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- Remove outdated dependencies and update dependency versions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

diff/raw.rs

@@ -2,6 +2,8 @@ use crate::bare::GitBare;
 use crate::error::GitResult;
 use crate::pb::*;
 
+const MAX_RAW_DIFF_OUTPUT_BYTES: usize = 64 * 1024 * 1024;
+
 impl GitBare {
     /// Stream raw diff output.
     pub fn raw_diff(&self, request: RawDiffRequest) -> GitResult<Vec<RawDiffResponse>> {
@@ -16,6 +18,7 @@ impl GitBare {
             "diff".to_string(),
         ];
 
+        let mut pathspecs = Vec::new();
         // Apply options if present
         if let Some(ref opts) = request.options {
             if opts.recursive {
@@ -26,14 +29,18 @@ impl GitBare {
             } else {
                 args.push("--no-binary".to_string());
             }
-            for ps in &opts.pathspec {
-                args.push("--".to_string());
-                args.push(ps.clone());
+            for pathspec in &opts.pathspec {
+                crate::sanitize::validate_file_path(pathspec)?;
+                pathspecs.push(pathspec.clone());
             }
         }
 
         args.push(base.clone());
         args.push(head.clone());
+        if !pathspecs.is_empty() {
+            args.push("--".to_string());
+            args.extend(pathspecs);
+        }
 
         let output = std::process::Command::new("git")
             .args(&args)
@@ -44,6 +51,18 @@ 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(),
+            });
+        }
+
+        if output.stdout.len() > MAX_RAW_DIFF_OUTPUT_BYTES {
+            return Err(crate::error::GitError::InvalidArgument(format!(
+                "raw diff output too large (max {MAX_RAW_DIFF_OUTPUT_BYTES} bytes)"
+            )));
+        }
 
         // Chunk the output for streaming
         const CHUNK_SIZE: usize = 32768;
@@ -78,6 +97,18 @@ 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(),
+            });
+        }
+
+        if output.stdout.len() > MAX_RAW_DIFF_OUTPUT_BYTES {
+            return Err(crate::error::GitError::InvalidArgument(format!(
+                "raw patch output too large (max {MAX_RAW_DIFF_OUTPUT_BYTES} bytes)"
+            )));
+        }
 
         const CHUNK_SIZE: usize = 32768;
         let data = output.stdout;