feat: add LoRA syntax utilities and comprehensive test suite, fixes #600

- Implement core LoRA syntax manipulation functions including:
  - applyLoraValuesToText for updating LoRA strengths and clip values
  - normalizeStrengthValue for consistent numeric formatting
  - shouldIncludeClipStrength for clip strength inclusion logic
  - cleanupLoraSyntax for text normalization
  - debounce utility for input handling

- Add comprehensive test suite covering all utility functions
- Include edge cases for clip strength handling, numeric formatting, and syntax cleanup
- Support both basic and expanded LoRA syntax formats with proper value preservation
- Enable debounced input synchronization for better performance

The utilities provide robust handling of LoRA syntax patterns while maintaining compatibility with existing ComfyUI workflows.

tests/frontend/managers/loraSyntaxUtils.test.js

@@ -0,0 +1,113 @@
+import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
+import { applyLoraValuesToText, debounce, __testables } from "../../../web/comfyui/lora_syntax_utils.js";
+
+const { normalizeStrengthValue, shouldIncludeClipStrength, cleanupLoraSyntax } = __testables();
+
+describe("applyLoraValuesToText", () => {
+  it("updates existing LoRA strengths", () => {
+    const original = "<lora:StrengthTest:0.50>";
+    const result = applyLoraValuesToText(original, [
+      { name: "StrengthTest", strength: 0.8 }
+    ]);
+
+    expect(result).toBe("<lora:StrengthTest:0.80>");
+  });
+
+  it("updates clip strength while preserving syntax", () => {
+    const original = "<lora:ClipTest:1.00:0.50>";
+    const result = applyLoraValuesToText(original, [
+      { name: "ClipTest", strength: 1, clipStrength: 0.75 }
+    ]);
+
+    expect(result).toBe("<lora:ClipTest:1.00:0.75>");
+  });
+
+  it("appends missing LoRAs to the input text", () => {
+    const original = "<lora:Present:0.70>";
+    const result = applyLoraValuesToText(original, [
+      { name: "Present", strength: 0.7 },
+      { name: "Additional", strength: 0.4 }
+    ]);
+
+    expect(result).toBe("<lora:Present:0.70> <lora:Additional:0.40>");
+  });
+
+  it("keeps clip entry when expanded even if values match", () => {
+    const original = "<lora:Expanded:1.00>";
+    const result = applyLoraValuesToText(original, [
+      { name: "Expanded", strength: 1, clipStrength: 1, expanded: true }
+    ]);
+
+    expect(result).toBe("<lora:Expanded:1.00:1.00>");
+  });
+});
+
+describe("normalizeStrengthValue", () => {
+  it("defaults to 1.00 for non-numeric input", () => {
+    expect(normalizeStrengthValue("foo")).toBe("1.00");
+  });
+
+  it("formats numeric input to two decimals", () => {
+    expect(normalizeStrengthValue(0.3333)).toBe("0.33");
+  });
+});
+
+describe("shouldIncludeClipStrength", () => {
+  it("returns true when clip differs", () => {
+    expect(
+      shouldIncludeClipStrength({ strength: 1, clipStrength: 0.8 }, undefined)
+    ).toBe(true);
+  });
+
+  it("returns true when expanded despite equal values", () => {
+    expect(
+      shouldIncludeClipStrength({ strength: 1, clipStrength: 1, expanded: true }, undefined)
+    ).toBe(true);
+  });
+
+  it("falls back to existing syntax when clip missing", () => {
+    expect(shouldIncludeClipStrength({}, "0.7")).toBe(true);
+  });
+});
+
+describe("cleanupLoraSyntax", () => {
+  it("collapses whitespace and stray commas", () => {
+    expect(cleanupLoraSyntax("  <lora:A:1.00>  , ," )).toBe("<lora:A:1.00>");
+  });
+});
+
+describe("debounce", () => {
+  beforeEach(() => {
+    vi.useFakeTimers();
+  });
+
+  afterEach(() => {
+    vi.useRealTimers();
+  });
+
+  it("delays execution and keeps latest arguments", () => {
+    const spy = vi.fn();
+    const debounced = debounce(spy, 100);
+
+    debounced("first");
+    debounced("second");
+
+    expect(spy).not.toHaveBeenCalled();
+
+    vi.advanceTimersByTime(100);
+
+    expect(spy).toHaveBeenCalledTimes(1);
+    expect(spy).toHaveBeenCalledWith("second");
+  });
+
+  it("flushes pending calls immediately", () => {
+    const spy = vi.fn();
+    const debounced = debounce(spy, 200);
+
+    debounced("queued");
+    debounced.flush();
+
+    expect(spy).toHaveBeenCalledTimes(1);
+    expect(spy).toHaveBeenCalledWith("queued");
+  });
+});