refactor(cache): redesign cache system with structured keys and improved performance

- Add repo_path parameter to cached_response and cached_vec_response functions
- Implement structured cache key format with namespace, repo_path, and request proto
- Replace global cache with Moka in-memory cache using weight-based eviction
- Set 256MB memory cap with 10-minute TTL and 2-minute TTI policy
- Add metrics collection for cache operations and evictions
- Implement efficient repo-scoped invalidation using key structure
- Add detailed documentation comments explaining cache architecture
- Remove outdated dependencies and update dependency versions
- Add error handling for encoding failures in cache operations
- Optimize Vec responses with length-delimited encoding and pre-allocation

commit/query.rs

@@ -20,12 +20,13 @@ impl GitBare {
         } else {
             request.limit.min(200)
         };
+        let max_count = request.offset.saturating_add(limit).min(10_000);
 
         let mut args = vec![
             "--git-dir".to_string(),
             self.bare_dir.to_string_lossy().into_owned(),
             "log".to_string(),
-            format!("--max-count={}", limit),
+            format!("--max-count={max_count}"),
             "--format=%H".to_string(),
         ];
 
@@ -51,6 +52,12 @@ impl GitBare {
                 status_code: None,
                 stderr: e.to_string(),
             })?;
+        if !output.status.success() {
+            return Err(crate::error::GitError::CommandFailed {
+                status_code: output.status.code(),
+                stderr: String::from_utf8_lossy(&output.stderr).trim().to_string(),
+            });
+        }
 
         let stdout = String::from_utf8_lossy(&output.stdout);
         let repo = self.gix_repo()?;
@@ -94,7 +101,10 @@ impl GitBare {
     /// Get stats for a single commit.
     pub fn get_commit_stats(&self, request: GetCommitStatsRequest) -> GitResult<CommitStats> {
         let revision = match request.revision.and_then(|s| s.selector) {
-            Some(object_selector::Selector::Oid(oid)) => oid.hex,
+            Some(object_selector::Selector::Oid(oid)) => {
+                crate::sanitize::validate_oid_hex(&oid.hex)?;
+                oid.hex
+            }
             Some(object_selector::Selector::Revision(name)) => name.revision,
             None => "HEAD".to_string(),
         };
@@ -109,12 +119,18 @@ impl GitBare {
                 &format!("{revision}^!"),
             ])
             .stdout(std::process::Stdio::piped())
-            .stderr(std::process::Stdio::null())
+            .stderr(std::process::Stdio::piped())
             .output()
             .map_err(|e| crate::error::GitError::CommandFailed {
                 status_code: None,
                 stderr: e.to_string(),
             })?;
+        if !output.status.success() {
+            return Err(crate::error::GitError::CommandFailed {
+                status_code: output.status.code(),
+                stderr: String::from_utf8_lossy(&output.stderr).trim().to_string(),
+            });
+        }
 
         let stdout = String::from_utf8_lossy(&output.stdout);
         let mut additions = 0u32;
@@ -125,12 +141,12 @@ impl GitBare {
             let parts: Vec<&str> = line.split('\t').collect();
             if parts.len() >= 2 {
                 if let Ok(add) = parts[0].parse::<u32>() {
-                    additions += add;
+                    additions = additions.saturating_add(add);
                 }
                 if let Ok(del) = parts[1].parse::<u32>() {
-                    deletions += del;
+                    deletions = deletions.saturating_add(del);
                 }
-                changed_files += 1;
+                changed_files = changed_files.saturating_add(1);
             }
         }
 
@@ -170,12 +186,18 @@ impl GitBare {
         let output = std::process::Command::new("git")
             .args(&args)
             .stdout(std::process::Stdio::piped())
-            .stderr(std::process::Stdio::null())
+            .stderr(std::process::Stdio::piped())
             .output()
             .map_err(|e| crate::error::GitError::CommandFailed {
                 status_code: None,
                 stderr: e.to_string(),
             })?;
+        if !output.status.success() {
+            return Err(crate::error::GitError::CommandFailed {
+                status_code: output.status.code(),
+                stderr: String::from_utf8_lossy(&output.stderr).trim().to_string(),
+            });
+        }
 
         let stdout = String::from_utf8_lossy(&output.stdout);
         let hex = stdout.lines().next().unwrap_or("").trim().to_string();