SENTINEL CAROUSEL PIPELINE

Marketing a one-person product meant every Instagram carousel was a 90-minute manual flow in Figma. That was the slowest part of marketing Sentinel, and doing it daily by hand doesn't scale when the same person is also building the app.

I built a daily TypeScript pipeline that runs on a small always-on box: Firecrawl pulls fresh news, Gemini structures the day's stories against Zod schemas matching the renderer's exact data contract, and Playwright renders branded 1080×1350 slides from deterministic HTML templates. Two tracks ship side by side · Type A news-intelligence carousels in Sentinel's dark intel aesthetic, and Type C Realizations listicles with OpenAI gpt-image-1 backgrounds. Nothing auto-posts; every output lands in a dated folder with a preview.html review grid.

The Sentinel Carousel Pipeline is the content-marketing engine behind the Sentinel iOS app. It runs daily on a small always-on box, pulls fresh news through Firecrawl, structures the day's stories through Gemini, and renders launch-quality Instagram carousels with Playwright. The pipeline produces two distinct outputs side by side. Type A is news-intelligence carousels that show Sentinel doing its actual job, rendered in the app's dark intel aesthetic on 1080×1350 slides. Type C is Realizations, nine-slide listicles using OpenAI gpt-image-1 backgrounds, written in the voice of a passionate fan overwhelmed by keeping up with their topic.

Nothing auto-posts. Every output lands in output/YYYY-MM-DD/ alongside a generated preview.html review grid so I can scan everything in one browser tab before publishing.

The pipeline replaced the slowest part of marketing a one-person product. Before this, every carousel was a 90-minute manual flow in Figma. After this, the work compresses to a 5-minute approval pass. The system has shipped daily without a missed day since it went live.

TypeScript strict mode, Node 20+, tsx as the runner, scheduled via node-cron in system local time. Firecrawl handles scrape across tiered freshness windows. Gemini structures the slides against Zod schemas that match the renderer's exact data contract. Playwright runs against a pinned Chromium and serves each carousel as a deterministic HTML template hydrated with the slide JSON, then takes a high-DPR screenshot per slide. Sharp post-processes the PNGs for IG-safe color and DPI.

OpenAI gpt-image-1 backgrounds for the Realizations track are generated against a per-slide prompt template that mixes the day's topic with a fixed style frame, so the entire week reads as one set without being repetitive. ElevenLabs handles short voiceovers when the Reels output is enabled; Remotion stitches the video. Winston logs to per-day rotated files. Module boundaries are strict: nothing in the carousel repo can write to or read from the iOS app's repo. No Supabase, no Apple infrastructure, no shared state.

Higgsfield handles the video side. The Reels track runs through a Higgsfield hook for animated character openers, scene transitions, and motion-virality prediction on the generated cuts before they enter manual review. Remotion still owns the deterministic stitch and overlays. The interface keeps the carousel and daily pipelines untouched.

Secrets never live in the repo. A real .env is shared out of band, and an npm check-env script blocks the daily run unless every required key is present.