diff --git a/app/views/api/v1/transactions/_transaction.json.jbuilder b/app/views/api/v1/transactions/_transaction.json.jbuilder
index 2a1c9779e..617f47505 100644
--- a/app/views/api/v1/transactions/_transaction.json.jbuilder
+++ b/app/views/api/v1/transactions/_transaction.json.jbuilder
@@ -3,6 +3,17 @@
 json.id transaction.id
 json.date transaction.entry.date
 json.amount transaction.entry.amount_money.format
+
+# Agent/automation-friendly numeric fields (avoid localized parsing and clarify sign)
+# `amount` in v1 is a localized string and may follow an accounting sign convention.
+# Expose minor units (cents) as integers to make the API agent-friendly.
+# Uses currency.minor_unit_conversion (e.g. 100 for USD/EUR, 1 for JPY, 1000 for KWD).
+amount_money = transaction.entry.amount_money
+conversion_factor = amount_money.currency.minor_unit_conversion
+amount_cents = (amount_money.amount * conversion_factor).round(0).to_i.abs
+json.amount_cents amount_cents
+json.signed_amount_cents(transaction.entry.classification == "income" ? amount_cents : -amount_cents)
+
 json.currency transaction.entry.currency
 json.name transaction.entry.name
 json.notes transaction.entry.notes
diff --git a/test/controllers/api/v1/transactions_controller_test.rb b/test/controllers/api/v1/transactions_controller_test.rb
index b028562a6..9b681d4de 100644
--- a/test/controllers/api/v1/transactions_controller_test.rb
+++ b/test/controllers/api/v1/transactions_controller_test.rb
@@ -41,6 +41,10 @@ class Api::V1::TransactionsControllerTest < ActionDispatch::IntegrationTest
     response_data = JSON.parse(response.body)
     assert response_data.key?("transactions")
     assert response_data.key?("pagination")
+
+    # Agent-friendly numeric fields (validate type + sign invariants)
+    first = response_data["transactions"].first
+    assert_amount_cents_fields(first)
     assert response_data["pagination"].key?("page")
     assert response_data["pagination"].key?("per_page")
     assert response_data["pagination"].key?("total_count")
@@ -130,6 +134,7 @@ class Api::V1::TransactionsControllerTest < ActionDispatch::IntegrationTest
     assert_equal @transaction.id, response_data["id"]
     assert response_data.key?("name")
     assert response_data.key?("amount")
+    assert_amount_cents_fields(response_data)
     assert response_data.key?("date")
     assert response_data.key?("account")
   end
@@ -358,4 +363,22 @@ end
     def api_headers(api_key)
       { "X-Api-Key" => api_key.display_key }
     end
+
+    # Validates agent-friendly numeric fields: type, sign invariants
+    def assert_amount_cents_fields(txn_json)
+      assert txn_json.key?("amount_cents"), "Expected amount_cents field"
+      assert txn_json.key?("signed_amount_cents"), "Expected signed_amount_cents field"
+      assert_kind_of Integer, txn_json["amount_cents"]
+      assert_kind_of Integer, txn_json["signed_amount_cents"]
+      assert_operator txn_json["amount_cents"], :>=, 0, "amount_cents must be non-negative"
+      assert_equal txn_json["amount_cents"].abs, txn_json["signed_amount_cents"].abs,
+                   "Absolute values of amount_cents and signed_amount_cents must match"
+      if txn_json["classification"] == "income"
+        assert_operator txn_json["signed_amount_cents"], :>=, 0,
+                        "income transactions should have non-negative signed_amount_cents"
+      else
+        assert_operator txn_json["signed_amount_cents"], :<=, 0,
+                        "non-income transactions should have non-positive signed_amount_cents"
+      end
+    end
 end