diff --git a/packages/core/src/__tests__/agent-companies-parser.test.ts b/packages/core/src/__tests__/agent-companies-parser.test.ts
index 541bc00f57..af0a56ad61 100644
--- a/packages/core/src/__tests__/agent-companies-parser.test.ts
+++ b/packages/core/src/__tests__/agent-companies-parser.test.ts
@@ -659,6 +659,121 @@ name: Nested Archive CEO
     });
   });
 
+  describe("lazy-load isolation", () => {
+    it("does not load extract-zip or tar for pure manifest helpers", async () => {
+      const extractZipModuleFactory = vi.fn(() => ({
+        default: vi.fn(async () => undefined),
+      }));
+      const tarModuleFactory = vi.fn(() => ({
+        x: vi.fn(async () => undefined),
+      }));
+
+      vi.resetModules();
+      vi.doMock("extract-zip", extractZipModuleFactory);
+      vi.doMock("tar", tarModuleFactory);
+
+      const parserModule = await import("../agent-companies-parser.js");
+
+      const parsed = parserModule.parseYamlFrontmatter(`---
+name: Pure Helper
+---
+Body`);
+      expect(parsed.frontmatter.name).toBe("Pure Helper");
+      expect(parsed.body).toBe("Body");
+
+      const manifest = parserModule.parseAgentManifest(`---
+name: Pure Agent
+skills:
+  - review
+---
+Keep things tidy.`);
+      expect(manifest.name).toBe("Pure Agent");
+
+      const prepared = parserModule.prepareAgentCompaniesImport({
+        company: { name: "Pure Company" },
+        agents: [{ name: "Pure Agent", title: "Reviewer", instructionBody: "Keep things tidy." }],
+        teams: [],
+        projects: [],
+        tasks: [],
+      });
+      expect(prepared.items).toHaveLength(1);
+
+      const converted = parserModule.convertAgentCompanies({
+        company: { name: "Pure Company" },
+        agents: [{ name: "Pure Agent", title: "Reviewer", instructionBody: "Keep things tidy." }],
+        teams: [],
+        projects: [],
+        tasks: [],
+        skills: [],
+      });
+      expect(converted.inputs).toHaveLength(1);
+
+      expect(extractZipModuleFactory).not.toHaveBeenCalled();
+      expect(tarModuleFactory).not.toHaveBeenCalled();
+
+      vi.doUnmock("extract-zip");
+      vi.doUnmock("tar");
+      vi.resetModules();
+    });
+
+    it("dynamically imports extract-zip when parsing zip archives", async () => {
+      const extractZip = vi.fn(async (_archivePath: string, options: { dir: string }) => {
+        writeTextFile(join(options.dir, "zip-company", "COMPANY.md"), `---\nname: Mock Zip Company\n---`);
+        writeTextFile(join(options.dir, "zip-company", "agents", "ceo", "AGENTS.md"), `---\nname: Mock Zip CEO\n---`);
+      });
+      const extractZipModuleFactory = vi.fn(() => ({ default: extractZip }));
+
+      vi.resetModules();
+      vi.doMock("extract-zip", extractZipModuleFactory);
+
+      const parserModule = await import("../agent-companies-parser.js");
+      const root = createTempDir();
+      const archivePath = join(root, "company.zip");
+      writeFileSync(archivePath, Buffer.from("placeholder zip contents"));
+
+      const pkg = await parserModule.parseCompanyArchive(archivePath);
+      expect(pkg.company?.name).toBe("Mock Zip Company");
+      expect(pkg.agents[0]?.name).toBe("Mock Zip CEO");
+      expect(extractZipModuleFactory).toHaveBeenCalledTimes(1);
+      expect(extractZip).toHaveBeenCalledTimes(1);
+      expect(extractZip).toHaveBeenCalledWith(
+        archivePath,
+        expect.objectContaining({ dir: expect.any(String) }),
+      );
+
+      vi.doUnmock("extract-zip");
+      vi.resetModules();
+    });
+
+    it("dynamically imports tar when parsing tgz archives", async () => {
+      const tarExtract = vi.fn(async (options: { file: string; cwd: string }) => {
+        writeTextFile(join(options.cwd, "tar-company", "COMPANY.md"), `---\nname: Mock Tar Company\n---`);
+        writeTextFile(join(options.cwd, "tar-company", "agents", "ceo", "AGENTS.md"), `---\nname: Mock Tar CEO\n---`);
+      });
+      const tarModuleFactory = vi.fn(() => ({ x: tarExtract }));
+
+      vi.resetModules();
+      vi.doMock("tar", tarModuleFactory);
+
+      const parserModule = await import("../agent-companies-parser.js");
+      const root = createTempDir();
+      const archivePath = join(root, "company.tgz");
+      writeFileSync(archivePath, Buffer.from("placeholder tgz contents"));
+
+      const pkg = await parserModule.parseCompanyArchive(archivePath);
+      expect(pkg.company?.name).toBe("Mock Tar Company");
+      expect(pkg.agents[0]?.name).toBe("Mock Tar CEO");
+      expect(tarModuleFactory).toHaveBeenCalledTimes(1);
+      expect(tarExtract).toHaveBeenCalledTimes(1);
+      expect(tarExtract).toHaveBeenCalledWith(
+        expect.objectContaining({ file: archivePath, cwd: expect.any(String) }),
+      );
+
+      vi.doUnmock("tar");
+      vi.resetModules();
+    });
+  });
+
   describe("conversion", () => {
     it("maps AgentManifest to AgentCreateInput", () => {
       const input = agentManifestToAgentCreateInput({
diff --git a/packages/core/src/agent-companies-parser.ts b/packages/core/src/agent-companies-parser.ts
index f1a07e42ef..afb50e151e 100644
--- a/packages/core/src/agent-companies-parser.ts
+++ b/packages/core/src/agent-companies-parser.ts
@@ -8,8 +8,6 @@ import { existsSync, mkdtempSync, readdirSync, readFileSync, rmSync, statSync }
 import { tmpdir } from "node:os";
 import { isAbsolute, join, normalize, resolve } from "node:path";
 
-import extractZip from "extract-zip";
-import { x as tarExtract } from "tar";
 import { parse as parseYaml } from "yaml";
 
 import type {
@@ -481,6 +479,7 @@ function resolveExtractionRoot(tempDir: string): string {
 }
 
 async function extractTarArchive(archivePath: string, outputDir: string): Promise<void> {
+  const { x: tarExtract } = await import("tar");
   await tarExtract({
     file: archivePath,
     cwd: outputDir,
@@ -530,6 +529,7 @@ export async function parseCompanyArchive(
     if (resolvedArchivePath.endsWith(".tar.gz") || resolvedArchivePath.endsWith(".tgz")) {
       await extractTarArchive(resolvedArchivePath, tempDir);
     } else if (resolvedArchivePath.endsWith(".zip")) {
+      const extractZip = (await import("extract-zip")).default;
       await extractZip(resolvedArchivePath, { dir: tempDir });
     } else {
       throw new AgentCompaniesParseError(
diff --git a/packages/desktop/electron-builder.yml b/packages/desktop/electron-builder.yml
index 285df9e51f..94d0878f21 100644
--- a/packages/desktop/electron-builder.yml
+++ b/packages/desktop/electron-builder.yml
@@ -7,6 +7,12 @@ directories:
   buildResources: src/icons
 
 files:
+  # pnpm installs workspace/runtime deps as symlinked package entries backed by the
+  # virtual store. These flat node_modules/X/**/* patterns only work when electron-builder
+  # follows the symlink chain from the published package entry, so every @fusion/core
+  # runtime dependency group that the desktop app can load must be listed here.
+  # If @fusion/core gains a new runtime dependency, add it (and any required leaf deps)
+  # here or packaged desktop builds can fail at startup/runtime with missing-module errors.
   - dist/**/*
   - package.json
   - node_modules/@fusion/core/**/*
@@ -29,6 +35,44 @@ files:
   - node_modules/debug/**/*
   - node_modules/ms/**/*
   - node_modules/sax/**/*
+  # @fusion/core archive parsing deps
+  - node_modules/extract-zip/**/*
+  - node_modules/get-stream/**/*
+  - node_modules/pump/**/*
+  - node_modules/end-of-stream/**/*
+  - node_modules/once/**/*
+  - node_modules/wrappy/**/*
+  - node_modules/yauzl/**/*
+  - node_modules/fd-slicer/**/*
+  - node_modules/pend/**/*
+  - node_modules/buffer-crc32/**/*
+  - node_modules/tar/**/*
+  - node_modules/@isaacs/fs-minipass/**/*
+  - node_modules/chownr/**/*
+  - node_modules/minipass/**/*
+  - node_modules/minizlib/**/*
+  - node_modules/yallist/**/*
+  - node_modules/yaml/**/*
+  # @fusion/core scheduling/automation deps
+  - node_modules/cron-parser/**/*
+  - node_modules/luxon/**/*
+  # @fusion/core discovery/system deps
+  - node_modules/bonjour-service/**/*
+  - node_modules/fast-deep-equal/**/*
+  - node_modules/multicast-dns/**/*
+  - node_modules/dns-packet/**/*
+  - node_modules/thunky/**/*
+  - node_modules/@leichtgewicht/ip-codec/**/*
+  - node_modules/check-disk-space/**/*
+  # @fusion/core optional docker runtime deps
+  - node_modules/dockerode/**/*
+  - node_modules/@balena/dockerignore/**/*
+  - node_modules/@grpc/grpc-js/**/*
+  - node_modules/@grpc/proto-loader/**/*
+  - node_modules/docker-modem/**/*
+  - node_modules/protobufjs/**/*
+  - node_modules/tar-fs/**/*
+  - node_modules/uuid/**/*
 
 asarUnpack:
   - node_modules/better-sqlite3/**/*