gen-cards: regenerate Use-it block

README.md

@@ -25,6 +25,47 @@ paradigm, running on-device on Apple Silicon.
 - **Runtime:** Apple Core AI (`coreai-core`), GPU
 
 <!-- gen-cards:use-it begin id=llada-8b (managed by scripts/gen-cards — edit cards.json / QuickStart.swift, not this block) -->
+## Use it
+
+▶️ **Run it (source)** — the [DiffuseChat runner](https://github.com/john-rocky/coreai-kit/tree/main/Examples/DiffuseChat)
+(GUI + CLI, one app for every diffusion LM in the catalog):
+
+```bash
+git clone https://github.com/john-rocky/coreai-kit
+open coreai-kit/Examples/DiffuseChat/DiffuseChat.xcodeproj
+# → Run, then pick "LLaDA-8B (diffusion)" in the model picker
+
+# agents / headless (macOS):
+cd coreai-kit/Examples/DiffuseChat
+swift run diffuse-cli --model llada-8b --prompt "What is the capital of France?"
+```
+
+💻 **Build with it** — complete; the glue is kit API, copy-paste runs:
+
+```swift
+import CoreAIKit
+
+let dlm = try await KitDiffusionLM(catalog: "llada-8b")
+let reply = try await dlm.reply(to: prompt)
+// reply: the denoised answer. onStep streamed the live canvas per forward
+// (still-masked positions as ░) — parallel fill-in, not left-to-right
+```
+
+The take-home is [`Examples/DiffuseChat/Sources/QuickStart.swift`](https://github.com/john-rocky/coreai-kit/blob/main/Examples/DiffuseChat/Sources/QuickStart.swift)
+— this exact code as one typed function, no UI; the CLI is an argument shell over it, and
+the GUI renders the same live canvas.
+The canvas is fixed (S=256 ≈ 210 generated tokens) and the whole history must fit — no
+KV cache. `reply(messages:)` takes role/content turns and drops the oldest first.
+Pass `onStep: nil` if you only want the final text.
+
+**Integration checklist**
+
+- SPM: `https://github.com/john-rocky/coreai-kit` → product **CoreAIKit**
+- Info.plist: none needed
+- Entitlements: none needed
+- First run downloads the model — 5.3 GB (Mac) — then it loads from the
+  local cache (Application Support; progress via the `downloadProgress` callback)
+- Measure in Release — Debug is ~3× slower on per-token host work
 <!-- gen-cards:use-it end -->
 
 ## What it looks like