Today, we're proud to launch Subtext and usher in the era of Agentic Session Review (ASR).
The first ten years of Fullstory were really about helping human teams find, forensic (I verbed it), and fix bad digital experiences.
Fullstory led the way with a radical approach to safely capture and structure behavioral data, and yes, the best damned session replay in the world. It is still the best by a country mile (source: biased founder). Session Replay, when we launched it way back when, was like magic — an easy and powerful way for our customers to truly understand and empathize with their visitors. That remains true today, and it isn't going anywhere. Humans still need to watch things.
But something else is happening now. It's not just humans who need to watch things anymore.
Within the next 6 months, AI agents will watch more sessions than every human combined.
They won't scrub through a playback moment-to-moment the same way a human would. They'll do what we are calling Agentic Session Review, navigating structured, queryable behavioral truth: what happened, in what order, on what element, with what state around it.
This behavioral truth is exactly what Fullstory has been capturing under the hood for a decade and refined across billions of real sessions, not stitched together from an open-source recorder last quarter. We built it so humans could watch a replay and perform deep analytics. It turns out it's even more valuable as raw material for a model that can reason over structure directly and never gets bored or distracted after watching the 100th replay.
That's the bet behind Subtext: the data we've always captured is better appreciated by AI than it ever was by humans.
Subtext is a behavioral capture and delivery layer built for agents as the primary user persona. It lets AI agents you already use (Claude Code, Cursor, Codex, Devin, or your own harness) open and investigate a session directly, with tools designed for progressive disclosure: reading console errors, network calls, DOM state, and heuristic signals galore (flex: remember Fullstory created Rage Clicks). The agent pulls in only what the question needs, one layer at a time, to guide attention.
To lead the Agentic Session Review opportunity we created a separate internal team with a simple, slightly uncomfortable charter: design a product as if AI is the primary user, not humans. That clarified a lot. Simple CLI install. Headless. Tools shaped around token efficiency instead of visual polish. Attention management. Make privacy controls increasingly automated.
Also, importantly, we rethought pricing to make it super cheap to capture everything, because sampling makes no sense when your user is a model that can process the full picture at scale.
If you're building something new, or your team is already leaning into agentic workflows, please give Subtext a try: npx @subtextdev/subtext-wizard or head on over to subtext.fullstory.com. It's free to start. Tell us where it breaks or where we can improve it. We've got an exciting backlog of things and will be shipping updates fast. Stay tuned!