Expensify

Build me a focused expense management workflow for the personal core of Expensify. Requirements:

- Use exactly this stack: Next.js 15 + TypeScript + SQLite. Model accounts, source transactions, ledger entries, reconciliations, and reports; keep stable source IDs and timestamps.
- Paid product context: Receipt capture, cards, reimbursements, travel, invoices, and accounting sync. Build only this DIY scope: Build a private expense management ledger that imports user-supplied CSV files, categorizes entries, reconciles balances, and exports reports.
- For expense management, import one user-owned statement or enter a transaction with currency and source identifier.
- Store money as integer minor units, reject duplicate source IDs, and record corrections as new audit events.
- Reconcile a statement period and export a report with the unmatched entries visible.
- Use a local web page with input, progress, review, and export views. Required input or access: CSV exports from the user's own accounts.
- Acceptance: with one labelled sample, show the input, saved intermediate state, and exported result; verify this invariant: The sum of debits and credits must balance for posted entries; an import retry cannot change the closing balance.
- Out of scope: tax and accounting rule updates; audited security and recovery. Keep this a personal, inspectable workflow.
- Include a README with setup, a sample input, required keys or permissions, data location, and the supported scope.

# AGENTS.md — Build guide for Expensify

## Project scope
Build a private expense management ledger that imports user-supplied CSV files, categorizes entries, reconciles balances, and exports reports.

Catalogue verdict: no. Do not mistake the interface for the product. Expensify's durable value is banking, compliance, trust, which a solo one-shot build cannot reproduce responsibly. The prompt therefore builds only the closest honest personal consolation tool.
Use the implementation prompt below to define the deliverable. Complete each phase's acceptance checks before extending the scope.

## Working agreement
- Inspect the repository and its existing instructions before choosing paths, dependencies or commands. Keep one coherent stack and explain changes to the proposed architecture.
- Plan a vertical slice that accepts a real input and produces the useful output described below. Persist only the state the prompt calls for; respect memory-only and upstream-managed workflows. Use fixtures only when they are clearly labelled.
- After scaffolding, document the actual install, development, check and build commands in README and keep them synchronized with the package or project manifest. Do not report commands as successful unless they ran.
- Work in small steps. At handoff, list implemented flows, checks actually performed, remaining blockers, and any credentials or provider setup the owner must supply.
- Do not publish, spend money, contact customers, delete source data or run irreversible migrations without the project owner's authorization.

## Prerequisites
- Node.js 22
- SQLite
- CSV exports from the user's own accounts
- Explicit README warning that this is a consolation build, not a production replacement

## Stack and architecture
- Use exactly this stack: Next.js 15 + TypeScript + SQLite.
- Model accounts, source transactions, ledger entries, reconciliations, and reports; keep stable source IDs and timestamps.
- Interface for this expense management workflow: a local web page with input, progress, review, and export views.

## Security and data integrity
- The sum of debits and credits must balance for posted entries; an import retry cannot change the closing balance.
- Validate imported records and file paths; keep user data within the storage location named in the prompt.
- State the practical limit: tax and accounting rule updates.

## Agent implementation rules
- Project rule, data: Model accounts, source transactions, ledger entries, reconciliations, and reports; keep stable source IDs and timestamps.
- Project rule, behavior: For expense management, import one user-owned statement or enter a transaction with currency and source identifier.
- Project rule, recovery: The sum of debits and credits must balance for posted entries; an import retry cannot change the closing balance.

## Optional agent skills and references
No installable skill is listed for this guide; use the project rules and the stack documentation.

Read the linked SKILL.md and its dependencies before adding a skill. Select only the skills matching this project's runtime and task; their documentation does not supply API access, credentials or approval to perform external actions. Pin the reviewed revision where the tool supports it. Follow the chosen agent's documented project-level installation mechanism.

## Distribution ideas
These are optional planning notes. Obtain the owner's approval before publishing or contacting anyone.
- Demonstrate this expense management operation with sample or user-owned data: For expense management, import one user-owned statement or enter a transaction with currency and source identifier.
- Show a concrete result or export: Reconcile a statement period and export a report with the unmatched entries visible.
- State the practical limit: tax and accounting rule updates.

## Engineering roadmap
1. Phase 1, architecture and data: Use exactly this stack: Next.js 15 + TypeScript + SQLite. Model accounts, source transactions, ledger entries, reconciliations, and reports; keep stable source IDs and timestamps.
2. Phase 2, implement: For expense management, import one user-owned statement or enter a transaction with currency and source identifier.
3. Phase 3, implement: Store money as integer minor units, reject duplicate source IDs, and record corrections as new audit events.
4. Phase 4, review and output: Reconcile a statement period and export a report with the unmatched entries visible.
5. Phase 5, recovery and acceptance: Verify this invariant with a saved fixture: The sum of debits and credits must balance for posted entries; an import retry cannot change the closing balance. State the practical limit: tax and accounting rule updates.

## Paid-product capabilities outside this build
- tax and accounting rule updates
- audited security and recovery
- multi-user controls and accountant workflows
- bank, payment, tax, and reconciliation integrations
- live bank feeds and payment rails

## Implementation prompt
Build me a focused expense management workflow for the personal core of Expensify. Requirements:

- Use exactly this stack: Next.js 15 + TypeScript + SQLite. Model accounts, source transactions, ledger entries, reconciliations, and reports; keep stable source IDs and timestamps.
- Paid product context: Receipt capture, cards, reimbursements, travel, invoices, and accounting sync. Build only this DIY scope: Build a private expense management ledger that imports user-supplied CSV files, categorizes entries, reconciles balances, and exports reports.
- For expense management, import one user-owned statement or enter a transaction with currency and source identifier.
- Store money as integer minor units, reject duplicate source IDs, and record corrections as new audit events.
- Reconcile a statement period and export a report with the unmatched entries visible.
- Use a local web page with input, progress, review, and export views. Required input or access: CSV exports from the user's own accounts.
- Acceptance: with one labelled sample, show the input, saved intermediate state, and exported result; verify this invariant: The sum of debits and credits must balance for posted entries; an import retry cannot change the closing balance.
- Out of scope: tax and accounting rule updates; audited security and recovery. Keep this a personal, inspectable workflow.
- Include a README with setup, a sample input, required keys or permissions, data location, and the supported scope.

## Completion evidence
Demonstrate the prompt's acceptance scenarios against the scoped workflow. Include setup from a clean checkout and failure recovery. Check persistence across restart and export/restore only for the state the prompt says to store; for memory-only tools, confirm that temporary content is discarded as specified. Record actual results and remaining limitations. A detailed plan alone does not establish a working replacement.