Replicate universal gateway — run any Replicate-hosted model (image, video, audio, 3D, or text) by typing its owner/name slug into one node, with one API token. Capabilities: text-to-image, image editing/upscaling, text/image-to-video, music/TTS/transcription, image/text-to-3D, and open LLM text — all via a single passthrough node that resolves the model version, creates an async prediction, and polls to completion. Activate when the user configures the `replicate-universal` node (display name "Replicate") or asks about Replicate in Nebula. Sourced from the official Replicate HTTP API reference (replicate.com/docs/reference/http) and the Nebula audit guide docs/api-guides/replicate.md on 2026-06-04 — node id, the single model_id param, async-poll execution, and output-type inference are cross-checked against backend/data/node_definitions.json and backend/handlers/replicate_universal.py.
Replicate universal gateway — run any Replicate-hosted model (image, video, audio, 3D, or text) by typing its owner/name slug into one node, with one API token. Capabilities: text-to-image, image editing/upscaling, text/image-to-video, music/TTS/transcription, image/text-to-3D, and open LLM text — all via a single passthrough node that resolves the model version, creates an async prediction, and polls to completion. Activate when the user configures the `replicate-universal` node (display name "Replicate") or asks about Replicate in Nebula. Sourced from the official Replicate HTTP API reference (replicate.com/docs/reference/http) and the Nebula audit guide docs/api-guides/replicate.md on 2026-06-04 — node id, the single model_id param, async-poll execution, and output-type inference are cross-checked against backend/data/node_definitions.json and backend/handlers/replicate_universal.py.
Replicate Skill
When to use
User configures the replicate-universal node (shown as "Replicate" on the canvas, under the universal category).
User wants to run a specific Replicate model by slug (e.g. black-forest-labs/flux-schnell, stability-ai/sdxl) for an image, video, audio, 3D, or text result.
User asks "how do I use Replicate in Nebula", how to wire a model's inputs, or which model slug to pick for a media type.
User asks why a Replicate model input isn't showing as a port (answer: there are no fixed ports — see the contract below).
User asks about Replicate auth/setup (REPLICATE_API_TOKEN) or about features Replicate has that Nebula doesn't expose (streaming, fine-tuning, deployments, model search).
This is the ONLY Replicate node. There is no per-model node, no image/video/audio split — every Replicate run goes through replicate-universal.
Universal rules
Auth — bearer token from one env var. The handler reads REPLICATE_API_TOKEN and refuses to run without it (raise ValueError("REPLICATE_API_TOKEN is required")). Every HTTP call sends Authorization: Bearer <REPLICATE_API_TOKEN>. Get a token at https://replicate.com/account/api-tokens (format r8_...), set REPLICATE_API_TOKEN=r8_... in the backend's .env / shell env, then restart the backend so it loads the variable.
Base URL.https://api.replicate.com/v1. Three routes are used: GET /v1/models/{owner}/{name} (resolve the version), POST /v1/predictions (create), GET /v1/predictions/{id} (poll).
Execution pattern — async-poll for media, SSE for text (confirmed from the handler). No sync Prefer: wait, no webhooks. Text/LLM models that return urls.stream now stream token deltas live (auto-detected — see gotcha 6); everything else async-polls. The poll flow is:
Split model_id on / into owner and name.
GET /v1/models/{owner}/{name} → read latest_version.id. This becomes the version hash the create call requires. (If a private _version_id param is already set on the node, that is used instead and the lookup is skipped.)
POST /v1/predictions with body {"version": <id>, "input": <merged inputs>}.
Poll GET /v1/predictions/{id} every 2 s, up to 300 times (~600 s / 10 min ceiling). Statuses starting/processing keep polling; terminal success is succeeded, terminal failure is failed or canceled.
Read output from the succeeded prediction and infer its port type (rules below).
Status / error codes. Submit must return 200 or 201 (else RuntimeError("Async submit failed (<code>): <body>")). Each poll must return 200 (else RuntimeError("Poll request failed ...")). On a failed/canceled prediction the handler raises Async job failed: <prediction.error>. On hitting the 300-poll cap it raises Async job timed out after 300 polls (600s). A missing output on success raises RuntimeError("Replicate returned no output"). The version lookup raises if the model 404s or has no version. Common HTTP causes: 401 bad/missing token, 402 insufficient credit / spend limit, 404 wrong slug, 422 invalid input for that model's schema, 429 rate-limited.
Input-URI rules. Nebula does not use Replicate's Files API. File-type model inputs (an image, audio, video, mask field, etc.) must be passed as public HTTPS URLs or data URLs — the handler forwards input values verbatim into the prediction's input object with no upload step. When chaining from an upstream Nebula node, the upstream output is a served URL that you map straight into the downstream model's file-input field by its exact name (e.g. an Image output → a model's image or input_image field).
Key gotchas.
No fixed ports + no baked schema.inputPorts and outputPorts are both []. The node has no idea what fields the chosen model wants. You must know the model's input field names (from its replicate.com page → Inputs, or GET /v1/models/{owner}/{name}) and name your connected ports / extra params to match exactly. Misspelled or missing required fields surface as a 422/failed from Replicate, not a Nebula validation error.
model_id must contain a /.owner/name only. A bare name like sdxl raises ValueError("Model ID is required (format: owner/name ...)"). Do not append a :version — versioning is resolved automatically to the model's latest version.
Latest version only. The handler always resolves latest_version; there's no version picker. If you need a pinned older version, that's not exposed (the private _version_id is an implementation detail, not a user control).
Empty params are dropped. Params that are None or "" are not sent. To pass a value you must give it a non-empty value.
Progress is fake. The progress bar is just poll_number / 300, not real model progress — Replicate's prediction progress/logs are not surfaced. Don't promise a live percentage.
Token streaming (text/LLM), auto-detected (2026-06-08). When the created prediction returns urls.stream, the handler consumes the SSE stream and emits live token deltas (rendered as streamingText) — no param, no node change. Replicate's output SSE data is RAW TEXT (not JSON, unlike the chat providers). Non-text models (image/video/audio/mesh) have no token stream and poll as before. The 30 s idle-reconnect (Last-Event-ID) is not implemented, so a very long idle gap could truncate.
Pick the right node
Node (in app)
Node ID
Endpoint(s)
Required param
How other inputs work
Replicate
replicate-universal
GET /v1/models/{owner}/{name} (version resolve) → POST /v1/predictions → GET /v1/predictions/{id} (poll)
None pre-defined. Every connected input port and every extra param (except the internal keys model_id, _version_id, _schema_fetched) is merged into the prediction's input object using the port/param name as the model input field.
One node covers all media types. The media type of the result is inferred from the output, not declared — see "Param reference" and the inference rules.
Recommended default model slugs (per media type)
The node can't list models, so seed sensible defaults and tell the user to confirm field names on the model page. These are stable, popular slugs as of 2026-06-04 — verify availability on replicate.com before quoting cost/behavior:
Format owner/name. Placeholder: owner/name (e.g. stability-ai/sdxl). Must contain a /. Do not include a :version.
There are no other declared params and no input ports. Everything else a model needs is supplied dynamically:
Connected input ports — created by you when wiring the graph; the port name must equal the model's input field name. The handler maps inputs[port_name].value → input[port_name] (skipping None values).
Extra params — any ad-hoc param you add to the node (e.g. prompt, width, seed, negative_prompt). The handler maps params[key] → input[key] for every key except the internal set {model_id, _version_id, _schema_fetched}, dropping None/"".
Internal-only keys (not user-facing controls): _version_id (a pinned version hash, normally unset so the latest is resolved) and _schema_fetched (a caching flag). Don't set these manually.
Output-type inference (from _infer_output_type in the handler) — the result's shape decides the port:
A model that returns a list of images only yields its first image downstream. If they need all of them, that's a current limitation.
A model that returns a dict (structured output) is flattened to a Text port (stringified) — not parsed into typed fields.
A file with an unusual extension (e.g. a .glb/.obj 3D mesh, or a query-string-laden signed URL) may be mislabeled as Image because only the listed extensions are special-cased. Chain it where the URL itself is what matters, or be aware the port type is a best-guess.
Recipes
All recipes use the real node id replicate-universal.
Text-to-image (single node). Drop a replicate-universal, set model_id = black-forest-labs/flux-schnell, add a prompt param ("a neon crab on a beach at dusk"). Run → the output URL ends in an image extension → an Image port you can preview or download.
Image-to-video chain (two Replicate nodes). Node A: model_id = a text-to-image model with a prompt → Image output. Node B: model_id = an image-to-video model; wire A's Image output into B's input_image (or image) field — match the model's real field name — and add motion params as needed. B's output URL ends in .mp4 → Video port. Nebula passes A's served image URL straight into B's input.
Transcribe then summarize (two Replicate nodes). Node A: model_id = a Whisper-family model, with an audio field set to a public URL/data URL → returns a plain string → Text port. Node B: model_id = an instruct LLM slug, with prompt set to "Summarize:\n" + the upstream text (mapped from A's Text output) → Text port. Two gateway nodes, no custom node code.
Handler:backend/handlers/replicate_universal.py (handle_replicate_universal). Version resolve helper _resolve_version; output typing _infer_output_type. Async polling runs through backend/execution/async_poll_runner.py (async_poll_execute / AsyncPollConfig) — submit accepts 200/201, polls require 200, 2 s interval, 300-poll cap, failure reads the prediction's error field.
Input ports: none declared. You add ports at graph-build time and name them to the model's input fields. Each connected port's value is forwarded into the prediction input under that exact name.
Output ports: none declared; a single port is produced at runtime, typed image / video / audio / text per the inference table. There is no task_id output port (unlike Meshy) — chaining is by the inferred media port only.
Chaining rules: map an upstream media output into the downstream model's file-input field by name (Image → image/input_image, Audio → audio, Text → prompt/system_prompt). Upstream outputs are served URLs that Replicate fetches directly — no re-upload.
How outputs render: Image/Video/Audio ports render in the canvas's standard media previews; Text ports show as text. Mislabeled ports (see inference caveats) still carry the raw URL/string.
Capability boundaries (what Replicate's API can do that Nebula does NOT expose)
Never promise these through the replicate-universal node — they're in the API but unwired (per the audit gap table in docs/api-guides/replicate.md):
No Files API upload (POST /v1/files). File inputs must be public URLs or data URLs the user supplies; Nebula won't host a local file for them.
No streaming (SSE via urls.stream). Token-by-token LLM/text output is not surfaced — results arrive whole at completion.
No synchronous mode (Prefer: wait header). Always polls at 2 s; fast models can't return faster via a held request.
No webhooks (webhook_events_filter). Completion is detected by polling only; no callbacks.
Cancellation IS wired (2026-06-05, best-effort): on node cancellation the shared async-poll runner POSTs /v1/predictions/{id}/cancel so the run stops upstream instead of running to the 10-min ceiling. (No Cancel-After runtime cap, though.)
No prediction history / listing (GET /v1/predictions).
No deployments (/v1/deployments…) — private/auto-scaling endpoints aren't reachable.
No trainings / fine-tuning (/v1/…/trainings, GET /v1/trainings/{id}).
No in-app model search / collections (QUERY /v1/models, GET /v1/models, /v1/collections, GET /v1/search). The user must already know the owner/name slug.
No version picker / examples / readme — only the model's latest version is used; no pinning to an older version, and no examples/readme surfaced.
No official-model convenience route (POST /v1/models/{owner}/{name}/predictions), no hardware list (GET /v1/hardware), no account info (GET /v1/account). Roughly ~20% of the Replicate API surface (create + poll + version-resolve) is wired — the full run-a-model happy path, none of the management/streaming/async-callback surface.
