diff --git a/packages/core-internal/src/services/code-navigation-service.test.ts b/packages/core-internal/src/services/code-navigation-service.test.ts
index 3d5bb5f4..bc2103c8 100644
--- a/packages/core-internal/src/services/code-navigation-service.test.ts
+++ b/packages/core-internal/src/services/code-navigation-service.test.ts
@@ -14,6 +14,7 @@ import {
   CodeNavigationIndexingError,
   CodeNavigationRefNotFoundError,
   CodeNavigationServiceImpl,
+  CodeNavigationTargetNotFoundError,
 } from "./code-navigation-service.js";
 import { createMockTokenProvider } from "./test-helpers.js";
 
@@ -1067,6 +1068,50 @@ describe("CodeNavigationServiceImpl", () => {
     }
   });
 
+  it("classifies GraphQL REPOSITORY_NOT_FOUND as target not found with repository details", async () => {
+    mockFetch(() =>
+      Promise.resolve(
+        new Response(
+          JSON.stringify({
+            errors: [
+              {
+                message:
+                  "Repository not found or inaccessible: https://github.com/acme/missing.",
+                extensions: {
+                  code: "REPOSITORY_NOT_FOUND",
+                  retryable: false,
+                  repo_url: "https://github.com/acme/missing",
+                  git_ref: "main",
+                },
+              },
+            ],
+          }),
+          { status: 200 },
+        ),
+      ),
+    );
+    const service = new CodeNavigationServiceImpl(
+      BASE_URL,
+      createMockTokenProvider(),
+    );
+
+    try {
+      await service.search({
+        targets: [
+          { repoUrl: "https://github.com/acme/missing", gitRef: "main" },
+        ],
+        query: "router middleware",
+      });
+      throw new Error("expected REPOSITORY_NOT_FOUND");
+    } catch (error) {
+      expect(error).toBeInstanceOf(CodeNavigationTargetNotFoundError);
+      expect(error).not.toBeInstanceOf(CodeNavigationBackendError);
+      const typed = error as CodeNavigationTargetNotFoundError;
+      expect(typed.repoUrl).toBe("https://github.com/acme/missing");
+      expect(typed.requestedRef).toBe("main");
+    }
+  });
+
   it("classifies GraphQL schema mismatch as backend protocol error", async () => {
     mockFetch(() =>
       Promise.resolve(
diff --git a/packages/core-internal/src/services/code-navigation-service.ts b/packages/core-internal/src/services/code-navigation-service.ts
index 7f5959da..b80deccc 100644
--- a/packages/core-internal/src/services/code-navigation-service.ts
+++ b/packages/core-internal/src/services/code-navigation-service.ts
@@ -539,6 +539,8 @@ export class CodeNavigationTargetNotFoundError extends Error {
   constructor(
     message: string,
     public readonly availableVersions?: AvailableVersion[],
+    public readonly repoUrl?: string,
+    public readonly requestedRef?: string,
   ) {
     super(message);
     this.name = "CodeNavigationTargetNotFoundError";
@@ -2015,16 +2017,8 @@ export class CodeNavigationServiceImpl implements CodeNavigationService {
       case "REF_NOT_FOUND":
         return new CodeNavigationRefNotFoundError(
           message,
-          typeof extensions?.repo_url === "string"
-            ? extensions.repo_url
-            : typeof extensions?.repoUrl === "string"
-              ? extensions.repoUrl
-              : undefined,
-          typeof extensions?.git_ref === "string"
-            ? extensions.git_ref
-            : typeof extensions?.gitRef === "string"
-              ? extensions.gitRef
-              : undefined,
+          parseGraphQLRepoUrl(extensions),
+          parseGraphQLGitRef(extensions),
           parseAvailableRefs(extensions),
           parseSuggestedRefs(extensions),
         );
@@ -2034,6 +2028,14 @@ export class CodeNavigationServiceImpl implements CodeNavigationService {
       case "NO_REPOSITORY_URL":
         return new CodeNavigationTargetNotFoundError(message);
 
+      case "REPOSITORY_NOT_FOUND":
+        return new CodeNavigationTargetNotFoundError(
+          message,
+          undefined,
+          parseGraphQLRepoUrl(extensions),
+          parseGraphQLGitRef(extensions),
+        );
+
       case "FILE_NOT_FOUND":
         return new CodeNavigationFileNotFoundError(
           message,
@@ -2753,6 +2755,26 @@ function parseSuggestedRefs(
   return parseAvailableArtifacts(raw);
 }
 
+function parseGraphQLRepoUrl(
+  extensions: Record<string, unknown> | undefined,
+): string | undefined {
+  return typeof extensions?.repo_url === "string"
+    ? extensions.repo_url
+    : typeof extensions?.repoUrl === "string"
+      ? extensions.repoUrl
+      : undefined;
+}
+
+function parseGraphQLGitRef(
+  extensions: Record<string, unknown> | undefined,
+): string | undefined {
+  return typeof extensions?.git_ref === "string"
+    ? extensions.git_ref
+    : typeof extensions?.gitRef === "string"
+      ? extensions.gitRef
+      : undefined;
+}
+
 function parseTargetResolution(
   extensions: Record<string, unknown> | undefined,
 ): TargetResolution | undefined {
diff --git a/packages/mcp/src/shared/code-navigation-error-map.test.ts b/packages/mcp/src/shared/code-navigation-error-map.test.ts
index b986e136..76090d24 100644
--- a/packages/mcp/src/shared/code-navigation-error-map.test.ts
+++ b/packages/mcp/src/shared/code-navigation-error-map.test.ts
@@ -71,6 +71,24 @@ describe("mapCodeNavigationError", () => {
     });
   });
 
+  it("classifies repository CodeNavigationTargetNotFoundError with repository details", () => {
+    const err = new CodeNavigationTargetNotFoundError(
+      "Repository not found or inaccessible",
+      undefined,
+      "https://github.com/acme/missing",
+      "main",
+    );
+    expect(mapCodeNavigationError(err)).toEqual({
+      code: "NOT_FOUND",
+      message: "Repository not found or inaccessible",
+      retryable: false,
+      details: {
+        repoUrl: "https://github.com/acme/missing",
+        requestedRef: "main",
+      },
+    });
+  });
+
   it("classifies CodeNavigationVersionNotFoundError as VERSION_NOT_FOUND with structured details", () => {
     const err = new CodeNavigationVersionNotFoundError(
       'No version of npm/express matches "4". Available versions: 5.2.1, 5.1.0. Try: express@5.2.1.',
@@ -297,6 +315,22 @@ describe("mapCodeNavigationError", () => {
     });
   });
 
+  it("classifies CodeNavigationBackendError with REPOSITORY_NOT_FOUND as NOT_FOUND", () => {
+    const err = new CodeNavigationBackendError(
+      "Repository not found or inaccessible",
+      undefined,
+      "REPOSITORY_NOT_FOUND",
+      false,
+    );
+
+    expect(mapCodeNavigationError(err)).toEqual({
+      code: "NOT_FOUND",
+      message: "Repository not found or inaccessible",
+      retryable: false,
+      details: { graphqlCode: "REPOSITORY_NOT_FOUND" },
+    });
+  });
+
   it("classifies CodeNavigationBackendError with UPSTREAM_ERROR as BACKEND_ERROR (retryable default)", () => {
     const err = new CodeNavigationBackendError(
       "Upstream failed",
diff --git a/packages/mcp/src/shared/code-navigation-error-map.ts b/packages/mcp/src/shared/code-navigation-error-map.ts
index 2e5a5d8e..e29ffe5b 100644
--- a/packages/mcp/src/shared/code-navigation-error-map.ts
+++ b/packages/mcp/src/shared/code-navigation-error-map.ts
@@ -141,13 +141,17 @@ function classify(error: unknown): MappedError {
     };
   }
   if (error instanceof CodeNavigationTargetNotFoundError) {
+    const details: MappedErrorDetails = {};
+    if (error.availableVersions && error.availableVersions.length > 0) {
+      details.availableVersions = error.availableVersions;
+    }
+    if (error.repoUrl) details.repoUrl = error.repoUrl;
+    if (error.requestedRef) details.requestedRef = error.requestedRef;
     return {
       code: "NOT_FOUND",
       message: error.message,
       retryable: false,
-      details: error.availableVersions
-        ? { availableVersions: error.availableVersions }
-        : undefined,
+      details: Object.keys(details).length > 0 ? details : undefined,
     };
   }
   if (error instanceof CodeNavigationRefNotFoundError) {
@@ -313,6 +317,8 @@ function classifyBackendError(error: CodeNavigationBackendError): MappedError {
       return build("TIMEOUT", true);
     case "RATE_LIMITED":
       return build("RATE_LIMITED", true);
+    case "REPOSITORY_NOT_FOUND":
+      return build("NOT_FOUND", false);
     case "REF_NOT_FOUND":
       return build("REF_NOT_FOUND", false);
     case "UPSTREAM_ERROR":
diff --git a/packages/mcp/src/shared/unified-search-response.test.ts b/packages/mcp/src/shared/unified-search-response.test.ts
index 01babcbc..3172fddc 100644
--- a/packages/mcp/src/shared/unified-search-response.test.ts
+++ b/packages/mcp/src/shared/unified-search-response.test.ts
@@ -1,6 +1,7 @@
 import { describe, expect, it } from "bun:test";
 import {
   CodeNavigationRefNotFoundError,
+  CodeNavigationTargetNotFoundError,
   type UnifiedSearchOutcome,
   type UnifiedSearchParams,
 } from "@githits/core-internal";
@@ -1100,6 +1101,27 @@ describe("buildUnifiedSearchErrorPayload", () => {
       },
     });
   });
+
+  it("includes repository NOT_FOUND details for missing repositories", () => {
+    const payload = buildUnifiedSearchErrorPayload(
+      new CodeNavigationTargetNotFoundError(
+        "Repository not found or inaccessible",
+        undefined,
+        "https://github.com/acme/missing",
+        "main",
+      ),
+    );
+
+    expect(payload).toEqual({
+      error: "Repository not found or inaccessible",
+      code: "NOT_FOUND",
+      retryable: false,
+      details: {
+        repoUrl: "https://github.com/acme/missing",
+        requestedRef: "main",
+      },
+    });
+  });
 });
 
 describe("buildUnifiedSearchStatusPayload", () => {
diff --git a/scripts/validate-public-packages.ts b/scripts/validate-public-packages.ts
index b816b064..2bf655b8 100644
--- a/scripts/validate-public-packages.ts
+++ b/scripts/validate-public-packages.ts
@@ -16,7 +16,7 @@ interface PackFile {
 }
 
 interface PackResult {
-  filename: string;
+  filename?: string;
   files?: PackFile[];
 }
 
@@ -196,10 +196,23 @@ async function packPackage(
   );
   const packResults = JSON.parse(output) as PackResult[];
   const filename = packResults[0]?.filename;
-  if (!filename) {
-    throw new Error(`npm pack did not return a filename for ${packageInfo.id}`);
+  if (filename) {
+    return join(packDirectory, basename(filename));
   }
-  return join(packDirectory, basename(filename));
+
+  const tarballs = (await readdir(packDirectory)).filter((entry) =>
+    entry.endsWith(".tgz"),
+  );
+  if (tarballs.length !== 1) {
+    throw new Error(
+      `npm pack did not return a filename for ${packageInfo.id} and created ${tarballs.length} tarballs`,
+    );
+  }
+  const tarball = tarballs[0];
+  if (!tarball) {
+    throw new Error(`npm pack did not create a tarball for ${packageInfo.id}`);
+  }
+  return join(packDirectory, tarball);
 }
 
 async function extractPackage(