diff --git a/SKILL.md b/SKILL.md
index 2570647..3407684 100644
--- a/SKILL.md
+++ b/SKILL.md
@@ -142,7 +142,10 @@ in the session.
 
 Distinguish a real fork from a default. "Should I use the conventional thing" is
 not a question. "3-5 are not decisions," as the operator put it, is the failure
-of asking about non-decisions.
+of asking about non-decisions. Weigh proportion too: a fork that guards only
+against the project's own code, such as how strictly to enforce an internal
+tripwire, gets a default and a recorded follow-up. Asked how much one such
+question mattered, the operator said not at all.
 
 ### 3. Hands executes one cut
 
diff --git a/references/briefs.md b/references/briefs.md
index 9bf26fe..f1f6002 100644
--- a/references/briefs.md
+++ b/references/briefs.md
@@ -90,6 +90,15 @@ it reported was fiction.
 When a cut deletes, list every rule that had a test before and has none after.
 A rule that still exists in code with its only test deleted is the failure mode
 of subtraction; either the rule goes too, or it gets a test in the same cut.
+Long jobs: wait for them and finish. Never end the turn with a to-do list in
+place of a report.
+Mutations: restore with a reverse edit or run against committed code; `git
+checkout` also reverts uncommitted fix code and silently invalidates the run.
+Warnings: measure from a forced rebuild and compare distinct messages; cargo
+replays warnings only when it actually rebuilds.
+Semantic properties ("exactly one call site", "this step actually runs"):
+prefer a semantic tool (a Clippy lint, the type system) over a text scanner,
+or state the scanner's limits in the test itself.
 
 Commits:
 - Small and pushed.
@@ -147,6 +156,17 @@ Falsify specifically:
   including ones that are not plain reverts>
 - <the layer where the invariant really fails: wire bytes, another runtime's
   decoder, the editor, the compiler, a legacy file decoded independently>
+- <for a sealed or private boundary: attack constructibility from an external
+  scratch crate or consumer, not path privacy. Try every public constructor the
+  language gives away: Deserialize and other derives, Default/From impls,
+  public fields, functions returning mutable references. A compile_fail test
+  pins a name; on stable rustc it does not even pin the error code>
+- <for rejection tests: forgeries must be shaped like real values (same length,
+  prefix, case and alphabet), or a weakened comparison passes them all>
+- <for any text scanner, grep assertion or line pin: try evasions (aliases,
+  function values, formatting, control flow around the pinned text such as
+  `if false` or `true ||`). A scanner is a tripwire with stated limits, not
+  proof of a semantic property>
 - <leftover greps>
 - rerun the builds, tests and captures yourself
 
diff --git a/references/changelog.md b/references/changelog.md
index 582ba59..af20a7e 100644
--- a/references/changelog.md
+++ b/references/changelog.md
@@ -2,6 +2,34 @@
 
 Record each change to the skill together with the evidence that motivated it.
 
+## 2026-09-16: sealing, forgeries, scanners and proportion, from Ghostlight L0
+
+Evidence: Ghostlight `docs/architecture/ghostlight-library-extraction-postmortem.md`
+and its cut map.
+
+- **Soul attacks constructibility, not names.** Ruling Q1-4 said sealed
+  constructors must be unreachable. Ten compile_fail doc-tests passed while
+  every public ID type derived `Deserialize`, so an external crate built any of
+  them from JSON; an ID-minting `Default` impl left all ten green. It was found
+  only because Self added the serde route to the Soul brief by hand. On stable
+  rustc the compile_fail error codes are not enforced either.
+- **Rejection tests need realistic forgeries.** Short fake digests passed
+  against kernels comparing only length, a prefix, all but the last character,
+  case-insensitively, or only the hex after the label. Five mutants survived
+  across two Soul passes.
+- **Text scanners are tripwires.** Every one written in the campaign lost to a
+  short evasion: a single-minter count to an alias, a subdirectory, a type
+  alias and a function value; a deploy wiring test to a two-line deletion that
+  reattached the pinned line to the wrong container, and its fix to `if false`
+  around exact lines. Prefer a semantic tool, or state the limits.
+- **Default proportionate forks.** Asked how much the single-minter enforcement
+  question mattered, the operator said not at all. A fork that guards only
+  against the project's own code is a default plus a recorded follow-up.
+- **Hands brief additions:** wait for long jobs instead of reporting a to-do
+  list (one Hands agent did); restore mutations without `git checkout` (one
+  run was invalidated that way); measure warnings from forced rebuilds (a
+  cached build reported zero).
+
 ## 2026-09-16: subtraction rules, from the Eureka campaign's own cuts
 
 - **A deletion can take a live rule's only test with it.** Cut 4 deleted a store