diff --git a/.github/workflows/gitnexus-skill-evolution.yml b/.github/workflows/gitnexus-skill-evolution.yml
index c004bb515..8d02917c1 100644
--- a/.github/workflows/gitnexus-skill-evolution.yml
+++ b/.github/workflows/gitnexus-skill-evolution.yml
@@ -63,13 +63,14 @@
 #     uploads, and a promotion (if any) opens a well-formed PR. Run
 #     29907431284 (2026-07-22) went green end to end in 14h45m and reached a
 #     gate decision (`insufficient_evidence`, no promotion).
-# [ ] After resizing the runner, prove a manual workers=3 run has zero excluded
-#     runs and does not stretch the 48-minute serial mean toward the session
-#     ceiling; then set GITNEXUS_EVOLUTION_WORKERS=3 and
+# [ ] Confirm a workers=3 dispatch has zero excluded runs (review sessions in
+#     33962002890 averaged ~19m serial, well under the 90m session ceiling).
+#     Then set GITNEXUS_EVOLUTION_WORKERS=3 and
 #     GITNEXUS_EVOLUTION_ENABLED=true for scheduled runs. Scheduled runs
-#     require both values, so leaving workers unset/1 is an immediate rollback;
-#     workflow_dispatch remains available for the proof and bills real API
-#     usage on GITNEXUS_BENCH_ANTHROPIC_API_KEY or GITNEXUS_BENCH_OPENAI_API_KEY.
+#     require both values, so leaving the var unset is an immediate rollback.
+#     Dispatch defaults to 3; pass workers=1 only to debug a contended host.
+#     Weekly generations reuse matching incumbent/CE cells from the previous
+#     artifact so the paid matrix is the new candidate, not a 54-cell replay.
 name: GitNexus skill evolution
 
 on:
@@ -92,9 +93,9 @@ on:
         default: '3'
         type: string
       workers:
-        description: 'Benchmark cells of one task to run at once — raise only to match the runner’s vCPUs'
+        description: 'Benchmark cells of one task to run at once — 3 fits the evolution box; drop to 1 only if siblings hit the session ceiling'
         required: false
-        default: '1'
+        default: '3'
         type: string
       model:
         description: 'Model for the benchmark arms (match the model your skill users run)'
@@ -172,6 +173,12 @@ jobs:
     # stops the runner just disappears mid-step. Scheduled runs can start well
     # after the cron (the 2026-08-01 run was queued 65min late), so the job
     # budget has to absorb that delay and still land inside the uptime window.
+    # A Friday workflow_dispatch on a box that already booted for Saturday's
+    # cron inherits leftover uptime, not a fresh 24h. Run 33962002890 started
+    # Friday 10:57 UTC and vanished at the Saturday 03:00 stop — 51 finished
+    # sessions never uploaded. run-evolution.sh therefore passes
+    # --max-runtime-seconds from /proc/uptime so the sweep fails in-process
+    # and this always() upload still runs.
     timeout-minutes: 1260
     permissions:
       contents: read # The promotion PR uses a short-lived App token minted below.
diff --git a/eval/tests/test_comparator_reuse.py b/eval/tests/test_comparator_reuse.py
new file mode 100644
index 000000000..bcb8a7b3d
--- /dev/null
+++ b/eval/tests/test_comparator_reuse.py
@@ -0,0 +1,177 @@
+"""Comparator-row reuse: skip unchanged incumbent/CE cells, never candidates."""
+
+from __future__ import annotations
+
+import hashlib
+from datetime import UTC, datetime, timedelta
+from pathlib import Path
+
+import pytest
+
+from workflow_bench.comparator_reuse import (
+    ComparatorReuseExpectation,
+    TaskReuseBinding,
+    materialize_reused_row,
+    row_is_reusable_comparator,
+    select_reusable_comparator_rows,
+)
+from workflow_bench.proposer_sandbox import SandboxError
+from workflow_bench.runner_sessions import PARENT_EVENT_STREAM_SOURCE
+
+
+def _digest(text: str = "blob") -> str:
+    return hashlib.sha256(text.encode()).hexdigest()
+
+
+def _artifact(name: str = "session-1.jsonl", payload: bytes = b'{"type":"ok"}\n') -> dict:
+    return {
+        "path": f"transcripts/{name}",
+        "sha256": hashlib.sha256(payload).hexdigest(),
+        "bytes": len(payload),
+        "source": PARENT_EVENT_STREAM_SOURCE,
+    }
+
+
+def _row(**overrides) -> dict:
+    base = {
+        "task": "review-pr-2718-defect",
+        "arm": "review",
+        "run": 0,
+        "ok": True,
+        "error_kind": None,
+        "model": "gpt-5.6-sol",
+        "benchmark_model": "gpt-5.6-sol",
+        "effort": "xhigh",
+        "sandbox_backend": "bwrap",
+        "task_base_sha": "a" * 40,
+        "task_prompt_digest": _digest("prompt"),
+        "oracle_digest": _digest("oracle"),
+        "oracle_command_digest": _digest("oracle-cmd"),
+        "oracle_manifest_digest": _digest("oracle-man"),
+        "skill_digest": _digest("skill"),
+        "candidate_overlay_digest": None,
+        "review_evidence_valid": True,
+        "review_score": {"weighted_f1": 0.4},
+        "review_weighted_f1": 0.4,
+        "transcript_missing": False,
+        "transcript_artifacts": [_artifact()],
+        "recorded_at": datetime.now(UTC).isoformat(),
+    }
+    base.update(overrides)
+    return base
+
+
+def _expected(**overrides) -> ComparatorReuseExpectation:
+    now = datetime.now(UTC)
+    values = dict(
+        model="gpt-5.6-sol",
+        effort="xhigh",
+        sandbox_backend="bwrap",
+        runtime_digest=None,
+        now=now,
+        max_age=timedelta(days=90),
+        tasks={
+            "review-pr-2718-defect": TaskReuseBinding(
+                task_base_sha="a" * 40,
+                task_prompt_digest=_digest("prompt"),
+                oracle_digest=_digest("oracle"),
+                oracle_command_digest=_digest("oracle-cmd"),
+                oracle_manifest_digest=_digest("oracle-man"),
+            )
+        },
+        skill_digests={"review": _digest("skill"), "ce_review": None},
+        ce_plugin_version="3.24.0",
+        ce_plugin_manifest_digest=_digest("ce"),
+    )
+    values.update(overrides)
+    return ComparatorReuseExpectation(**values)
+
+
+def test_matching_incumbent_review_row_is_reusable() -> None:
+    assert row_is_reusable_comparator(_row(), _expected()) is True
+
+
+def test_candidate_rows_are_never_reusable() -> None:
+    assert row_is_reusable_comparator(_row(arm="candidate_review"), _expected()) is False
+
+
+def test_skill_digest_drift_rejects_reuse() -> None:
+    assert row_is_reusable_comparator(_row(), _expected(skill_digests={"review": _digest("other")})) is False
+
+
+def test_excluded_or_failed_rows_are_not_reusable() -> None:
+    expected = _expected()
+    assert row_is_reusable_comparator(_row(error_kind="session-error", ok=False), expected) is False
+    assert row_is_reusable_comparator(_row(ok=False), expected) is False
+    assert row_is_reusable_comparator(_row(review_evidence_valid=False), expected) is False
+    assert row_is_reusable_comparator(_row(recorded_at=(datetime.now(UTC) - timedelta(days=91)).isoformat()), expected) is False
+
+
+def test_runtime_digest_mismatch_rejects_when_both_sides_are_bound() -> None:
+    row = _row(runtime_digest=_digest("old-cli"))
+    assert row_is_reusable_comparator(row, _expected(runtime_digest=_digest("new-cli"))) is False
+    assert row_is_reusable_comparator(row, _expected(runtime_digest=_digest("old-cli"))) is True
+    assert row_is_reusable_comparator(_row(), _expected(runtime_digest=_digest("new-cli"))) is True
+
+
+def test_ce_review_matches_plugin_digest_not_repo_skill() -> None:
+    row = _row(
+        arm="ce_review",
+        skill_digest=None,
+        ce_plugin_version="3.24.0",
+        ce_plugin_manifest_digest=_digest("ce"),
+    )
+    assert row_is_reusable_comparator(row, _expected()) is True
+    assert (
+        row_is_reusable_comparator(row, _expected(ce_plugin_manifest_digest=_digest("other")))
+        is False
+    )
+
+
+def test_select_drops_conflicting_duplicates() -> None:
+    first = _row(review_weighted_f1=0.4)
+    second = _row(review_weighted_f1=0.9, recorded_at=datetime.now(UTC).isoformat())
+    selected = select_reusable_comparator_rows([first, second], expected=_expected())
+    assert selected == {}
+    same = select_reusable_comparator_rows([first, dict(first)], expected=_expected())
+    assert ("review-pr-2718-defect", "review", 0) in same
+
+
+def test_materialize_copies_transcript_and_review_artifacts(tmp_path: Path) -> None:
+    payload = b'{"type":"result"}\n'
+    source = tmp_path / "prior"
+    dest = tmp_path / "fresh"
+    (source / "transcripts").mkdir(parents=True)
+    dest.mkdir()
+    transcript = source / "transcripts" / "session-1.jsonl"
+    transcript.write_bytes(payload)
+    transcript.chmod(0o600)
+    review = source / "review-pr-2718-defect-review-run0.review.json"
+    review.write_text('{"verdict":"comment"}\n')
+    patch = source / "review-pr-2718-defect-review-run0.patch"
+    patch.write_text("diff\n")
+    row = _row(
+        review_artifact=review.name,
+        transcript_artifacts=[_artifact(payload=payload)],
+    )
+
+    copied = materialize_reused_row(row, source_dir=source, dest_dir=dest)
+
+    assert copied["reused"] is True
+    assert copied["reused_from_recorded_at"] == row["recorded_at"]
+    assert (dest / "transcripts" / "session-1.jsonl").read_bytes() == payload
+    assert (dest / review.name).read_text() == review.read_text()
+    assert (dest / patch.name).read_text() == "diff\n"
+    assert copied["transcript_artifacts"][0]["sha256"] == hashlib.sha256(payload).hexdigest()
+
+
+def test_materialize_rejects_same_directory_and_missing_transcript(tmp_path: Path) -> None:
+    source = tmp_path / "prior"
+    source.mkdir()
+    row = _row()
+    with pytest.raises(SandboxError, match="same results directory"):
+        materialize_reused_row(row, source_dir=source, dest_dir=source)
+    dest = tmp_path / "fresh"
+    dest.mkdir()
+    with pytest.raises(SandboxError, match="missing"):
+        materialize_reused_row(row, source_dir=source, dest_dir=dest)
diff --git a/eval/tests/test_evolve.py b/eval/tests/test_evolve.py
index c135584de..bf790d1b6 100644
--- a/eval/tests/test_evolve.py
+++ b/eval/tests/test_evolve.py
@@ -15,13 +15,18 @@ import pytest
 from workflow_bench import evolve, evolution
 from workflow_bench.runner_sessions import PARENT_EVENT_STREAM_SOURCE
 from workflow_bench.evolve import (
+    MIN_INSTANCE_SWEEP_SECONDS,
     build_parser,
     build_proposer_prompt,
+    capped_timeout_seconds,
     executed_benchmark_arms,
     generation_timeout_seconds,
+    instance_window_budget_from_proc,
+    instance_window_budget_seconds,
     load_jsonl,
     proposer_evidence_entries,
     read_learnings,
+    remaining_runtime_seconds,
     resolve_incumbent_arms,
     runner_argv,
     select_evidence,
@@ -922,6 +927,27 @@ def test_runner_argv_inserts_ce_review_for_review_overlay(tmp_path):
     )
     arms = argv[argv.index("--arms") + 1 : argv.index("--promotion-metric")]
     assert arms == ["ce_review", "review", "candidate_review"]
+    assert "--reuse-results" not in argv
+
+
+def test_runner_argv_forwards_prior_results_for_comparator_reuse(tmp_path):
+    args = build_parser().parse_args(
+        ["--tasks", "t.yaml", "--model", "pinned", "--arms", "review"]
+    )
+    overlay = tmp_path / "overlay"
+    skill = overlay / ".claude" / "skills" / "gitnexus-review" / "SKILL.md"
+    skill.parent.mkdir(parents=True)
+    skill.write_text("candidate")
+    prior = tmp_path / "prior-bench"
+    argv = runner_argv(
+        args,
+        tmp_path / "bench",
+        overlay,
+        task_bindings=[{"id": "task"}],
+        target_base_digests={},
+        reuse_results=prior,
+    )
+    assert argv[argv.index("--reuse-results") + 1] == str(prior)
 
 
 def test_runner_argv_omits_proposer_for_manual_overlay(tmp_path):
@@ -1118,6 +1144,52 @@ def test_generation_timeout_rejects_unknown_arm() -> None:
         )
 
 
+def test_instance_window_budget_leaves_upload_reserve() -> None:
+    # Friday 10:57 on a box that booted 02:45 Saturday-window: ~8.2h uptime.
+    leftover = instance_window_budget_seconds(8.2 * 3600)
+    assert leftover == int(86_400 - 8.2 * 3600 - 5_400)
+    assert leftover >= MIN_INSTANCE_SWEEP_SECONDS
+    with pytest.raises(ValueError, match="only .*s left"):
+        instance_window_budget_seconds(23.5 * 3600)
+    with pytest.raises(ValueError, match="uptime must be"):
+        instance_window_budget_seconds(float("nan"))
+
+
+def test_instance_window_budget_from_proc_reads_uptime_and_env(
+    tmp_path: Path, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    uptime = tmp_path / "uptime"
+    uptime.write_text("3600.00 8000.00\n")
+    monkeypatch.setenv("EVENTBRIDGE_INSTANCE_WINDOW_SECONDS", "20000")
+    monkeypatch.setenv("EVENTBRIDGE_STOP_RESERVE_SECONDS", "1000")
+    assert instance_window_budget_from_proc(uptime) == 20000 - 3600 - 1000
+    with pytest.raises(ValueError, match="cannot read instance uptime"):
+        instance_window_budget_from_proc(tmp_path / "missing")
+
+
+def test_capped_timeout_clamps_to_leftover_window() -> None:
+    assert capped_timeout_seconds(10_000, None) == 10_000
+    assert capped_timeout_seconds(10_000, 90) == 90
+    with pytest.raises(ValueError, match="no time remains"):
+        capped_timeout_seconds(10_000, 0)
+    started = time.monotonic() - 40
+    assert remaining_runtime_seconds(max_runtime_seconds=None, started_monotonic=started) is None
+    leftover = remaining_runtime_seconds(max_runtime_seconds=100, started_monotonic=started)
+    assert leftover is not None
+    assert 50 <= leftover <= 60
+
+
+def test_parser_rejects_non_positive_max_runtime() -> None:
+    with pytest.raises(SystemExit):
+        build_parser().parse_args(
+            ["--tasks", "t.yaml", "--model", "pinned", "--max-runtime-seconds", "0"]
+        )
+    args = build_parser().parse_args(
+        ["--tasks", "t.yaml", "--model", "pinned", "--max-runtime-seconds", "7200"]
+    )
+    assert args.max_runtime_seconds == 7200
+
+
 @pytest.mark.skipif(sys.platform != "linux", reason="Bubblewrap PID namespaces require Linux")
 def test_outer_runner_pid_namespace_kills_setsid_descendant(tmp_path):
     try:
diff --git a/eval/tests/test_review_corpus.py b/eval/tests/test_review_corpus.py
index 42f18cb7c..cbaa2695e 100644
--- a/eval/tests/test_review_corpus.py
+++ b/eval/tests/test_review_corpus.py
@@ -32,6 +32,10 @@ def test_review_corpus_is_immutable_and_task_bound():
         assert task["ref"] == case["base_sha"]
         assert task["sandbox_copy"] == [f"eval/workflow_bench/review_cases/{patch.name}"]
         assert task["setup"] == review_case_setup_command(patch.name)
+        assert any(
+            dep.get("source") == "gitnexus-shared/dist" and dep.get("target") == "gitnexus-shared/dist"
+            for dep in task["sandbox_dependencies"]
+        )
 
 
 def test_hidden_labels_are_not_recoverable_from_visible_task_input():
diff --git a/eval/tests/test_sanitized_graph.py b/eval/tests/test_sanitized_graph.py
index 7b5dfc093..d7f73d756 100644
--- a/eval/tests/test_sanitized_graph.py
+++ b/eval/tests/test_sanitized_graph.py
@@ -212,6 +212,22 @@ def test_prepare_sanitized_graph_builds_once_from_parentless_tree_and_caches_onl
     assert removed == [seed]
 
 
+def test_prepare_sanitized_graph_requires_head_when_given_a_template(tmp_path: Path):
+    with pytest.raises(SandboxError, match="sanitized HEAD"):
+        sanitized_graph.prepare_sanitized_graph(
+            {},
+            repo=tmp_path,
+            resolved_sha="b" * 40,
+            parent=tmp_path,
+            cache=SimpleNamespace(),  # type: ignore[arg-type]
+            claude_bin="claude",
+            bwrap_bin="bwrap",
+            runtime_mounts=(),
+            clone_template=tmp_path,
+            sanitized_head=None,
+        )
+
+
 def test_graph_snapshot_rejects_arm_sanitization_identity_drift(tmp_path: Path):
     assets = SimpleNamespace(
         digest="digest",
diff --git a/eval/tests/test_session_progress.py b/eval/tests/test_session_progress.py
index 9e59ba4bf..416c6206c 100644
--- a/eval/tests/test_session_progress.py
+++ b/eval/tests/test_session_progress.py
@@ -11,7 +11,7 @@ import io
 import json
 import time
 
-from workflow_bench.runner_sessions import SessionProgress
+from workflow_bench.runner_sessions import SessionProgress, neutralize_ci_log_text
 
 
 def _drain_lines(stream: io.StringIO) -> list[str]:
@@ -325,3 +325,48 @@ def test_cell_failure_detail_line_bounds_a_huge_detail() -> None:
     assert line is not None
     assert "truncated" in line
     assert len(line) < MAX_CELL_DETAIL_CHARS + 200
+
+
+def test_progress_neutralizes_github_actions_annotation_forms() -> None:
+    rewritten = neutralize_ci_log_text(
+        "gitnexus/src/cli/optional-grammars.ts(18,36): error TS2307: Cannot find module "
+        "'gitnexus-shared'\n::error::Composite projects may not disable incremental compilation.\n"
+        "##[error]tsc failed"
+    )
+    assert "): error TS2307" not in rewritten
+    assert "): compiler-error TS2307" in rewritten
+    assert "::error::" not in rewritten
+    assert "[:]error::" in rewritten
+    assert "##[error]" not in rewritten
+    assert "# [error]tsc failed" in rewritten
+
+    stream = io.StringIO()
+    progress = SessionProgress("review-pr-2718-defect-ce_review-run0", stream=stream, heartbeat_s=3600)
+    events = [
+        {
+            "type": "assistant",
+            "message": {
+                "content": [{"type": "tool_use", "id": "b1", "name": "Bash", "input": {"command": "npx tsc --noEmit"}}]
+            },
+        },
+        {
+            "type": "user",
+            "message": {
+                "content": [
+                    {
+                        "type": "tool_result",
+                        "tool_use_id": "b1",
+                        "is_error": True,
+                        "content": "gitnexus/src/cli/optional-grammars.ts(18,36): error TS2307: Cannot find module 'gitnexus-shared'",
+                    }
+                ]
+            },
+        },
+    ]
+    for event in events:
+        _observe(progress, (json.dumps(event) + "\n").encode())
+
+    output = stream.getvalue()
+    assert "): error TS2307" not in output
+    assert "): compiler-error TS2307" in output
+    assert "result=error" in output
diff --git a/eval/tests/test_workflow_bench.py b/eval/tests/test_workflow_bench.py
index 45d0b2f35..889cdee78 100644
--- a/eval/tests/test_workflow_bench.py
+++ b/eval/tests/test_workflow_bench.py
@@ -245,6 +245,9 @@ def test_shipped_scenarios_opt_out_the_cross_module_cell_and_rebuild_graph_asset
     assert skipped == ["cross-module-parse-retry"]
     assert all(not task.get("sandbox_copy") for task in tasks)
     assert all(task["sandbox_dependencies"] for task in tasks)
+    assert all(
+        any(dep.get("source") == "gitnexus-shared/dist" for dep in task["sandbox_dependencies"]) for task in tasks
+    )
     assert all(task["oracle"]["command"] and task["oracle"]["files"] for task in tasks)
     assert all("./node_modules/.bin/vitest run" in task["oracle"]["command"] for task in tasks)
     assert all("npx vitest" not in task["oracle"]["command"] for task in tasks)
diff --git a/eval/tests/test_workflow_bench_sessions.py b/eval/tests/test_workflow_bench_sessions.py
index 1f66f071f..9a7eb4e87 100644
--- a/eval/tests/test_workflow_bench_sessions.py
+++ b/eval/tests/test_workflow_bench_sessions.py
@@ -1348,3 +1348,26 @@ def test_make_worktree_clone_has_no_tags_but_keeps_all_branches(tmp_path):
 
     current = _git(target, "rev-parse", "HEAD").stdout.strip()
     assert current == other_sha
+
+
+def test_copy_isolated_tree_does_not_share_git_objects_or_refs(tmp_path):
+    repo = tmp_path / "repo"
+    repo.mkdir()
+    _git(repo, "init", "--quiet")
+    _git(repo, "checkout", "--quiet", "-b", "main")
+    sha = _git_commit(repo, "base")
+    clones = tmp_path / "clones"
+    clones.mkdir()
+    template = runner.make_worktree(repo, sha, clones)
+    (template / "marker.txt").write_text("template\n")
+
+    copy = runner.copy_isolated_tree(template, clones)
+    assert copy != template
+    assert (copy / "marker.txt").read_text() == "template\n"
+    (copy / "marker.txt").write_text("copy\n")
+    assert (template / "marker.txt").read_text() == "template\n"
+    copy_head = _git(copy, "rev-parse", "HEAD").stdout.strip()
+    template_head = _git(template, "rev-parse", "HEAD").stdout.strip()
+    assert copy_head == template_head == sha
+    alternates = copy / ".git" / "objects" / "info" / "alternates"
+    assert not alternates.exists()
diff --git a/eval/workflow_bench/README.md b/eval/workflow_bench/README.md
index 79bd4bfea..0b722d340 100644
--- a/eval/workflow_bench/README.md
+++ b/eval/workflow_bench/README.md
@@ -168,6 +168,34 @@ router thresholds as an incumbent policy, not permanent truth. Candidate
 changes run offline in the same throwaway clones as the incumbent; production
 skills never rewrite themselves from a live task.
 
+On the self-hosted evolution box, `run-evolution.sh` caps the sweep with
+`--max-runtime-seconds` derived from `/proc/uptime` (24h EventBridge window
+minus a 90-minute upload reserve). A `workflow_dispatch` that lands on an
+already-running instance therefore exits in-process instead of vanishing when
+the box stops — a cancelled GitHub job skips even `if: always()`, which is
+how run 33962002890 lost 51 finished sessions. Local runs are uncapped.
+
+A review generation is 6 tasks × 3 arms × 3 runs. Serial workers=1 at ~19
+minutes per session is a 16-hour job (run 33962002890). Two harness changes
+cut that without shrinking the gate:
+
+- **Comparator reuse.** `evolve.py` forwards the seed / prior generation as
+  `--reuse-results`. Incumbent `review` and `ce_review` rows are copied into
+  the new `results.jsonl` when model, effort, task SHA, prompt digest, oracle
+  bytes, incumbent skill digest, CE plugin digest, and sandbox backend still
+  match. Candidate arms always run. A weekly generation with an unchanged
+  incumbent therefore pays 18 sessions, not 54. A promotion, model change,
+  task-corpus change, or harness `RUNTIME_DIGEST` change invalidates the
+  lock and re-runs the comparators.
+- **Sanitized clone templates.** Each unique task SHA is cloned and
+  sanitized once. Cells copy that parentless snapshot (reflink when the
+  filesystem allows) instead of `git clone --no-local` plus repack/prune/fsck
+  54 times. Isolation is a private `.git`, not a second copy of full history.
+
+Dispatch defaults to `--workers 3` so those 18 paid cells can overlap. Size
+workers to the host: a cell that loses CPU and hits the session ceiling is
+an excluded run the gate refuses.
+
 Build an overlay that mirrors only the canonical repo-local skill paths:
 
 ```text
@@ -368,10 +396,10 @@ paired benchmark as any other candidate.
 
 For ad-hoc use, run the driver on the existing re-evaluation triggers
 (model/harness change or 90-day staleness). The repository workflow runs a
-deliberate weekly drift check: scheduled concurrency stays serial unless
-`GITNEXUS_EVOLUTION_WORKERS` is raised after a funded host-sized proof, and
-`--workers` is bounded to 1–8 before paid work starts. `--generations` remains
-the only loop bound.
+deliberate weekly drift check: dispatch defaults to three concurrent cells
+of one task; scheduled concurrency still requires
+`GITNEXUS_EVOLUTION_WORKERS=3` after a clean proof. `--workers` is bounded
+to 1–8 before paid work starts. `--generations` remains the only loop bound.
 
 ## Free-model setup (no paid tokens)
 
diff --git a/eval/workflow_bench/comparator_reuse.py b/eval/workflow_bench/comparator_reuse.py
new file mode 100644
index 000000000..96a0f9a4a
--- /dev/null
+++ b/eval/workflow_bench/comparator_reuse.py
@@ -0,0 +1,387 @@
+"""Reuse frozen comparator cells when the current sweep is still the same experiment.
+
+Weekly skill evolution re-runs incumbent ``review`` / ``ce_review`` (and the
+implementation incumbents) even when the model, effort, tasks, oracles,
+incumbent skill bytes, and CE plugin have not changed. Those arms are the
+baseline the gate compares a *new* candidate against — they are not the
+thing being evolved. Replaying them burns two-thirds of a generation.
+
+This module selects prior ``results.jsonl`` rows that are safe to carry
+forward. Candidate arms are never reused. A mismatch on any bound field
+falls through to a paid cell. Missing artifacts also fall through: a reused
+row that the proposer cannot read is worse than spending the tokens again.
+"""
+
+from __future__ import annotations
+
+import hashlib
+import json
+import os
+import re
+import stat
+from collections.abc import Mapping, Sequence
+from dataclasses import dataclass
+from datetime import UTC, datetime, timedelta
+from pathlib import Path, PurePosixPath
+from typing import Any
+
+from .evolution import CANDIDATE_ARMS, EVIDENCE_MAX_AGE_DAYS
+from .proposer_sandbox import SandboxError
+from .runner_sessions import MAX_TRANSCRIPT_BYTES, PARENT_EVENT_STREAM_SOURCE
+from .runtime_mounts import CE_ARMS
+
+REUSABLE_COMPARATOR_ARMS = frozenset(
+    {
+        "review",
+        "ce_review",
+        "workflow",
+        "workflow_direct",
+        "ce_workflow",
+        "ce_workflow_direct",
+        "baseline",
+        "baseline_nomcp",
+    }
+)
+# Must stay aligned with runner.EXCLUDED_ERROR_KINDS plus review-invalid.
+# A reused row becomes promotion evidence; excluded kinds cannot enter that set.
+REUSE_EXCLUDED_ERROR_KINDS = frozenset(
+    {
+        "session-error",
+        "infra-error",
+        "evidence-unverified",
+        "cleanup-failure",
+        "review-evidence-invalid",
+        "cancelled",
+    }
+)
+_TRANSCRIPT_NAME = re.compile(r"[A-Za-z0-9._-]{1,200}")
+CellKey = tuple[str, str, int]
+
+
+@dataclass(frozen=True)
+class TaskReuseBinding:
+    """Per-task identity the prior row must still match."""
+
+    task_base_sha: str
+    task_prompt_digest: str
+    oracle_digest: str
+    oracle_command_digest: str
+    oracle_manifest_digest: str
+
+
+@dataclass(frozen=True)
+class ComparatorReuseExpectation:
+    """Sweep-wide lock for comparator reuse. Any drift pays for a fresh cell."""
+
+    model: str
+    effort: str
+    sandbox_backend: str
+    runtime_digest: str | None
+    now: datetime
+    max_age: timedelta
+    tasks: Mapping[str, TaskReuseBinding]
+    skill_digests: Mapping[str, str | None]
+    ce_plugin_version: str | None
+    ce_plugin_manifest_digest: str | None
+
+
+def load_result_rows(path: Path) -> list[dict[str, Any]]:
+    """Load ``results.jsonl``; skip malformed lines the same way evolve does."""
+
+    rows: list[dict[str, Any]] = []
+    for line in path.read_text().splitlines():
+        if not line.strip():
+            continue
+        try:
+            row = json.loads(line)
+        except json.JSONDecodeError:
+            continue
+        if isinstance(row, dict):
+            rows.append(row)
+    return rows
+
+
+def current_runtime_digest() -> str | None:
+    """Harness lockfile digest exported by ``run-evolution.sh``, if present."""
+
+    value = os.environ.get("RUNTIME_DIGEST", "").strip()
+    return value or None
+
+
+def row_is_reusable_comparator(row: Mapping[str, Any], expected: ComparatorReuseExpectation) -> bool:
+    """True when ``row`` is a complete, still-valid comparator measurement."""
+
+    arm = row.get("arm")
+    if not isinstance(arm, str) or arm in CANDIDATE_ARMS or arm not in REUSABLE_COMPARATOR_ARMS:
+        return False
+    if row.get("error_kind") in REUSE_EXCLUDED_ERROR_KINDS:
+        return False
+    if row.get("error_kind") not in (None, ""):
+        return False
+    if row.get("ok") is not True:
+        return False
+    if row.get("transcript_missing") is True:
+        return False
+    if row.get("candidate_overlay_digest") not in (None, ""):
+        return False
+    recorded = _parse_recorded_at(row.get("recorded_at"))
+    if recorded is None or expected.now - recorded > expected.max_age:
+        return False
+    if row.get("model") != expected.model and row.get("benchmark_model") != expected.model:
+        return False
+    if row.get("effort") != expected.effort:
+        return False
+    if row.get("sandbox_backend") != expected.sandbox_backend:
+        return False
+    prior_runtime = row.get("runtime_digest")
+    if (
+        isinstance(prior_runtime, str)
+        and prior_runtime
+        and expected.runtime_digest
+        and prior_runtime != expected.runtime_digest
+    ):
+        return False
+
+    task_id = row.get("task")
+    binding = expected.tasks.get(task_id) if isinstance(task_id, str) else None
+    if binding is None:
+        return False
+    if row.get("task_base_sha") != binding.task_base_sha:
+        return False
+    if row.get("task_prompt_digest") != binding.task_prompt_digest:
+        return False
+    if row.get("oracle_digest") != binding.oracle_digest:
+        return False
+    if row.get("oracle_command_digest") != binding.oracle_command_digest:
+        return False
+    if row.get("oracle_manifest_digest") != binding.oracle_manifest_digest:
+        return False
+
+    if arm in CE_ARMS:
+        if row.get("ce_plugin_version") != expected.ce_plugin_version:
+            return False
+        if row.get("ce_plugin_manifest_digest") != expected.ce_plugin_manifest_digest:
+            return False
+    else:
+        expected_skill = expected.skill_digests.get(arm)
+        if not expected_skill or row.get("skill_digest") != expected_skill:
+            return False
+
+    if arm in {"review", "ce_review"}:
+        if row.get("review_evidence_valid") is not True:
+            return False
+        if not isinstance(row.get("review_score"), dict):
+            return False
+        if row.get("review_weighted_f1") is None:
+            return False
+
+    artifacts = row.get("transcript_artifacts")
+    if not isinstance(artifacts, list) or not artifacts:
+        return False
+    try:
+        for artifact in artifacts:
+            _transcript_metadata(artifact)
+    except SandboxError:
+        return False
+    return True
+
+
+def select_reusable_comparator_rows(
+    rows: Sequence[Mapping[str, Any]],
+    *,
+    expected: ComparatorReuseExpectation,
+) -> dict[CellKey, dict[str, Any]]:
+    """Index reusable rows by ``(task, arm, run)``. Conflicting duplicates drop the key."""
+
+    chosen: dict[CellKey, dict[str, Any]] = {}
+    blocked: set[CellKey] = set()
+    for row in rows:
+        if not row_is_reusable_comparator(row, expected):
+            continue
+        task_id = row["task"]
+        arm = row["arm"]
+        run = row.get("run")
+        if not isinstance(run, int) or isinstance(run, bool) or run < 0:
+            continue
+        key = (str(task_id), str(arm), run)
+        if key in blocked:
+            continue
+        previous = chosen.get(key)
+        if previous is None:
+            chosen[key] = dict(row)
+            continue
+        if _row_identity(previous) != _row_identity(row):
+            blocked.add(key)
+            chosen.pop(key, None)
+    return chosen
+
+
+def materialize_reused_row(
+    row: Mapping[str, Any],
+    *,
+    source_dir: Path,
+    dest_dir: Path,
+) -> dict[str, Any]:
+    """Copy digest-bound artifacts into this sweep's evidence dir and stamp reuse."""
+
+    source = _real_directory(source_dir, label="reuse source")
+    dest = _real_directory(dest_dir, label="reuse destination")
+    if source == dest:
+        raise SandboxError("comparator reuse cannot read and write the same results directory")
+
+    materialized = dict(row)
+    materialized["reused"] = True
+    materialized["reused_from_recorded_at"] = row.get("recorded_at")
+    materialized["recorded_at"] = datetime.now(UTC).isoformat()
+
+    artifacts = row.get("transcript_artifacts")
+    if not isinstance(artifacts, list) or not artifacts:
+        raise SandboxError("reused row is missing transcript_artifacts")
+    copied_artifacts: list[dict[str, Any]] = []
+    for artifact in artifacts:
+        copied_artifacts.append(_copy_transcript_artifact(source, dest, artifact))
+    materialized["transcript_artifacts"] = copied_artifacts
+
+    review_name = row.get("review_artifact")
+    if isinstance(review_name, str) and review_name:
+        _copy_named_artifact(source, dest, review_name, label="review artifact")
+
+    task = row.get("task")
+    arm = row.get("arm")
+    run = row.get("run")
+    if isinstance(task, str) and isinstance(arm, str) and isinstance(run, int) and not isinstance(run, bool):
+        patch_name = f"{task}-{arm}-run{run}.patch"
+        patch = source / patch_name
+        if patch.is_file() and not patch.is_symlink():
+            _copy_named_artifact(source, dest, patch_name, label="patch artifact")
+    return materialized
+
+
+def default_reuse_max_age() -> timedelta:
+    return timedelta(days=EVIDENCE_MAX_AGE_DAYS)
+
+
+def _row_identity(row: Mapping[str, Any]) -> tuple[Any, ...]:
+    return (
+        row.get("skill_digest"),
+        row.get("oracle_digest"),
+        row.get("review_weighted_f1"),
+        row.get("ce_plugin_manifest_digest"),
+        row.get("recorded_at"),
+    )
+
+
+def _parse_recorded_at(value: Any) -> datetime | None:
+    if not isinstance(value, str) or not value:
+        return None
+    try:
+        parsed = datetime.fromisoformat(value.replace("Z", "+00:00"))
+    except ValueError:
+        return None
+    if parsed.tzinfo is None:
+        parsed = parsed.replace(tzinfo=UTC)
+    return parsed.astimezone(UTC)
+
+
+def _transcript_metadata(metadata: Any) -> tuple[str, str, int]:
+    if not isinstance(metadata, dict) or set(metadata) != {"path", "sha256", "bytes", "source"}:
+        raise SandboxError("transcript artifact metadata must contain only path, sha256, bytes, and source")
+    relative = metadata["path"]
+    digest = metadata["sha256"]
+    size = metadata["bytes"]
+    if metadata["source"] != PARENT_EVENT_STREAM_SOURCE:
+        raise SandboxError("transcript artifact source is not the parent event stream")
+    if not isinstance(relative, str) or not isinstance(digest, str) or not re.fullmatch(r"[0-9a-f]{64}", digest):
+        raise SandboxError("transcript artifact metadata is malformed")
+    if not isinstance(size, int) or isinstance(size, bool) or size < 0 or size > MAX_TRANSCRIPT_BYTES:
+        raise SandboxError("transcript artifact byte count is out of range")
+    relative_path = PurePosixPath(relative)
+    if (
+        relative_path.is_absolute()
+        or len(relative_path.parts) != 2
+        or relative_path.parts[0] != "transcripts"
+        or any(part in {"", ".", ".."} for part in relative_path.parts)
+        or _TRANSCRIPT_NAME.fullmatch(relative_path.parts[1]) is None
+    ):
+        raise SandboxError(f"unsafe transcript artifact path: {relative!r}")
+    return relative, digest, size
+
+
+def _real_directory(path: Path, *, label: str) -> Path:
+    resolved = path.expanduser()
+    try:
+        metadata = resolved.lstat()
+    except OSError as exc:
+        raise SandboxError(f"{label} is unavailable: {resolved}: {exc}") from exc
+    if stat.S_ISLNK(metadata.st_mode) or not stat.S_ISDIR(metadata.st_mode):
+        raise SandboxError(f"{label} must be a real directory: {resolved}")
+    return resolved.resolve()
+
+
+def _copy_transcript_artifact(source: Path, dest: Path, metadata: Mapping[str, Any]) -> dict[str, Any]:
+    relative, expected_digest, expected_size = _transcript_metadata(metadata)
+    source_file = _regular_file(source / Path(*PurePosixPath(relative).parts), label="transcript")
+    actual_size = source_file.stat().st_size
+    if actual_size != expected_size:
+        raise SandboxError(f"reused transcript size drifted: {relative}")
+    digest = _sha256_file(source_file)
+    if digest != expected_digest:
+        raise SandboxError(f"reused transcript digest drifted: {relative}")
+    dest_dir = dest / "transcripts"
+    dest_dir.mkdir(mode=0o700, exist_ok=True)
+    dest_dir.chmod(0o700)
+    destination = dest_dir / PurePosixPath(relative).name
+    _copy_owner_only(source_file, destination)
+    return {"path": relative, "sha256": digest, "bytes": expected_size, "source": PARENT_EVENT_STREAM_SOURCE}
+
+
+def _copy_named_artifact(source: Path, dest: Path, name: str, *, label: str) -> None:
+    relative = PurePosixPath(name)
+    if relative.is_absolute() or len(relative.parts) != 1 or relative.parts[0] in {"", ".", ".."}:
+        raise SandboxError(f"unsafe {label} path: {name!r}")
+    source_file = _regular_file(source / name, label=label)
+    _copy_owner_only(source_file, dest / name)
+
+
+def _regular_file(path: Path, *, label: str) -> Path:
+    try:
+        metadata = path.lstat()
+    except OSError as exc:
+        raise SandboxError(f"{label} is missing: {path}: {exc}") from exc
+    if stat.S_ISLNK(metadata.st_mode) or not stat.S_ISREG(metadata.st_mode):
+        raise SandboxError(f"{label} must be a regular non-symlink file: {path}")
+    return path
+
+
+def _copy_owner_only(source: Path, destination: Path) -> None:
+    if destination.exists() or destination.is_symlink():
+        raise SandboxError(f"reuse destination already exists: {destination}")
+    descriptor = os.open(
+        destination,
+        os.O_WRONLY | os.O_CREAT | os.O_EXCL | getattr(os, "O_NOFOLLOW", 0),
+        0o600,
+    )
+    try:
+        os.fchmod(descriptor, 0o600)
+        with open(source, "rb") as handle:
+            while True:
+                chunk = handle.read(1024 * 1024)
+                if not chunk:
+                    break
+                view = memoryview(chunk)
+                while view:
+                    written = os.write(descriptor, view)
+                    if written <= 0:
+                        raise OSError(f"short write while copying {source}")
+                    view = view[written:]
+        os.fsync(descriptor)
+    finally:
+        os.close(descriptor)
+
+
+def _sha256_file(path: Path) -> str:
+    digest = hashlib.sha256()
+    with open(path, "rb") as handle:
+        for chunk in iter(lambda: handle.read(1024 * 1024), b""):
+            digest.update(chunk)
+    return digest.hexdigest()
diff --git a/eval/workflow_bench/evolve.py b/eval/workflow_bench/evolve.py
index 71a2299cb..3e2774435 100644
--- a/eval/workflow_bench/evolve.py
+++ b/eval/workflow_bench/evolve.py
@@ -823,6 +823,92 @@ def _timeout_arm_key(arm: str) -> str:
     return CANDIDATE_ARMS.get(arm, arm)
 
 
+EVENTBRIDGE_INSTANCE_WINDOW_SECONDS = 86_400
+EVENTBRIDGE_STOP_RESERVE_SECONDS = 5_400
+MIN_INSTANCE_SWEEP_SECONDS = 600
+
+
+def instance_window_budget_seconds(
+    uptime_seconds: float,
+    *,
+    window_seconds: int = EVENTBRIDGE_INSTANCE_WINDOW_SECONDS,
+    reserve_seconds: int = EVENTBRIDGE_STOP_RESERVE_SECONDS,
+    min_seconds: int = MIN_INSTANCE_SWEEP_SECONDS,
+) -> int:
+    """Seconds a sweep may run before an EventBridge 24h instance stop.
+
+    The dedicated evolution box is started ~15 minutes before the Saturday
+    cron and stopped 24h later. A ``workflow_dispatch`` that lands on an
+    already-running box inherits the leftover uptime, not a fresh day.
+    Run 33962002890 dispatched Friday 10:57 UTC and was still on its last
+    review cell when the Saturday 03:00 stop cancelled the runner — 51
+    finished sessions never uploaded because a cancelled job skips even
+    ``if: always()``. Capping the in-process sweep so it *fails* (instead
+    of vanishing) leaves the reserve for the upload step.
+    """
+
+    if window_seconds < 1 or reserve_seconds < 0 or min_seconds < 1:
+        raise ValueError("instance window and minimum must be positive; reserve must be non-negative")
+    if not math.isfinite(uptime_seconds) or uptime_seconds < 0:
+        raise ValueError("uptime must be a finite non-negative number")
+    leftover = int(window_seconds - uptime_seconds - reserve_seconds)
+    if leftover < min_seconds:
+        raise ValueError(
+            f"instance window has only {leftover}s left after a {reserve_seconds}s "
+            f"upload reserve (uptime {uptime_seconds:.0f}s of {window_seconds}s); "
+            f"need at least {min_seconds}s"
+        )
+    return leftover
+
+
+def instance_window_budget_from_proc(
+    uptime_path: Path = Path("/proc/uptime"),
+    *,
+    window_seconds: int | None = None,
+    reserve_seconds: int | None = None,
+) -> int:
+    """Read host uptime and apply the EventBridge window env overrides."""
+
+    window = (
+        window_seconds
+        if window_seconds is not None
+        else int(os.environ.get("EVENTBRIDGE_INSTANCE_WINDOW_SECONDS", str(EVENTBRIDGE_INSTANCE_WINDOW_SECONDS)))
+    )
+    reserve = (
+        reserve_seconds
+        if reserve_seconds is not None
+        else int(os.environ.get("EVENTBRIDGE_STOP_RESERVE_SECONDS", str(EVENTBRIDGE_STOP_RESERVE_SECONDS)))
+    )
+    try:
+        uptime = float(uptime_path.read_text().split()[0])
+    except (OSError, IndexError, ValueError) as exc:
+        raise ValueError(f"cannot read instance uptime from {uptime_path}: {exc}") from exc
+    return instance_window_budget_seconds(uptime, window_seconds=window, reserve_seconds=reserve)
+
+
+def remaining_runtime_seconds(*, max_runtime_seconds: int | None, started_monotonic: float) -> int | None:
+    """Seconds left in an optional wall-clock cap, or None when uncapped."""
+
+    if max_runtime_seconds is None:
+        return None
+    if max_runtime_seconds < 1:
+        raise ValueError("max runtime must be positive")
+    leftover = max_runtime_seconds - (time.monotonic() - started_monotonic)
+    return max(0, int(leftover))
+
+
+def capped_timeout_seconds(requested: int, remaining: int | None) -> int:
+    """Clamp one managed-process timeout to the leftover instance window."""
+
+    if requested < 1:
+        raise ValueError("requested timeout must be positive")
+    if remaining is None:
+        return requested
+    if remaining < 1:
+        raise ValueError("no time remains in the instance window")
+    return min(requested, remaining)
+
+
 def generation_timeout_seconds(
     *,
     task_count: int,
@@ -877,6 +963,7 @@ def runner_argv(
     task_bindings: list[dict[str, Any]],
     target_base_digests: dict[str, str],
     proposer_model: str | None = None,
+    reuse_results: Path | None = None,
 ) -> list[str]:
     incumbent_arms = resolve_incumbent_arms(overlay_dir, args.arms)
     paired_arms = executed_benchmark_arms(incumbent_arms)
@@ -927,6 +1014,8 @@ def runner_argv(
         argv += ["--ce-plugin-dir", str(args.ce_plugin_dir), "--ce-plugin-version", args.ce_plugin_version]
     if args.unsafe_no_bwrap:
         argv.append("--unsafe-no-bwrap")
+    if reuse_results is not None:
+        argv += ["--reuse-results", str(reuse_results)]
     return argv
 
 
@@ -1199,6 +1288,13 @@ def _require_finite_metric(value: Any, name: str, *, nullable: bool = False, max
         raise ValueError(f"promotion has invalid {name}")
 
 
+def _positive_int(value: str) -> int:
+    parsed = int(value)
+    if parsed < 1:
+        raise argparse.ArgumentTypeError(f"{value} is not a positive integer")
+    return parsed
+
+
 def build_parser() -> argparse.ArgumentParser:
     parser = argparse.ArgumentParser(description=__doc__)
     parser.add_argument("--tasks", required=True, type=Path)
@@ -1237,7 +1333,8 @@ def build_parser() -> argparse.ArgumentParser:
         "--seed-results",
         type=Path,
         default=None,
-        help="prior wfbench results dir used as generation-0 proposer evidence",
+        help="prior wfbench results dir used as generation-0 proposer evidence "
+        "and as --reuse-results for unchanged incumbent/CE cells",
     )
     parser.add_argument(
         "--initial-overlay",
@@ -1271,6 +1368,13 @@ def build_parser() -> argparse.ArgumentParser:
         default=runner_sessions.SESSION_TIMEOUT_SECONDS,
         help="per session, seconds",
     )
+    parser.add_argument(
+        "--max-runtime-seconds",
+        type=_positive_int,
+        default=None,
+        help="wall-clock cap for the whole evolve process (CI sets this from "
+        "instance uptime so the sweep exits before EventBridge stops the box)",
+    )
     parser.add_argument("--base-url", default=None)
     parser.add_argument(
         "--anthropic-api-key",
@@ -1404,6 +1508,7 @@ def _run_generations(
 ) -> int:
     out_root = args.out_root or Path("results") / time.strftime("wfevolve-%Y%m%d-%H%M%S")
     out_root.mkdir(parents=True, exist_ok=True)
+    started_monotonic = time.monotonic()
     evidence_dir: Path | None = args.seed_results
     # Only a proposal this driver wrote in this run is stageable: a
     # --seed-results tree is an operator-supplied path, and its sibling
@@ -1513,6 +1618,16 @@ def _run_generations(
             print(f"[gen {generation}] promotion targets contain uncommitted or drifted bytes")
             return 1
         print(f"[gen {generation}] benchmarking candidate…")
+        leftover = remaining_runtime_seconds(
+            max_runtime_seconds=args.max_runtime_seconds,
+            started_monotonic=started_monotonic,
+        )
+        if leftover is not None and leftover < MIN_INSTANCE_SWEEP_SECONDS:
+            print(
+                f"[gen {generation}] stopping with {leftover}s left before the "
+                f"instance window ends; partial evidence is in {out_root}/"
+            )
+            return 1
         benchmark_argv = runner_argv(
             args,
             bench_dir,
@@ -1520,20 +1635,30 @@ def _run_generations(
             task_bindings=selected_tasks,
             target_base_digests=target_base_digests,
             proposer_model=generation_proposer_model,
+            reuse_results=evidence_dir,
         )
         benchmark_command = (
             benchmark_argv
             if sandbox_backend == "host-unsafe"
             else pid_namespace_command(benchmark_argv, bwrap_bin=bwrap_bin)
         )
-        bench = run_managed(
-            benchmark_command,
-            timeout=generation_timeout_seconds(
+        sweep_timeout = capped_timeout_seconds(
+            generation_timeout_seconds(
                 task_count=len(selected_task_rows),
                 runs=args.runs,
                 session_timeout=args.timeout,
                 incumbent_arms=incumbent_arms,
             ),
+            leftover,
+        )
+        if leftover is not None:
+            print(
+                f"[gen {generation}] sweep timeout {sweep_timeout}s "
+                f"(instance window leftover {leftover}s)"
+            )
+        bench = run_managed(
+            benchmark_command,
+            timeout=sweep_timeout,
             env=runner_environment(args),
             require_pid_namespace=sandbox_backend == "bwrap",
             # The sweep is the multi-hour phase; without this its per-run
@@ -1545,7 +1670,13 @@ def _run_generations(
             # The sweep runs with GITNEXUS_BENCH_ANTHROPIC_API_KEY in its environment,
             # so its detail/stderr tail is a token-bearing sink like any other.
             detail = redacted_failure(args, str(bench.detail or bench.stderr_tail[-1000:]))
-            print(f"[gen {generation}] benchmark run failed ({bench.state}, exit {bench.returncode}): {detail}")
+            if leftover is not None and bench.state == "timeout":
+                print(
+                    f"[gen {generation}] benchmark hit the instance-window budget "
+                    f"({sweep_timeout}s); partial evidence is in {bench_dir}: {detail}"
+                )
+            else:
+                print(f"[gen {generation}] benchmark run failed ({bench.state}, exit {bench.returncode}): {detail}")
             return 1
         promotion = json.loads((bench_dir / "promotion.json").read_text())
         for line in summarize_gate(promotion):
diff --git a/eval/workflow_bench/run-evolution.sh b/eval/workflow_bench/run-evolution.sh
index c9d2a77a1..396fdac28 100755
--- a/eval/workflow_bench/run-evolution.sh
+++ b/eval/workflow_bench/run-evolution.sh
@@ -15,6 +15,8 @@
 #   MODEL PROPOSER_MODEL EFFORT GENERATIONS RUNS WORKERS PROVIDER
 #   EVOLUTION_PROFILE CE_PLUGIN_DIR CE_PLUGIN_VERSION
 #   INCLUDE_EXPENSIVE SEED_RESULTS CLAUDE_BIN OUT_ROOT
+#   CI (caps --max-runtime-seconds from /proc/uptime)
+#   EVENTBRIDGE_INSTANCE_WINDOW_SECONDS EVENTBRIDGE_STOP_RESERVE_SECONDS
 #   UNSAFE_NO_BWRAP=1 (local review diagnostics only)
 #   GITNEXUS_BENCH_ANTHROPIC_API_KEY (legacy GITNEXUS_BENCH_AUTH_TOKEN)
 #   GITNEXUS_BENCH_OPENAI_API_KEY
@@ -199,6 +201,20 @@ if ((dry_run)); then
   exit 0
 fi
 
+# A cancelled GitHub job skips even `if: always()`, so evidence dies with the
+# runner. The evolution box is EventBridge-stopped 24h after boot; a Friday
+# dispatch inherits leftover uptime. Cap the sweep so it fails in-process and
+# the upload step still runs (run 33962002890).
+if [[ -n "${CI:-}" && -r /proc/uptime ]]; then
+  remaining="$(
+    cd "${eval_dir}"
+    uv run --locked --extra dev python -c \
+      'from workflow_bench.evolve import instance_window_budget_from_proc; print(instance_window_budget_from_proc())'
+  )"
+  cmd+=(--max-runtime-seconds "${remaining}")
+  echo "Capping the sweep to ${remaining}s so the instance-window reserve can upload evidence." >&2
+fi
+
 mkdir -p "${out_root}"
 source_sha="$(git -C "${eval_dir}/.." rev-parse HEAD)"
 runtime_digest="$(
@@ -220,5 +236,9 @@ SOURCE_SHA="${source_sha}" RUNTIME_DIGEST="${runtime_digest}" SANDBOX_BACKEND="$
   }, null, 2) + "\n")' "${out_root}/runtime-provenance.json"
 
 export PYTHONUNBUFFERED=1
+# The runner stamps this on every results.jsonl row and refuses to reuse a
+# comparator cell when a prior row's digest disagrees. Keep it on the evolve
+# process, not only in the provenance JSON sidecar.
+export RUNTIME_DIGEST="${runtime_digest}"
 cd "${eval_dir}"
 exec "${cmd[@]}"
diff --git a/eval/workflow_bench/runner.py b/eval/workflow_bench/runner.py
index 82185186c..f78394bf9 100644
--- a/eval/workflow_bench/runner.py
+++ b/eval/workflow_bench/runner.py
@@ -57,6 +57,15 @@ from typing import Any
 
 import yaml
 
+from .comparator_reuse import (
+    ComparatorReuseExpectation,
+    TaskReuseBinding,
+    current_runtime_digest,
+    default_reuse_max_age,
+    load_result_rows,
+    materialize_reused_row,
+    select_reusable_comparator_rows,
+)
 from .evolution import (
     CANDIDATE_ARMS,
     EVIDENCE_MAX_AGE_DAYS,
@@ -121,6 +130,7 @@ from .runner_artifacts import (
     enforce_phase_workspace,
     enforce_work_evidence,
     implementation_diff_digest,
+    copy_isolated_tree,
     make_worktree,
     new_plan_doc,
     parse_shortstat as parse_shortstat,
@@ -884,6 +894,8 @@ class TaskCellContext:
     candidate_overlay: Path | None
     overlay_digest: str | None
     sandbox_backend: str = "bwrap"
+    clone_template: Path | None = None
+    sanitized_head: str | None = None
 
 
 def run_cell(ctx: TaskCellContext, run_idx: int, arm: str) -> dict[str, Any]:
@@ -908,8 +920,14 @@ def run_cell(ctx: TaskCellContext, run_idx: int, arm: str) -> dict[str, Any]:
             raise RuntimeError("sanitized graph snapshot is unavailable")
         if ctx.asset_snapshot is None:
             raise RuntimeError("task asset snapshot is unavailable")
-        worktree = make_worktree(ctx.repo, ctx.task_sha, ctx.trees_dir)
-        sanitized_head = sanitize_clone_for_hidden_oracles(worktree)
+        if ctx.clone_template is not None:
+            if not ctx.sanitized_head:
+                raise RuntimeError("clone template is missing its sanitized HEAD")
+            worktree = copy_isolated_tree(ctx.clone_template, ctx.trees_dir)
+            sanitized_head = ctx.sanitized_head
+        else:
+            worktree = make_worktree(ctx.repo, ctx.task_sha, ctx.trees_dir)
+            sanitized_head = sanitize_clone_for_hidden_oracles(worktree)
         ctx.graph_snapshot.materialize(worktree, sanitized_head=sanitized_head)
         dependency_mounts = stage_task_assets(
             task,
@@ -1057,6 +1075,7 @@ def run_cell(ctx: TaskCellContext, run_idx: int, arm: str) -> dict[str, Any]:
                 "task_prompt_digest": hashlib.sha256(task["prompt"].encode()).hexdigest(),
                 "skill_digest": expected_skill_digest,
                 "candidate_overlay_digest": (ctx.overlay_digest if arm in CANDIDATE_ARMS else None),
+                "runtime_digest": current_runtime_digest(),
                 "recorded_at": datetime.now(UTC).isoformat(),
             }
         )
@@ -1557,6 +1576,15 @@ def build_parser() -> argparse.ArgumentParser:
     parser.add_argument("--task-bindings-json", default=None, help=argparse.SUPPRESS)
     parser.add_argument("--promotion-target-bases-json", default=None, help=argparse.SUPPRESS)
     parser.add_argument("--unsafe-no-bwrap", action="store_true", help=argparse.SUPPRESS)
+    parser.add_argument(
+        "--reuse-results",
+        type=Path,
+        default=None,
+        help="prior wfbench results dir whose incumbent/CE rows may be reused "
+        "when model, effort, tasks, oracles, skill bytes, and CE plugin still "
+        "match. Candidate arms always run. Used by evolve.py so a weekly "
+        "generation does not re-pay for an unchanged comparator.",
+    )
     return parser
 
 
@@ -1684,6 +1712,49 @@ def main() -> None:
         gateway.__exit__(None, None, None)
 
 
+def _comparator_reuse_expectation(
+    *,
+    args: argparse.Namespace,
+    tasks: Sequence[Any],
+    task_bindings: Sequence[Mapping[str, Any]],
+    oracle_snapshots: Sequence[Any],
+    sandbox_backend: str,
+    ce_plugin_snapshot: CePluginSnapshot | None,
+) -> ComparatorReuseExpectation:
+    """Bind this sweep's immutable identity for comparator-row reuse."""
+
+    skill_digests: dict[str, str | None] = {}
+    for arm in args.arms:
+        execution = CANDIDATE_ARMS.get(arm, arm)
+        if execution in EVALUATED_ARM_SKILLS:
+            skill_digests[arm] = skill_fingerprint(HARNESS_ROOT, execution)
+        else:
+            skill_digests[arm] = None
+    task_locks: dict[str, TaskReuseBinding] = {}
+    for task, binding, oracle in zip(tasks, task_bindings, oracle_snapshots, strict=True):
+        task_locks[str(task["id"])] = TaskReuseBinding(
+            task_base_sha=str(binding["resolved_sha"]),
+            task_prompt_digest=hashlib.sha256(str(task["prompt"]).encode()).hexdigest(),
+            oracle_digest=oracle.digest,
+            oracle_command_digest=oracle.command_digest,
+            oracle_manifest_digest=oracle.manifest_digest,
+        )
+    return ComparatorReuseExpectation(
+        model=args.model,
+        effort=args.effort,
+        sandbox_backend=sandbox_backend,
+        runtime_digest=current_runtime_digest(),
+        now=datetime.now(UTC),
+        max_age=default_reuse_max_age(),
+        tasks=task_locks,
+        skill_digests=skill_digests,
+        ce_plugin_version=ce_plugin_snapshot.version if ce_plugin_snapshot is not None else None,
+        ce_plugin_manifest_digest=(
+            ce_plugin_snapshot.manifest_digest if ce_plugin_snapshot is not None else None
+        ),
+    )
+
+
 def _run_sweep(
     args: argparse.Namespace,
     *,
@@ -1740,8 +1811,35 @@ def _run_sweep(
         except (OSError, SandboxError, ValueError) as exc:
             parser.error(str(exc))
             raise AssertionError("ArgumentParser.error() returned unexpectedly")
+        reuse_source = args.reuse_results.expanduser().resolve() if args.reuse_results is not None else None
+        reusable_rows: dict[tuple[str, str, int], dict[str, Any]] = {}
+        if reuse_source is not None:
+            if reuse_source == out_dir.resolve():
+                parser.error("--reuse-results cannot be this sweep's --out directory")
+                raise AssertionError("ArgumentParser.error() returned unexpectedly")
+            results_file = reuse_source / "results.jsonl"
+            if results_file.is_symlink() or not results_file.is_file():
+                parser.error("--reuse-results must contain a regular results.jsonl")
+                raise AssertionError("ArgumentParser.error() returned unexpectedly")
+            reusable_rows = select_reusable_comparator_rows(
+                load_result_rows(results_file),
+                expected=_comparator_reuse_expectation(
+                    args=args,
+                    tasks=tasks,
+                    task_bindings=task_bindings,
+                    oracle_snapshots=oracle_snapshots,
+                    sandbox_backend=sandbox_backend,
+                    ce_plugin_snapshot=ce_plugin_snapshot,
+                ),
+            )
+            print(
+                f"reuse-results {reuse_source}: {len(reusable_rows)} comparator "
+                f"cell(s) match this sweep; candidate arms always run"
+            )
         graph_snapshots: dict[tuple[str, str], SanitizedGraphSnapshot] = {}
         graph_snapshot_errors: dict[tuple[str, str], BaseException] = {}
+        clone_templates: dict[tuple[str, str], tuple[Path, str]] = {}
+        clone_template_errors: dict[tuple[str, str], BaseException] = {}
         for task, task_binding, oracle_snapshot in zip(
             tasks,
             task_bindings,
@@ -1752,41 +1850,79 @@ def _run_sweep(
                 break
             repo = Path(task_binding["repo_identity"])
             task_sha = task_binding["resolved_sha"]
+            per_arm: dict[str, list[dict[str, Any]]] = {a: [] for a in args.arms}
+            planned = [(run_idx, arm) for run_idx in range(args.runs) for arm in args.arms]
+            reused_records: list[tuple[int, str, dict[str, Any]]] = []
+            paid_cells: list[tuple[int, str]] = []
+            for run_idx, arm in planned:
+                prior = reusable_rows.get((task["id"], arm, run_idx))
+                if prior is None or reuse_source is None:
+                    paid_cells.append((run_idx, arm))
+                    continue
+                try:
+                    reused_records.append(
+                        (
+                            run_idx,
+                            arm,
+                            materialize_reused_row(prior, source_dir=reuse_source, dest_dir=out_dir),
+                        )
+                    )
+                except (OSError, SandboxError, ValueError) as exc:
+                    print(
+                        f"[{task['id']}][{arm}][run {run_idx}] comparator reuse "
+                        f"failed ({exc}); running a paid cell"
+                    )
+                    paid_cells.append((run_idx, arm))
+
             asset_snapshot: TaskAssetSnapshot | None = None
             asset_snapshot_error: BaseException | None = None
             graph_key = (str(repo), task_sha)
             graph_snapshot: SanitizedGraphSnapshot | None = graph_snapshots.get(graph_key)
             graph_snapshot_error: BaseException | None = graph_snapshot_errors.get(graph_key)
-            try:
-                validate_no_prebuilt_graph_assets(task)
-                if graph_snapshot is None and graph_snapshot_error is None:
-                    graph_snapshot = prepare_sanitized_graph(
+            clone_template: Path | None = None
+            template_head: str | None = None
+            if paid_cells:
+                try:
+                    validate_no_prebuilt_graph_assets(task)
+                    if graph_key not in clone_templates and graph_key not in clone_template_errors:
+                        template = make_worktree(repo, task_sha, Path(trees))
+                        template_head = sanitize_clone_for_hidden_oracles(template)
+                        clone_templates[graph_key] = (template, template_head)
+                    if graph_key in clone_templates:
+                        clone_template, template_head = clone_templates[graph_key]
+                    if graph_key in clone_template_errors and graph_snapshot_error is None:
+                        graph_snapshot_error = clone_template_errors[graph_key]
+                    if graph_snapshot is None and graph_snapshot_error is None:
+                        graph_snapshot = prepare_sanitized_graph(
+                            task,
+                            repo=repo,
+                            resolved_sha=task_sha,
+                            parent=Path(trees),
+                            cache=task_asset_cache,
+                            claude_bin=args.claude_bin,
+                            bwrap_bin=bwrap_bin,
+                            sandbox_backend=sandbox_backend,
+                            runtime_mounts=runtime_mounts,
+                            clone_template=clone_template,
+                            sanitized_head=template_head,
+                        )
+                        graph_snapshots[graph_key] = graph_snapshot
+                except (ManagedProcessError, OSError, SandboxError, RuntimeError, ValueError) as exc:
+                    graph_snapshot_error = exc
+                    graph_snapshot_errors[graph_key] = exc
+                    clone_template_errors.setdefault(graph_key, exc)
+                try:
+                    # Prepared here, once, rather than lazily inside the first cell:
+                    # TaskAssetCache is a plain dict, so a lazy build would be a
+                    # read-then-write race the moment cells stop running serially.
+                    asset_snapshot = task_asset_cache.prepare(
                         task,
                         repo=repo,
                         resolved_sha=task_sha,
-                        parent=Path(trees),
-                        cache=task_asset_cache,
-                        claude_bin=args.claude_bin,
-                        bwrap_bin=bwrap_bin,
-                        sandbox_backend=sandbox_backend,
-                        runtime_mounts=runtime_mounts,
+                        expected_dependency_binding=task_binding,
                     )
-                    graph_snapshots[graph_key] = graph_snapshot
-            except (ManagedProcessError, OSError, SandboxError, RuntimeError, ValueError) as exc:
-                graph_snapshot_error = exc
-                graph_snapshot_errors[graph_key] = exc
-            try:
-                # Prepared here, once, rather than lazily inside the first cell:
-                # TaskAssetCache is a plain dict, so a lazy build would be a
-                # read-then-write race the moment cells stop running serially.
-                asset_snapshot = task_asset_cache.prepare(
-                    task,
-                    repo=repo,
-                    resolved_sha=task_sha,
-                    expected_dependency_binding=task_binding,
-                )
-            except (OSError, SandboxError, ValueError) as exc:
-                asset_snapshot_error = exc
+                except (OSError, SandboxError, ValueError) as exc:
+                    asset_snapshot_error = exc
             cell_context = TaskCellContext(
                 task=task,
                 oracle_snapshot=oracle_snapshot,
@@ -1805,9 +1941,9 @@ def _run_sweep(
                 runtime_mounts=runtime_mounts,
                 candidate_overlay=candidate_overlay,
                 overlay_digest=overlay_digest,
+                clone_template=clone_template,
+                sanitized_head=template_head,
             )
-            per_arm: dict[str, list[dict[str, Any]]] = {a: [] for a in args.arms}
-            cells = [(run_idx, arm) for run_idx in range(args.runs) for arm in args.arms]
 
             def announce(run_idx: int, arm: str) -> None:
                 nonlocal started_cells
@@ -1830,16 +1966,24 @@ def _run_sweep(
                 if failure:
                     print(failure)
 
-            outage_streak, outage_tripped = sweep_task_cells(
-                cells,
-                workers=args.workers,
-                run=partial(run_cell, cell_context),
-                on_start=announce,
-                on_record=keep,
-                outage_streak=outage_streak,
-                outage_limit=args.outage_streak,
-                cancel_event=cancel_event,
-            )
+            for run_idx, arm, record in reused_records:
+                started_cells += 1
+                print(
+                    f"[{task['id']}][{arm}][run {run_idx}] reused comparator "
+                    f"({started_cells}/{total_cells}, {(time.monotonic() - sweep_started) / 60:.0f}m elapsed)"
+                )
+                keep(run_idx, arm, record)
+            if paid_cells:
+                outage_streak, outage_tripped = sweep_task_cells(
+                    paid_cells,
+                    workers=args.workers,
+                    run=partial(run_cell, cell_context),
+                    on_start=announce,
+                    on_record=keep,
+                    outage_streak=outage_streak,
+                    outage_limit=args.outage_streak,
+                    cancel_event=cancel_event,
+                )
             results[task["id"]] = {a: aggregate(rs) for a, rs in per_arm.items() if rs}
 
     selection_report = [
diff --git a/eval/workflow_bench/runner_artifacts.py b/eval/workflow_bench/runner_artifacts.py
index 7f05e14b1..02dbd8a38 100644
--- a/eval/workflow_bench/runner_artifacts.py
+++ b/eval/workflow_bench/runner_artifacts.py
@@ -325,6 +325,58 @@ def new_plan_doc(worktree: Path, before: dict[Path, str]) -> Path:
     return changed[0]
 
 
+def _assert_self_contained_git_objects(clone: Path) -> None:
+    """Refuse clones that share pack/object bytes with another repository."""
+
+    alternates = clone / ".git" / "objects" / "info" / "alternates"
+    if alternates.exists():
+        raise RuntimeError(f"clone unexpectedly has an external object alternate: {alternates}")
+    objects = clone / ".git" / "objects"
+    if not objects.is_dir():
+        raise RuntimeError(f"clone is missing a git object store: {clone}")
+    for obj in objects.rglob("*"):
+        if obj.is_file() and obj.stat().st_nlink > 1:
+            raise RuntimeError(f"clone object is hardlinked to host storage: {obj}")
+
+
+def copy_isolated_tree(source: Path, parent: Path) -> Path:
+    """Copy a sanitized clone without sharing git objects or a ref namespace.
+
+    ``git clone --no-local`` of GitNexus plus ``sanitize_clone_for_hidden_oracles``
+    (repack/prune/fsck) is minutes per cell. After sanitization the snapshot is
+    one parentless commit; copying that tree is the isolation boundary the
+    contamination bug actually required (a private ``.git``), not a second
+    fetch of full history. Prefer ``cp --reflink=auto`` so XFS/btrfs pay COW;
+    fall back to a full copy on filesystems that cannot reflink.
+    """
+
+    try:
+        source_meta = source.expanduser().lstat()
+    except OSError as exc:
+        raise RuntimeError(f"clone template is unavailable: {source}: {exc}") from exc
+    if stat.S_ISLNK(source_meta.st_mode) or not stat.S_ISDIR(source_meta.st_mode):
+        raise RuntimeError(f"clone template must be a real directory: {source}")
+    source = source.expanduser().resolve()
+    target = Path(tempfile.mkdtemp(prefix="wfbench-", dir=parent))
+    target.rmdir()
+    try:
+        copied = run_managed(
+            ["cp", "-a", "--reflink=auto", str(source), str(target)],
+            timeout=600,
+        )
+        if not copied.ok:
+            shutil.copytree(source, target, symlinks=True, copy_function=shutil.copy2)
+        _assert_self_contained_git_objects(target)
+        return target
+    except BaseException as primary:
+        if target.exists():
+            try:
+                shutil.rmtree(target)
+            except OSError as cleanup:
+                primary.add_note(f"clone copy cleanup also failed: {type(cleanup).__name__}: {cleanup}")
+        raise
+
+
 def make_worktree(repo: Path, ref: str, parent: Path) -> Path:
     """Create a self-contained clone per benchmark arm."""
 
@@ -344,12 +396,7 @@ def make_worktree(repo: Path, ref: str, parent: Path) -> Path:
             ],
             timeout=600,
         )
-        alternates = target / ".git" / "objects" / "info" / "alternates"
-        if alternates.exists():
-            raise RuntimeError(f"clone unexpectedly has an external object alternate: {alternates}")
-        for obj in (target / ".git" / "objects").rglob("*"):
-            if obj.is_file() and obj.stat().st_nlink > 1:
-                raise RuntimeError(f"clone object is hardlinked to host storage: {obj}")
+        _assert_self_contained_git_objects(target)
         for candidate in (ref, f"origin/{ref}"):
             proc = run_managed(
                 ["git", "-C", str(target), "checkout", "--detach", "--quiet", candidate],
diff --git a/eval/workflow_bench/runner_sessions.py b/eval/workflow_bench/runner_sessions.py
index 9daef00b4..053d5e48d 100644
--- a/eval/workflow_bench/runner_sessions.py
+++ b/eval/workflow_bench/runner_sessions.py
@@ -57,6 +57,24 @@ MAX_PROGRESS_PENDING = 256
 MAX_PROGRESS_TOOL_ID_CHARS = 256
 MAX_TOOL_PREVIEW_CHARS = 800
 _SAFE_TOOL_NAME = re.compile(r"[A-Za-z0-9._:-]{1,64}")
+_GHA_WORKFLOW_COMMAND = re.compile(r"(^|[\n\r])::")
+_GHA_HASH_COMMAND = re.compile(r"##\[")
+_GHA_COMPILER_ANNOTATION = re.compile(r"\((\d+),(\d+)\):\s+error\b", re.IGNORECASE)
+
+
+def neutralize_ci_log_text(text: str) -> str:
+    """Stop GitHub Actions from promoting tool output into check annotations.
+
+    Run 33962002890 logged in-sandbox ``tsc`` failures as
+    ``file.ts(line,col): error TS2307``, which Actions parsed as workflow
+    annotations on ``.github``. The same parser treats ``::error::`` and
+    ``##[error]`` as commands. Progress previews are evidence, not CI
+    signaling, so rewrite those forms before they hit the job log.
+    """
+
+    text = _GHA_WORKFLOW_COMMAND.sub(r"\1[:]", text)
+    text = _GHA_HASH_COMMAND.sub("# [", text)
+    return _GHA_COMPILER_ANNOTATION.sub(r"(\1,\2): compiler-error", text)
 
 
 def _safe_tool_name(value: Any) -> str:
@@ -177,7 +195,9 @@ class SessionProgress:
     def _say(self, message: str) -> None:
         # Queue only: the stdout drain thread calls observe() and must not
         # block on a full log pipe (process_control.stdout_observer contract).
-        self._pending_messages.append(f"[{self.label} {self._elapsed()}] {message}")
+        self._pending_messages.append(
+            neutralize_ci_log_text(f"[{self.label} {self._elapsed()}] {message}")
+        )
         self._last_spoke = time.monotonic()
 
     def _emit_pending(self) -> None:
diff --git a/eval/workflow_bench/sanitized_graph.py b/eval/workflow_bench/sanitized_graph.py
index 3aea9e8c1..fc3d766a2 100644
--- a/eval/workflow_bench/sanitized_graph.py
+++ b/eval/workflow_bench/sanitized_graph.py
@@ -24,7 +24,7 @@ from .proposer_sandbox import (
     build_sandbox_environment,
     prepare_sandbox,
 )
-from .runner_artifacts import make_worktree, remove_clone
+from .runner_artifacts import copy_isolated_tree, make_worktree, remove_clone
 from .task_assets import TaskAssetCache, TaskAssetSnapshot, _is_harness_sandbox_copy
 
 GRAPH_ASSET_PATHS = (
@@ -360,14 +360,29 @@ def prepare_sanitized_graph(
     bwrap_bin: Path | str,
     runtime_mounts: Sequence[ReadOnlyMount],
     sandbox_backend: str = "bwrap",
+    clone_template: Path | None = None,
+    sanitized_head: str | None = None,
 ) -> SanitizedGraphSnapshot:
-    """Sanitize, index offline once, scrub, and freeze graph assets for all arms."""
+    """Sanitize, index offline once, scrub, and freeze graph assets for all arms.
+
+    When ``clone_template`` is an already-sanitized snapshot, this copies it
+    (the copy is scrubbed and indexed) so the template stays a clean cell
+    seed. Callers that already paid for ``make_worktree`` + sanitization
+    should pass that template rather than cloning GitNexus again.
+    """
 
     validate_no_prebuilt_graph_assets(task)
-    seed = make_worktree(repo, resolved_sha, parent)
+    if clone_template is not None:
+        if not isinstance(sanitized_head, str) or not sanitized_head:
+            raise SandboxError("clone template requires the sanitized HEAD")
+        seed = copy_isolated_tree(clone_template, parent)
+    else:
+        seed = make_worktree(repo, resolved_sha, parent)
+        sanitized_head = None
     primary: BaseException | None = None
     try:
-        sanitized_head = sanitize_clone_for_hidden_oracles(seed)
+        if sanitized_head is None:
+            sanitized_head = sanitize_clone_for_hidden_oracles(seed)
         _scrub_source_references(seed)
         _neutralize_target_index_inputs(seed)
         with prepare_sandbox(
diff --git a/eval/workflow_bench/tasks.review.scenarios.yaml b/eval/workflow_bench/tasks.review.scenarios.yaml
index 8ff323ed1..6e285a2bc 100644
--- a/eval/workflow_bench/tasks.review.scenarios.yaml
+++ b/eval/workflow_bench/tasks.review.scenarios.yaml
@@ -17,6 +17,9 @@ tasks:
       - { source: node_modules, target: node_modules }
       - { source: gitnexus/node_modules, target: gitnexus/node_modules }
       - { source: gitnexus-shared/node_modules, target: gitnexus-shared/node_modules }
+      # Host-built types/JS. Historical clones have no dist/, so `tsc` in the
+      # read-only workspace otherwise reports TS2307/TS6379 (run 33962002890).
+      - { source: gitnexus-shared/dist, target: gitnexus-shared/dist }
 
   - <<: *review_case
     id: review-pr-2794-defect
diff --git a/eval/workflow_bench/tasks.scenarios.yaml b/eval/workflow_bench/tasks.scenarios.yaml
index af4755f88..59448ae4f 100644
--- a/eval/workflow_bench/tasks.scenarios.yaml
+++ b/eval/workflow_bench/tasks.scenarios.yaml
@@ -44,6 +44,11 @@ tasks:
         target: gitnexus/node_modules
       - source: gitnexus-shared/node_modules
         target: gitnexus-shared/node_modules
+      # Host-built types/JS. The clone has no dist/, and node_modules/gitnexus-shared
+      # is a relative symlink into that unbuilt tree — without this mount, in-sandbox
+      # `tsc --noEmit` / vitest fail with TS2307 / TS6379 (run 33962002890).
+      - source: gitnexus-shared/dist
+        target: gitnexus-shared/dist
     prompt: >
       Add -j as a short alias for --json on the gitnexus status command
       (gitnexus/src/cli/index.ts), and cover the alias with a unit test in
diff --git a/gitnexus/test/unit/skill-evolution-workflow.test.ts b/gitnexus/test/unit/skill-evolution-workflow.test.ts
index b10313e42..5b3890c3a 100644
--- a/gitnexus/test/unit/skill-evolution-workflow.test.ts
+++ b/gitnexus/test/unit/skill-evolution-workflow.test.ts
@@ -270,12 +270,13 @@ describe('gitnexus skill-evolution workflow contract', () => {
   });
 
   it('passes the cell concurrency through to the benchmark', () => {
-    // The lane is serial unless told otherwise: concurrency only pays off when
-    // the runner has the vCPUs for it, and a cell starved of CPU drifts toward
-    // its session timeout, which the gate counts as an excluded run.
+    // Dispatch defaults to 3. Scheduled runs still fall back to serial unless
+    // GITNEXUS_EVOLUTION_WORKERS is set — a cell starved of CPU that hits the
+    // session ceiling is an excluded run the gate refuses.
     expect(evolveJob?.env?.WORKERS).toBe(
       "${{ inputs.workers || vars.GITNEXUS_EVOLUTION_WORKERS || '1' }}",
     );
+    expect(workflow).toMatch(/workers:\n(?:[^\n]*\n){0,4}        default: '3'/);
   });
 
   it('seeds from the newest usable completed main run, including failed runs', () => {
@@ -572,6 +573,14 @@ exit 1`);
     // uploads. The job must finish inside that window even when the schedule
     // fires late (the 2026-08-01 run was queued 65 minutes after the cron).
     expect(jobBudget as number).toBeLessThanOrEqual(21 * 60);
+    // A Friday dispatch inherits leftover uptime. The shared entrypoint — not
+    // the workflow YAML — must cap the sweep so it fails in-process and the
+    // always() upload still runs (run 33962002890).
+    const script = readFileSync(path.join(REPO_ROOT, 'eval/workflow_bench/run-evolution.sh'), 'utf8');
+    expect(script).toContain('--max-runtime-seconds');
+    expect(script).toContain('instance_window_budget_from_proc');
+    expect(script).toContain('export RUNTIME_DIGEST');
+    expect(workflow).toContain('--max-runtime-seconds');
   });
 
   it('uploads benchmark evidence unconditionally, on a path it addresses itself', () => {