diff --git a/README.md b/README.md
index 08d7d55..873ba36 100644
--- a/README.md
+++ b/README.md
@@ -467,7 +467,10 @@ them. We provide:
 - `script/check` — run test, lint, and fmt-check
 - `script/docker` — build the Docker image tagged via
   `script/projectname`
-- `script/cibuild` — CI entrypoint: plain `docker build .`
+- `script/cibuild` — CI entrypoint: `docker build` with
+  `--no-cache-filter=lint,builder`, forcing the lint and test stages to
+  run on every invocation, because a cached build lints nothing and
+  queries no DNS
 - `script/precommit` — run by the git pre-commit hook; `go mod tidy`
   guard, then `script/check`
 - `script/install-precommit` — install the git pre-commit hook
diff --git a/TODO.md b/TODO.md
index 10c50d2..332b9cd 100644
--- a/TODO.md
+++ b/TODO.md
@@ -23,6 +23,8 @@ Rationale, Design, TODO, License, Author) if any are still missing.
 
 # Completed Steps
 
+- 2026-09-21: `script/cibuild` and `script/docker` now pass
+  `--no-cache-filter=lint,builder` so lint and tests run every build.
 - 2026-09-28: the server timeout test now drives `Run` and checks the
   `http.Server` it serves carries the timeouts; corrected the `ReadTimeout`
   note in that test (closes #120).
diff --git a/script/cibuild b/script/cibuild
index 1b9e57d..7ae48f0 100755
--- a/script/cibuild
+++ b/script/cibuild
@@ -1,14 +1,19 @@
 #!/bin/sh
 # script/cibuild: run the CI build. The Dockerfile's lint stage runs
 # make fmt-check and golangci-lint; its builder stage runs make test
-# and make build. A successful build implies all of those passed.
+# and make build.
+#
+# --no-cache-filter=lint,builder forces both of those stages to run on
+# every invocation. Without it an unchanged tree serves them from the
+# layer cache, reporting success having linted nothing and queried no
+# live DNS. A successful build then implies those stages actually ran.
 set -eu
 
 ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
 
 main() {
     cd "$ROOT"
-    docker build .
+    docker build --no-cache-filter=lint,builder .
 }
 
 main "$@"
diff --git a/script/docker b/script/docker
index 9b9ea86..794eb5a 100755
--- a/script/docker
+++ b/script/docker
@@ -1,6 +1,11 @@
 #!/bin/sh
 # script/docker: build the Docker image tagged with the project name.
-# Identical in all repos; the tag comes from script/projectname.
+# The tag comes from script/projectname.
+#
+# --no-cache-filter=lint,builder forces the lint stage and the builder
+# stage (make test) to run on every invocation. Without it an unchanged
+# tree serves them from the layer cache, producing an image whose build
+# linted nothing and queried no live DNS.
 set -eu
 
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
@@ -8,7 +13,7 @@ ROOT="$(cd "$SCRIPT_DIR/.." && pwd -P)"
 
 main() {
     cd "$ROOT"
-    docker build -t "$("$SCRIPT_DIR/projectname")" .
+    docker build --no-cache-filter=lint,builder -t "$("$SCRIPT_DIR/projectname")" .
 }
 
 main "$@"