diff --git a/tests/acceptance/applications/sourceMapPrefixCli.test.ts b/tests/acceptance/applications/sourceMapPrefixCli.test.ts
index 838e469249..af5f8eaec3 100644
--- a/tests/acceptance/applications/sourceMapPrefixCli.test.ts
+++ b/tests/acceptance/applications/sourceMapPrefixCli.test.ts
@@ -2,6 +2,7 @@ import { createHash } from "node:crypto";
 import { readFile, writeFile } from "node:fs/promises";
 import { join } from "node:path";
 
+import { TraceMap, originalPositionFor } from "@jridgewell/trace-mapping";
 import { expect } from "vitest";
 import { createTestTempDirectory } from "../../fixtures/temporaryDirectory.js";
 import { cliTest } from "../../support/cli/cliFixture.js";
@@ -85,6 +86,13 @@ cliTest.for(["CLI", "stdio MCP"] as const)(
         names: [],
         mappings: "ACAA",
       }),
+      "unnamed-empty.js.map": JSON.stringify({
+        version: 3,
+        sources: [null, "original.ts"],
+        sourcesContent: [null, original],
+        names: [],
+        mappings: "ACAA",
+      }),
     };
     await writeFixtureFiles(root, {
       ...maps,
@@ -92,13 +100,32 @@ cliTest.for(["CLI", "stdio MCP"] as const)(
         "export const absent = 1;\n//# sourceMappingURL=absent.js.map\n",
       "mixed.js":
         "export const answer = 42;\n//# sourceMappingURL=mixed.js.map\n",
+      "unnamed-empty.js":
+        "export const answer = 42;\n//# sourceMappingURL=unnamed-empty.js.map\n",
     });
+    for (const [mapPath, expectedSource] of [
+      ["absent.js.map", "unembedded.ts"],
+      ["mixed.js.map", "original.ts"],
+      ["unnamed-empty.js.map", "original.ts"],
+    ] as const)
+      expect(
+        originalPositionFor(new TraceMap(maps[mapPath], `file:///${mapPath}`), {
+          line: 1,
+          column: 0,
+        }).source,
+      ).toBe(`file:///${expectedSource}`);
     const { graph } = await analyzeJavaScriptDirectory(surface, cli, root);
     const digest = (text: string) =>
       createHash("sha256").update(text).digest("hex");
-    for (const [name, mapPath, content] of [
-      ["unembedded.ts", "absent.js.map", null],
-      ["original.ts", "mixed.js.map", original],
+    expect(
+      graph.nodes.filter(
+        (node) => node.identity.strategy === "source-map-original",
+      ),
+    ).toHaveLength(3);
+    for (const [name, mapPath, content, sourceIndex] of [
+      ["unembedded.ts", "absent.js.map", null, 0],
+      ["original.ts", "mixed.js.map", original, 1],
+      ["original.ts", "unnamed-empty.js.map", original, 1],
     ] as const) {
       const mapDigest = digest(maps[mapPath]);
       expect(graph.nodes).toContainEqual(
@@ -117,6 +144,9 @@ cliTest.for(["CLI", "stdio MCP"] as const)(
                 map_path: mapPath,
               }),
               properties: expect.objectContaining({
+                source_index: sourceIndex,
+                declaration_index: sourceIndex,
+                source_name_available: true,
                 content_available: content !== null,
               }),
               evidence: expect.objectContaining({
@@ -127,27 +157,77 @@ cliTest.for(["CLI", "stdio MCP"] as const)(
         }),
       );
     }
+    for (const [mapPath, content] of [
+      ["mixed.js.map", unnamed],
+      ["unnamed-empty.js.map", null],
+    ] as const)
+      expect(graph.nodes).toContainEqual(
+        expect.objectContaining({
+          kind: "unknown",
+          observations: expect.arrayContaining([
+            expect.objectContaining({
+              source_map_reference: null,
+              properties: expect.objectContaining({
+                source_index: 0,
+                declaration_index: 0,
+                source_name_available: false,
+                content_available: content !== null,
+                content_sha256: content === null ? null : digest(content),
+              }),
+              evidence: expect.objectContaining({
+                artifact: expect.objectContaining({
+                  sha256: digest(maps[mapPath]),
+                }),
+              }),
+            }),
+          ]),
+        }),
+      );
+    expect(graph.coverage.status).toBe("complete");
+    for (const [path, text] of Object.entries(maps))
+      expect(await readFile(join(root, path), "utf8")).toBe(text);
+  },
+);
+
+cliTest.for(["CLI", "stdio MCP"] as const)(
+  "rejects non-string source-map names without inventing originals through %s",
+  async (surface, { cli }) => {
+    const root = await createTestTempDirectory("rea-invalid-map-source-");
+    const mapText = JSON.stringify({
+      version: 3,
+      sources: [42, "discarded.ts"],
+      sourcesContent: [null, "export const answer: number = 42;"],
+      names: [],
+      mappings: "ACAA",
+    });
+    await writeFixtureFiles(root, { "invalid.js.map": mapText });
+    const { graph } = await analyzeJavaScriptDirectory(surface, cli, root);
+    expect(graph.coverage.status).toBe("partial");
+    expect(
+      graph.nodes.some(
+        (node) => node.identity.strategy === "source-map-original",
+      ),
+    ).toBe(false);
     expect(graph.nodes).toContainEqual(
       expect.objectContaining({
         kind: "unknown",
         observations: expect.arrayContaining([
           expect.objectContaining({
             properties: expect.objectContaining({
-              source_name_available: false,
-              content_available: true,
-              content_sha256: digest(unnamed),
+              operation: "parse-local-source-map",
             }),
             evidence: expect.objectContaining({
               artifact: expect.objectContaining({
-                sha256: digest(maps["mixed.js.map"]),
+                sha256: createHash("sha256").update(mapText).digest("hex"),
               }),
+              limitations: expect.arrayContaining([
+                "Source map contains a non-string source name.",
+              ]),
             }),
           }),
         ]),
       }),
     );
-    expect(graph.coverage.status).toBe("complete");
-    for (const [path, text] of Object.entries(maps))
-      expect(await readFile(join(root, path), "utf8")).toBe(text);
+    expect(await readFile(join(root, "invalid.js.map"), "utf8")).toBe(mapText);
   },
 );
diff --git a/tests/boundary/filesystem/javascriptArtifactReconstruction.test.ts b/tests/boundary/filesystem/javascriptArtifactReconstruction.test.ts
index 7f0a44c1de..aabfdd19b8 100644
--- a/tests/boundary/filesystem/javascriptArtifactReconstruction.test.ts
+++ b/tests/boundary/filesystem/javascriptArtifactReconstruction.test.ts
@@ -136,7 +136,6 @@ it.each([
   ["a non-array sourcesContent value", { sourcesContent: "source" }],
   ["a non-string, non-null source entry", { sourcesContent: [42] }],
   ["a source-content array with the wrong length", { sourcesContent: [] }],
-  ["a non-string source name", { sources: [42] }],
 ])(
   "reports %s as an invalid local source map",
   async (_description, content) => {