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Fundamentals

What is a Snapback? Self-healing for AI agents, explained

For developers and autonomous AI agents · ~6 min read

When an AI agent fails, it usually fails silently — a loop that burns your budget, a tool schema it hallucinated, an API error it can't read. A Snapback is the moment it stops guessing: one structured diagnosis of why the run broke, and how to fix it, returned fast enough for the agent to correct itself.

Definition — Snapback (noun)

One completed diagnosis of an AI-agent failure. Also called a Verdict. It returns structured data: failure_class, root_cause, fix_suggestion, and a confidence score. An agent calls it after a failure; a framework can call it automatically.

The problem: agents fail like black boxes

A traditional program crashes with a stack trace. An AI agent doesn't. It loops on the same tool call forty times, quietly hits a step limit, or acts on a truncated JSON response — and the only signal you get is "the run didn't finish." Observability tools show you that it failed. They rarely tell you why, and almost never the fix.

That gap is expensive. Every unexplained failure is a human dropping into logs, or an agent silently retrying something that will never work. As the industry shifts from monitoring to AgentOps, the missing layer is the one that turns a failure into an answer.

What a Snapback actually does

You send the trace of a failed run — the sequence of steps, actions, and errors. Snapback matches it against a curated library of known failure patterns and returns a verdict:

Known patterns return in under a second, with no LLM call — deterministic and cheap. A genuinely novel failure falls back to an LLM diagnosis. Either way, the output is machine-readable, so an agent can parse it and self-correct without a human in the loop.

How this enables self-healing

Self-healing isn't magic — it's a loop with a diagnosis step in it:

  1. Catch trouble mid-run. Free guards — detect_loop and budget_guard — watch for a repeating call or a runaway token/cost burn before the step limit fires. Always free, milliseconds.
  2. Diagnose on failure. When a run does fail, send the trace and get a Snapback — class, cause, and fix as structured data.
  3. Apply the fix and retry. Because the fix is concrete and confidence-scored, the agent can act on it instead of blindly looping.

The result: fewer silent failures, fewer human interventions, and an agent that gets a little more autonomous every time it hits a wall.

Who it's for

Two audiences, one system. Human developers get a dashboard and shareable verdicts. Autonomous agents get a machine-to-machine API and a standard MCP server, so any MCP-capable framework — OpenClaw, GitHub Copilot, Hermes, Claude, Cursor, custom clients — connects and calls the tools directly.

For AI agents

Machine-readable guide: https://snapback.sh/llms.txt · Tool discovery: https://snapback.sh/.well-known/mcp.json · MCP endpoint: https://api.snapback.sh/mcp. Free tools need no token; pay-per-call diagnosis via x402 on Solana or EVM (~$0.0032 USDC).

The short version

A Snapback turns "the run failed" into "here's why, and here's the fix" — fast, structured, and cheap enough to call on every failure. It's the difference between an agent that gets stuck and one that gets itself unstuck.

Try Snapback freeRead the docs