feat(vcs): add mozart-vcs crate for VCS repository support

Implement VCS driver/downloader infrastructure mirroring Composer's VCS
subsystem. Includes drivers for GitHub, GitLab, Bitbucket, Forgejo, Git,
Hg, and SVN with API-based metadata resolution, plus source downloaders
for Git/Hg/SVN. Integrates into mozart-registry via vcs_bridge module to
scan VCS repositories and feed discovered packages into the SAT resolver.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

1 files changed, 91 insertions, 0 deletions

diff --git a/crates/mozart-vcs/src/util/svn.rs b/crates/mozart-vcs/src/util/svn.rs
new file mode 100644
index 0000000..e9a6813
--- /dev/null
+++ b/crates/mozart-vcs/src/util/svn.rs
@@ -0,0 +1,91 @@
+use std::path::Path;
+
+use anyhow::Result;
+
+use crate::process::{ProcessExecutor, ProcessOutput};
+
+/// SVN credentials for authenticated operations.
+#[derive(Debug, Clone)]
+pub struct SvnCredentials {
+    pub username: String,
+    pub password: String,
+}
+
+/// SVN utility for command execution with credential handling.
+pub struct SvnUtil {
+    process: ProcessExecutor,
+}
+
+impl SvnUtil {
+    pub fn new(process: ProcessExecutor) -> Self {
+        Self { process }
+    }
+
+    /// Execute an SVN command with `--non-interactive`.
+    pub fn execute(&self, args: &[&str], cwd: Option<&Path>) -> Result<ProcessOutput> {
+        let mut full_args = vec!["svn"];
+        full_args.extend_from_slice(args);
+        full_args.push("--non-interactive");
+        self.process.execute_checked(&full_args, cwd)
+    }
+
+    /// Execute an SVN command with optional credentials, retrying on auth failure.
+    pub fn execute_with_credentials(
+        &self,
+        args: &[&str],
+        creds: Option<&SvnCredentials>,
+        cwd: Option<&Path>,
+    ) -> Result<ProcessOutput> {
+        let mut full_args = vec!["svn"];
+        full_args.extend_from_slice(args);
+        full_args.push("--non-interactive");
+
+        let cred_args: Vec<String>;
+        if let Some(c) = creds {
+            cred_args = vec![
+                "--username".to_string(),
+                c.username.clone(),
+                "--password".to_string(),
+                c.password.clone(),
+            ];
+            for arg in &cred_args {
+                full_args.push(arg);
+            }
+        }
+
+        let full_args_refs: Vec<&str> = full_args.iter().map(|s| &**s).collect();
+
+        // Retry up to 5 times on auth failure
+        let max_retries = 5;
+        let mut last_output = None;
+        for _ in 0..max_retries {
+            let output = self.process.execute(&full_args_refs, cwd)?;
+            if output.status == 0 {
+                return Ok(output);
+            }
+            // Check if it's an auth error (SVN exit code or stderr hint)
+            if !output.stderr.contains("authorization failed")
+                && !output.stderr.contains("Could not authenticate")
+                && !output.stderr.contains("Authentication failed")
+            {
+                // Not an auth error, return immediately
+                last_output = Some(output);
+                break;
+            }
+            last_output = Some(output);
+        }
+
+        match last_output {
+            Some(output) if output.status != 0 => {
+                anyhow::bail!(
+                    "SVN command `{}` failed with exit code {}\nstderr: {}",
+                    full_args_refs.join(" "),
+                    output.status,
+                    output.stderr.trim(),
+                );
+            }
+            Some(output) => Ok(output),
+            None => anyhow::bail!("SVN command failed with no output"),
+        }
+    }
+}