Reely turns an iOS feature into a clean, auto-zoomed, captioned sizzle reel — from inside your own AI coding agent. You stay in Claude Code (or any MCP host); it authors a faithful mock of your feature and calls Reely’s local run_reel tool, which builds, drives the Simulator, records, composites the look, and opens the finished reel in the Reely viewer.
“Make a sizzle reel of the onboarding flow.”
Authors a mock + FeatureAdapter + FlowSpec (your key, no LLM cost to us).
build → Simulator → drive → record → composite → opens the viewer.
The authoring half is the LLM’s job. The rendering half — run_reel — is Reely’s deterministic engine, exposed as a local stdio MCP tool and shared with the reely run CLI.
Reely is macOS-only and uses your local Xcode + iOS Simulators. Setup is three parts: install the tooling once per machine, wire Reely into a repo once, then generate reels by asking your agent.
xcodegen installed (Apple Silicon recommended).claude) installed and authenticated — logged in, or ANTHROPIC_API_KEY set.ffmpeg / ffprobe on PATH (used for verification only).Build a stable reely binary (.mcp.json points at it — don’t use swift run, its path is ephemeral), then build and launch the viewer once so macOS associates .reelyproj with it.
cd /path/to/Reely
swift build -c release # → .build/release/reely
cd Editor && xcodegen generate
xcodebuild -project ReelyEditor.xcodeproj -scheme ReelyEditor \
-destination 'platform=macOS' -derivedDataPath build
open "build/Build/Products/Debug/Reely Editor.app" # registers it, then quitPoint install at the iOS project you want reels for:
/path/to/Reely/.build/release/reely mcp install --repo /path/to/YourProjectThis writes, non-destructively (existing entries are preserved):
| File (in your repo) | What it does |
|---|---|
.mcp.json | Registers the reely stdio MCP server (absolute binary path + a 15-min tool timeout). |
.claude/settings.json | Pre-approves mcp__reely__run_reel so the call never blocks on a permission prompt. |
.claude/skills/reely-sizzle-reel/ | Copies the authoring skill into the repo, and materializes .reely/scaffold/. |
Re-run install any time you rebuild the binary at a new path, or to refresh the skill.
Run claude in your repo, approve the project’s MCP server when prompted, and confirm with /mcp — you should see reely connected. For a no-authoring smoke test, install into the Reely repo itself and run the tool against the bundled harness:
Call run_reel with harness Harness/ReelyHarness.xcodeproj,
scheme ReelyHarness, spec Fixtures/create-project.flowspec.json.If the viewer pops up on a finished reel, the whole pipeline is healthy.
run_reel toolEverything below is one tool. Your agent calls it; you steer it with a plain-English prompt. Paths are relative to the repo root. It is single-flight — it shares one Simulator + scratch dir, so a second concurrent call is rejected until the first finishes.
| Argument | Required | Default | Notes |
|---|---|---|---|
harness | required | — | Path to the recording target .xcodeproj / .xcworkspace (relative to the repo). |
scheme | required | — | Scheme of the recording target. |
spec | required | — | Path to the Flow Spec JSON — the ordered steps to drive. |
device | — | iPhone 16 Pro | Simulator device name. Must exist in xcrun simctl list devices. |
output | — | out/reel.mp4 | Output video. A sibling .reelyproj bundle is always written next to it. |
effects | — | true | Apply the sizzle effects: padded canvas, auto-zoom, dead-air cuts. |
themeFromApp | — | false | Colour the background, captions and contact shadow from the app brand. |
brandBundle | — | built harness | Path to the real product .app / .xcassets / app icon to theme from. |
captionFont | — | system | Caption typeface: a curated preset, system, app, or any PostScript name. |
Captions have no argument: the agent writes caption copy onto FlowSpec steps and they auto-enable from the spec content.
Each case is a real prompt you’d type to the agent, and the reel it produces. Together they cover every parameter — go from all-defaults to a fully branded, captioned App Store preview by changing what you ask for.
/reely-sizzle-reel Make a sizzle reel of the onboarding flow.
The baseline. The skill authors a brand-faithful mock + FeatureAdapter + FlowSpec, then calls run_reel with only the three required paths. Device, output and effects all take their defaults.
/reely-sizzle-reel Make a reel of onboarding with captions that explain each step.
Captions are not a tool parameter — the agent is the copywriter. It writes a caption field onto the hero beats of the FlowSpec, and captions auto-enable when the spec carries any copy. The run_reel call is unchanged.
/reely-sizzle-reel Make the reel and brand it with our app’s colors and font.
Theme-from-App is opt-in. With themeFromApp: true the compositor pulls the background, caption palette and contact shadow from the brand surface — and swaps captions into the app’s own embedded font.
/reely-sizzle-reel Brand the reel from our shipping MyApp.app.
By default Theme-from-App reads the built harness app. Point brandBundle at the real product to extract the true palette + icon — it accepts a .app, an .xcassets, or an app-icon image.
/reely-sizzle-reel Use Avenir Next for the captions.
captionFont overrides the caption face. Choose one of ten preinstalled iOS presets (helvetica-neue, avenir-next, futura, gill-sans, optima, georgia, palatino, baskerville, american-typewriter, menlo), or system, app (force the extracted brand face), or any PostScript name.
/reely-sizzle-reel Record the reel on an iPhone SE.
device selects the Simulator. It must be a device name present in xcrun simctl list devices; output is device-native portrait.
/reely-sizzle-reel Save the reel to marketing/launch.mp4.
output sets the mp4 path (relative to the repo). A reopenable .reelyproj bundle — raw.mov + timeline.json + effects.json — is always written next to it for the viewer.
/reely-sizzle-reel Just give me the raw recording — no zoom or background.
effects: false writes a plain trim: the synced, dead-air-free recording with no padded canvas, auto-zoom or cuts. Useful when you want to grade or composite the footage yourself.
/reely-sizzle-reel Make a fully-branded, captioned App Store preview and save it to out/appstore.mp4.
The combined case: the skill bakes caption copy into the spec, themes from the app brand with captions in the brand face, and writes to a named path — one call, every lever.
Everything run_reel does is also a plain command — useful for CI or headless use. The same engine backs both.
reely run \
--harness Harness/ReelyHarness.xcodeproj --scheme ReelyHarness \
--spec Fixtures/create-project.flowspec.json --device "iPhone 16 Pro" \
--output out/reel.mp4 --project out/reel.reelyproj
open out/reel.reelyproj # open it in the viewer
# Re-author the look on an existing recording, no re-record:
reely effects out/reel.mp4 --timeline out/reel.timeline.json --output reel.mp4The same run_reel surface is what a hosted cloud-Mac renderer would expose later — moving from local to cloud is swapping the MCP endpoint, not a rewrite.