diff --git a/.superpowers/sdd/evidence-task-7-report.md b/.superpowers/sdd/evidence-task-7-report.md
index 04f626b1..d2e2ab89 100644
--- a/.superpowers/sdd/evidence-task-7-report.md
+++ b/.superpowers/sdd/evidence-task-7-report.md
@@ -53,3 +53,12 @@ and absent validators fail closed. Acquisition accepts only the exact stored `So
 compares the response ETag with the stored discovery validator. The real smoke snapshots generation
 directory counts after every run and has an injected-failure cleanup mode; cleanup fails if Compose
 down fails or any owned container, volume, or network remains.
+
+The canonical smoke correction counts only root-level `corpus/gen-<32 hex>` directories. It exposed
+that the durable job path still published an empty unchanged generation; the pipeline now returns
+the existing ACTIVE generation without staging a directory when compatibility and all source
+fingerprints are unchanged. The smoke therefore proves directory deltas `+1`, `+0`, `+1`.
+Failure injection runs a real exit-97 command after resources exist and reaches the EXIT trap.
+Cleanup aggregates Compose-down, residual container/volume/network, and temp-directory failures
+while preserving the original failure status. S3 prefixes are validated before any client request
+for leading slash, UTF-8 byte length, controls, and DEL.
diff --git a/harness/tests/test_corpus_pipeline.py b/harness/tests/test_corpus_pipeline.py
index fa9e2357..511c6fc0 100644
--- a/harness/tests/test_corpus_pipeline.py
+++ b/harness/tests/test_corpus_pipeline.py
@@ -431,6 +431,20 @@ def test_unchanged_documents_skip_acquire_normalize_chunk_and_embed(tmp_path):
     assert second_embedder.calls == []
 
 
+def test_unchanged_job_reuses_active_generation_without_new_directory(tmp_path):
+    source = Source([(item("one", "a"), "hello")])
+    candidate = pipeline(tmp_path, source)
+    args = dict(workspace_id="demo", workspace_root=tmp_path,
+                config_fingerprint="sha256:" + "1" * 64,
+                input_fingerprint="sha256:" + "2" * 64)
+    first = candidate.run_as_job(**args)
+    count = len(candidate.store.list_generations())
+    second = candidate.run_as_job(**args)
+    assert second.generation == first.generation
+    assert second.published is False
+    assert len(candidate.store.list_generations()) == count
+
+
 def test_removed_documents_are_marked_and_absent_from_new_manifest(tmp_path):
     one, two = item("one", "a"), item("two", "b")
     pipeline(tmp_path, Source([(one, "one"), (two, "two")])).run()
diff --git a/harness/tests/test_s3_evidence_source.py b/harness/tests/test_s3_evidence_source.py
index b23d7578..710b44fc 100644
--- a/harness/tests/test_s3_evidence_source.py
+++ b/harness/tests/test_s3_evidence_source.py
@@ -104,6 +104,15 @@ def test_s3_rejects_leading_slash_prefix_empty_and_control_keys():
             list(S3EvidenceSource(bucket="evidence", prefix="clinical/", client=client).discover())
 
 
+@pytest.mark.parametrize("prefix", ["/bad", "x" * 1025, "bad\x00prefix", "bad\x7fprefix"])
+def test_s3_rejects_invalid_prefix_before_client_request(prefix):
+    from tht.adapters.evidence.s3 import S3EvidenceSource
+    client = Client()
+    with pytest.raises(ValueError, match="prefix"):
+        S3EvidenceSource(bucket="evidence", prefix=prefix, client=client)
+    assert client.list_calls == 0
+
+
 def test_s3_hard_page_limit_never_requests_page_max_plus_one():
     from tht.adapters.evidence.s3 import S3EvidenceSource
     client = Client()
diff --git a/harness/tht/adapters/evidence/s3.py b/harness/tht/adapters/evidence/s3.py
index 8e9ef4d5..e0a45fb7 100644
--- a/harness/tht/adapters/evidence/s3.py
+++ b/harness/tht/adapters/evidence/s3.py
@@ -29,8 +29,9 @@ class S3EvidenceSource:
         if (not bucket_valid or bucket_is_ip
                 or any(value < 1 for value in (max_bytes, max_objects, max_pages, page_size))):
             raise ValueError("S3 evidence limits and bucket must be non-empty and positive")
-        if prefix.startswith("/"):
-            raise ValueError("S3 prefix must not start with a slash")
+        if (prefix.startswith("/") or len(prefix.encode()) > 1024
+                or any(ord(char) < 32 or ord(char) == 127 for char in prefix)):
+            raise ValueError("S3 prefix is invalid")
         if endpoint_url:
             parsed = urlsplit(endpoint_url)
             if parsed.username or parsed.password:
diff --git a/harness/tht/corpus/pipeline.py b/harness/tht/corpus/pipeline.py
index c5a66649..2b860ff7 100644
--- a/harness/tht/corpus/pipeline.py
+++ b/harness/tht/corpus/pipeline.py
@@ -220,6 +220,16 @@ class CorpusPipeline:
             "dimensions": self.embedding_dimensions,
             "chunk_policy": asdict(self.chunk_policy),
         })
+        previous = self.store.active_manifest()
+        if (not dry_run and resume_run_id is None and previous is not None
+                and previous.metadata.get("compatibility_fingerprint") == compatibility
+                and previous.metadata.get("fingerprints") == {
+                    item.source_id: item.fingerprint for _, item in discovered
+                }):
+            return PipelineResult(
+                "succeeded", previous.manifest_id, False, (),
+                tuple(sorted(item.source_id for _, item in discovered)), (), previous,
+            )
         spec = JobSpec(
             workspace_id=workspace_id,
             job_type="evidence",
diff --git a/scripts/preprocess-smoke.sh b/scripts/preprocess-smoke.sh
index 5377a0da..ca58403a 100755
--- a/scripts/preprocess-smoke.sh
+++ b/scripts/preprocess-smoke.sh
@@ -2,20 +2,50 @@
 set -eu
 cd "$(dirname "$0")/.."
 
-tmp=$(mktemp -d "${TMPDIR:-/tmp}/thoth-preprocess.XXXXXX")
-project="thoth-preprocess-$$"
+if [ "${1:-}" = "--cleanup-failure" ] && [ -z "${PREPROCESS_SMOKE_CHILD:-}" ]; then
+  child_project="thoth-preprocess-failure-$$"
+  child_tmp=$(mktemp -d "${TMPDIR:-/tmp}/thoth-preprocess-failure.XXXXXX")
+  set +e
+  PREPROCESS_SMOKE_CHILD=1 PREPROCESS_SMOKE_INJECT_FAILURE=1 \
+    PREPROCESS_SMOKE_PROJECT="$child_project" PREPROCESS_SMOKE_TMP="$child_tmp" "$0"
+  child_status=$?
+  set -e
+  test "$child_status" -eq 97
+  test ! -e "$child_tmp"
+  test -z "$(docker ps -aq --filter "label=com.docker.compose.project=$child_project")"
+  test -z "$(docker volume ls -q --filter "label=com.docker.compose.project=$child_project")"
+  test -z "$(docker network ls -q --filter "label=com.docker.compose.project=$child_project")"
+  echo "injected preprocessing failure preserved status and cleaned every owned resource."
+  exit 0
+fi
+
+tmp=${PREPROCESS_SMOKE_TMP:-$(mktemp -d "${TMPDIR:-/tmp}/thoth-preprocess.XXXXXX")}
+project=${PREPROCESS_SMOKE_PROJECT:-thoth-preprocess-$$}
 compose=""
 cleanup() {
-  trap - EXIT HUP INT TERM
+  original_status=$?
+  cleanup_failed=0
+  set +e
   if [ -n "$compose" ]; then
     $compose down --volumes >/dev/null
+    test "$?" -eq 0 || cleanup_failed=1
   fi
-  test -z "$(docker ps -aq --filter "label=com.docker.compose.project=$project")"
-  test -z "$(docker volume ls -q --filter "label=com.docker.compose.project=$project")"
-  test -z "$(docker network ls -q --filter "label=com.docker.compose.project=$project")"
+  test -z "$(docker ps -aq --filter "label=com.docker.compose.project=$project")" || cleanup_failed=1
+  test -z "$(docker volume ls -q --filter "label=com.docker.compose.project=$project")" || cleanup_failed=1
+  test -z "$(docker network ls -q --filter "label=com.docker.compose.project=$project")" || cleanup_failed=1
   rm -rf "$tmp"
+  test ! -e "$tmp" || cleanup_failed=1
+  if [ "$original_status" -ne 0 ]; then
+    exit "$original_status"
+  fi
+  if [ "$cleanup_failed" -ne 0 ]; then
+    exit 1
+  fi
 }
-trap cleanup EXIT HUP INT TERM
+trap cleanup EXIT
+trap 'exit 129' HUP
+trap 'exit 130' INT
+trap 'exit 143' TERM
 mkdir -p "$tmp/source/evidence"
 printf '%s\n' '# Evidence' 'generation one' >"$tmp/source/evidence/a.md"
 for name in bootstrap migrator reader writer; do
@@ -61,15 +91,12 @@ $compose build preprocess-evidence
 $compose up -d vector-db mock-embeddings
 $compose run --rm vector-reconcile >/dev/null
 $compose run --rm --no-deps vector-migrate >/dev/null
-if [ "${1:-}" = "--cleanup-failure" ]; then
-  cleanup
-  test ! -e "$tmp"
-  echo "injected preprocessing failure cleanup passed."
-  exit 0
+if [ "${PREPROCESS_SMOKE_INJECT_FAILURE:-0}" = "1" ]; then
+  sh -c 'exit 97'
 fi
 generation_count() {
-  $compose run --rm --no-deps --entrypoint sh preprocess-evidence -c \
-    'find /data/workspaces/preprocess-evidence/corpus/generations -mindepth 1 -maxdepth 1 -type d 2>/dev/null | wc -l'
+  $compose run --rm --no-deps --entrypoint /opt/venv/bin/python preprocess-evidence -c \
+    'import pathlib,re; root=pathlib.Path("/data/workspaces/preprocess-evidence/corpus"); print(sum(1 for p in root.iterdir() if p.is_dir() and re.fullmatch(r"gen-[0-9a-f]{32}",p.name)) if root.exists() else 0)'
 }
 before=$(generation_count)
 first=$($compose run --rm preprocess-evidence)
@@ -103,5 +130,3 @@ import json, sys
 assert json.loads(sys.argv[1])["generation"] == sys.argv[2].strip()
 PY
 echo "real Compose preprocessing unchanged rerun, mutation, DWH job, and ACTIVE publish passed."
-cleanup
-test ! -e "$tmp"