invoice-generator

TL;DR

Generates professional, print-ready invoices as self-contained HTML files using the JM Labs dark brand identity. Accepts client details, line items, tax configuration, and payment terms. Produces bilingual (ES/EN) output with automatic subtotal/tax/total calculation, structured bank details placeholder, and CSS print stylesheet for pixel-perfect PDF export.

When to Activate

• User requests an invoice, factura, or billing document for a client engagement.
• User asks for a reusable invoice template with JM Labs branding.
• User provides line items, amounts, or service descriptions expecting a formatted financial document.
• User mentions "create invoice", "invoice template", "factura", or "generar factura".
• Do NOT activate for general pricing discussions, cost estimations, or budget planning (use cost-estimation or pricing-strategy instead).

Invoice Structure & Layout

Header Block

The invoice header contains:

• JM Labs logo placeholder ([LOGO] div with brand colors, replaceable with base64 image).
• Invoice number: auto-generated format JML-YYYY-NNN based on current date.
• Issue date and due date (calculated from payment terms).
• Issuer block: JM Labs legal name, NIT/tax ID placeholder, address, contact email.
• Client block: company name, contact person, tax ID, billing address, purchase order reference (optional).

Line Items Table

Each row contains:

Column	Type	Notes
#	Auto-increment	Row number
Description	Text	Service or product description, bilingual if requested
Quantity	Number	Decimal-safe (e.g., 1.5 hours)
Unit Price	Currency	Formatted with thousands separator
Subtotal	Calculated	qty x unit_price, auto-computed

Totals Block

• Subtotal: sum of all line item subtotals.
• Tax line(s): configurable tax name and rate (default: IVA 19% for Colombia).
• Discount line: optional, percentage or flat amount.
• Total: final amount in bold, large font.
• Currency indicator: ISO 4217 code (COP, USD, EUR) displayed next to amounts.

Payment Terms Section

• Payment deadline (Net 15, Net 30, Net 60, or custom).
• Accepted payment methods.
• Bank details placeholder with fields for: bank name, account type, account number, SWIFT/BIC, beneficiary name.
• Late payment policy note (optional).

Footer

• Legal disclaimer text (bilingual).
• Document generation timestamp.
• Page number for multi-page print.

Brand & Visual Design

The invoice follows the JM Labs dark brand system:

• Background: #0a0a0a (near-black) with #1a1a2e card surfaces.
• Primary accent: #e94560 (coral red) for headings, totals, and highlights.
• Text: #eaeaea (light gray) for body, #ffffff for totals.
• Font stack: 'Inter', 'Segoe UI', system-ui, sans-serif.
• Table styling: alternating row backgrounds (#1a1a2e / #16213e), no outer borders, subtle bottom borders on rows.
• Print override: @media print stylesheet flips to white background, dark text, hides non-essential elements, forces break-inside: avoid on tables.

Bilingual Support (ES/EN)

Every text element includes both languages:

• Labels are rendered as Factura / Invoice, Subtotal / Subtotal, Total / Total.
• The lang parameter controls primary language (displayed prominently) vs secondary (displayed in smaller text or parentheses).
• Date format adapts: DD/MM/YYYY for ES, MM/DD/YYYY for EN.
• Currency formatting adapts: $1.500.000 for COP, $1,500.00 for USD.

Trade-off Matrix

Decision	Option A	Option B	Default
Output format	Single HTML file	HTML + separate CSS	Single HTML (portable)
Tax calculation	Auto-compute in HTML	Static values only	Auto-compute (JS-free CSS calc display)
Logo embedding	Base64 inline	External URL reference	Base64 placeholder
Multi-page support	CSS page-break rules	Single continuous page	CSS page-break
Currency	Single currency	Multi-currency per line	Single currency
Number formatting	Locale-aware JS	Pre-formatted strings	Pre-formatted strings (no JS dependency)

Assumptions & Limits

• Assumption: invoices are for professional services, not physical goods with shipping. [INFERRED]
• Assumption: Colombian tax regime (IVA 19%) is the default; user can override. [EXPLICIT]
• Assumption: bank details are placeholders; user fills in sensitive data manually. [EXPLICIT]
• Limit: no PDF generation natively; user prints to PDF from browser.
• Limit: no recurring invoice scheduling; this produces one-off documents.
• Limit: no integration with accounting software; output is standalone HTML.
• Limit: line items capped at 50 rows for print layout stability.

Edge Cases

1. Zero-amount invoice: proforma or courtesy invoices with $0 total. Render normally with "PROFORMA" watermark and skip payment terms section.
2. Multi-tax jurisdiction: client requests both IVA and withholding tax (retefuente). Add multiple tax lines with separate rates and labels.
3. Extremely long descriptions: line item descriptions exceeding 200 characters. Truncate at 200 chars in table, add full description as footnote.
4. Currency mismatch: user provides amounts in USD but requests COP invoice. Flag the mismatch, ask for exchange rate or confirmation, never silently convert.
5. Missing client info: user provides incomplete client data. Generate invoice with [PENDING] placeholders for missing fields, add warning banner.

Good vs Bad Example

Good

Input: "Create an invoice for Acme Corp, 3 items: Discovery phase 40hrs at $150/hr,
        Architecture design 20hrs at $200/hr, Documentation 10hrs at $100/hr.
        Net 30, USD."

Output: Complete HTML invoice with:
- Invoice number JML-2026-001
- All 3 line items with calculated subtotals ($6000, $4000, $1000)
- Subtotal: $11,000.00
- Tax: configurable (0% for international, or IVA if Colombian)
- Total: $11,000.00
- Due date: 30 days from issue date
- Bank details placeholder section
- Print-ready CSS

Bad

Output that:
- Uses generic white template with no JM Labs branding
- Hardcodes tax rate without asking jurisdiction
- Embeds real bank account numbers in the template
- Requires external CSS file or CDN links (not self-contained)
- Outputs a markdown table instead of proper HTML
- Omits payment terms or due date calculation

Validation Gate

Before delivering the invoice, verify:

• Output is a single self-contained HTML file (no external dependencies).
• JM Labs dark brand colors applied: #0a0a0a, #e94560, #1a1a2e.
• All line item subtotals are mathematically correct (qty x unit_price).
• Grand total equals subtotal + tax - discount (verified manually).
• @media print stylesheet included with light-background override.
• Bilingual labels present for all section headers and field names.
• Bank details section contains ONLY placeholders, never real account data.
• Invoice number follows JML-YYYY-NNN format.
• Due date correctly calculated from issue date + payment terms.
• Currency symbol and formatting consistent throughout document.
• No JavaScript dependencies; all calculations pre-rendered in HTML.
• File size under 50KB for email attachment compatibility.

Reference Files

File	Purpose
references/brand-tokens.md	JM Labs color palette, typography, spacing system
references/tax-config.md	Tax rates by jurisdiction (CO, US, EU defaults)
references/invoice-templates.md	HTML skeleton and CSS patterns for invoice layout
references/payment-terms.md	Standard payment term definitions and legal text