Check what's asserted as real against reality — in both directions — before it ships.
Goal
The author's "plausible / absurd / novel" is the least reliable line in any artifact. Human priors fail both ways — they exclude the real (desert frogs exist) and normalize the impossible (weightless crates). factchk scans claims presented as reality-grounded, verifies each against external sources in both directions, and fixes or flags. Its scope is a claim about the world — whether what's asserted as real is real — not the soundness of a validation or the survival of a whole plan.
Workflow
- Scan for reality-grounded assertions — anything leaning on "this is plausible / realistic / absurd / novel / impossible because X," including the claim you are about to write, not only those already on the page.
- Verify each against external sources (web search, open references) in both directions: could the "absurd" be real? could the "obvious" or "novel" be false or long-established? If you cannot reach a source, flag — never assert from intuition.
- Fix or flag: a mechanically-clear error (a wrong date, a misattributed source, a falsified number) → correct it with a cited source; a judgment call (a contested or interpretive claim) → surface it, don't silently rewrite.
- Report each claim, its verdict, the source, and — for a failed claim — which direction it failed.
Rules
- Target claims asserted as reality-grounded, never deliberate fiction ("in our world, boxes float" is a declared choice). When it is unclear whether a claim is an in-world choice or a real-world assertion, flag, don't fix — the hardest call in the skill.
- Flagging only the unrealistic catches half the errors.
- The trigger is metacognition, not knowledge: you can't know every domain, so the moment you are about to assert a checkable fact from a feeling, verify it instead of trusting the feeling.
- A pass that finds nothing changes nothing.
Verification
Before finishing: every verdict traces to a citable external source, not a reworded prior intuition — and the report reads as fixes-vs-flags, not restated intuitions.