chore: remove dead sanitizeThinkingSignatures field from transcript policy (#99880)

* chore: remove dead sanitizeThinkingSignatures field from transcript policy

The sanitizeThinkingSignatures field on TranscriptPolicy and
AgentRuntimeTranscriptPolicy was orphaned when the google-antigravity
provider was removed in 382fe8009a. That commit deleted the only
consumer (sanitizeSessionHistory in google.ts) but left the field
declaration in both types and the default value, plus stale
references across test fixtures.

Remove the field from:
- TranscriptPolicy type and DEFAULT_TRANSCRIPT_POLICY (transcript-policy.ts)
- AgentRuntimeTranscriptPolicy (runtime-plan/types.ts)
- All test/mock/compact-harness references (14 sites)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* chore: remove blank lines from transcript policy cleanup

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Co-authored-by: Colin <colin@solvely.net>

src/agents/embedded-agent-runner.sanitize-session-history.test.ts

@@ -1013,7 +1013,6 @@ describe("sanitizeSessionHistory", () => {
           preserveNativeAnthropicToolUseIds: false,
           repairToolUseResultPairing: false,
           preserveSignatures: false,
-          sanitizeThinkingSignatures: false,
           dropThinkingBlocks: false,
           dropReasoningFromHistory: false,
           applyGoogleTurnOrdering: false,
@@ -1472,7 +1471,6 @@ describe("sanitizeSessionHistory", () => {
       preserveNativeAnthropicToolUseIds: true,
       repairToolUseResultPairing: true,
       preserveSignatures: true,
-      sanitizeThinkingSignatures: false,
       dropThinkingBlocks: false,
       dropReasoningFromHistory: false,
       applyGoogleTurnOrdering: false,
@@ -2137,7 +2135,6 @@ describe("sanitizeSessionHistory", () => {
         repairToolUseResultPairing: true,
         preserveSignatures: true,
         sanitizeThoughtSignatures: undefined,
-        sanitizeThinkingSignatures: false,
         dropThinkingBlocks: false,
         applyGoogleTurnOrdering: false,
         validateGeminiTurns: false,
@@ -2273,7 +2270,6 @@ describe("sanitizeSessionHistory", () => {
           preserveNativeAnthropicToolUseIds: false,
           repairToolUseResultPairing: true,
           preserveSignatures: false,
-          sanitizeThinkingSignatures: false,
           dropThinkingBlocks: false,
           applyGoogleTurnOrdering: false,
           validateGeminiTurns: false,
@@ -2488,7 +2484,6 @@ describe("sanitizeSessionHistory", () => {
       repairToolUseResultPairing: true,
       preserveSignatures: true,
       sanitizeThoughtSignatures: undefined,
-      sanitizeThinkingSignatures: false,
       dropThinkingBlocks: true,
       applyGoogleTurnOrdering: false,
       validateGeminiTurns: false,
@@ -2609,7 +2604,6 @@ describe("sanitizeSessionHistory", () => {
         preserveNativeAnthropicToolUseIds: false,
         repairToolUseResultPairing: true,
         preserveSignatures: false,
-        sanitizeThinkingSignatures: false,
         dropThinkingBlocks: false,
         applyGoogleTurnOrdering: false,
         validateGeminiTurns: false,
@@ -2659,7 +2653,6 @@ describe("sanitizeSessionHistory", () => {
         preserveNativeAnthropicToolUseIds: false,
         repairToolUseResultPairing: true,
         preserveSignatures: false,
-        sanitizeThinkingSignatures: false,
         dropThinkingBlocks: false,
         dropReasoningFromHistory: false,
         applyGoogleTurnOrdering: false,
@@ -2702,7 +2695,6 @@ describe("sanitizeSessionHistory", () => {
         preserveNativeAnthropicToolUseIds: false,
         repairToolUseResultPairing: true,
         preserveSignatures: false,
-        sanitizeThinkingSignatures: false,
         dropThinkingBlocks: false,
         dropReasoningFromHistory: false,
         applyGoogleTurnOrdering: false,
@@ -2744,7 +2736,6 @@ describe("sanitizeSessionHistory", () => {
         preserveNativeAnthropicToolUseIds: false,
         repairToolUseResultPairing: true,
         preserveSignatures: false,
-        sanitizeThinkingSignatures: false,
         dropThinkingBlocks: false,
         applyGoogleTurnOrdering: false,
         validateGeminiTurns: false,

src/agents/embedded-agent-runner/compact.hooks.harness.ts

@@ -303,7 +303,6 @@ function createCompactHooksRuntimePlan(params: BuildAgentRuntimePlanParams): Age
     preserveNativeAnthropicToolUseIds: false,
     repairToolUseResultPairing: false,
     preserveSignatures: false,
-    sanitizeThinkingSignatures: false,
     dropThinkingBlocks: false,
     applyGoogleTurnOrdering: false,
     validateGeminiTurns: false,

src/agents/embedded-agent-runner/run.overflow-compaction.test.ts

@@ -141,7 +141,6 @@ function makeForwardedRuntimePlan(overrides: RuntimePlanOverrides = {}): AgentRu
     preserveNativeAnthropicToolUseIds: false,
     repairToolUseResultPairing: true,
     preserveSignatures: false,
-    sanitizeThinkingSignatures: true,
     dropThinkingBlocks: false,
     applyGoogleTurnOrdering: false,
     validateGeminiTurns: false,

src/agents/embedded-agent-runner/run/attempt.spawn-workspace.context-engine.test.ts

@@ -737,7 +737,6 @@ describe("runEmbeddedAttempt context engine sessionKey forwarding", () => {
               preserveNativeAnthropicToolUseIds: false,
               repairToolUseResultPairing: true,
               preserveSignatures: true,
-              sanitizeThinkingSignatures: false,
               dropThinkingBlocks: false,
               dropReasoningFromHistory: false,
               applyGoogleTurnOrdering: false,

src/agents/embedded-agent-runner/run/attempt.transcript-policy.test.ts

@@ -26,7 +26,6 @@ describe("resolveAttemptTranscriptPolicy", () => {
       preserveNativeAnthropicToolUseIds: false,
       repairToolUseResultPairing: true,
       preserveSignatures: true,
-      sanitizeThinkingSignatures: false,
       dropThinkingBlocks: true,
       applyGoogleTurnOrdering: false,
       validateGeminiTurns: false,

src/agents/runtime-plan/types.ts

@@ -361,7 +361,6 @@ export type AgentRuntimeTranscriptPolicy = {
     allowBase64Only?: boolean;
     includeCamelCase?: boolean;
   };
-  sanitizeThinkingSignatures: boolean;
   dropThinkingBlocks: boolean;
   dropReasoningFromHistory?: boolean;
   applyGoogleTurnOrdering: boolean;

src/agents/test-helpers/embedded-agent-runner-e2e-mocks.ts

@@ -116,7 +116,6 @@ export function installEmbeddedRunnerFastRunE2eMocks(
             preserveNativeAnthropicToolUseIds: false,
             repairToolUseResultPairing: true,
             preserveSignatures: false,
-            sanitizeThinkingSignatures: true,
             dropThinkingBlocks: false,
             applyGoogleTurnOrdering: false,
             validateGeminiTurns: false,

src/agents/transcript-policy.ts

@@ -31,7 +31,6 @@ export type TranscriptPolicy = {
     allowBase64Only?: boolean;
     includeCamelCase?: boolean;
   };
-  sanitizeThinkingSignatures: boolean;
   dropThinkingBlocks: boolean;
   dropReasoningFromHistory?: boolean;
   applyGoogleTurnOrdering: boolean;
@@ -75,7 +74,6 @@ const DEFAULT_TRANSCRIPT_POLICY: TranscriptPolicy = {
   repairToolUseResultPairing: true,
   preserveSignatures: false,
   sanitizeThoughtSignatures: undefined,
-  sanitizeThinkingSignatures: false,
   dropThinkingBlocks: false,
   dropReasoningFromHistory: false,
   applyGoogleTurnOrdering: false,