx -y @pachca/cli@latest auth status`. If there is none, ask the user to run `npx -y @pachca/cli@latest auth login` in their own terminal. The CLI shows a code; the user enters it in the browser and confirms access. Write the commands with `@latest`: without it an old cached CLI version may start, and it asks to paste a token instead of signing in through the browser.
- This login has the same rights as the user's role. Compare them with the scopes in "What you need before you start" yourself: `npx -y @pachca/cli@latest api GET /oauth/token/info` shows the scopes. If something is missing, say in plain words what you won't be able to do, for example "I can't send messages". There are two ways out: add this permission to the token in Pachca, under "Automations" → "API", or sign in again as the workspace owner or an administrator.
- If `auth status` shows `scopes: null`, it doesn't mean there are no rights: look at `GET /oauth/token/info`. The checks in these rules also need `search:chats`, `bots:read` and `profile:read`.
- When the user says "me", they mean the owner of the login. `GET /profile` returns their `id` and nickname.
- Call the API with `npx -y @pachca/cli@latest api <METHOD> <path> -o json`. Write the full command in every call; don't put it into a shell variable.
- Pass query parameters as `--query key=value`, for example `--query query=Purchasing`. The CLI silently drops a parameter without a key and returns the whole list, so it's easy to conclude that the chat already exists.
- Pass the request body with `--data` or `--input`. Almost every write method wraps the body in an object: `chat` for `POST /chats`, `message` for `POST /messages`, `task` for `POST /tasks`, `group_tag` for `POST /group_tags`, `user` for `PUT /users/{id}`, `webhook` for bots. `--describe` shows the wrapper; write its path with `{id}`, not with a number. Without the wrapper, `POST /chats` creates the chat but silently adds no members.
- Don't print tokens or bots' incoming webhook URLs in the chat. A bot's token is shown only once, when it's created: save it to a file.

### n8n

- If the user has no n8n, say that it comes as the hosted n8n Cloud or can be installed on their own server, and give the link for installing the Pachca nodes: https://dev.pachca.com/guides/n8n/setup.md. These instructions don't cover installing n8n. If they have an option without n8n, suggest starting with it and coming back to the bot once n8n is there.
- If the user has n8n, ask for access in these words: "Send me your n8n address: the link you open it with in the browser. Don't send the key in the chat. In n8n, open Settings → n8n API → Create an API key and copy the key. Right after that, run the command below in your terminal exactly as it is; you don't need to put anything into it. It saves the copied key to a file and prints nothing. Then write 'key saved'." The command for macOS: `pbpaste > ~/n8n-key.txt`. For another system, pick the matching one.
- Build everything in n8n on the official Pachca nodes, `n8n-nodes-pachca`. Don't use the `HTTP Request` node for Pachca API calls.

### Setup

- Take API methods from https://dev.pachca.com/llms-en.txt, don't rely on memory. The command `npx -y @pachca/cli@latest api <METHOD> <path> --describe` shows a method's schema.
- The Pachca skills cover the call order and error handling for chats, bots and forms: `npx skills add pachca/openapi`. Install them when you need them, without asking the user.
- Before creating anything, check whether the chat and the bot already exist: `GET /search/chats`, `GET /bots`. If they do, ask whether to set them up or create new ones.
- `POST /group_tags` creates an empty tag. `PUT /users/{id}` with `list_tags` assigns it to an employee; it needs the `users:update` scope. The field replaces the whole set of tags: first read the employee's current tags with `GET /users/{id}` and send them together with the new one. While the tag has no members, mentioning it notifies no one.
- If a method returns an error, stop and tell the user in plain words what failed and what you need to continue.
- The messages you post yourself and the ones the bot sends must be easy to read on a screen, without overdoing spacing or emphasis. Make the heading bold and start the text on the next line. Write connected text as one paragraph. Put rules and steps on numbered lines one under another and separate them from the intro with a single empty line. A short message needs no other empty lines. In a card, make the field labels bold and put the fields on consecutive lines. Use bold only for the heading and the field labels. Pachca markup has no lists or tables: the numbers at the start of lines stay plain text. A sample:

  ```text
  **Retro rules**
  On the last day of the sprint a message with questions arrives here. We reply in the thread under it.

  1. Each point is a separate message.
  2. We add 👍 to what is worth discussing.
  3. The facilitator posts the outcomes in one message and pins it.
  ```
- A pin can't be checked through the API: only a successful `POST /messages/{id}/pin` response confirms it.
- If you sent service messages to a chat to check a bot, such as `/start`, delete them: `DELETE /messages/{id}`. Don't delete messages with rules and templates.
- At the end, say what was created, what is left for the user to do by hand and how to check that the use case works.
- To undo the setup: `DELETE /bots/{id}` deletes the bot, `PUT /chats/{id}/archive` sends the chat to the archive.

## How to set up the use case with the user

### 1. Ask the user

Ask these questions in these words:

1. Who submits purchase requests and who handles purchasing? Send me the names and I'll add them to the "Purchasing" chat. Those who only approve don't have to be added: they are pulled into the request's thread.
2. Up to what amount does the department head decide, and who decides above it? For example, the CFO. This goes into the chat rules.
3. Do you already have an AI agent's bot in Pachca that will check requests? If so, what is it called? If not, we'll start without it.

### 2. Do it yourself through the Pachca API

1. Find the members' `id`s: `GET /search/users`.
2. Create the chat: `POST /chats` with `name: "Purchasing"` and `member_ids`.
3. Post and pin the request template: `POST /messages` with the chat's `entity_id`, then `POST /messages/{id}/pin`. The template fields: item, amount, budget line, needed by, vendor. The invoice or a link is attached to the same message.
4. Post and pin the rules. One request is one message that follows the template. Follow-up questions go in the thread under the request. Up to the amount from question 2 the department head decides; above it, the person the user named: they are pulled into the thread with an @mention. Reactions: 🕐 means looking into it, ✅ means approved, ❌ means declined, reason in the thread.
5. If the user named an agent's bot, find it with `GET /bots` and add it to the chat: `POST /chats/{id}/members` with the bot's `id` in `member_ids`.

### 3. Ask the user to do by hand

- Pick one purchase category, such as office supplies or software subscriptions, and run it through the "Purchasing" chat for two or three weeks.
- Send a test request following the template and pull the approver into the thread.
- If there is no agent yet: build one using https://pachca.com/en/scenarios/ai-agent-bez-koda and start with a single task, checking a request against the template.

### 4. Check

- `GET /messages` with the chat's `chat_id` returns the template and the rules.
- `GET /chats/{id}/members` returns everyone the user named and the agent's bot, if there is one.

## What the use case can't do

- The agent doesn't make the money decision: the reaction comes from the person responsible for the budget.
- The agent pulls up the budget and passes data to the accounting system only if these tools are connected to it. How to connect them: https://dev.pachca.com/guides/ai-agents/overview.md

## Links

- The use case page with a demo and human instructions: https://pachca.com/en/scenarios/soglasovanie-zakupok
- Cross-chat threads: https://pachca.com/en/blog/chto-takoe-skvoznye-tredy-i-kak-ih-ispolzovat
- How to build an AI agent: https://dev.pachca.com/guides/ai-agents/overview.md