diff --git a/src/application/BrowserObservationService.test.ts b/src/application/BrowserObservationService.test.ts
index 61f23afdb4..1181394140 100644
--- a/src/application/BrowserObservationService.test.ts
+++ b/src/application/BrowserObservationService.test.ts
@@ -8,6 +8,11 @@ import {
   AnalysisOutputError,
 } from "../domain/analysisErrorCore.js";
 import { projectAnalysisError } from "../domain/analysisErrorProjection.js";
+import {
+  expectDroppedPartial,
+  expectKeptPartial,
+  expectOwnerError,
+} from "./ownerObservationExpectation.js";
 import { BrowserObservationError } from "../domain/browserObservationError.js";
 import { err, ok } from "../domain/result.js";
 import { passiveNetworkCapture } from "../../tests/fixtures/passiveNetworkCapture.js";
@@ -243,16 +248,7 @@ it("keeps page cancellation when the retained inspection is incomplete", async (
     include_script_sources: false,
   });
   const result = await inspectWebPage(browser, pageInput);
-  expect(result.ok).toBe(false);
-  if (result.ok) throw new Error("Expected cancellation");
-  expect(result.error).toBe(failure);
-  expect(result.error.cause).toBe(reason);
-  expect(result.error.partialObservation).toBe(partial);
-  expect(result.error.secondaryFailures).toHaveLength(0);
-  expect(projectAnalysisError(result.error)).toMatchObject({
-    code: "cancelled",
-    details: { partial_observation: partial },
-  });
+  expectKeptPartial(expectOwnerError(result, failure, reason), partial);
 });
 
 it("keeps bundle cancellation and an earlier failure when retained facts are incomplete", async () => {
@@ -278,16 +274,13 @@ it("keeps bundle cancellation and an earlier failure when retained facts are inc
       analyzeBundle: async () => err(failure),
     } as unknown as BrowserObservationPort;
     const result = await analyzeWebBundle(browser, selected);
-    expect(result.ok).toBe(false);
-    if (result.ok) throw new Error("Expected the owner failure");
-    expect(result.error).toBe(failure);
-    expect(result.error.partialObservation).toBe(partial);
-    expect(result.error.secondaryFailures).toHaveLength(0);
+    expectKeptPartial(
+      expectOwnerError(result, failure, failure.cause),
+      partial,
+      failure === timedOut ? "provider_timeout" : "cancelled",
+    );
   }
-  expect(projectAnalysisError(cancelled)).toMatchObject({
-    code: "cancelled",
-    details: { partial_observation: partial },
-  });
+  expect(projectAnalysisError(cancelled).code).toBe("cancelled");
 });
 
 const pageInput = () =>
@@ -347,22 +340,12 @@ it.each([
       operation === "inspect_web_page"
         ? await inspectWebPage(browserReturning(failure), pageInput())
         : await analyzeWebBundle(browserReturning(failure), bundleInput());
-    expect(result.ok).toBe(false);
-    if (result.ok) throw new Error("Expected cancellation");
-    expect(result.error).toBe(failure);
-    expect(result.error.cause).toBe(reason);
-    expect(result.error.partialObservation).toBeUndefined();
-    expect(result.error.secondaryFailures).toMatchObject([
-      {
-        _tag: "AnalysisOutputError",
-        operation,
-        reason: "Browser provider retained a non-JSON incomplete observation.",
-      },
-    ]);
-    expect(projectAnalysisError(result.error)).toMatchObject({
-      code: "cancelled",
-    });
-    expect(projectAnalysisError(result.error).details).not.toHaveProperty(
+    const error = expectOwnerError(result, failure, reason);
+    expectDroppedPartial(
+      error,
+      "Browser provider retained a non-JSON incomplete observation.",
+    );
+    expect(projectAnalysisError(error).details).not.toHaveProperty(
       "partial_observation",
     );
   },
@@ -387,17 +370,16 @@ it.each([
     const failure = new BrowserObservationError("inspect_web_page", "timeout", {
       partialObservation: partial as never,
     });
-    const result = await inspectWebPage(browserReturning(failure), pageInput());
-    expect(result.ok).toBe(false);
-    if (result.ok) throw new Error("Expected timeout");
-    expect(result.error).toBe(failure);
-    expect(result.error.partialObservation).toBeUndefined();
-    expect(result.error.secondaryFailures[0]).toBeInstanceOf(
-      AnalysisOutputError,
+    const error = expectOwnerError(
+      await inspectWebPage(browserReturning(failure), pageInput()),
+      failure,
+      undefined,
     );
-    expect(projectAnalysisError(result.error)).toMatchObject({
-      code: "provider_timeout",
-      category: "timeout",
-    });
+    expectDroppedPartial(
+      error,
+      "Browser provider retained a non-JSON incomplete observation.",
+      "provider_timeout",
+    );
+    expect(projectAnalysisError(error).category).toBe("timeout");
   },
 );
diff --git a/src/application/BrowserScenarioCaptureService.test.ts b/src/application/BrowserScenarioCaptureService.test.ts
index 77ab83e390..fb4342e3f9 100644
--- a/src/application/BrowserScenarioCaptureService.test.ts
+++ b/src/application/BrowserScenarioCaptureService.test.ts
@@ -4,7 +4,6 @@ import {
   AnalysisCancelledError,
   AnalysisOutputError,
 } from "../domain/analysisErrorCore.js";
-import { projectAnalysisError } from "../domain/analysisErrorProjection.js";
 import { BrowserObservationError } from "../domain/browserObservationError.js";
 import { parseEvidence } from "../domain/evidence.js";
 import { browserScenarioInputSchema } from "../domain/browserScenario.js";
@@ -16,6 +15,11 @@ import { err, ok } from "../domain/result.js";
 import { scriptScenarioFixture } from "../../tests/fixtures/webScriptCapture.js";
 import type { BrowserScenarioCapturePort } from "./BrowserScenarioCapturePort.js";
 import { captureBrowserScenario } from "./BrowserScenarioCaptureService.js";
+import {
+  expectDroppedPartial,
+  expectKeptPartial,
+  expectOwnerError,
+} from "./ownerObservationExpectation.js";
 
 const scenario = browserScenarioInputSchema.parse({
   browser: { mode: "launch", executable_path: "/fixture/chrome" },
@@ -138,16 +142,7 @@ it("keeps startup cancellation and its incomplete capture", async () => {
     captureScenario: async () => err(failure),
   };
   const result = await captureBrowserScenario(provider, scenario);
-  expect(result.ok).toBe(false);
-  if (result.ok) throw new Error("Expected cancellation");
-  expect(result.error).toBe(failure);
-  expect(result.error.cause).toBe(reason);
-  expect(result.error.partialObservation).toBe(partial);
-  expect(result.error.secondaryFailures).toHaveLength(0);
-  expect(projectAnalysisError(result.error)).toMatchObject({
-    code: "cancelled",
-    details: { partial_observation: partial },
-  });
+  expectKeptPartial(expectOwnerError(result, failure, reason), partial);
 });
 
 it.each([{ steps: [undefined] }, { started_at: Number.NaN }])(
@@ -167,22 +162,10 @@ it.each([{ steps: [undefined] }, { started_at: Number.NaN }])(
       captureScenario: async () => err(failure),
     };
     const result = await captureBrowserScenario(provider, scenario);
-    expect(result.ok).toBe(false);
-    if (result.ok) throw new Error("Expected cancellation");
-    expect(result.error).toBe(failure);
-    expect(result.error.cause).toBe(reason);
-    expect(result.error.partialObservation).toBeUndefined();
-    expect(result.error.secondaryFailures).toMatchObject([
-      {
-        _tag: "AnalysisOutputError",
-        operation: "capture_browser_scenario",
-        reason:
-          "Browser scenario provider retained a non-JSON incomplete observation.",
-      },
-    ]);
-    expect(projectAnalysisError(result.error)).toMatchObject({
-      code: "cancelled",
-    });
+    expectDroppedPartial(
+      expectOwnerError(result, failure, reason),
+      "Browser scenario provider retained a non-JSON incomplete observation.",
+    );
   },
 );
 
diff --git a/src/application/WebRuntimeService.test.ts b/src/application/WebRuntimeService.test.ts
index c26b870581..82271332c5 100644
--- a/src/application/WebRuntimeService.test.ts
+++ b/src/application/WebRuntimeService.test.ts
@@ -13,6 +13,12 @@ import {
 } from "../domain/analysisErrorCore.js";
 import { projectAnalysisError } from "../domain/analysisErrorProjection.js";
 import { ProviderCleanupError } from "../domain/providerCleanupError.js";
+import {
+  expectDroppedPartial,
+  expectKeptPartial,
+  expectOwnerError,
+} from "./ownerObservationExpectation.js";
+import type { AnalysisError } from "../domain/analysisErrorBase.js";
 import { parseEvidence } from "../domain/evidence.js";
 
 it("rejects malformed input and prior cancellation without calling a provider", async () => {
@@ -166,6 +172,32 @@ it("retains completed execution Evidence on late abort and keeps invalid output
   if (!invalid.ok) expect(invalid.error).toBeInstanceOf(AnalysisOutputError);
 });
 
+const callRuntime = (
+  operation: "observe" | "inspect",
+  failure: AnalysisError,
+) => {
+  const service = new WebRuntimeService({
+    identity: () => ({
+      id: "web-runtime",
+      name: "Runtime fixture",
+      version: "1",
+    }),
+    observeExecution: async () => err(failure),
+    inspectEventListeners: async () => err(failure),
+  });
+  return operation === "observe"
+    ? service.observe({
+        cdp_endpoint: "http://127.0.0.1:9222",
+        target_id: "selected-page",
+        observation_ms: 5,
+      })
+    : service.inspect({
+        cdp_endpoint: "http://127.0.0.1:9222",
+        target_id: "selected-page",
+        selector: "#selected",
+      });
+};
+
 it.each([
   {
     operation: "observe" as const,
@@ -191,37 +223,10 @@ it.each([
         : "inspect_web_event_listeners",
       { cause: reason, partialObservation: partial as never },
     );
-    const service = new WebRuntimeService({
-      identity: () => ({
-        id: "web-runtime",
-        name: "Runtime fixture",
-        version: "1",
-      }),
-      observeExecution: async () => err(failure),
-      inspectEventListeners: async () => err(failure),
-    });
-    const result =
-      operation === "observe"
-        ? await service.observe({
-            cdp_endpoint: "http://127.0.0.1:9222",
-            target_id: "selected-page",
-            observation_ms: 5,
-          })
-        : await service.inspect({
-            cdp_endpoint: "http://127.0.0.1:9222",
-            target_id: "selected-page",
-            selector: "#selected",
-          });
-    expect(result.ok).toBe(false);
-    if (result.ok) throw new Error("Expected cancellation");
-    expect(result.error).toBe(failure);
-    expect(result.error.cause).toBe(reason);
-    expect(result.error.partialObservation).toBe(partial);
-    expect(result.error.secondaryFailures).toHaveLength(0);
-    expect(projectAnalysisError(result.error)).toMatchObject({
-      code: "cancelled",
-      details: { partial_observation: partial },
-    });
+    expectKeptPartial(
+      expectOwnerError(await callRuntime(operation, failure), failure, reason),
+      partial,
+    );
   },
 );
 
@@ -253,38 +258,10 @@ it.each([
         : "inspect_web_event_listeners",
       { cause: reason, partialObservation: partial as never },
     );
-    const service = new WebRuntimeService({
-      identity: () => ({
-        id: "web-runtime",
-        name: "Runtime fixture",
-        version: "1",
-      }),
-      observeExecution: async () => err(failure),
-      inspectEventListeners: async () => err(failure),
-    });
-    const result =
-      operation === "observe"
-        ? await service.observe({
-            cdp_endpoint: "http://127.0.0.1:9222",
-            target_id: "selected-page",
-            observation_ms: 5,
-          })
-        : await service.inspect({
-            cdp_endpoint: "http://127.0.0.1:9222",
-            target_id: "selected-page",
-            selector: "#selected",
-          });
-    expect(result.ok).toBe(false);
-    if (result.ok) throw new Error("Expected cancellation");
-    expect(result.error).toBe(failure);
-    expect(result.error.cause).toBe(reason);
-    expect(result.error.partialObservation).toBeUndefined();
-    expect(result.error.secondaryFailures).toMatchObject([
-      { _tag: "AnalysisOutputError", reason: outputReason },
-    ]);
-    expect(projectAnalysisError(result.error)).toMatchObject({
-      code: "cancelled",
-    });
+    expectDroppedPartial(
+      expectOwnerError(await callRuntime(operation, failure), failure, reason),
+      outputReason,
+    );
   },
 );
 
@@ -295,27 +272,15 @@ it("drops a non-JSON execution partial and keeps timeout primary", async () => {
       window: { requested_ms: 5 },
     } as never,
   });
-  const service = new WebRuntimeService({
-    identity: () => ({
-      id: "web-runtime",
-      name: "Runtime fixture",
-      version: "1",
-    }),
-    observeExecution: async () => err(failure),
-    inspectEventListeners: async () => err(failure),
-  });
-  const result = await service.observe({
-    cdp_endpoint: "http://127.0.0.1:9222",
-    target_id: "selected-page",
-    observation_ms: 5,
-  });
-  expect(result.ok).toBe(false);
-  if (result.ok) throw new Error("Expected timeout");
-  expect(result.error).toBe(failure);
-  expect(result.error.partialObservation).toBeUndefined();
-  expect(result.error.secondaryFailures[0]).toBeInstanceOf(AnalysisOutputError);
-  expect(projectAnalysisError(result.error)).toMatchObject({
-    code: "provider_timeout",
-    category: "timeout",
-  });
+  const error = expectOwnerError(
+    await callRuntime("observe", failure),
+    failure,
+    undefined,
+  );
+  expectDroppedPartial(
+    error,
+    "Provider retained a non-JSON incomplete execution observation.",
+    "provider_timeout",
+  );
+  expect(projectAnalysisError(error).category).toBe("timeout");
 });
diff --git a/src/application/javascript/ElectronObservationService.test.ts b/src/application/javascript/ElectronObservationService.test.ts
index 8a73812df3..3f1296e62c 100644
--- a/src/application/javascript/ElectronObservationService.test.ts
+++ b/src/application/javascript/ElectronObservationService.test.ts
@@ -5,7 +5,6 @@ import {
   AnalysisCancelledError,
   AnalysisOutputError,
 } from "../../domain/analysisErrorCore.js";
-import { projectAnalysisError } from "../../domain/analysisErrorProjection.js";
 import { ProviderCleanupError } from "../../domain/providerCleanupError.js";
 import { parseEvidence } from "../../domain/evidence.js";
 import {
@@ -19,6 +18,11 @@ import {
   inspectElectronPage,
   listElectronTargets,
 } from "./ElectronObservationService.js";
+import {
+  expectDroppedPartial,
+  expectKeptPartial,
+  expectOwnerError,
+} from "../ownerObservationExpectation.js";
 
 const identity = { id: "electron-fixture", name: "Fixture", version: "1" };
 const input = inspectElectronPageInputSchema.parse({
@@ -264,16 +268,7 @@ it("keeps cancellation when the retained Electron inspection is incomplete", asy
     inspectPage: async () => err(failure),
   };
   const result = await inspectElectronPage(provider, input);
-  expect(result.ok).toBe(false);
-  if (result.ok) throw new Error("Expected cancellation");
-  expect(result.error).toBe(failure);
-  expect(result.error.cause).toBe(reason);
-  expect(result.error.partialObservation).toBe(partial);
-  expect(result.error.secondaryFailures).toHaveLength(0);
-  expect(projectAnalysisError(result.error)).toMatchObject({
-    code: "cancelled",
-    details: { partial_observation: partial },
-  });
+  expectKeptPartial(expectOwnerError(result, failure, reason), partial);
 });
 
 it.each([
@@ -300,20 +295,9 @@ it.each([
       inspectPage: async () => err(failure),
     };
     const result = await inspectElectronPage(provider, input);
-    expect(result.ok).toBe(false);
-    if (result.ok) throw new Error("Expected cancellation");
-    expect(result.error).toBe(failure);
-    expect(result.error.cause).toBe(reason);
-    expect(result.error.partialObservation).toBeUndefined();
-    expect(result.error.secondaryFailures).toMatchObject([
-      {
-        _tag: "AnalysisOutputError",
-        operation: "inspect_electron_page",
-        reason: "Electron provider retained a non-JSON incomplete observation.",
-      },
-    ]);
-    expect(projectAnalysisError(result.error)).toMatchObject({
-      code: "cancelled",
-    });
+    expectDroppedPartial(
+      expectOwnerError(result, failure, reason),
+      "Electron provider retained a non-JSON incomplete observation.",
+    );
   },
 );
diff --git a/src/application/javascript/JavaScriptRuntimeObservationService.test.ts b/src/application/javascript/JavaScriptRuntimeObservationService.test.ts
index b04da81ae5..0e1776e31c 100644
--- a/src/application/javascript/JavaScriptRuntimeObservationService.test.ts
+++ b/src/application/javascript/JavaScriptRuntimeObservationService.test.ts
@@ -5,7 +5,6 @@ import {
   AnalysisCancelledError,
   AnalysisOutputError,
 } from "../../domain/analysisErrorCore.js";
-import { projectAnalysisError } from "../../domain/analysisErrorProjection.js";
 import { err, ok } from "../../domain/result.js";
 import { parseEvidence } from "../../domain/evidence.js";
 import type { JavaScriptRuntimeTargetList } from "../../domain/javascript/javascriptRuntimeObservation.js";
@@ -15,6 +14,11 @@ import {
   listJavaScriptRuntimeTargets,
   observeJavaScriptRuntime,
 } from "./JavaScriptRuntimeObservationService.js";
+import {
+  expectDroppedPartial,
+  expectKeptPartial,
+  expectOwnerError,
+} from "../ownerObservationExpectation.js";
 
 it("preserves failed Inspector cleanup when cancellation occurs during observation", async () => {
   const controller = new AbortController();
@@ -337,16 +341,7 @@ it("keeps cancellation when the retained runtime observation is incomplete", asy
     target_id: "target",
     observation_ms: 0,
   });
-  expect(result.ok).toBe(false);
-  if (result.ok) throw new Error("Expected cancellation");
-  expect(result.error).toBe(failure);
-  expect(result.error.cause).toBe(reason);
-  expect(result.error.partialObservation).toBe(partial);
-  expect(result.error.secondaryFailures).toHaveLength(0);
-  expect(projectAnalysisError(result.error)).toMatchObject({
-    code: "cancelled",
-    details: { partial_observation: partial },
-  });
+  expectKeptPartial(expectOwnerError(result, failure, reason), partial);
 });
 
 it.each([{ scripts: [undefined] }, { elapsed_ms: Number.NaN }])(
@@ -368,20 +363,9 @@ it.each([{ scripts: [undefined] }, { elapsed_ms: Number.NaN }])(
       target_id: "target",
       observation_ms: 0,
     });
-    expect(result.ok).toBe(false);
-    if (result.ok) throw new Error("Expected cancellation");
-    expect(result.error).toBe(failure);
-    expect(result.error.cause).toBe(reason);
-    expect(result.error.partialObservation).toBeUndefined();
-    expect(result.error.secondaryFailures).toMatchObject([
-      {
-        _tag: "AnalysisOutputError",
-        operation: "observe_javascript_runtime",
-        reason: "Inspector retained a non-JSON incomplete observation.",
-      },
-    ]);
-    expect(projectAnalysisError(result.error)).toMatchObject({
-      code: "cancelled",
-    });
+    expectDroppedPartial(
+      expectOwnerError(result, failure, reason),
+      "Inspector retained a non-JSON incomplete observation.",
+    );
   },
 );
diff --git a/src/application/ownerObservationExpectation.ts b/src/application/ownerObservationExpectation.ts
new file mode 100644
index 0000000000..d466c57812
--- /dev/null
+++ b/src/application/ownerObservationExpectation.ts
@@ -0,0 +1,44 @@
+import { expect } from "vitest";
+import type { AnalysisError } from "../domain/analysisErrorBase.js";
+import { projectAnalysisError } from "../domain/analysisErrorProjection.js";
+import type { Result } from "../domain/result.js";
+
+/** Assert the service returned the same owner error and its cause. */
+export const expectOwnerError = <T>(
+  result: Result<T, AnalysisError>,
+  failure: AnalysisError,
+  cause: unknown,
+): AnalysisError => {
+  expect(result.ok).toBe(false);
+  if (result.ok) throw new Error("Expected the owner failure");
+  expect(result.error).toBe(failure);
+  expect(result.error.cause).toBe(cause);
+  return result.error;
+};
+
+/** A JSON-safe incomplete observation stays on the owner error. */
+export const expectKeptPartial = (
+  error: AnalysisError,
+  partial: unknown,
+  code: "cancelled" | "provider_timeout" = "cancelled",
+): void => {
+  expect(error.partialObservation).toBe(partial);
+  expect(error.secondaryFailures).toHaveLength(0);
+  expect(projectAnalysisError(error)).toMatchObject({
+    code,
+    details: { partial_observation: partial },
+  });
+};
+
+/** A non-JSON partial is cleared and recorded as a secondary output failure. */
+export const expectDroppedPartial = (
+  error: AnalysisError,
+  reason: string,
+  code: "cancelled" | "provider_timeout" = "cancelled",
+): void => {
+  expect(error.partialObservation).toBeUndefined();
+  expect(error.secondaryFailures).toMatchObject([
+    { _tag: "AnalysisOutputError", reason },
+  ]);
+  expect(projectAnalysisError(error).code).toBe(code);
+};