fix(ledger): preserve exact decimal amount in manual and unified responses

Co-authored-by: genichin <4282227+genichin@users.noreply.github.com>

tests/test_v1_portfolios_manual_ledger.py

@@ -199,6 +199,7 @@ class _FakeRepo:
             side=action.lower(),
             quantity=quantity,
             price=price,
+            price_decimal=amount_decimal if action == "DIVIDEND" else Decimal(str(price)),
             fee_amount=fee,
             tax_amount=tax,
             executed_at=executed_at,
@@ -505,7 +506,7 @@ def test_dividend_updates_only_profit_buffer_and_records_executed_at_and_tax() -
     assert resp.status_code == 201
     body = resp.json()
     assert body["action"] == "DIVIDEND"
-    assert body["amount"] == 120.0
+    assert body["amount"] == "120"
     assert body["tax"] == 10.0
     assert body["executed_at"] == "2026-09-01T00:00:00Z"
     assert body["cash_balance_after"] == 1000.0
@@ -593,11 +594,14 @@ def test_dividend_rejects_invalid_amount_tax_and_unrelated_fields_without_state_
     )
 
     invalid_payloads = [
+        {"action": "DIVIDEND", "amount": 1},
         {"action": "DIVIDEND", "amount": 0, "executed_at": "2026-09-01"},
         {"action": "DIVIDEND", "amount": -1, "executed_at": "2026-09-01"},
+        {"action": "DIVIDEND", "amount": 1, "executed_at": "2026-13-40"},
         {"action": "DIVIDEND", "amount": 1, "tax": -1, "executed_at": "2026-09-01"},
         {"action": "DIVIDEND", "amount": 1, "tax": "0.000000001", "executed_at": "2026-09-01"},
         {"action": "DIVIDEND", "amount": 1, "tax": "1000000000000.00000000", "executed_at": "2026-09-01"},
+        {"action": "DIVIDEND", "amount": 1, "executed_at": "2026-09-01", "fee": 0},
         {"action": "DIVIDEND", "amount": 1, "executed_at": "2026-09-01", "quantity": 1},
         {"action": "DIVIDEND", "amount": 1, "executed_at": "2026-09-01", "price": 1},
         {"action": "DIVIDEND", "amount": 1, "executed_at": "2026-09-01", "target_ledger_entry_id": 1},
@@ -712,6 +716,14 @@ def test_dividend_duplicate_check_does_not_collapse_decimals_that_can_alias_in_f
         headers=_auth(),
     )
     assert second.status_code == 201
+    assert first.json()["amount"] == "90000000.00000001"
+    assert second.json()["amount"] == "90000000.00000002"
+
+    history = client.get(f"/v1/portfolios/{_PORTFOLIO_ID}/ledger?source=manual", headers=_auth())
+    assert history.status_code == 200
+    amounts = [item["amount"] for item in history.json()["items"] if item["action"] == "DIVIDEND"]
+    assert "90000000.00000001" in amounts
+    assert "90000000.00000002" in amounts
 
 
 def test_reversed_dividend_is_excluded_from_future_duplicate_candidate_matching() -> None:
@@ -891,7 +903,7 @@ def test_unified_ledger_includes_dividend_fields() -> None:
     item = resp.json()["items"][0]
     assert item["source"] == "manual"
     assert item["action"] == "DIVIDEND"
-    assert item["amount"] == 33.0
+    assert item["amount"] == "33"
     assert item["price"] == 33.0
     assert item["executed_at"] == "2026-09-01T00:00:00Z"
     assert item["tax_amount"] == 3.0