diff --git a/packages/playground/data-liberation/src/git/WP_Git_Cached_Index.php b/packages/playground/data-liberation/src/git/WP_Git_Cached_Index.php
index c62169a01a..7678c18652 100644
--- a/packages/playground/data-liberation/src/git/WP_Git_Cached_Index.php
+++ b/packages/playground/data-liberation/src/git/WP_Git_Cached_Index.php
@@ -8,8 +8,10 @@ class WP_Git_Cached_Index {
 
     private $oid;
     private $type;
-    private $length;
-    private $contents;
+    private $content_inflate_handle;
+    private $object_content_chunk;
+    private $called_next_object_chunk;
+    private $buffered_object_content;
     private $parsed_commit;
     private $parsed_tree;
     private $last_error;
@@ -31,33 +33,142 @@ public function __construct(
         }
     }
 
-    /**
-     * @TODO: Streaming read. Don't load everything into memory.
-     */
     public function read_object($oid) {
-        // Reset the object state
-        $this->oid = null;
-        $this->type = null;
-        $this->length = null;
-        $this->contents = null;
-        $this->parsed_commit = null;
-        $this->parsed_tree = null;
+        $this->reset();
+
+        $object_path = $this->get_object_path($oid);
+        if(!$this->fs->is_file($object_path)) {
+            return false;
+        }
 
-        $contents = $this->fs->read_file($this->get_object_path($oid));
-        $contents = WP_Git_Pack_Processor::inflate($contents);
-        $type_length = strpos($contents, ' ');
         $this->oid = $oid;
-        $this->type = substr($contents, 0, $type_length);
-        $this->length = substr($contents, $type_length + 1, strpos($contents, "\x00", $type_length) - $type_length - 1);
-        $this->contents = substr($contents, strpos($contents, "\x00", $type_length) + 1);
-        if($this->type === WP_Git_Pack_Processor::OBJECT_NAMES[WP_Git_Pack_Processor::OBJECT_TYPE_COMMIT]) {
-            $this->parsed_commit = WP_Git_Pack_Processor::parse_commit_message($this->contents);
-        } else if($this->type === WP_Git_Pack_Processor::OBJECT_NAMES[WP_Git_Pack_Processor::OBJECT_TYPE_TREE]) {
-            $this->parsed_tree = WP_Git_Pack_Processor::parse_tree_bytes($this->contents);
+        if(!$this->open_object_stream()) {
+            return false;
+        }
+
+        // Read the object header and initialize the internal state
+        // for the specific get_* methods below.
+        $header = false;
+        $content = '';
+        while($this->next_object_chunk()) {
+            $content .= $this->get_object_content_chunk();
+            $null_byte_position = strpos($content, "\x00");
+            if($null_byte_position === false) {
+                continue;
+            }
+            $header = substr($content, 0, $null_byte_position);
+            break;
+        }
+
+        if(false === $header) {
+            $this->last_error = 'Failed to read the object header';
+            return false;
+        }
+
+        $this->object_content_chunk = substr($content, strlen($header) + 1);
+
+        // Parse the header
+        $type_length = strpos($header, ' ');
+        $type = substr($header, 0, $type_length);
+        switch($type) {
+            case WP_Git_Pack_Processor::OBJECT_NAMES[WP_Git_Pack_Processor::OBJECT_TYPE_BLOB]:
+                $this->type = WP_Git_Pack_Processor::OBJECT_TYPE_BLOB;
+                break;
+            case WP_Git_Pack_Processor::OBJECT_NAMES[WP_Git_Pack_Processor::OBJECT_TYPE_TREE]:
+                $this->type = WP_Git_Pack_Processor::OBJECT_TYPE_TREE;
+                break;
+            case WP_Git_Pack_Processor::OBJECT_NAMES[WP_Git_Pack_Processor::OBJECT_TYPE_COMMIT]:
+                $this->type = WP_Git_Pack_Processor::OBJECT_TYPE_COMMIT;
+                break;
+            default:
+                $this->last_error = 'Invalid object type: ' . $type;
+                return false;
         }
         return true;
     }
 
+    public function get_type() {
+        return $this->type;
+    }
+
+    public function get_length() {
+        return $this->fs->get_streamed_file_length();
+    }
+
+    private function open_object_stream() {
+        $this->content_inflate_handle = inflate_init(ZLIB_ENCODING_DEFLATE);
+        if(!$this->content_inflate_handle) {
+            $this->last_error = 'Failed to initialize inflate handle';
+            return false;
+        }
+        if(!$this->fs->open_file_stream($this->get_object_path($this->oid))) {
+            return false;
+        }
+        return true;
+    }
+
+    public function next_object_chunk() {
+        if(false === $this->fs->next_file_chunk()) {
+            $this->last_error = $this->fs->get_error_message();
+            return false;
+        }
+        $this->called_next_object_chunk = true;
+        $chunk = $this->fs->get_file_chunk();
+        $next_chunk = inflate_add($this->content_inflate_handle, $chunk);
+        if(false === $next_chunk) {
+            $this->last_error = 'Failed to inflate chunk';
+            $this->close_object_stream();
+            return false;
+        }
+        $this->object_content_chunk = $next_chunk;
+        return true;
+    }
+
+    public function get_object_content_chunk() {
+        return $this->object_content_chunk;
+    }
+
+    private function close_object_stream() {
+        $this->fs->close_file_stream();
+        $this->content_inflate_handle = null;
+        return true;
+    }
+
+    public function get_parsed_commit() {
+        if(null === $this->parsed_commit) {
+            $commit_contents = $this->read_entire_object_contents();
+            $this->parsed_commit = WP_Git_Pack_Processor::parse_commit_message($commit_contents);
+        }
+        return $this->parsed_commit;
+    }
+
+    public function get_parsed_tree() {
+        if(null === $this->parsed_tree) {
+            $tree_contents = $this->read_entire_object_contents();
+            $this->parsed_tree = WP_Git_Pack_Processor::parse_tree_bytes($tree_contents);
+        }
+        return $this->parsed_tree;
+    }
+
+    public function read_entire_object_contents() {
+        // If we've advanced the stream, we can't reuse it to read the entire
+        // object anymore. Let's re-initialize the stream.
+        if($this->called_next_object_chunk) {
+            $this->read_object($this->oid);
+        }
+        if(null !== $this->buffered_object_content) {
+            return $this->buffered_object_content;
+        }
+        // Load the entire object into memory and keep the result
+        // for later use. We'll likely need it again before we're
+        // done with the current object.
+        $this->buffered_object_content = $this->object_content_chunk;
+        while($this->next_object_chunk()) {
+            $this->buffered_object_content .= $this->get_object_content_chunk();
+        }
+        return $this->buffered_object_content;
+    }
+
     public function oid_exists($oid) {
         return $this->fs->is_file($this->get_object_path($oid));
     }
@@ -68,7 +179,10 @@ public function read_by_path($path, $root_tree_oid=null) {
             if(false === $this->read_object($head_oid)) {
                 return false;
             }
-            $root_tree_oid = $this->get_commit_tree_oid();
+            $root_tree_oid = $this->get_parsed_commit()['tree'] ?? null;
+        }
+        if($root_tree_oid === null) {
+            return false;
         }
         if(false === $this->read_object($root_tree_oid)) {
             return false;
@@ -93,41 +207,90 @@ public function read_by_path($path, $root_tree_oid=null) {
         return true;
     }
 
-    public function get_descendants($tree_oid) {
-        if(false === $this->read_object($tree_oid)) {
-            return [];
+    public function get_last_error() {
+        return $this->last_error;
+    }
+
+    public function iterate_objects_added_in($new_tree_oid, $old_tree_oid=null) {
+        if($new_tree_oid === $old_tree_oid) {
+            return false;
         }
-        foreach ($this->parsed_tree as $object) {
-            if ($object['mode'] === WP_Git_Pack_Processor::FILE_MODE_DIRECTORY) {
-                yield from $this->get_descendants($object['sha1']);
-            } else {
-                yield $object;
-            }
+
+        // Resolve the actual tree oid if $new_tree_oid is a commit
+        if(false === $this->read_object($new_tree_oid)) {
+            $this->last_error = 'Failed to read object: ' . $new_tree_oid;
+            return false;
+        }
+        if($this->get_type() === WP_Git_Pack_Processor::OBJECT_TYPE_COMMIT) {
+            // yield the commit object itself
+            $parsed_commit = $this->get_parsed_commit();
+            yield $parsed_commit['tree'];
+            $new_tree_oid = $parsed_commit['tree'];
         }
-    }
 
-    public function get_type() {
-        return $this->type;
-    }
+        // Resolve the actual tree oid if $old_tree_oid is a commit
+        if($old_tree_oid) {
+            if(false === $this->read_object($old_tree_oid)) {
+                $this->last_error = 'Failed to read object: ' . $old_tree_oid;
+                return false;
+            }
+            if($this->get_type() === WP_Git_Pack_Processor::OBJECT_TYPE_COMMIT) {
+                $old_tree_oid = $this->get_parsed_commit()['tree'];
+            }
+        }
 
-    public function get_length() {
-        return $this->length;
-    }
+        $stack = [[$new_tree_oid, $old_tree_oid]];
+        
+        while(!empty($stack)) {
+            list($current_new_oid, $current_old_oid) = array_pop($stack);
+            
+            if(false === $this->read_object($current_new_oid)) {
+                $this->last_error = 'Failed to read object: ' . $current_new_oid;
+                return false;
+            }
+            $new_tree = $this->get_parsed_tree();
+            
+            $old_tree = [];
+            if($current_old_oid) {
+                if(false === $this->read_object($current_old_oid)) {
+                    $this->last_error = 'Failed to read object: ' . $current_old_oid;
+                    return false;
+                }
+                $old_tree = $this->get_parsed_tree();
+            }
 
-    public function get_contents() {
-        return $this->contents;
-    }
+            foreach($new_tree as $name => $object) {
+                // Object is new
+                if(!isset($old_tree[$name])) {
+                    if(false === $this->read_object($object['sha1'])) {
+                        $this->last_error = 'Failed to read object: ' . $object['sha1'];
+                        return false;
+                    }
+                    yield $object['sha1'];
+                    if($object['mode'] === WP_Git_Pack_Processor::FILE_MODE_DIRECTORY) {
+                        $stack[] = [$object['sha1'], null];
+                    }
+                    continue;
+                }
 
-    public function get_parsed_commit() {
-        return $this->parsed_commit;
-    }
+                // Object is unchanged
+                if($object['sha1'] === $old_tree[$name]['sha1']) {
+                    continue;
+                }
 
-    public function get_commit_tree_oid() {
-        return $this->parsed_commit['tree'];
-    }
+                if(false === $this->read_object($object['sha1'])) {
+                    $this->last_error = 'Failed to read object: ' . $object['sha1'];
+                    return false;
+                }
+                
+                yield $object['sha1'];
 
-    public function get_parsed_tree() {
-        return $this->parsed_tree;
+                if($object['mode'] === WP_Git_Pack_Processor::FILE_MODE_DIRECTORY) {
+                    // Object is a changed directory - add to stack for recursive processing
+                    $stack[] = [$object['sha1'], $old_tree[$name]['sha1']];
+                }
+            }
+        }
     }
 
     public function set_ref_head($ref, $oid) {
@@ -205,6 +368,7 @@ public function commit($changeset, $commit_meta=[]) {
 
         // Process blob updates
         foreach ($updates as $path => $content) {
+            $path = '/' . ltrim($path, '/');
             $blob_oid = $this->add_object(WP_Git_Pack_Processor::OBJECT_TYPE_BLOB, $content);
             $this->mark_tree_path_changed($changed_trees, dirname($path));
             $changed_trees[dirname($path)]['entries'][basename($path)] = [
@@ -216,6 +380,7 @@ public function commit($changeset, $commit_meta=[]) {
 
         // Process deletes
         foreach ($deletes as $path) {
+            $path = '/' . ltrim($path, '/');
             if (!$this->read_by_path(dirname($path))) {
                 _doing_it_wrong(__METHOD__, 'File not found in HEAD: ' . $path, '1.0.0');
                 return false;
@@ -226,6 +391,8 @@ public function commit($changeset, $commit_meta=[]) {
 
         // Process tree moves
         foreach ($move_trees as $old_path => $new_path) {
+            $old_path = '/' . ltrim($old_path, '/');
+            $new_path = '/' . ltrim($new_path, '/');
             if (!$this->read_by_path($old_path)) {
                 _doing_it_wrong(__METHOD__, 'Path not found in HEAD: ' . $old_path, '1.0.0');
                 return false;
@@ -244,7 +411,7 @@ public function commit($changeset, $commit_meta=[]) {
         // Process trees bottom-up recursively
         $root_tree_oid = $this->commit_tree('/', $changed_trees);
 
-        // Create commit object
+        // Create a new commit object
         $commit_message = [];
         $commit_message[] = "tree " . $root_tree_oid;
         if($this->get_ref_head('HEAD')) {
@@ -262,9 +429,22 @@ public function commit($changeset, $commit_meta=[]) {
             $this->last_error = 'Failed to set HEAD';
             return false;
         }
+        $this->reset();
         return $commit_oid;
     }
 
+    private function reset() {
+        $this->close_object_stream();
+        $this->oid = null;
+        $this->type = null;
+        $this->parsed_commit = null;
+        $this->parsed_tree = null;
+        $this->called_next_object_chunk = false;
+        $this->buffered_object_content = null;
+        $this->object_content_chunk = null;
+        $this->last_error = null;
+    }
+
     private function mark_tree_path_changed(&$changed_trees, $path) {
         while ($path !== '/') {
             if (!isset($changed_trees[$path])) {
@@ -312,4 +492,5 @@ private function commit_tree($path, $changed_trees) {
         );
     }
 
+
 }
diff --git a/packages/playground/data-liberation/src/git/WP_Git_Pack_Processor.php b/packages/playground/data-liberation/src/git/WP_Git_Pack_Processor.php
index d2ab5ba0ac..5d61512f3b 100644
--- a/packages/playground/data-liberation/src/git/WP_Git_Pack_Processor.php
+++ b/packages/playground/data-liberation/src/git/WP_Git_Pack_Processor.php
@@ -269,7 +269,7 @@ static public function parse_commit_message($commit_message) {
         $parsed = [];
         foreach($lines as $k => $line) {
             if(!trim($line)) {
-                $parsed['message'] = array_slice($lines, $k + 1);
+                $parsed['message'] = implode("\n", array_slice($lines, $k + 1));
                 break;
             }
             $type_len = strpos($line, ' ');