diff --git a/.tangled/workflows/check.yml b/.tangled/workflows/check.yml
index 81a2d38f..5982ee20 100644
--- a/.tangled/workflows/check.yml
+++ b/.tangled/workflows/check.yml
@@ -21,6 +21,14 @@ clone:
 
 dependencies:
   nixpkgs:
+    # Shell gates are intentionally explicit: Nixery's base image does not
+    # provide the normal Unix text/file utilities.
+    - bash
+    - coreutils
+    - findutils
+    - gawk
+    - gnugrep
+    - gnused
     - rustc
     - cargo
     - rustfmt
diff --git a/tools/check.sh b/tools/check.sh
index 14becb6c..6c04fc5b 100755
--- a/tools/check.sh
+++ b/tools/check.sh
@@ -152,6 +152,27 @@ for script in tools/check.sh tools/corpus_gate.sh tools/wiki_gate.sh tools/seed-
   bash -n "$script" || { echo "FAIL: shell syntax: $script"; fail=1; }
 done
 
+step "gate dependency preflight"
+bash_bin=$(command -v bash)
+partial_path=$(mktemp -d)
+for available_command in comm dirname head mktemp rm sort tr wc; do
+  command_path=$(command -v "$available_command" || true)
+  [ -n "$command_path" ] || continue
+  ln -s "$command_path" "$partial_path/$available_command"
+done
+for gate in tools/corpus_gate.sh tools/wiki_gate.sh; do
+  if gate_output=$(PATH="$partial_path" "$bash_bin" "$gate" 2>&1); then
+    echo "FAIL: $gate returned success without its required commands"
+    fail=1
+  elif ! grep -q '^FAIL: required command unavailable:' <<< "$gate_output"; then
+    echo "FAIL: $gate did not fail through its command preflight"
+    fail=1
+  else
+    echo "$gate: rejects missing dependencies"
+  fi
+done
+rm -rf "$partial_path"
+
 # Docs gates run in parallel with each other (and with the Rust gate when
 # both are needed). They never take the rust flock.
 docs_pids=()
@@ -173,6 +194,8 @@ step "docs gates (parallel)"
 start_docs_gate "corpus" "bash tools/corpus_gate.sh"
 start_docs_gate "wiki" "bash tools/wiki_gate.sh"
 start_docs_gate "ledger-index" "bash tools/ledger_index.sh --check"
+# The single-quoted program is evaluated inside start_docs_gate, not here.
+# shellcheck disable=SC2016
 start_docs_gate "env-registry" '
   env_reg=wiki/engineering/env.md
   env_missing=0
diff --git a/tools/corpus_gate.sh b/tools/corpus_gate.sh
index 71bba06a..426c9211 100755
--- a/tools/corpus_gate.sh
+++ b/tools/corpus_gate.sh
@@ -3,7 +3,17 @@
 # Scans the wiki tree once per concern instead of re-grepping every file
 # for every field (the previous form was a fork storm under concurrent agents).
 set -uo pipefail
-cd "$(dirname "$0")/.."
+
+missing_commands=0
+for required_command in awk dirname find grep head mktemp rm sed sort tr wc; do
+  if ! command -v "$required_command" >/dev/null 2>&1; then
+    printf 'FAIL: required command unavailable: %s\n' "$required_command"
+    missing_commands=1
+  fi
+done
+[ "$missing_commands" -eq 0 ] || exit 1
+
+cd "$(dirname "$0")/.." || exit 1
 
 fail=0
 
@@ -30,7 +40,8 @@ tmp=$(mktemp -d)
 trap 'rm -rf "$tmp"' EXIT
 
 heading_slugs_file() {
-  local file="$1" cache="$tmp/headings.$(printf '%s' "$file" | tr '/ ' '__')"
+  local file="$1" cache
+  cache="$tmp/headings.$(printf '%s' "$file" | tr '/ ' '__')"
   if [ ! -f "$cache" ]; then
     # slugify_heading prints without a trailing newline; add one per heading
     # so the cache is line-oriented for grep -qxF.
diff --git a/tools/wiki_gate.sh b/tools/wiki_gate.sh
index df283639..1e50cab7 100755
--- a/tools/wiki_gate.sh
+++ b/tools/wiki_gate.sh
@@ -13,7 +13,17 @@
 # writing that exact bracket-paren shape in prose; describe the syntax in
 # words instead.
 set -uo pipefail
-cd "$(dirname "$0")/.."
+
+missing_commands=0
+for required_command in comm dirname find grep mktemp rm sed sort; do
+  if ! command -v "$required_command" >/dev/null 2>&1; then
+    printf 'FAIL: required command unavailable: %s\n' "$required_command"
+    missing_commands=1
+  fi
+done
+[ "$missing_commands" -eq 0 ] || exit 1
+
+cd "$(dirname "$0")/.." || exit 1
 
 fail=0
 tmp=$(mktemp -d)
diff --git a/wiki/log/2026-07-10-ci-gates-fail-closed.md b/wiki/log/2026-07-10-ci-gates-fail-closed.md
new file mode 100644
index 00000000..ddef7fd2
--- /dev/null
+++ b/wiki/log/2026-07-10-ci-gates-fail-closed.md
@@ -0,0 +1,49 @@
+# CI corpus gates fail closed
+
+```
+Type: log
+```
+
+## Intent
+
+Make remote corpus enforcement real: missing audit utilities must turn the
+Tangled job red instead of letting an empty scan report success.
+
+## Finding
+
+The Tangled run for the corpus-hardening landing displayed green even though
+its corpus and wiki steps printed `command not found` for `find`, `grep`, and
+`sed`. Nixery did not include the ordinary shell utilities implicitly. The
+scripts used `set -uo pipefail`, but the missing commands ran inside process
+substitutions and loops whose failures did not reach the final exit status, so
+both audits could scan nothing and report success.
+
+This was a process insecurity: the local gate was real, but the remote copy of
+the same gate could fail open.
+
+## Fix
+
+- Tangled's check image now explicitly installs Bash, coreutils, findutils,
+  gawk, GNU grep, and GNU sed.
+- `tools/corpus_gate.sh` and `tools/wiki_gate.sh` preflight every external
+  command they use and exit nonzero before scanning when one is unavailable.
+- `tools/check.sh --docs` constructs the CI-like partial `PATH` that caused the
+  false green and requires both scripts to reject it through that preflight.
+- The workflow knowledge page now states that a missing audit dependency is a
+  hard failure.
+
+## Verification
+
+- Reproduction before the fix: both gates exited 0 while printing missing
+  `find`/`grep`/`sed` errors.
+- Regression after the fix: both gates exit 1 and name the missing commands
+  under the same partial `PATH`.
+- `./tools/check.sh --docs` passes, including the new fail-closed regression
+  step and the normal corpus, wiki, and environment gates.
+- `shellcheck tools/check.sh tools/corpus_gate.sh tools/wiki_gate.sh` passes.
+
+## Design impact
+
+No game or corpus rule changed. This restores
+`wiki/process/meta.md` acceptance criterion 9 in the environment that was not
+actually enforcing it.
diff --git a/wiki/log/DEVLOG.md b/wiki/log/DEVLOG.md
index 543cc8f8..ceae84cb 100644
--- a/wiki/log/DEVLOG.md
+++ b/wiki/log/DEVLOG.md
@@ -30,6 +30,11 @@ add or amend a session log, then re-run the generator.
 - Intent: Cameron: mode change should be hover over a rack and press 1-4 immediately — not enter + enter + select dial row + enter.
 - Log: [wiki/log/2026-07-10-hover-mode-keys.md](2026-07-10-hover-mode-keys.md)
 
+## 2026-07-10 - CI corpus gates fail closed
+
+- Intent: Make remote corpus enforcement real: missing audit utilities must turn the Tangled job red instead of letting an empty scan report success.
+- Log: [wiki/log/2026-07-10-ci-gates-fail-closed.md](2026-07-10-ci-gates-fail-closed.md)
+
 ## 2026-07-10 - Bevy performance pass
 
 - Intent: The material frontend was paying full restyle/UI cost every display frame: `advance_sim` held `ResMut<Game>` and ticked a timer on `Game` every frame, so `game.is_changed()` stayed true and `restyle_3d` / `render_map` / `render_ui` rebuilt continuously.
diff --git a/wiki/process/workflows.md b/wiki/process/workflows.md
index 5ce77186..68d61dcc 100644
--- a/wiki/process/workflows.md
+++ b/wiki/process/workflows.md
@@ -165,7 +165,11 @@ rebase of every place that teaches, checks, or renders the authority model.
 The doorway is protected mechanically: `tools/corpus_gate.sh` bounds its size,
 forbids binding-page structure, validates every page role and spec header, and
 resolves every structured Design target and heading. Local checks and CI call
-this same script so the two implementations cannot drift.
+this same script so the two implementations cannot drift. Both corpus scripts
+preflight their external commands and fail before auditing if any are absent;
+the Tangled Nixery image explicitly supplies Bash, GNU text utilities,
+findutils, and coreutils. A missing audit dependency must make CI red, never
+turn an empty scan into a green result.
 
 ## Browsing the wiki