docs: env var doc improvements (#8777)

## Summary

* Env docs now support anchors, which allows sending a link to someone
with a direct reference to an env var or cross-reference them in the
docs.
* Marked additional env vars as hidden from the docs due to their
internal use
* Updates some tests still using literals to use the static env vars

## Test Plan

<img width="1370" alt="env_var_anchors"
src="https://github.com/user-attachments/assets/52ae1caa-5199-4798-9eb5-81b8f5b57c24">

crates/uv-dev/src/generate_env_vars_reference.rs

@@ -88,7 +88,9 @@ fn generate() -> String {
             })
             .collect::<Vec<_>>()
             .join("\n");
-        output.push_str(&format!("- `{var}`: {doc}\n"));
+        output.push_str(&format!(
+            "- <a id=\"{var}\"></a> [`{var}`](#{var}): {doc}\n"
+        ));
     }
 
     output

crates/uv-static/src/env_vars.rs

@@ -185,6 +185,9 @@ impl EnvVars {
     /// packages.
     pub const UV_CONCURRENT_INSTALLS: &'static str = "UV_CONCURRENT_INSTALLS";
 
+    /// Disables all progress output. For example, spinners and progress bars.
+    pub const UV_NO_PROGRESS: &'static str = "UV_NO_PROGRESS";
+
     /// Specifies the directory where uv stores managed tools.
     pub const UV_TOOL_DIR: &'static str = "UV_TOOL_DIR";
 
@@ -370,9 +373,6 @@ impl EnvVars {
     /// See [no-color.org](https://no-color.org).
     pub const NO_COLOR: &'static str = "NO_COLOR";
 
-    /// Disables all progress output. For example, spinners and progress bars.
-    pub const UV_NO_PROGRESS: &'static str = "UV_NO_PROGRESS";
-
     /// Forces colored output regardless of terminal support.
     ///
     /// See [force-color.org](https://force-color.org).
@@ -397,18 +397,23 @@ impl EnvVars {
     pub const LOCALAPPDATA: &'static str = "LOCALAPPDATA";
 
     /// Path to the `.git` directory. Ignored by `uv` when performing fetch.
+    #[attr_hidden]
     pub const GIT_DIR: &'static str = "GIT_DIR";
 
     /// Path to the git working tree. Ignored by `uv` when performing fetch.
+    #[attr_hidden]
     pub const GIT_WORK_TREE: &'static str = "GIT_WORK_TREE";
 
     /// Path to the index file for staged changes. Ignored by `uv` when performing fetch.
+    #[attr_hidden]
     pub const GIT_INDEX_FILE: &'static str = "GIT_INDEX_FILE";
 
     /// Path to where git object files are located. Ignored by `uv` when performing fetch.
+    #[attr_hidden]
     pub const GIT_OBJECT_DIRECTORY: &'static str = "GIT_OBJECT_DIRECTORY";
 
     /// Alternate locations for git objects. Ignored by `uv` when performing fetch.
+    #[attr_hidden]
     pub const GIT_ALTERNATE_OBJECT_DIRECTORIES: &'static str = "GIT_ALTERNATE_OBJECT_DIRECTORIES";
 
     /// Used in tests for better git isolation.
@@ -419,6 +424,7 @@ impl EnvVars {
     /// `GIT_CEILING_DIRECTORIES=/home/andrew/.local/share/uv/tests` will
     /// prevent git from crawling up the directory tree past that point to find
     /// parent git repositories.
+    #[attr_hidden]
     pub const GIT_CEILING_DIRECTORIES: &'static str = "GIT_CEILING_DIRECTORIES";
 
     /// Used for trusted publishing via `uv publish`.
@@ -431,18 +437,26 @@ impl EnvVars {
     pub const ACTIONS_ID_TOKEN_REQUEST_TOKEN: &'static str = "ACTIONS_ID_TOKEN_REQUEST_TOKEN";
 
     /// Sets the encoding for standard I/O streams (e.g., PYTHONIOENCODING=utf-8).
+    #[attr_hidden]
     pub const PYTHONIOENCODING: &'static str = "PYTHONIOENCODING";
 
     /// Forces unbuffered I/O streams, equivalent to `-u` in Python.
+    #[attr_hidden]
     pub const PYTHONUNBUFFERED: &'static str = "PYTHONUNBUFFERED";
 
     /// Enables UTF-8 mode for Python, equivalent to `-X utf8`.
+    #[attr_hidden]
     pub const PYTHONUTF8: &'static str = "PYTHONUTF8";
 
     /// Adds directories to Python module search path (e.g., PYTHONPATH=/path/to/modules).
     pub const PYTHONPATH: &'static str = "PYTHONPATH";
 
+    /// Used in tests to enforce a consistent locale setting.
+    #[attr_hidden]
+    pub const LC_ALL: &'static str = "LC_ALL";
+
     /// Typically set by CI runners, used to detect a CI runner.
+    #[attr_hidden]
     pub const CI: &'static str = "CI";
 
     /// Use to set the .netrc file location.
@@ -455,6 +469,7 @@ impl EnvVars {
     pub const JPY_SESSION_NAME: &'static str = "JPY_SESSION_NAME";
 
     /// Use to create the tracing root directory via the `tracing-durations-export` feature.
+    #[attr_hidden]
     pub const TRACING_DURATIONS_TEST_ROOT: &'static str = "TRACING_DURATIONS_TEST_ROOT";
 
     /// Use to create the tracing durations file via the `tracing-durations-export` feature.

crates/uv/tests/it/common/mod.rs

@@ -478,7 +478,7 @@ impl TestContext {
 
         if cfg!(unix) {
             // Avoid locale issues in tests
-            command.env("LC_ALL", "C");
+            command.env(EnvVars::LC_ALL, "C");
         }
 
         if cfg!(all(windows, debug_assertions)) {
@@ -663,10 +663,9 @@ impl TestContext {
             .env(EnvVars::UV_PYTHON_BIN_DIR, bin.as_os_str())
             .env(
                 EnvVars::PATH,
-                std::env::join_paths(
-                    std::iter::once(bin)
-                        .chain(std::env::split_paths(&env::var("PATH").unwrap_or_default())),
-                )
+                std::env::join_paths(std::iter::once(bin).chain(std::env::split_paths(
+                    &env::var(EnvVars::PATH).unwrap_or_default(),
+                )))
                 .unwrap(),
             )
             .current_dir(&self.temp_dir);

crates/uv/tests/it/edit.rs

@@ -6819,7 +6819,7 @@ fn add_index_credentials() -> Result<()> {
     "#})?;
 
     // Provide credentials for the index via the environment variable.
-    uv_snapshot!(context.filters(), context.add().arg("iniconfig==2.0.0").env("UV_DEFAULT_INDEX", "https://public:heron@pypi-proxy.fly.dev/basic-auth/simple"), @r###"
+    uv_snapshot!(context.filters(), context.add().arg("iniconfig==2.0.0").env(EnvVars::UV_DEFAULT_INDEX, "https://public:heron@pypi-proxy.fly.dev/basic-auth/simple"), @r###"
     success: true
     exit_code: 0
     ----- stdout -----
@@ -6913,7 +6913,7 @@ fn add_index_comments() -> Result<()> {
     "#})?;
 
     // Preserve the comment on the index URL, despite replacing it.
-    uv_snapshot!(context.filters(), context.add().arg("iniconfig==2.0.0").env("UV_DEFAULT_INDEX", "https://pypi.org/simple"), @r###"
+    uv_snapshot!(context.filters(), context.add().arg("iniconfig==2.0.0").env(EnvVars::UV_DEFAULT_INDEX, "https://pypi.org/simple"), @r###"
     success: true
     exit_code: 0
     ----- stdout -----

crates/uv/tests/it/init.rs

@@ -2416,7 +2416,7 @@ fn init_application_package_flit() -> Result<()> {
         );
     });
 
-    uv_snapshot!(context.filters(), context.run().current_dir(&child).env_remove("VIRTUAL_ENV").arg("foo"), @r###"
+    uv_snapshot!(context.filters(), context.run().current_dir(&child).env_remove(EnvVars::VIRTUAL_ENV).arg("foo"), @r###"
     success: true
     exit_code: 0
     ----- stdout -----
@@ -2497,7 +2497,7 @@ fn init_library_flit() -> Result<()> {
         );
     });
 
-    uv_snapshot!(context.filters(), context.run().current_dir(&child).env_remove("VIRTUAL_ENV").arg("python").arg("-c").arg("import foo; print(foo.hello())"), @r###"
+    uv_snapshot!(context.filters(), context.run().current_dir(&child).env_remove(EnvVars::VIRTUAL_ENV).arg("python").arg("-c").arg("import foo; print(foo.hello())"), @r###"
     success: true
     exit_code: 0
     ----- stdout -----

crates/uv/tests/it/lock.rs

@@ -13435,7 +13435,7 @@ fn lock_named_index_cli() -> Result<()> {
     )?;
 
     // The package references a non-existent index.
-    uv_snapshot!(context.filters(), context.lock().env_remove("UV_EXCLUDE_NEWER"), @r###"
+    uv_snapshot!(context.filters(), context.lock().env_remove(EnvVars::UV_EXCLUDE_NEWER), @r###"
     success: false
     exit_code: 2
     ----- stdout -----
@@ -13447,7 +13447,7 @@ fn lock_named_index_cli() -> Result<()> {
     "###);
 
     // But it's fine if it comes from the CLI.
-    uv_snapshot!(context.filters(), context.lock().arg("--index").arg("pytorch=https://download.pytorch.org/whl/cu121").env_remove("UV_EXCLUDE_NEWER"), @r###"
+    uv_snapshot!(context.filters(), context.lock().arg("--index").arg("pytorch=https://download.pytorch.org/whl/cu121").env_remove(EnvVars::UV_EXCLUDE_NEWER), @r###"
     success: true
     exit_code: 0
     ----- stdout -----

crates/uv/tests/it/pip_compile.rs

@@ -5508,7 +5508,7 @@ fn emit_index_urls() -> Result<()> {
             .arg("https://test.pypi.org/simple/")
             .arg("--extra-index-url")
             .arg("https://pypi.org/simple")
-            .env("UV_EXTRA_INDEX_URL", "https://pypi.org/simple"), @r###"
+            .env(EnvVars::UV_EXTRA_INDEX_URL, "https://pypi.org/simple"), @r###"
     success: true
     exit_code: 0
     ----- stdout -----