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fragment-dev/fragment

v0.1.10MIT

Build money flows in your app (prepaid credits, wallets, payouts, escrow, spending limits) on a Fragment ledger whose rules the ledger itself enforces, and prove them with an independent judge.

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Fragment plugin for coding agents

Build the money parts of an app — prepaid credits, wallets, top-ups, marketplace payouts and fee splits, escrow, refunds, spending limits for agents or teams — on a Fragment ledger whose rules the ledger itself enforces. A wallet that would go negative, a payout that would settle twice or a capture larger than its hold is refused by Fragment, even if the app's code is wrong.

What's inside

PartWhat it does
money-flows skillThe entry point: when to use a ledger, building it into your app, proving it, and six recipes
money-flow-spec skillWrites the flow's spec: parties, states, amounts, rounding, time, failure, invariants, every field
ledger-rules skillDesigns a schema whose entry types enforce the invariants, from tested primitives
judge-a-flow skillProves the flow with an independent judge that also attacks the ledger directly
skills/money-flows/kit/The kit (Python 3.10+, standard library): primitives, a crash-safe service scaffold, a judge harness, a local ledger for tests
RecipesSpecs for prepaid credits, platform payouts, creator memberships, spending authority, escrow and lending, each built with the kit and judged
Fragment MCPOptional: your workspace's Fragment MCP server, for designing schemas and simulating flows

Setup

  1. Install: claude plugin marketplace add <this repo>, then claude plugin install fragment@fragment-plugins.
  2. Optional MCP: in the Fragment dashboard, open Workspace Settings > MCP > Add, copy the raw URL, and set it with /plugin configure fragment (option fragment_mcp_url). Then run /mcp to sign in.
  3. For ledgers from code: npm install -g @fragment-dev/cli and fragment login --browser.

Then ask for what you need, for example "add prepaid credits to this app".

What this plugin sends where

  • The skills and the kit run locally. The kit's local ledger stores data in a SQLite file you choose.
  • The local Fragment endpoint (local_server.py) listens on 127.0.0.1 only, keeps its ledgers in a folder on your machine (.fragment-local/ by default), and sends nothing anywhere.
  • With the MCP configured, Claude calls your workspace's Fragment MCP server with your authorization, to read and change schemas and scenarios in that workspace.
  • The kit's FragmentLedger calls the Fragment API with the Fragment CLI's stored credentials, to post entries and read balances on ledgers you name.
  • Nothing is sent anywhere else. The plugin never moves money: it records and checks balances. Payments run on your own rails (for example Stripe or a bank), under your control.

Safety

Work in a test workspace first. Never start a real payment without explicit confirmation of the amount and recipient.