Value the book

Valuing the book is a reporting plugin's: it reads the book of record's positions and the lake's prices, multiplies each trade-date quantity by its price, and shows the result. It records nothing: a valuation is computed and shown, never kept in core or published back.

The sample reporting plugin, from plugin-sample-reporting, does this: a reference implementation of valuing a book at a business date's prices, not a firm's valuation policy. You can run it as it is, or read it and build your own from the template below.

How to set up any reporting plugin, its common Datasets page and figures, and each person's own views, is Using a reporting plugin.

What the sample reporting plugin shows

Three pages, under Open and View, each fitting one screen, its rows paged, the third the Board:

• Consolidated: every account you may read, valued at the prices of the date you choose (the weekday before today unless you choose another), in the reporting currency. The total, how many positions it values and how many it leaves out; one row per instrument, with its total quantity, how many accounts hold it, its price and the dataset and kind it came from, and its value. A row opened shows each account's part.
• By account: one account at a time, chosen from those you may read, in its own base currency (the reporting currency where the account has none): each position's quantity, price and value, the total, and what it leaves out.

Each price names its dataset, kind and date and, where the page's prices stood at different times of day in different places (a crypto close at midnight UTC beside a New York close at 16:00), its time. A converted value names its rate. The page keeps itself current: when a source records a price it was waiting for, or restates one, the rows move, and a restated price says its version.

How it values a position

Each position is its trade-date quantity at the end of the date, times the date's price from the deployment's default sources, in the order the deployment admin sets:

What it is	Priced at
Cash	1, in its own currency
A money market fund whose record says its NAV is stable	1.00, by the plugin's named rule, labelled so, never as a source's price
A fund	its NAV for the date, else its close (an ETF)
Anything else	its close for the date, else its daily bar's close
A stablecoin, or a price quoted in one	through a source's price of that stablecoin, never assumed to be 1

A price the lake does not hold yet is asked of the source that serves it, and the page fills in when the source answers. A value in another currency is converted through the lake's rates, such as the Federal Reserve's H.10: multiplied, divided where the rate is quoted the other way, or crossed through dollars, each rate up to a week older than the date, its date shown.

A position with no price or no rate is shown unvalued, with its reason, never as zero, and counted in what the total leaves out:

It says	What to do
asked of its source, not answered yet	Nothing: the page fills in when the source answers
no dataset covers it	Entitle a source that does (a fund's NAV needs a source carrying NAVs), or accept that it is valued elsewhere
its source is silent	Its admin looks at the source's Connection page
this plugin is not entitled to the dataset that covers it	A deployment admin entitles the plugin on the Data sources page
no rate into the currency it is shown in	Entitle a source of exchange rates, or choose a later date
its currency's cash instrument is not known here	The deployment holds no record of that currency: complete one on the Instruments page, or show it in another.
the deployment holds no record of it	The deployment admin looks at the Instruments page
a local line: the deployment's own record, never priced	Nothing to do here: the position is under a provisional local record, which is never priced, even where the lake holds a price. It is valued once the record resolves to the platform's, which needs an identifier the platform can match, such as a FIGI. See Review provisional records

Set it up

1. Data sources. Launch at least one data plugin and entitle this plugin to its datasets, setting the source priority where two datasets price the same thing: see Using a data plugin and License and entitle a dataset. Nothing is priced without one.
2. A book. Accounts with opening balances, recorded through an operations plugin, each account's base currency set on the dashboard's Accounts page.

3. Upload and launch it, from its repository, and approve its role, reporting:

   meridian plugin upload --dir plugin-sample-reporting
   meridian plugin launch sample-reporting <version> --instance sample-reporting-1
   

4. Its setting, on Manage, Settings, by an admin of the plugin: Reporting currency (reporting_currency), the ISO 4217 code Consolidated shows every account in, USD unless set. By account always shows an account in its own base currency. The plugin resolves the code to the deployment's cash instrument itself, as it does each account's base currency and a stable-NAV fund's currency, so any currency works, held in the book or not. A value that is not an ISO 4217 code is not used: Consolidated shows USD, and the plugin is unhealthy on Manage until the setting is corrected. Watchlist (watchlist) too: the instruments the Board shows.

5. Read on the plugin, granted by a deployment admin to the people who will look at valuations. Each person sees only the accounts they may read.

Through an agent

Each page is also a read tool on the deployment's MCP surface, answering exactly what the page shows the same person: read_valuation for Consolidated, read_account_valuation for By account, and read_board for the Board. An agent you have delegated to reads valuations as you would, and only the accounts you may read. A tool's answer includes the prices the page shows; an agent client may pass what it reads to its model's host, and whether a source's terms allow that is for the deployment's admin and its users to settle with each source.

It records nothing: a valuation is worked out each time it is looked at, and nothing it reads leaves the deployment.

Build your own

A reporting plugin of your own uses what the sample does. You need CLI 0.1.45 and SDK 0.28.0 (contract 24):

• The reads. A reporting plugin reads positions with list_positions and prices with list_prices, by business date, as of a recorded time, from the deployment's default sources, named datasets or side by side, and hears new prices for the subjects it names with receive(prices_recorded=..., subjects=...). See The lake in the Python SDK. A reporting plugin reads prices and bars, never trades or quotes.

• Its currency, by its code. A reporting plugin names its reporting currency by its ISO 4217 code and has core resolve it, read-only, with resolve_identifier:

  found = await plugin.resolve_identifier(
      identifiers=[meridian.Identifier(scheme="iso4217", value="EUR")], as_of_ns=day_ns)
  euro = found.instrument_id if found.found else ""
  

The reporting suite's resolves-its-reporting-currency case holds a plugin to it. Core holds a reporting plugin's resolve read-only, and a currency the deployment does not hold is fetched from the platform's master: see Instruments. - A template. meridian plugin new my-report --role reporting writes a reporting plugin that shows the positions in its account scope at the last close from the lake: each position, its close, the dataset it came from, the value it makes and the change over the week, on a Closes page under Open and View, which is also a read tool, read_report, for an agent the person delegated to. It resolves its reporting currency by its ISO 4217 code. Its tests run the reporting suite the SDK carries; meridian plugin check --verified does not hold that suite, only the custody, data and connectivity suites, so keep the test. The template is built on the role's common part, meridian.roles.reporting: a Datasets page under Manage (read_datasets), the figures "Last valued" and "Not priced", and the Reporting currency setting; role-pages holds it under --verified. See plugin new. - Each person's own views. Declare a setting per_person=True, save a person's values for them with plugin.set_own_settings(...) from a page under Open, and read them from each of their requests as request.own_settings. See The Python SDK. - Entitlements. A deployment admin entitles the plugin to the datasets it reads: see License and entitle a dataset.

A plugin reading a price it is not entitled to is answered without it, the dataset and field named, never with a zero.