From a1d5aebc05f77594c604aed6b8d4de873dbc453f Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Sun, 26 Apr 2026 02:31:46 +0000
Subject: [PATCH 1/2] =?UTF-8?q?=E2=9A=A1=20Bolt:=20WasmJs=20ThemeCache=20O?=
 =?UTF-8?q?ptimization?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: himattm <6266621+himattm@users.noreply.github.com>
---
 .jules/bolt.md                                 |  3 +++
 .../halogen/engine/LocalStorageThemeCache.kt   | 18 ++++++++++++++----
 2 files changed, 17 insertions(+), 4 deletions(-)
 create mode 100644 .jules/bolt.md

diff --git a/.jules/bolt.md b/.jules/bolt.md
new file mode 100644
index 0000000..303f8fd
--- /dev/null
+++ b/.jules/bolt.md
@@ -0,0 +1,3 @@
+## 2024-05-18 - WasmJs ThemeCache Optimization
+**Learning:** JSON decoding in Kotlin Multiplatform for WasmJs targets carries significant overhead. The existing LocalStorageThemeCache reads from `localStorage` and decodes a JSON manifest of strings every time `readManifest()` is called. This is a very common operation because it's called on almost every write and cache query operation (`put`, `evict`, `clear`, `keys`, `size`, `entries`).
+**Action:** Implement an in-memory `manifestCache: MutableSet<String>?` initialized via `lazy` or checked and set so we don't have to parse JSON from localStorage every time.
diff --git a/halogen-engine/src/wasmJsMain/kotlin/halogen/engine/LocalStorageThemeCache.kt b/halogen-engine/src/wasmJsMain/kotlin/halogen/engine/LocalStorageThemeCache.kt
index aba1f32..b34898f 100644
--- a/halogen-engine/src/wasmJsMain/kotlin/halogen/engine/LocalStorageThemeCache.kt
+++ b/halogen-engine/src/wasmJsMain/kotlin/halogen/engine/LocalStorageThemeCache.kt
@@ -48,19 +48,28 @@ public class LocalStorageThemeCache(
     private val _changes = MutableSharedFlow<CacheEvent>(extraBufferCapacity = 64)
     private val json = Json { ignoreUnknownKeys = true }
     private val manifestKey = "${prefix}__keys__"
+    private var manifestCache: MutableSet<String>? = null
 
     // ── Manifest helpers ────────────────────────────────────────────────
 
     private fun readManifest(): MutableSet<String> {
-        val raw = jsGetItem(manifestKey.toJsString())?.toString() ?: return mutableSetOf()
-        return try {
-            json.decodeFromString<Set<String>>(raw).toMutableSet()
-        } catch (_: Exception) {
+        manifestCache?.let { return it }
+        val raw = jsGetItem(manifestKey.toJsString())?.toString()
+        val parsed = if (raw == null) {
             mutableSetOf()
+        } else {
+            try {
+                json.decodeFromString<Set<String>>(raw).toMutableSet()
+            } catch (_: Exception) {
+                mutableSetOf()
+            }
         }
+        manifestCache = parsed
+        return parsed
     }
 
     private fun writeManifest(keys: Set<String>) {
+        manifestCache = keys.toMutableSet()
         val encoded = json.encodeToString(keys)
         jsSetItem(manifestKey.toJsString(), encoded.toJsString())
     }
@@ -154,6 +163,7 @@ public class LocalStorageThemeCache(
         for (key in manifest) {
             removeEntry("$prefix$key")
         }
+        manifestCache = mutableSetOf()
         jsRemoveItem(manifestKey.toJsString())
         _changes.tryEmit(CacheEvent.Cleared)
     }

From 2e61fdcc6dbde1e6e3f51309bb5d36e8db2fae13 Mon Sep 17 00:00:00 2001
From: Matt Mckenna <mmckenna@pm.me>
Date: Thu, 7 May 2026 09:05:54 -0400
Subject: [PATCH 2/2] chore: drop generated bolt notes

---
 .jules/bolt.md | 3 ---
 1 file changed, 3 deletions(-)
 delete mode 100644 .jules/bolt.md

diff --git a/.jules/bolt.md b/.jules/bolt.md
deleted file mode 100644
index 303f8fd..0000000
--- a/.jules/bolt.md
+++ /dev/null
@@ -1,3 +0,0 @@
-## 2024-05-18 - WasmJs ThemeCache Optimization
-**Learning:** JSON decoding in Kotlin Multiplatform for WasmJs targets carries significant overhead. The existing LocalStorageThemeCache reads from `localStorage` and decodes a JSON manifest of strings every time `readManifest()` is called. This is a very common operation because it's called on almost every write and cache query operation (`put`, `evict`, `clear`, `keys`, `size`, `entries`).
-**Action:** Implement an in-memory `manifestCache: MutableSet<String>?` initialized via `lazy` or checked and set so we don't have to parse JSON from localStorage every time.