From 06e48e212ec0e9dd4c5ff8803111172e7ed2f86d Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Wed, 23 Sep 2026 05:07:39 +0000
Subject: [PATCH] =?UTF-8?q?=E2=9A=A1=20Bolt:=20Replace=20iterative=20hex?=
 =?UTF-8?q?=20formatting=20with=20single-allocation=20hex::encode?=
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Co-authored-by: Tcode-Motion <188012755+Tcode-Motion@users.noreply.github.com>
---
 .jules/bolt.md         | 3 +++
 stdlib/src/crypto.rs   | 6 ++----
 stdlib/src/security.rs | 6 ++++--
 test_perf.rs           | 3 ---
 4 files changed, 9 insertions(+), 9 deletions(-)
 delete mode 100644 test_perf.rs

diff --git a/.jules/bolt.md b/.jules/bolt.md
index ff826971..362f27c6 100644
--- a/.jules/bolt.md
+++ b/.jules/bolt.md
@@ -35,3 +35,6 @@
 ## 2024-05-24 - Canvas Property Extraction Optimization
 **Learning:** Extracting properties from the `RuntimeValue` DSL property lists in `canvas.rs` was inefficient because the code called `.iter().find()` multiple times for each property in `logo`, `rings`, `emblem`, `letter`, `core`, and `circuits` definitions.
 **Action:** Replace multiple `.find()` calls with a single-pass `for p in &dsl.properties` loop and `match` on the property names, mutating local fallback variables.
+## 2024-11-20 - Avoid `format!` inside loops for hex string encoding
+**Learning:** Using `.iter().map(|b| format!("{:02x}", b)).collect::<String>()` to encode a byte array to a hex string incurs a heavy performance penalty because it allocates a new temporary `String` for every single byte processed before concatenating them. The `hex::encode()` function from the `hex` crate performs this conversion directly into a single pre-allocated `String` with zero intermediate allocations.
+**Action:** Always prefer `hex::encode(bytes)` over iterative `format!` mapping when performing hexadecimal encoding of byte arrays or slices to eliminate intermediate string allocations and significantly boost performance.
diff --git a/stdlib/src/crypto.rs b/stdlib/src/crypto.rs
index a7b97e60..54a9cd19 100644
--- a/stdlib/src/crypto.rs
+++ b/stdlib/src/crypto.rs
@@ -61,10 +61,8 @@ impl StdlibRegistry {
                     combined.extend_from_slice(&ciphertext);
 
                     // Hex encode ciphertext
-                    let hex_ciphertext = combined
-                        .iter()
-                        .map(|b| format!("{:02x}", b))
-                        .collect::<String>();
+                    // ⚡ Bolt Performance Optimization: Replaced iterative format! with hex::encode for single-allocation hex string conversion.
+                    let hex_ciphertext = hex::encode(combined);
                     Ok(RuntimeValue::Str(hex_ciphertext))
                 },
             }),
diff --git a/stdlib/src/security.rs b/stdlib/src/security.rs
index c19542b1..e92faab6 100644
--- a/stdlib/src/security.rs
+++ b/stdlib/src/security.rs
@@ -18,7 +18,8 @@ impl StdlibRegistry {
                     use rand::Rng;
                     let bytes: Vec<u8> =
                         rand::thread_rng().gen::<[u8; 32]>()[..len.min(32)].to_vec();
-                    let hex: String = bytes.iter().map(|b| format!("{:02x}", b)).collect();
+                    // ⚡ Bolt Performance Optimization: Replaced iterative format! with hex::encode for single-allocation hex string conversion.
+                    let hex = hex::encode(bytes);
                     Ok(RuntimeValue::Str(hex))
                 },
             }),
@@ -48,7 +49,8 @@ impl StdlibRegistry {
                     let input = args[0].to_string();
                     use sha2::Digest;
                     let digest = sha2::Sha256::digest(input.as_bytes());
-                    let hex: String = digest.iter().map(|b| format!("{:02x}", b)).collect();
+                    // ⚡ Bolt Performance Optimization: Replaced iterative format! with hex::encode for single-allocation hex string conversion.
+                    let hex = hex::encode(digest);
                     Ok(RuntimeValue::Str(hex))
                 },
             }),
diff --git a/test_perf.rs b/test_perf.rs
deleted file mode 100644
index 8093e40b..00000000
--- a/test_perf.rs
+++ /dev/null
@@ -1,3 +0,0 @@
-fn main() {
-    println!("Testing performance...");
-}