From 6c478f739aa191afedae91174348d75d9fab4366 Mon Sep 17 00:00:00 2001
From: JSap0914 <JSap0914@users.noreply.github.com>
Date: Wed, 17 Jun 2026 15:19:20 +0900
Subject: [PATCH 1/2] Fix IndexError when nested JSON key ends with a trailing
 backslash

tokenize() in httpie/cli/nested_json/parse.py guarded the backslash
branch with `can_advance()`, which tests `cursor < len(source)`.
Because we are already inside the `while can_advance()` loop that
guard is always True, so when the input ends with a backslash the
code immediately tries to read `source[cursor + 1]` and raises

  IndexError: string index out of range

Fix: replace `can_advance()` with `cursor + 1 < len(source)` so
the check actually tests for the existence of the *next* character.
When no next character exists the backslash falls through to the
else-branch and is appended to the buffer as a literal character,
matching the behaviour of KeyValueArgType.tokenize() in argtypes.py.

Adds a regression test that exercises both tokenize() and parse()
with a key ending in a backslash without requiring a live server.
---
 httpie/cli/nested_json/parse.py |  2 +-
 tests/test_json.py              | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/httpie/cli/nested_json/parse.py b/httpie/cli/nested_json/parse.py
index 323a22eef1..5e5a8bb185 100644
--- a/httpie/cli/nested_json/parse.py
+++ b/httpie/cli/nested_json/parse.py
@@ -164,7 +164,7 @@ def can_advance() -> bool:
         if index in OPERATORS:
             yield from send_buffer()
             yield Token(OPERATORS[index], index, cursor, cursor + 1)
-        elif index == BACKSLASH and can_advance():
+        elif index == BACKSLASH and cursor + 1 < len(source):
             if source[cursor + 1] in SPECIAL_CHARS:
                 backslashes += 1
             else:
diff --git a/tests/test_json.py b/tests/test_json.py
index e758ebe7f4..d946794314 100644
--- a/tests/test_json.py
+++ b/tests/test_json.py
@@ -581,3 +581,21 @@ def test_nested_json_errors(input_json, expected_error, httpbin):
 def test_nested_json_sparse_array(httpbin_both):
     r = http(httpbin_both + '/post', 'test[0]:=1', 'test[100]:=1')
     assert len(r.json['json']['test']) == 101
+
+def test_nested_json_trailing_backslash_no_crash():
+    """A backslash at the very end of a key must not crash with IndexError.
+
+    Regression test for: tokenize() accessed source[cursor + 1] without
+    first verifying cursor + 1 < len(source).
+    """
+    from httpie.cli.nested_json.parse import tokenize, parse
+
+    trailing_bs = 'key' + chr(92)  # 'key\'
+
+    # tokenize must not raise IndexError
+    tokens = list(tokenize(trailing_bs))
+    assert tokens  # produced at least one token
+
+    # parse must also be safe
+    paths = list(parse(trailing_bs))
+    assert paths

From e16491a1e45e469016d7a5ba72b5864292c5cc90 Mon Sep 17 00:00:00 2001
From: JSap0914 <JSap0914@users.noreply.github.com>
Date: Wed, 17 Jun 2026 15:53:25 +0900
Subject: [PATCH 2/2] style: add missing blank line before test function (E302)

---
 tests/test_json.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/test_json.py b/tests/test_json.py
index d946794314..4467ba723c 100644
--- a/tests/test_json.py
+++ b/tests/test_json.py
@@ -582,6 +582,7 @@ def test_nested_json_sparse_array(httpbin_both):
     r = http(httpbin_both + '/post', 'test[0]:=1', 'test[100]:=1')
     assert len(r.json['json']['test']) == 101
 
+
 def test_nested_json_trailing_backslash_no_crash():
     """A backslash at the very end of a key must not crash with IndexError.