diff --git a/open-sse/executors/antigravity.ts b/open-sse/executors/antigravity.ts
index 83d880cd17..e88599a3a6 100644
--- a/open-sse/executors/antigravity.ts
+++ b/open-sse/executors/antigravity.ts
@@ -93,10 +93,12 @@ export class AntigravityExecutor extends BaseExecutor {
           role = "user";
         }
 
-        // Strip thought parts (no valid signature -> provider rejects).
-        // Also drop entries that become empty after filtering, which can trigger
-        // 400 invalid argument on Gemini 3 Flash through Antigravity.
-        const parts = c.parts?.filter((p) => !p.thought && !p.thoughtSignature) || [];
+        const hasFunctionCall = c.parts?.some((p) => p.functionCall) || false;
+
+        // Antigravity rejects synthetic thought text, but Gemini 3+ requires any
+        // returned thoughtSignature metadata to survive model tool-call turns.
+        const parts =
+          c.parts?.filter((p) => !p.thought && (hasFunctionCall || !p.thoughtSignature)) || [];
         return { ...c, role, parts };
       }) || [];
 
@@ -230,7 +232,6 @@ export class AntigravityExecutor extends BaseExecutor {
       let timedOut = false;
       const timeout = AbortSignal.timeout(SSE_COLLECT_TIMEOUT_MS);
       try {
-         
         while (true) {
           if (signal?.aborted) throw new Error("Request aborted during SSE collection");
           const { done, value } = await Promise.race([
diff --git a/open-sse/executors/github.ts b/open-sse/executors/github.ts
index 5399ae0901..8d0083a495 100644
--- a/open-sse/executors/github.ts
+++ b/open-sse/executors/github.ts
@@ -7,6 +7,18 @@ export class GithubExecutor extends BaseExecutor {
     super("github", PROVIDERS.github);
   }
 
+  getCopilotToken(credentials) {
+    return credentials?.copilotToken || credentials?.providerSpecificData?.copilotToken || null;
+  }
+
+  getCopilotTokenExpiresAt(credentials) {
+    return (
+      credentials?.copilotTokenExpiresAt ||
+      credentials?.providerSpecificData?.copilotTokenExpiresAt ||
+      null
+    );
+  }
+
   buildUrl(model, stream, urlIndex = 0) {
     const targetFormat = getModelTargetFormat("gh", model);
     if (targetFormat === "openai-responses") {
@@ -73,7 +85,21 @@ export class GithubExecutor extends BaseExecutor {
 
   async execute(input: ExecuteInput) {
     const result = await super.execute(input);
-    if (!result || !result.response?.body) return result;
+    if (!result || !result.response) return result;
+
+    if (!input.stream) {
+      // wreq-js clone/text semantics consume the original response body. Materialize
+      // non-streaming responses immediately so downstream code always sees a native
+      // fetch Response with a readable body.
+      const status = result.response.status;
+      const statusText = result.response.statusText;
+      const headers = new Headers(result.response.headers);
+      const payload = await result.response.text();
+      result.response = new Response(payload, { status, statusText, headers });
+      return result;
+    }
+
+    if (!result.response.body) return result;
 
     const isStreaming = input.stream === true;
     const contentType = (result.response.headers.get("content-type") || "").toLowerCase();
@@ -105,7 +131,7 @@ export class GithubExecutor extends BaseExecutor {
   }
 
   buildHeaders(credentials, stream = true) {
-    const token = credentials.copilotToken || credentials.accessToken;
+    const token = this.getCopilotToken(credentials) || credentials.accessToken;
     return {
       Authorization: `Bearer ${token}`,
       "Content-Type": "application/json",
@@ -213,11 +239,12 @@ export class GithubExecutor extends BaseExecutor {
 
   needsRefresh(credentials) {
     // Always refresh if no copilotToken
-    if (!credentials.copilotToken) return true;
+    if (!this.getCopilotToken(credentials)) return true;
 
-    if (credentials.copilotTokenExpiresAt) {
+    const copilotTokenExpiresAt = this.getCopilotTokenExpiresAt(credentials);
+    if (copilotTokenExpiresAt) {
       // Handle both Unix timestamp (seconds) and ISO string
-      let expiresAtMs = credentials.copilotTokenExpiresAt;
+      let expiresAtMs = copilotTokenExpiresAt;
       if (typeof expiresAtMs === "number" && expiresAtMs < 1e12) {
         expiresAtMs = expiresAtMs * 1000; // Convert seconds to ms
       } else if (typeof expiresAtMs === "string") {
diff --git a/open-sse/services/claudeCodeCompatible.ts b/open-sse/services/claudeCodeCompatible.ts
index 51c6349e64..c900bcf35a 100644
--- a/open-sse/services/claudeCodeCompatible.ts
+++ b/open-sse/services/claudeCodeCompatible.ts
@@ -166,12 +166,18 @@ export function buildClaudeCodeCompatibleRequest({
     systemBlocks: preparedClaudeBody?.system as Record<string, unknown>[] | undefined,
     cwd,
     now,
+    preserveCacheControl,
   });
   const resolvedSessionId = sessionId || randomUUID();
   const effort = resolveClaudeCodeCompatibleEffort(sourceBody, normalizedBody, model);
   const maxTokens = resolveClaudeCodeCompatibleMaxTokens(sourceBody, normalizedBody);
   const tools = preparedClaudeBody?.tools
-    ? (preparedClaudeBody.tools as Record<string, unknown>[])
+    ? applyClaudeCodeCompatibleToolCacheStrategy(
+        preparedClaudeBody.tools as Record<string, unknown>[],
+        {
+          preserveExisting: preserveCacheControl,
+        }
+      )
     : buildClaudeCodeCompatibleTools(normalizedBody, sourceBody);
   const toolChoice =
     tools.length > 0
@@ -351,8 +357,10 @@ function buildClaudeCodeCompatibleMessagesFromClaude(
     for (const message of merged) {
       stripCacheControlFromContentBlocks(message.content);
     }
-    applyClaudeCodeCompatibleMessageCacheStrategy(merged);
   }
+  applyClaudeCodeCompatibleMessageCacheStrategy(merged, {
+    preserveExisting: preserveCacheControl,
+  });
 
   if (merged.length === 0) {
     const fallbackText = converted
@@ -379,11 +387,13 @@ function buildClaudeCodeCompatibleSystemBlocks({
   systemBlocks,
   cwd,
   now,
+  preserveCacheControl,
 }: {
   messages: MessageLike[] | undefined;
   systemBlocks?: Array<Record<string, unknown>> | undefined;
   cwd: string;
   now: Date;
+  preserveCacheControl: boolean;
 }) {
   const customSystemBlocks =
     Array.isArray(systemBlocks) && systemBlocks.length > 0
@@ -412,6 +422,15 @@ function buildClaudeCodeCompatibleSystemBlocks({
     blocks.push(systemBlock);
   }
 
+  if (
+    preserveCacheControl &&
+    customSystemBlocks.length > 0 &&
+    !customSystemBlocks.some((block) => hasCacheControl(block))
+  ) {
+    const lastCustomSystemBlock = customSystemBlocks[customSystemBlocks.length - 1];
+    lastCustomSystemBlock.cache_control = { type: "ephemeral", ttl: "1h" };
+  }
+
   return blocks;
 }
 
@@ -448,12 +467,10 @@ function buildClaudeCodeCompatibleTools(
   return rawTools
     .map((tool) => convertClaudeCodeCompatibleTool(tool))
     .filter((tool): tool is Record<string, unknown> => !!tool)
+    .map((tool) => ({ ...tool }))
     .map((tool, index, tools) => {
       if (index !== findLastCacheableToolIndex(tools)) return tool;
-      return {
-        ...tool,
-        cache_control: { type: "ephemeral", ttl: "1h" },
-      };
+      return { ...tool, cache_control: { type: "ephemeral", ttl: "1h" } };
     });
 }
 
@@ -633,7 +650,7 @@ function convertClaudeCodeCompatibleClaudeMessage(
 function extractCustomSystemBlocks(messages: MessageLike[] | undefined) {
   if (!Array.isArray(messages)) return [];
 
-  return messages
+  const blocks = messages
     .filter((message) => {
       const role = String(message?.role || "").toLowerCase();
       return role === "system" || role === "developer";
@@ -645,11 +662,21 @@ function extractCustomSystemBlocks(messages: MessageLike[] | undefined) {
       text,
       cache_control: { type: "ephemeral" },
     }));
+
+  if (blocks.length > 0) {
+    blocks[blocks.length - 1].cache_control = { type: "ephemeral", ttl: "1h" };
+  }
+
+  return blocks;
 }
 
 function applyClaudeCodeCompatibleMessageCacheStrategy(
-  messages: Array<{ role: "user" | "assistant"; content: Array<Record<string, unknown>> }>
+  messages: Array<{ role: "user" | "assistant"; content: Array<Record<string, unknown>> }>,
+  options: {
+    preserveExisting?: boolean;
+  } = {}
 ) {
+  const preserveExisting = options.preserveExisting === true;
   const userIndexes = messages.reduce((indexes, message, index) => {
     if (message.role === "user") indexes.push(index);
     return indexes;
@@ -658,14 +685,28 @@ function applyClaudeCodeCompatibleMessageCacheStrategy(
   const secondToLastUserIndex = userIndexes.length >= 2 ? userIndexes[userIndexes.length - 2] : -1;
 
   if (secondToLastUserIndex >= 0) {
-    markLastContentCacheControl(messages[secondToLastUserIndex].content);
+    markLastContentCacheControl(
+      messages[secondToLastUserIndex].content,
+      undefined,
+      preserveExisting
+    );
   } else if (!hasAssistant && userIndexes.length > 0) {
-    markLastContentCacheControl(messages[userIndexes[userIndexes.length - 1]].content);
+    markLastContentCacheControl(
+      messages[userIndexes[userIndexes.length - 1]].content,
+      undefined,
+      preserveExisting
+    );
+  }
+
+  const lastUserIndex = userIndexes.length > 0 ? userIndexes[userIndexes.length - 1] : -1;
+  const endsOnUser = lastUserIndex === messages.length - 1;
+  if (endsOnUser && lastUserIndex >= 0) {
+    markLastContentCacheControl(messages[lastUserIndex].content, undefined, preserveExisting);
   }
 
   for (let i = messages.length - 1; i >= 0; i--) {
     if (messages[i].role !== "assistant") continue;
-    if (markLastContentCacheControl(messages[i].content)) break;
+    if (markLastContentCacheControl(messages[i].content, undefined, preserveExisting)) break;
   }
 }
 
@@ -675,14 +716,52 @@ function stripCacheControlFromContentBlocks(content: Array<Record<string, unknow
   }
 }
 
-function markLastContentCacheControl(content: Array<Record<string, unknown>>, ttl?: string) {
+function applyClaudeCodeCompatibleToolCacheStrategy(
+  tools: Array<Record<string, unknown>>,
+  options: {
+    preserveExisting?: boolean;
+  } = {}
+) {
+  const preparedTools = tools.map((tool) => ({ ...tool }));
+  const lastCacheableToolIndex = findLastCacheableToolIndex(preparedTools);
+  if (lastCacheableToolIndex < 0) return preparedTools;
+
+  if (options.preserveExisting && preparedTools.some((tool) => hasCacheControl(tool))) {
+    return preparedTools;
+  }
+
+  preparedTools[lastCacheableToolIndex].cache_control = { type: "ephemeral", ttl: "1h" };
+  return preparedTools;
+}
+
+function markLastContentCacheControl(
+  content: Array<Record<string, unknown>>,
+  ttl?: string,
+  preserveExisting = false
+) {
   if (!Array.isArray(content) || content.length === 0) return false;
   const lastBlock = content[content.length - 1];
   if (!lastBlock) return false;
+  if (
+    preserveExisting &&
+    content.some(
+      (block) =>
+        !!block &&
+        typeof block === "object" &&
+        !!readRecord(block)?.cache_control &&
+        typeof readRecord(block)?.cache_control === "object"
+    )
+  ) {
+    return true;
+  }
   lastBlock.cache_control = ttl ? { type: "ephemeral", ttl } : { type: "ephemeral" };
   return true;
 }
 
+function hasCacheControl(value: unknown) {
+  return !!readRecord(value)?.cache_control && typeof readRecord(value)?.cache_control === "object";
+}
+
 function findLastCacheableToolIndex(tools: Array<Record<string, unknown>>) {
   for (let i = tools.length - 1; i >= 0; i--) {
     if (!tools[i].defer_loading) {
diff --git a/open-sse/services/combo.ts b/open-sse/services/combo.ts
index 13e9ffc0b1..e6ba23712b 100644
--- a/open-sse/services/combo.ts
+++ b/open-sse/services/combo.ts
@@ -818,8 +818,8 @@ export async function handleComboChat({
       const { getLKGP } = await import("../../src/lib/localDb");
       const lkgp = await getLKGP(combo.name, combo.id || combo.name);
       if (lkgp) lastKnownGoodProvider = lkgp;
-    } catch {
-      /* ignore db errors */
+    } catch (err) {
+      log.warn("COMBO", "Failed to retrieve Last Known Good Provider. This is non-fatal.", { err });
     }
 
     const candidates = await buildAutoCandidates(eligibleModels, combo.name);
@@ -998,7 +998,11 @@ export async function handleComboChat({
         if (provider) {
           import("../../src/lib/localDb")
             .then(({ setLKGP }) => setLKGP(combo.name, combo.id || combo.name, provider))
-            .catch(() => {});
+            .catch((err) =>
+              log.warn("COMBO", "Failed to record Last Known Good Provider. This is non-fatal.", {
+                err,
+              })
+            );
         }
 
         return result;
@@ -1010,17 +1014,16 @@ export async function handleComboChat({
       try {
         const cloned = result.clone();
         try {
-          const errorBody = await cloned.json();
-          errorText =
-            errorBody?.error?.message || errorBody?.error || errorBody?.message || errorText;
-          retryAfter = errorBody?.retryAfter || null;
-        } catch {
-          try {
-            const text = await result.text();
-            if (text) errorText = text.substring(0, 500);
-          } catch {
-            /* Body consumed */
+          const text = await cloned.text();
+          if (text) {
+            errorText = text.substring(0, 500);
+            const errorBody = JSON.parse(text);
+            errorText =
+              errorBody?.error?.message || errorBody?.error || errorBody?.message || errorText;
+            retryAfter = errorBody?.retryAfter || null;
           }
+        } catch {
+          /* Clone parse failed */
         }
       } catch {
         /* Clone failed */
@@ -1293,17 +1296,16 @@ async function handleRoundRobinCombo({
         try {
           const cloned = result.clone();
           try {
-            const errorBody = await cloned.json();
-            errorText =
-              errorBody?.error?.message || errorBody?.error || errorBody?.message || errorText;
-            retryAfter = errorBody?.retryAfter || null;
-          } catch {
-            try {
-              const text = await result.text();
-              if (text) errorText = text.substring(0, 500);
-            } catch {
-              /* Body consumed */
+            const text = await cloned.text();
+            if (text) {
+              errorText = text.substring(0, 500);
+              const errorBody = JSON.parse(text);
+              errorText =
+                errorBody?.error?.message || errorBody?.error || errorBody?.message || errorText;
+              retryAfter = errorBody?.retryAfter || null;
             }
+          } catch {
+            /* Clone parse failed */
           }
         } catch {
           /* Clone failed */
diff --git a/open-sse/services/geminiThoughtSignatureStore.ts b/open-sse/services/geminiThoughtSignatureStore.ts
new file mode 100644
index 0000000000..f52d7a8821
--- /dev/null
+++ b/open-sse/services/geminiThoughtSignatureStore.ts
@@ -0,0 +1,44 @@
+const MAX_SIGNATURES = 1000;
+const TTL_MS = 1000 * 60 * 60;
+
+type Entry = {
+  signature: string;
+  expiresAt: number;
+};
+
+const signatures = new Map<string, Entry>();
+
+function pruneExpired() {
+  const now = Date.now();
+  for (const [key, value] of signatures.entries()) {
+    if (value.expiresAt <= now) {
+      signatures.delete(key);
+    }
+  }
+
+  while (signatures.size > MAX_SIGNATURES) {
+    const oldestKey = signatures.keys().next().value;
+    if (!oldestKey) break;
+    signatures.delete(oldestKey);
+  }
+}
+
+export function storeGeminiThoughtSignature(toolCallId: unknown, signature: unknown) {
+  if (typeof toolCallId !== "string" || !toolCallId) return;
+  if (typeof signature !== "string" || !signature) return;
+
+  pruneExpired();
+  signatures.set(toolCallId, {
+    signature,
+    expiresAt: Date.now() + TTL_MS,
+  });
+}
+
+export function getGeminiThoughtSignature(toolCallId: unknown) {
+  if (typeof toolCallId !== "string" || !toolCallId) return null;
+
+  pruneExpired();
+  const entry = signatures.get(toolCallId);
+  if (!entry) return null;
+  return entry.signature;
+}
diff --git a/open-sse/translator/request/claude-to-gemini.ts b/open-sse/translator/request/claude-to-gemini.ts
index dc4212ec95..2cee5d98f7 100644
--- a/open-sse/translator/request/claude-to-gemini.ts
+++ b/open-sse/translator/request/claude-to-gemini.ts
@@ -92,9 +92,6 @@ export function claudeToGeminiRequest(model, body, stream) {
               break;
 
             case "tool_use":
-              // Do NOT include thoughtSignature on functionCall parts — it is only valid
-              // on thinking/reasoning parts and causes HTTP 400 "invalid argument" from the
-              // Gemini API when present on a functionCall part.
               parts.push({
                 functionCall: {
                   id: block.id,
@@ -148,19 +145,20 @@ export function claudeToGeminiRequest(model, body, stream) {
         // Map Claude roles to Gemini roles
         const geminiRole = msg.role === "assistant" ? "model" : "user";
 
-        // Gemini 3+ requires thoughtSignature as a sibling part in model content
-        // that contains functionCall parts. Inject if not already present from
-        // a thinking block. (#927)
+        // Gemini 3+ expects the signature on the first functionCall part in a tool-call
+        // batch. If the assistant turn had no explicit thinking block, inject a fallback
+        // signature into that first functionCall. (#927)
         if (geminiRole === "model") {
           const hasFunctionCall = parts.some((p) => p.functionCall);
           const hasSignature = parts.some((p) => p.thoughtSignature);
           if (hasFunctionCall && !hasSignature) {
-            // Insert before the first functionCall part
             const fcIndex = parts.findIndex((p) => p.functionCall);
-            parts.splice(fcIndex, 0, {
-              thoughtSignature: DEFAULT_THINKING_GEMINI_SIGNATURE,
-              text: "",
-            });
+            if (fcIndex >= 0) {
+              parts[fcIndex] = {
+                ...parts[fcIndex],
+                thoughtSignature: DEFAULT_THINKING_GEMINI_SIGNATURE,
+              };
+            }
           }
         }
 
diff --git a/open-sse/translator/request/openai-to-gemini.ts b/open-sse/translator/request/openai-to-gemini.ts
index fafe9c6796..96431330dc 100644
--- a/open-sse/translator/request/openai-to-gemini.ts
+++ b/open-sse/translator/request/openai-to-gemini.ts
@@ -2,6 +2,7 @@ import { register } from "../registry.ts";
 import { FORMATS } from "../formats.ts";
 import { DEFAULT_THINKING_GEMINI_SIGNATURE } from "../../config/defaultThinkingSignature.ts";
 import { ANTIGRAVITY_DEFAULT_SYSTEM } from "../../config/constants.ts";
+import { getGeminiThoughtSignature } from "../../services/geminiThoughtSignatureStore.ts";
 import { openaiToClaudeRequestForAntigravity } from "./openai-to-claude.ts";
 import {
   capMaxOutputTokens,
@@ -74,6 +75,15 @@ type CloudCodeEnvelope = {
   };
 };
 
+function normalizeAntigravityToolName(name: unknown) {
+  if (typeof name !== "string") return name;
+  const trimmed = name.trim();
+  if (!trimmed) return trimmed;
+
+  const namespaceIndex = trimmed.indexOf(":");
+  return namespaceIndex >= 0 ? trimmed.slice(namespaceIndex + 1) : trimmed;
+}
+
 // Core: Convert OpenAI request to Gemini format (base for all variants)
 function openaiToGeminiBase(model, body, stream) {
   const result: GeminiRequest = {
@@ -167,31 +177,40 @@ function openaiToGeminiBase(model, body, stream) {
         }
 
         if (msg.tool_calls && Array.isArray(msg.tool_calls)) {
-          // Gemini 3+ requires thoughtSignature as a sibling part in model content
-          // that contains functionCall parts. If no reasoning_content was present
-          // (which already injects the signature above), inject one now. (#927)
-          const hasSignatureAlready = parts.some((p) => p.thoughtSignature);
-          if (!hasSignatureAlready) {
-            parts.push({
-              thoughtSignature: DEFAULT_THINKING_GEMINI_SIGNATURE,
-            });
-          }
-
           const toolCallIds = [];
+          const firstPersistedSignature = msg.tool_calls
+            .map((tc) => getGeminiThoughtSignature(tc.id))
+            .find((signature) => typeof signature === "string" && signature.length > 0);
+
+          const shouldUseEmbeddedSignature = !parts.some((p) => p.thoughtSignature);
+          let embeddedSignatureUsed = false;
+
           for (const tc of msg.tool_calls) {
             if (tc.type !== "function") continue;
 
             const args = tryParseJSON(tc.function?.arguments || "{}");
-            // Do NOT include thoughtSignature ON the functionCall part itself — it is
-            // only valid as a separate sibling part. Including it inside functionCall
-            // causes HTTP 400 "invalid argument" (#725).
+            const signatureForToolCall = getGeminiThoughtSignature(tc.id);
+            const embeddedThoughtSignature =
+              shouldUseEmbeddedSignature && !embeddedSignatureUsed
+                ? firstPersistedSignature ||
+                  signatureForToolCall ||
+                  DEFAULT_THINKING_GEMINI_SIGNATURE
+                : undefined;
+
+            // Gemini expects the signature on the functionCall part itself. For
+            // parallel calls, only the first functionCall in the batch carries it.
             parts.push({
+              ...(embeddedThoughtSignature ? { thoughtSignature: embeddedThoughtSignature } : {}),
               functionCall: {
                 id: tc.id,
                 name: tc.function.name,
                 args: args,
               },
             });
+
+            if (embeddedThoughtSignature) {
+              embeddedSignatureUsed = true;
+            }
             toolCallIds.push(tc.id);
           }
 
@@ -330,6 +349,7 @@ export function openaiToGeminiCLIRequest(model, body, stream) {
   // Clean schema for tools
   if (gemini.tools?.[0]?.functionDeclarations) {
     for (const fn of gemini.tools[0].functionDeclarations) {
+      fn.name = normalizeAntigravityToolName(fn.name);
       if (fn.parameters) {
         const cleanedSchema = cleanJSONSchemaForAntigravity(fn.parameters);
         fn.parameters = cleanedSchema;
@@ -343,6 +363,20 @@ export function openaiToGeminiCLIRequest(model, body, stream) {
     }
   }
 
+  if (Array.isArray(gemini.contents)) {
+    for (const content of gemini.contents) {
+      if (!Array.isArray(content.parts)) continue;
+      for (const part of content.parts) {
+        if (part.functionCall?.name) {
+          part.functionCall.name = normalizeAntigravityToolName(part.functionCall.name);
+        }
+        if (part.functionResponse?.name) {
+          part.functionResponse.name = normalizeAntigravityToolName(part.functionResponse.name);
+        }
+      }
+    }
+  }
+
   return gemini;
 }
 
diff --git a/open-sse/translator/response/gemini-to-openai.ts b/open-sse/translator/response/gemini-to-openai.ts
index c57ab9299a..e335231dbc 100644
--- a/open-sse/translator/response/gemini-to-openai.ts
+++ b/open-sse/translator/response/gemini-to-openai.ts
@@ -1,5 +1,6 @@
 import { register } from "../registry.ts";
 import { FORMATS } from "../formats.ts";
+import { storeGeminiThoughtSignature } from "../../services/geminiThoughtSignatureStore.ts";
 
 // Convert Gemini response chunk to OpenAI format
 export function geminiToOpenAIResponse(chunk, state) {
@@ -38,6 +39,9 @@ export function geminiToOpenAIResponse(chunk, state) {
     for (const part of content.parts) {
       const hasThoughtSig = part.thoughtSignature || part.thought_signature;
       const isThought = part.thought === true;
+      if (hasThoughtSig && typeof hasThoughtSig === "string") {
+        state.pendingThoughtSignature = hasThoughtSig;
+      }
 
       // Handle thought signature (thinking mode)
       if (hasThoughtSig) {
@@ -75,6 +79,11 @@ export function geminiToOpenAIResponse(chunk, state) {
             },
           };
 
+          if (state.pendingThoughtSignature) {
+            storeGeminiThoughtSignature(toolCall.id, state.pendingThoughtSignature);
+            state.pendingThoughtSignature = null;
+          }
+
           state.toolCalls.set(toolCallIndex, toolCall);
 
           results.push({
@@ -127,6 +136,11 @@ export function geminiToOpenAIResponse(chunk, state) {
           },
         };
 
+        if (state.pendingThoughtSignature) {
+          storeGeminiThoughtSignature(toolCall.id, state.pendingThoughtSignature);
+          state.pendingThoughtSignature = null;
+        }
+
         state.toolCalls.set(toolCallIndex, toolCall);
 
         results.push({
diff --git a/open-sse/utils/cacheControlPolicy.ts b/open-sse/utils/cacheControlPolicy.ts
index 0810674bb1..cd538e2ebf 100644
--- a/open-sse/utils/cacheControlPolicy.ts
+++ b/open-sse/utils/cacheControlPolicy.ts
@@ -148,6 +148,13 @@ export function shouldPreserveCacheControl({
     return false;
   }
 
+  // CC-compatible bridges should default to OmniRoute-managed cache markers.
+  // Their request shape differs from native Claude Messages payloads, so
+  // preserving client markers in auto mode weakens cache coverage.
+  if (typeof targetProvider === "string" && targetProvider.startsWith("anthropic-compatible-cc-")) {
+    return false;
+  }
+
   // Auto mode: use automatic detection (existing logic)
   // Must be a caching-aware client
   if (!isClaudeCodeClient(userAgent)) {
diff --git a/src/app/(dashboard)/dashboard/settings/components/RoutingTab.tsx b/src/app/(dashboard)/dashboard/settings/components/RoutingTab.tsx
index 774552da93..f6b1fe35f7 100644
--- a/src/app/(dashboard)/dashboard/settings/components/RoutingTab.tsx
+++ b/src/app/(dashboard)/dashboard/settings/components/RoutingTab.tsx
@@ -277,7 +277,7 @@ export default function RoutingTab() {
             {
               value: "auto",
               label: "Auto (Recommended)",
-              desc: "Preserve cache_control only for caching-aware clients (Claude Code) with deterministic routing",
+              desc: "Preserve cache_control for native Claude-compatible flows with deterministic routing; CC-compatible bridges use OmniRoute-managed markers",
             },
             {
               value: "always",
diff --git a/src/lib/oauth/providers/claude.ts b/src/lib/oauth/providers/claude.ts
index 9be6e75938..6f3f3eb560 100644
--- a/src/lib/oauth/providers/claude.ts
+++ b/src/lib/oauth/providers/claude.ts
@@ -3,12 +3,12 @@ import { CLAUDE_CONFIG } from "../constants/oauth";
 export const claude = {
   config: CLAUDE_CONFIG,
   flowType: "authorization_code_pkce",
-  buildAuthUrl: (config, redirectUri, state, codeChallenge) => {
+  buildAuthUrl: (config, _redirectUri, state, codeChallenge) => {
     const params = new URLSearchParams({
       code: "true",
       client_id: config.clientId,
       response_type: "code",
-      redirect_uri: redirectUri,
+      redirect_uri: config.redirectUri,
       scope: config.scopes.join(" "),
       code_challenge: codeChallenge,
       code_challenge_method: config.codeChallengeMethod,
@@ -16,7 +16,7 @@ export const claude = {
     });
     return `${config.authorizeUrl}?${params.toString()}`;
   },
-  exchangeToken: async (config, code, redirectUri, codeVerifier, state) => {
+  exchangeToken: async (config, code, _redirectUri, codeVerifier, state) => {
     let authCode = code;
     let codeState = "";
     if (authCode.includes("#")) {
@@ -36,7 +36,7 @@ export const claude = {
         state: codeState || state,
         grant_type: "authorization_code",
         client_id: config.clientId,
-        redirect_uri: redirectUri,
+        redirect_uri: config.redirectUri,
         code_verifier: codeVerifier,
       }),
     });
diff --git a/src/sse/services/auth.ts b/src/sse/services/auth.ts
index 5cd8a8cefb..8f28073265 100644
--- a/src/sse/services/auth.ts
+++ b/src/sse/services/auth.ts
@@ -316,10 +316,13 @@ export { fisherYatesShuffle, getNextFromDeckSync as getNextFromDeck };
  * Resolve provider aliases (e.g., nvidia -> nvidia_nim) for DB lookup
  */
 function getProviderSearchPool(provider: string): string[] {
-  const pool = [provider];
-  if (provider === "nvidia") pool.push("nvidia_nim");
-  if (provider === "nvidia_nim") pool.push("nvidia");
-  return [...new Set(pool)];
+  if (provider === "nvidia") {
+    return ["nvidia", "nvidia_nim"];
+  }
+  if (provider === "nvidia_nim") {
+    return ["nvidia_nim", "nvidia"];
+  }
+  return [provider];
 }
 
 /**
@@ -350,11 +353,10 @@ export async function getProviderCredentials(
 
     // Fix #922: Check for aliases (nvidia/nvidia_nim) to ensure credentials are found
     const providersToSearch = getProviderSearchPool(provider);
-    let connectionsRaw: any[] = [];
-    for (const p of providersToSearch) {
-      const results = await getProviderConnections({ provider: p, isActive: true });
-      if (Array.isArray(results)) connectionsRaw.push(...results);
-    }
+    const connectionResults = await Promise.all(
+      providersToSearch.map((p) => getProviderConnections({ provider: p, isActive: true }))
+    );
+    const connectionsRaw = connectionResults.filter(Array.isArray).flat();
 
     let connections = (Array.isArray(connectionsRaw) ? connectionsRaw : [])
       .map(toProviderConnection)
@@ -371,11 +373,10 @@ export async function getProviderCredentials(
     if (connections.length === 0) {
       // Check all connections (including inactive) to see if rate limited
       // Fix #922: Also search aliases here
-      let allConnectionsRaw: any[] = [];
-      for (const p of providersToSearch) {
-        const results = await getProviderConnections({ provider: p });
-        if (Array.isArray(results)) allConnectionsRaw.push(...results);
-      }
+      const allConnectionsResults = await Promise.all(
+        providersToSearch.map((p) => getProviderConnections({ provider: p }))
+      );
+      const allConnectionsRaw = allConnectionsResults.filter(Array.isArray).flat();
       const allConnections = (Array.isArray(allConnectionsRaw) ? allConnectionsRaw : [])
         .map(toProviderConnection)
         .filter((conn) => conn.id.length > 0);
diff --git a/tests/unit/cache-control-claude-providers.test.mjs b/tests/unit/cache-control-claude-providers.test.mjs
index ae437cdf89..820a1676cd 100644
--- a/tests/unit/cache-control-claude-providers.test.mjs
+++ b/tests/unit/cache-control-claude-providers.test.mjs
@@ -138,4 +138,19 @@ describe("Cache Control Policy - Claude Protocol Providers", () => {
       false
     );
   });
+
+  test("shouldPreserveCacheControl defaults CC-compatible providers to OmniRoute-managed cache in auto mode", () => {
+    const claudeCodeUA = "Claude-Code/1.0.0";
+
+    assert.equal(
+      shouldPreserveCacheControl({
+        userAgent: claudeCodeUA,
+        isCombo: false,
+        targetProvider: "anthropic-compatible-cc-cm",
+        targetFormat: "claude",
+        settings: { alwaysPreserveClientCache: "auto" },
+      }),
+      false
+    );
+  });
 });
diff --git a/tests/unit/cc-compatible-provider.test.mjs b/tests/unit/cc-compatible-provider.test.mjs
index 022668a1e9..4060f825d5 100644
--- a/tests/unit/cc-compatible-provider.test.mjs
+++ b/tests/unit/cc-compatible-provider.test.mjs
@@ -106,7 +106,7 @@ test("buildClaudeCodeCompatibleRequest keeps prior role history while dropping t
   );
   assert.deepEqual(payload.messages[0].content.at(-1).cache_control, { type: "ephemeral" });
   assert.deepEqual(payload.messages[1].content.at(-1).cache_control, { type: "ephemeral" });
-  assert.equal(payload.messages[2].content.at(-1).cache_control, undefined);
+  assert.deepEqual(payload.messages[2].content.at(-1).cache_control, { type: "ephemeral" });
   assert.equal(payload.system.length, 4);
   assert.equal(payload.system.at(-1).text, "sys");
   assert.equal(payload.tools.length, 1);
@@ -182,10 +182,90 @@ test("buildClaudeCodeCompatibleRequest preserves Claude cache markers when reque
     type: "ephemeral",
     ttl: "10m",
   });
-  assert.equal(payload.messages[2].content[0].cache_control, undefined);
+  assert.deepEqual(payload.messages[2].content[0].cache_control, { type: "ephemeral" });
   assert.deepEqual(payload.tools[0].cache_control, { type: "ephemeral", ttl: "30m" });
 });
 
+test("buildClaudeCodeCompatibleRequest supplements missing Claude cache markers in preserve mode", () => {
+  const payload = buildClaudeCodeCompatibleRequest({
+    sourceBody: {
+      max_tokens: 64,
+    },
+    normalizedBody: {
+      max_tokens: 64,
+      messages: [{ role: "user", content: "fallback" }],
+    },
+    claudeBody: {
+      system: [{ type: "text", text: "sys" }],
+      messages: [
+        {
+          role: "user",
+          content: [{ type: "text", text: "u1" }],
+        },
+        {
+          role: "assistant",
+          content: [{ type: "text", text: "a1" }],
+        },
+        { role: "user", content: [{ type: "text", text: "u2" }] },
+      ],
+      tools: [
+        {
+          name: "lookup_weather",
+          description: "Fetch weather",
+          input_schema: {
+            type: "object",
+            properties: {
+              city: { type: "string" },
+            },
+            required: ["city"],
+          },
+        },
+      ],
+    },
+    model: "claude-sonnet-4-6",
+    sessionId: "session-preserve-defaults",
+    preserveCacheControl: true,
+  });
+
+  assert.deepEqual(payload.messages[0].content[0].cache_control, { type: "ephemeral" });
+  assert.deepEqual(payload.messages[1].content[0].cache_control, { type: "ephemeral" });
+  assert.deepEqual(payload.messages[2].content[0].cache_control, { type: "ephemeral" });
+  assert.deepEqual(payload.tools[0].cache_control, { type: "ephemeral", ttl: "1h" });
+});
+
+test("buildClaudeCodeCompatibleRequest marks final user turn and 1h system cache in non-preserve mode", () => {
+  const largeUserPrompt = Array.from(
+    { length: 200 },
+    (_, index) => `Context line ${index + 1}: repeated stable context for cache testing.`
+  ).join("\n");
+
+  const payload = buildClaudeCodeCompatibleRequest({
+    sourceBody: {
+      max_tokens: 64,
+    },
+    normalizedBody: {
+      max_tokens: 64,
+      messages: [
+        { role: "system", content: "Follow the house style exactly." },
+        { role: "user", content: "[Start a new chat]" },
+        { role: "assistant", content: "Hello short ack" },
+        { role: "user", content: largeUserPrompt },
+      ],
+    },
+    model: "claude-sonnet-4-6",
+    sessionId: "session-last-user-cache",
+    preserveCacheControl: false,
+  });
+
+  assert.deepEqual(payload.system.at(-1).cache_control, {
+    type: "ephemeral",
+    ttl: "1h",
+  });
+  assert.deepEqual(payload.messages[0].content[0].cache_control, { type: "ephemeral" });
+  assert.deepEqual(payload.messages[1].content[0].cache_control, { type: "ephemeral" });
+  assert.deepEqual(payload.messages[2].content[0].cache_control, { type: "ephemeral" });
+});
+
 test("buildClaudeCodeCompatibleRequest falls back to a user turn when the source only has assistant/model text", () => {
   const payload = buildClaudeCodeCompatibleRequest({
     sourceBody: {
@@ -419,7 +499,7 @@ test("handleChatCore forces upstream streaming for CC compatible while returning
   assert.equal(payload.usage.completion_tokens, 5);
 });
 
-test("handleChatCore preserves Claude cache_control when CC-compatible requests originate from Claude", async () => {
+test("handleChatCore applies OmniRoute-managed cache strategy for CC-compatible requests in auto mode", async () => {
   const calls = [];
   globalThis.fetch = async (url, init = {}) => {
     calls.push({
@@ -524,18 +604,20 @@ test("handleChatCore preserves Claude cache_control when CC-compatible requests
   assert.equal(calls.length, 1);
   assert.deepEqual(calls[0].body.system.at(-1).cache_control, {
     type: "ephemeral",
-    ttl: "5m",
+    ttl: "1h",
   });
   assert.deepEqual(calls[0].body.messages[0].content[0].cache_control, {
     type: "ephemeral",
   });
   assert.deepEqual(calls[0].body.messages[1].content[0].cache_control, {
     type: "ephemeral",
-    ttl: "10m",
+  });
+  assert.deepEqual(calls[0].body.messages[2].content[0].cache_control, {
+    type: "ephemeral",
   });
   assert.deepEqual(calls[0].body.tools[0].cache_control, {
     type: "ephemeral",
-    ttl: "30m",
+    ttl: "1h",
   });
 });
 
diff --git a/tests/unit/claude-oauth-provider.test.mjs b/tests/unit/claude-oauth-provider.test.mjs
index 479a14429c..6189f60664 100644
--- a/tests/unit/claude-oauth-provider.test.mjs
+++ b/tests/unit/claude-oauth-provider.test.mjs
@@ -10,17 +10,22 @@ test.afterEach(() => {
   globalThis.fetch = originalFetch;
 });
 
-test("Claude OAuth provider uses the runtime redirectUri when building the auth URL", () => {
-  const redirectUri = "http://localhost:43121/callback";
-  const authUrl = claude.buildAuthUrl(CLAUDE_CONFIG, redirectUri, "state-123", "challenge-456");
+test("Claude OAuth provider always uses the configured redirectUri when building the auth URL", () => {
+  const runtimeRedirectUri = "http://localhost:43121/callback";
+  const authUrl = claude.buildAuthUrl(
+    CLAUDE_CONFIG,
+    runtimeRedirectUri,
+    "state-123",
+    "challenge-456"
+  );
   const parsed = new URL(authUrl);
 
-  assert.equal(parsed.searchParams.get("redirect_uri"), redirectUri);
+  assert.equal(parsed.searchParams.get("redirect_uri"), CLAUDE_CONFIG.redirectUri);
   assert.equal(parsed.searchParams.get("state"), "state-123");
   assert.equal(parsed.searchParams.get("code_challenge"), "challenge-456");
 });
 
-test("Claude OAuth provider uses the runtime redirectUri during token exchange", async () => {
+test("Claude OAuth provider always uses the configured redirectUri during token exchange", async () => {
   let captured = null;
 
   globalThis.fetch = async (url, init = {}) => {
@@ -37,18 +42,18 @@ test("Claude OAuth provider uses the runtime redirectUri during token exchange",
     });
   };
 
-  const redirectUri = "http://localhost:43121/callback";
+  const runtimeRedirectUri = "http://localhost:43121/callback";
   await claude.exchangeToken(
     CLAUDE_CONFIG,
     "auth-code#state-from-fragment",
-    redirectUri,
+    runtimeRedirectUri,
     "verifier-123",
     "state-from-request"
   );
 
   assert.equal(captured.url, CLAUDE_CONFIG.tokenUrl);
   assert.equal(captured.method, "POST");
-  assert.equal(captured.body.redirect_uri, redirectUri);
+  assert.equal(captured.body.redirect_uri, CLAUDE_CONFIG.redirectUri);
   assert.equal(captured.body.code, "auth-code");
   assert.equal(captured.body.state, "state-from-fragment");
   assert.equal(captured.body.code_verifier, "verifier-123");
diff --git a/tests/unit/t27-github-copilot-response-format.test.mjs b/tests/unit/t27-github-copilot-response-format.test.mjs
index 83945d9be8..4cc439c24a 100644
--- a/tests/unit/t27-github-copilot-response-format.test.mjs
+++ b/tests/unit/t27-github-copilot-response-format.test.mjs
@@ -1,6 +1,5 @@
 import test from "node:test";
 import assert from "node:assert/strict";
-
 const { GithubExecutor } = await import("../../open-sse/executors/github.ts");
 const { BaseExecutor } = await import("../../open-sse/executors/base.ts");
 
@@ -16,6 +15,16 @@ function streamFromChunks(chunks) {
   });
 }
 
+const originalFetch = globalThis.fetch;
+
+test.afterEach(async () => {
+  globalThis.fetch = originalFetch;
+});
+
+test.after(() => {
+  globalThis.fetch = originalFetch;
+});
+
 test("T27: Claude + response_format=json_object injects system instruction and strips response_format field", () => {
   const executor = new GithubExecutor();
   const request = {
@@ -109,3 +118,103 @@ test("T27: streaming error responses keep their original body readable", async (
     BaseExecutor.prototype.execute = originalExecute;
   }
 });
+
+test("T27: requests use copilotToken from providerSpecificData when available", async () => {
+  globalThis.fetch = async (_url, init = {}) => {
+    assert.equal(init.headers.Authorization, "Bearer copilot_test");
+    return new Response(
+      JSON.stringify({
+        choices: [
+          { index: 0, message: { role: "assistant", content: "OK" }, finish_reason: "stop" },
+        ],
+      }),
+      {
+        status: 200,
+        headers: { "content-type": "application/json" },
+      }
+    );
+  };
+
+  const executor = new GithubExecutor();
+  const result = await executor.execute({
+    model: "gemini-3.1-pro-preview",
+    body: { messages: [{ role: "user", content: "Ping" }], stream: false },
+    stream: false,
+    credentials: {
+      accessToken: "ghu_test",
+      providerSpecificData: {
+        copilotToken: "copilot_test",
+      },
+    },
+  });
+
+  assert.equal(result.response.status, 200);
+  assert.match(await result.response.text(), /OK/);
+});
+
+test("T27: non-stream execute materializes provider responses before returning", async () => {
+  const executor = new GithubExecutor();
+  const originalExecute = BaseExecutor.prototype.execute;
+
+  class WeirdResponse {
+    constructor(body, init = {}) {
+      this._body = body;
+      this.status = init.status || 200;
+      this.statusText = init.statusText || "OK";
+      this.headers = new Headers(init.headers || {});
+      this.bodyUsed = false;
+      this.body = {};
+    }
+
+    async text() {
+      if (this.bodyUsed) {
+        throw new TypeError("Response body is already used");
+      }
+      this.bodyUsed = true;
+      return this._body;
+    }
+  }
+
+  BaseExecutor.prototype.execute = async () => ({
+    response: new WeirdResponse(JSON.stringify({ ok: true }), {
+      status: 200,
+      headers: { "content-type": "application/json" },
+    }),
+    url: "https://api.githubcopilot.com/chat/completions",
+  });
+
+  try {
+    const result = await executor.execute({
+      model: "gemini-3.1-pro-preview",
+      body: { messages: [{ role: "user", content: "Ping" }], stream: false },
+      stream: false,
+      credentials: {
+        accessToken: "ghu_test",
+        providerSpecificData: {
+          copilotToken: "copilot_test",
+        },
+      },
+    });
+
+    assert.equal(result.response.constructor.name, "Response");
+    assert.equal(await result.response.text(), JSON.stringify({ ok: true }));
+  } finally {
+    BaseExecutor.prototype.execute = originalExecute;
+  }
+});
+
+test("T27: needsRefresh respects providerSpecificData copilot token metadata", () => {
+  const executor = new GithubExecutor();
+  const expiresAt = Math.floor(Date.now() / 1000) + 3600;
+
+  assert.equal(
+    executor.needsRefresh({
+      accessToken: "ghu_test",
+      providerSpecificData: {
+        copilotToken: "copilot_test",
+        copilotTokenExpiresAt: expiresAt,
+      },
+    }),
+    false
+  );
+});
diff --git a/tests/unit/t43-gemini-tool-call-no-thought-signature.test.mjs b/tests/unit/t43-gemini-tool-call-no-thought-signature.test.mjs
index 8adc7722b0..af517ad03c 100644
--- a/tests/unit/t43-gemini-tool-call-no-thought-signature.test.mjs
+++ b/tests/unit/t43-gemini-tool-call-no-thought-signature.test.mjs
@@ -1,10 +1,10 @@
 /**
- * T43: Gemini tool call parts must NOT include thoughtSignature.
+ * T43: Gemini tool call parts must preserve thoughtSignature correctly.
  *
  * Regression test for HTTP 400 "invalid argument" when OmniRoute translates
- * OpenAI tool_calls to Gemini format. The thoughtSignature field is only valid
- * on thinking/reasoning parts — injecting it on functionCall parts causes the
- * Gemini API to reject the request with a 400 error.
+ * OpenAI tool_calls to Gemini format. Gemini 3 requires the signature to live on
+ * the first functionCall part for a tool-call batch, and replays fail if the
+ * signature is stripped or emitted as a separate sibling part.
  *
  * Reproduces: https://github.com/diegosouzapw/OmniRoute/issues/725
  */
@@ -24,7 +24,7 @@ function translateToGemini(messages, tools) {
   });
 }
 
-test("T43: functionCall parts must not contain thoughtSignature", () => {
+test("T43: first functionCall part keeps thoughtSignature", () => {
   const messages = [
     { role: "user", content: "What is the weather in Tokyo?" },
     {
@@ -69,19 +69,18 @@ test("T43: functionCall parts must not contain thoughtSignature", () => {
 
   assert.ok(modelTurn, "Expected a model turn with functionCall parts");
 
-  for (const part of modelTurn.parts) {
-    if (part.functionCall) {
-      assert.ok(
-        !("thoughtSignature" in part),
-        `functionCall part must not contain thoughtSignature — Gemini API returns HTTP 400 "invalid argument" when it does. Got: ${JSON.stringify(part)}`
-      );
-      assert.equal(part.functionCall.name, "get_weather");
-      assert.deepEqual(part.functionCall.args, { location: "Tokyo" });
-    }
-  }
+  const functionCallParts = modelTurn.parts.filter((part) => part.functionCall);
+  assert.equal(functionCallParts.length, 1, "Expected exactly 1 functionCall part");
+  assert.equal(functionCallParts[0].functionCall.name, "get_weather");
+  assert.deepEqual(functionCallParts[0].functionCall.args, { location: "Tokyo" });
+  assert.ok(
+    typeof functionCallParts[0].thoughtSignature === "string" &&
+      functionCallParts[0].thoughtSignature.length > 0,
+    `first functionCall part must carry thoughtSignature. Got: ${JSON.stringify(functionCallParts[0])}`
+  );
 });
 
-test("T43: multiple tool calls — none of the functionCall parts may have thoughtSignature", () => {
+test("T43: multiple tool calls only tag the first functionCall part", () => {
   const messages = [
     { role: "user", content: "Get weather for Tokyo and London" },
     {
@@ -122,12 +121,15 @@ test("T43: multiple tool calls — none of the functionCall parts may have thoug
   const functionCallParts = modelTurn.parts.filter((p) => p.functionCall);
   assert.equal(functionCallParts.length, 2, "Expected 2 functionCall parts");
 
-  for (const part of functionCallParts) {
-    assert.ok(
-      !("thoughtSignature" in part),
-      `functionCall part must not contain thoughtSignature. Got: ${JSON.stringify(part)}`
-    );
-  }
+  assert.ok(
+    typeof functionCallParts[0].thoughtSignature === "string" &&
+      functionCallParts[0].thoughtSignature.length > 0,
+    `first functionCall part must carry thoughtSignature. Got: ${JSON.stringify(functionCallParts[0])}`
+  );
+  assert.ok(
+    !("thoughtSignature" in functionCallParts[1]),
+    `parallel follow-up functionCall parts must stay unsigned. Got: ${JSON.stringify(functionCallParts[1])}`
+  );
 });
 
 test("T43: thinking parts still include thoughtSignature (regression guard)", () => {
diff --git a/tests/unit/t44-antigravity-thought-signature-preserved.test.mjs b/tests/unit/t44-antigravity-thought-signature-preserved.test.mjs
new file mode 100644
index 0000000000..db9e6b290a
--- /dev/null
+++ b/tests/unit/t44-antigravity-thought-signature-preserved.test.mjs
@@ -0,0 +1,73 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+
+import { AntigravityExecutor } from "../../open-sse/executors/antigravity.ts";
+
+test("T44: Antigravity preserves thoughtSignature for functionCall turns", () => {
+  const executor = new AntigravityExecutor();
+  const transformed = executor.transformRequest(
+    "gemini-3-flash",
+    {
+      request: {
+        contents: [
+          {
+            role: "model",
+            parts: [
+              { thought: true, text: "internal reasoning" },
+              { thoughtSignature: "sig_123" },
+              {
+                functionCall: {
+                  id: "call_1",
+                  name: "default_api:memos_load_user_memory",
+                  args: { userId: "u1" },
+                },
+              },
+            ],
+          },
+        ],
+        tools: [{ functionDeclarations: [{ name: "default_api:memos_load_user_memory" }] }],
+      },
+    },
+    true,
+    { projectId: "test-project" }
+  );
+
+  const parts = transformed.request.contents[0].parts;
+
+  assert.equal(
+    parts.some((part) => part.thought === true),
+    false,
+    "thought text should still be stripped before sending to Antigravity"
+  );
+  assert.equal(
+    parts.some((part) => part.thoughtSignature === "sig_123"),
+    true,
+    "tool-call turns must keep thoughtSignature for Gemini 3+ compatibility"
+  );
+  assert.equal(
+    parts.some((part) => part.functionCall?.name === "default_api:memos_load_user_memory"),
+    true,
+    "functionCall must still be present"
+  );
+});
+
+test("T44: Antigravity still strips standalone thoughtSignature without tool calls", () => {
+  const executor = new AntigravityExecutor();
+  const transformed = executor.transformRequest(
+    "gemini-3-flash",
+    {
+      request: {
+        contents: [
+          {
+            role: "model",
+            parts: [{ thoughtSignature: "sig_123" }, { text: "plain text" }],
+          },
+        ],
+      },
+    },
+    true,
+    { projectId: "test-project" }
+  );
+
+  assert.deepEqual(transformed.request.contents[0].parts, [{ text: "plain text" }]);
+});