From 76983a1662abb6267b111264e9de6cb1e9f26554 Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Sun, 10 May 2026 02:45:28 +0000
Subject: [PATCH] =?UTF-8?q?=E2=9A=A1=20Bolt:=20Extract=20dynamic=20Regex?=
 =?UTF-8?q?=20to=20optimize=20HintExtractor=20performance?=
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💡 What: Extracted `Regex("""\s+""")` to a private object-level constant `WHITESPACE_PATTERN` inside `HintExtractor.kt`.
🎯 Why: In Kotlin, dynamically defining `Regex` objects inside functions incurs a performance penalty since they get recompiled on every invocation. Hoisting it prevents this redundant overhead in what could be a hot path.
📊 Impact: Eliminates repetitive regex compilation on string formatting, reducing memory allocations and CPU overhead during hint extraction.
🔬 Measurement: Covered by the existing `HintExtractorTest.kt` test cases. Run `./gradlew :halogen-engine:test` to verify correctness.

Co-authored-by: himattm <6266621+himattm@users.noreply.github.com>
---
 .jules/bolt.md                                                 | 3 +++
 .../src/commonMain/kotlin/halogen/engine/HintExtractor.kt      | 3 ++-
 2 files changed, 5 insertions(+), 1 deletion(-)
 create mode 100644 .jules/bolt.md

diff --git a/.jules/bolt.md b/.jules/bolt.md
new file mode 100644
index 0000000..4fa1b15
--- /dev/null
+++ b/.jules/bolt.md
@@ -0,0 +1,3 @@
+## 2026-05-10 - Extract Dynamic Regex Declarations
+**Learning:** In Kotlin, declaring `Regex` objects dynamically within functions incurs a performance penalty due to recompilation on every invocation.
+**Action:** Always hoist frequently used regexes (e.g., `Regex("""\s+""")`) to class-level or object-level constants (e.g., `private val`) to optimize performance in hot paths.
diff --git a/halogen-engine/src/commonMain/kotlin/halogen/engine/HintExtractor.kt b/halogen-engine/src/commonMain/kotlin/halogen/engine/HintExtractor.kt
index c5cb8cb..da90f01 100644
--- a/halogen-engine/src/commonMain/kotlin/halogen/engine/HintExtractor.kt
+++ b/halogen-engine/src/commonMain/kotlin/halogen/engine/HintExtractor.kt
@@ -14,6 +14,7 @@ internal object HintExtractor {
     private val CAMEL_SPLIT = Regex("""(?<=[a-z])(?=[A-Z])""")
     private val ID_PATTERN = Regex("""^[0-9a-f]{8,}$""", RegexOption.IGNORE_CASE)
     private val NUMERIC_ONLY = Regex("""^\d+$""")
+    private val WHITESPACE_PATTERN = Regex("""\s+""")
 
     fun extract(key: String): String? {
         if (key.isBlank()) return null
@@ -36,7 +37,7 @@ internal object HintExtractor {
         cleaned = cleaned.replace('_', ' ').replace('-', ' ')
 
         // Normalize whitespace
-        cleaned = cleaned.trim().replace(Regex("""\s+"""), " ")
+        cleaned = cleaned.trim().replace(WHITESPACE_PATTERN, " ")
 
         if (cleaned.isBlank()) return null