feat(genmedia): provider-agnostic generative media layer

[ralyodio]

Why

Seven repos in the portfolio — viral-video, makedemo, amazon-affiliate, reeleel, brisk.news, bl0ggers, intr0s — have each independently rebuilt the same pipeline: script → images → TTS → ffmpeg mux → MP4. amazon-affiliate alone carries 331 ffmpeg references and 77 ElevenLabs references. This repo already owns 491 ffmpeg references and no generation at all, which makes it the natural place for the shared layer.

What

One interface for generating images, video, speech and music, sitting next to the existing ffmpeg presets. Generated assets come back as ordinary files, so the current pipeline picks them up with no glue code.

No new runtime dependencies. Every provider is a plain fetch against a documented REST endpoint, using the global fetch in Node 20+.

Provider	Capabilities	Credentials
google	image, video, speech, music	GOOGLE_API_KEY (Lyria also needs GOOGLE_CLOUD_PROJECT + GOOGLE_ACCESS_TOKEN)
openai	image, speech	OPENAI_API_KEY
elevenlabs	speech	ELEVENLABS_API_KEY

Notable behaviour

• Provider resolution picks the first preferred provider for a capability that actually has credentials configured. Overridable per call via provider, or globally via GENMEDIA_PROVIDER. Speech deliberately prefers ElevenLabs so shipped products don't silently change voice.
• Veo returns synchronized audio, so the separate voiceover and mux stages can be dropped entirely from a short-video pipeline. Long-running operations are polled to completion with progress callbacks.
• Google speech returns headerless PCM, which is wrapped in a WAV container automatically so ffmpeg needs no out-of-band format hints.
• generateBatch bounds concurrency, preserves input order, and captures per-item errors rather than failing the run — an unbounded Promise.all over a storyboard is the fastest route to 429s.
• Retries use exponential backoff with Retry-After support on 429/5xx; client errors such as a rejected prompt fail immediately rather than burning the retry budget.
• Custom providers can be registered with registerProvider().

Testing

53 new tests, all green. Every provider call is exercised through an injected fetchImpl, so the suite runs offline and without credentials.

npm run test:genmedia   # 53 passing

The other 50 failures in the full suite are pre-existing and unrelated — this box has no ffmpeg installed, and the count is identical with and without this branch (47 pre-existing passing either way).

examples/genmedia.js is a runnable walkthrough; it was syntax-checked but deliberately not executed, since it would make billable API calls.

🤖 Generated with Claude Code

[github-actions]

ThreatCrush Security Scan

1 finding(s)

LOW: 1

Severity	Rule	Location
LOW	secret-generic-credential	test/genmedia.test.js:611

Snippets are redacted; ThreatCrush never prints matched credential material.