From e84d7436b134c433efc9ea35082606cf7ad7dd30 Mon Sep 17 00:00:00 2001
From: Sanjay Santhanam <51058514+Sanjays2402@users.noreply.github.com>
Date: Fri, 24 Jul 2026 22:32:27 -0700
Subject: [PATCH] Make pip-sync honor src_files from the config file

pip-compile reads src_files out of the click context default_map when
none are given on the command line, but pip-sync never did, so
[tool.pip-tools.sync] src_files was silently ignored and pip-sync always
fell back to requirements.txt (or exited 2 when it was absent).

Apply the same default_map lookup in pip-sync. CLI arguments still win.

Fixes #2187
---
 changelog.d/2187.bugfix.md |  1 +
 piptools/scripts/sync.py   |  8 ++++++++
 tests/test_cli_sync.py     | 40 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 49 insertions(+)
 create mode 100644 changelog.d/2187.bugfix.md

diff --git a/changelog.d/2187.bugfix.md b/changelog.d/2187.bugfix.md
new file mode 100644
index 000000000..5abcc099f
--- /dev/null
+++ b/changelog.d/2187.bugfix.md
@@ -0,0 +1 @@
+Made `pip-sync` respect `src_files` set in the config file, matching `pip-compile` -- by {user}`Sanjays2402`.
diff --git a/piptools/scripts/sync.py b/piptools/scripts/sync.py
index 877d58a05..3525ce809 100755
--- a/piptools/scripts/sync.py
+++ b/piptools/scripts/sync.py
@@ -48,6 +48,7 @@
 
 
 @click.command(name="pip-sync")
+@click.pass_context
 @options.help_option(epilog=SYNC_EPILOG)
 @options.version
 @options.ask
@@ -69,6 +70,7 @@
 @options.config
 @options.no_config
 def cli(
+    ctx: click.Context,
     ask: bool,
     dry_run: bool,
     force: bool,
@@ -91,6 +93,12 @@ def cli(
     """Synchronize virtual environment with requirements.txt."""
     log.verbosity = verbose - quiet
 
+    # If ``src_files`` was not provided as an input, but rather as config,
+    # it will be part of the click context ``ctx``.
+    # However, if ``src_files`` is specified, then we want to use that.
+    if not src_files and ctx.default_map and "src_files" in ctx.default_map:
+        src_files = tuple(ctx.default_map["src_files"])
+
     if not src_files:
         if os.path.exists(DEFAULT_REQUIREMENTS_FILE):
             src_files = (DEFAULT_REQUIREMENTS_FILE,)
diff --git a/tests/test_cli_sync.py b/tests/test_cli_sync.py
index a07f97309..b1cf8d6c9 100644
--- a/tests/test_cli_sync.py
+++ b/tests/test_cli_sync.py
@@ -488,3 +488,43 @@ def test_tool_specific_config_option(run, runner, make_config_file):
 
     assert out.exit_code == 1
     assert "Would install:" in out.stdout
+
+
+@mock.patch("piptools.sync.run")
+def test_use_src_files_from_config_if_option_is_not_specified_from_cli(
+    run, runner, make_config_file
+):
+    config_file = make_config_file(
+        "src-files", ["requirements_lock.txt"], section="pip-tools", subsection="sync"
+    )
+
+    with open("requirements_lock.txt", "w") as reqs_txt:
+        reqs_txt.write("six==1.10.0")
+
+    out = runner.invoke(cli, ["--dry-run", "--config", config_file.as_posix()])
+
+    assert out.exit_code == 1
+    assert "Would install:" in out.stdout
+    assert "six==1.10.0" in out.stdout
+
+
+@mock.patch("piptools.sync.run")
+def test_use_src_files_from_cli_if_option_is_specified_in_both_config_and_cli(
+    run, runner, make_config_file
+):
+    config_file = make_config_file(
+        "src-files", ["requirements_lock.txt"], section="pip-tools", subsection="sync"
+    )
+
+    with open("requirements_lock.txt", "w") as reqs_txt:
+        reqs_txt.write("six==1.10.0")
+    with open("other.txt", "w") as reqs_txt:
+        reqs_txt.write("small-fake-a==0.1")
+
+    out = runner.invoke(
+        cli, ["other.txt", "--dry-run", "--config", config_file.as_posix()]
+    )
+
+    assert out.exit_code == 1
+    assert "small-fake-a==0.1" in out.stdout
+    assert "six==1.10.0" not in out.stdout