feat(FN-4015): classify and recover from stale module-resolution incidents

Merges FN-4015 to add stale module-resolution incident detection and self-healing in the engine (`transient-error-detector.ts`, `self-healing.ts`) with mobile regression coverage for the shared `AgentErrorDetailsModal` layout.

Fusion-Task-Id: FN-4015

packages/dashboard/app/components/__tests__/AgentErrorDetailsModal.test.tsx

@@ -0,0 +1,68 @@
+import { describe, expect, it, vi, beforeEach, afterEach } from "vitest";
+import { render, screen, waitFor } from "@testing-library/react";
+import userEvent from "@testing-library/user-event";
+import { AgentErrorDetailsModal, AgentErrorIndicator } from "../AgentErrorDetailsModal";
+
+const issueContext = {
+  surface: "AgentsView",
+  agentId: "agent-1",
+  agentName: "Test Agent",
+  agentState: "error",
+  runId: "run-1",
+  taskId: "FN-1",
+  timestamp: "2026-01-01T00:00:00.000Z",
+};
+
+describe("AgentErrorDetailsModal", () => {
+  const originalClipboard = navigator.clipboard;
+  const openSpy = vi.spyOn(window, "open").mockImplementation(() => null);
+  beforeEach(() => {
+    Object.defineProperty(navigator, "clipboard", {
+      value: { writeText: vi.fn().mockResolvedValue(undefined) },
+      configurable: true,
+    });
+    openSpy.mockClear();
+  });
+
+  afterEach(() => {
+    Object.defineProperty(navigator, "clipboard", { value: originalClipboard, configurable: true });
+  });
+
+  it("does not render when closed", () => {
+    const { container } = render(<AgentErrorDetailsModal open={false} onClose={vi.fn()} errorText="boom" issueContext={issueContext} />);
+    expect(container).toBeEmptyDOMElement();
+  });
+
+  it("renders long error text in scrollable error region", () => {
+    render(<AgentErrorDetailsModal open={true} onClose={vi.fn()} errorText={"stderr\n".repeat(200)} issueContext={issueContext} />);
+    const errorRegion = document.querySelector(".agent-error-modal__error");
+    expect(errorRegion).toBeInTheDocument();
+    expect(errorRegion).toHaveTextContent("stderr");
+  });
+
+  it("copies error text", async () => {
+    const user = userEvent.setup();
+    render(<AgentErrorDetailsModal open={true} onClose={vi.fn()} errorText="copy me" issueContext={issueContext} />);
+
+    await user.click(screen.getByRole("button", { name: "Copy error to clipboard" }));
+    await waitFor(() => {
+      expect(screen.getByRole("button", { name: "Copied error to clipboard" })).toBeInTheDocument();
+    });
+  });
+
+  it("opens github report link", async () => {
+    const user = userEvent.setup();
+    render(<AgentErrorDetailsModal open={true} onClose={vi.fn()} errorText="report me" issueContext={issueContext} />);
+
+    await user.click(screen.getByRole("link", { name: /report on github/i }));
+    expect(openSpy).toHaveBeenCalledTimes(1);
+    expect(openSpy.mock.calls[0]?.[0]).toContain("https://github.com/Runfusion/Fusion/issues/new?");
+  });
+
+  it("AgentErrorIndicator opens shared modal", async () => {
+    const user = userEvent.setup();
+    render(<AgentErrorIndicator errorText="indicator error" issueContext={issueContext} />);
+    await user.click(screen.getByRole("button", { name: "Open error details" }));
+    expect(screen.getByRole("dialog", { name: "Agent error details" })).toBeInTheDocument();
+  });
+});

packages/dashboard/app/components/__tests__/agent-modals-mobile.test.tsx

@@ -394,14 +394,15 @@ describe("agent modal mobile CSS structure", () => {
   });
 
   describe("AgentErrorDetailsModal", () => {
-    it("mobile rules constrain modal to viewport height", () => {
+    it("mobile rules let modal fill the fullscreen container without double viewport clipping", () => {
       const styles = readStyles();
-      const modalRuleMatch = styles.match(/@media \(max-width: 768px\)[\s\S]*?\.agent-error-modal\s*\{[^}]+\}/);
+      const modalRuleMatch = styles.match(/@media\s*\(max-width:\s*768px\)\s*\{\s*\.agent-error-modal\s*\{[^}]+\}/);
       expect(modalRuleMatch).toBeTruthy();
       const modalRule = modalRuleMatch![0];
 
-      expect(modalRule).toContain("height: 100dvh");
-      expect(modalRule).toContain("max-height: 100dvh");
+      expect(modalRule).toContain("height: 100%");
+      expect(modalRule).toContain("max-height: 100%");
+      expect(modalRule).toContain("min-height: 0");
       expect(modalRule).toContain("width: 100%");
       expect(modalRule).toContain("max-width: 100%");
     });
@@ -414,6 +415,7 @@ describe("agent modal mobile CSS structure", () => {
 
       expect(styles).toMatch(/@media \(max-width: 768px\)[\s\S]*?\.agent-error-modal__error\s*\{[^}]*max-height:\s*none;[^}]*\}/);
       expect(styles).toMatch(/@media \(max-width: 768px\)[\s\S]*?\.agent-error-modal__error\s*\{[^}]*-webkit-overflow-scrolling:\s*touch;[^}]*\}/);
+      expect(styles).toMatch(/@media \(max-width: 768px\)[\s\S]*?\.agent-error-modal__error\s*\{[^}]*overscroll-behavior:\s*contain;[^}]*\}/);
     });
   });
 

packages/dashboard/app/components/__tests__/core-modals-mobile.test.tsx

@@ -298,22 +298,26 @@ describe("core modals mobile css coverage", () => {
     expect(fullscreenBlockMatch![0]).toContain("max-height: unset");
   });
 
-  it("AgentErrorDetailsModal: mobile uses viewport-sized modal with inner scrolling log region", () => {
+  it("AgentErrorDetailsModal: mobile fills fullscreen container and keeps inner scrolling log region", () => {
     const css = loadAllAppCss();
     const mobileBlock = getMainMobileBlock(css);
 
     const modalRuleMatch = mobileBlock.match(/\.agent-error-modal\s*\{[^}]+\}/s);
     expect(modalRuleMatch).not.toBeNull();
-    expect(modalRuleMatch![0]).toContain("height: 100dvh");
-    expect(modalRuleMatch![0]).toContain("max-height: 100dvh");
+    expect(modalRuleMatch![0]).toContain("height: 100%");
+    expect(modalRuleMatch![0]).toContain("max-height: 100%");
+    expect(modalRuleMatch![0]).toContain("min-height: 0");
 
     const contentRuleMatch = css.match(/\.agent-error-modal__content\s*\{[^}]+\}/s);
     expect(contentRuleMatch).not.toBeNull();
     expect(contentRuleMatch![0]).toContain("overflow: hidden");
+    expect(contentRuleMatch![0]).toContain("display: flex");
 
     const errorRuleMatch = mobileBlock.match(/\.agent-error-modal__error\s*\{[^}]+\}/s);
     expect(errorRuleMatch).not.toBeNull();
+    expect(errorRuleMatch![0]).toContain("max-height: none");
     expect(errorRuleMatch![0]).toContain("-webkit-overflow-scrolling: touch");
+    expect(errorRuleMatch![0]).toContain("overscroll-behavior: contain");
   });
 
   it("NewTaskModal: quick fields buttons meet 36px touch target on mobile", () => {