diff --git a/src/server/ToolResultDelivery.ts b/src/server/ToolResultDelivery.ts
index 66d173893d..625c41feec 100644
--- a/src/server/ToolResultDelivery.ts
+++ b/src/server/ToolResultDelivery.ts
@@ -2,7 +2,8 @@ import type { CallToolResult } from "@modelcontextprotocol/server";
 import { STDIO_DEFAULT_MAX_BUFFER_SIZE } from "@modelcontextprotocol/server";
 
 import type { ToolContract } from "../contracts/toolContractTypes.js";
-import type { Evidence } from "../domain/evidence.js";
+import type { EvidenceWriter } from "../application/investigation/InvestigationRecordPort.js";
+import { evidenceSchema, type Evidence } from "../domain/evidence.js";
 import {
   projectAnalysisError,
   type AnalysisErrorProjection,
@@ -146,13 +147,17 @@ export class ToolResultDelivery {
     );
   }
 
-  /** Deliver the original failure with the producer-acknowledged partial Evidence reference. */
-  toRecordedPartialErrorToolResult(
+  /** Retain valid partial Evidence and reference it only after recording succeeds. */
+  toPartialErrorToolResult(
     error: AnalysisError,
-    evidenceId: string,
-    recorded: Result<unknown, AnalysisError>,
     targetContent: boolean,
+    recordEvidence?: EvidenceWriter["recordEvidence"],
   ): CallToolResult {
+    if (recordEvidence === undefined)
+      return this.toErrorToolResult(error, targetContent);
+    const partial = evidenceSchema.safeParse(error.partialObservation);
+    if (!partial.success) return this.toErrorToolResult(error, targetContent);
+    const recorded = recordEvidence(partial.data);
     if (!recorded.ok) return this.toErrorToolResult(error, targetContent);
     const projected = projectAnalysisError(error);
     return this.projectedErrorResult(
@@ -162,7 +167,7 @@ export class ToolResultDelivery {
           ...projected.details,
           partial_observation: {
             kind: "retained-evidence",
-            evidence_id: evidenceId,
+            evidence_id: partial.data.evidence_id,
           },
         },
       },
diff --git a/src/server/contractToolHandler.ts b/src/server/contractToolHandler.ts
index 592139a3c7..1c2690863c 100644
--- a/src/server/contractToolHandler.ts
+++ b/src/server/contractToolHandler.ts
@@ -31,24 +31,12 @@ export const deliverEvidenceResult = (
   contract: ToolContract,
   recordEvidence?: EvidenceWriter["recordEvidence"],
 ): CallToolResult => {
-  if (!result.ok) {
-    const partial = result.error.partialObservation;
-    if (
-      partial !== undefined &&
-      "evidence_id" in partial &&
-      typeof partial.evidence_id === "string"
-    ) {
-      const recorded = recordEvidence?.(partial);
-      if (recorded !== undefined)
-        return server.delivery.toRecordedPartialErrorToolResult(
-          result.error,
-          partial.evidence_id,
-          recorded,
-          contract.returnsTargetContent,
-        );
-    }
-    return server.delivery.toCallToolResult(result, contract);
-  }
+  if (!result.ok)
+    return server.delivery.toPartialErrorToolResult(
+      result.error,
+      contract.returnsTargetContent,
+      recordEvidence,
+    );
   const recorded = recordEvidence?.(result.value);
   return server.delivery.toEvidenceToolResult(result.value, contract, recorded);
 };
diff --git a/src/server/registerCutterTools.ts b/src/server/registerCutterTools.ts
index 527a4db747..54ff0e4c93 100644
--- a/src/server/registerCutterTools.ts
+++ b/src/server/registerCutterTools.ts
@@ -4,7 +4,6 @@ import type { Logger } from "pino";
 import type { CutterBridgeService } from "../cutter/CutterBridgeService.js";
 import type { EvidenceWriter } from "../application/investigation/InvestigationRecordPort.js";
 import { toolContract } from "../contracts/toolContracts.js";
-import { evidenceSchema } from "../domain/evidence.js";
 import {
   runWithExternalMutationAdmission,
   type ExternalMutationAdmission,
@@ -56,22 +55,12 @@ export const registerCutterTools = (
         (value) => value,
         () => service.retryCleanup(),
       );
-      if (!result.ok) {
-        const partial = evidenceSchema.safeParse(
-          result.error.partialObservation,
+      if (!result.ok)
+        return delivery.toPartialErrorToolResult(
+          result.error,
+          command.returnsTargetContent,
+          recordEvidence,
         );
-        if (partial.success) {
-          const recorded = recordEvidence?.(partial.data);
-          if (recorded !== undefined)
-            return delivery.toRecordedPartialErrorToolResult(
-              result.error,
-              partial.data.evidence_id,
-              recorded,
-              command.returnsTargetContent,
-            );
-        }
-        return delivery.toCallToolResult(result, command);
-      }
       return delivery.toEvidenceToolResult(
         result.value,
         command,
diff --git a/src/server/registerFridaTools.ts b/src/server/registerFridaTools.ts
index 0d9218694a..b5966a3eb8 100644
--- a/src/server/registerFridaTools.ts
+++ b/src/server/registerFridaTools.ts
@@ -7,9 +7,6 @@ import { FridaInstrumentationService } from "../application/frida/FridaInstrumen
 import type { FridaInstrumentationPort } from "../application/frida/FridaInstrumentationPort.js";
 import type { FridaRemoteConnection } from "../application/frida/FridaInstrumentationPort.js";
 import { toolContract } from "../contracts/toolContracts.js";
-import type { ToolContract } from "../contracts/toolContractTypes.js";
-import { evidenceSchema } from "../domain/evidence.js";
-import type { AnalysisError } from "../domain/analysisErrorBase.js";
 import { AnalysisInputError } from "../domain/analysisErrorCore.js";
 import { jsonValueSchema } from "../domain/jsonValue.js";
 import { logToolExecution } from "./toolLogging.js";
@@ -96,14 +93,12 @@ export const registerFridaTools = (
                 error: new AnalysisInputError(start.name),
               }),
       );
-      if (!result.ok) {
-        return deliverPartialEvidenceError(
-          result,
-          start,
-          delivery,
+      if (!result.ok)
+        return delivery.toPartialErrorToolResult(
+          result.error,
+          start.returnsTargetContent,
           recordEvidence,
         );
-      }
       return delivery.toCallToolResult(
         {
           ok: true,
@@ -141,14 +136,12 @@ export const registerFridaTools = (
                 error: new AnalysisInputError(load.name),
               }),
       );
-      if (!result.ok) {
-        return deliverPartialEvidenceError(
-          result,
-          load,
-          delivery,
+      if (!result.ok)
+        return delivery.toPartialErrorToolResult(
+          result.error,
+          load.returnsTargetContent,
           recordEvidence,
         );
-      }
       return delivery.toEvidenceToolResult(
         result.value,
         load,
@@ -274,14 +267,12 @@ export const registerFridaTools = (
         instrument.name,
         () => operation,
       );
-      if (!result.ok) {
-        return deliverPartialEvidenceError(
-          result,
-          instrument,
-          delivery,
+      if (!result.ok)
+        return delivery.toPartialErrorToolResult(
+          result.error,
+          instrument.returnsTargetContent,
           recordEvidence,
         );
-      }
       return delivery.toEvidenceToolResult(
         result.value.evidence,
         instrument,
@@ -291,23 +282,6 @@ export const registerFridaTools = (
   );
 };
 
-const deliverPartialEvidenceError = (
-  result: { readonly ok: false; readonly error: AnalysisError },
-  contract: ToolContract,
-  delivery: ToolResultDelivery,
-  recordEvidence: EvidenceWriter["recordEvidence"] | undefined,
-): ReturnType<ToolResultDelivery["toCallToolResult"]> => {
-  const parsed = evidenceSchema.safeParse(result.error.partialObservation);
-  if (!parsed.success || recordEvidence === undefined)
-    return delivery.toCallToolResult(result, contract);
-  return delivery.toRecordedPartialErrorToolResult(
-    result.error,
-    parsed.data.evidence_id,
-    recordEvidence(parsed.data),
-    contract.returnsTargetContent,
-  );
-};
-
 const remoteConnection = (
   input:
     | {
diff --git a/src/server/registerGdbTools.ts b/src/server/registerGdbTools.ts
index 6ce117ef5c..bc488a5f12 100644
--- a/src/server/registerGdbTools.ts
+++ b/src/server/registerGdbTools.ts
@@ -9,7 +9,6 @@ import {
   summarizeRetainedAnalysis,
 } from "../application/analysisView/AnalysisViewService.js";
 import { toolContract } from "../contracts/toolContracts.js";
-import { evidenceSchema } from "../domain/evidence.js";
 import { err, ok } from "../domain/result.js";
 import { AnalysisInputError } from "../domain/analysisErrorCore.js";
 import {
@@ -57,19 +56,11 @@ export const registerGdbTools = (
           { ok: true, value: result.value },
           start,
         );
-      const partial = result.error.partialObservation;
-      const parsed = evidenceSchema.safeParse(partial);
-      if (parsed.success) {
-        const recorded = recordEvidence?.(parsed.data);
-        if (recorded !== undefined)
-          return delivery.toRecordedPartialErrorToolResult(
-            result.error,
-            parsed.data.evidence_id,
-            recorded,
-            start.returnsTargetContent,
-          );
-      }
-      return delivery.toCallToolResult(result, start);
+      return delivery.toPartialErrorToolResult(
+        result.error,
+        start.returnsTargetContent,
+        recordEvidence,
+      );
     },
   );
   server.registerTool(
@@ -105,21 +96,12 @@ export const registerGdbTools = (
         : input.detail === "summary"
           ? summarizeRetainedAnalysis(executed.value.evidence, retention)
           : ok(executed.value.evidence);
-      if (!result.ok) {
-        const partial = result.error.partialObservation;
-        const parsed = evidenceSchema.safeParse(partial);
-        if (parsed.success) {
-          const recorded = recordEvidence?.(parsed.data);
-          if (recorded !== undefined)
-            return delivery.toRecordedPartialErrorToolResult(
-              result.error,
-              parsed.data.evidence_id,
-              recorded,
-              consoleContract.returnsTargetContent,
-            );
-        }
-        return delivery.toCallToolResult(result, consoleContract);
-      }
+      if (!result.ok)
+        return delivery.toPartialErrorToolResult(
+          result.error,
+          consoleContract.returnsTargetContent,
+          recordEvidence,
+        );
       const recorded = recordEvidence?.(result.value);
       return delivery.toEvidenceToolResult(
         result.value,
diff --git a/src/server/registerReverseEngineeringTools.ts b/src/server/registerReverseEngineeringTools.ts
index f2b0540244..1860d68fd7 100644
--- a/src/server/registerReverseEngineeringTools.ts
+++ b/src/server/registerReverseEngineeringTools.ts
@@ -12,7 +12,6 @@ import {
 } from "../application/reverse/ReverseEngineeringService.js";
 import type { EvidenceLookup } from "../application/EvidenceInputResolver.js";
 import type { EvidenceWriter } from "../application/investigation/InvestigationRecordPort.js";
-import type { Evidence } from "../domain/evidence.js";
 import { toolContract } from "../contracts/toolContracts.js";
 import type { ToolContract } from "../contracts/toolContractTypes.js";
 import { logToolExecution } from "./toolLogging.js";
@@ -65,10 +64,9 @@ export const registerReverseEngineeringTools = (
             ),
           );
           if (!result.ok)
-            return deliverFailure(
+            return delivery.toPartialErrorToolResult(
               result.error,
-              objdump,
-              delivery,
+              objdump.returnsTargetContent,
               recordEvidence,
             );
           return delivery.toEvidenceToolResult(
@@ -87,7 +85,11 @@ export const registerReverseEngineeringTools = (
       if (parsed.ok && withAdmittedExternalMutation !== undefined) {
         const cleanup = await service.retryCleanup(rizin.name);
         if (!cleanup.ok)
-          return deliverFailure(cleanup.error, rizin, delivery, recordEvidence);
+          return delivery.toPartialErrorToolResult(
+            cleanup.error,
+            rizin.returnsTargetContent,
+            recordEvidence,
+          );
         const admitted = await withAdmittedExternalMutation(
           parsed.value.path,
           context.mcpReq.signal,
@@ -124,15 +126,18 @@ export const registerReverseEngineeringTools = (
           },
         );
         if (!admitted.ok)
-          return deliverFailure(
+          return delivery.toPartialErrorToolResult(
             admitted.error,
-            rizin,
-            delivery,
+            rizin.returnsTargetContent,
             recordEvidence,
           );
         const result = admitted.value;
         if (!result.ok)
-          return deliverFailure(result.error, rizin, delivery, recordEvidence);
+          return delivery.toPartialErrorToolResult(
+            result.error,
+            rizin.returnsTargetContent,
+            recordEvidence,
+          );
         return delivery.toEvidenceToolResult(
           result.value,
           rizin,
@@ -155,10 +160,9 @@ export const registerReverseEngineeringTools = (
               : Promise.resolve(parsed),
           );
           if (!result.ok)
-            return deliverFailure(
+            return delivery.toPartialErrorToolResult(
               result.error,
-              rizin,
-              delivery,
+              rizin.returnsTargetContent,
               recordEvidence,
             );
           return delivery.toEvidenceToolResult(
@@ -189,26 +193,3 @@ const runAdmitted = async (
     ? admitted.value
     : delivery.toErrorToolResult(admitted.error, contract.returnsTargetContent);
 };
-
-const deliverFailure = (
-  error: import("../domain/analysisErrorBase.js").AnalysisError,
-  contract: ToolContract,
-  delivery: ToolResultDelivery,
-  recordEvidence?: EvidenceWriter["recordEvidence"],
-) => {
-  const partial = error.partialObservation;
-  if (isEvidence(partial) && recordEvidence !== undefined)
-    return delivery.toRecordedPartialErrorToolResult(
-      error,
-      partial.evidence_id,
-      recordEvidence(partial),
-      contract.returnsTargetContent,
-    );
-  return delivery.toErrorToolResult(error, contract.returnsTargetContent);
-};
-
-const isEvidence = (value: unknown): value is Evidence =>
-  typeof value === "object" &&
-  value !== null &&
-  "evidence_id" in value &&
-  typeof value.evidence_id === "string";
diff --git a/src/server/registerRizinDebugTools.ts b/src/server/registerRizinDebugTools.ts
index 1c6b2b8a69..8d2fd334b1 100644
--- a/src/server/registerRizinDebugTools.ts
+++ b/src/server/registerRizinDebugTools.ts
@@ -5,7 +5,6 @@ import type { EvidenceWriter } from "../application/investigation/InvestigationR
 import { toolContract } from "../contracts/toolContracts.js";
 import { AnalysisInputError } from "../domain/analysisErrorCore.js";
 import type { RizinDebugSessionManager } from "../rizin/RizinDebugSessionManager.js";
-import { evidenceSchema } from "../domain/evidence.js";
 import {
   runOwnedCleanupWithExternalMutationAdmission,
   runWithExternalMutationAdmission,
@@ -82,22 +81,12 @@ export const registerRizinDebugTools = (
         (value) => value.evidence,
         () => manager.retryCleanupFailures(),
       );
-      if (!result.ok) {
-        const partial = evidenceSchema.safeParse(
-          result.error.partialObservation,
+      if (!result.ok)
+        return delivery.toPartialErrorToolResult(
+          result.error,
+          command.returnsTargetContent,
+          recordEvidence,
         );
-        if (partial.success) {
-          const recorded = recordEvidence?.(partial.data);
-          if (recorded !== undefined)
-            return delivery.toRecordedPartialErrorToolResult(
-              result.error,
-              partial.data.evidence_id,
-              recorded,
-              command.returnsTargetContent,
-            );
-        }
-        return delivery.toCallToolResult(result, command);
-      }
       return delivery.toEvidenceToolResult(
         result.value.evidence,
         command,
diff --git a/tests/boundary/mcp/androidLateCompletionMcp.test.ts b/tests/boundary/mcp/androidLateCompletionMcp.test.ts
index 36eaf8fece..6dcb2f67f3 100644
--- a/tests/boundary/mcp/androidLateCompletionMcp.test.ts
+++ b/tests/boundary/mcp/androidLateCompletionMcp.test.ts
@@ -73,12 +73,12 @@ it("retains completed Android Evidence through the MCP cancellation delivery pat
   expect(controlReply.isError).not.toBe(true);
   const control = parseEvidence(controlReply.structuredContent);
   const delivered = createDeferred<CallToolResult>();
-  const deliver = server.delivery.toRecordedPartialErrorToolResult.bind(
+  const deliver = server.delivery.toPartialErrorToolResult.bind(
     server.delivery,
   );
   vi.spyOn(
     ToolResultDelivery.prototype,
-    "toRecordedPartialErrorToolResult",
+    "toPartialErrorToolResult",
   ).mockImplementation((...args) => {
     const result = deliver(...args);
     delivered.resolve(result);
diff --git a/tests/boundary/mcp/contractToolHandlerTargetContent.test.ts b/tests/boundary/mcp/contractToolHandlerTargetContent.test.ts
index 9e8a9d24b0..21c28d46ed 100644
--- a/tests/boundary/mcp/contractToolHandlerTargetContent.test.ts
+++ b/tests/boundary/mcp/contractToolHandlerTargetContent.test.ts
@@ -1,4 +1,4 @@
-import { describe, expect, it } from "vitest";
+import { describe, expect, it, vi } from "vitest";
 
 import type {
   CallToolResult,
@@ -10,11 +10,14 @@ import { toolContract } from "../../../src/contracts/toolContracts.js";
 import { AnalysisCancelledError } from "../../../src/domain/analysisErrorCore.js";
 import { createEvidence } from "../../../src/domain/evidence.js";
 import type { Evidence } from "../../../src/domain/evidence.js";
+import { projectAnalysisError } from "../../../src/domain/analysisErrorProjection.js";
+import type { FridaDeviceList } from "../../../src/domain/fridaDiscovery.js";
 import { err, ok } from "../../../src/domain/result.js";
 import { silentLogger } from "../../../src/logger.js";
 import { createEvidenceToolHandler } from "../../../src/server/contractToolHandler.js";
 import { EvidenceMcpServer } from "../../../src/server/EvidenceMcpServer.js";
 import { ToolResultDelivery } from "../../../src/server/toolResult.js";
+import { parseMcpToolError } from "../../fixtures/mcpToolError.js";
 
 const UNTRUSTED_TARGET_CONTENT = {
   provenance: { untrusted_content: true, source: "analysis_target" },
@@ -68,6 +71,48 @@ const deliverPartialFailure = async (): Promise<{
 };
 
 describe("shared Evidence handler target-content framing", () => {
+  it("keeps a non-Evidence partial with a caller-selected evidence_id inline without recording it", async () => {
+    const partial = {
+      devices: [],
+      cleanup_error: null,
+      evidence_id: "caller-selected",
+    };
+    const observation: FridaDeviceList = partial;
+    const reason = { request: "cancel capture" };
+    const failure = new AnalysisCancelledError("inspect_packet_capture", {
+      cause: reason,
+      partialObservation: observation,
+    });
+    const recordEvidence = vi.fn(() => ok("added" as const));
+    const server = new EvidenceMcpServer(
+      { name: "inline-partial-error-test", version: "1" },
+      { capabilities: {} },
+      recordEvidence,
+      new ToolResultDelivery(STDIO_DEFAULT_MAX_BUFFER_SIZE),
+    );
+    const contract = toolContract("inspect_packet_capture");
+    const handler = createEvidenceToolHandler(
+      server,
+      async () => err(failure),
+      silentLogger,
+      recordEvidence,
+    );
+
+    const result = await handler(contract)({ path: "recording.pcap" }, context);
+    const projected = parseMcpToolError(result);
+    expect(projected.error).toMatchObject({
+      code: "cancelled",
+      message: projectAnalysisError(failure).message,
+      details: { operation: "inspect_packet_capture" },
+    });
+    expect(projected.error.details?.partial_observation).toEqual(partial);
+    expect(result.structuredContent).toEqual(projected);
+    expect(recordEvidence).not.toHaveBeenCalled();
+    expect(failure.cause).toBe(reason);
+    expect(failure.partialObservation).toBe(partial);
+    expect(result._meta).toEqual(UNTRUSTED_TARGET_CONTENT);
+  });
+
   it("marks a retained partial-observation error as untrusted target content", async () => {
     const { result, evidence } = await deliverPartialFailure();
     expect(result.isError).toBe(true);
diff --git a/tests/boundary/mcp/fridaLifecycleMcp.test.ts b/tests/boundary/mcp/fridaLifecycleMcp.test.ts
index 04946fded8..f28c2f6793 100644
--- a/tests/boundary/mcp/fridaLifecycleMcp.test.ts
+++ b/tests/boundary/mcp/fridaLifecycleMcp.test.ts
@@ -384,7 +384,7 @@ it.each([
     );
     const partial = vi.spyOn(
       ToolResultDelivery.prototype,
-      "toRecordedPartialErrorToolResult",
+      "toPartialErrorToolResult",
     );
     onTestFinished(() => {
       loadSpy.mockRestore();
@@ -526,7 +526,7 @@ it("preserves the native resume failure after MCP cancellation reaches the serve
     fixture.controls.resume = async () => {};
     throw new Error("native resume rejected");
   };
-  const delivery = vi.spyOn(ToolResultDelivery.prototype, "toCallToolResult");
+  const delivery = vi.spyOn(ToolResultDelivery.prototype, "toErrorToolResult");
   onTestFinished(() => delivery.mockRestore());
   let serverSignal: AbortSignal | undefined;
   const resume = fixture.manager.resumeSession.bind(fixture.manager);
@@ -562,12 +562,9 @@ it("preserves the native resume failure after MCP cancellation reaches the serve
   await pending;
   await vi.waitFor(() => expect(delivery).toHaveBeenCalledOnce());
   expect(delivery.mock.calls[0]?.[0]).toMatchObject({
-    ok: false,
-    error: {
-      _tag: "AnalysisCapabilityUnavailableError",
-      operation: "resume_frida_session",
-      message: expect.stringContaining("native resume rejected"),
-    },
+    _tag: "AnalysisCapabilityUnavailableError",
+    operation: "resume_frida_session",
+    message: expect.stringContaining("native resume rejected"),
   });
   expect(fixture.controls.detachCalls).toBe(1);
   expect(fixture.unloaded).toEqual(["resume-failure"]);
diff --git a/tests/boundary/mcp/reverseEngineeringPartialMcp.test.ts b/tests/boundary/mcp/reverseEngineeringPartialMcp.test.ts
index 28ffe79402..2fb8c4af2d 100644
--- a/tests/boundary/mcp/reverseEngineeringPartialMcp.test.ts
+++ b/tests/boundary/mcp/reverseEngineeringPartialMcp.test.ts
@@ -7,7 +7,12 @@ import { dirname, join } from "node:path";
 import { expect, it, vi } from "vitest";
 
 import { TestReverseEngineeringService as ReverseEngineeringService } from "../../support/reverseEngineeringService.js";
-import { AnalysisInputError } from "../../../src/domain/analysisErrorCore.js";
+import {
+  AnalysisCancelledError,
+  AnalysisInputError,
+} from "../../../src/domain/analysisErrorCore.js";
+import { projectAnalysisError } from "../../../src/domain/analysisErrorProjection.js";
+import type { FridaDeviceList } from "../../../src/domain/fridaDiscovery.js";
 import {
   createBinarySessionTargets,
   createCacheProvider,
@@ -37,6 +42,50 @@ const createTimedOutRizinService = (): ReverseEngineeringService =>
     },
   });
 
+it("keeps a non-Evidence partial with a caller-selected evidence_id inline in a reverse tool error", async () => {
+  const { server, handler } = createReverseEngineeringMcpHarness();
+  const partial = {
+    devices: [],
+    cleanup_error: null,
+    evidence_id: "caller-selected",
+  };
+  const observation: FridaDeviceList = partial;
+  const reason = { request: "cancel inspection" };
+  const failure = new AnalysisCancelledError("inspect_with_objdump", {
+    cause: reason,
+    partialObservation: observation,
+  });
+  const service = new ReverseEngineeringService();
+  vi.spyOn(service, "inspectWithObjdump").mockResolvedValue(err(failure));
+  const recordEvidence = vi.fn(() => ok("added" as const));
+  registerReverseEngineeringTools(
+    server,
+    service,
+    pino({ enabled: false }),
+    createToolResultDelivery(2 * 1024 * 1024),
+    recordEvidence,
+  );
+
+  const result = (await invokeWithLiveSignal(handler("inspect_with_objdump"), {
+    path: "package.json",
+    operation: "file_headers",
+  })) as CallToolResult;
+  const projected = parseMcpToolError(result);
+  expect(projected.error).toMatchObject({
+    code: "cancelled",
+    message: projectAnalysisError(failure).message,
+    details: { operation: "inspect_with_objdump" },
+  });
+  expect(projected.error.details?.partial_observation).toEqual(partial);
+  expect(result.structuredContent).toEqual(projected);
+  expect(recordEvidence).not.toHaveBeenCalled();
+  expect(failure.cause).toBe(reason);
+  expect(failure.partialObservation).toBe(partial);
+  expect(result._meta).toEqual({
+    provenance: { untrusted_content: true, source: "analysis_target" },
+  });
+});
+
 it("records partial Evidence and references it in the original MCP error", async () => {
   const { server, handler } = createReverseEngineeringMcpHarness();
   const service = createTimedOutRizinService();
diff --git a/tests/boundary/mcp/toolResult.test.ts b/tests/boundary/mcp/toolResult.test.ts
index ed3a6bfa3a..6b44ea1ac2 100644
--- a/tests/boundary/mcp/toolResult.test.ts
+++ b/tests/boundary/mcp/toolResult.test.ts
@@ -14,6 +14,7 @@ import {
 import { toolContract } from "../../../src/contracts/toolContracts.js";
 import type { ToolContract } from "../../../src/contracts/toolContractTypes.js";
 import { err } from "../../../src/domain/result.js";
+import { EvidenceIntegrityError } from "../../../src/domain/evidenceErrors.js";
 import { HopperProcessError } from "../../../src/domain/hopperErrors.js";
 import { processScenarioSchema } from "../../../src/domain/process/processScenario.js";
 import { ToolResultDelivery } from "../../../src/server/toolResult.js";
@@ -482,30 +483,35 @@ describe("untrusted provenance on failed tool results", () => {
   });
 
   it("marks a recorded partial-observation error and its retention fallback", () => {
-    const recorded = delivery.toRecordedPartialErrorToolResult(
-      failure(),
-      "evidence-1",
-      { ok: true, value: "added" },
-      true,
+    const evidence = createEvidence(
+      undefined,
+      { id: "fixture", name: "Partial observation fixture", version: "1" },
+      { operation: "fixture", parameters: {}, result: { observed: true } },
     );
+    const original = failure().retainPartialObservation(evidence);
+    const recorded = delivery.toPartialErrorToolResult(original, true, () => ({
+      ok: true,
+      value: "added",
+    }));
     expect(recorded.structuredContent).toMatchObject({
       error: {
         details: {
           partial_observation: {
             kind: "retained-evidence",
-            evidence_id: "evidence-1",
+            evidence_id: evidence.evidence_id,
           },
         },
       },
     });
     expect(recorded._meta).toEqual(UNTRUSTED_TARGET_CONTENT);
-    const unrecorded = delivery.toRecordedPartialErrorToolResult(
-      failure(),
-      "evidence-1",
-      err(failure()),
-      true,
+    const unrecorded = delivery.toPartialErrorToolResult(original, true, () =>
+      err(new EvidenceIntegrityError("fixture rejects partial")),
     );
+    expect(unrecorded.structuredContent).toMatchObject({
+      error: { details: { partial_observation: evidence } },
+    });
     expect(unrecorded._meta).toEqual(UNTRUSTED_TARGET_CONTENT);
+    expect(original.partialObservation).toBe(evidence);
   });
 
   it("marks the response-budget error that replaces an oversized target-content result", () => {