diff --git a/Cargo.lock b/Cargo.lock
index 2c8ea27b4..e8a8bf1b9 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -643,7 +643,7 @@ checksum = "d6790f58c7ff633d8771f42965289203411a5e5c68388703c06e14f24770b41e"
 
 [[package]]
 name = "paredit-cli"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "assert_cmd",
  "blake3",
@@ -742,7 +742,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-core-cli"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "blake3",
  "cap-std",
@@ -763,7 +763,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-core-config"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-syntax",
  "serde_json",
@@ -772,7 +772,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-core-edit"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-semantics",
  "paredit-core-syntax",
@@ -782,7 +782,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-core-jsonrpc"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "serde_json",
  "thiserror",
@@ -790,7 +790,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-core-lint-engine"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-safety",
  "paredit-core-semantics",
@@ -801,7 +801,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-core-safety"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "blake3",
  "paredit-core-syntax",
@@ -812,7 +812,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-core-semantics"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-syntax",
  "proptest",
@@ -821,7 +821,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-core-syntax"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "proptest",
  "thiserror",
@@ -830,7 +830,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-core-workspace"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "blake3",
  "cap-std",
@@ -843,7 +843,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-binding"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -860,7 +860,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-change-summary"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -871,7 +871,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-code-metrics"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -881,7 +881,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-conditional-conversion"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -895,7 +895,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-data-report"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -905,11 +905,11 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-editor"
-version = "1.6.1"
+version = "1.6.2"
 
 [[package]]
 name = "paredit-feature-emacs-lisp"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-lint-engine",
  "paredit-core-semantics",
@@ -918,7 +918,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-external-check"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -930,7 +930,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-extract"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -944,7 +944,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-form-transform"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -959,7 +959,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-function-parameter"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -974,7 +974,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-generate"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -986,7 +986,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-inline"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1001,7 +1001,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-binding-analysis"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-lint-engine",
  "paredit-core-semantics",
@@ -1010,7 +1010,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-build-system"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1021,7 +1021,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-call-shape"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1032,7 +1032,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-carp-idiom"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-lint-engine",
  "paredit-core-syntax",
@@ -1040,7 +1040,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-clojure-depth"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1051,7 +1051,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-clojure-idiom"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1062,7 +1062,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-compile-time"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1073,7 +1073,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-concurrency"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1084,7 +1084,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-condition-depth"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-lint-engine",
  "paredit-core-syntax",
@@ -1092,7 +1092,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-condition-system"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1103,7 +1103,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-conditional"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1118,7 +1118,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-contract-annotation"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1129,7 +1129,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-control-flow"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1144,7 +1144,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-convention"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-lint-engine",
  "paredit-core-syntax",
@@ -1152,7 +1152,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-custom"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-lint-engine",
  "paredit-core-syntax",
@@ -1161,7 +1161,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-data-structure"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-cli",
  "paredit-core-lint-engine",
@@ -1172,7 +1172,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-destructive-sequence"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-lint-engine",
  "paredit-core-syntax",
@@ -1180,7 +1180,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-documentation"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-lint-engine",
  "paredit-core-syntax",
@@ -1188,7 +1188,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-elisp-depth"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-lint-engine",
  "paredit-core-syntax",
@@ -1196,7 +1196,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-elisp-idiom"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-lint-engine",
  "paredit-core-syntax",
@@ -1204,7 +1204,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-fennel-janet-depth"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-lint-engine",
  "paredit-core-syntax",
@@ -1212,7 +1212,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-fennel-janet-idiom"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-lint-engine",
  "paredit-core-syntax",
@@ -1220,7 +1220,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-form-shape"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1236,7 +1236,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-generic-dispatch"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-lint-engine",
  "paredit-core-syntax",
@@ -1244,7 +1244,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-hy-depth"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-lint-engine",
  "paredit-core-syntax",
@@ -1252,7 +1252,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-hy-lfe-idiom"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-lint-engine",
  "paredit-core-syntax",
@@ -1260,7 +1260,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-introspection"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1271,7 +1271,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-iteration-flow"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1282,7 +1282,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-lfe-carp-depth"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-lint-engine",
  "paredit-core-syntax",
@@ -1290,7 +1290,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-loop-facility"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-lint-engine",
  "paredit-core-syntax",
@@ -1298,7 +1298,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-macro-authoring"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-cli",
  "paredit-core-lint-engine",
@@ -1308,7 +1308,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-numeric"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1323,7 +1323,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-object-system"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1334,7 +1334,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-package-hygiene"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1345,7 +1345,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-pathname-io"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-lint-engine",
  "paredit-core-syntax",
@@ -1353,7 +1353,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-performance"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-lint-engine",
  "paredit-core-syntax",
@@ -1361,7 +1361,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-portability"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-lint-engine",
  "paredit-core-syntax",
@@ -1369,7 +1369,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-racket-depth"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-cli",
  "paredit-core-lint-engine",
@@ -1379,7 +1379,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-repl-debug"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1393,7 +1393,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-safety"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-lint-engine",
  "paredit-core-syntax",
@@ -1401,7 +1401,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-scheme-idiom"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1415,7 +1415,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-sequence"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1430,7 +1430,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-string-char"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1445,7 +1445,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-testing"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1456,7 +1456,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lint-type-declaration"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "paredit-core-lint-engine",
  "paredit-core-syntax",
@@ -1464,7 +1464,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-lisp-analysis"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1475,7 +1475,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-migrate"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1486,7 +1486,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-package"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1501,7 +1501,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-project-analysis"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1518,7 +1518,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-project-inventory"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1528,7 +1528,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-query"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1538,7 +1538,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-refactor-workflow"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "blake3",
  "cap-std",
@@ -1560,7 +1560,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-remove-unused"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1578,7 +1578,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-rename"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1593,7 +1593,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-schema-check"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1604,7 +1604,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-selector"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1614,7 +1614,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-semantic-report"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "clap",
  "paredit-core-cli",
@@ -1625,7 +1625,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-similarity"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "blake3",
  "clap",
@@ -1640,7 +1640,7 @@ dependencies = [
 
 [[package]]
 name = "paredit-feature-structural-diff"
-version = "1.6.1"
+version = "1.6.2"
 dependencies = [
  "blake3",
  "clap",
diff --git a/Cargo.toml b/Cargo.toml
index b2997fd26..3130a8198 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "paredit-cli"
-version = "1.6.1"
+version = "1.6.2"
 edition = "2024"
 publish = false
 rust-version = "1.85"
@@ -243,7 +243,7 @@ exclude = ["fuzz", "xtask"]
 default-members = [".", "packages/*/*"]
 
 [workspace.package]
-version = "1.6.1"
+version = "1.6.2"
 edition = "2024"
 rust-version = "1.85"
 license = "MIT"
diff --git a/docs/src/getting-started.md b/docs/src/getting-started.md
index d93e887c8..1e851abc5 100644
--- a/docs/src/getting-started.md
+++ b/docs/src/getting-started.md
@@ -66,9 +66,9 @@ The examples above follow the latest default branch. For CI, production
 automation, or a reproducible developer environment, pin a release tag:
 
 ```sh
-nix run github:nerima-lisp/paredit-cli/v1.6.1 -- --help
-nix profile install github:nerima-lisp/paredit-cli/v1.6.1
-cargo install --git https://github.com/nerima-lisp/paredit-cli --tag v1.6.1 --locked
+nix run github:nerima-lisp/paredit-cli/v1.6.2 -- --help
+nix profile install github:nerima-lisp/paredit-cli/v1.6.2
+cargo install --git https://github.com/nerima-lisp/paredit-cli --tag v1.6.2 --locked
 ```
 
 A tag is the release artifact — the crate is not published to a package
diff --git a/docs/src/reference/compatibility.md b/docs/src/reference/compatibility.md
index a6c8d090b..69441d48c 100644
--- a/docs/src/reference/compatibility.md
+++ b/docs/src/reference/compatibility.md
@@ -93,9 +93,9 @@ The crate is not published to a package registry, so pin the tag — or a
 reviewed commit — in whichever channel you use:
 
 ```sh
-nix run github:nerima-lisp/paredit-cli/v1.6.1 -- --help
-nix profile install github:nerima-lisp/paredit-cli/v1.6.1
-cargo install --git https://github.com/nerima-lisp/paredit-cli --tag v1.6.1 --locked
+nix run github:nerima-lisp/paredit-cli/v1.6.2 -- --help
+nix profile install github:nerima-lisp/paredit-cli/v1.6.2
+cargo install --git https://github.com/nerima-lisp/paredit-cli --tag v1.6.2 --locked
 ```
 
 Release notes must call out anything that affects automation: new or
diff --git a/packages/feature/lint-fennel-janet-depth/src/cost_tests.rs b/packages/feature/lint-fennel-janet-depth/src/cost_tests.rs
index 2e34be582..db4c99406 100644
--- a/packages/feature/lint-fennel-janet-depth/src/cost_tests.rs
+++ b/packages/feature/lint-fennel-janet-depth/src/cost_tests.rs
@@ -25,7 +25,35 @@
 //!
 //! Absolute nanoseconds from this machine are worthless: the audit ran with a
 //! load average above 10 and several sibling agents building in parallel. The
-//! assertions are all *ratios*, and the printed table is for the report.
+//! printed table is for the report.
+//!
+//! # What runs unattended
+//!
+//! Two things, both with enough headroom that machine load cannot decide them:
+//!
+//! - the **invocation counts**, which the head index and the dialect scope fix
+//!   before any `check` body runs, so they are identical idle and loaded;
+//! - the **gap to [`materializing::RULE`]**, which is four orders of magnitude
+//!   (measured 9,000x in release, 13,000x in dev) against a 10x floor. This is
+//!   the assertion that actually catches a guard moved above its domain check.
+//!
+//! The **per-call doubling ratio is a benchmark, not a test**, and is
+//! `#[ignore]`d — see [`ignored_bench_per_call_cost_does_not_grow_with_the_file`].
+//! It was asserted at `< 1.8` and failed a downstream `nix` build at 2.04 on
+//! untouched code. Two reasons it cannot be a gate:
+//!
+//! - the real rules cost 16-75 ns per call in a release build, so the ratio of
+//!   two such measurements is mostly scheduler noise;
+//! - doubling the file doubles the tree, so the traversal's working set stops
+//!   fitting in cache. That is constant work per call taking more time per
+//!   call, and it puts the idle-machine ratio at ~1.27 in release before any
+//!   contention — most of the budget spent on an effect that is not a
+//!   complexity change at all.
+//!
+//! The property it was reaching for is not lost: a `check` that materializes
+//! the document is what
+//! [`every_rule_stays_far_cheaper_than_a_materializing_one`] measures directly,
+//! against a control built to have that exact shape.
 
 use std::path::Path;
 use std::time::Duration;
@@ -315,68 +343,86 @@ fn every_rule_stays_far_cheaper_than_a_materializing_one() {
     );
 }
 
-/// Doubling the file must not change what one `check` call costs.
+/// Every rule is dispatched once per occurrence of one of its heads, and no
+/// more — so doubling the file doubles the dispatches rather than squaring
+/// them.
 ///
-/// This is deliberately expressed as **ns per call across two file sizes**
-/// rather than as a ratio of totals. Both say the same thing when the totals
-/// are large, but the totals here are not: at 27-160 ns per call the real
-/// rules are near the clock's resolution, so their totals swing with the
-/// scheduler while their per-call cost does not.
+/// **Counts, not wall clock.** The head index and the dialect scope decide
+/// these before any `check` body runs, so a loaded machine reports exactly
+/// what an idle one does. A rule invoked more often than its heads occur is
+/// one re-walking the document per match, which is the dispatch-side shape of
+/// the same defect [`every_rule_stays_far_cheaper_than_a_materializing_one`]
+/// catches on the cost side.
+#[test]
+fn each_rule_is_dispatched_once_per_head_occurrence() {
+    // Heads per repetition of the two fixtures, in `COST_ENTRIES` order:
+    //
+    //   fennel-bad-unpack                        9  DENSE_FENNEL
+    //   fennel-nested-associative-operator       5  DENSE_FENNEL
+    //   fennel-redundant-do                      7  `fn` `when` `let` `each`
+    //                                               `for` `while` `lambda`
+    //   janet-dead-branch-on-constant-condition  4  `when` `unless` `if` `if-not`
+    //   janet-unreachable-match-clause           1  `match`
+    //   reference-materializing                  1  `when`, Fennel only
+    const PER_REPETITION: [u64; 6] = [9, 5, 7, 4, 1, 1];
+
+    let counts = |repetitions: usize| -> Vec<u64> {
+        measure_once(repetitions)
+            .into_iter()
+            .map(|item| item.invocations)
+            .collect()
+    };
+
+    for repetitions in [200, 400] {
+        let observed = counts(repetitions);
+        let expected: Vec<u64> = PER_REPETITION
+            .iter()
+            .map(|per| per * repetitions as u64)
+            .collect();
+        assert_eq!(
+            observed, expected,
+            "invocations must equal head occurrences at {repetitions} \
+             repetitions; a rule dispatched more often than its heads occur is \
+             being handed nodes its head filter should have excluded"
+        );
+    }
+}
+
+/// The per-call doubling ratio, as a benchmark rather than a gate.
+///
+///     cargo test -p paredit-feature-lint-fennel-janet-depth --release \
+///       --lib -- --ignored --nocapture ignored_bench_per_call
 ///
-/// The property is exact. A rule whose `check` is O(depth) costs the same per
-/// call whatever the file size, so its ratio sits at 1. A rule that
-/// materializes the document inside `check` is O(file) per call, so doubling
-/// the file doubles its per-call cost — which is precisely what separates
-/// `reference-materializing` (measured at 2.2) from every rule in this
-/// package (measured at 0.5 to 1.3).
+/// A `check` that is O(depth) costs the same per call whatever the file size;
+/// one that materializes the document is O(file) per call, so doubling the
+/// file doubles it. That is the difference between `reference-materializing`
+/// and every rule here, and it is worth reading whenever a rule changes.
+///
+/// It is not worth failing a build on. See the module docs: at 16-75 ns per
+/// call in release the ratio is dominated by scheduler noise and by cache
+/// working-set growth, and asserting it at `< 1.8` broke a downstream `nix`
+/// build at 2.04 on code nobody had touched.
 #[test]
-fn a_rules_per_call_cost_does_not_grow_with_the_file() {
+#[ignore = "a benchmark: wall-clock ratios are unstable under parallel load"]
+fn ignored_bench_per_call_cost_does_not_grow_with_the_file() {
     let small = measure_both(200);
     let large = measure_both(400);
 
-    let ratio_of = |name: &str| -> f64 {
-        let find = |set: &[Measured]| -> f64 {
-            set.iter()
-                .find(|item| item.name == name)
-                .map(|item| item.per_call)
-                .expect("rule present")
-        };
-        find(&large) / find(&small).max(1.0)
+    let find = |set: &[Measured], name: &str| -> f64 {
+        set.iter()
+            .find(|item| item.name == name)
+            .map(|item| item.per_call)
+            .expect("rule present")
     };
 
     for entry in &COST_ENTRIES {
         let name = entry.meta().name().as_str();
-        if name == "reference-materializing" {
-            continue;
-        }
-        let ratio = ratio_of(name);
-        assert!(
-            ratio < 1.8,
-            "{name} cost {ratio:.2}x as much per call on a file twice the \
-             size; a `check` that is O(file) rather than O(depth) is the usual \
-             cause, and calling is_unevaluated_* before the domain check is \
-             how that happens"
+        let at_small = find(&small, name);
+        let at_large = find(&large, name);
+        eprintln!(
+            "{name}: {at_small:.0} ns/call @200 → {at_large:.0} ns/call @400, \
+             ratio {:.2}",
+            at_large / at_small.max(1e-9)
         );
     }
-
-    // The control. Without it the test above passes just as happily when the
-    // measurement is broken and every ratio is 1.
-    //
-    // Stated as an absolute magnitude rather than as the reference rule's own
-    // doubling ratio. The ratio is theoretically 2 but was observed between
-    // 1.48 and 2.96 across runs on this machine: taking the best of five
-    // samples pulls the *small* file's number down hardest, which compresses
-    // it. Six orders of magnitude between the two shapes is not compressible
-    // by any amount of scheduler noise.
-    let reference = large
-        .iter()
-        .find(|item| item.name == "reference-materializing")
-        .expect("rule present");
-    assert!(
-        reference.per_call > 100_000.0,
-        "the reference rule cost only {:.0} ns per call; it materializes the \
-         whole document on every one of them, so either the fixture stopped \
-         matching `when` or the measurement is not live",
-        reference.per_call
-    );
 }