From 2926d6081863e7d32f5e0fc9320cf06b7a739032 Mon Sep 17 00:00:00 2001
From: Sandeep Somasekharan <codereverser@gmail.com>
Date: Wed, 24 Jun 2026 22:41:21 +1000
Subject: [PATCH] fix: classify STP as switch across both RTAs (discussion
 #141)

---
 CHANGELOG.md                   |  7 +++++++
 casparser/__init__.py          |  2 +-
 casparser/parsers/_classify.py | 13 +++++++++++--
 tests/test_helpers.py          | 33 +++++++++++++++++++++++++++++++++
 4 files changed, 52 insertions(+), 3 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4cd7f66..0d5255e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,12 @@
 # Changelog
 
+## 1.2.1
+
+### Fixed
+
+- Fix mis-classification of STP (Systematic Transfer Plan) for
+  Kfintech-serviced schemes. (discussion #141)
+
 ## 1.2.0
 
 ### New
diff --git a/casparser/__init__.py b/casparser/__init__.py
index b106f27..19ccb3b 100644
--- a/casparser/__init__.py
+++ b/casparser/__init__.py
@@ -9,4 +9,4 @@
     "CapitalGainsReport",
 ]
 
-__version__ = "1.2.0"
+__version__ = "1.2.1"
diff --git a/casparser/parsers/_classify.py b/casparser/parsers/_classify.py
index f92a055..52baa1f 100644
--- a/casparser/parsers/_classify.py
+++ b/casparser/parsers/_classify.py
@@ -37,6 +37,15 @@
 )
 REINVEST_RE = re.compile(r"reinvest", re.I)
 
+# Systematic Transfer Plan. A switch by another name — money is moved
+# between two schemes on a schedule. The two RTAs word it differently:
+# CAMS prints "Systematic Transfer Plan Switch In/Out …" (already caught by
+# the "switch" keyword), while KFintech prints it letter-spaced as
+# "S T P In/Out (…)", which matches none of the plain substring checks and
+# used to fall through to PURCHASE / REDEMPTION. Detecting it here — spacing
+# tolerated — lets both RTAs classify consistently as SWITCH_IN / SWITCH_OUT.
+STP_RE = re.compile(r"\bs\s*t\s*p\b|systematic\s+transfer", re.I)
+
 # Counterparty folio embedded in a gift transfer description. Both RTAs
 # name the other folio but punctuate differently — KFin uses a colon
 # ("Folio No: 12345678901"), CAMS a dot ("Folio No.87654321") — so accept
@@ -82,7 +91,7 @@ def get_transaction_type(
     elif units > 0:
         if "gift" in description:
             txn_type = TransactionType.GIFT_IN
-        elif "switch" in description:
+        elif "switch" in description or STP_RE.search(description):
             txn_type = (
                 TransactionType.SWITCH_IN_MERGER
                 if "merger" in description
@@ -109,7 +118,7 @@ def get_transaction_type(
             re.I,
         ):
             txn_type = TransactionType.REVERSAL
-        elif "switch" in description:
+        elif "switch" in description or STP_RE.search(description):
             txn_type = (
                 TransactionType.SWITCH_OUT_MERGER
                 if "merger" in description
diff --git a/tests/test_helpers.py b/tests/test_helpers.py
index 8adb91f..56e334f 100644
--- a/tests/test_helpers.py
+++ b/tests/test_helpers.py
@@ -119,6 +119,39 @@ def test_gifts(self):
             Decimal("4085.662"),
         ) == (TransactionType.GIFT_IN, None)
 
+    def test_stp(self):
+        # Systematic Transfer Plan legs must classify as SWITCH_OUT (source,
+        # negative units) / SWITCH_IN (target, positive units) regardless of
+        # how the RTA words them. CAMS spells it out ("Systematic Transfer
+        # Plan Switch …", already caught by the "switch" keyword); KFintech
+        # prints it letter-spaced as "S T P In/Out", which previously fell
+        # through to PURCHASE / REDEMPTION. (discussion #141)
+        assert get_transaction_type(
+            "Systematic Transfer Plan Switch Out - To SBI Small Cap Fund Dir Growth-",
+            Decimal("-5.938"),
+        ) == (TransactionType.SWITCH_OUT, None)
+        assert get_transaction_type(
+            "Systematic Transfer Plan Switch In - From SBI Liquid Fund Direct Growth-",
+            Decimal("126.972"),
+        ) == (TransactionType.SWITCH_IN, None)
+        # KFintech, letter-spaced.
+        assert get_transaction_type(
+            "S T P Out (To Axis Mid Cap Fund - Direct Growth F.No:91064932471)",
+            Decimal("-24.933"),
+        ) == (TransactionType.SWITCH_OUT, None)
+        assert get_transaction_type(
+            "S T P In (From Axis Liquid Fund - Direct Growth F.No:91064932471)",
+            Decimal("571.574"),
+        ) == (TransactionType.SWITCH_IN, None)
+
+    def test_sip_not_misread_as_stp(self):
+        # A genuine SIP must stay PURCHASE_SIP — the STP detection must not
+        # swallow "Systematic Investment" or the "SIP" token.
+        assert get_transaction_type(
+            "Systematic Investment-Instalment No 12",
+            Decimal("10"),
+        ) == (TransactionType.PURCHASE_SIP, None)
+
     def test_dividends(self):
         assert get_transaction_type(
             "IDCW Reinvestment @ Rs.2.00 per unit",