Merge remote-tracking branch 'origin/human/r1-register-reclassification' into auto/frame-blend-draw-path

docs/agents/PROTOCOL.md

@@ -133,6 +133,42 @@ Refutation is cheapest where the other agent is most confident. Prefer:
 centroid estimator that is 19.8° out on a known rotation cannot measure an
 unknown one. A filter that fails its own known-positive is dead, not tuneable.
 
+⚠️ **And a control verifies CAPABILITY, not CONFIGURATION.** Both agents ran
+controls and both were still wrong: one tested whether the method *can* detect a
+blend difference, not whether *that run* had `blend_mode` set — it was left at
+the engine default. The other tested whether NDC→pixel conversion is right, not
+whether the dump captured all six quads; it captured two, with a well-formed line
+and no ellipsis. Assert the run's configuration, not just the method's power.
+
+### R1 — a refutation is only as good as its instrument
+
+**A refutation whose instrument is one of our renderers is not a refutation.** It
+is *"our renderer disagrees"* — 🟡, not ❌.
+
+Agreed by both agents 2026-08-31, applied to
+[`../re/REFUTED.md`](../re/REFUTED.md) by the human on 2026-09-01. The register
+is not yours to reclassify: it is the file you both read to decide what *not* to
+try, and two agents agreeing is not the authority for changing it. Propose;
+do not enact.
+
+What this asks of you, in practice:
+
+* **Every claim you retire names its instrument** — `⟨capture⟩`, `⟨disc⟩`,
+  `⟨image⟩`, `⟨render-vs-capture⟩`, `⟨harness⟩`… The register's reading guide
+  holds the vocabulary and says which tags are ours.
+* **When you improve a renderer, a reader or the harness, run
+  `tools/stale-instrument <that instrument>`.** It lists what that instrument
+  killed. Those claims re-open. This is the mechanism the rule exists for: the
+  motivating failure was not that anyone was careless, it is that **nothing
+  re-opened a claim when the instrument that killed it improved**, and a real
+  disc field sat dead for weeks as a result.
+* **A 🟡 carries what would settle it.** A re-opened claim with no next
+  experiment is an unanswered question wearing a colour.
+
+The exception, from R5: our tool is the right instrument for a question **about
+our tool**. *"Can `screen render` draw the developer splash?"* is ours to answer.
+*"What does the game draw?"* is not.
+
 **Disagreements escalate to the human with both positions.** They are not
 resolved by seniority, by who wrote it down first, or by whoever is more certain.