fix(agents): set preserveSignatures to isAnthropic in resolveTranscriptPolicy (#32813)

Merged via squash.

Prepared head SHA: f522d21ca59a42abac554435a0aa646f6a34698d
Co-authored-by: Sid-Qin <201593046+Sid-Qin@users.noreply.github.com>
Co-authored-by: jalehman <550978+jalehman@users.noreply.github.com>
Reviewed-by: @jalehman

CHANGELOG.md

@@ -31,6 +31,7 @@ Docs: https://docs.openclaw.ai
 - 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.
 - Agents/context pruning: guard assistant thinking/text char estimation against malformed blocks (missing `thinking`/`text` strings or null entries) so pruning no longer crashes with malformed provider content. (openclaw#35146) thanks @Sid-Qin.
+- Agents/transcript policy: set `preserveSignatures` to Anthropic-only handling in `resolveTranscriptPolicy` so Anthropic thinking signatures are preserved while non-Anthropic providers remain unchanged. (#32813) thanks @Sid-Qin.
 - Agents/schema cleaning: detect Venice + Grok model IDs as xAI-proxied targets so unsupported JSON Schema keywords are stripped before requests, preventing Venice/Grok `Invalid arguments` failures. (openclaw#35355) thanks @Sid-Qin.
 - Skills/native command deduplication: centralize skill command dedupe by canonical `skillName` in `listSkillCommandsForAgents` so duplicate suffixed variants (for example `_2`) are no longer surfaced across interfaces outside Discord. (#27521) thanks @shivama205.
 - Agents/xAI tool-call argument decoding: decode HTML-entity encoded xAI/Grok tool-call argument values (`&`, `"`, `<`, `>`, numeric entities) before tool execution so commands with shell operators and quotes no longer fail with parse errors. (#35276) Thanks @Sid-Qin.

src/agents/transcript-policy.test.ts

@@ -76,6 +76,50 @@ describe("resolveTranscriptPolicy", () => {
     expect(policy.sanitizeMode).toBe("full");
   });
 
+  it("preserves thinking signatures for Anthropic provider (#32526)", () => {
+    const policy = resolveTranscriptPolicy({
+      provider: "anthropic",
+      modelId: "claude-opus-4-5",
+      modelApi: "anthropic-messages",
+    });
+    expect(policy.preserveSignatures).toBe(true);
+  });
+
+  it("preserves thinking signatures for Bedrock Anthropic (#32526)", () => {
+    const policy = resolveTranscriptPolicy({
+      provider: "amazon-bedrock",
+      modelId: "us.anthropic.claude-opus-4-6-v1",
+      modelApi: "bedrock-converse-stream",
+    });
+    expect(policy.preserveSignatures).toBe(true);
+  });
+
+  it("does not preserve signatures for Google provider (#32526)", () => {
+    const policy = resolveTranscriptPolicy({
+      provider: "google",
+      modelId: "gemini-2.0-flash",
+      modelApi: "google-generative-ai",
+    });
+    expect(policy.preserveSignatures).toBe(false);
+  });
+
+  it("does not preserve signatures for OpenAI provider (#32526)", () => {
+    const policy = resolveTranscriptPolicy({
+      provider: "openai",
+      modelId: "gpt-4o",
+      modelApi: "openai",
+    });
+    expect(policy.preserveSignatures).toBe(false);
+  });
+
+  it("does not preserve signatures for Mistral provider (#32526)", () => {
+    const policy = resolveTranscriptPolicy({
+      provider: "mistral",
+      modelId: "mistral-large-latest",
+    });
+    expect(policy.preserveSignatures).toBe(false);
+  });
+
   it("keeps OpenRouter on its existing turn-validation path", () => {
     const policy = resolveTranscriptPolicy({
       provider: "openrouter",

src/agents/transcript-policy.ts

@@ -123,7 +123,7 @@ export function resolveTranscriptPolicy(params: {
       (!isOpenAi && sanitizeToolCallIds) || requiresOpenAiCompatibleToolIdSanitization,
     toolCallIdMode,
     repairToolUseResultPairing,
-    preserveSignatures: false,
+    preserveSignatures: isAnthropic,
     sanitizeThoughtSignatures: isOpenAi ? undefined : sanitizeThoughtSignatures,
     sanitizeThinkingSignatures: false,
     dropThinkingBlocks,