diff --git a/canonical_thread_handoff.py b/canonical_thread_handoff.py
index aa0a85b..6d262c2 100644
--- a/canonical_thread_handoff.py
+++ b/canonical_thread_handoff.py
@@ -46,6 +46,17 @@ _FIELD_RE = re.compile(
 )
 
 
+def is_known_cth_type(value: str | None) -> bool:
+    """True when *value* is a declared member of the :data:`CTH_TYPES` contract.
+
+    ``CTH_TYPES`` is the single authority for what a CTH type may be. The
+    heading a comment carries is free text, so a *read* path that turns a parsed
+    type into something durable — a serialized field, a routing decision — must
+    check membership here rather than trust the parse or keep a list of its own.
+    """
+    return (value or "").strip() in CTH_TYPES
+
+
 def format_cth_body(
     *,
     cth_type: str,
@@ -60,7 +71,7 @@ def format_cth_body(
 ) -> str:
     """Render a canonical CTH comment body."""
     normalized_type = (cth_type or "").strip()
-    if normalized_type not in CTH_TYPES:
+    if not is_known_cth_type(normalized_type):
         raise ValueError(
             f"unknown CTH type '{cth_type}'; expected one of {sorted(CTH_TYPES)}"
         )
@@ -101,6 +112,12 @@ def parse_cth_comment(body: str) -> dict[str, Any] | None:
         fields[key] = match.group(2).strip()
     return {
         "cth_type": cth_type,
+        # The heading capture is unconstrained free text, so the parse states
+        # whether it satisfies the CTH_TYPES contract instead of leaving every
+        # reader to decide (or forget). Parsing stays total — an unknown type is
+        # still parsed and reported, never raised on — but a reader that turns
+        # the type into a durable value can now tell the two apart.
+        "cth_type_known": is_known_cth_type(cth_type),
         "fields": fields,
         "raw_body": text,
     }
@@ -119,7 +136,7 @@ def assess_cth_comment(body: str) -> dict[str, Any]:
         }
 
     cth_type = parsed.get("cth_type") or ""
-    if cth_type not in CTH_TYPES:
+    if not is_known_cth_type(cth_type):
         reasons.append(
             f"unknown CTH type '{cth_type}'; expected one of {sorted(CTH_TYPES)}"
         )
diff --git a/tests/test_webui_timeline.py b/tests/test_webui_timeline.py
index 2464e74..39c7ea5 100644
--- a/tests/test_webui_timeline.py
+++ b/tests/test_webui_timeline.py
@@ -16,7 +16,13 @@ sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
 from starlette.testclient import TestClient
 
 import control_plane_db
-from canonical_thread_handoff import format_cth_body
+from canonical_thread_handoff import (
+    CTH_TYPES,
+    MARKER,
+    format_cth_body,
+    is_known_cth_type,
+    parse_cth_comment,
+)
 from webui import timeline
 from webui.app import create_app
 
@@ -614,5 +620,402 @@ class TestTimelineApi(unittest.TestCase):
         self.assertIsNone(body["error"])
 
 
+def _seed_event(path: str, *, event_type: str, message: str, created_at: str) -> None:
+    """Append one control-plane event with a caller-chosen ``event_type``.
+
+    The ``events`` table stores whatever a producer writes, so this seeds the
+    adapter the way a hostile or buggy producer would.
+    """
+    conn = sqlite3.connect(path)
+    try:
+        wid = conn.execute(
+            "SELECT work_item_id FROM work_items WHERE kind='issue' AND number=637"
+        ).fetchone()[0]
+        conn.execute(
+            "INSERT INTO events(work_item_id, event_type, message, created_at) VALUES (?,?,?,?)",
+            (wid, event_type, message, created_at),
+        )
+        conn.commit()
+    finally:
+        conn.close()
+
+
+def _raw_cth_body(heading: str, **fields) -> str:
+    """Build a CTH comment with an arbitrary heading.
+
+    ``format_cth_body`` refuses an undeclared type, which is exactly the write
+    path already covered. The read path must cope with a body that never went
+    through it, so this writes the marker and heading directly.
+    """
+    lines = [MARKER, f"## CTH: {heading}", ""]
+    base = {
+        "Status": "ready",
+        "Next owner": "reviewer",
+        "Current blocker": "none",
+        "Decision": "d",
+        "Proof": "none",
+        "Next action": "review",
+        "Ready-to-paste prompt": "Review PR #1 now",
+    }
+    base.update(fields)
+    lines.extend(f"{key}: {value}" for key, value in base.items())
+    return "\n".join(lines)
+
+
+class TestEventTypeBoundary(unittest.TestCase):
+    """F2 residual: event_type must cross the same boundary as every other field.
+
+    The canary is seeded through ``event_type`` *only*, with a benign message,
+    so message redaction cannot be what makes these pass. Each case inspects
+    ``event_type`` explicitly and then the complete serialized payload.
+    """
+
+    # ---- control-plane stored event_type ---------------------------------- #
+
+    def test_cp_event_type_canary_never_serialized(self):
+        rows = [{
+            "event_id": 1,
+            "event_type": SYNTHETIC_SECRET_40_HEX,
+            "message": "deploy completed",   # benign: no redaction happens here
+            "created_at": "2026-07-23T01:00:00Z",
+            "kind": "issue",
+            "number": 637,
+        }]
+        events = timeline.adapt_cp_events(rows)
+        self.assertEqual(len(events), 1)
+        ev = events[0]
+        # The field itself, inspected directly.
+        self.assertNotIn(SYNTHETIC_SECRET_40_HEX, ev.event_type)
+        self.assertEqual(ev.event_type, timeline.UNSAFE_EVENT_TYPE)
+        # Message redaction is provably not what saved us: it is untouched.
+        self.assertEqual(ev.message, "deploy completed")
+        # And nowhere in the serialized record.
+        self.assertNotIn(SYNTHETIC_SECRET_40_HEX, json.dumps(ev.to_dict()))
+        # An unsafe value is a visible fact, not a silent substitution.
+        self.assertTrue(ev.sensitive)
+
+    def test_cp_same_canary_in_message_and_event_type(self):
+        """The decisive case: one record, one value, two fields, one verdict."""
+        rows = [{
+            "event_id": 2,
+            "event_type": SYNTHETIC_SECRET_40_HEX,
+            "message": f"deploy token={SYNTHETIC_SECRET_40_HEX}",
+            "created_at": "2026-07-23T01:00:00Z",
+            "kind": "issue",
+            "number": 637,
+        }]
+        ev = timeline.adapt_cp_events(rows)[0]
+        self.assertNotIn(SYNTHETIC_SECRET_40_HEX, ev.message or "")
+        self.assertNotIn(SYNTHETIC_SECRET_40_HEX, ev.event_type)
+        self.assertNotIn(SYNTHETIC_SECRET_40_HEX, json.dumps(ev.to_dict()))
+
+    def test_cp_unsafe_event_type_is_not_rewritten_as_a_valid_one(self):
+        """A refused value must not be disguised as some other real event type."""
+        rows = [{
+            "event_id": 3,
+            "event_type": SYNTHETIC_SECRET_40_HEX,
+            "message": "m",
+            "created_at": "2026-07-23T01:00:00Z",
+            "kind": "issue",
+            "number": 637,
+        }]
+        ev = timeline.adapt_cp_events(rows)[0]
+        for legitimate in ("allocation", "pr.opened", "lease.renew", "assigned"):
+            self.assertNotEqual(ev.event_type, legitimate)
+
+    def test_cp_assigned_secret_in_event_type_refused(self):
+        rows = [{
+            "event_id": 4,
+            "event_type": f"token={SYNTHETIC_SECRET_40_HEX}",
+            "message": "m",
+            "created_at": "2026-07-23T01:00:00Z",
+            "kind": "issue",
+            "number": 637,
+        }]
+        ev = timeline.adapt_cp_events(rows)[0]
+        self.assertEqual(ev.event_type, timeline.UNSAFE_EVENT_TYPE)
+        self.assertNotIn(SYNTHETIC_SECRET_40_HEX, json.dumps(ev.to_dict()))
+
+    def test_cp_legitimate_event_types_preserved(self):
+        """Every real producer type in this repo must survive untouched."""
+        legitimate = [
+            "allocation", "pr.opened", "lease.renew", "assigned",
+            "lease_released", "lease_expired", "lease_abandoned",
+            "lease_adopted", "dependency_edge_state_change",
+        ]
+        rows = [
+            {
+                "event_id": i,
+                "event_type": name,
+                "message": "m",
+                "created_at": "2026-07-23T01:00:00Z",
+                "kind": "issue",
+                "number": 637,
+            }
+            for i, name in enumerate(legitimate, start=1)
+        ]
+        events = timeline.adapt_cp_events(rows)
+        self.assertEqual([e.event_type for e in events], legitimate)
+
+    def test_cp_malformed_event_type_shapes_refused(self):
+        for bad in ("has space", "1leading-digit", "x" * 200, "semi;colon", "new\nline"):
+            with self.subTest(event_type=bad):
+                rows = [{
+                    "event_id": 1,
+                    "event_type": bad,
+                    "message": "m",
+                    "created_at": "2026-07-23T01:00:00Z",
+                    "kind": "issue",
+                    "number": 637,
+                }]
+                events = timeline.adapt_cp_events(rows)
+                self.assertEqual(events[0].event_type, timeline.UNSAFE_EVENT_TYPE)
+                self.assertNotIn(bad, json.dumps(events[0].to_dict()))
+
+    # ---- CTH heading event_type ------------------------------------------- #
+
+    def test_cth_heading_canary_never_serialized(self):
+        comments = [{
+            "id": 11,
+            "body": _raw_cth_body(SYNTHETIC_SECRET_40_HEX),
+            "created_at": "2026-07-23T05:00:00Z",
+            "user": {"login": "jcwalker3"},
+        }]
+        events = timeline.adapt_cth_comments(comments, kind="issue", number=637)
+        self.assertEqual(len(events), 1)
+        ev = events[0]
+        self.assertNotIn(SYNTHETIC_SECRET_40_HEX, ev.event_type)
+        self.assertEqual(ev.event_type, timeline.UNKNOWN_HANDOFF_EVENT_TYPE)
+        # No message redaction is doing the work here — the message is benign.
+        self.assertEqual(ev.message, "review")
+        self.assertNotIn(SYNTHETIC_SECRET_40_HEX, json.dumps(ev.to_dict()))
+        self.assertTrue(ev.sensitive)
+
+    def test_cth_assigned_secret_heading_refused(self):
+        comments = [{
+            "id": 12,
+            "body": _raw_cth_body(f"token={SYNTHETIC_SECRET_40_HEX}"),
+            "created_at": "2026-07-23T05:00:00Z",
+            "user": {"login": "jcwalker3"},
+        }]
+        ev = timeline.adapt_cth_comments(comments, kind="issue", number=637)[0]
+        self.assertEqual(ev.event_type, timeline.UNKNOWN_HANDOFF_EVENT_TYPE)
+        self.assertNotIn(SYNTHETIC_SECRET_40_HEX, json.dumps(ev.to_dict()))
+
+    def test_cth_unknown_and_whitespace_headings_normalized(self):
+        for heading in ("Totally Made Up", "Author  Handoff", "author handoff"):
+            with self.subTest(heading=heading):
+                comments = [{
+                    "id": 13,
+                    "body": _raw_cth_body(heading),
+                    "created_at": "2026-07-23T05:00:00Z",
+                    "user": {"login": "x"},
+                }]
+                events = timeline.adapt_cth_comments(comments, kind="issue", number=637)
+                self.assertEqual(len(events), 1)
+                self.assertEqual(events[0].event_type, timeline.UNKNOWN_HANDOFF_EVENT_TYPE)
+
+    def test_cth_declared_types_all_preserved(self):
+        """Point 5: no legitimate declared type is lost to the new check."""
+        for cth_type in sorted(CTH_TYPES):
+            with self.subTest(cth_type=cth_type):
+                comments = [{
+                    "id": 14,
+                    "body": _raw_cth_body(cth_type),
+                    "created_at": "2026-07-23T05:00:00Z",
+                    "user": {"login": "x"},
+                }]
+                ev = timeline.adapt_cth_comments(comments, kind="issue", number=637)[0]
+                self.assertEqual(ev.event_type, f"handoff:{cth_type}")
+                self.assertFalse(ev.sensitive)
+
+    def test_cth_surrounding_whitespace_still_matches_contract(self):
+        comments = [{
+            "id": 15,
+            "body": _raw_cth_body("   Author Handoff   "),
+            "created_at": "2026-07-23T05:00:00Z",
+            "user": {"login": "x"},
+        }]
+        ev = timeline.adapt_cth_comments(comments, kind="issue", number=637)[0]
+        self.assertEqual(ev.event_type, "handoff:Author Handoff")
+
+    # ---- complete serialized payload, both paths -------------------------- #
+
+    def _payload_clean(self, snapshot):
+        payload = json.dumps(snapshot.to_dict())
+        self.assertNotIn(SYNTHETIC_SECRET_40_HEX, payload)
+        from webui import console_redaction
+
+        self.assertEqual(console_redaction.scan_for_secrets(snapshot.to_dict()), [])
+        return snapshot.to_dict()
+
+    def test_canary_absent_from_full_payload_via_cp_event_type(self):
+        import tempfile
+
+        with tempfile.TemporaryDirectory() as tmp:
+            db = os.path.join(tmp, "cp.sqlite3")
+            _seed_db(db)
+            _seed_event(
+                db,
+                event_type=SYNTHETIC_SECRET_40_HEX,
+                message="routine deploy",
+                created_at="2026-07-23T06:00:00Z",
+            )
+            snap = timeline.load_timeline(
+                remote="prgs", org="Scaled-Tech-Consulting", repo="Gitea-Tools",
+                issue=637, db_path=db, comment_source=lambda k, n: [],
+            )
+            d = self._payload_clean(snap)
+            types = [e["event_type"] for e in d["events"]]
+            self.assertIn(timeline.UNSAFE_EVENT_TYPE, types)
+            # The legitimate seeded types are still present and unchanged.
+            self.assertIn("allocation", types)
+
+    def test_canary_absent_from_full_payload_via_cth_heading(self):
+        import tempfile
+
+        comments = [{
+            "id": 21,
+            "body": _raw_cth_body(SYNTHETIC_SECRET_40_HEX),
+            "created_at": "2026-07-23T09:00:00Z",
+            "user": {"login": "jcwalker3"},
+        }]
+        with tempfile.TemporaryDirectory() as tmp:
+            db = os.path.join(tmp, "cp.sqlite3")
+            _seed_db(db)
+            snap = timeline.load_timeline(
+                remote="prgs", org="Scaled-Tech-Consulting", repo="Gitea-Tools",
+                issue=637, db_path=db, comment_source=lambda k, n: comments,
+            )
+            d = self._payload_clean(snap)
+            self.assertIn(
+                timeline.UNKNOWN_HANDOFF_EVENT_TYPE,
+                [e["event_type"] for e in d["events"]],
+            )
+
+    def test_canary_absent_when_seeded_through_both_paths_at_once(self):
+        import tempfile
+
+        comments = [{
+            "id": 22,
+            "body": _raw_cth_body(SYNTHETIC_SECRET_40_HEX),
+            "created_at": "2026-07-23T09:00:00Z",
+            "user": {"login": "jcwalker3"},
+        }]
+        with tempfile.TemporaryDirectory() as tmp:
+            db = os.path.join(tmp, "cp.sqlite3")
+            _seed_db(db)
+            _seed_event(
+                db,
+                event_type=SYNTHETIC_SECRET_40_HEX,
+                message=f"deploy token={SYNTHETIC_SECRET_40_HEX}",
+                created_at="2026-07-23T06:00:00Z",
+            )
+            snap = timeline.load_timeline(
+                remote="prgs", org="Scaled-Tech-Consulting", repo="Gitea-Tools",
+                issue=637, db_path=db, comment_source=lambda k, n: comments,
+            )
+            self._payload_clean(snap)
+
+
+class TestSerializedFieldAudit(unittest.TestCase):
+    """The remaining externally influenced strings that reach the payload."""
+
+    def test_event_key_ids_must_be_plain_identifiers(self):
+        rows = [
+            {"event_id": SYNTHETIC_SECRET_40_HEX, "event_type": "allocation",
+             "message": "m", "created_at": "2026-07-23T01:00:00Z",
+             "kind": "issue", "number": 637},
+            {"event_id": 8, "event_type": "allocation", "message": "m",
+             "created_at": "2026-07-23T01:00:00Z", "kind": "issue", "number": 637},
+        ]
+        events = timeline.adapt_cp_events(rows)
+        self.assertEqual([e.event_key for e in events], ["cp:8"])
+
+    def test_comment_id_must_be_a_plain_identifier(self):
+        comments = [{
+            "id": SYNTHETIC_SECRET_40_HEX,
+            "body": _raw_cth_body("Author Handoff"),
+            "created_at": "2026-07-23T05:00:00Z",
+            "user": {"login": "x"},
+        }]
+        self.assertEqual(timeline.adapt_cth_comments(comments, kind="issue", number=637), [])
+
+    def test_adapter_refuses_a_scope_it_cannot_express(self):
+        comments = [{
+            "id": 1,
+            "body": _raw_cth_body("Author Handoff"),
+            "created_at": "2026-07-23T05:00:00Z",
+            "user": {"login": "x"},
+        }]
+        self.assertEqual(
+            timeline.adapt_cth_comments(comments, kind="issue", number=SYNTHETIC_SECRET_40_HEX),
+            [],
+        )
+        self.assertEqual(
+            timeline.adapt_cth_comments(comments, kind=SYNTHETIC_SECRET_40_HEX, number=1),
+            [],
+        )
+
+    def test_source_failure_reason_is_redacted(self):
+        def boom(kind, number):
+            raise RuntimeError(f"auth failed with token={SYNTHETIC_SECRET_40_HEX}")
+
+        import tempfile
+
+        with tempfile.TemporaryDirectory() as tmp:
+            db = os.path.join(tmp, "cp.sqlite3")
+            _seed_db(db)
+            snap = timeline.load_timeline(
+                remote="prgs", org="Scaled-Tech-Consulting", repo="Gitea-Tools",
+                issue=637, db_path=db, comment_source=boom,
+            )
+            d = snap.to_dict()
+            handoff = [s for s in d["sources"] if s["name"] == "gitea_handoff"][0]
+            self.assertFalse(handoff["ok"])
+            self.assertIn("handoff source failed", handoff["reason"])
+            self.assertNotIn(SYNTHETIC_SECRET_40_HEX, json.dumps(d))
+
+    def test_echoed_scope_and_filters_are_guarded(self):
+        import tempfile
+
+        with tempfile.TemporaryDirectory() as tmp:
+            db = os.path.join(tmp, "cp.sqlite3")
+            _seed_db(db)
+            d = timeline.load_timeline(
+                remote="prgs", org="Scaled-Tech-Consulting", repo="Gitea-Tools",
+                issue=637, session=SYNTHETIC_SECRET_40_HEX, db_path=db,
+                comment_source=lambda k, n: [],
+            ).to_dict()
+            self.assertNotIn(SYNTHETIC_SECRET_40_HEX, json.dumps(d))
+            # Ordinary scope values are untouched, so the echo stays useful.
+            self.assertEqual(
+                d["scope"],
+                {"remote": "prgs", "org": "Scaled-Tech-Consulting", "repo": "Gitea-Tools"},
+            )
+            self.assertEqual(d["filters"]["issue"], 637)
+
+
+class TestCthTypeContract(unittest.TestCase):
+    """The contract has one authority; the read path consults it."""
+
+    def test_declared_types_are_known(self):
+        for cth_type in CTH_TYPES:
+            self.assertTrue(is_known_cth_type(cth_type))
+
+    def test_undeclared_types_are_not_known(self):
+        for value in ("", None, "Made Up", SYNTHETIC_SECRET_40_HEX, "author handoff"):
+            self.assertFalse(is_known_cth_type(value))
+
+    def test_parse_reports_contract_membership(self):
+        known = parse_cth_comment(_raw_cth_body("Author Handoff"))
+        self.assertTrue(known["cth_type_known"])
+        self.assertEqual(known["cth_type"], "Author Handoff")
+        unknown = parse_cth_comment(_raw_cth_body("Not A Real Type"))
+        # Parsing stays total: the type is still reported, just not endorsed.
+        self.assertEqual(unknown["cth_type"], "Not A Real Type")
+        self.assertFalse(unknown["cth_type_known"])
+
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/webui/timeline.py b/webui/timeline.py
index ded93c8..1ec8284 100644
--- a/webui/timeline.py
+++ b/webui/timeline.py
@@ -203,6 +203,28 @@ _REF_SHA_SHAPE = re.compile(r"^[0-9a-f]{7,40}$")
 # material wherever it appears, never as an identifier.
 _BARE_SECRET_SHAPE = re.compile(r"^[0-9a-f]{32,}$")
 
+# An event type reads like an identifier, but a stored one is externally
+# influenced: any producer that writes the control-plane ``events`` table
+# chooses the string. It reaches ``to_dict`` verbatim, so it is validated here
+# rather than trusted because of where it came from.
+_CP_EVENT_TYPE_SHAPE = re.compile(r"^[A-Za-z][A-Za-z0-9._:+-]{0,63}$")
+
+# Emitted in place of a value that cannot be proven safe. Deliberately not a
+# plausible workflow type: an unsafe value is refused, never quietly rewritten
+# into a different valid-looking one that would misdescribe the record.
+UNSAFE_EVENT_TYPE = "unsafe:redacted"
+
+# Emitted for a CTH heading that is not a declared member of ``CTH_TYPES``. The
+# contract is enforced on write (``format_cth_body``) and on assess; the read
+# path the timeline uses enforces it too rather than assuming it was.
+UNKNOWN_HANDOFF_EVENT_TYPE = "handoff:unrecognized"
+
+# A source record id is a plain integer in both sources it comes from: the
+# control-plane ``events`` primary key and a Gitea comment id. ``event_key`` is
+# serialized verbatim and is the pagination tiebreak, so anything else is
+# refused rather than interpolated into it.
+_RECORD_ID_SHAPE = re.compile(r"^[0-9]{1,19}$")
+
 
 def _kind_to_numbers(kind: str | None, number: int | None) -> tuple[int | None, int | None]:
     """Map a control-plane work-item (kind, number) to (issue_no, pr_no)."""
@@ -297,6 +319,64 @@ def _safe_session_id(value: Any) -> str | None:
     return text if _redact(text) == text else None
 
 
+def _safe_record_id(value: Any) -> str | None:
+    """Return a source record id only when it is a plain numeric identifier.
+
+    ``event_key`` is serialized verbatim and is the deterministic pagination
+    tiebreak, so an id is interpolated into it only when it has the shape both
+    real sources actually produce. A record whose identity cannot be trusted is
+    refused by the caller rather than keyed on.
+    """
+    if value is None or isinstance(value, bool):
+        return None
+    if isinstance(value, int):
+        return str(value)
+    text = str(value).strip()
+    return text if _RECORD_ID_SHAPE.match(text) else None
+
+
+def _safe_cp_event_type(value: Any) -> tuple[str, bool]:
+    """Validate a stored control-plane event type. Returns ``(type, unsafe)``.
+
+    The stored value is externally influenced — whichever producer wrote the
+    ``events`` row chose the string — and ``to_dict`` serializes it verbatim, so
+    it passes a boundary of its own instead of relying on the one ``message``
+    passes. A value survives only when it is an ordinary identifier, is not a
+    bare secret-shaped hex run, and is unchanged by a redaction pass. Anything
+    else fails closed to :data:`UNSAFE_EVENT_TYPE`: the record stays visible as
+    an audit entry, but the value itself is never republished — not verbatim,
+    not partially sanitized, and not rewritten into some other valid-looking
+    type that would misdescribe what happened.
+    """
+    text = ("" if value is None else str(value)).strip()
+    if not text:
+        return ("", False)
+    if _BARE_SECRET_SHAPE.match(text):
+        return (UNSAFE_EVENT_TYPE, True)
+    if not _CP_EVENT_TYPE_SHAPE.match(text):
+        return (UNSAFE_EVENT_TYPE, True)
+    if _redact(text) != text:
+        return (UNSAFE_EVENT_TYPE, True)
+    return (text, False)
+
+
+def _safe_echo(value: Any) -> Any:
+    """Guard a scalar that is echoed back rather than derived from a record.
+
+    Query scope and filter values are caller-supplied and are reflected in the
+    response so an operator can see what was asked. Reflection is still
+    emission: a value redaction would alter, or a bare secret-shaped hex run, is
+    replaced by the placeholder instead of being echoed verbatim. Ordinary
+    scope and filter values pass through untouched.
+    """
+    if value is None or isinstance(value, (int, bool)):
+        return value
+    text = str(value)
+    if _BARE_SECRET_SHAPE.match(text.strip()):
+        return console_redaction.REDACTED
+    return _redact(text)
+
+
 def adapt_cp_events(rows: Iterable[dict[str, Any]]) -> list[WorkflowEvent]:
     """Adapt control-plane ``events`` rows (joined to work_items) into events.
 
@@ -307,14 +387,20 @@ def adapt_cp_events(rows: Iterable[dict[str, Any]]) -> list[WorkflowEvent]:
     events: list[WorkflowEvent] = []
     for row in rows or []:
         try:
-            event_id = row.get("event_id")
-            event_type = (row.get("event_type") or "").strip()
-            if event_id is None or not event_type:
+            event_id = _safe_record_id(row.get("event_id"))
+            raw_event_type = (row.get("event_type") or "").strip()
+            if event_id is None or not raw_event_type:
                 continue
+            # The stored type is source data, not a trusted constant: validate
+            # it before it is serialized, exactly as `message` below is redacted
+            # before it is serialized.
+            event_type, event_type_unsafe = _safe_cp_event_type(raw_event_type)
             kind = row.get("kind")
             number = row.get("number")
             issue_no, pr_no = _kind_to_numbers(kind, number)
-            sensitive = any(hint in event_type.lower() for hint in _SENSITIVE_EVENT_HINTS)
+            sensitive = event_type_unsafe or any(
+                hint in raw_event_type.lower() for hint in _SENSITIVE_EVENT_HINTS
+            )
             events.append(
                 WorkflowEvent(
                     source=SOURCE_CONTROL_PLANE,
@@ -355,7 +441,18 @@ def adapt_cth_comments(
     """
     # Imported lazily so this module has no import-time dependency on the
     # handoff parser when only the control-plane adapter is used.
-    from canonical_thread_handoff import parse_cth_comment
+    from canonical_thread_handoff import is_known_cth_type, parse_cth_comment
+
+    # ``kind``/``number`` are interpolated into event_key and correlation_id, so
+    # they are normalised once here. A scope this adapter cannot express is
+    # refused outright rather than serialized into an identifier.
+    kind = (kind or "").strip().lower()
+    if kind not in ("issue", "pr"):
+        return []
+    try:
+        number = int(number)
+    except (TypeError, ValueError):
+        return []
 
     issue_no, pr_no = _kind_to_numbers(kind, number)
     correlation = _correlation_for(kind, number)
@@ -367,8 +464,17 @@ def adapt_cth_comments(
             if not parsed:
                 continue
             fields = parsed.get("fields") or {}
-            cth_type = parsed.get("cth_type") or "handoff"
-            comment_id = comment.get("id")
+            cth_type = parsed.get("cth_type") or ""
+            comment_id = _safe_record_id(comment.get("id"))
+            if comment_id is None:
+                continue
+            # The CTH heading is free text: the parser accepts whatever follows
+            # "## CTH:", and only the write and assess paths check it against
+            # the contract. Check it here too — an unrecognised heading is
+            # reported as such rather than serialized into event_type, so
+            # arbitrary, malformed, or secret-shaped heading content has no way
+            # through. Declared types are preserved exactly.
+            cth_type_known = is_known_cth_type(cth_type)
             # Redaction runs first, and every derived value is taken from the
             # redacted text — deriving evidence refs from the raw proof would
             # re-emit exactly what redaction was about to remove.
@@ -381,7 +487,11 @@ def adapt_cth_comments(
             events.append(
                 WorkflowEvent(
                     source=SOURCE_GITEA_HANDOFF,
-                    event_type=f"handoff:{cth_type}",
+                    event_type=(
+                        f"handoff:{cth_type.strip()}"
+                        if cth_type_known
+                        else UNKNOWN_HANDOFF_EVENT_TYPE
+                    ),
                     event_key=f"cth:{kind}:{number}:{comment_id}",
                     timestamp=_parse_ts(comment.get("created_at")),
                     actor=_redact((comment.get("user") or {}).get("login")),
@@ -396,7 +506,7 @@ def adapt_cth_comments(
                     message=next_action or _redact(fields.get("status")),
                     correlation_id=correlation,
                     evidence_refs=refs,
-                    sensitive=refs_dropped,
+                    sensitive=refs_dropped or not cth_type_known,
                 )
             )
         except Exception:
@@ -453,7 +563,10 @@ def _cp_status(*, ok: bool, reason: str | None = None, count: int = 0) -> Source
     return SourceStatus(
         SOURCE_CONTROL_PLANE,
         ok=ok,
-        reason=reason,
+        # A failure reason is serialized like any other field and is often an
+        # exception string carrying a path or a transport error, so it crosses
+        # the redaction boundary too. Static reasons pass through unchanged.
+        reason=_redact(reason),
         count=count,
         supported_filters=_SOURCE_FILTER_SUPPORT[SOURCE_CONTROL_PLANE],
     )
@@ -463,7 +576,9 @@ def _handoff_status(*, ok: bool, reason: str | None = None, count: int = 0) -> S
     return SourceStatus(
         SOURCE_GITEA_HANDOFF,
         ok=ok,
-        reason=reason,
+        # Same boundary as the control-plane status: this reason can quote an
+        # error raised by a live authenticated fetch.
+        reason=_redact(reason),
         count=count,
         supported_filters=_SOURCE_FILTER_SUPPORT[SOURCE_GITEA_HANDOFF],
     )
@@ -623,8 +738,15 @@ class TimelineSnapshot:
             "ok": self.ok,
             "error": self.error,
             "schema_version": self.schema_version,
-            "scope": {"remote": self.remote, "org": self.org, "repo": self.repo},
-            "filters": self.filters,
+            # Scope and filters are echoed caller input, not derived record
+            # data. Reflecting a value is still emitting it, so both cross the
+            # same boundary; ordinary scope and filter values are unchanged.
+            "scope": {
+                "remote": _safe_echo(self.remote),
+                "org": _safe_echo(self.org),
+                "repo": _safe_echo(self.repo),
+            },
+            "filters": {key: _safe_echo(value) for key, value in self.filters.items()},
             "sources": [s.to_dict() for s in self.sources],
             **self.page.to_dict(),
         }