Model-Grounded Text-to-Video Workflow
Overview
Treat model choice as an API-schema decision, not a marketing label. Runway request bodies are discriminated by model; valid ratios, durations, prompt limits, optional controls, price, and even required fields can differ between models.
Prerequisites
- A product requirement covering quality, latency, duration, ratio, and budget
- Current Runway models, API reference, and pricing pages
- Durable task tracking and owned output storage
Instructions
Step 1: Define the output contract
Record modality, intended use, dimensions, duration, audio need, quality threshold, deadline, moderation policy, and maximum credits. Separate hard constraints from preferences.
Step 2: Choose direct model or router
Use a direct model when reproducibility requires a reviewed identifier. Use a saved Model Router when policy should optimize cost, latency, or quality within approved allow and deny lists; use its dry run before billable work.
Step 3: Read the exact variant
Inspect the current text_to_video schema for the chosen model. For example, gen4.5 currently supports text input, but this skill does not transplant its ratio or duration fields to another model.
Step 4: Freeze and submit
Persist the model or router config, normalized request, documentation fingerprint, and approval before create. Store the returned task ID immediately.
Step 5: Observe without duplication
Use the SDK wait helper or bounded polling. Treat THROTTLED as queued and distinguish queue time from execution time. Recover from client interruption by retrieving the saved task.
Step 6: Validate and preserve
On success, download output, verify media type, duration, dimensions, and checksum, then run the product quality review. On failure, apply the HTTP or task-failure policy rather than silently changing models.
Authentication
All model, router, task, and usage calls use the server-side Runway API secret. Direct HTTP also sends the reviewed X-Runway-Version; temporary output URLs remain confidential until copied to controlled storage.
Use Read and Grep to inspect application configuration, provider documentation, lockfiles, fixtures, schemas, tests, and redacted operational evidence before proposing a change. Use Write or Edit only for an approved implementation, configuration, test, runbook, or redacted receipt. Do not create, cancel, delete, retry, deploy, rotate, revoke, publish, or otherwise mutate production Runway resources without explicit operator approval.