From a1d04fc7513fe59acba24aa4da53ac7be93c1bbf Mon Sep 17 00:00:00 2001
From: SapirBaruch <sapirbaruch01@gmail.com>
Date: Tue, 2 Jun 2026 10:30:14 +0300
Subject: [PATCH 1/2] Fix indent filter ignoring blank=False for empty first
 line

When first=True is set, the indent filter was unconditionally prepending
the indentation to the whole string, even when blank=False and the first
line was empty. Now the first-line indentation is skipped when blank=False
and the first line has no content.

Fixes #2176
---
 CHANGES.rst           |  2 ++
 src/jinja2/filters.py |  2 +-
 tests/test_filters.py | 15 ++++++++++++++-
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/CHANGES.rst b/CHANGES.rst
index 338dc9966..9565c8d28 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -13,6 +13,8 @@ Unreleased
 -   Use modern packaging metadata with ``pyproject.toml`` instead of ``setup.cfg``.
     :pr:`1793`
 -   Use ``flit_core`` instead of ``setuptools`` as build backend.
+-   Fix ``indent`` filter not respecting ``blank=False`` for the first line
+    when ``first=True`` is set. :issue:`2176`
 
 
 Version 3.1.6
diff --git a/src/jinja2/filters.py b/src/jinja2/filters.py
index c46e20c10..897cfb331 100644
--- a/src/jinja2/filters.py
+++ b/src/jinja2/filters.py
@@ -860,7 +860,7 @@ def do_indent(
                 indention + line if line else line for line in lines
             )
 
-    if first:
+    if first and (blank or rv.split("\n", 1)[0]):
         rv = indention + rv
 
     return rv
diff --git a/tests/test_filters.py b/tests/test_filters.py
index 4601469a6..f80967b5a 100644
--- a/tests/test_filters.py
+++ b/tests/test_filters.py
@@ -166,7 +166,7 @@ def _test_indent_multiline_template(env, markup=False):
         t = env.from_string("{{ foo|indent(2, false, true) }}")
         assert t.render(foo=text) == '\n  foo bar\n  "baz"\n  '
         t = env.from_string("{{ foo|indent(2, true, false) }}")
-        assert t.render(foo=text) == '  \n  foo bar\n  "baz"\n'
+        assert t.render(foo=text) == '\n  foo bar\n  "baz"\n'
         t = env.from_string("{{ foo|indent(2, true, true) }}")
         assert t.render(foo=text) == '  \n  foo bar\n  "baz"\n  '
 
@@ -179,6 +179,19 @@ def test_indent(self, env):
         t = env.from_string('{{ "jinja"|indent(blank=true) }}')
         assert t.render() == "jinja"
 
+    def test_indent_first_blank(self, env):
+        # ``blank=False`` (the default) must suppress indentation of the first
+        # line when it is empty, even when ``first=True``.  Regression for
+        # https://github.com/pallets/jinja/issues/2176
+        t = env.from_string("{% filter indent(4, first=true) %}{% endfilter %}")
+        assert t.render() == ""
+        # A leading blank line is not indented when blank=False.
+        t = env.from_string('{{ "\nhello"|indent(4, first=true) }}')
+        assert t.render() == "\n    hello"
+        # blank=True still indents the first line even when it is empty.
+        t = env.from_string("{% filter indent(4, first=true, blank=true) %}{% endfilter %}")
+        assert t.render() == "    "
+
     def test_indent_markup_input(self, env):
         """
         Tests cases where the filter input is a Markup type

From bf7b0e8ba77d74790cc287db4992d8303e68ad6f Mon Sep 17 00:00:00 2001
From: "pre-commit-ci-lite[bot]"
 <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>
Date: Tue, 2 Jun 2026 07:31:46 +0000
Subject: [PATCH 2/2] [pre-commit.ci lite] apply automatic fixes

---
 tests/test_filters.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tests/test_filters.py b/tests/test_filters.py
index f80967b5a..58d85a811 100644
--- a/tests/test_filters.py
+++ b/tests/test_filters.py
@@ -189,7 +189,9 @@ def test_indent_first_blank(self, env):
         t = env.from_string('{{ "\nhello"|indent(4, first=true) }}')
         assert t.render() == "\n    hello"
         # blank=True still indents the first line even when it is empty.
-        t = env.from_string("{% filter indent(4, first=true, blank=true) %}{% endfilter %}")
+        t = env.from_string(
+            "{% filter indent(4, first=true, blank=true) %}{% endfilter %}"
+        )
         assert t.render() == "    "
 
     def test_indent_markup_input(self, env):