fix: implement type-aware sanitization for thinking blocks (#27825)

- Add sanitizePayload() with structural traversal
- Bypass sanitization for signed thinking blocks
- Preserve normal sanitization for other content
- Config-driven toggle for flexible deployment
- Replace runtime patching with clean code solution

Supersedes #27965

lib/utils/sanitizePayload.js

@@ -0,0 +1,47 @@
+/**
+ * Type-Aware Sanitization for OpenClaw Issue #27825
+ * Prevents sanitizeSurrogates() from corrupting signed Anthropic thinking blocks
+ */
+
+import { sanitizeSurrogates } from './surrogate-sanitizer.js';
+
+/**
+ * Sanitizes payload while preserving thinking blocks with valid signatures
+ * @param {any} payload - The payload to sanitize
+ * @param {Object} options - Configuration options
+ * @param {boolean} options.preserveThinkingBlocks - Whether to bypass thinking block sanitization
+ * @returns {any} Sanitized payload
+ */
+export function sanitizePayload(payload, options = {}) {
+  const { preserveThinkingBlocks = false } = options;
+  
+  function traverseAndSanitize(node) {
+    // Bypass thinking blocks if preservation is enabled
+    if (preserveThinkingBlocks && node?.type === 'thinking' && node?.signature) {
+      return node;
+    }
+    
+    // Sanitize strings
+    if (typeof node === 'string') {
+      return sanitizeSurrogates(node);
+    }
+    
+    // Handle arrays
+    if (Array.isArray(node)) {
+      return node.map(traverseAndSanitize);
+    }
+    
+    // Handle objects
+    if (node && typeof node === 'object') {
+      const result = {};
+      for (const key of Object.keys(node)) {
+        result[key] = traverseAndSanitize(node[key]);
+      }
+      return result;
+    }
+    
+    return node;
+  }
+  
+  return traverseAndSanitize(payload);
+}

openclaw-2026-03-19.log

@@ -0,0 +1 @@
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openclaw-2026-03-20.log

@@ -0,0 +1,2 @@
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+{"0":"{\"subsystem\":\"agents/tool-images\"}","1":{"label":"session:history","sourceMimeType":"image/png","sourceWidth":1341,"sourceHeight":366,"sourceBytes":29177,"maxBytes":5242880,"maxDimensionPx":1200,"triggerOverBytes":false,"triggerOverDimensions":true,"outputMimeType":"image/jpeg","outputBytes":35088,"outputQuality":85,"outputMaxSide":1200,"byteReductionPct":-20.3},"2":"Image resized to fit limits: 1341x366px 28.5KB -> 34.3KB (--20.3%)","_meta":{"runtime":"node","runtimeVersion":"24.14.0","hostname":"unknown","name":"{\"subsystem\":\"agents/tool-images\"}","parentNames":["openclaw"],"date":"2026-03-20T14:02:14.287Z","logLevelId":3,"logLevelName":"INFO","path":{"fullFilePath":"file:///home/botty/.npm-global/lib/node_modules/openclaw/dist/subsystem-BDbeCphF.js:1118:51","fileName":"subsystem-BDbeCphF.js","fileNameWithLine":"subsystem-BDbeCphF.js:1118","fileColumn":"51","fileLine":"1118","filePath":".npm-global/lib/node_modules/openclaw/dist/subsystem-BDbeCphF.js","filePathWithLine":".npm-global/lib/node_modules/openclaw/dist/subsystem-BDbeCphF.js:1118","method":"logToFile"}},"time":"2026-03-20T15:02:14.287+01:00"}