feat(server): add tracing spans and caching to archive and blame services

- Add tracing spans with repo labels for archive and blame operations
- Implement caching for archive list entries when using OID selectors
- Implement caching for blame operations when using OID selectors
- Add detailed

bare.rs

@@ -3,14 +3,24 @@ use std::path::{Path, PathBuf};
 use crate::error::{GitError, GitResult};
 use crate::pb::RepositoryHeader;
 
+#[derive(Debug)]
 pub struct GitBare {
     pub bare_dir: PathBuf,
 }
 
 impl GitBare {
+    pub fn new(bare_dir: PathBuf) -> Self {
+        Self { bare_dir }
+    }
+
+    /// Open the gix repository. Callers should open once per logical operation
+    /// and reuse the handle for all gix lookups within that operation.
     pub fn gix_repo(&self) -> GitResult<gix::Repository> {
-        gix::open(&self.bare_dir)
-            .map_err(|e| GitError::Internal(format!("failed to open gix repository: {e}")))
+        tracing::debug!(repo = %self.bare_dir.display(), "opening gix repository");
+        gix::open(&self.bare_dir).map_err(|e| {
+            tracing::error!(repo = %self.bare_dir.display(), error = %e, "failed to open gix repository");
+            GitError::Internal(format!("failed to open gix repository: {e}"))
+        })
     }
 
     pub fn from_repository_header(header: &RepositoryHeader) -> GitResult<Self> {
@@ -47,6 +57,11 @@ impl GitBare {
             // Path traversal check: canonical resolved dir must start with base
             let base_canon = base.canonicalize().unwrap_or_else(|_| base.clone());
             if !canonical.starts_with(&base_canon) {
+                tracing::warn!(
+                    relative_path = %relative_path,
+                    base = %base_canon.display(),
+                    "path traversal attempt detected"
+                );
                 return Err(GitError::InvalidArgument(format!(
                     "path traversal detected: {relative_path} escapes storage root"
                 )));
@@ -60,6 +75,7 @@ impl GitBare {
 
         // Validate bare_dir exists, is a directory, and is readable
         if !bare_dir.exists() {
+            tracing::warn!(path = %bare_dir.display(), "repository not found");
             return Err(GitError::RepoNotFound);
         }
         if !bare_dir.is_dir() {
@@ -75,6 +91,7 @@ impl GitBare {
             // Maybe it's a non-bare repo
             let git_dir = bare_dir.join(".git");
             if git_dir.is_dir() && git_dir.join("HEAD").exists() {
+                tracing::debug!(path = %git_dir.display(), "resolved non-bare repo via .git subdir");
                 return Ok(Self { bare_dir: git_dir });
             }
             return Err(GitError::NotBareRepository);
@@ -87,6 +104,7 @@ impl GitBare {
     pub fn object_format(&self) -> crate::pb::ObjectFormat {
         let repo = self.gix_repo().ok();
         let kind = repo
+            .as_ref()
             .map(|r| r.object_hash())
             .unwrap_or(gix::hash::Kind::Sha1);
         match kind {