feat(prober,correlation): attacker fingerprint rotation detection (DEBT-032)

When the prober observes a NEW hash for an
(attacker_uuid, port, probe_type) triple it has seen before — VPS
rotation, SSH server rebuild, TLS cert swap — emit a derived
attacker.fingerprint_rotated event carrying both old and new hash.
Detection is a small library (decnet.correlation.fingerprint_rotation)
called inline from the prober at each of the three emit sites
(JARM/HASSH/TCPFP). No new daemon. New AttackerFingerprintState table
holds per-triple last-hash state; Attacker.rotation_count and
Attacker.last_rotation_at are stamped on every diff. Library is sync,
fully unit-tested via injected publish_fn / syslog_fn callbacks.

decnet/bus/topics.py

@@ -114,6 +114,14 @@ ATTACKER_SCORED = "scored"
 # Distinct from ``observed`` which is the correlator's first-sight signal —
 # a fingerprint is additional evidence about an already-observed attacker.
 ATTACKER_FINGERPRINTED = "fingerprinted"
+# Published when the prober observes a NEW hash for an
+# (attacker_ip, port, probe_type) triple it has seen before — i.e. the
+# attacker rotated their VPS, rebuilt their SSH server, swapped their
+# TLS cert.  Distinct from ``fingerprinted`` which fires on every probe
+# result; ``fingerprint_rotated`` fires only on diff and carries both
+# old_hash + new_hash.  Producer: prober (via the rotation library);
+# consumers: dashboard, forensics, attribution clustering.
+ATTACKER_FINGERPRINT_ROTATED = "fingerprint_rotated"
 ATTACKER_SESSION_STARTED = "session.started"
 ATTACKER_SESSION_ENDED = "session.ended"
 # Published by the ``decnet enrich`` worker after an enrichment pass

decnet/correlation/fingerprint_rotation.py

@@ -0,0 +1,153 @@
+"""Attacker substrate-fingerprint rotation detection.
+
+Called inline from the prober at each fingerprint emit site.  Looks up
+the last persisted hash for ``(attacker_uuid, port, probe_type)``;
+when the new hash differs from the last one, emits a derived
+``attacker.fingerprint_rotated`` event (bus + RFC 5424 syslog) and
+stamps the ``Attacker`` row's rotation telemetry.
+
+This is a pure library — no daemon, no async loop.  The prober is the
+only producer.  We just teach it to derive a second event on hash
+flip without standing up another worker (DEBT-032).
+"""
+from __future__ import annotations
+
+import uuid as _uuid
+from dataclasses import dataclass
+from datetime import datetime
+from typing import Any, Callable, Literal
+
+from sqlmodel import Session, select
+
+from decnet.web.db.models import Attacker, AttackerFingerprintState
+
+ProbeType = Literal["jarm", "hassh", "tcpfp"]
+RotationKind = Literal[
+    "no_attacker_row",  # caller raced ahead of correlator; skip silently
+    "first_sighting",   # state row created, no prior hash
+    "unchanged",        # same hash as last sighting
+    "rotated",          # hash differs; event emitted, Attacker stamped
+]
+
+PublishFn = Callable[[str, dict[str, Any]], None]
+SyslogFn = Callable[[str, dict[str, Any]], None]
+
+
+@dataclass
+class RotationOutcome:
+    """Return shape of :func:`record_fingerprint`.  Caller usually
+    ignores it; useful for tests + tracing."""
+    kind: RotationKind
+    old_hash: str | None
+    new_hash: str
+    rotation_count: int
+
+
+_ROTATED_EVENT_TYPE = "attacker.fingerprint_rotated"
+
+
+def record_fingerprint(
+    session: Session,
+    *,
+    attacker_ip: str,
+    port: int,
+    probe_type: ProbeType,
+    new_hash: str,
+    ts: datetime,
+    publish_fn: PublishFn | None = None,
+    syslog_fn: SyslogFn | None = None,
+) -> RotationOutcome:
+    """Upsert state row; on hash diff, emit derived event + stamp.
+
+    Resolves ``attacker_uuid`` from ``attacker_ip`` via the existing
+    Attacker table.  If no Attacker row exists yet (the prober raced
+    ahead of the correlator), returns ``kind="no_attacker_row"`` and
+    does nothing — the next probe cycle will pick it up once the
+    correlator has caught up.
+
+    State upsert + Attacker stamp + publish + syslog are committed in
+    one transaction so a partial failure can't desync state from
+    what was emitted.
+    """
+    attacker = session.exec(
+        select(Attacker).where(Attacker.ip == attacker_ip)
+    ).first()
+    if attacker is None:
+        return RotationOutcome(
+            kind="no_attacker_row",
+            old_hash=None,
+            new_hash=new_hash,
+            rotation_count=0,
+        )
+
+    row = session.exec(
+        select(AttackerFingerprintState).where(
+            AttackerFingerprintState.attacker_uuid == attacker.uuid,
+            AttackerFingerprintState.port == port,
+            AttackerFingerprintState.probe_type == probe_type,
+        )
+    ).first()
+
+    if row is None:
+        session.add(AttackerFingerprintState(
+            uuid=str(_uuid.uuid4()),
+            attacker_uuid=attacker.uuid,
+            port=port,
+            probe_type=probe_type,
+            last_hash=new_hash,
+            last_seen=ts,
+            rotation_count=0,
+        ))
+        session.commit()
+        return RotationOutcome(
+            kind="first_sighting",
+            old_hash=None,
+            new_hash=new_hash,
+            rotation_count=0,
+        )
+
+    if row.last_hash == new_hash:
+        row.last_seen = ts
+        session.add(row)
+        session.commit()
+        return RotationOutcome(
+            kind="unchanged",
+            old_hash=row.last_hash,
+            new_hash=new_hash,
+            rotation_count=row.rotation_count,
+        )
+
+    old_hash = row.last_hash
+    row.last_hash = new_hash
+    row.last_seen = ts
+    row.rotation_count += 1
+    session.add(row)
+
+    attacker.rotation_count += 1
+    attacker.last_rotation_at = ts
+    session.add(attacker)
+
+    payload: dict[str, Any] = {
+        "attacker_uuid": attacker.uuid,
+        "attacker_ip": attacker_ip,
+        "port": port,
+        "probe_type": probe_type,
+        "old_hash": old_hash,
+        "new_hash": new_hash,
+        "rotation_count": row.rotation_count,
+        "ts": ts.isoformat(),
+    }
+
+    if publish_fn is not None:
+        publish_fn(_ROTATED_EVENT_TYPE, payload)
+    if syslog_fn is not None:
+        syslog_fn(_ROTATED_EVENT_TYPE, payload)
+
+    session.commit()
+
+    return RotationOutcome(
+        kind="rotated",
+        old_hash=old_hash,
+        new_hash=new_hash,
+        rotation_count=row.rotation_count,
+    )

decnet/prober/worker.py

@@ -27,6 +27,9 @@ from datetime import datetime, timezone
 from pathlib import Path
 from typing import Any, Callable
 
+from sqlalchemy.engine import Engine
+from sqlmodel import Session
+
 from decnet.bus import topics as _topics
 from decnet.bus.base import BaseBus
 from decnet.bus.factory import get_bus
@@ -35,6 +38,10 @@ from decnet.bus.publish import (
     run_control_listener,
     run_health_heartbeat,
 )
+from decnet.correlation.fingerprint_rotation import (
+    ProbeType,
+    record_fingerprint,
+)
 from decnet.logging import get_logger
 from decnet.prober.hassh import hassh_server
 from decnet.prober.jarm import JARM_EMPTY_HASH, jarm_hash
@@ -44,6 +51,21 @@ from decnet.telemetry import traced as _traced
 
 logger = get_logger("prober")
 
+
+def _build_sync_engine() -> Engine:
+    """Construct a sync SQLite engine for rotation-detection state.
+
+    Used inline by the prober; it lives outside the async repository
+    layer because rotation detection is a sync hook on a sync probe
+    path.  Honors the same defaulting as
+    ``decnet.web.db.sqlite.repository.SQLiteRepository``.
+    """
+    import os
+    from decnet.config import _ROOT
+    from decnet.web.db.sqlite.database import get_sync_engine
+    db_path = os.environ.get("DECNET_DB_PATH", str(_ROOT / "decnet.db"))
+    return get_sync_engine(db_path)
+
 # ─── Default ports per probe type ───────────────────────────────────────────
 
 # JARM: common C2 callback / TLS server ports
@@ -233,6 +255,14 @@ def _discover_attackers(json_path: Path, position: int) -> tuple[set[str], int]:
 
 ProbePublishFn = Callable[[str, dict[str, Any]], None]
 
+# Rotation recorder: takes (attacker_ip, port, probe_type, new_hash) and
+# performs the rotation-detection upsert + derived-event emission for the
+# DEBT-032 substrate-fingerprint flow.  Optional; when None the prober
+# behaves exactly as before (raw fingerprint emit only, no rotation
+# detection).  Construction lives at worker startup so phase functions
+# don't have to know about the DB engine.
+RotationRecorderFn = Callable[[str, int, "ProbeType", str], None]
+
 
 @_traced("prober.probe_cycle")
 def _probe_cycle(
@@ -245,6 +275,7 @@ def _probe_cycle(
     json_path: Path,
     timeout: float = 5.0,
     publish_fn: ProbePublishFn | None = None,
+    record_rotation: RotationRecorderFn | None = None,
 ) -> None:
     """
     Probe all known attacker IPs with JARM, HASSH, and TCP/IP fingerprinting.
@@ -263,13 +294,13 @@ def _probe_cycle(
         ip_probed = probed.setdefault(ip, {})
 
         # Phase 1: JARM (TLS fingerprinting)
-        _jarm_phase(ip, ip_probed, jarm_ports, log_path, json_path, timeout, publish_fn)
+        _jarm_phase(ip, ip_probed, jarm_ports, log_path, json_path, timeout, publish_fn, record_rotation)
 
         # Phase 2: HASSHServer (SSH fingerprinting)
-        _hassh_phase(ip, ip_probed, ssh_ports, log_path, json_path, timeout, publish_fn)
+        _hassh_phase(ip, ip_probed, ssh_ports, log_path, json_path, timeout, publish_fn, record_rotation)
 
         # Phase 3: TCP/IP stack fingerprinting
-        _tcpfp_phase(ip, ip_probed, tcpfp_ports, log_path, json_path, timeout, publish_fn)
+        _tcpfp_phase(ip, ip_probed, tcpfp_ports, log_path, json_path, timeout, publish_fn, record_rotation)
 
 
 @_traced("prober.jarm_phase")
@@ -281,6 +312,7 @@ def _jarm_phase(
     json_path: Path,
     timeout: float,
     publish_fn: ProbePublishFn | None = None,
+    record_rotation: RotationRecorderFn | None = None,
 ) -> None:
     """JARM-fingerprint an IP on the given TLS ports."""
     done = ip_probed.setdefault("jarm", set())
@@ -301,6 +333,8 @@ def _jarm_phase(
                 msg=f"JARM {ip}:{port} = {h}",
             )
             logger.info("prober: JARM %s:%d = %s", ip, port, h)
+            if record_rotation is not None:
+                record_rotation(ip, port, "jarm", h)
             if publish_fn is not None:
                 publish_fn(
                     "jarm",
@@ -387,6 +421,7 @@ def _hassh_phase(
     json_path: Path,
     timeout: float,
     publish_fn: ProbePublishFn | None = None,
+    record_rotation: RotationRecorderFn | None = None,
 ) -> None:
     """HASSHServer-fingerprint an IP on the given SSH ports."""
     done = ip_probed.setdefault("hassh", set())
@@ -412,6 +447,8 @@ def _hassh_phase(
                 msg=f"HASSH {ip}:{port} = {result['hassh_server']}",
             )
             logger.info("prober: HASSH %s:%d = %s", ip, port, result["hassh_server"])
+            if record_rotation is not None:
+                record_rotation(ip, port, "hassh", result["hassh_server"])
             if publish_fn is not None:
                 publish_fn(
                     "hassh",
@@ -445,6 +482,7 @@ def _tcpfp_phase(
     json_path: Path,
     timeout: float,
     publish_fn: ProbePublishFn | None = None,
+    record_rotation: RotationRecorderFn | None = None,
 ) -> None:
     """TCP/IP stack fingerprint an IP on the given ports."""
     done = ip_probed.setdefault("tcpfp", set())
@@ -478,6 +516,8 @@ def _tcpfp_phase(
                 msg=f"TCPFP {ip}:{port} = {result['tcpfp_hash']}",
             )
             logger.info("prober: TCPFP %s:%d = %s", ip, port, result["tcpfp_hash"])
+            if record_rotation is not None:
+                record_rotation(ip, port, "tcpfp", result["tcpfp_hash"])
             if publish_fn is not None:
                 publish_fn(
                     "tcpfp",
@@ -586,6 +626,61 @@ async def prober_worker(
             event_type,
         )
 
+    # Substrate-rotation detection (DEBT-032) — open a sync engine for
+    # the prober's lifetime; recorder closes a session per call so we
+    # never hold a connection across phase boundaries.  Failure to
+    # connect is non-fatal: probes continue, rotation detection is
+    # silently disabled.
+    rotation_engine: Engine | None = None
+    record_rotation: RotationRecorderFn | None = None
+    try:
+        rotation_engine = _build_sync_engine()
+    except Exception as exc:  # noqa: BLE001
+        logger.warning(
+            "prober: rotation-detection DB unavailable, "
+            "running with rotation detection disabled: %s", exc,
+        )
+
+    if rotation_engine is not None:
+        def _publish_rotation(event_type: str, payload: dict[str, Any]) -> None:
+            raw_publish(
+                _topics.attacker(_topics.ATTACKER_FINGERPRINT_ROTATED),
+                payload,
+                event_type,
+            )
+
+        def _syslog_rotation(event_type: str, payload: dict[str, Any]) -> None:
+            _write_event(
+                log_path, json_path,
+                "fingerprint_rotated",
+                target_ip=payload["attacker_ip"],
+                target_port=str(payload["port"]),
+                probe_type=payload["probe_type"],
+                old_hash=payload.get("old_hash") or "",
+                new_hash=payload["new_hash"],
+                rotation_count=str(payload["rotation_count"]),
+                msg=(
+                    f"FP rotation {payload['attacker_ip']}:{payload['port']} "
+                    f"{payload['probe_type']} {payload.get('old_hash')} → "
+                    f"{payload['new_hash']}"
+                ),
+            )
+
+        def record_rotation(
+            ip: str, port: int, probe_type: ProbeType, new_hash: str,
+        ) -> None:
+            with Session(rotation_engine) as session:
+                record_fingerprint(
+                    session,
+                    attacker_ip=ip,
+                    port=port,
+                    probe_type=probe_type,
+                    new_hash=new_hash,
+                    ts=datetime.now(timezone.utc),
+                    publish_fn=_publish_rotation,
+                    syslog_fn=_syslog_rotation,
+                )
+
     shutdown = asyncio.Event()
     heartbeat_task = asyncio.create_task(run_health_heartbeat(bus, "prober"))
     control_task = asyncio.create_task(
@@ -612,6 +707,7 @@ async def prober_worker(
                     jarm_ports, hassh_ports, tcp_ports,
                     log_path, json_path, timeout,
                     _publish_attacker,
+                    record_rotation,
                 )
 
             try:
@@ -626,3 +722,6 @@ async def prober_worker(
         if bus is not None:
             with contextlib.suppress(Exception):
                 await bus.close()
+        if rotation_engine is not None:
+            with contextlib.suppress(Exception):
+                rotation_engine.dispose()

decnet/web/db/models/__init__.py

@@ -45,6 +45,7 @@ from .auth import (
 from .attackers import (
     Attacker,
     AttackerBehavior,
+    AttackerFingerprintState,
     AttackerIdentity,
     AttackersResponse,
     SessionProfile,
@@ -242,6 +243,7 @@ __all__ = [
     # attackers
     "Attacker",
     "AttackerBehavior",
+    "AttackerFingerprintState",
     "AttackerIdentity",
     "AttackerIntel",
     "AttackersResponse",

decnet/web/db/models/attackers.py

@@ -93,11 +93,48 @@ class Attacker(SQLModel, table=True):
     # private/loopback addresses never resolve.  256 chars matches
     # RFC 1035 max hostname length.
     ptr_record: Optional[str] = Field(default=None, max_length=256)
+    # Substrate-rotation telemetry, maintained by
+    # ``decnet.correlation.fingerprint_rotation.record_fingerprint`` whenever
+    # the prober observes a new hash for an (attacker, port, probe_type)
+    # triple it has seen before.  Lets the dashboard render "rotated 3×
+    # last 24h" without joining to AttackerFingerprintState.
+    rotation_count: int = Field(default=0)
+    last_rotation_at: Optional[datetime] = Field(default=None, index=True)
     updated_at: datetime = Field(
         default_factory=lambda: datetime.now(timezone.utc), index=True
     )
 
 
+class AttackerFingerprintState(SQLModel, table=True):
+    """Per-(attacker, port, probe_type) latest-hash row.
+
+    Sole purpose: give the prober memory across runs so it can detect when
+    an attacker's HASSH/JARM/TCP fingerprint flips for the same port — i.e.
+    they rotated their VPS, rebuilt their SSH server, swapped their TLS
+    cert.  Diff detection lives in
+    ``decnet.correlation.fingerprint_rotation``; the prober calls into
+    that library inline at each emit site and this table is the only
+    persistence it needs.
+
+    Bounded by ``attackers × probe families × ports`` — small in practice;
+    a busy fleet sees O(thousands) of rows, not O(millions).
+    """
+    __tablename__ = "attacker_fingerprint_state"
+    uuid: str = Field(primary_key=True)
+    attacker_uuid: str = Field(foreign_key="attackers.uuid", index=True)
+    port: int
+    probe_type: str = Field(max_length=16)  # "jarm" | "hassh" | "tcpfp"
+    last_hash: str = Field(max_length=128)
+    last_seen: datetime = Field(index=True)
+    rotation_count: int = Field(default=0)
+    __table_args__ = (
+        UniqueConstraint(
+            "attacker_uuid", "port", "probe_type",
+            name="uq_attacker_fingerprint_state_natural",
+        ),
+    )
+
+
 class AttackerIdentity(SQLModel, table=True):
     """
     Resolved actor identity — the dedup'd "same hands" row that one or

development/DEBT.md

@@ -470,22 +470,14 @@ The threat-intel enrichment surface (DEBT-N/A: `feat(intel)` series) keys every
 
 **Status:** Open. No operational impact today (single-IP attackers are the dominant case), but worth closing before the federation layer lands so the wire-format and API both speak in identity terms, not IP terms.
 
-### DEBT-032 — Prober can't detect fingerprint rotation without mutation
+### ~~DEBT-032 — Attacker fingerprint rotation detection~~ ✅ RESOLVED
-**Files:** `decnet/prober/worker.py` (~lines 235, 286, 334, 392), `decnet/web/db/models.py` (new `decky_service_fingerprints` table).
+**Files:** `decnet/correlation/fingerprint_rotation.py` (new), `decnet/prober/worker.py`, `decnet/web/db/models/attackers.py`, `decnet/bus/topics.py`.
 
-Substrate identity is `(service_name, implementation_fingerprint)`, not service name alone. A base-image rebuild that rotates OpenSSH 8.4 → 9.2 — or any recompose that changes JARM / HASSH / TCP fingerprint without changing the service list — is a substrate transition from the attacker's recon POV, and today the correlation graph sees none of it.
+Resolved 2026-05-03. **Reframed during planning:** the original entry described this as a per-decky substrate-integrity problem, but the prober probes *attackers*, not deckies. The actual gap was attacker substrate tracking — same attacker IP rotating their VPS, rebuilding their SSH server, swapping their TLS cert — invisible at correlator-time because nothing diffed consecutive hashes for the same `(attacker_ip, port, probe_type)` triple.
 
-The prober already computes JARM (`worker.py:286`), HASSH (`worker.py:334`), and TCP fingerprint (`worker.py:392`), and emits each as RFC 5424 syslog + optional bus publish. What's missing is **per-(decky, service, probe_type) persistence** to diff against: the current dedup set `probed: dict[IP → {probe_type → set(ports)}]` (`worker.py:235`) is in-memory and scoped to one run, so any restart loses history and any same-IP probe on a changed substrate can't be detected as a change.
+Implemented as a small library (`decnet.correlation.fingerprint_rotation.record_fingerprint`) called inline from the prober at each of the three emit sites (JARM / HASSH / TCPFP). No new worker daemon; the prober is still the only producer, just teaches it to derive a second event on hash flip. New `AttackerFingerprintState` table holds per-`(attacker_uuid, port, probe_type)` last-hash state. New bus topic `attacker.fingerprint_rotated` carries `{attacker_uuid, attacker_ip, port, probe_type, old_hash, new_hash, rotation_count, ts}`. `Attacker.rotation_count` and `Attacker.last_rotation_at` are stamped on every diff so the dashboard can render rotation telemetry without joining. Library is fully sync + unit-tested with injected publish_fn / syslog_fn callbacks.
 
-**Design:**
+Out of scope (deferred): dashboard surfacing of `rotation_count`; attribution clustering across attackers (same JARM seen from different IPs); backfill from existing event store.
-1. New SQLModel table `decky_service_fingerprints` keyed by `(decky_name, service, probe_type)` with `last_hash, last_seen_at, sample_count`. One upsert per probe; bounded by fleet × probe families.
-2. Prober reads `last_hash` before emitting; on diff, emits a new `substrate_fingerprint_changed` event (RFC 5424 syslog + `decky.{id}.fingerprint` bus topic) with `{decky, service, probe_type, old_hash, new_hash}`. On match, upsert the timestamp and skip the event.
-3. Correlator consumes the new event kind into a parallel per-decky index (mirroring the mutation index landed in this session) and interleaves `🔍 decky-03 hassh drift` markers in `AttackerTraversal.fingerprints_during`.
-4. Divergence detector: compare `substrate_state(t)` fold (mutations) vs `observed_identity(t)` fold (fingerprints) per decky. A fingerprint change without a preceding mutation ⇒ `substrate_divergence` finding — container drift, compromised base image, rootkit banner rewrite, or prober lag. Falls out of the data model for free once both streams exist.
-
-**Prerequisite satisfied:** mutation event stream + correlator mutation-kind parser landed alongside this DEBT entry (commits `f875350`, `fa0cdb3`, `bf5ed7a`, `d4d8a2a` on `dev`). The fingerprint stream plugs into the same substrate: same RFC 5424 emission pattern, sibling per-decky engine index, same timeline interleaving.
-
-**Status:** Open — deferred to its own commit sequence. The dedup state in `worker.py:235` is the only thing standing between "JARM hash computed" and "substrate rotation detected."
 
 ---
 
@@ -713,7 +705,7 @@ user who needs it.
 | DEBT-029 | 🟡 Medium | Architecture / Bus | ✅ resolved |
 | DEBT-030 | 🟡 Medium | Web / Live mutations | ✅ resolved (Phase A) |
 | ~~DEBT-031~~ | ✅ | Workers / Bus integration | resolved |
-| DEBT-032 | 🟡 Medium | Correlation / Prober | open |
+| ~~DEBT-032~~ | ✅ | Correlation / Prober | resolved 2026-05-03 |
 | DEBT-033 | 🟡 Medium | Storage / Session recording | open |
 | ~~DEBT-035~~ | ✅ | Artifacts / Filesystem perms | resolved 2026-05-02 |
 | DEBT-036 | 🟡 Medium | Correlation / Keystroke dynamics | open |
@@ -731,5 +723,5 @@ user who needs it.
 | DEBT-048 | 🟡 Medium | TTP / Intel provider mapping review (recurring) | open / recurring |
 | DEBT-049 | 🟡 Medium | TTP / Sigma adapter (post-v1) | open |
 
-**Remaining open:** DEBT-011 (Alembic), DEBT-027 (Dynamic bait store), DEBT-028 (deploy endpoint tests), DEBT-032 (fingerprint rotation detection), DEBT-033 (transcript shard rotation), DEBT-036 (session-profile ingester), DEBT-037 (webhook delivery hardening), DEBT-038 (SSH PAM cred-capture limitations — document-only), DEBT-042 (orchestrator failure-count window), DEBT-043 (frontend test framework), DEBT-045 (EmailLifter heavyweight — partial paid; carved-out follow-ups remain), DEBT-046 (mal-hash feed), DEBT-048 (TTP intel provider mapping review — recurring quarterly), DEBT-049 (TTP Sigma adapter — post-v1).
+**Remaining open:** DEBT-011 (Alembic), DEBT-027 (Dynamic bait store), DEBT-028 (deploy endpoint tests), DEBT-033 (transcript shard rotation), DEBT-036 (session-profile ingester), DEBT-037 (webhook delivery hardening), DEBT-038 (SSH PAM cred-capture limitations — document-only), DEBT-042 (orchestrator failure-count window), DEBT-043 (frontend test framework), DEBT-045 (EmailLifter heavyweight — partial paid; carved-out follow-ups remain), DEBT-046 (mal-hash feed), DEBT-048 (TTP intel provider mapping review — recurring quarterly), DEBT-049 (TTP Sigma adapter — post-v1).
 **Estimated remaining effort:** ~21 hours plus the new EmailLifter / TTP follow-ups. DEBT-030 Phase B (optimistic staged-buffer editor) is a follow-up, not debt.

tests/correlation/test_fingerprint_rotation.py

@@ -0,0 +1,236 @@
+"""Unit tests for ``decnet.correlation.fingerprint_rotation``.
+
+Pure library: in-memory SQLite + sync Session + collected callback
+calls.  No prober, no bus, no async.  Each test seeds an Attacker row,
+calls ``record_fingerprint``, asserts on the returned outcome + the
+side-effects (state row, Attacker stamp, callback invocations).
+"""
+from __future__ import annotations
+
+from datetime import datetime, timedelta, timezone
+
+import pytest
+from sqlalchemy.engine import Engine
+from sqlmodel import Session, SQLModel, create_engine, select
+
+from decnet.correlation.fingerprint_rotation import (
+    record_fingerprint,
+    RotationOutcome,
+)
+from decnet.web.db.models import (
+    Attacker,
+    AttackerFingerprintState,
+)
+
+
+@pytest.fixture
+def engine() -> Engine:
+    eng = create_engine("sqlite://", connect_args={"check_same_thread": False})
+    SQLModel.metadata.create_all(eng)
+    return eng
+
+
+@pytest.fixture
+def now() -> datetime:
+    return datetime(2026, 5, 3, 12, 0, 0, tzinfo=timezone.utc)
+
+
+def _seed_attacker(session: Session, ip: str = "1.2.3.4") -> Attacker:
+    a = Attacker(
+        uuid="attacker-uuid-1",
+        ip=ip,
+        first_seen=datetime.now(timezone.utc),
+        last_seen=datetime.now(timezone.utc),
+    )
+    session.add(a)
+    session.commit()
+    session.refresh(a)
+    return a
+
+
+class _Recorder:
+    """Capture (event_type, payload) tuples from publish_fn / syslog_fn."""
+    def __init__(self) -> None:
+        self.calls: list[tuple[str, dict]] = []
+
+    def __call__(self, event_type: str, payload: dict) -> None:
+        self.calls.append((event_type, payload))
+
+
+def test_no_attacker_row_returns_noop(engine, now):
+    publish, syslog = _Recorder(), _Recorder()
+    with Session(engine) as session:
+        outcome = record_fingerprint(
+            session,
+            attacker_ip="9.9.9.9",
+            port=22,
+            probe_type="hassh",
+            new_hash="abc",
+            ts=now,
+            publish_fn=publish,
+            syslog_fn=syslog,
+        )
+    assert outcome.kind == "no_attacker_row"
+    assert publish.calls == []
+    assert syslog.calls == []
+    with Session(engine) as session:
+        rows = session.exec(select(AttackerFingerprintState)).all()
+    assert rows == []
+
+
+def test_first_sighting_creates_state_row_no_event(engine, now):
+    publish, syslog = _Recorder(), _Recorder()
+    with Session(engine) as session:
+        _seed_attacker(session)
+        outcome = record_fingerprint(
+            session,
+            attacker_ip="1.2.3.4",
+            port=22,
+            probe_type="hassh",
+            new_hash="hash-1",
+            ts=now,
+            publish_fn=publish,
+            syslog_fn=syslog,
+        )
+    assert outcome.kind == "first_sighting"
+    assert outcome.old_hash is None
+    assert outcome.new_hash == "hash-1"
+    assert outcome.rotation_count == 0
+    assert publish.calls == []
+    assert syslog.calls == []
+    with Session(engine) as session:
+        rows = session.exec(select(AttackerFingerprintState)).all()
+        assert len(rows) == 1
+        assert rows[0].last_hash == "hash-1"
+        assert rows[0].rotation_count == 0
+        a = session.exec(select(Attacker)).one()
+        assert a.rotation_count == 0
+        assert a.last_rotation_at is None
+
+
+def test_unchanged_hash_bumps_last_seen_no_event(engine, now):
+    publish, syslog = _Recorder(), _Recorder()
+    later = now + timedelta(minutes=10)
+    with Session(engine) as session:
+        _seed_attacker(session)
+        record_fingerprint(
+            session,
+            attacker_ip="1.2.3.4", port=22, probe_type="hassh",
+            new_hash="hash-1", ts=now,
+        )
+        outcome = record_fingerprint(
+            session,
+            attacker_ip="1.2.3.4", port=22, probe_type="hassh",
+            new_hash="hash-1", ts=later,
+            publish_fn=publish, syslog_fn=syslog,
+        )
+    assert outcome.kind == "unchanged"
+    assert publish.calls == []
+    assert syslog.calls == []
+    with Session(engine) as session:
+        row = session.exec(select(AttackerFingerprintState)).one()
+        # SQLite strips tzinfo on round-trip; compare naive values.
+        assert row.last_seen.replace(tzinfo=timezone.utc) == later
+        assert row.rotation_count == 0
+
+
+def test_rotated_emits_event_and_stamps_attacker(engine, now):
+    publish, syslog = _Recorder(), _Recorder()
+    later = now + timedelta(hours=1)
+    with Session(engine) as session:
+        _seed_attacker(session)
+        record_fingerprint(
+            session,
+            attacker_ip="1.2.3.4", port=22, probe_type="hassh",
+            new_hash="hash-1", ts=now,
+        )
+        outcome = record_fingerprint(
+            session,
+            attacker_ip="1.2.3.4", port=22, probe_type="hassh",
+            new_hash="hash-2", ts=later,
+            publish_fn=publish, syslog_fn=syslog,
+        )
+
+    assert outcome.kind == "rotated"
+    assert outcome.old_hash == "hash-1"
+    assert outcome.new_hash == "hash-2"
+    assert outcome.rotation_count == 1
+
+    assert len(publish.calls) == 1
+    assert len(syslog.calls) == 1
+    event_type, payload = publish.calls[0]
+    assert event_type == "attacker.fingerprint_rotated"
+    assert payload["attacker_uuid"] == "attacker-uuid-1"
+    assert payload["attacker_ip"] == "1.2.3.4"
+    assert payload["port"] == 22
+    assert payload["probe_type"] == "hassh"
+    assert payload["old_hash"] == "hash-1"
+    assert payload["new_hash"] == "hash-2"
+    assert payload["rotation_count"] == 1
+    assert payload["ts"] == later.isoformat()
+
+    with Session(engine) as session:
+        a = session.exec(select(Attacker)).one()
+        assert a.rotation_count == 1
+        assert a.last_rotation_at is not None
+        assert a.last_rotation_at.replace(tzinfo=timezone.utc) == later
+        row = session.exec(select(AttackerFingerprintState)).one()
+        assert row.last_hash == "hash-2"
+        assert row.rotation_count == 1
+
+
+def test_three_probe_types_independent(engine, now):
+    with Session(engine) as session:
+        _seed_attacker(session)
+        for ptype in ("jarm", "hassh", "tcpfp"):
+            record_fingerprint(
+                session,
+                attacker_ip="1.2.3.4", port=22, probe_type=ptype,
+                new_hash=f"{ptype}-1", ts=now,
+            )
+    with Session(engine) as session:
+        rows = session.exec(select(AttackerFingerprintState)).all()
+    assert {r.probe_type for r in rows} == {"jarm", "hassh", "tcpfp"}
+    assert {r.last_hash for r in rows} == {"jarm-1", "hassh-1", "tcpfp-1"}
+
+
+def test_two_ports_same_probe_type_independent(engine, now):
+    with Session(engine) as session:
+        _seed_attacker(session)
+        for port in (22, 2222):
+            record_fingerprint(
+                session,
+                attacker_ip="1.2.3.4", port=port, probe_type="hassh",
+                new_hash=f"hash-{port}", ts=now,
+            )
+    with Session(engine) as session:
+        rows = session.exec(select(AttackerFingerprintState)).all()
+    assert {r.port for r in rows} == {22, 2222}
+
+
+def test_multiple_rotations_increment_counter(engine, now):
+    publish = _Recorder()
+    with Session(engine) as session:
+        _seed_attacker(session)
+        record_fingerprint(
+            session,
+            attacker_ip="1.2.3.4", port=22, probe_type="hassh",
+            new_hash="h1", ts=now, publish_fn=publish,
+        )
+        record_fingerprint(
+            session,
+            attacker_ip="1.2.3.4", port=22, probe_type="hassh",
+            new_hash="h2", ts=now + timedelta(minutes=5), publish_fn=publish,
+        )
+        record_fingerprint(
+            session,
+            attacker_ip="1.2.3.4", port=22, probe_type="hassh",
+            new_hash="h3", ts=now + timedelta(minutes=10), publish_fn=publish,
+        )
+    assert len(publish.calls) == 2  # first call was first_sighting (no event)
+    with Session(engine) as session:
+        a = session.exec(select(Attacker)).one()
+        assert a.rotation_count == 2
+        row = session.exec(select(AttackerFingerprintState)).one()
+        assert row.rotation_count == 2
+        assert row.last_hash == "h3"

tests/prober/test_prober_rotation.py

@@ -0,0 +1,142 @@
+"""Integration test: prober phase functions invoke the rotation recorder.
+
+The prober worker constructs the recorder closure at startup; here we
+verify that ``_probe_cycle`` threads a recorder through to JARM / HASSH
+/ TCPFP phases and that the recorder gets the (ip, port, probe_type,
+hash) tuple it expects.  The library itself is unit-tested separately.
+"""
+from __future__ import annotations
+
+from pathlib import Path
+from unittest.mock import MagicMock, patch
+
+from decnet.prober.worker import _probe_cycle
+
+
+@patch("decnet.prober.worker.fetch_leaf_cert", return_value=None)
+@patch("decnet.prober.worker.tcp_fingerprint", return_value=None)
+@patch("decnet.prober.worker.hassh_server", return_value=None)
+@patch("decnet.prober.worker.jarm_hash")
+def test_jarm_phase_calls_recorder(
+    mock_jarm: MagicMock,
+    _mock_hassh: MagicMock,
+    _mock_tcpfp: MagicMock,
+    _mock_cert: MagicMock,
+    tmp_path: Path,
+):
+    mock_jarm.return_value = "c0c" * 10 + "a" * 32
+    log_path = tmp_path / "decnet.log"
+    json_path = tmp_path / "decnet.json"
+    rec_calls: list[tuple] = []
+    recorder = lambda ip, port, ptype, h: rec_calls.append((ip, port, ptype, h))  # noqa: E731
+
+    _probe_cycle(
+        {"10.0.0.5"}, {},
+        [443], [], [],
+        log_path, json_path,
+        timeout=1.0,
+        publish_fn=None,
+        record_rotation=recorder,
+    )
+
+    assert rec_calls == [("10.0.0.5", 443, "jarm", "c0c" * 10 + "a" * 32)]
+
+
+@patch("decnet.prober.worker.fetch_leaf_cert", return_value=None)
+@patch("decnet.prober.worker.tcp_fingerprint", return_value=None)
+@patch("decnet.prober.worker.hassh_server")
+@patch("decnet.prober.worker.jarm_hash", return_value="")
+def test_hassh_phase_calls_recorder(
+    _mock_jarm: MagicMock,
+    mock_hassh: MagicMock,
+    _mock_tcpfp: MagicMock,
+    _mock_cert: MagicMock,
+    tmp_path: Path,
+):
+    mock_hassh.return_value = {
+        "hassh_server": "deadbeef",
+        "banner": "SSH-2.0-OpenSSH_9.2",
+        "kex_algorithms": "x",
+        "encryption_s2c": "x",
+        "mac_s2c": "x",
+        "compression_s2c": "x",
+    }
+    log_path = tmp_path / "decnet.log"
+    json_path = tmp_path / "decnet.json"
+    rec_calls: list[tuple] = []
+    recorder = lambda ip, port, ptype, h: rec_calls.append((ip, port, ptype, h))  # noqa: E731
+
+    _probe_cycle(
+        {"10.0.0.5"}, {},
+        [], [22], [],
+        log_path, json_path,
+        timeout=1.0,
+        publish_fn=None,
+        record_rotation=recorder,
+    )
+
+    assert rec_calls == [("10.0.0.5", 22, "hassh", "deadbeef")]
+
+
+@patch("decnet.prober.worker.fetch_leaf_cert", return_value=None)
+@patch("decnet.prober.worker.tcp_fingerprint")
+@patch("decnet.prober.worker.hassh_server", return_value=None)
+@patch("decnet.prober.worker.jarm_hash", return_value="")
+def test_tcpfp_phase_calls_recorder(
+    _mock_jarm, _mock_hassh, mock_tcpfp, _mock_cert, tmp_path: Path,
+):
+    mock_tcpfp.return_value = {
+        "tcpfp_hash": "tcpfp-hash-1",
+        "tcpfp_raw": "raw",
+        "ttl": 64,
+        "window_size": 65535,
+        "df_bit": True,
+        "mss": 1460,
+        "window_scale": 7,
+        "sack_ok": True,
+        "timestamp": True,
+        "options_order": "MSS,SACK,TS,NOP,WS",
+        "tos": 0,
+        "dscp": 0,
+        "ecn": 0,
+        "server_isn": 0,
+    }
+    log_path = tmp_path / "decnet.log"
+    json_path = tmp_path / "decnet.json"
+    rec_calls: list[tuple] = []
+    recorder = lambda ip, port, ptype, h: rec_calls.append((ip, port, ptype, h))  # noqa: E731
+
+    _probe_cycle(
+        {"10.0.0.5"}, {},
+        [], [], [22],
+        log_path, json_path,
+        timeout=1.0,
+        publish_fn=None,
+        record_rotation=recorder,
+    )
+
+    assert rec_calls == [("10.0.0.5", 22, "tcpfp", "tcpfp-hash-1")]
+
+
+@patch("decnet.prober.worker.fetch_leaf_cert", return_value=None)
+@patch("decnet.prober.worker.tcp_fingerprint", return_value=None)
+@patch("decnet.prober.worker.hassh_server", return_value=None)
+@patch("decnet.prober.worker.jarm_hash")
+def test_recorder_optional_no_crash_when_none(
+    mock_jarm: MagicMock,
+    _mock_hassh: MagicMock,
+    _mock_tcpfp: MagicMock,
+    _mock_cert: MagicMock,
+    tmp_path: Path,
+):
+    """record_rotation=None must keep the prober's pre-DEBT-032 behavior."""
+    mock_jarm.return_value = "c0c" * 10 + "a" * 32
+    _probe_cycle(
+        {"10.0.0.5"}, {},
+        [443], [], [],
+        tmp_path / "decnet.log", tmp_path / "decnet.json",
+        timeout=1.0,
+        publish_fn=None,
+        record_rotation=None,
+    )
+    # No error, probe completes.