Tiller

Build me a focused budgeting, invoicing and small-business finance workflow for the personal core of Tiller. Requirements:

- Use Next.js 15, TypeScript, SQLite, Drizzle ORM, and local-first encryption. Model accounts, source transactions, categories, balances, and reports; keep stable source IDs and timestamps.
- Paid product context: Import financial CSV files into a transparent spreadsheet model with rules and templates. Build only this DIY scope: Import financial CSV transactions into a transparent spreadsheet model, categorize them with rules and templates, reconcile balances, and export clean reports without moving money.
- Support CSV and OFX import with saved column mappings and duplicate detection.
- Implement accounts, transactions, transfers, categories, payees, notes, and split transactions.
- Add deterministic categorization rules whose matches can be inspected and undone. Keep an immutable import log and require explicit confirmation before destructive changes.
- Use a local web page with input, progress, review, and export views. Required input or access: CSV or OFX exports from financial institutions; local encrypted storage. Keep credentials in .env.
- Recovery: If optional exchange-rate API key is unavailable, keep the source record and show a recoverable error instead of a fabricated result.
- Acceptance: with one labelled sample, show the input, saved intermediate state, and exported result; verify this invariant: An invalid input or interrupted operation must retain the source and show a recoverable state; exported records must reload with the same IDs.
- Out of scope: automated bank feeds, spreadsheet connectors, templates, and support; direct bank feeds. 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 Tiller

## Project scope
Import financial CSV transactions into a transparent spreadsheet model, categorize them with rules and templates, reconcile balances, and export clean reports without moving money.

Catalogue verdict: no. A consolation build is possible, but the paid product's decisive value sits outside a solo rebuild. For Tiller, import financial CSV files into a transparent spreadsheet model with rules and templates. The hard boundary is automated bank feeds, spreadsheet connectors, templates, and support, plus financial integrations, compliance, and trust.
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
- CSV or OFX exports from financial institutions
- local encrypted storage
- optional exchange-rate API key

## Stack and architecture
- Use Next.js 15, TypeScript, SQLite, Drizzle ORM, and local-first encryption.
- Model accounts, source transactions, categories, balances, and reports; keep stable source IDs and timestamps.
- Interface for this budgeting, invoicing and small-business finance workflow: a local web page with input, progress, review, and export views.

## Security and data integrity
- If optional exchange-rate API key is unavailable, keep the source record and show a recoverable error instead of a fabricated result.
- Keep API keys and OAuth secrets in .env; redact them from logs, generated files, and error responses.
- State the practical limit: automated bank feeds, spreadsheet connectors, templates, and support.

## Agent implementation rules
- Project rule, data: Model accounts, source transactions, categories, balances, and reports; keep stable source IDs and timestamps.
- Project rule, behavior: Support CSV and OFX import with saved column mappings and duplicate detection.
- Project rule, recovery: If optional exchange-rate API key is unavailable, keep the source record and show a recoverable error instead of a fabricated result.

## 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 budgeting, invoicing and small-business finance operation with sample or user-owned data: Support CSV and OFX import with saved column mappings and duplicate detection.
- Show a concrete result or export: Provide reconciliation, monthly budget, cash-flow, net-worth, and export views.
- State the practical limit: automated bank feeds, spreadsheet connectors, templates, and support.

## Engineering roadmap
1. Phase 1, architecture and data: Use Next.js 15, TypeScript, SQLite, Drizzle ORM, and local-first encryption. Model accounts, source transactions, categories, balances, and reports; keep stable source IDs and timestamps.
2. Phase 2, implement: Support CSV and OFX import with saved column mappings and duplicate detection.
3. Phase 3, implement: Implement accounts, transactions, transfers, categories, payees, notes, and split transactions.
4. Phase 4, review and output: Add deterministic categorization rules whose matches can be inspected and undone. Provide reconciliation, monthly budget, cash-flow, net-worth, and export views.
5. Phase 5, recovery and acceptance: If optional exchange-rate API key is unavailable, keep the source record and show a recoverable error instead of a fabricated result. Verify this invariant with a saved fixture: An invalid input or interrupted operation must retain the source and show a recoverable state; exported records must reload with the same IDs. State the practical limit: automated bank feeds, spreadsheet connectors, templates, and support.

## Paid-product capabilities outside this build
- automated bank feeds, spreadsheet connectors, templates, and support
- direct bank feeds
- tax filing guarantees
- payroll and payments
- accountant ecosystem and support

## Implementation prompt
Build me a focused budgeting, invoicing and small-business finance workflow for the personal core of Tiller. Requirements:

- Use Next.js 15, TypeScript, SQLite, Drizzle ORM, and local-first encryption. Model accounts, source transactions, categories, balances, and reports; keep stable source IDs and timestamps.
- Paid product context: Import financial CSV files into a transparent spreadsheet model with rules and templates. Build only this DIY scope: Import financial CSV transactions into a transparent spreadsheet model, categorize them with rules and templates, reconcile balances, and export clean reports without moving money.
- Support CSV and OFX import with saved column mappings and duplicate detection.
- Implement accounts, transactions, transfers, categories, payees, notes, and split transactions.
- Add deterministic categorization rules whose matches can be inspected and undone. Keep an immutable import log and require explicit confirmation before destructive changes.
- Use a local web page with input, progress, review, and export views. Required input or access: CSV or OFX exports from financial institutions; local encrypted storage. Keep credentials in .env.
- Recovery: If optional exchange-rate API key is unavailable, keep the source record and show a recoverable error instead of a fabricated result.
- Acceptance: with one labelled sample, show the input, saved intermediate state, and exported result; verify this invariant: An invalid input or interrupted operation must retain the source and show a recoverable state; exported records must reload with the same IDs.
- Out of scope: automated bank feeds, spreadsheet connectors, templates, and support; direct bank feeds. 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.