diff --git a/docs/research/2026-09-01-overhaul/s4-depth-alpha-packet.md b/docs/research/2026-09-01-overhaul/s4-depth-alpha-packet.md
index 6d0f9a17..aa355f3b 100644
--- a/docs/research/2026-09-01-overhaul/s4-depth-alpha-packet.md
+++ b/docs/research/2026-09-01-overhaul/s4-depth-alpha-packet.md
@@ -1768,3 +1768,34 @@ Only `ParticleRenderer.cs`, `WalkFrameDriverTests.cs`, this packet, and the
 S4-c3a plan-ledger row changed. AP rows, queue/router/pipeline/shader/manifest/
 package behavior, and installed content remain unchanged. No graphical client
 was launched.
+
+## 21. Owner-authorized evidence-only exception (2026-09-04)
+
+The owner explicitly authorized one correction beyond the five-attempt/
+third-round stop: fix the sole false mutation-first-failure sentence and run
+a narrow confirmation. This does not reopen renderer implementation or any
+other evidence claim.
+
+The exact correction is §18.7 mutation 9. Renaming AP-241 makes
+`register.IndexOf("| AP-241 |")` return `-1`; the first failure is the AP-table
+boundary `Assert.True` in
+`WorldAlphaCyptDocumentationAndRegister_PinPerCellTruthAndThreeResiduals`, not
+the later `Assert.Single`. Replace only that statement. The correction commit
+body must explicitly supersede the same false mutation-9 sentence in initial
+candidate commit `44e2bc227b`; do not rewrite that historical commit.
+
+Allowed files: this packet and the S4-c3a plan-ledger row only. No production,
+test, register, handoff, architecture, inventory, shader, manifest, or package
+file changes. The narrow gate is:
+
+1. temporarily rename the AP-241 table row, run only
+   `WorldAlphaCyptDocumentationAndRegister_PinPerCellTruthAndThreeResiduals`,
+   and record the actual first failure/message;
+2. restore the row exactly, rerun the same test and require 1/1 PASS;
+3. `git diff --check` and exact changed-file inspection;
+4. one narrow independent gate-honesty re-review of this exception diff only.
+
+No full renderer rerun is required: the final retail and production lenses
+already found no other correction-worthy item and the correction cannot affect
+compiled source or tests. A narrow PASS unlocks landing the already-reviewed
+c3a stack; a narrow FAIL returns to STOPPED UNLANDED.