diff --git a/lib/pipeline/sources.ts b/lib/pipeline/sources.ts
index 090284e..4dbe1df 100644
--- a/lib/pipeline/sources.ts
+++ b/lib/pipeline/sources.ts
@@ -446,9 +446,8 @@ export async function approveCandidate(
     };
   }
 
-  // Write to {product_dir}/source/{stable_filename}
   const filename = stableFilenameFor(cand.doc_type);
-  const sourceDir = path.join(ctx.product_dir, "source");
+  const sourceDir = sourceDirForScope(ctx, cand.scope);
   fs.mkdirSync(sourceDir, { recursive: true });
   const targetAbs = path.join(sourceDir, filename);
   const tmp = `${targetAbs}.tmp-${process.pid}-${Date.now()}`;
@@ -579,7 +578,18 @@ function sourcesYamlPathForScope(
   return path.join(ctx.product_dir, "sources.yaml");
 }
 
-function relForMd(scope: string, filename: string): string {
+export function sourceDirForScope(ctx: ProductContext, scope: string): string {
+  const dataDir = path.resolve(env.PRODUCT_MCP_DATA_DIR);
+  if (scope === "category") {
+    return path.join(dataDir, ctx.category, ctx.vendor, "source");
+  }
+  if (scope === "line") {
+    return path.join(dataDir, ctx.category, ctx.vendor, ctx.product_line, "source");
+  }
+  return path.join(ctx.product_dir, "source");
+}
+
+export function relForMd(scope: string, filename: string): string {
   if (scope === "category") return `../../source/${filename}`;
   if (scope === "line") return `../source/${filename}`;
   return `source/${filename}`;
@@ -729,7 +739,7 @@ export async function manualUpload(
 
   const scope = input.scope ?? "own";
   const filename = input.filename ?? stableFilenameFor(input.docType);
-  const sourceDir = path.join(ctx.product_dir, "source");
+  const sourceDir = sourceDirForScope(ctx, scope);
   fs.mkdirSync(sourceDir, { recursive: true });
   const targetAbs = path.join(sourceDir, filename);
   const tmp = `${targetAbs}.tmp-${process.pid}-${Date.now()}`;
diff --git a/tests/unit/pipeline-sources.test.ts b/tests/unit/pipeline-sources.test.ts
new file mode 100644
index 0000000..1e3a110
--- /dev/null
+++ b/tests/unit/pipeline-sources.test.ts
@@ -0,0 +1,53 @@
+import path from "node:path";
+import { describe, expect, it } from "vitest";
+import { relForMd, sourceDirForScope, type ProductContext } from "@/lib/pipeline/sources";
+
+function productContext(root: string): ProductContext {
+  return {
+    vendor: "dell",
+    product_line: "poweredge",
+    category: "server",
+    slug: "r770",
+    canonical_name: "Dell PowerEdge R770",
+    product_dir: path.join(root, "server", "dell", "poweredge", "r770"),
+    product_md: path.join(root, "server", "dell", "poweredge", "r770", "r770.md"),
+  };
+}
+
+describe("scoped source paths", () => {
+  it("stores own-scope files in the product source directory", () => {
+    const root = path.resolve(process.env.PRODUCT_MCP_DATA_DIR ?? "./data/sample");
+    const ctx = productContext(root);
+
+    expect(sourceDirForScope(ctx, "own")).toBe(
+      path.join(root, "server", "dell", "poweredge", "r770", "source"),
+    );
+    expect(relForMd("own", "spec-sheet.pdf")).toBe("source/spec-sheet.pdf");
+  });
+
+  it("stores line-scope files where ../source manifest paths resolve", () => {
+    const root = path.resolve(process.env.PRODUCT_MCP_DATA_DIR ?? "./data/sample");
+    const ctx = productContext(root);
+    const filename = "technical-guide.pdf";
+
+    expect(sourceDirForScope(ctx, "line")).toBe(
+      path.join(root, "server", "dell", "poweredge", "source"),
+    );
+    expect(path.resolve(ctx.product_dir, relForMd("line", filename))).toBe(
+      path.join(root, "server", "dell", "poweredge", "source", filename),
+    );
+  });
+
+  it("stores category-scope files where ../../source manifest paths resolve", () => {
+    const root = path.resolve(process.env.PRODUCT_MCP_DATA_DIR ?? "./data/sample");
+    const ctx = productContext(root);
+    const filename = "portfolio.pdf";
+
+    expect(sourceDirForScope(ctx, "category")).toBe(
+      path.join(root, "server", "dell", "source"),
+    );
+    expect(path.resolve(ctx.product_dir, relForMd("category", filename))).toBe(
+      path.join(root, "server", "dell", "source", filename),
+    );
+  });
+});