⚡ Bolt: optimize string allocations in secret processing

.Jules/bolt.md

@@ -0,0 +1,3 @@
+## 2026-07-18 - Zero-Cost Abstractions in String Manipulation
+**Learning:** Chaining `format!()` macros and `.collect::<Vec<char>>` on short configuration strings in hot loops causes massive heap allocation overhead. `Vec<char>` allocates `4 * N` bytes plus structural overhead just to look at the first and last element of a string.
+**Action:** When working with strings where capacity can be pre-calculated (like concatenating known lengths) or where parsing bounds is needed (like finding the first and last char), always use `String::with_capacity()` or iterator mapping (`chars()`) directly. This reduces allocations to a single, sized heap structure, making the hot path substantially faster.

src/utils/secrets/mod.rs

@@ -121,21 +121,33 @@ fn get_object_identifier(map: &serde_json::Map<String, Value>) -> Option<String>
 
 /// Helper to format environment variable names
 fn format_env_var_name(prefix: &str, key: &str) -> String {
-    let env_var_name = if prefix.is_empty() {
-        format!("KEYCLOAK_{}", key)
-    } else {
-        format!("KEYCLOAK_{}_{}", prefix, key)
-    };
-    env_var_name
-        .chars()
-        .map(|c| {
-            if c.is_alphanumeric() {
+    // Pre-calculate capacity to avoid reallocations: "KEYCLOAK_" + prefix + "_" + key
+    let capacity =
+        "KEYCLOAK_".len() + prefix.len() + if prefix.is_empty() { 0 } else { 1 } + key.len();
+    let mut out = String::with_capacity(capacity);
+
+    out.push_str("KEYCLOAK_");
+
+    if !prefix.is_empty() {
+        for c in prefix.chars() {
+            out.push(if c.is_alphanumeric() {
                 c.to_ascii_uppercase()
             } else {
                 '_'
-            }
-        })
-        .collect()
+            });
+        }
+        out.push('_');
+    }
+
+    for c in key.chars() {
+        out.push(if c.is_alphanumeric() {
+            c.to_ascii_uppercase()
+        } else {
+            '_'
+        });
+    }
+
+    out
 }
 
 /// Recursively extract secrets and replace them with ${ENV_VAR}
@@ -228,13 +240,27 @@ fn obfuscate_string(s: &str) -> String {
         return s.to_string();
     }
 
-    let chars: Vec<char> = s.chars().collect();
-    if chars.len() <= 3 {
+    let mut chars = s.chars();
+    // String is not empty, so next() will return Some
+    let first = chars.next().unwrap();
+
+    let mut count = 1;
+    let mut last = first;
+
+    for c in chars {
+        last = c;
+        count += 1;
+    }
+
+    if count <= 3 {
         return "***".to_string();
     }
-    let first = chars[0];
-    let last = chars[chars.len() - 1];
-    format!("{}***{}", first, last)
+
+    let mut out = String::with_capacity(first.len_utf8() + 3 + last.len_utf8());
+    out.push(first);
+    out.push_str("***");
+    out.push(last);
+    out
 }
 
 /// Recursively obfuscate known secret fields