feat(FN-3037): add focus-visible styling to AgentLogViewer log action butto

Adds `focus-visible` styling to action buttons in the AgentLogViewer component, improving keyboard accessibility for interactive button elements.

Fusion-Task-Id: FN-3037

packages/engine/src/__tests__/agent-logger.test.ts

@@ -327,7 +327,23 @@ describe("AgentLogger", () => {
     expect(store.appendAgentLog).toHaveBeenCalledWith("FN-016", "Read", "tool_error", "file not found", "executor");
   });
 
-  it("truncates long tool results to 500 chars", async () => {
+  it("preserves long tool errors without truncation", async () => {
+    const store = createMockStore();
+    const logger = new AgentLogger({
+      store,
+      taskId: "FN-016B",
+      agent: "executor",
+    });
+
+    const longError = "error:" + "y".repeat(1200);
+    logger.onToolEnd("Read", true, longError);
+    await vi.advanceTimersByTimeAsync(0);
+
+    const call = (store.appendAgentLog as ReturnType<typeof vi.fn>).mock.calls[0];
+    expect(call[3]).toBe(longError);
+  });
+
+  it("preserves long tool results without truncation", async () => {
     const store = createMockStore();
     const logger = new AgentLogger({
       store,
@@ -340,7 +356,7 @@ describe("AgentLogger", () => {
     await vi.advanceTimersByTimeAsync(0);
 
     const call = (store.appendAgentLog as ReturnType<typeof vi.fn>).mock.calls[0];
-    expect(call[3]).toBe("x".repeat(500) + "…");
+    expect(call[3]).toBe(longResult);
   });
 
   it("handles undefined result in onToolEnd", async () => {

packages/engine/src/agent-logger.ts

@@ -160,14 +160,13 @@ export class AgentLogger {
    *
    * @param name - The tool name
    * @param isError - Whether the tool execution resulted in an error
-   * @param result - Optional result value (truncated for persistence)
+   * @param result - Optional result value (persisted in full)
    */
   onToolEnd(name: string, isError: boolean, result?: unknown): void {
     const type = isError ? "tool_error" : "tool_result";
     let detail: string | undefined;
     if (result !== undefined && result !== null) {
-      const str = typeof result === "string" ? result : JSON.stringify(result);
-      detail = str.length > 500 ? str.slice(0, 500) + "…" : str;
+      detail = typeof result === "string" ? result : JSON.stringify(result);
     }
     this.store.appendAgentLog(this.taskId, name, type, detail, this.agent).catch((err) => {
       this.log.warn(`Failed to log tool end "${name}" (${type}) for ${this.taskId}: ${err instanceof Error ? err.message : String(err)}`);