diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 1da843580..95d0c9661 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -69,6 +69,8 @@ jobs:
         run: bash tools/ci/copied-sources-check.sh
       - name: bash bodies in PowerShell job scripts pass bash -n, the lost-quote class (self-test first, then the tree)
         run: bash tools/ci/bash-body-check.sh --self-test && bash tools/ci/bash-body-check.sh
+      - name: run jobs test their fetched kit before use, the wiped-jobs-folder class (self-test first, then the tree)
+        run: bash tools/ci/kit-path-check.sh --self-test && bash tools/ci/kit-path-check.sh
       - name: pinned guest programs match their manifest and are built only by pin-guests.sh
         run: bash tools/ci/pinned-guests-check.sh
       - name: no secret file names and no 64-hex secrets in the tree (self-test first, then the tree)
diff --git a/packaging/README-ship.md b/packaging/README-ship.md
index 0d62e74a5..ceb69dae2 100644
--- a/packaging/README-ship.md
+++ b/packaging/README-ship.md
@@ -121,3 +121,7 @@ file and run), unescapes it the way PowerShell would, and runs `bash -n` on it.
 never passes CI before it runs, so `packaging/ota/publish-jobs.sh add --kind run` runs the same check (and
 `tools/ci/prover-socket-check.sh`, the root-socket class; `bash -n` for a `.sh` script) on the script before anything is
 signed, and refuses the publish with the check's output. `packaging/ota/test-publish-jobs.sh` proves the refusals.
+The wiped-jobs-folder class (5 October 2026, 21:49Z): an app install clears the jobs folder, so a run job that uses a kit
+fetched by an earlier fetch job tests the kit is there (Test-Path on the kit root or any file under it) before its first
+use, and the fetch is republished under a new id after any app update. `tools/ci/kit-path-check.sh` fails CI and the
+publish on a kit path used before that check.
diff --git a/packaging/ota/publish-jobs.sh b/packaging/ota/publish-jobs.sh
index 8d444d5ff..1d3c9d7d0 100755
--- a/packaging/ota/publish-jobs.sh
+++ b/packaging/ota/publish-jobs.sh
@@ -261,14 +261,17 @@ if [ "$CMD" = add ]; then
       # anything is signed. A failure refuses the publish with the check's output; a missing check refuses it too.
       # PowerShell: every inline bash body must parse (tools/ci/bash-body-check.sh, the lost-quote class; a body it
       # cannot read fails, never skips). Bash: the script itself must parse. Both: a root prover run kills the GPU
-      # server and unlinks its socket (tools/ci/prover-socket-check.sh, the root-socket class). A check file that is
-      # missing from this tree refuses too (bash exits 127 with the reason), so no job goes out unchecked.
+      # server and unlinks its socket (tools/ci/prover-socket-check.sh, the root-socket class), and a fetched kit under
+      # the jobs folder is tested before its first use (tools/ci/kit-path-check.sh, the wiped-jobs-folder class). A
+      # check file that is missing from this tree refuses too (bash exits 127 with the reason), so no job goes out
+      # unchecked.
       if [ "$SHELL_KIND" = powershell ]; then
         out="$(bash "$ROOT/tools/ci/bash-body-check.sh" "$SCRIPT" 2>&1)" || { echo "run: bash-body-check.sh refuses $SCRIPT:" >&2; printf '%s\n' "$out" >&2; exit 1; }
       else
         out="$(bash -n "$SCRIPT" 2>&1)" || { echo "run: bash -n refuses $SCRIPT (the lost-quote class):" >&2; printf '%s\n' "$out" >&2; exit 1; }
       fi
       out="$(bash "$ROOT/tools/ci/prover-socket-check.sh" "$SCRIPT" 2>&1)" || { echo "run: prover-socket-check.sh refuses $SCRIPT:" >&2; printf '%s\n' "$out" >&2; exit 1; }
+      out="$(bash "$ROOT/tools/ci/kit-path-check.sh" "$SCRIPT" 2>&1)" || { echo "run: kit-path-check.sh refuses $SCRIPT:" >&2; printf '%s\n' "$out" >&2; exit 1; }
       PARAMS="$(python3 -c 'import json,sys; print(json.dumps({"script": open(sys.argv[1]).read(), "shell": sys.argv[2], "elevated": sys.argv[3]=="1", "stop_miners_first": sys.argv[4]=="1", **({"timeout_minutes": int(sys.argv[5])} if sys.argv[5] else {})}))' "$SCRIPT" "$SHELL_KIND" "$ELEVATED" "$STOP_MINERS" "$TIMEOUT_MIN")"
       [ -n "$TITLE" ] || TITLE="run $(basename "$SCRIPT")"
       ;;
diff --git a/packaging/ota/test-publish-jobs.sh b/packaging/ota/test-publish-jobs.sh
index c5f8b545e..3f149f8fd 100755
--- a/packaging/ota/test-publish-jobs.sh
+++ b/packaging/ota/test-publish-jobs.sh
@@ -9,7 +9,8 @@
 # a new envelope; an envelope made by hand from the FIRST file and the SECOND signature (the stale pair an edge can
 # serve across a deploy) is REFUSED by the signer with the words the app logs; a tampered inner byte is refused;
 # `sign` rewrites all three consistently; a `run` script that fails a class check (a lost quote in an inline bash
-# body, a body the check cannot read, a bash script that does not parse, a root prover run without the socket cleanup)
+# body, a body the check cannot read, a bash script that does not parse, a root prover run without the socket cleanup,
+# a fetched kit used before a presence check)
 # is REFUSED before anything is signed and the envelope is left as it was; and the real OTA key is the key the app
 # embeds.
 #
@@ -112,6 +113,9 @@ expect_fail "a bash script with a lost quote" "$PUBLISH" add --kind run --target
 printf '& wsl.exe -d Ubuntu-24.04 -u root -- bash /mnt/c/prove.sh\n# igneum-prove-host --mode shard --shard 0\n' > "$T/root-prover.ps1"
 expect_fail "a root prover script without the socket cleanup" "$PUBLISH" add --kind run --target 1ccfe586 --script "$T/root-prover.ps1" --id test-root-socket --dest "$D" --base-url https://example.invalid/dl/t
 grep -q "prover-socket" "$T/out" && ok "refused by the socket check" || bad "another reason: $(tail -1 "$T/out")"
+printf '$jobs = Split-Path $env:IGNEUM_JOB_DIR\n$exe = Join-Path (Join-Path $jobs "fetch-kit-1") "worker.exe"\n& $exe --list\n' > "$T/kit-unchecked.ps1"
+expect_fail "a run script that uses a fetched kit before a presence check" "$PUBLISH" add --kind run --target 1ccfe586 --script "$T/kit-unchecked.ps1" --id test-kit-unchecked --dest "$D" --base-url https://example.invalid/dl/t
+grep -q "kit path used before a presence check" "$T/out" && ok "refused by the kit-path check" || bad "another reason: $(tail -1 "$T/out")"
 cmp -s "$T/before.signed" "$D/igneum-jobs.signed.json" && ok "a refused publish leaves the envelope untouched" || bad "a refused publish changed the envelope"
 
 echo "== the key"
diff --git a/tools/ci/fixtures/kit-path-ok.ps1 b/tools/ci/fixtures/kit-path-ok.ps1
new file mode 100644
index 000000000..14904f369
--- /dev/null
+++ b/tools/ci/fixtures/kit-path-ok.ps1
@@ -0,0 +1,25 @@
+# Fixture for tools/ci/kit-path-check.sh --self-test: both ways a run job reaches a fetched kit under the app's jobs
+# folder, each checked for presence before its first use. Must pass (2 kit paths). Never run; a stand-in for a job.
+$ErrorActionPreference = 'Continue'
+# the job's own folder always exists (the app made it for this run): not a kit path
+$job = $env:IGNEUM_JOB_DIR
+$jobFile = Join-Path $env:IGNEUM_JOB_DIR 'jobs.txt'
+# 1. the race-5090.ps1 shape: the jobs folder is the parent of this job's folder, the kit is a sibling job's folder
+$jobs = Split-Path $env:IGNEUM_JOB_DIR
+$fetched = Join-Path $jobs 'fetch-race-worker-20261004'
+$exe = Join-Path $fetched 'igneum-worker-cuda.exe'
+if (-not (Test-Path $exe)) { Write-Output "RESULT race worker missing at $exe (the fetch job runs first)"; exit 2 }
+& $exe --race --race-rounds 3 2>&1 | ForEach-Object { "RESULT $_" }
+# 2. the amd-card-test.ps1 shape: jobs\<KitJob>\kit under the app folder, a wait loop then the check; a sibling file
+#    under the same kit (pack-a) is covered by the check on the worker
+$KitJob = 'amd-kit-1'
+$kit = Join-Path $env:IGNEUM_APP_DIR ("jobs\" + $KitJob + "\kit")
+$worker = Join-Path $kit 'igneum-worker-opencl.exe'
+$tele = Join-Path $kit 'igneum-gpu-telemetry.exe'
+$pack = Join-Path $kit 'pack-a'
+$deadline = (Get-Date).AddMinutes(2)
+while (-not ((Test-Path $worker) -and (Test-Path $tele)) -and (Get-Date) -lt $deadline) { Start-Sleep -Seconds 5 }
+if (-not (Test-Path $worker)) { "RESULT no worker at $worker"; exit 1 }
+$list = & $worker --list 2>&1
+$serve = Start-Process -FilePath $worker -ArgumentList '--serve','--pack',"`"$pack`"" -RedirectStandardInput $jobFile -NoNewWindow -PassThru
+exit 0
diff --git a/tools/ci/fixtures/kit-path-unchecked.ps1 b/tools/ci/fixtures/kit-path-unchecked.ps1
new file mode 100644
index 000000000..410235371
--- /dev/null
+++ b/tools/ci/fixtures/kit-path-unchecked.ps1
@@ -0,0 +1,14 @@
+# Fixture for tools/ci/kit-path-check.sh --self-test: the wiped-jobs-folder class (5 October 2026, 21:49Z: the 0.3.10
+# install cleared the jobs folder and the AMD kit job failed in seconds). Line 9 runs the worker before its check at
+# line 10; line 13 runs a literal jobs\ path that is never checked. Must fail twice. Never run; a stand-in for a job.
+$ErrorActionPreference = 'Continue'
+# 1. the worker is run first and tested after
+$jobs = Split-Path $env:IGNEUM_JOB_DIR
+$fetched = Join-Path $jobs 'fetch-race-worker-20261004'
+$exe = Join-Path $fetched 'igneum-worker-cuda.exe'
+& $exe --race 2>&1 | ForEach-Object { "RESULT $_" }
+if (-not (Test-Path $exe)) { Write-Output "RESULT race worker missing at $exe"; exit 2 }
+# 2. an inline literal under the jobs folder, never checked
+$KitJob = 'amd-kit-1'
+& "$env:IGNEUM_APP_DIR\jobs\$KitJob\kit\igneum-worker-opencl.exe" --list 2>&1
+exit 0
diff --git a/tools/ci/kit-path-check.sh b/tools/ci/kit-path-check.sh
new file mode 100755
index 000000000..693791f8e
--- /dev/null
+++ b/tools/ci/kit-path-check.sh
@@ -0,0 +1,110 @@
+#!/usr/bin/env bash
+# The wiped-jobs-folder class (5 October 2026, 21:49Z, bench-log 39f02ff): the app's install clears the jobs folder on
+# a PC, so a run job whose kit was fetched by an earlier fetch job finds nothing after an update and fails in seconds.
+# Rule: a run playbook that reaches a path under the app's jobs folder other than its own
+# (`$jobs = Split-Path $env:IGNEUM_JOB_DIR` then `Join-Path $jobs '<fetch id>'`, the race-5090.ps1 shape; or a literal
+# `jobs\<id>\...`, the amd-card-test.ps1 shape) tests that the kit is there (Test-Path, [IO.File]::Exists,
+# [IO.Directory]::Exists, Get-Item or Get-ChildItem with -ErrorAction) before its first use, and republishes the fetch
+# after any app update. A check on the kit's root or on anything under it covers the whole kit. This check reads every
+# *.ps1 under relay/playbooks/ and tools/ and fails on a kit path used before a presence check. The job's own folder
+# ($env:IGNEUM_JOB_DIR, made by the app for the run) is not a kit path.
+#
+# Usage: tools/ci/kit-path-check.sh                # the tree (tools/ci/fixtures/ left out)
+#        tools/ci/kit-path-check.sh <file.ps1>...   # named files (the jobs publisher runs it on the script it publishes)
+#        tools/ci/kit-path-check.sh --self-test     # must fire on the unchecked fixture and stay quiet on the correct one
+set -uo pipefail
+HERE="$(cd "$(dirname "$0")" && pwd)"
+REPO="$(cd "$HERE/../.." && pwd)"
+
+check_files() {
+  python3 - "$@" <<'PY'
+import re, sys
+
+SEED_LIT = re.compile(r'jobs\\')                                  # a literal path under the jobs folder
+SEED_FOLDER = re.compile(r'Split-Path\s+\$env:IGNEUM_JOB_DIR')     # the jobs folder itself: the parent of this job's folder
+CHECK = re.compile(r'Test-Path|\[IO\.(File|Directory)\]::Exists|Get-(Item|ChildItem)\b[^|]*-ErrorAction')
+ASSIGN = re.compile(r'^\s*\$([A-Za-z_][A-Za-z0-9_]*)\s*=(?!=)\s*(.*)$')
+# a right-hand side that only builds a path (the kit var it names is then a path, not a use of one)
+DERIV = re.compile(r'^(Join-Path\b|Split-Path\b|\(|"|\'|\[IO\.Path\]::Combine|\$env:|\$[A-Za-z_][A-Za-z0-9_]*\s*(\+|\.(TrimEnd|Replace)|$))')
+TEXT_ONLY = re.compile(r'^\s*(Write-Output|Write-Host|Write-Verbose|Say|Log)\b|^\s*"')
+VAR = re.compile(r'\$([A-Za-z_][A-Za-z0-9_]*)\b(?!:)')
+MSG = 'kit path used before a presence check: republish the fetch after any app update'
+
+rc = 0
+files = sys.argv[1:]
+with_kits = 0
+for path in files:
+    try:
+        lines = open(path, encoding='utf-8', errors='replace').read().split('\n')
+    except OSError as e:
+        print('FAIL %s: %s' % (path, e)); rc = 1; continue
+    folder = set()          # vars that are the jobs folder (always there)
+    root_of = {}            # kit var -> its root var
+    root_line = {}          # root var -> the line it is defined on
+    checked = set()         # roots with a presence check so far
+    reported = set()
+    inline_checked = False
+    fails = []
+    for ln, raw in enumerate(lines, 1):
+        s = raw.strip()
+        if not s or s.startswith('#'): continue
+        refs = set(VAR.findall(raw))
+        kit_refs = refs & set(root_of)
+        m = ASSIGN.match(raw)
+        if m:
+            name, rhs = m.group(1), m.group(2).strip()
+            if SEED_FOLDER.search(rhs) and not SEED_LIT.search(rhs):
+                folder.add(name); continue
+            deriv = bool(DERIV.match(rhs))
+            if deriv and (SEED_LIT.search(rhs) or (refs & folder)):
+                root_of[name] = name; root_line[name] = ln; continue
+            if deriv and kit_refs:
+                root_of[name] = root_of[sorted(kit_refs)[0]]; continue
+        if CHECK.search(raw):
+            for v in kit_refs: checked.add(root_of[v])
+            if SEED_LIT.search(raw): inline_checked = True
+            continue
+        for v in sorted(kit_refs):
+            r = root_of[v]
+            if r in checked or r in reported: continue
+            reported.add(r)
+            fails.append('FAIL %s:%d %s ($%s, kit path $%s defined at line %d)' % (path, ln, MSG, v, r, root_line[r]))
+        if SEED_LIT.search(raw) and not inline_checked and not TEXT_ONLY.match(raw):
+            inline_checked = True
+            fails.append('FAIL %s:%d %s (a literal jobs\\ path in a command, never checked)' % (path, ln, MSG))
+    if fails:
+        rc = 1
+        for f in fails: print(f)
+    elif root_of or inline_checked:
+        with_kits += 1
+        print('ok   %s (%d kit path%s, checked before use)' % (path, len(root_line), '' if len(root_line) == 1 else 's'))
+print('kit-path-check: %d files, %d with a fetched kit, %s' % (len(files), with_kits, 'all checked before use' if rc == 0 else 'FAILURES above'))
+sys.exit(rc)
+PY
+}
+
+if [ "${1:-}" = "--self-test" ]; then
+  F="$HERE/fixtures"
+  ok_out="$(check_files "$F/kit-path-ok.ps1" 2>&1)"; ok_rc=$?
+  bad_out="$(check_files "$F/kit-path-unchecked.ps1" 2>&1)"; bad_rc=$?
+  echo "self-test correct fixture: rc $ok_rc"; printf '%s\n' "$ok_out" | sed 's/^/  /'
+  echo "self-test unchecked fixture: rc $bad_rc"; printf '%s\n' "$bad_out" | sed 's/^/  /'
+  [ $ok_rc -eq 0 ] || { echo "SELF-TEST FAILED: the correct fixture was flagged"; exit 1; }
+  printf '%s\n' "$ok_out" | grep -q '^ok .*2 kit paths' || { echo "SELF-TEST FAILED: the correct fixture holds 2 kit paths, a different number was found"; exit 1; }
+  [ $bad_rc -ne 0 ] || { echo "SELF-TEST FAILED: the unchecked fixture passed"; exit 1; }
+  for want in 'kit-path-unchecked.ps1:9 ' 'kit-path-unchecked.ps1:13 '; do
+    printf '%s\n' "$bad_out" | grep -q "^FAIL .*$want.*republish the fetch after any app update" || { echo "SELF-TEST FAILED: the unchecked use at $want was not reported"; exit 1; }
+  done
+  [ "$(printf '%s\n' "$bad_out" | grep -c '^FAIL ')" -eq 2 ] || { echo "SELF-TEST FAILED: 2 failures expected"; exit 1; }
+  echo "self-test passed: the unchecked kit paths fail, the checked ones pass"
+  exit 0
+fi
+
+if [ $# -gt 0 ]; then
+  check_files "$@"; exit $?
+fi
+cd "$REPO"
+files=$(git ls-files 'relay/playbooks/**' 'tools/**' | grep -E '\.ps1$' | grep -v '^tools/ci/fixtures/' || true)
+if [ -z "$files" ]; then echo "kit-path-check: no .ps1 files under relay/playbooks/ or tools/"; exit 0; fi
+# shellcheck disable=SC2086
+check_files $files