chore: mark completed items in PLAN.md as DONE

Co-authored-by: aider (openai/andrew/openrouter/qwen/qwen3-coder) <aider@aider.chat>

PLAN.md

@@ -2,19 +2,19 @@
 
 ## Critical Issues
 
-### 1. Memory Safety & Resource Leaks
+### 1. Memory Safety & Resource Leaks - DONE
 **Files affected:** `src/modes/diff.rs`, `src/compression_engine/program.rs`
 **Functions affected:** `mode_diff()`, `CompressionEngineProgram::open()`, `CompressionEngineProgram::create()`
 **Problem example:** Raw file descriptors converted with `unsafe { std::fs::File::from_raw_fd(fd_write) }` without proper cleanup on errors
 **Fix example:** Use RAII wrappers or ensure proper cleanup in Drop implementations and error paths
 
-### 2. Error Handling Problems
+### 2. Error Handling Problems - DONE
 **Files affected:** `src/modes/save.rs`, `src/modes/update.rs`, `src/db.rs`
 **Functions affected:** `mode_save()`, `mode_update()`, `get_item()`, `insert_item()`
 **Problem example:** `item.id.unwrap()` can panic if item.id is None
 **Fix example:** Replace with `item.id.ok_or_else(|| anyhow!("Item missing ID"))?`
 
-### 3. Concurrency Issues
+### 3. Concurrency Issues - DONE
 **Files affected:** `src/modes/diff.rs`, `src/meta_plugin/digest.rs`
 **Functions affected:** `mode_diff()`, meta plugin `update()` methods
 **Problem example:** In `mode_diff()`, if writer threads panic, resources may not be cleaned up properly: `writer_thread_a.join()` only propagates panic but doesn't ensure file descriptors are closed
@@ -22,7 +22,7 @@
 
 ## Design Problems
 
-### 4. Database Design Issues
+### 4. Database Design Issues - DONE
 **Files affected:** `src/db.rs`, `src/modes/save.rs`, `src/modes/update.rs`
 **Functions affected:** `insert_item()`, `update_item()`, `store_meta()`, `set_item_tags()`
 **Problem example:** Multiple database operations without transactions can leave partial state
@@ -41,7 +41,7 @@
 - Reuse single process per plugin instance for better performance
 - Add output validation and proper error propagation
 
-### 6. Security Concerns
+### 6. Security Concerns - DONE
 **Files affected:** `src/main.rs`, `src/modes/get.rs`, `src/modes/delete.rs`
 **Functions affected:** `main()`, `mode_get()`, `mode_delete()`
 **Problem example:** Item IDs used directly in file paths without validation: `item_path.push(item_id.to_string())`