diff --git a/CHANGELOG.md b/CHANGELOG.md
index e324a5460b3..18f8aa8301d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -27,6 +27,7 @@ Docs: https://docs.openclaw.ai
 ### Fixes
 
 - Agents/compaction safeguard pre-check: skip embedded compaction before entering the Pi SDK when a session has no real conversation messages, avoiding unnecessary LLM API calls on idle sessions. (#36451) thanks @Sid-Qin.
+- Config/schema cache key stability: build merged schema cache keys with incremental hashing to avoid large single-string serialization and prevent `RangeError: Invalid string length` on high-cardinality plugin/channel metadata. (#36603) Thanks @powermaster888.
 - iMessage/cron completion announces: strip leaked inline reply tags (for example `[[reply_to:6100]]`) from user-visible completion text so announcement deliveries do not expose threading metadata. (#24600) Thanks @vincentkoc.
 - Sessions/daily reset transcript archival: archive prior transcript files during stale-session scheduled/daily resets by capturing the previous session entry before rollover, preventing orphaned transcript files on disk. (#35493) Thanks @byungsker.
 - Feishu/group slash command detection: normalize group mention wrappers before command-authorization probing so mention-prefixed commands (for example `@Bot/model` and `@Bot /reset`) are recognized as gateway commands instead of being forwarded to the agent. (#35994) Thanks @liuxiaopai-ai.
diff --git a/src/config/schema.ts b/src/config/schema.ts
index 58d93215de1..406d61dce77 100644
--- a/src/config/schema.ts
+++ b/src/config/schema.ts
@@ -1,3 +1,4 @@
+import crypto from "node:crypto";
 import { CHANNEL_IDS } from "../channels/registry.js";
 import { VERSION } from "../version.js";
 import type { ConfigUiHint, ConfigUiHints } from "./schema.hints.js";
@@ -322,7 +323,24 @@ function buildMergedSchemaCacheKey(params: {
       configUiHints: channel.configUiHints ?? null,
     }))
     .toSorted((a, b) => a.id.localeCompare(b.id));
-  return JSON.stringify({ plugins, channels });
+  // Build the hash incrementally so we never materialize one giant JSON string.
+  const hash = crypto.createHash("sha256");
+  hash.update('{"plugins":[');
+  plugins.forEach((plugin, index) => {
+    if (index > 0) {
+      hash.update(",");
+    }
+    hash.update(JSON.stringify(plugin));
+  });
+  hash.update('],"channels":[');
+  channels.forEach((channel, index) => {
+    if (index > 0) {
+      hash.update(",");
+    }
+    hash.update(JSON.stringify(channel));
+  });
+  hash.update("]}");
+  return hash.digest("hex");
 }
 
 function setMergedSchemaCache(key: string, value: ConfigSchemaResponse): void {