invoice: allow setting the bankgiro, document wave 1

3 files changed, 19 insertions, 2 deletions

diff --git a/docs/INVOICING.md b/docs/INVOICING.md
index f509997..7c6ce2e 100644
--- a/docs/INVOICING.md
+++ b/docs/INVOICING.md
@@ -149,7 +149,8 @@ form (draft in the TUI)
 
 - Default bank/receivable account `1510` (setting `invoice_receivable_account`).
 - Revenue account per line, default from setting `invoice_revenue_account`
-  (`3001`), overridable per row.
+  (`3001`), overridable per row. The seller's payment reference comes from
+  setting `invoice_bankgiro` (e.g. `5750-4144`).
 - VAT per row via `vat_code`: `25`, `12`, `6`, `0`, `rc` (omvänd
   skattskyldighet, no VAT on the invoice, `Momsfritt` in the summary) and
   `eu` (EU sale, `Momsfritt`).
diff --git a/docs/STATE.md b/docs/STATE.md
index 428bb79..8c6eaa3 100644
--- a/docs/STATE.md
+++ b/docs/STATE.md
@@ -148,6 +148,16 @@ check.
     real PDF without consuming the number, and SMTP sending with the
     password encrypted in the DB (AES-256-GCM, `BOKFD_SECRET_KEY`).
     Implementation waves: schema v9 + PDF, SMTP, TUI (Fakturering).
+    **Wave 1 done 2026-09-20**: schema v9 (`customers`, `invoice_sequence`,
+    `invoices`, `invoice_rows`, widened `vouchers.source` with a table
+    rebuild), the PDF renderer (`src/invoice.c`, 2.2 % raw pixel diff vs the
+    Google Sheets original — all structure exact; only Arial-vs-Helvetica
+    glyphs differ), and `customer.*`, `invoice.sequence_get/set`,
+    `invoice.preview/issue/list/get/pdf`. Issue is atomic: number + PDF
+    attachment + voucher (D 1510/K 3xxx+26xx, `source:"invoice"`) + links.
+    Settings `invoice_receivable_account`, `invoice_revenue_account`,
+    `invoice_bankgiro`. **Open detail: invoice 1 (Andrabygg) carries a Swish
+    QR image — decide whether the generator should support one.**
 
 ## Pending decisions
 
diff --git a/src/commands.c b/src/commands.c
index 72a8f70..a587ce3 100644
--- a/src/commands.c
+++ b/src/commands.c
@@ -2655,7 +2655,7 @@ static yyjson_mut_val *h_settings_set(struct req *r)
     if (!key || !value)
         return fail(r, "INVALID_ARGS", "key and value are required");
     size_t maxlen;
-    int digits_only = 0;
+    int digits_only = 0, bankgiro = 0;
     if (strcmp(key, "default_series") == 0)
         maxlen = 8;
     else if (strcmp(key, "attachment_dir") == 0)
@@ -2665,6 +2665,9 @@ static yyjson_mut_val *h_settings_set(struct req *r)
              strcmp(key, "invoice_revenue_account") == 0) {
         maxlen = 10;
         digits_only = 1;
+    } else if (strcmp(key, "invoice_bankgiro") == 0) {
+        maxlen = 16;
+        bankgiro = 1;
     } else
         return fail(r, "UNSUPPORTED", "unknown setting");
     size_t len = strlen(value);
@@ -2674,6 +2677,9 @@ static yyjson_mut_val *h_settings_set(struct req *r)
     for (const char *p = value; *p; p++) {
         if (digits_only && (*p < '0' || *p > '9'))
             return failf(r, "INVALID_ARGS", "%s must be digits only", key);
+        if (bankgiro && !((*p >= '0' && *p <= '9') || *p == '-'))
+            return failf(r, "INVALID_ARGS",
+                         "%s must be digits and hyphens", key);
         if ((unsigned char)*p < 32)
             return failf(r, "INVALID_ARGS",
                          "%s must not contain control characters", key);