diff --git a/docs/mcp-contracts.md b/docs/mcp-contracts.md
index c85f790e8c..e11910c896 100644
--- a/docs/mcp-contracts.md
+++ b/docs/mcp-contracts.md
@@ -47,6 +47,11 @@ derived metadata keep their upstream representation. Read function results from
 `normalized_result`; older retained Evidence keeps its original representation
 and identity.
 
+Artifact source-map filename relationships require a unique, identified regular
+file at the sibling path. A known directory cannot be the mapped file; the map
+retains its actual container relation. This admission does not establish source
+byte correspondence or decode the map's original source paths.
+
 Artifact inventories declare `coverage.scope` (`root` or `container-entries`)
 and `coverage.status` (`complete` or `unknown`) independently of diagnostic
 wording. Comparison requires matching scopes, complete graph members and complete
diff --git a/src/artifacts/inventory/ArtifactGraphConstruction.ts b/src/artifacts/inventory/ArtifactGraphConstruction.ts
index 354299b502..c74368b13f 100644
--- a/src/artifacts/inventory/ArtifactGraphConstruction.ts
+++ b/src/artifacts/inventory/ArtifactGraphConstruction.ts
@@ -332,7 +332,9 @@ export const createArtifactEdges = (
     const sourceCandidates =
       sourcePath === undefined ? [] : (byPath.get(sourcePath) ?? []);
     const mappedSource =
-      sourceCandidates.length === 1 && sourceCandidates[0]?.artifact_id !== null
+      sourceCandidates.length === 1 &&
+      sourceCandidates[0]?.entry_kind === "file" &&
+      sourceCandidates[0].artifact_id !== null
         ? sourceCandidates[0]
         : undefined;
     if (sourcePath !== undefined) {
@@ -342,7 +344,9 @@ export const createArtifactEdges = (
               occurrence: `Source-map target is unknown because multiple occurrences share ${JSON.stringify(sourcePath)}.`,
               coverage: `Source-map relationships are unknown because multiple occurrences share ${JSON.stringify(sourcePath)}.`,
             }
-          : sourceCandidates.length === 1 && mappedSource === undefined
+          : sourceCandidates.length === 1 &&
+              sourceCandidates[0]?.entry_kind === "file" &&
+              mappedSource === undefined
             ? {
                 occurrence: `Source-map target identity is unknown because the matching occurrence at ${JSON.stringify(sourcePath)} has no content identity.`,
                 coverage: `Source-map relationships are unknown because the matching occurrence at ${JSON.stringify(sourcePath)} has no content identity.`,
diff --git a/tests/boundary/filesystem/artifactSourceMapTargets.test.ts b/tests/boundary/filesystem/artifactSourceMapTargets.test.ts
new file mode 100644
index 0000000000..6327ce9529
--- /dev/null
+++ b/tests/boundary/filesystem/artifactSourceMapTargets.test.ts
@@ -0,0 +1,96 @@
+import { writeFile } from "node:fs/promises";
+import { join } from "node:path";
+import { TextReader, Uint8ArrayWriter, ZipWriter } from "@zip.js/zip.js";
+import { expect, it } from "vitest";
+import { createTestTempDirectory } from "../../fixtures/temporaryDirectory.js";
+import { inventoryArtifact } from "../../fixtures/artifactInventory.js";
+
+it.each([
+  "directory",
+  "directory-with-child",
+  "file",
+  "directory-map",
+  "missing",
+])(
+  "admits only a regular mapped file while retaining ZIP containment (%s)",
+  async (target) => {
+    const root = await createTestTempDirectory("rea-map-target-kind-");
+    const path = join(root, "sample.zip");
+    const writer = new ZipWriter(new Uint8ArrayWriter());
+    if (target.startsWith("directory") && target !== "directory-map")
+      await writer.add("main.js/", undefined, { directory: true });
+    if (target === "directory-with-child")
+      await writer.add("main.js/child.txt", new TextReader("child"));
+    if (target === "file" || target === "directory-map")
+      await writer.add("main.js", new TextReader("export const answer = 42;"));
+    if (target === "directory-map")
+      await writer.add("main.js.map/", undefined, { directory: true });
+    else
+      await writer.add(
+        "main.js.map",
+        new TextReader(
+          JSON.stringify({
+            version: 3,
+            file: "main.js",
+            sources: ["input.ts"],
+            sourcesContent: ["export const answer = 42;"],
+            names: [],
+            mappings: "AAAA",
+          }),
+        ),
+      );
+    await writeFile(path, await writer.close());
+    const inventory = await inventoryArtifact(path);
+    const map = inventory.occurrences.find(
+      ({ logical_path }) => logical_path === "main.js.map",
+    );
+    const main = inventory.occurrences.find(
+      ({ logical_path }) => logical_path === "main.js",
+    );
+    const carrier = inventory.occurrences.find(
+      ({ logical_path }) => logical_path === ".",
+    );
+    if (map === undefined || carrier === undefined)
+      throw new Error("Expected map and carrier");
+    expect(inventory.coverage.status).toBe("complete");
+    expect(map.parent_occurrence_id).toBe(carrier.occurrence_id);
+    expect(
+      inventory.edges.find(
+        ({ occurrence_id }) => occurrence_id === map.occurrence_id,
+      ),
+    ).toMatchObject({
+      relation: target === "file" ? "maps-source" : "contains",
+      parent_artifact_id:
+        target === "file" ? main?.artifact_id : carrier.artifact_id,
+    });
+    expect(map.limitations).toEqual([]);
+    if (target.startsWith("directory") && target !== "directory-map") {
+      expect(main).toMatchObject({
+        entry_kind: "directory",
+        artifact_kind: "container",
+      });
+      expect(
+        inventory.edges.find(
+          ({ occurrence_id }) => occurrence_id === main?.occurrence_id,
+        ),
+      ).toMatchObject({
+        relation: "contains",
+        parent_artifact_id: carrier.artifact_id,
+      });
+    }
+    if (target === "directory-with-child") {
+      const child = inventory.occurrences.find(
+        ({ logical_path }) => logical_path === "main.js/child.txt",
+      );
+      expect(child?.parent_occurrence_id).toBe(main?.occurrence_id);
+      expect(
+        inventory.edges.find(
+          ({ occurrence_id }) => occurrence_id === child?.occurrence_id,
+        ),
+      ).toMatchObject({
+        relation: "contains",
+        parent_artifact_id: main?.artifact_id,
+      });
+    }
+  },
+);