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+# Cheapest Disconfirming Test
+
+Every serious claim in Open Problem Lab should identify the cheapest test that could make the repository lower confidence in it.
+
+This is not a demand for perfect certainty. It is a demand for an explicit reversal path.
+
+## Why this matters
+
+AI-assisted research makes it easy to produce plausible claims and expensive-looking evidence packages. The harder question is usually missing:
+
+> What would change our mind?
+
+Without that question, the protocol can drift into verification theater: sources are cited, schemas pass, prose sounds careful, but no one knows the smallest observation that would weaken the claim.
+
+A claim that cannot name its cheapest disconfirming test is usually not ready to become load-bearing repository knowledge.
+
+## Definition
+
+A cheapest disconfirming test is the lowest-cost safe check that would materially reduce confidence in a claim if it failed.
+
+It should be:
+
+- **specific** — tied to one claim, not a vague research agenda;
+- **safe** — does not require unsafe action or misuse;
+- **cheap** — uses the smallest credible check before larger work;
+- **decision-relevant** — failure would change status, scope, priority, or confidence;
+- **auditable** — another contributor can see what was tested and why it matters.
+
+Cheap does not mean weak. It means the project should try to falsify claims efficiently before spending reviewer attention, compute, field access, or money.
+
+## Minimum field
+
+Add this field to issue descriptions, PR bodies, evidence records, or review notes when a claim is intended to become canonical:
+
+```markdown
+**Cheapest disconfirming test:**
+If [specific check] shows [specific failure condition], then this claim should be [narrowed / disputed / rejected / moved to exploratory / sent for replication].
+```
+
+Examples of acceptable shapes:
+
+- If the same method fails on a second dated source set, the claim should be marked disputed.
+- If the effect disappears after excluding a known biased dataset, the claim should be narrowed to the original dataset only.
+- If a field reviewer identifies a routine operational constraint that blocks implementation, the claim should become field-pending rather than accepted.
+- If a reproduction run cannot recover the reported metric within the declared tolerance, the artifact should become replication-pending.
+
+## Bad patterns
+
+Bad tests are vague, heroic, or unfalsifiable.
+
+Avoid:
+
+- "More research is needed."
+- "An expert should review this someday."
+- "If the whole literature changes, update it."
+- "If someone proves it wrong."
+- "Run a large trial" when a source check, data audit, or small reproduction would test the load-bearing assumption first.
+
+The point is to name the first useful crack, not the final definitive study.
+
+## Reviewer rule
+
+A reviewer may ask for a cheapest disconfirming test before accepting a claim as canonical.
+
+The reviewer should especially ask for it when:
+
+- the claim is safety-sensitive;
+- the claim is quantitative;
+- the claim affects prioritization;
+- the claim is based on indirect evidence;
+- the claim depends on a narrow dataset, geography, population, or operational assumption;
+- an agent-generated submission sounds more confident than its evidence.
+
+## Agent rule
+
+Before opening a PR, an agent should identify the load-bearing assumption in its own claim and propose the cheapest safe way to attack it.
+
+The agent should write:
+
+1. The claim I want accepted is ...
+2. The load-bearing assumption is ...
+3. The cheapest disconfirming test is ...
+4. If that test fails, the claim should become ...
+
+If the agent cannot complete those lines, it should not present the claim as accepted knowledge.
+
+## Relationship to counter-evidence
+
+The disconfirming test is forward-looking: it says what would lower confidence next.
+
+The counter-evidence ledger is backward-looking: it records what has already weakened, bounded, or disputed a claim.
+
+Together, they prevent the repo from accumulating claims with no memory and no reversal path.
+
+## Acceptance test
+
+A cheapest disconfirming test is good when a skeptical reviewer can say:
+
+> This is the first safe thing I would check if I wanted to prove the claim too broad, too weak, or not yet ready.
+
+If the test would not change anything, it is not a disconfirming test. It is decoration.