diff --git a/src/javascript/sourceMaps/SourceMapCommand.ts b/src/javascript/sourceMaps/SourceMapCommand.ts
index 4b24e8ed9a..0b7e17dd6f 100644
--- a/src/javascript/sourceMaps/SourceMapCommand.ts
+++ b/src/javascript/sourceMaps/SourceMapCommand.ts
@@ -106,14 +106,16 @@ export const runSourceMapCommand = async (
         ? new AnalysisCancelledError(OPERATION, {
             cause: options.signal.reason,
           })
-        : new ProviderAdapterError(PROVIDER, OPERATION, {
-            cause,
-            diagnostics: {
-              map_path: path,
-              error_message: message(cause),
-              phase: "process_ownership_preparation",
-            },
-          }),
+        : cause instanceof AnalysisError
+          ? cause
+          : new ProviderAdapterError(PROVIDER, OPERATION, {
+              cause,
+              diagnostics: {
+                map_path: path,
+                error_message: message(cause),
+                phase: "process_ownership_preparation",
+              },
+            }),
     );
   }
   const deadline = new ProviderStartupDeadline(
diff --git a/tests/boundary/javascript/sourceMapPreparation.test.ts b/tests/boundary/javascript/sourceMapPreparation.test.ts
new file mode 100644
index 0000000000..5d9b01ff05
--- /dev/null
+++ b/tests/boundary/javascript/sourceMapPreparation.test.ts
@@ -0,0 +1,74 @@
+import { expect, it, vi } from "vitest";
+import { AnalysisCancelledError } from "../../../src/domain/analysisErrorCore.js";
+import { ProviderAdapterError } from "../../../src/domain/providerAdapterError.js";
+import { ProviderCleanupError } from "../../../src/domain/providerCleanupError.js";
+import { runSourceMapCommand } from "../../../src/javascript/sourceMaps/SourceMapCommand.js";
+
+it.each([
+  null,
+  new ProviderCleanupError("caller", ["caller-owned-resource"], {}),
+])(
+  "preserves opaque cancellation during ownership preparation: %s",
+  async (reason) => {
+    const controller = new AbortController();
+    const createRuntime = vi.fn(async () => {
+      throw new Error("Cancelled preparation must not acquire a runtime");
+    });
+    const launcher = vi.fn(async () => {
+      throw new Error("Cancelled preparation must not launch a codec");
+    });
+    const result = await runSourceMapCommand(
+      "{}",
+      "/selected.map",
+      { signal: controller.signal },
+      {
+        prepareOwnership: async (signal) => {
+          controller.abort(reason);
+          signal?.throwIfAborted();
+        },
+        createRuntime,
+        launcher,
+      },
+    );
+    if (result.ok) throw new Error("Preparation must return cancellation");
+    expect(result.error).toBeInstanceOf(AnalysisCancelledError);
+    expect(result.error.cause).toBe(reason);
+    expect(result.error.cleanupIncomplete).toBe(false);
+    expect(result.error.cleanupResources).toEqual([]);
+    if (reason instanceof ProviderCleanupError) {
+      expect(reason.cleanupIncomplete).toBe(true);
+      expect(reason.cleanupResources).toEqual(["caller-owned-resource"]);
+    }
+    expect(createRuntime).not.toHaveBeenCalled();
+    expect(launcher).not.toHaveBeenCalled();
+  },
+);
+
+it("retains diagnostics for an unknown ownership preparation failure", async () => {
+  const cause = new Error("unexpected ownership failure");
+  const createRuntime = vi.fn(async () => {
+    throw new Error("Failed preparation must not acquire a runtime");
+  });
+  const launcher = vi.fn(async () => {
+    throw new Error("Failed preparation must not launch a codec");
+  });
+  const result = await runSourceMapCommand("{}", "/selected.map", undefined, {
+    prepareOwnership: async () => {
+      throw cause;
+    },
+    createRuntime,
+    launcher,
+  });
+  if (result.ok) throw new Error("Preparation must return its failure");
+  expect(result.error).toBeInstanceOf(ProviderAdapterError);
+  expect(result.error.cause).toBe(cause);
+  expect(result.error).toMatchObject({
+    diagnostics: {
+      map_path: "/selected.map",
+      error_message: cause.message,
+      phase: "process_ownership_preparation",
+    },
+  });
+  expect(createRuntime).not.toHaveBeenCalled();
+  expect(launcher).not.toHaveBeenCalled();
+});
diff --git a/tests/boundary/mcp/webSourceLocationMcp.test.ts b/tests/boundary/mcp/webSourceLocationMcp.test.ts
index df40a0aecb..0afa5d0cbe 100644
--- a/tests/boundary/mcp/webSourceLocationMcp.test.ts
+++ b/tests/boundary/mcp/webSourceLocationMcp.test.ts
@@ -2,7 +2,8 @@ import { traceSourceMap } from "../../../src/javascript/sourceMaps/TraceSourceMa
 import { webSourceLocationArgs as args } from "../../fixtures/webSourceLocation.js";
 import { Client, InMemoryTransport } from "@modelcontextprotocol/client";
 import { Ajv2020 } from "ajv/dist/2020.js";
-import { expect, it, onTestFinished } from "vitest";
+import { createTestTempDirectory } from "../../fixtures/temporaryDirectory.js";
+import { expect, it, onTestFinished, vi } from "vitest";
 import { WebSourceLocationService } from "../../../src/application/WebSourceLocationService.js";
 import { toolContract } from "../../../src/contracts/toolContracts.js";
 import { parseEvidence } from "../../../src/domain/evidence.js";
@@ -10,6 +11,10 @@ import { ok } from "../../../src/domain/result.js";
 import { createServer } from "../../../src/server/createServer.js";
 import { createTestBinarySession } from "../../fixtures/binarySession.js";
 import { webSourceLocationFixture } from "../../fixtures/webSourceLocation.js";
+import { SourceMapDecoder } from "../../../src/javascript/sourceMaps/SourceMapDecoder.js";
+import { createSystemProcessOwnershipHost } from "../../../src/process/ProcessOwnershipObservation.js";
+import { createApplicationMcpHarness } from "../../fixtures/applicationMcpHarness.js";
+import { parseMcpToolError } from "../../fixtures/mcpToolError.js";
 
 it("publishes valid SDK schemas and records the named module trace without a binary target", async () => {
   const service = new WebSourceLocationService(
@@ -83,3 +88,54 @@ it("publishes valid SDK schemas and records the named module trace without a bin
   });
   expect(invalid.isError).toBe(true);
 });
+
+it("preserves missing Linux ps capability and recovery through source-map tracing", async () => {
+  const directory = await createTestTempDirectory("source-map-missing-ps-");
+  const prepare = createSystemProcessOwnershipHost("linux", {
+    PATH: directory,
+  }).prepare;
+  if (prepare === undefined)
+    throw new Error("Ownership preparation is required");
+  const createRuntime = vi.fn(async () => {
+    throw new Error("Missing prerequisite must not acquire a runtime");
+  });
+  const launcher = vi.fn(async () => {
+    throw new Error("Missing prerequisite must not launch a codec");
+  });
+  const decoder = new SourceMapDecoder({
+    prepareOwnership: prepare,
+    createRuntime,
+    launcher,
+  });
+  const harness = await createApplicationMcpHarness({
+    serverOptions: {
+      webSourceLocation: new WebSourceLocationService(
+        { load: async () => ok(webSourceLocationFixture()) },
+        decoder,
+      ),
+    },
+  });
+  onTestFinished(() => harness.close());
+  for (let attempt = 0; attempt < 2; attempt += 1) {
+    const response = await harness.client.callTool({
+      name: "trace_web_source_location",
+      arguments: args,
+    });
+    const { error } = parseMcpToolError(response);
+    expect(error).toMatchObject({
+      code: "capability_unavailable",
+      category: "unsupported_provider",
+      retryable: false,
+      message: expect.stringContaining("procps-compatible ps"),
+      remediation: { action: expect.stringContaining("procps-compatible ps") },
+      details: {
+        provider_id: "process-ownership",
+        operation: "prepare_owned_process",
+        reason: expect.stringContaining("ENOENT"),
+      },
+    });
+  }
+  await harness.client.ping();
+  expect(createRuntime).not.toHaveBeenCalled();
+  expect(launcher).not.toHaveBeenCalled();
+});