diff --git a/.jules/bolt.md b/.jules/bolt.md
new file mode 100644
index 0000000..08f6bb9
--- /dev/null
+++ b/.jules/bolt.md
@@ -0,0 +1,3 @@
+## 2025-02-25 - Avoid leaving random test files when generating patches
+**Learning:** Even when working carefully on isolated performance optimizations using a temporary Gradle setup (`tempTest/`) or ad-hoc scripts (`patch_hint.sh`), it's incredibly important to clean up these files before requesting a code review or submitting a PR. Leaving them pollutes the git working tree, turning an otherwise excellent PR into a blockable state.
+**Action:** Before running `request_code_review` or `submit`, explicitly run a `git status` and actively `rm -rf` all scripts, test files, and temporary directories that are not intended to be part of the final commit.
diff --git a/halogen-core/src/commonMain/kotlin/halogen/SchemaParser.kt b/halogen-core/src/commonMain/kotlin/halogen/SchemaParser.kt
index 4c15627..212069e 100644
--- a/halogen-core/src/commonMain/kotlin/halogen/SchemaParser.kt
+++ b/halogen-core/src/commonMain/kotlin/halogen/SchemaParser.kt
@@ -15,8 +15,6 @@ public object SchemaParser {
         isLenient = true
     }
 
-    private val HEX_COLOR_REGEX: Regex = Regex("^#[0-9A-Fa-f]{6}$")
-
     /**
      * Parse a JSON string (potentially wrapped in markdown code fences) into
      * a validated [HalogenThemeSpec].
@@ -67,7 +65,7 @@ public object SchemaParser {
         )
 
         for ((name, value) in colorFields) {
-            if (!HEX_COLOR_REGEX.matches(value)) {
+            if (!isValidHexColor(value)) {
                 return Result.failure(
                     IllegalArgumentException(
                         "Invalid hex color for $name: \"$value\". Expected format: #RRGGBB",
@@ -85,4 +83,13 @@ public object SchemaParser {
 
         return Result.success(clamped)
     }
+
+    private fun isValidHexColor(value: String): Boolean {
+        if (value.length != 7 || value[0] != '#') return false
+        for (i in 1 until 7) {
+            val c = value[i]
+            if (c !in '0'..'9' && c !in 'a'..'f' && c !in 'A'..'F') return false
+        }
+        return true
+    }
 }
diff --git a/halogen-engine/src/commonMain/kotlin/halogen/engine/HintExtractor.kt b/halogen-engine/src/commonMain/kotlin/halogen/engine/HintExtractor.kt
index da90f01..d3783f9 100644
--- a/halogen-engine/src/commonMain/kotlin/halogen/engine/HintExtractor.kt
+++ b/halogen-engine/src/commonMain/kotlin/halogen/engine/HintExtractor.kt
@@ -10,42 +10,78 @@ package halogen.engine
  */
 internal object HintExtractor {
 
-    private val PREFIX_PATTERN = Regex("""^(?:/r/|/category/|/topic/|/|#)""")
-    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
+        val trimmed = key.trim()
+        var start = 0
+        val len = trimmed.length
 
         // Strip common prefixes
-        var cleaned = PREFIX_PATTERN.replace(key.trim(), "")
+        if (trimmed.startsWith("/r/")) start = 3
+        else if (trimmed.startsWith("/category/")) start = 10
+        else if (trimmed.startsWith("/topic/")) start = 7
+        else if (trimmed.startsWith("/") || trimmed.startsWith("#")) start = 1
 
-        // Remove leading/trailing slashes
-        cleaned = cleaned.trim('/')
+        var end = len
+        while (start < end && trimmed[start] == '/') start++
+        while (start < end && trimmed[end - 1] == '/') end--
 
         // Take the last meaningful segment if it looks like a path
-        if ('/' in cleaned) {
-            cleaned = cleaned.substringAfterLast('/')
+        val lastSlash = trimmed.lastIndexOf('/', end - 1)
+        if (lastSlash >= start) {
+            start = lastSlash + 1
         }
 
-        // Split camelCase
-        cleaned = CAMEL_SPLIT.replace(cleaned, " ")
+        if (start >= end) return null
+
+        val sb = StringBuilder()
+        var hasValidChar = false
+        var isAllHex = true
+        var isAllDigit = true
+        var charCount = 0
+        var spacePending = false
+        var prevWasLower = false
+
+        for (i in start until end) {
+            val c = trimmed[i]
+            if (c == '_' || c == '-' || c.isWhitespace()) {
+                if (hasValidChar) {
+                    spacePending = true
+                }
+                prevWasLower = false
+            } else {
+                val isUpper = c.isUpperCase()
+                val isLower = c.isLowerCase()
 
-        // Split snake_case and kebab-case
-        cleaned = cleaned.replace('_', ' ').replace('-', ' ')
+                // Split camelCase
+                if (prevWasLower && isUpper) {
+                    spacePending = true
+                }
 
-        // Normalize whitespace
-        cleaned = cleaned.trim().replace(WHITESPACE_PATTERN, " ")
+                if (spacePending && hasValidChar) {
+                    sb.append(' ')
+                    spacePending = false
+                }
 
-        if (cleaned.isBlank()) return null
+                sb.append(c.lowercaseChar())
+                hasValidChar = true
+                prevWasLower = isLower
+                charCount++
+
+                // Validation checks
+                if (c !in '0'..'9') {
+                    isAllDigit = false
+                    if (c !in 'a'..'f' && c !in 'A'..'F') {
+                        isAllHex = false
+                    }
+                }
+            }
+        }
 
-        // Reject things that look like IDs
-        val noSpaces = cleaned.replace(" ", "")
-        if (ID_PATTERN.matches(noSpaces)) return null
-        if (NUMERIC_ONLY.matches(noSpaces)) return null
+        if (!hasValidChar) return null
+        if (isAllDigit) return null
+        if (isAllHex && charCount >= 8) return null
 
-        return cleaned.lowercase()
+        return sb.toString()
     }
 }