⚡ Optimize string formatting and fast-path in CLI migrate tool

.jules/bolt.md

@@ -8,6 +8,4 @@
 ## 2024-05-18 - Removed redundant clone of VM stack during trace logs
 **Learning:** In `runtime/vm/src/executor.rs`, the debugging instruction trace `self.debugger.trace_instruction` was cloning the entire VM stack using `&self.stack.get_dump()` for every single instruction executed. This caused significant `O(N)` overhead inside the main fetch-decode-execute loop just to format debug output. A new `data_slice()` method was added to `ValueStack` to provide zero-copy slice access (`&[RuntimeValue]`) instead, completely eliminating the allocation overhead.
 **Action:** Always scrutinize deep clones in logging, tracing, or hot path loops. Use slice references (`&[T]`) instead of `Vec::clone` when the caller only needs read-only access to a collection.
-## 2024-06-25 - Suboptimal Line Search in LSP
-**Learning:** Using `chars().nth()` with a byte offset (such as one returned by `.find()`) inside a loop over a string creates an O(N) penalty and may result in an incorrect character lookup if multi-byte unicode characters are present.
-**Action:** Use string slicing with the byte index to create a subset string slice, and call `.chars().next_back()` or `.chars().next()` on it for an O(1) and UTF-8 safe boundary lookup.
+<

cli/src/commands/migrate.rs

@@ -250,10 +250,17 @@ fn post_process(source: &str) -> String {
 /// Replace `prefix(args)` calls with `keyword args` (implicit call style).
 fn replace_call(source: &str, prefix: &str, keyword: &str) -> String {
     let full = format!("{prefix}(");
+    let full_str = full.as_str();
+
+    // Fast path: if the substring is not in the source, just return a copy.
+    if !source.contains(full_str) {
+        return source.to_string();
+    }
+
     let mut result = String::with_capacity(source.len());
     let mut remaining = source;
     loop {
-        match remaining.find(full.as_str()) {
+        match remaining.find(full_str) {
             None => {
                 result.push_str(remaining);
                 break;

docs/benchmarks/benchmark_report.md

@@ -5,12 +5,12 @@ Generated on standard test environment (Windows target execution).
 ## Compilation Phase Speeds
 | Phase | Duration |
 | :--- | :--- |
-| **Lexing & Tokenization** | 0.092 ms |
-| **Pratt Parsing & AST Building** | 0.116 ms |
-| **Semantic Check & Name Binding** | 0.199 ms |
-| **SSA IR Lowering & Optimization** | 0.194 ms |
-| **Bytecode Generation** | 0.110 ms |
-| **VM Execution (Fibonacci 25)** | 38629.399 ms |
+| **Lexing & Tokenization** | 0.090 ms |
+| **Pratt Parsing & AST Building** | 0.245 ms |
+| **Semantic Check & Name Binding** | 0.454 ms |
+| **SSA IR Lowering & Optimization** | 0.103 ms |
+| **Bytecode Generation** | 0.138 ms |
+| **VM Execution (Fibonacci 25)** | 1279.449 ms |
 
 ## Benchmark Details
 - **Test File**: Recursive Fibonacci 25 calculation (`fib(25)`)