Stream workspace metadata JSON serialization

crates/uv-resolver/src/lock/export/metadata.rs

@@ -1492,7 +1492,7 @@ impl Metadata {
         self
     }
 
-    pub fn to_json(&self) -> Result<String, MetadataError> {
-        Ok(serde_json::to_string_pretty(self)?)
+    pub fn write_json(&self, writer: impl std::io::Write) -> Result<(), MetadataError> {
+        Ok(serde_json::to_writer_pretty(writer, self)?)
     }
 }

crates/uv/src/commands/workspace/metadata.rs

@@ -1,4 +1,4 @@
-use std::fmt::Write;
+use std::io::{BufWriter, Write};
 use std::path::Path;
 
 use anyhow::{Context, Result};
@@ -22,7 +22,7 @@ use crate::commands::project::{
     ScriptInterpreter, UniversalState, WorkspacePython,
 };
 use crate::commands::{ExitStatus, UvError, diagnostics};
-use crate::printer::Printer;
+use crate::printer::{Printer, Stdout};
 use crate::settings::{FrozenSource, LockCheck, ResolverSettings};
 
 use super::module_owners::collect_module_owners;
@@ -272,7 +272,12 @@ fn metadata_for_target(target: InstallTarget<'_>) -> Result<Metadata> {
 }
 
 fn print_metadata(export: &Metadata, printer: Printer) -> Result<ExitStatus> {
-    writeln!(printer.stdout(), "{}", export.to_json()?)?;
+    if printer.stdout() == Stdout::Enabled {
+        let mut stdout = BufWriter::new(anstream::stdout().lock());
+        export.write_json(&mut stdout)?;
+        writeln!(stdout)?;
+        stdout.flush()?;
+    }
 
     Ok(ExitStatus::Success)
 }

crates/uv/tests/workspace/workspace_metadata.rs

@@ -129,6 +129,30 @@ fn workspace_metadata_simple() {
     assert!(!workspace.child(".venv").exists());
 }
 
+#[test]
+fn workspace_metadata_quiet() {
+    let context = uv_test::test_context!("3.12");
+    context.init().arg("foo").assert().success();
+
+    let workspace = context.temp_dir.child("foo");
+
+    uv_snapshot!(context.filters(), context.workspace_metadata().current_dir(&workspace).arg("--quiet"), @r"
+    exit_code: 0 (success)
+    ");
+}
+
+#[test]
+fn workspace_metadata_extra_quiet() {
+    let context = uv_test::test_context!("3.12");
+    context.init().arg("foo").assert().success();
+
+    let workspace = context.temp_dir.child("foo");
+
+    uv_snapshot!(context.filters(), context.workspace_metadata().current_dir(&workspace).arg("--quiet").arg("--quiet"), @r"
+    exit_code: 0 (success)
+    ");
+}
+
 #[test]
 fn workspace_metadata_ignores_unusable_environment() -> Result<()> {
     let context = uv_test::test_context!("3.12");