mold

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iPhone App ​

Mold for iPhone is a first-class remote studio for a Mold server. The phone does not run AI models itself: generation, model storage, downloads, queueing, and gallery files stay on one or more remote Mold hosts while the app provides an iPhone-native control surface.

Mold requires iOS 17 or later. The current build is distributed to invited internal and external TestFlight groups; there is not yet a public App Store listing.

Connect a host ​

Start a reachable server on the GPU machine. Use an API key whenever the server is reachable beyond localhost:

bash
MOLD_API_KEY='choose-a-long-secret' mold serve --bind 0.0.0.0 --port 7680

Open Machines on the iPhone and use one of these paths:

  • Recommended: open Settings → Mobile pairing in Mold desktop or web, confirm the LAN, MagicDNS, or HTTPS address the phone can reach, tap Pair an iPhone, then tap Scan pairing code on iPhone. The code is single-use, expires after two minutes, and contains no API key; the redeemed key goes directly into the iOS Keychain.
  • Tap Discover nearby to browse _mold._tcp services on the current LAN. Allow Local Network access when iOS asks.
  • Enter an IP address such as 192.168.1.10. Mold adds http:// and port 7680 when they are omitted.
  • Enter a DNS hostname, HTTPS URL, or Tailscale MagicDNS name.

For manual entry, paste the same API key, then tap Test and save. Saved host metadata remains in the app's local storage, while the API key is kept separately in the iOS Keychain.

Tailscale ​

Tailscale is the simplest way to reach a private GPU host away from its LAN:

  1. Join the iPhone and GPU host to the same tailnet.
  2. Keep mold serve listening on an address the Tailscale interface can reach.
  3. Add the host by its MagicDNS name, for example plato or plato.example-tailnet.ts.net. Mold supplies port 7680 for a bare name.
  4. Include https:// and an explicit port only when your own reverse proxy provides TLS.

Bonjour discovery is LAN-local; Tailscale hosts are normally added by name. Mold uses the installed Tailscale network and does not manage tailnet login, ACLs, DNS, or certificates.

Create ​

Choose a host and one of its installed generation models. The form adapts to the selected model family and uses the same request contract and model defaults as desktop. The primary controls stay on the main screen; deeper options open in a full-screen Advanced sheet, and prompt style presets compose at submit without rewriting your prompt text. A ↺ Reset beside the Advanced trigger restores every generation setting to the selected model's defaults, keeping your prompt, model choice, and any prepared batch.

The mobile composer includes:

  • a directly editable Batch count, Batch 1 quick prompt expansion with undo, compact/paged Batch N prepared-variation review, and remote prompt history;
  • local templates that can be saved, searched, sorted, renamed, loaded, and deleted;
  • batch generation as independent queued jobs, each with its own progress and Cancel action;
  • source images and fit policies, Qwen edit target/reference images, masks, ControlNet, LoRA stacks and trigger words;
  • scheduler, CFG++, steps, guidance, output format, and post-generation upscaling where the selected family supports them;
  • validated video frames/FPS, audio, camera motion, source media, keyframes, retake, Continue a video (extending an existing clip on models that advertise it, including capable Wan checkpoints — resolution and fps stay locked to the source clip), LTX-2 pipeline/spatial/temporal controls, and optional STG, CFG-rescale, modality-scale, and guidance-skip overrides;
  • an Output field (One shot | Sequence) above the model field that turns the composer into a multi-clip sequence; and
  • a host-aware memory estimate before submission.

For video-only LTX-2 community checkpoints, Generate audio is disabled with an explanation when the connected server reports that the installed files lack an audio VAE or vocoder. Source-image video generation remains available. Empty guidance-override fields preserve the pipeline defaults. Invalid block lists or numeric ranges stay in the Advanced sheet with inline feedback and cannot queue a request; Reset advanced, templates, and Library reuse share the same saved override state as desktop.

Choose resolution through orientation, proportionally drawn aspect-ratio tiles, a resolution tier, or explicit custom dimensions. Seed has separate Random and Fixed modes, including one-tap reuse of the last generated seed.

When several jobs are submitted, the Queue section keeps them visible while you continue composing. Mold limits simultaneous streams so generation does not starve gallery or download requests.

For model families that stream live latent previews (FLUX.1, Flux.2, Z-Image, and Wan 2.1/2.2), the active print develops right on the Create screen: the preview sharpens as denoising progresses under a thinning film-grain wash, in a bed matching the print's aspect ratio. Hosts without previews keep the plain status line.

Batch is also the expansion count. Batch 1 freezes the selected host through the next Develop while keeping quick undo. Batch 2 or greater first requests exactly N distinct non-empty prompts from that host and opens an inline workspace where you can edit, intentionally remove, regenerate, refresh, or discard them before anything is queued. Above eight, the workspace shows a compact first-eight summary and bounded pages on demand. Queue acceptance immediately restores the composer so another batch can be prepared while the earlier one runs. A single reviewed set has a 10,000-variation memory-safety ceiling, but you can keep queueing additional sets. Reducing two prompts to one requires confirmation. Changes to the source prompt, model, family, Batch count, host endpoint, Keychain key, or server identity preserve the reviewed work with a specific stale reason and block Develop until you choose Refresh or Discard.

The same frozen host is used for expansion-model pulls, source preprocessing, and every sibling. Missing-model recovery stays inline with Connecting, Starting, Queued, percentage/bytes/files/ETA Pulling, Ready, and failure or cancellation retry states. The original inputs and route remain one immutable recovery record, and an attempt lease prevents a newer Models credential from redirecting the pull. Compatible Models work already in Starting is joined; every terminal, stale, superseded, or aborted attempt releases the lease before Retry reacquires the same frozen route. Editing/removing reviewed work cancels a pending replacement. Siblings remain independently cancellable and keep deterministic seeds, the source prompt, and durable batch position through long-video chains. A partial result names each failed variation and reviewed prompt, plus any separate unconfirmed-cancellation caveat, while keeping successful prints. Library shows Batch N of M and the source prompt when that provenance is present; prints from older servers remain unchanged.

When iOS suspends the app, interrupted generation streams carry a structured recovery marker rather than relying on localized WebKit error text. On resume, Mold checks the frozen host and bounds any pre-ID queue or durable-chain join to the original submission window, so a later fixed-seed duplicate is never cancelled or reported as the interrupted print.

Library ​

Library merges prints from every saved host, newest first. Unavailable hosts are reported without hiding media from hosts that did respond.

Press and hold an image to open the native iOS image menu for Share, Save to Photos, Copy, Copy Subject, and Look Up. Tap Select to select multiple prints; the action bar can select all loaded prints, clear the selection, or delete the selection. Deletion removes every matching copy from each reachable saved host, including legacy copies whose auto-save filename differs. If a host cannot complete the delete, its copy remains visible and Library reports the partial cleanup.

Tap a tile to open the full-screen viewer:

  • images are shown uncropped;
  • generated images open this same viewer when tapped;
  • videos stream from their owning host with native playback and seeking;
  • use Save video to add the original MP4 to Photos;
  • swipe left or right to move through the loaded prints; and
  • use Copy image or Save photo instead of the system long-press menu;
  • use Use as prompt to restore recorded generation settings, or Use as source to attach a still to the next compatible generation.

New installs also save completed stills to the iPhone Photos library automatically. Disable Settings → Photos → Save to Photos automatically if you want outputs to remain only in Mold Library. Post-generation upscaling saves both the original and upscaled image; videos remain on their Mold host.

Prints added since the prior Library visit carry a New badge. Images enlarged by post-generation or standalone upscaling carry an Upscaled badge on both iPhone and desktop.

Reusing settings switches to the print's host and restores the model when it is installed there. If the original model is unavailable, Mold clearly identifies the compatible fallback and removes non-portable adapter/component choices. On a print a sequence produced, Use as prompt instead reloads its recorded clips onto the Create clip rail as a new sequence — saying how many it restored and naming anything a print does not record — and substitutes a sequence-capable model when needed. Re-entering the original durable job (Edit sequence) is a desktop and web action.

Authenticated hosts issue a short-lived read-only media ticket for the selected file. The app never puts a long-lived API key in a video URL or buffers an entire video into phone memory.

Models ​

Models combines installed models with live Hugging Face and Civitai results. You can search, filter All/Images/Video, filter by source, family, or model kind (Models, LoRAs, CLIP, text encoders, VAEs, tokenizers, ControlNet), sort by downloads, rating, or recency, inspect download contents and installed components, and include NSFW entries explicitly. Every card identifies the model kind; mature results carry an 18+ NSFW badge. The detail sheet repeats those classifications, uses a kind-specific weights label, and shows available description, source, license, tags, format, and popularity metadata. When a manifest model has multiple quantizations, its detail sheet shows variant chips with checkpoint sizes; the selected chip is the exact model the Pull action downloads.

The family list comes from the browsed host. If that host is unreachable when Models opens — or its saved key has not been read from the Keychain yet — the list falls back to every family Mold has seen this session, from both catalog results and the installed models on your hosts. That set only grows, so choosing a family never shrinks the list to that one choice, and it can offer families that are not on the current page. The real list, and any search that failed, reload as soon as the host answers.

The host selector controls where Models browses. Pulling a model can target a different ready host without changing the host selected in Create. With more than one target available, Mold opens a host picker.

Pull buttons reflect the server state immediately:

  • Connecting... while the download event stream opens
  • Starting... while the request is accepted
  • Queued while waiting for a download slot
  • Pulling N% during transfer

Active downloads stay pinned above results and can be cancelled. Installed model details offer Load on GPU, Unload from GPU, and a guarded Remove from host action.

Host details ​

Tap a saved host to inspect its current state. The detail screen shows:

  • GPU/VRAM, CPU, and RAM telemetry;
  • every GPU's utilization, VRAM, lifecycle state, and enable/disable control;
  • free and used storage for the models filesystem;
  • queued/running generation work, with a confirmed Cancel action for work that has not started yet, and loaded models;
  • queued/active model downloads with progress; and
  • the models installed on that host.

From the same screen you can rename or retry the host, select it for Create, unload a model, open it in Models, or forget it. Forgetting a host also deletes its API key from the iOS Keychain. Queue cancellation uses that host's Keychain-authenticated route and refreshes the list after the server confirms it; running GPU work cannot be safely preempted and has no Cancel action.

Settings and themes ​

Open Settings from the sliders button in the header. Mobile settings currently cover:

  • Color family: the Mold Studio theme families, Mold or Safelight
  • Appearance: System, Dark, or Light
  • Photos: automatically save newly generated stills to the iPhone photo library (on by default)
  • Remote hosts: saved-host count and a shortcut to manage them
  • GPUs: enable or disable each GPU on the selected host; a busy GPU finishes its current stage before disabling
  • About: app version, remote-only processing, TestFlight updates, and equal project-owner credit for core contributors James Brink and Jeffrey Dilley, plus an external link to the Mold privacy policy

Fresh installs start with the Safelight color family, System appearance, and Photos auto-save enabled. Existing users keep any valid saved choices, with auto-save enabled when upgrading from a settings record that predates the option.

The appearance choice updates both the WebView and native iOS system chrome so status-bar content remains readable. Themes change the app chrome but never recolor generated photos or videos.

The app intentionally prevents WebKit input-focus and double-tap page magnification and suppresses rubber-band scrolling. The Library's horizontal swipe navigation remains enabled. iOS system-level accessibility Zoom is separate from WebView page zoom.

Updates and current boundaries ​

Internal TestFlight builds are created automatically after mobile-relevant changes pass the iOS workflow on main. The pipeline validates the bundled mobile index.html, Mold icon catalog, native archive, App Store Connect processing, and internal tester access before it is considered complete.

The iPhone app focuses on remote Create, Library, Models, Machines, and appearance settings. Multi-clip video is a setting inside Create, not a separate screen: set Output to Sequence and the composer becomes a clip list, narrowed to compatible installed video models and sharing one set of size, FPS, steps, guidance, and seed fields with One shot. Start with two clips, describe each shot, choose the duration, and generate while Mold keeps progress and cancellation attached to the exact host — sequences share one queue list with single prints. Between clips, a seam control opens a sheet naming the transition in words (Smooth, Cut, Fade) with the fade-length stepper. New clips take their frame count from the selected model's own advertised default. An interrupted sequence can reconnect after relaunch without storing the host API key outside the Keychain; if the saved server identity cannot be verified, Mold discards the recovery record instead of attaching to an unproven machine. LTX-Video joins independent clips without a motion tail and labels its seams Join, while LTX-2 offers only durations longer than its continuation overlap. Wan checkpoints sequence too: clip durations snap to Wan's 4n+1 frame grid, image-conditioned checkpoints (A14B I2V, TI2V-5B) continue motion across the seam from a single carried frame, and text-to-video Wan checkpoints join independent clips like LTX-Video. Use desktop or the CLI for a local engine, in-place sequence editing and the Sequences history tab, the TOML chain editor and full jobs-administration workspace, RunPod provisioning, engine configuration, and desktop Stable/Nightly self-update controls.

For server networking and deployment options, continue with Remote Workflows. For supported model-family controls, see Feature Support.

Troubleshooting ​

Discovery finds nothing ​

  • Confirm Local Network access is enabled for Mold in iOS Settings.
  • Confirm the phone and host are on the same LAN; Bonjour does not browse a remote tailnet.
  • Confirm the server was not started with --no-mdns or MOLD_MDNS=0.
  • Add the IP address or Tailscale MagicDNS name manually.

The host test fails ​

  • Open http://host:7680/health from another device on the same network.
  • Confirm the server listens on 0.0.0.0, not only 127.0.0.1.
  • Check the firewall, Tailscale ACL, port, scheme, and API key.

A video will not play ​

Update the remote Mold host. Current authenticated video playback needs the short-lived gallery media-ticket endpoint so iOS can make native Range requests without exposing the API key.