diff --git a/.agents/skills/lib_py/delegation/publish_event.py b/.agents/skills/lib_py/delegation/publish_event.py
index 512b635..0a65d16 100755
--- a/.agents/skills/lib_py/delegation/publish_event.py
+++ b/.agents/skills/lib_py/delegation/publish_event.py
@@ -205,6 +205,15 @@ def main(argv=None) -> int:
                         help="force retain=True (auto for completed/error)")
     parser.add_argument("--registry-dir", default=DEFAULT_REGISTRY_DIR)
     parser.add_argument("--attempts", type=int, default=3)
+    parser.add_argument("--finalize-report", default=None, metavar="PATH",
+                        help="atomically finalize this report and declare its "
+                             "completion manifest before publishing")
+    parser.add_argument("--side-effect", action="append", default=[], dest="side_effects",
+                        metavar="KIND=REFERENCE",
+                        help="evidence for an external side effect this job performed")
+    parser.add_argument("--attempt-id", type=int, default=None,
+                        help="attempt this finalization belongs to (default: the "
+                             "job's current iteration)")
     parser.add_argument("-v", "--verbose", action="store_true")
     args = parser.parse_args(argv)
 
@@ -227,6 +236,33 @@ def main(argv=None) -> int:
         logger.error("no job to publish for (unknown --job or no pending job)")
         return 1
 
+    # Finalize before publishing: a `completed` event whose report is still being
+    # written would invite exactly the partial-report adoption the contract
+    # forbids. Failing here fails the publish, on purpose.
+    if args.finalize_report:
+        from lib_py.loop import finalize  # local import: optional dependency of this CLI
+
+        try:
+            side_effects = finalize.parse_side_effects(args.side_effects)
+        except ValueError as exc:
+            logger.error("%s", exc)
+            return 1
+        attempt_id = args.attempt_id
+        if attempt_id is None:
+            try:
+                attempt_id = load_job(job_id, args.registry_dir).get("iteration", 1)
+            except FileNotFoundError:
+                attempt_id = 1
+        try:
+            manifest = finalize.finalize_report(
+                args.finalize_report, job_id, attempt_id,
+                side_effects=side_effects, declared_by="agent")
+        except (OSError, FileNotFoundError) as exc:
+            logger.error("could not finalize report: %s", exc)
+            return 1
+        logger.info("finalized %s (sha256 %s...)", manifest["report_path"],
+                    manifest["sha256"][:12])
+
     try:
         prepared = prepare_event(
             job_id=job_id,
diff --git a/.agents/skills/lib_py/loop/finalize.py b/.agents/skills/lib_py/loop/finalize.py
new file mode 100644
index 0000000..3445502
--- /dev/null
+++ b/.agents/skills/lib_py/loop/finalize.py
@@ -0,0 +1,158 @@
+"""Report finalization: the completion manifest.
+
+Who writes this matters more than what is in it. If the watcher computed the
+hash itself, the manifest would attest only that the watcher saw a stable file
+-- self-certification, which is exactly the evidence shape a reviewer rejected
+earlier in this issue. So the side that knows the work finished declares it, and
+the reader independently re-derives the hash rather than trusting the number in
+the file.
+
+Consequence, and it is the useful one: an agent that declares nothing leaves no
+manifest, a missing manifest already holds, and the explicit-event path is
+therefore preserved for unsupported agents without any special case.
+
+    writing            report-final.md.tmp is being written
+    stable_candidate   the file stopped changing (a filter, never an authority)
+    finalized          atomically renamed, and this manifest exists
+"""
+from __future__ import annotations
+
+import hashlib
+import json
+import os
+import tempfile
+import time
+from pathlib import Path
+from typing import Any, Dict, List, Optional
+
+MANIFEST_NAME = "report-manifest.json"
+SCHEMA_VERSION = "1.0.0"
+
+
+def manifest_path(report_path) -> Path:
+    """The manifest sits beside the report it describes."""
+    return Path(report_path).parent / MANIFEST_NAME
+
+
+def manifest_in(report_dir) -> Path:
+    return Path(report_dir) / MANIFEST_NAME
+
+
+def sha256_of(path) -> str:
+    digest = hashlib.sha256()
+    with open(path, "rb") as fh:
+        for chunk in iter(lambda: fh.read(65536), b""):
+            digest.update(chunk)
+    return digest.hexdigest()
+
+
+def _atomic_write(path: Path, text: str) -> None:
+    path.parent.mkdir(parents=True, exist_ok=True)
+    fd, tmp = tempfile.mkstemp(dir=str(path.parent), prefix="." + path.name + ".", suffix=".tmp")
+    try:
+        with os.fdopen(fd, "w", encoding="utf-8") as fh:
+            fh.write(text)
+            fh.flush()
+            os.fsync(fh.fileno())
+        os.replace(tmp, path)
+    except BaseException:
+        if os.path.exists(tmp):
+            os.unlink(tmp)
+        raise
+
+
+def parse_side_effects(raw: Optional[List[str]]) -> List[Dict[str, str]]:
+    """`kind=reference` pairs from the command line into evidence entries."""
+    out = []
+    for item in raw or []:
+        kind, _, reference = str(item).partition("=")
+        kind = kind.strip()
+        if not kind or not reference.strip():
+            raise ValueError("side effect must be '<kind>=<reference>', got {!r}".format(item))
+        out.append({"kind": kind, "reference": reference.strip(),
+                    "verified_at": time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime())})
+    return out
+
+
+def finalize_report(report_path, job_id, attempt_id, side_effects=None,
+                    declared_by="agent") -> Dict[str, Any]:
+    """Promote a report to finalized and declare the manifest.
+
+    If `<report>.tmp` exists it is renamed into place first, so a reader can
+    never observe a half-written report as finalized. The rename is what makes
+    the transition atomic; the manifest is what makes it attributable.
+    """
+    report_path = Path(report_path)
+    staged = report_path.with_name(report_path.name + ".tmp")
+    if staged.exists():
+        os.replace(str(staged), str(report_path))
+    if not report_path.exists():
+        raise FileNotFoundError("no report to finalize at {}".format(report_path))
+
+    manifest = {
+        "schema_version": SCHEMA_VERSION,
+        "job_id": job_id,
+        "attempt_id": attempt_id,
+        "report_path": str(report_path),
+        "sha256": sha256_of(report_path),
+        "finalized_at": time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime()),
+        "side_effects": list(side_effects or []),
+        "declared_by": declared_by,
+    }
+    _atomic_write(manifest_path(report_path), json.dumps(manifest, indent=2,
+                                                         ensure_ascii=False) + "\n")
+    return manifest
+
+
+class ManifestVerdict(object):
+    __slots__ = ("ok", "reason", "manifest")
+
+    def __init__(self, ok, reason, manifest=None):
+        self.ok = ok
+        self.reason = reason
+        self.manifest = manifest
+
+
+def verify_manifest(report_dir, job_id, expected_attempt=None,
+                    expected_artifacts=None) -> ManifestVerdict:
+    """Read a manifest and check it against the world, not against itself.
+
+    The hash is recomputed from the file on disk. A report rewritten after the
+    declaration therefore invalidates it, which is the contract: a new body needs
+    a new finalization.
+    """
+    path = manifest_in(report_dir)
+    if not path.exists():
+        return ManifestVerdict(False, "no completion manifest")
+
+    try:
+        manifest = json.loads(path.read_text(encoding="utf-8"))
+    except Exception as exc:
+        return ManifestVerdict(False, "manifest is unreadable: {}".format(exc))
+
+    if manifest.get("schema_version") != SCHEMA_VERSION:
+        return ManifestVerdict(False, "unsupported manifest schema {!r}".format(
+            manifest.get("schema_version")))
+    if manifest.get("job_id") != job_id:
+        return ManifestVerdict(False, "manifest belongs to job {!r}".format(manifest.get("job_id")))
+    if expected_attempt is not None and manifest.get("attempt_id") != expected_attempt:
+        return ManifestVerdict(False, "manifest belongs to attempt {!r}, not {!r}".format(
+            manifest.get("attempt_id"), expected_attempt))
+
+    report = Path(manifest.get("report_path") or "")
+    if not report.exists():
+        return ManifestVerdict(False, "the finalized report is gone: {}".format(report))
+    actual = sha256_of(report)
+    if actual != manifest.get("sha256"):
+        return ManifestVerdict(
+            False, "report changed after finalization (declared {}, found {})".format(
+                str(manifest.get("sha256"))[:12], actual[:12]))
+
+    # A job that declared side effects must show evidence for every one of them.
+    # Partial evidence is no evidence: the work is not known to be complete.
+    declared = {e.get("kind") for e in manifest.get("side_effects") or []}
+    missing = [a for a in (expected_artifacts or []) if a not in declared]
+    if missing:
+        return ManifestVerdict(False, "no side-effect evidence for {}".format(missing))
+
+    return ManifestVerdict(True, "manifest verified", manifest)
diff --git a/tests/test_issue5_phase2b_autocomplete.py b/tests/test_issue5_phase2b_autocomplete.py
index 45cbd64..818a5d3 100644
--- a/tests/test_issue5_phase2b_autocomplete.py
+++ b/tests/test_issue5_phase2b_autocomplete.py
@@ -138,3 +138,136 @@ def test_x05_the_explicit_event_path_is_untouched_by_default(mam_sandbox, tmp_pa
     record = _load(reg, job_id)
     assert record["status"] == "completed"
     assert "completed_by" not in record, "an explicit completion carries no auto marker"
+
+
+# ==============================================================================
+# 2. finalize — declared by the agent, re-derived by the reader
+# ==============================================================================
+
+def _report(tmp_path, body="done\n", staged=False):
+    d = tmp_path / "claude-reports"
+    d.mkdir(parents=True, exist_ok=True)
+    path = d / "report-final.md"
+    (path.with_name(path.name + ".tmp") if staged else path).write_text(body, encoding="utf-8")
+    return path
+
+
+def test_finalize_promotes_a_staged_report_atomically(tmp_path):
+    """A reader must never see a half-written report as finalized."""
+    from lib_py.loop import finalize
+
+    path = _report(tmp_path, "final body\n", staged=True)
+    assert not path.exists() and path.with_name(path.name + ".tmp").exists()
+    manifest = finalize.finalize_report(path, "job1", 1)
+    assert path.exists() and not path.with_name(path.name + ".tmp").exists()
+    assert manifest["sha256"] == finalize.sha256_of(path)
+
+
+def test_finalize_verifies_against_the_file_not_the_declaration(tmp_path):
+    """The hash is recomputed, so a forged manifest cannot certify itself."""
+    from lib_py.loop import finalize
+
+    path = _report(tmp_path)
+    finalize.finalize_report(path, "job1", 1)
+    assert finalize.verify_manifest(path.parent, "job1").ok
+
+    manifest_file = finalize.manifest_in(path.parent)
+    forged = json.loads(manifest_file.read_text(encoding="utf-8"))
+    forged["sha256"] = "0" * 64
+    manifest_file.write_text(json.dumps(forged), encoding="utf-8")
+    verdict = finalize.verify_manifest(path.parent, "job1")
+    assert not verdict.ok and "changed after finalization" in verdict.reason
+
+
+def test_finalize_is_invalidated_by_a_rewritten_report(tmp_path):
+    """A new body needs a new finalization; the old hash is void immediately."""
+    from lib_py.loop import finalize
+
+    path = _report(tmp_path, "first\n")
+    finalize.finalize_report(path, "job1", 1)
+    assert finalize.verify_manifest(path.parent, "job1").ok
+    path.write_text("rewritten\n", encoding="utf-8")
+    verdict = finalize.verify_manifest(path.parent, "job1")
+    assert not verdict.ok and "changed after finalization" in verdict.reason
+
+
+@pytest.mark.parametrize("kwargs,fragment", [
+    ({"job_id": "other"}, "belongs to job"),
+    ({"expected_attempt": 9}, "belongs to attempt"),
+])
+def test_finalize_rejects_a_manifest_for_a_different_job_or_attempt(tmp_path, kwargs, fragment):
+    from lib_py.loop import finalize
+    path = _report(tmp_path)
+    finalize.finalize_report(path, "job1", 1)
+    args = {"job_id": "job1"}
+    args.update(kwargs)
+    verdict = finalize.verify_manifest(path.parent, **args)
+    assert not verdict.ok and fragment in verdict.reason
+
+
+def test_finalize_requires_evidence_for_every_declared_side_effect(tmp_path):
+    """Partial evidence is no evidence: the work is not known to be complete."""
+    from lib_py.loop import finalize
+
+    path = _report(tmp_path)
+    finalize.finalize_report(path, "job1", 1,
+                             side_effects=finalize.parse_side_effects(["git_push=abc123"]))
+    ok = finalize.verify_manifest(path.parent, "job1", expected_artifacts=["git_push"])
+    assert ok.ok
+    missing = finalize.verify_manifest(path.parent, "job1",
+                                       expected_artifacts=["git_push", "api_call"])
+    assert not missing.ok and "api_call" in missing.reason
+
+
+def test_finalize_rejects_a_malformed_side_effect_pair():
+    from lib_py.loop import finalize
+    with pytest.raises(ValueError):
+        finalize.parse_side_effects(["nokey"])
+    with pytest.raises(ValueError):
+        finalize.parse_side_effects(["kind="])
+
+
+def test_finalize_missing_manifest_is_a_refusal_not_a_crash(tmp_path):
+    from lib_py.loop import finalize
+    d = tmp_path / "empty"
+    d.mkdir()
+    verdict = finalize.verify_manifest(d, "job1")
+    assert not verdict.ok and "no completion manifest" in verdict.reason
+
+
+def test_publish_event_finalizes_before_it_publishes(mam_sandbox, tmp_path, monkeypatch):
+    """The CLI surface an agent actually calls."""
+    monkeypatch.chdir(mam_sandbox)
+    from lib_py.delegation import publish_event
+    from lib_py.loop import finalize
+
+    reg = _reg(tmp_path)
+    job_id = _make_job(reg)
+    record = _load(reg, job_id)
+    record["broker"] = {"host": "127.0.0.1", "port": 65432, "tls": False}
+    Path(reg, job_id + ".json").write_text(json.dumps(record), encoding="utf-8")
+
+    path = _report(tmp_path, "the report\n", staged=True)
+    rc = publish_event.main([
+        "--registry-dir", reg, "--job", job_id, "--event", "completed",
+        "--attempts", "1", "--finalize-report", str(path),
+        "--side-effect", "git_push=deadbeef",
+    ])
+    assert rc == 2, "the broker is unreachable, but finalization still happened"
+    assert path.exists(), "the staged report was promoted"
+    verdict = finalize.verify_manifest(path.parent, job_id)
+    assert verdict.ok
+    assert verdict.manifest["side_effects"][0]["kind"] == "git_push"
+
+
+def test_publish_event_reports_a_bad_side_effect_instead_of_publishing(mam_sandbox, tmp_path, monkeypatch):
+    monkeypatch.chdir(mam_sandbox)
+    from lib_py.delegation import publish_event
+    reg = _reg(tmp_path)
+    job_id = _make_job(reg)
+    path = _report(tmp_path)
+    rc = publish_event.main([
+        "--registry-dir", reg, "--job", job_id, "--event", "completed",
+        "--finalize-report", str(path), "--side-effect", "malformed",
+    ])
+    assert rc == 1