ux: add python as a minor pinning as its to important for beginner us…

…ers to not get wrong

src/cli/add.rs

@@ -3,28 +3,28 @@ use std::{
     str::FromStr,
 };
 
+use super::has_specs::HasSpecs;
+use crate::environment::LockFileUsage;
+use crate::{
+    cli::cli_config::{DependencyConfig, PrefixUpdateConfig, ProjectConfig},
+    environment::verify_prefix_location_unchanged,
+    load_lock_file,
+    lock_file::{filter_lock_file, LockFileDerivedData, UpdateContext},
+    project::{grouped_environment::GroupedEnvironment, DependencyType, Project},
+};
 use clap::Parser;
 use indexmap::IndexMap;
 use itertools::Itertools;
 use pep440_rs::VersionSpecifiers;
 use pep508_rs::{Requirement, VersionOrUrl::VersionSpecifier};
+use pixi_config::PinningStrategy;
 use pixi_manifest::{
     pypi::PyPiPackageName, DependencyOverwriteBehavior, FeatureName, FeaturesExt, HasFeaturesIter,
     SpecType,
 };
 use rattler_conda_types::{MatchSpec, PackageName, Platform, Version};
 use rattler_lock::{LockFile, Package};
 
-use super::has_specs::HasSpecs;
-use crate::environment::LockFileUsage;
-use crate::{
-    cli::cli_config::{DependencyConfig, PrefixUpdateConfig, ProjectConfig},
-    environment::verify_prefix_location_unchanged,
-    load_lock_file,
-    lock_file::{filter_lock_file, LockFileDerivedData, UpdateContext},
-    project::{grouped_environment::GroupedEnvironment, DependencyType, Project},
-};
-
 /// Adds dependencies to the project
 ///
 /// The dependencies should be defined as MatchSpec for conda package, or a PyPI
@@ -380,18 +380,25 @@ fn update_conda_specs_from_lock_file(
         .flatten()
         .collect_vec();
 
-    let pinning_strategy = project.config().pinning_strategy.unwrap_or_default();
+    let mut pinning_strategy = project.config().pinning_strategy;
     let channel_config = project.channel_config();
     for (name, (spec_type, spec)) in conda_specs_to_add_constraints_for {
-        let version_constraint = pinning_strategy.determine_version_constraint(
-            conda_records.iter().filter_map(|record| {
+        // Edge case: python is a special case where we want to pin the minor version by default.
+        // This is done to avoid early user confusion when the minor version changes and environments magically start breaking.
+        // This move a `>=3.13, <4` to a `>=3.13, <3.14` constraint.
+        if name.as_normalized() == "python" && pinning_strategy.is_none() {
+            pinning_strategy = Some(PinningStrategy::Minor);
+        }
+
+        let version_constraint = pinning_strategy
+            .unwrap_or_default()
+            .determine_version_constraint(conda_records.iter().filter_map(|record| {
                 if record.package_record.name == name {
                     Some(record.package_record.version.version())
                 } else {
                     None
                 }
-            }),
-        );
+            }));
 
         if let Some(version_constraint) = version_constraint {
             implicit_constraints

tests/add_tests.rs

@@ -515,3 +515,66 @@ async fn add_unconstrainted_dependency() {
     bar = "*"
     "###);
 }
+
+#[tokio::test]
+async fn pinning_dependency() {
+    // Create a channel with a single package
+    let mut package_database = PackageDatabase::default();
+    package_database.add_package(Package::build("foobar", "1").finish());
+    package_database.add_package(Package::build("python", "3.13").finish());
+
+    let local_channel = package_database.into_channel().await.unwrap();
+
+    // Initialize a new pixi project using the above channel
+    let pixi = PixiControl::new().unwrap();
+    pixi.init().with_channel(local_channel.url()).await.unwrap();
+
+    // Add the `packages` to the project
+    pixi.add("foobar").await.unwrap();
+    pixi.add("python").await.unwrap();
+
+    let project = pixi.project().unwrap();
+
+    // Get the specs for the `python` package
+    let python_spec = project
+        .manifest()
+        .default_feature()
+        .dependencies(None, None)
+        .unwrap_or_default()
+        .get("python")
+        .cloned()
+        .unwrap()
+        .to_toml_value()
+        .to_string();
+    // Testing to see if edge cases are handled correctly
+    // Python shouldn't be automatically pinned to a major version.
+    assert_eq!(python_spec, r#"">=3.13,<3.14""#);
+
+    // Get the specs for the `foobar` package
+    let foobar_spec = project
+        .manifest()
+        .default_feature()
+        .dependencies(None, None)
+        .unwrap_or_default()
+        .get("foobar")
+        .cloned()
+        .unwrap()
+        .to_toml_value()
+        .to_string();
+    assert_eq!(foobar_spec, r#"">=1,<2""#);
+
+    // Add the `python` package with a specific version
+    pixi.add("python==3.13").await.unwrap();
+    let project = pixi.project().unwrap();
+    let python_spec = project
+        .manifest()
+        .default_feature()
+        .dependencies(None, None)
+        .unwrap_or_default()
+        .get("python")
+        .cloned()
+        .unwrap()
+        .to_toml_value()
+        .to_string();
+    assert_eq!(python_spec, r#""==3.13""#);
+}