Add payments with TDS, invoice detail view and filterable History (Phase E2)

- Migration M8 adds payments (cash, TDS, mode, reference). Payment status is derived, never stored: unpaid, partially paid, paid, or overdue. Overpayment is rejected, TDS counts toward settling, and only issued invoices accept payments. list_invoices and get_invoice carry the paid, TDS and balance summary.
- New invoice detail view: archived-PDF preview, payments list, Record payment modal, Export, Duplicate (as a draft), Re-render and Cancel. An invoice with payments cannot be cancelled until they are deleted.
- History gets search, status, financial-year, month and client filters, sortable columns, pagination, footer totals and an FY summary. Cancelled invoices are excluded from totals. The per-row archive-status calls are gone; archiving is on the detail page.
- Rust tests for payments and the list summary; vitest for fiscal-year, money, filter and duplicate helpers.

PDF output and fingerprint goldens are unchanged. The new UI has not been run in a webview yet.

src-tauri/src/commands/invoice.rs

@@ -3,8 +3,9 @@ use super::series::{validate_series_format, MAX_NUMBER_LEN};
 use super::settings::{map_bank, map_settings, SETTINGS_COLS};
 use crate::db::format_number;
 use crate::gst::{self, TaxType};
+use super::payments::{derive_summary, summary_for, today_ist};
 use crate::models::{
-    BankAccount, DraftSummary, Invoice, InvoiceInput, InvoiceItem, InvoiceSummary, Settings,
+    BankAccount, DraftSummary, Invoice, InvoiceInput, InvoiceItem, InvoiceSummary, PaymentSummary, Settings,
 };
 use crate::AppState;
 use chrono::NaiveDate;
@@ -59,6 +60,8 @@ fn map_invoice(row: &Row) -> rusqlite::Result<Invoice> {
         archived_fingerprint: row.get(35)?,
         archived_at: row.get(36)?,
         items: Vec::new(),
+        payment: PaymentSummary::default(),
+        total_paise: 0,
     })
 }
 
@@ -90,6 +93,8 @@ fn fetch_invoice(conn: &Connection, id: i64) -> rusqlite::Result<Invoice> {
         map_invoice,
     )?;
     invoice.items = fetch_items(conn, id)?;
+    invoice.total_paise = gst::rupees_to_paise(invoice.total);
+    invoice.payment = summary_for(conn, id, &invoice.status, invoice.total, &invoice.due_date)?;
     Ok(invoice)
 }
 
@@ -460,6 +465,12 @@ pub fn issue_invoice(
 
 /// Issued invoices are never deleted: cancelling keeps the row and its number.
 pub fn cancel_invoice_impl(conn: &mut Connection, id: i64, reason: &str) -> Result<Invoice, String> {
+    let payments: i64 = conn
+        .query_row("SELECT COUNT(*) FROM payments WHERE invoice_id = ?1", params![id], |r| r.get(0))
+        .map_err(|e| e.to_string())?;
+    if payments > 0 {
+        return Err("This invoice has payments recorded. Delete them before cancelling it.".into());
+    }
     let now = chrono::Utc::now().to_rfc3339();
     let changed = conn
         .execute(
@@ -491,23 +502,42 @@ pub fn cancel_invoice(state: State<AppState>, id: i64, reason: String) -> Result
 #[tauri::command]
 pub fn list_invoices(state: State<AppState>) -> Result<Vec<InvoiceSummary>, String> {
     let conn = state.db.lock().map_err(|e| e.to_string())?;
+    list_invoices_impl(&conn)
+}
+
+/// One query: invoices left-joined to their payment sums. Status derivation happens in Rust
+/// (`derive_summary`) so list and detail agree.
+pub fn list_invoices_impl(conn: &Connection) -> Result<Vec<InvoiceSummary>, String> {
+    let today = today_ist();
     let mut stmt = conn
         .prepare(
-            "SELECT id, number, invoice_date, due_date, client_name, total, status, created_at
-             FROM invoices ORDER BY id DESC",
+            "SELECT i.id, i.number, i.invoice_date, i.due_date, i.client_name, i.total, i.status,
+                    i.created_at, i.po_number, COALESCE(p.paid, 0), COALESCE(p.tds, 0)
+             FROM invoices i
+             LEFT JOIN (SELECT invoice_id, SUM(amount_paise) AS paid, SUM(tds_paise) AS tds
+                        FROM payments GROUP BY invoice_id) p ON p.invoice_id = i.id
+             ORDER BY i.id DESC",
         )
         .map_err(|e| e.to_string())?;
     let rows = stmt
         .query_map([], |row| {
+            let total: f64 = row.get(5)?;
+            let status: String = row.get(6)?;
+            let due_date: String = row.get(3)?;
+            let total_paise = gst::rupees_to_paise(total);
+            let payment = derive_summary(&status, total_paise, row.get(9)?, row.get(10)?, &due_date, &today);
             Ok(InvoiceSummary {
                 id: row.get(0)?,
                 number: row.get(1)?,
                 invoice_date: row.get(2)?,
-                due_date: row.get(3)?,
+                due_date,
                 client_name: row.get(4)?,
-                total: row.get(5)?,
-                status: row.get(6)?,
+                total,
+                status,
                 created_at: row.get(7)?,
+                po_number: row.get(8)?,
+                total_paise,
+                payment,
             })
         })
         .map_err(|e| e.to_string())?
@@ -516,10 +546,14 @@ pub fn list_invoices(state: State<AppState>) -> Result<Vec<InvoiceSummary>, Stri
     Ok(rows)
 }
 
+pub fn get_invoice_impl(conn: &Connection, id: i64) -> Result<Invoice, String> {
+    fetch_invoice(conn, id).map_err(|e| e.to_string())
+}
+
 #[tauri::command]
 pub fn get_invoice(state: State<AppState>, id: i64) -> Result<Invoice, String> {
     let conn = state.db.lock().map_err(|e| e.to_string())?;
-    fetch_invoice(&conn, id).map_err(|e| e.to_string())
+    get_invoice_impl(&conn, id)
 }
 
 pub fn save_draft_impl(

src-tauri/src/commands/mod.rs

@@ -5,6 +5,7 @@ pub mod files;
 pub mod fonts;
 pub mod invoice;
 pub mod logo;
+pub mod payments;
 pub mod presets;
 pub mod raw;
 pub mod series;

src-tauri/src/commands/payments.rs

@@ -0,0 +1,454 @@
+//! Payments received against issued invoices.
+//!
+//! Money is integer paise throughout. Payment status is never stored: it is derived from the
+//! payment rows, the invoice total and the due date, so deleting a payment reverts it for free.
+//! The issued invoice row is not touched by any of this.
+
+use crate::gst::rupees_to_paise;
+use crate::models::PaymentSummary;
+use crate::AppState;
+use chrono::{FixedOffset, NaiveDate, Utc};
+use rusqlite::{params, Connection, OptionalExtension};
+use serde::{Deserialize, Serialize};
+use tauri::State;
+
+const MODES: &[&str] = &["bank_transfer", "upi", "cash", "cheque", "other"];
+/// Upper bound on one payment (paise); keeps sums far from i64 overflow.
+const MAX_PAISE: i64 = 100_000_000_000;
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct Payment {
+    pub id: i64,
+    pub invoice_id: i64,
+    pub paid_on: String,
+    /// Cash received.
+    pub amount_paise: i64,
+    /// Tax deducted at source by the client; settles the invoice like cash does.
+    pub tds_paise: i64,
+    pub mode: String,
+    pub reference: String,
+    pub notes: String,
+    pub created_at: String,
+}
+
+#[derive(Debug, Clone, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct PaymentInput {
+    pub invoice_id: i64,
+    pub paid_on: String,
+    pub amount_paise: i64,
+    #[serde(default)]
+    pub tds_paise: i64,
+    pub mode: String,
+    #[serde(default)]
+    pub reference: String,
+    #[serde(default)]
+    pub notes: String,
+}
+
+/// Today's date in India (IST, UTC+05:30), as YYYY-MM-DD. Due dates are plain calendar dates.
+pub fn today_ist() -> String {
+    let ist = FixedOffset::east_opt(5 * 3600 + 1800).expect("valid offset");
+    Utc::now().with_timezone(&ist).date_naive().format("%Y-%m-%d").to_string()
+}
+
+/// Derives the payment summary. Only an issued invoice takes payments; anything else is `none`
+/// with a zero balance (a cancelled invoice is owed nothing). `settled` is cash plus TDS.
+/// Overdue means a due date strictly before `today` while a balance remains; it wins over
+/// `partially_paid`, and the paid amounts still show the partial payment.
+pub fn derive_summary(
+    status: &str,
+    total_paise: i64,
+    paid_paise: i64,
+    tds_paise: i64,
+    due_date: &str,
+    today: &str,
+) -> PaymentSummary {
+    if status != "issued" {
+        return PaymentSummary {
+            paid_paise,
+            tds_paise,
+            balance_paise: 0,
+            payment_status: "none".to_string(),
+        };
+    }
+    let settled = paid_paise + tds_paise;
+    let balance = (total_paise - settled).max(0);
+    let overdue = balance > 0
+        && NaiveDate::parse_from_str(due_date.trim(), "%Y-%m-%d").is_ok()
+        && due_date.trim() < today;
+    let payment_status = if balance == 0 && total_paise > 0 {
+        "paid"
+    } else if overdue {
+        "overdue"
+    } else if settled > 0 {
+        "partially_paid"
+    } else {
+        "unpaid"
+    };
+    PaymentSummary {
+        paid_paise,
+        tds_paise,
+        balance_paise: balance,
+        payment_status: payment_status.to_string(),
+    }
+}
+
+/// Summary for one invoice read from the payments table.
+pub fn summary_for(
+    conn: &Connection,
+    invoice_id: i64,
+    status: &str,
+    total: f64,
+    due_date: &str,
+) -> rusqlite::Result<PaymentSummary> {
+    let (paid, tds): (i64, i64) = conn.query_row(
+        "SELECT COALESCE(SUM(amount_paise), 0), COALESCE(SUM(tds_paise), 0)
+         FROM payments WHERE invoice_id = ?1",
+        params![invoice_id],
+        |r| Ok((r.get(0)?, r.get(1)?)),
+    )?;
+    Ok(derive_summary(status, rupees_to_paise(total), paid, tds, due_date, &today_ist()))
+}
+
+fn rupees(paise: i64) -> String {
+    format!("₹{}.{:02}", paise / 100, paise % 100)
+}
+
+fn map_payment(r: &rusqlite::Row) -> rusqlite::Result<Payment> {
+    Ok(Payment {
+        id: r.get(0)?,
+        invoice_id: r.get(1)?,
+        paid_on: r.get(2)?,
+        amount_paise: r.get(3)?,
+        tds_paise: r.get(4)?,
+        mode: r.get(5)?,
+        reference: r.get(6)?,
+        notes: r.get(7)?,
+        created_at: r.get(8)?,
+    })
+}
+
+const COLS: &str = "id, invoice_id, paid_on, amount_paise, tds_paise, mode, reference, notes, created_at";
+
+pub fn record_payment_impl(conn: &mut Connection, input: PaymentInput) -> Result<Payment, String> {
+    let db = |e: rusqlite::Error| e.to_string();
+
+    NaiveDate::parse_from_str(input.paid_on.trim(), "%Y-%m-%d")
+        .map_err(|_| "Payment date must be a date like 2026-04-01".to_string())?;
+    if !MODES.contains(&input.mode.as_str()) {
+        return Err(format!("Unknown payment mode \"{}\"", input.mode));
+    }
+    if input.amount_paise < 0 || input.tds_paise < 0 {
+        return Err("Amounts cannot be negative".into());
+    }
+    if input.amount_paise > MAX_PAISE || input.tds_paise > MAX_PAISE {
+        return Err("That amount is too large".into());
+    }
+    if input.amount_paise + input.tds_paise == 0 {
+        return Err("Enter an amount received or TDS deducted".into());
+    }
+
+    let tx = conn.transaction().map_err(db)?;
+    let (status, total): (String, f64) = tx
+        .query_row(
+            "SELECT status, total FROM invoices WHERE id = ?1",
+            params![input.invoice_id],
+            |r| Ok((r.get(0)?, r.get(1)?)),
+        )
+        .optional()
+        .map_err(db)?
+        .ok_or_else(|| "Invoice not found".to_string())?;
+    if status != "issued" {
+        return Err(format!("Payments can only be recorded on an issued invoice (this one is {status})"));
+    }
+    let total_paise = rupees_to_paise(total);
+    let settled: i64 = tx
+        .query_row(
+            "SELECT COALESCE(SUM(amount_paise + tds_paise), 0) FROM payments WHERE invoice_id = ?1",
+            params![input.invoice_id],
+            |r| r.get(0),
+        )
+        .map_err(db)?;
+    let balance = total_paise - settled;
+    let incoming = input.amount_paise + input.tds_paise;
+    if incoming > balance {
+        return Err(format!(
+            "This payment of {} (cash plus TDS) is more than the outstanding balance of {}",
+            rupees(incoming),
+            rupees(balance.max(0))
+        ));
+    }
+
+    let now = chrono::Utc::now().to_rfc3339();
+    tx.execute(
+        "INSERT INTO payments (invoice_id, paid_on, amount_paise, tds_paise, mode, reference, notes, created_at)
+         VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8)",
+        params![
+            input.invoice_id,
+            input.paid_on.trim(),
+            input.amount_paise,
+            input.tds_paise,
+            input.mode,
+            input.reference.trim(),
+            input.notes.trim(),
+            now
+        ],
+    )
+    .map_err(db)?;
+    let id = tx.last_insert_rowid();
+    let payment = tx
+        .query_row(&format!("SELECT {COLS} FROM payments WHERE id = ?1"), params![id], map_payment)
+        .map_err(db)?;
+    tx.commit().map_err(db)?;
+    Ok(payment)
+}
+
+pub fn list_payments_impl(conn: &Connection, invoice_id: i64) -> Result<Vec<Payment>, String> {
+    let mut stmt = conn
+        .prepare(&format!(
+            "SELECT {COLS} FROM payments WHERE invoice_id = ?1 ORDER BY paid_on ASC, id ASC"
+        ))
+        .map_err(|e| e.to_string())?;
+    let rows = stmt
+        .query_map(params![invoice_id], map_payment)
+        .map_err(|e| e.to_string())?
+        .collect::<rusqlite::Result<Vec<_>>>()
+        .map_err(|e| e.to_string())?;
+    Ok(rows)
+}
+
+pub fn delete_payment_impl(conn: &Connection, id: i64) -> Result<(), String> {
+    let changed = conn
+        .execute("DELETE FROM payments WHERE id = ?1", params![id])
+        .map_err(|e| e.to_string())?;
+    if changed == 0 {
+        return Err("Payment not found".into());
+    }
+    Ok(())
+}
+
+#[tauri::command]
+pub fn record_payment(state: State<AppState>, input: PaymentInput) -> Result<Payment, String> {
+    let mut conn = state.db.lock().map_err(|e| e.to_string())?;
+    record_payment_impl(&mut conn, input)
+}
+
+#[tauri::command]
+pub fn list_payments(state: State<AppState>, invoice_id: i64) -> Result<Vec<Payment>, String> {
+    let conn = state.db.lock().map_err(|e| e.to_string())?;
+    list_payments_impl(&conn, invoice_id)
+}
+
+#[tauri::command]
+pub fn delete_payment(state: State<AppState>, id: i64) -> Result<(), String> {
+    let conn = state.db.lock().map_err(|e| e.to_string())?;
+    delete_payment_impl(&conn, id)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::commands::invoice::{cancel_invoice_impl, issue_invoice_impl};
+    use crate::models::InvoiceInput;
+    use serde_json::json;
+    use std::path::Path;
+
+    /// An unregistered vendor issues without tax, so the invoice total is exactly the line amount.
+    fn issued(conn: &mut Connection, amount: f64, due: &str) -> i64 {
+        let input: InvoiceInput = serde_json::from_value(json!({
+            "invoiceDate": "2026-04-01",
+            "dueDate": due,
+            "clientName": "Client Ltd",
+            "taxType": "none",
+            "taxRate": 0.0,
+            "items": [{"description": "Design", "mode": "fixed", "amount": amount}],
+        }))
+        .unwrap();
+        issue_invoice_impl(conn, Path::new("/nonexistent"), input, &json!({})).unwrap().id
+    }
+
+    fn pay(invoice_id: i64, amount: i64, tds: i64) -> PaymentInput {
+        PaymentInput {
+            invoice_id,
+            paid_on: "2026-04-10".into(),
+            amount_paise: amount,
+            tds_paise: tds,
+            mode: "bank_transfer".into(),
+            reference: "UTR1".into(),
+            notes: String::new(),
+        }
+    }
+
+    fn summary(conn: &Connection, id: i64) -> PaymentSummary {
+        let (status, total, due): (String, f64, String) = conn
+            .query_row("SELECT status, total, due_date FROM invoices WHERE id = ?1", params![id], |r| {
+                Ok((r.get(0)?, r.get(1)?, r.get(2)?))
+            })
+            .unwrap();
+        summary_for(conn, id, &status, total, &due).unwrap()
+    }
+
+    #[test]
+    fn partial_then_full_payment_settles() {
+        let mut conn = crate::db::open_in_memory().unwrap();
+        let id = issued(&mut conn, 1000.0, "2999-01-01");
+        assert_eq!(summary(&conn, id).payment_status, "unpaid");
+        assert_eq!(summary(&conn, id).balance_paise, 100_000);
+
+        record_payment_impl(&mut conn, pay(id, 40_000, 0)).unwrap();
+        let s = summary(&conn, id);
+        assert_eq!((s.payment_status.as_str(), s.paid_paise, s.balance_paise), ("partially_paid", 40_000, 60_000));
+
+        record_payment_impl(&mut conn, pay(id, 60_000, 0)).unwrap();
+        let s = summary(&conn, id);
+        assert_eq!((s.payment_status.as_str(), s.balance_paise), ("paid", 0));
+    }
+
+    #[test]
+    fn tds_counts_towards_settling() {
+        let mut conn = crate::db::open_in_memory().unwrap();
+        let id = issued(&mut conn, 1000.0, "2999-01-01");
+        // 10% TDS: the client pays 900.00 in cash and deducts 100.00.
+        record_payment_impl(&mut conn, pay(id, 90_000, 10_000)).unwrap();
+        let s = summary(&conn, id);
+        assert_eq!((s.payment_status.as_str(), s.paid_paise, s.tds_paise, s.balance_paise), ("paid", 90_000, 10_000, 0));
+        // TDS alone is a valid payment too.
+        let id2 = issued(&mut conn, 500.0, "2999-01-01");
+        record_payment_impl(&mut conn, pay(id2, 0, 5_000)).unwrap();
+        assert_eq!(summary(&conn, id2).payment_status, "partially_paid");
+    }
+
+    #[test]
+    fn overpayment_is_rejected_including_tds() {
+        let mut conn = crate::db::open_in_memory().unwrap();
+        let id = issued(&mut conn, 1000.0, "2999-01-01");
+        let err = record_payment_impl(&mut conn, pay(id, 100_001, 0)).unwrap_err();
+        assert!(err.contains("more than the outstanding balance of ₹1000.00"), "{err}");
+        // Cash plus TDS is what counts.
+        assert!(record_payment_impl(&mut conn, pay(id, 95_000, 6_000)).is_err());
+        record_payment_impl(&mut conn, pay(id, 50_000, 0)).unwrap();
+        let err = record_payment_impl(&mut conn, pay(id, 50_001, 0)).unwrap_err();
+        assert!(err.contains("₹500.00"), "{err}");
+        let n: i64 = conn.query_row("SELECT COUNT(*) FROM payments", [], |r| r.get(0)).unwrap();
+        assert_eq!(n, 1);
+    }
+
+    #[test]
+    fn invalid_input_is_rejected() {
+        let mut conn = crate::db::open_in_memory().unwrap();
+        let id = issued(&mut conn, 1000.0, "2999-01-01");
+        assert!(record_payment_impl(&mut conn, pay(id, 0, 0)).is_err());
+        assert!(record_payment_impl(&mut conn, pay(id, -1, 0)).is_err());
+        assert!(record_payment_impl(&mut conn, pay(id, 100, -5)).is_err());
+        let mut bad = pay(id, 100, 0);
+        bad.mode = "barter".into();
+        assert!(record_payment_impl(&mut conn, bad).is_err());
+        let mut bad = pay(id, 100, 0);
+        bad.paid_on = "10/04/2026".into();
+        assert!(record_payment_impl(&mut conn, bad).is_err());
+        assert!(record_payment_impl(&mut conn, pay(9999, 100, 0)).is_err());
+        // The table CHECKs hold even if a caller bypasses the command validation.
+        assert!(conn
+            .execute(
+                "INSERT INTO payments (invoice_id, paid_on, amount_paise, tds_paise, mode, created_at)
+                 VALUES (?1, '2026-04-10', 0, 0, 'cash', 'now')",
+                params![id]
+            )
+            .is_err());
+    }
+
+    #[test]
+    fn draft_and_cancelled_invoices_take_no_payments() {
+        let mut conn = crate::db::open_in_memory().unwrap();
+        let id = issued(&mut conn, 1000.0, "2999-01-01");
+        cancel_invoice_impl(&mut conn, id, "mistake").unwrap();
+        let err = record_payment_impl(&mut conn, pay(id, 100, 0)).unwrap_err();
+        assert!(err.contains("issued invoice"), "{err}");
+        let s = summary(&conn, id);
+        assert_eq!((s.payment_status.as_str(), s.balance_paise), ("none", 0));
+
+        let id2 = issued(&mut conn, 1000.0, "2999-01-01");
+        conn.execute("UPDATE invoices SET status = 'draft' WHERE id = ?1", params![id2]).unwrap();
+        assert!(record_payment_impl(&mut conn, pay(id2, 100, 0)).is_err());
+    }
+
+    #[test]
+    fn an_invoice_with_payments_cannot_be_cancelled() {
+        let mut conn = crate::db::open_in_memory().unwrap();
+        let id = issued(&mut conn, 1000.0, "2999-01-01");
+        let p = record_payment_impl(&mut conn, pay(id, 100, 0)).unwrap();
+        let err = cancel_invoice_impl(&mut conn, id, "").unwrap_err();
+        assert!(err.contains("payments"), "{err}");
+        delete_payment_impl(&conn, p.id).unwrap();
+        cancel_invoice_impl(&mut conn, id, "").unwrap();
+    }
+
+    #[test]
+    fn deleting_a_payment_reverts_the_status() {
+        let mut conn = crate::db::open_in_memory().unwrap();
+        let id = issued(&mut conn, 1000.0, "2999-01-01");
+        let full = record_payment_impl(&mut conn, pay(id, 100_000, 0)).unwrap();
+        assert_eq!(summary(&conn, id).payment_status, "paid");
+        delete_payment_impl(&conn, full.id).unwrap();
+        let s = summary(&conn, id);
+        assert_eq!((s.payment_status.as_str(), s.balance_paise), ("unpaid", 100_000));
+        assert!(list_payments_impl(&conn, id).unwrap().is_empty());
+        assert!(delete_payment_impl(&conn, full.id).is_err());
+    }
+
+    #[test]
+    fn overdue_is_derived_from_due_date_and_balance() {
+        let d = |due: &str, paid: i64, tds: i64| derive_summary("issued", 100_000, paid, tds, due, "2026-05-10");
+        // Due today is not overdue yet; the day after is.
+        assert_eq!(d("2026-05-10", 0, 0).payment_status, "unpaid");
+        assert_eq!(d("2026-05-09", 0, 0).payment_status, "overdue");
+        // Overdue wins over partially paid; the paid amount is still reported.
+        let s = d("2026-05-09", 10_000, 0);
+        assert_eq!((s.payment_status.as_str(), s.paid_paise), ("overdue", 10_000));
+        // A settled invoice is never overdue.
+        assert_eq!(d("2026-05-09", 90_000, 10_000).payment_status, "paid");
+        // No usable due date means never overdue.
+        assert_eq!(d("", 0, 0).payment_status, "unpaid");
+        assert_eq!(d("not a date", 0, 0).payment_status, "unpaid");
+        // Cancelled invoices are not owed.
+        assert_eq!(derive_summary("cancelled", 100_000, 0, 0, "2020-01-01", "2026-05-10").balance_paise, 0);
+    }
+
+    #[test]
+    fn totals_are_integer_paise_without_float_drift() {
+        let mut conn = crate::db::open_in_memory().unwrap();
+        // 0.1 + 0.2 style amounts: 3 x 33.33 = 99.99.
+        let id = issued(&mut conn, 99.99, "2999-01-01");
+        record_payment_impl(&mut conn, pay(id, 3333, 0)).unwrap();
+        record_payment_impl(&mut conn, pay(id, 3333, 0)).unwrap();
+        record_payment_impl(&mut conn, pay(id, 3333, 0)).unwrap();
+        let s = summary(&conn, id);
+        assert_eq!((s.paid_paise, s.balance_paise, s.payment_status.as_str()), (9999, 0, "paid"));
+        let inv = super::super::invoice::get_invoice_impl(&conn, id).unwrap();
+        assert_eq!(inv.total_paise, 9999);
+    }
+
+    #[test]
+    fn list_invoices_joins_the_payment_sums() {
+        let mut conn = crate::db::open_in_memory().unwrap();
+        let a = issued(&mut conn, 1000.0, "2020-01-01");
+        let b = issued(&mut conn, 200.0, "2999-01-01");
+        record_payment_impl(&mut conn, pay(a, 30_000, 5_000)).unwrap();
+        record_payment_impl(&mut conn, pay(a, 10_000, 0)).unwrap();
+        record_payment_impl(&mut conn, pay(b, 20_000, 0)).unwrap();
+        let rows = super::super::invoice::list_invoices_impl(&conn).unwrap();
+        let get = |id: i64| rows.iter().find(|r| r.id == id).unwrap();
+        let ra = get(a);
+        assert_eq!((ra.payment.paid_paise, ra.payment.tds_paise, ra.payment.balance_paise), (40_000, 5_000, 55_000));
+        assert_eq!(ra.payment.payment_status, "overdue");
+        assert_eq!(ra.total_paise, 100_000);
+        assert_eq!(get(b).payment.payment_status, "paid");
+        // The JSON keeps the existing fields and adds the flattened summary.
+        let json = serde_json::to_value(ra).unwrap();
+        assert_eq!(json["balancePaise"], 55_000);
+        assert_eq!(json["paymentStatus"], "overdue");
+        assert_eq!(json["total"], 1000.0);
+    }
+}

src-tauri/src/db.rs

@@ -10,7 +10,7 @@ const MAX_BACKUPS: usize = 10;
 const BACKUP_PREFIX: &str = "voiced-pre-v";
 
 /// Highest schema version, i.e. the number of entries in `migrations()`.
-const LATEST_VERSION: i64 = 7;
+const LATEST_VERSION: i64 = 8;
 
 #[derive(Debug, thiserror::Error)]
 pub enum DbError {
@@ -245,8 +245,36 @@ CREATE TABLE item_presets (
 );
 "#;
 
+/// Version 8: payments received against issued invoices. Amounts are integer paise. `amount_paise` is the cash
+/// received and `tds_paise` the tax the client deducted at source; both count towards settling the invoice.
+/// Payment status is derived from these rows and the due date, never stored, and the issued invoice row is untouched.
+const M8: &str = r#"
+CREATE TABLE payments (
+    id           INTEGER PRIMARY KEY AUTOINCREMENT,
+    invoice_id   INTEGER NOT NULL REFERENCES invoices(id),
+    paid_on      TEXT NOT NULL,
+    amount_paise INTEGER NOT NULL DEFAULT 0 CHECK (amount_paise >= 0),
+    tds_paise    INTEGER NOT NULL DEFAULT 0 CHECK (tds_paise >= 0),
+    mode         TEXT NOT NULL CHECK (mode IN ('bank_transfer', 'upi', 'cash', 'cheque', 'other')),
+    reference    TEXT NOT NULL DEFAULT '',
+    notes        TEXT NOT NULL DEFAULT '',
+    created_at   TEXT NOT NULL,
+    CHECK (amount_paise + tds_paise > 0)
+);
+CREATE INDEX idx_payments_invoice ON payments(invoice_id);
+"#;
+
 fn migrations() -> Migrations<'static> {
-    Migrations::new(vec![M::up(SCHEMA), M::up(M2), M::up(M3), M::up(M4), M::up(M5), M::up(M6), M::up(M7)])
+    Migrations::new(vec![
+        M::up(SCHEMA),
+        M::up(M2),
+        M::up(M3),
+        M::up(M4),
+        M::up(M5),
+        M::up(M6),
+        M::up(M7),
+        M::up(M8),
+    ])
 }
 
 /// Open (creating if needed) the database at `path` and bring it to the latest schema.
@@ -725,7 +753,7 @@ CREATE INDEX IF NOT EXISTS idx_invoices_created ON invoices(created_at DESC);
         .unwrap();
 
         migrations().to_latest(&mut conn).unwrap();
-        assert_eq!(user_version(&conn), 7);
+        assert_eq!(user_version(&conn), LATEST_VERSION);
 
         type Row = (String, String, String, String, String, String, String);
         let rows: Vec<Row> = conn

src-tauri/src/lib.rs

@@ -133,6 +133,9 @@ pub fn run() {
             commands::invoice::list_drafts,
             commands::invoice::get_draft,
             commands::invoice::delete_draft,
+            commands::payments::record_payment,
+            commands::payments::list_payments,
+            commands::payments::delete_payment,
             commands::assets::import_asset,
             commands::assets::save_asset_bytes,
             commands::assets::read_asset_data_uri,

src-tauri/src/models.rs

@@ -265,6 +265,34 @@ pub struct Invoice {
     pub archived_fingerprint: Option<String>,
     pub archived_at: Option<String>,
     pub items: Vec<InvoiceItem>,
+    /// Derived from the payments table (never stored on the invoice): see commands::payments.
+    #[serde(flatten)]
+    pub payment: PaymentSummary,
+    /// `total` in integer paise.
+    #[serde(default)]
+    pub total_paise: i64,
+}
+
+/// What has been received against an invoice. All amounts are integer paise; `payment_status` is
+/// unpaid | partially_paid | paid | overdue, or `none` for an invoice that takes no payments.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct PaymentSummary {
+    pub paid_paise: i64,
+    pub tds_paise: i64,
+    pub balance_paise: i64,
+    pub payment_status: String,
+}
+
+impl Default for PaymentSummary {
+    fn default() -> Self {
+        PaymentSummary {
+            paid_paise: 0,
+            tds_paise: 0,
+            balance_paise: 0,
+            payment_status: "none".to_string(),
+        }
+    }
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -278,6 +306,10 @@ pub struct InvoiceSummary {
     pub total: f64,
     pub status: String,
     pub created_at: String,
+    pub po_number: String,
+    pub total_paise: i64,
+    #[serde(flatten)]
+    pub payment: PaymentSummary,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]