diff --git a/arborist/cli.py b/arborist/cli.py
index 82ae826..fef6a78 100644
--- a/arborist/cli.py
+++ b/arborist/cli.py
@@ -2721,6 +2721,116 @@ def _cmd_snapshot_diff(args: argparse.Namespace) -> int:
     return 0
 
 
+def _cmd_memory_snapshot(args: argparse.Namespace) -> int:
+    """Build a memory snapshot from current store state and persist it."""
+    from arborist.memory import snapshot, store_snapshot
+
+    conn = connect(args.db)
+    try:
+        with transaction(conn):
+            ms = snapshot(conn)
+            root = store_snapshot(conn, ms)
+    finally:
+        conn.close()
+    print(json.dumps({"memory_root": root}, indent=2, ensure_ascii=False))
+    return 0
+
+
+def _cmd_memory_show(args: argparse.Namespace) -> int:
+    """Print a memory record by root, or the latest live one."""
+    from arborist.memory import branches_for, latest, load
+
+    conn = connect(args.db)
+    try:
+        if args.root:
+            row = load(conn, args.root)
+        else:
+            row = latest(conn)
+        if row is None:
+            print(json.dumps({"error": "no memory snapshot found"}, indent=2))
+            return 1
+        body = row["branch_summaries_blob"]
+        if isinstance(body, (bytes, bytearray)):
+            body = body.decode("utf-8", errors="replace")
+        out = {
+            "memory_root": row["memory_root"],
+            "state": row["state"],
+            "schema_version": row["schema_version"],
+            "parent_memory_root": row["parent_memory_root"],
+            "audit_events_high_water": row["audit_events_high_water"],
+            "audit_event_hash": row["audit_event_hash"],
+            "created_at": row["created_at"],
+            "falsified_at": row["falsified_at"],
+            "falsified_reason": row["falsified_reason"],
+            "body": body,
+            "branches": branches_for(conn, row["memory_root"]),
+        }
+    finally:
+        conn.close()
+    print(json.dumps(out, indent=2, ensure_ascii=False, default=str))
+    return 0
+
+
+def _cmd_memory_branches(args: argparse.Namespace) -> int:
+    """List branch summaries attached to a memory_root."""
+    from arborist.memory import branches_for, latest
+
+    conn = connect(args.db)
+    try:
+        if args.root:
+            root = args.root
+        else:
+            row = latest(conn)
+            if row is None:
+                print(json.dumps([], indent=2))
+                return 0
+            root = row["memory_root"]
+        out = branches_for(conn, root)
+    finally:
+        conn.close()
+
+    # Decode summary_blob to text for human inspection.
+    rendered = []
+    for b in out:
+        rec = dict(b)
+        if isinstance(rec["summary_blob"], (bytes, bytearray)):
+            rec["summary_blob"] = rec["summary_blob"].decode(
+                "utf-8", errors="replace"
+            )
+        rendered.append(rec)
+    print(json.dumps(rendered, indent=2, ensure_ascii=False, default=str))
+    return 0
+
+
+def _cmd_memory_falsify(args: argparse.Namespace) -> int:
+    """Mark a memory_root falsified."""
+    from arborist.memory import falsify
+
+    conn = connect(args.db)
+    try:
+        with transaction(conn):
+            event_hash = falsify(
+                conn,
+                args.root,
+                reason=args.reason,
+                triggering_branch_id=args.branch_id,
+            )
+    finally:
+        conn.close()
+    print(
+        json.dumps(
+            {
+                "memory_root": args.root,
+                "audit_event_hash": event_hash or None,
+                "noop": event_hash == "",
+            },
+            indent=2,
+            ensure_ascii=False,
+        )
+    )
+    return 0
+
+
 def _cmd_capital_summary(args: argparse.Namespace) -> int:
     """Aggregate capital_ledger totals; per-form sums + row count."""
     from arborist.capital import summary as capital_summary
@@ -4181,6 +4291,58 @@ def build_parser() -> argparse.ArgumentParser:
     snap_diff.add_argument("snapshot_root", help="hex snapshot_root to diff against current")
     snap_diff.set_defaults(func=_cmd_snapshot_diff)
 
+    # ----- memory subcommands (ticket #000017) --------------------------------
+    memory_cmd = sub.add_parser(
+        "memory",
+        help="lifelong-learning audit summary (ticket #000017)",
+    )
+    memory_sub = memory_cmd.add_subparsers(
+        dest="memory_op", required=True
+    )
+
+    mem_snap = memory_sub.add_parser(
+        "snapshot",
+        help="build a memory snapshot from current store state",
+    )
+    mem_snap.set_defaults(func=_cmd_memory_snapshot)
+
+    mem_show = memory_sub.add_parser(
+        "show",
+        help="print a memory record by root, or the latest live one",
+    )
+    mem_show.add_argument(
+        "--root",
+        default=None,
+        help="hex memory_root (default: latest live)",
+    )
+    mem_show.set_defaults(func=_cmd_memory_show)
+
+    mem_branches = memory_sub.add_parser(
+        "branches",
+        help="list branch summaries attached to a memory_root",
+    )
+    mem_branches.add_argument(
+        "--root",
+        default=None,
+        help="hex memory_root (default: latest live)",
+    )
+    mem_branches.set_defaults(func=_cmd_memory_branches)
+
+    mem_fals = memory_sub.add_parser(
+        "falsify", help="mark a memory_root falsified"
+    )
+    mem_fals.add_argument("root", help="hex memory_root to falsify")
+    mem_fals.add_argument(
+        "--reason", required=True, help="why this memory is falsified"
+    )
+    mem_fals.add_argument(
+        "--branch-id",
+        dest="branch_id",
+        default=None,
+        help="optional triggering branch_id",
+    )
+    mem_fals.set_defaults(func=_cmd_memory_falsify)
+
     # ----- capital subcommands (ticket #000020) -------------------------------
     capital_cmd = sub.add_parser(
         "capital",
diff --git a/arborist/memory/__init__.py b/arborist/memory/__init__.py
new file mode 100644
index 0000000..9cf3e27
--- /dev/null
+++ b/arborist/memory/__init__.py
@@ -0,0 +1,58 @@
+"""Memory-root: lifelong-learning audit summary (ticket #000017).
+
+Distinct from per-cache_key providence answers and per-event audit
+chain — ``memory_root`` is a periodic, deterministic projection over
+``audit_events`` that summarizes recurring failure motifs, accepted
+corrections, and other cross-query state.
+
+Hierarchical layout (per ticket #000017 §2.1):
+
+- One ``memory_records`` row per snapshot, with ``memory_root``
+  derived from the canonical body bytes.
+- Multiple ``memory_branch_summaries`` rows per snapshot, one per
+  named branch (e.g., ``failure-motif:title-mismatch``,
+  ``failure-motif:warrant-missing``).
+
+Each branch's ``summary_blob`` is a deterministic projection of a
+slice of ``audit_events``; the projection rule is committed by
+canonical-JSON-hashing it as part of the branch summary's preimage.
+
+Public surface:
+
+- :func:`snapshot` — build a memory_root + branch summaries from
+  current store state.
+- :func:`store_snapshot` — persist snapshot + emit
+  ``memory_snapshot_landed`` audit event.
+- :func:`falsify` / :func:`mark_stale` — state transitions.
+- :func:`load` / :func:`latest` / :func:`branches_for` — read APIs.
+"""
+
+from __future__ import annotations
+
+from arborist.memory.canonical import (
+    SCHEMA_VERSION,
+    BranchSummary,
+    MemorySnapshot,
+    branch_digest,
+    canonical_branches_blob,
+    memory_root,
+)
+from arborist.memory.falsify import falsify, mark_stale
+from arborist.memory.snapshot import snapshot
+from arborist.memory.store import branches_for, latest, load, store_snapshot
+
+__all__ = [
+    "SCHEMA_VERSION",
+    "BranchSummary",
+    "MemorySnapshot",
+    "branch_digest",
+    "canonical_branches_blob",
+    "memory_root",
+    "snapshot",
+    "store_snapshot",
+    "falsify",
+    "mark_stale",
+    "load",
+    "latest",
+    "branches_for",
+]
diff --git a/arborist/memory/canonical.py b/arborist/memory/canonical.py
new file mode 100644
index 0000000..c2cd79d
--- /dev/null
+++ b/arborist/memory/canonical.py
@@ -0,0 +1,102 @@
+"""Canonical encoding for memory snapshots and branch summaries.
+
+Determinism rules (per ticket #000017):
+
+- Branch IDs are stable strings (``failure-motif:title-mismatch``,
+  ``correction:operator-applied``). Adding a branch type is a new
+  ``schema_version`` (``memory-v1`` → ``memory-v2``).
+- ``branch_digest`` over the (branch_id, summary_blob, count) triple
+  pins each branch independently — re-running the projection on
+  the same audit slice produces the same digest.
+- ``memory_root`` is SHA-256 over the canonical-JSON of:
+  ``{schema_version, parent_memory_root, audit_events_high_water,
+  branch_digests}`` where ``branch_digests`` is a sorted list of
+  ``{"branch_id": ..., "digest": ..., "count": ...}`` triples.
+"""
+
+from __future__ import annotations
+
+import hashlib
+import json
+from dataclasses import dataclass, field
+from typing import Optional
+
+
+SCHEMA_VERSION = "memory-v1"
+
+
+@dataclass(frozen=True)
+class BranchSummary:
+    """One branch of a memory snapshot.
+
+    ``summary_blob`` is the deterministic projection output for this
+    branch — its content is opaque to ``canonical.py`` but must be
+    bytes-stable for the same audit slice.
+    """
+
+    branch_id: str
+    summary_blob: bytes
+    count: int
+
+    def canonical(self) -> dict:
+        return {
+            "branch_id": self.branch_id,
+            "digest": branch_digest(self),
+            "count": int(self.count),
+        }
+
+
+def branch_digest(summary: BranchSummary) -> str:
+    """SHA-256 over (branch_id, summary_blob bytes, count)."""
+    h = hashlib.sha256()
+    h.update(summary.branch_id.encode("utf-8", errors="surrogatepass"))
+    h.update(b"\x00")
+    h.update(summary.summary_blob)
+    h.update(b"\x00")
+    h.update(str(int(summary.count)).encode("ascii"))
+    return h.hexdigest()
+
+
+@dataclass(frozen=True)
+class MemorySnapshot:
+    """Memory snapshot record body (pre-persistence).
+
+    ``audit_events_high_water`` is the ``event_hash`` of the most
+    recent audit event included in the projection — this lets a
+    later snapshot resume from where this one stopped without
+    re-summarizing the whole chain.
+    """
+
+    schema_version: str
+    parent_memory_root: Optional[str]
+    audit_events_high_water: str
+    branches: tuple[BranchSummary, ...] = field(default_factory=tuple)
+
+    def canonical(self) -> dict:
+        # branches are sorted by branch_id so insertion order doesn't
+        # affect the memory_root.
+        sorted_branches = sorted(self.branches, key=lambda b: b.branch_id)
+        return {
+            "schema_version": self.schema_version,
+            "parent_memory_root": self.parent_memory_root,
+            "audit_events_high_water": self.audit_events_high_water,
+            "branches": [b.canonical() for b in sorted_branches],
+        }
+
+
+def canonical_branches_blob(snapshot: MemorySnapshot) -> str:
+    return json.dumps(
+        snapshot.canonical(),
+        sort_keys=True,
+        separators=(",", ":"),
+        ensure_ascii=False,
+    )
+
+
+def memory_root(snapshot: MemorySnapshot) -> str:
+    """SHA-256 over the canonical body bytes."""
+    return hashlib.sha256(
+        canonical_branches_blob(snapshot).encode(
+            "utf-8", errors="surrogatepass"
+        )
+    ).hexdigest()
diff --git a/arborist/memory/falsify.py b/arborist/memory/falsify.py
new file mode 100644
index 0000000..0bcd112
--- /dev/null
+++ b/arborist/memory/falsify.py
@@ -0,0 +1,93 @@
+"""Mark a memory snapshot falsified or stale (ticket #000017 §2.3).
+
+Falsification cascade scope (ticket §2.3 option B): falsifying a
+memory snapshot does NOT auto-rerun upstream-citing records. Operator
+can trigger cascade re-evaluation explicitly via a separate command
+(future ticket).
+"""
+
+from __future__ import annotations
+
+import sqlite3
+import time
+from typing import Optional
+
+from arborist.store import append_audit
+
+
+def falsify(
+    conn: sqlite3.Connection,
+    memory_root: str,
+    *,
+    reason: str,
+    triggering_branch_id: Optional[str] = None,
+    ts: Optional[int] = None,
+) -> str:
+    """Flip memory_root state to ``falsified``; return audit event_hash.
+
+    Idempotent on terminal state.
+    """
+    row = conn.execute(
+        "SELECT state FROM memory_records WHERE memory_root = ?",
+        (memory_root,),
+    ).fetchone()
+    if row is None:
+        raise KeyError(f"memory_root not found: {memory_root}")
+    if row["state"] == "falsified":
+        return ""
+
+    if ts is None:
+        ts = int(time.time())
+
+    event_hash = append_audit(
+        conn,
+        event_type="memory_falsified",
+        subject_root=memory_root,
+        body={
+            "memory_root": memory_root,
+            "reason": reason,
+            "triggering_branch_id": triggering_branch_id,
+        },
+        ts=ts,
+    )
+    conn.execute(
+        "UPDATE memory_records "
+        "SET state = 'falsified', falsified_at = ?, falsified_reason = ? "
+        "WHERE memory_root = ?",
+        (ts, reason, memory_root),
+    )
+    return event_hash
+
+
+def mark_stale(
+    conn: sqlite3.Connection,
+    memory_root: str,
+    *,
+    reason: str,
+    ts: Optional[int] = None,
+) -> str:
+    """Flip memory_root state to ``stale``; return audit event_hash."""
+    row = conn.execute(
+        "SELECT state FROM memory_records WHERE memory_root = ?",
+        (memory_root,),
+    ).fetchone()
+    if row is None:
+        raise KeyError(f"memory_root not found: {memory_root}")
+    if row["state"] in ("stale", "falsified"):
+        return ""
+
+    if ts is None:
+        ts = int(time.time())
+
+    event_hash = append_audit(
+        conn,
+        event_type="memory_marked_stale",
+        subject_root=memory_root,
+        body={"memory_root": memory_root, "reason": reason},
+        ts=ts,
+    )
+    conn.execute(
+        "UPDATE memory_records SET state = 'stale' WHERE memory_root = ?",
+        (memory_root,),
+    )
+    return event_hash
diff --git a/arborist/memory/projections.py b/arborist/memory/projections.py
new file mode 100644
index 0000000..9d90ea5
--- /dev/null
+++ b/arborist/memory/projections.py
@@ -0,0 +1,217 @@
+"""Branch projection rules — deterministic summaries over audit_events.
+
+Each projection function takes a SQLite cursor and a high-water mark
+(or ``None`` for "everything") and returns a :class:`BranchSummary`.
+Projections must be:
+
+1. **Deterministic** — same inputs produce byte-identical
+   ``summary_blob``.
+2. **Idempotent** — running twice on the same slice is a no-op.
+3. **Stable across schema-compatible inserts** — adding a new
+   ``providence_cache`` row that doesn't carry a violation must not
+   shift existing motif counts.
+
+Projection rule version is committed at the snapshot level via
+:data:`PROJECTION_VERSION`. Bumping it is a new ``memory-vN`` and
+invalidates prior snapshots' digests (by design — projection rule
+changes are causal).
+"""
+
+from __future__ import annotations
+
+import json
+import sqlite3
+from collections import Counter
+from typing import Optional
+
+from arborist.memory.canonical import BranchSummary
+
+
+PROJECTION_VERSION = "projections-v1"
+
+
+def _violations_text(body: str) -> list[str]:
+    """Extract the flat list of violation tags from a v9.8 audit body.
+
+    Multiple shapes coexist in the wild:
+    - ``providence_write`` events with verifier_method/audit_mode
+    - ``providence_repair`` events with pre/post audit_mode
+    The verifier-violation tags surface in the in-process verdict and
+    are persisted on the providence_cache row, but in the audit body
+    they show up under various keys depending on the run-DAG node.
+    Projection v1 is deliberately conservative: it reads
+    ``violations`` arrays only, falling through to empty otherwise.
+    """
+    try:
+        obj = json.loads(body)
+    except (TypeError, json.JSONDecodeError):
+        return []
+    raw = obj.get("violations")
+    if isinstance(raw, list):
+        return [str(t) for t in raw if isinstance(t, str)]
+    return []
+
+
+def project_failure_motif_violations(
+    conn: sqlite3.Connection,
+    *,
+    high_water: Optional[str] = None,
+) -> tuple[BranchSummary, str]:
+    """Count violation tags found in providence_cache rows.
+
+    Returns ``(BranchSummary, latest_event_hash)``.
+
+    We project over ``providence_cache`` (where verifier-resolved
+    violations are persisted as JSON in the merkle_proof / row) plus
+    the ``audit_events`` table for `providence_write` / `providence_repair`.
+    Projection v1 reads two columns:
+    - ``providence_cache.unverified_quotes`` — non-null indicates
+      partial verification.
+    - ``audit_events.body`` `violations` array on `providence_write`
+      events.
+    """
+    counter: Counter[str] = Counter()
+
+    # Slice over providence_write events past the high-water.
+    if high_water is None:
+        rows = conn.execute(
+            "SELECT body FROM audit_events "
+            "WHERE event_type = 'providence_write' "
+            "ORDER BY seq"
+        ).fetchall()
+    else:
+        cur = conn.execute(
+            "SELECT seq FROM audit_events WHERE event_hash = ?",
+            (high_water,),
+        ).fetchone()
+        if cur is None:
+            rows = conn.execute(
+                "SELECT body FROM audit_events "
+                "WHERE event_type = 'providence_write' "
+                "ORDER BY seq"
+            ).fetchall()
+        else:
+            rows = conn.execute(
+                "SELECT body FROM audit_events "
+                "WHERE event_type = 'providence_write' AND seq > ? "
+                "ORDER BY seq",
+                (cur["seq"],),
+            ).fetchall()
+
+    for row in rows:
+        for tag in _violations_text(row["body"]):
+            counter[tag] += 1
+
+    # Latest event_hash overall (regardless of branch).
+    latest = conn.execute(
+        "SELECT event_hash FROM audit_events ORDER BY seq DESC LIMIT 1"
+    ).fetchone()
+    latest_hash = latest["event_hash"] if latest else "genesis"
+
+    payload = {
+        "projection_version": PROJECTION_VERSION,
+        "tag_counts": {k: counter[k] for k in sorted(counter)},
+    }
+    blob = json.dumps(
+        payload, sort_keys=True, separators=(",", ":"), ensure_ascii=False
+    ).encode("utf-8", errors="surrogatepass")
+
+    return (
+        BranchSummary(
+            branch_id="failure-motif:violations",
+            summary_blob=blob,
+            count=sum(counter.values()),
+        ),
+        latest_hash,
+    )
+
+
+def project_audit_mode_distribution(
+    conn: sqlite3.Connection,
+    *,
+    high_water: Optional[str] = None,
+) -> BranchSummary:
+    """Count audit_mode outcomes (STRICT/HYBRID/UNGROUNDED) on writes.
+
+    Pure read — does not advance high-water; that's the caller's job.
+    """
+    counter: Counter[str] = Counter()
+
+    if high_water is None:
+        rows = conn.execute(
+            "SELECT body FROM audit_events "
+            "WHERE event_type = 'providence_write' "
+            "ORDER BY seq"
+        ).fetchall()
+    else:
+        cur = conn.execute(
+            "SELECT seq FROM audit_events WHERE event_hash = ?",
+            (high_water,),
+        ).fetchone()
+        cutoff = cur["seq"] if cur else -1
+        rows = conn.execute(
+            "SELECT body FROM audit_events "
+            "WHERE event_type = 'providence_write' AND seq > ? "
+            "ORDER BY seq",
+            (cutoff,),
+        ).fetchall()
+
+    for row in rows:
+        try:
+            obj = json.loads(row["body"])
+        except (TypeError, json.JSONDecodeError):
+            continue
+        mode = obj.get("audit_mode")
+        if isinstance(mode, str):
+            counter[mode] += 1
+
+    payload = {
+        "projection_version": PROJECTION_VERSION,
+        "audit_mode_counts": {k: counter[k] for k in sorted(counter)},
+    }
+    blob = json.dumps(
+        payload, sort_keys=True, separators=(",", ":"), ensure_ascii=False
+    ).encode("utf-8", errors="surrogatepass")
+    return BranchSummary(
+        branch_id="audit-mode-distribution",
+        summary_blob=blob,
+        count=sum(counter.values()),
+    )
+
+
+def project_falsification_counts(
+    conn: sqlite3.Connection,
+    *,
+    high_water: Optional[str] = None,
+) -> BranchSummary:
+    """Count falsification states across providence_cache rows.
+
+    Reflects current state, not historical — useful for snapshot-time
+    triage. The high_water arg is accepted but ignored for this branch
+    (state is a current value, not a temporal accumulation).
+    """
+    rows = conn.execute(
+        "SELECT falsification_state, COUNT(*) AS n FROM providence_cache "
+        "GROUP BY falsification_state"
+    ).fetchall()
+    counts = {r["falsification_state"]: int(r["n"]) for r in rows}
+    payload = {
+        "projection_version": PROJECTION_VERSION,
+        "falsification_counts": {k: counts[k] for k in sorted(counts)},
+    }
+    blob = json.dumps(
+        payload, sort_keys=True, separators=(",", ":"), ensure_ascii=False
+    ).encode("utf-8", errors="surrogatepass")
+    return BranchSummary(
+        branch_id="falsification-state",
+        summary_blob=blob,
+        count=sum(counts.values()),
+    )
+
+
+# Default branch set the snapshotter calls.
+DEFAULT_BRANCHES = (
+    project_failure_motif_violations,
+    project_audit_mode_distribution,
+    project_falsification_counts,
+)
diff --git a/arborist/memory/snapshot.py b/arborist/memory/snapshot.py
new file mode 100644
index 0000000..700bbbe
--- /dev/null
+++ b/arborist/memory/snapshot.py
@@ -0,0 +1,81 @@
+"""Build a memory snapshot from current store state.
+
+The snapshotter is side-effect-free: returns a :class:`MemorySnapshot`.
+Persistence is the caller's job (via :func:`arborist.memory.store_snapshot`).
+"""
+
+from __future__ import annotations
+
+import sqlite3
+from typing import Iterable, Optional
+
+from arborist.memory.canonical import (
+    SCHEMA_VERSION,
+    BranchSummary,
+    MemorySnapshot,
+)
+from arborist.memory.projections import (
+    DEFAULT_BRANCHES,
+    project_failure_motif_violations,
+)
+
+
+def _parent_memory_root(conn: sqlite3.Connection) -> Optional[str]:
+    row = conn.execute(
+        "SELECT memory_root FROM memory_records "
+        "WHERE state = 'live' "
+        "ORDER BY created_at DESC LIMIT 1"
+    ).fetchone()
+    if row is None:
+        return None
+    return row["memory_root"]
+
+
+def snapshot(
+    conn: sqlite3.Connection,
+    *,
+    branches: Optional[Iterable] = None,
+) -> MemorySnapshot:
+    """Build a :class:`MemorySnapshot` over current state.
+
+    Parameters
+    ----------
+    conn:
+        Read-write SQLite connection.
+    branches:
+        Iterable of branch projection functions. Defaults to
+        :data:`DEFAULT_BRANCHES`. Each function takes the connection
+        and an optional ``high_water`` kwarg and returns either a
+        :class:`BranchSummary` or a ``(BranchSummary, latest_hash)``
+        tuple.
+    """
+    parent = _parent_memory_root(conn)
+
+    if branches is None:
+        branches = DEFAULT_BRANCHES
+
+    summaries: list[BranchSummary] = []
+    high_water = "genesis"
+    for fn in branches:
+        # Some projections also return the latest event hash they saw.
+        result = fn(conn)
+        if isinstance(result, tuple):
+            summary, latest_hash = result
+            high_water = latest_hash
+        else:
+            summary = result
+        summaries.append(summary)
+
+    # If no branch surfaced a high-water, look one up directly.
+    if high_water == "genesis":
+        latest = conn.execute(
+            "SELECT event_hash FROM audit_events ORDER BY seq DESC LIMIT 1"
+        ).fetchone()
+        high_water = latest["event_hash"] if latest else "genesis"
+
+    return MemorySnapshot(
+        schema_version=SCHEMA_VERSION,
+        parent_memory_root=parent,
+        audit_events_high_water=high_water,
+        branches=tuple(summaries),
+    )
diff --git a/arborist/memory/store.py b/arborist/memory/store.py
new file mode 100644
index 0000000..a3cfb05
--- /dev/null
+++ b/arborist/memory/store.py
@@ -0,0 +1,134 @@
+"""CRUD over ``memory_records`` + ``memory_branch_summaries``.
+
+Persistence emits ``memory_snapshot_landed`` audit event tied to the
+new memory_root. Branch summaries are written one row per branch,
+content-addressed by ``branch_digest``.
+"""
+
+from __future__ import annotations
+
+import sqlite3
+import time
+from typing import Iterable, Optional
+
+from arborist.memory.canonical import (
+    BranchSummary,
+    MemorySnapshot,
+    branch_digest,
+    canonical_branches_blob,
+    memory_root,
+)
+from arborist.store import append_audit
+
+
+def store_snapshot(
+    conn: sqlite3.Connection,
+    snapshot: MemorySnapshot,
+    *,
+    ts: Optional[int] = None,
+) -> str:
+    """Persist a memory snapshot + its branch summaries; return memory_root.
+
+    Idempotent on (memory_root): re-storing the same snapshot is a no-op.
+    """
+    root = memory_root(snapshot)
+    body_blob = canonical_branches_blob(snapshot).encode(
+        "utf-8", errors="surrogatepass"
+    )
+    if ts is None:
+        ts = int(time.time())
+
+    existing = conn.execute(
+        "SELECT 1 FROM memory_records WHERE memory_root = ?", (root,)
+    ).fetchone()
+    if existing is not None:
+        return root
+
+    event_hash = append_audit(
+        conn,
+        event_type="memory_snapshot_landed",
+        subject_root=root,
+        body={
+            "memory_root": root,
+            "schema_version": snapshot.schema_version,
+            "parent_memory_root": snapshot.parent_memory_root,
+            "branch_count": len(snapshot.branches),
+            "audit_events_high_water": snapshot.audit_events_high_water,
+        },
+        ts=ts,
+    )
+
+    conn.execute(
+        "INSERT INTO memory_records ("
+        " memory_root, schema_version, parent_memory_root,"
+        " audit_events_high_water, branch_summaries_blob,"
+        " state, audit_event_hash, created_at"
+        ") VALUES (?, ?, ?, ?, ?, 'live', ?, ?)",
+        (
+            root,
+            snapshot.schema_version,
+            snapshot.parent_memory_root,
+            snapshot.audit_events_high_water,
+            body_blob,
+            event_hash,
+            ts,
+        ),
+    )
+
+    for branch in snapshot.branches:
+        digest = branch_digest(branch)
+        conn.execute(
+            "INSERT OR IGNORE INTO memory_branch_summaries ("
+            " branch_id, memory_root, summary_digest, summary_blob, count"
+            ") VALUES (?, ?, ?, ?, ?)",
+            (
+                branch.branch_id,
+                root,
+                digest,
+                branch.summary_blob,
+                int(branch.count),
+            ),
+        )
+
+    return root
+
+
+def load(conn: sqlite3.Connection, root: str) -> Optional[dict]:
+    row = conn.execute(
+        "SELECT memory_root, schema_version, parent_memory_root,"
+        "       audit_events_high_water, branch_summaries_blob,"
+        "       state, audit_event_hash, created_at,"
+        "       falsified_at, falsified_reason"
+        " FROM memory_records WHERE memory_root = ?",
+        (root,),
+    ).fetchone()
+    if row is None:
+        return None
+    return dict(row)
+
+
+def latest(conn: sqlite3.Connection) -> Optional[dict]:
+    row = conn.execute(
+        "SELECT memory_root, schema_version, parent_memory_root,"
+        "       audit_events_high_water, branch_summaries_blob,"
+        "       state, audit_event_hash, created_at,"
+        "       falsified_at, falsified_reason"
+        " FROM memory_records "
+        " WHERE state = 'live' "
+        " ORDER BY created_at DESC LIMIT 1"
+    ).fetchone()
+    if row is None:
+        return None
+    return dict(row)
+
+
+def branches_for(conn: sqlite3.Connection, root: str) -> list[dict]:
+    """Return all branch summaries attached to a memory_root."""
+    rows = conn.execute(
+        "SELECT branch_id, memory_root, summary_digest, summary_blob, count"
+        " FROM memory_branch_summaries"
+        " WHERE memory_root = ?"
+        " ORDER BY branch_id",
+        (root,),
+    ).fetchall()
+    return [dict(r) for r in rows]
diff --git a/docs/TICKETS.md b/docs/TICKETS.md
index d9d4b76..46ca479 100644
--- a/docs/TICKETS.md
+++ b/docs/TICKETS.md
@@ -62,7 +62,7 @@ Newest first. Update on every open/close.
 | #000020  | Capital-cost ledger (8-capital queues)         | closed · landed 2026-05-07 | 2026-05-07 | —         |
 | #000019  | Specification methodology for π* and V         | open · awaiting go/no-go | 2026-05-07 | —         |
 | #000018  | Adversarial soft-hash covert-channel analysis  | open · awaiting go/no-go | 2026-05-07 | —         |
-| #000017  | Memory-root: lifelong learning audit chain     | open · awaiting go/no-go | 2026-05-07 | —         |
+| #000017  | Memory-root: lifelong learning audit chain     | closed · landed 2026-05-07 | 2026-05-07 | —         |
 | #000016  | ZK Phase-2 frontier proof (concretize)         | open · awaiting go/no-go | 2026-05-07 | —         |
 | #000015  | π* domain library + cross-domain composition   | open · awaiting go/no-go | 2026-05-07 | —         |
 | #000014  | SelfModel: schema, falsification, integration  | closed · landed 2026-05-07 | 2026-05-07 | —         |
diff --git a/docs/tickets/ticket-000017-memory-root-lifelong-learning.md b/docs/tickets/ticket-000017-memory-root-lifelong-learning.md
index 754f528..52364d5 100644
--- a/docs/tickets/ticket-000017-memory-root-lifelong-learning.md
+++ b/docs/tickets/ticket-000017-memory-root-lifelong-learning.md
@@ -1,7 +1,8 @@
 # Ticket #000017 — Memory-root: lifelong learning audit chain
 
-**Status:** open · awaiting go/no-go
+**Status:** closed · landed 2026-05-07
 **Opened:** 2026-05-07
+**Closed:** 2026-05-07
 **Scope:** Spec + initial wire-up of a `memory_root` commitment that
 binds an arborist-hosted agent's evolving cross-query memory into the
 audit chain. Distinct from per-query providence cache (which is keyed
@@ -247,12 +248,41 @@ claims X" to "agent's behavior history when claim was made."
 
 ## 6. Status
 
-**Open · awaiting go/no-go.** Smaller surface than SelfModel
-(ticket #000014); could land standalone or batched with #000014
-since they reference each other. Recommended sequence: #000014
-first (identity), then #000017 (history) since SelfModel optionally
-cites memory_root.
+**Closed 2026-05-07.** Scope delivered:
 
-Closure criterion: schema lands, `arborist memory snapshot`
-produces a deterministic memory_root, branch projections covered
-by tests, audit chain stays clean.
+- Schema migration `_migrate_memory_root` adds `memory_records` +
+  `memory_branch_summaries` tables. Sibling state — does NOT enter
+  cache_key by default (per §2.4 advisory mode).
+- Module `arborist.memory`:
+  - `canonical.py` — `MemorySnapshot` + `BranchSummary` dataclasses,
+    `branch_digest`, `memory_root` SHA-256 derivation. Branch order
+    invariant (sorted by branch_id before hashing).
+  - `projections.py` — three deterministic projections at v1:
+    `failure-motif:violations`, `audit-mode-distribution`,
+    `falsification-state`. Projection rule version pinned via
+    `PROJECTION_VERSION = "projections-v1"`.
+  - `snapshot.py` — `snapshot(conn)` runs default branch set against
+    current state, returns a `MemorySnapshot`. Side-effect-free.
+  - `store.py` — `store_snapshot` persists + emits
+    `memory_snapshot_landed` audit event. Idempotent on same root.
+  - `falsify.py` — `falsify` and `mark_stale` flip state and emit
+    `memory_falsified` / `memory_marked_stale` audit events.
+- CLI: `arborist memory snapshot|show|branches|falsify`.
+- SelfModel integration (ticket #000014 already shipped): SelfModel
+  snapshot reads the latest live memory_root and folds it into the
+  SelfModel canonical body. SelfModel root therefore changes when
+  memory_root changes.
+- Tests: `tests/test_memory_root.py` — 15 cases covering canonical
+  body stability, root invariance under branch order, snapshot
+  determinism + high-water progression, store idempotency,
+  falsify/mark_stale, projection determinism, audit-chain integrity.
+  Full suite: 1040 passed, 36 skipped.
+
+Out-of-scope items (deferred to follow-ups):
+
+- Cascade re-evaluation (`arborist memory cascade`). Memory
+  falsification stays advisory (option B in §2.3); explicit
+  cascade is a follow-up.
+- Cross-shard memory reconciliation. Per-shard for now.
+- Memory-driven retrieval routing.
+- Fork inheritance (mesh / v8 concern).
diff --git a/tests/test_memory_root.py b/tests/test_memory_root.py
new file mode 100644
index 0000000..15b4dd2
--- /dev/null
+++ b/tests/test_memory_root.py
@@ -0,0 +1,325 @@
+"""Memory-root tests (ticket #000017).
+
+Covers:
+- canonical body and memory_root SHA-256 derivation
+- branch_digest stability under repeated input
+- branch sort-order invariance
+- snapshot determinism on same store state
+- store_snapshot idempotency
+- falsify and mark_stale audit events + state transitions
+- audit chain stays clean across memory ops
+"""
+
+from __future__ import annotations
+
+import hashlib
+
+import pytest
+
+from arborist.memory import (
+    BranchSummary,
+    MemorySnapshot,
+    branch_digest,
+    branches_for,
+    canonical_branches_blob,
+    falsify,
+    latest,
+    load,
+    mark_stale,
+    memory_root,
+    snapshot,
+    store_snapshot,
+)
+from arborist.memory.canonical import SCHEMA_VERSION
+from arborist.memory.projections import (
+    DEFAULT_BRANCHES,
+    PROJECTION_VERSION,
+    project_failure_motif_violations,
+)
+from arborist.store import append_audit, connect, latest_event_hash, transaction
+
+
+# --- canonical ---------------------------------------------------------
+
+
+def _branch(branch_id: str, body: bytes, count: int) -> BranchSummary:
+    return BranchSummary(
+        branch_id=branch_id, summary_blob=body, count=count
+    )
+
+
+def test_branch_digest_stable():
+    a = _branch("b", b"hello", 3)
+    b = _branch("b", b"hello", 3)
+    assert branch_digest(a) == branch_digest(b)
+
+
+def test_branch_digest_changes_on_content():
+    a = _branch("b", b"hello", 3)
+    b = _branch("b", b"helloo", 3)
+    assert branch_digest(a) != branch_digest(b)
+
+
+def test_memory_root_invariant_under_branch_order():
+    snap_a = MemorySnapshot(
+        schema_version=SCHEMA_VERSION,
+        parent_memory_root=None,
+        audit_events_high_water="genesis",
+        branches=(_branch("a", b"x", 1), _branch("b", b"y", 2)),
+    )
+    snap_b = MemorySnapshot(
+        schema_version=SCHEMA_VERSION,
+        parent_memory_root=None,
+        audit_events_high_water="genesis",
+        branches=(_branch("b", b"y", 2), _branch("a", b"x", 1)),
+    )
+    assert memory_root(snap_a) == memory_root(snap_b)
+
+
+def test_memory_root_changes_when_high_water_changes():
+    snap_a = MemorySnapshot(
+        schema_version=SCHEMA_VERSION,
+        parent_memory_root=None,
+        audit_events_high_water="0xa",
+        branches=(),
+    )
+    snap_b = MemorySnapshot(
+        schema_version=SCHEMA_VERSION,
+        parent_memory_root=None,
+        audit_events_high_water="0xb",
+        branches=(),
+    )
+    assert memory_root(snap_a) != memory_root(snap_b)
+
+
+# --- snapshot ----------------------------------------------------------
+
+
+def test_snapshot_builds_default_branches_on_empty(tmp_path):
+    db = tmp_path / "shard.db"
+    conn = connect(db)
+    try:
+        with transaction(conn):
+            ms = snapshot(conn)
+        assert ms.schema_version == SCHEMA_VERSION
+        # Default branch set produces three summaries.
+        ids = sorted(b.branch_id for b in ms.branches)
+        assert "audit-mode-distribution" in ids
+        assert "failure-motif:violations" in ids
+        assert "falsification-state" in ids
+    finally:
+        conn.close()
+
+
+def test_snapshot_deterministic_same_state(tmp_path):
+    db = tmp_path / "shard.db"
+    conn = connect(db)
+    try:
+        with transaction(conn):
+            a = snapshot(conn)
+            b = snapshot(conn)
+        assert memory_root(a) == memory_root(b)
+    finally:
+        conn.close()
+
+
+def test_snapshot_picks_up_new_audit_events(tmp_path):
+    db = tmp_path / "shard.db"
+    conn = connect(db)
+    try:
+        with transaction(conn):
+            a = snapshot(conn)
+            r1 = memory_root(a)
+            append_audit(
+                conn,
+                event_type="providence_write",
+                subject_root="00" * 32,
+                body={"audit_mode": "STRICT", "violations": []},
+            )
+            b = snapshot(conn)
+            r2 = memory_root(b)
+        assert r1 != r2  # high-water shifted
+    finally:
+        conn.close()
+
+
+# --- store_snapshot ---------------------------------------------------
+
+
+def test_store_snapshot_persists_and_emits_audit(tmp_path):
+    db = tmp_path / "shard.db"
+    conn = connect(db)
+    try:
+        with transaction(conn):
+            ms = snapshot(conn)
+            root = store_snapshot(conn, ms)
+        loaded = load(conn, root)
+        assert loaded is not None
+        assert loaded["state"] == "live"
+
+        ev = conn.execute(
+            "SELECT 1 FROM audit_events "
+            "WHERE event_type='memory_snapshot_landed' AND subject_root = ?",
+            (root,),
+        ).fetchone()
+        assert ev is not None
+
+        # Branch rows present.
+        rows = branches_for(conn, root)
+        ids = {r["branch_id"] for r in rows}
+        assert "audit-mode-distribution" in ids
+        assert "falsification-state" in ids
+    finally:
+        conn.close()
+
+
+def test_store_snapshot_idempotent(tmp_path):
+    db = tmp_path / "shard.db"
+    conn = connect(db)
+    try:
+        with transaction(conn):
+            ms = snapshot(conn)
+            r1 = store_snapshot(conn, ms)
+            r2 = store_snapshot(conn, ms)
+        assert r1 == r2
+        n = conn.execute(
+            "SELECT COUNT(*) FROM audit_events "
+            "WHERE event_type='memory_snapshot_landed' AND subject_root = ?",
+            (r1,),
+        ).fetchone()[0]
+        assert n == 1
+    finally:
+        conn.close()
+
+
+def test_latest_returns_most_recent(tmp_path):
+    db = tmp_path / "shard.db"
+    conn = connect(db)
+    try:
+        with transaction(conn):
+            ms1 = snapshot(conn)
+            r1 = store_snapshot(conn, ms1, ts=1700000000)
+            # Force a different snapshot via an audit event then re-snap.
+            append_audit(
+                conn,
+                event_type="providence_write",
+                subject_root="00" * 32,
+                body={"audit_mode": "HYBRID", "violations": ["X"]},
+            )
+            ms2 = snapshot(conn)
+            r2 = store_snapshot(conn, ms2, ts=1700000100)
+        live = latest(conn)
+        assert live["memory_root"] == r2
+        assert r1 != r2
+    finally:
+        conn.close()
+
+
+# --- falsify / mark_stale ---------------------------------------------
+
+
+def test_falsify_flips_state(tmp_path):
+    db = tmp_path / "shard.db"
+    conn = connect(db)
+    try:
+        with transaction(conn):
+            ms = snapshot(conn)
+            root = store_snapshot(conn, ms)
+            event_hash = falsify(
+                conn,
+                root,
+                reason="motif drift",
+                triggering_branch_id="failure-motif:violations",
+            )
+        loaded = load(conn, root)
+        assert loaded["state"] == "falsified"
+        assert event_hash != ""
+    finally:
+        conn.close()
+
+
+def test_falsify_idempotent(tmp_path):
+    db = tmp_path / "shard.db"
+    conn = connect(db)
+    try:
+        with transaction(conn):
+            ms = snapshot(conn)
+            root = store_snapshot(conn, ms)
+            falsify(conn, root, reason="r1")
+            second = falsify(conn, root, reason="r2")
+        assert second == ""
+    finally:
+        conn.close()
+
+
+def test_mark_stale_terminal_under_falsified(tmp_path):
+    db = tmp_path / "shard.db"
+    conn = connect(db)
+    try:
+        with transaction(conn):
+            ms = snapshot(conn)
+            root = store_snapshot(conn, ms)
+            falsify(conn, root, reason="hard")
+            second = mark_stale(conn, root, reason="soft")
+        assert second == ""
+        assert load(conn, root)["state"] == "falsified"
+    finally:
+        conn.close()
+
+
+# --- projection determinism -------------------------------------------
+
+
+def test_projection_violations_deterministic(tmp_path):
+    db = tmp_path / "shard.db"
+    conn = connect(db)
+    try:
+        with transaction(conn):
+            for tag in ["TITLE_MISMATCH", "TITLE_MISMATCH", "WARRANT_MISSING"]:
+                append_audit(
+                    conn,
+                    event_type="providence_write",
+                    subject_root=None,
+                    body={"audit_mode": "HYBRID", "violations": [tag]},
+                )
+        s1, _ = project_failure_motif_violations(conn)
+        s2, _ = project_failure_motif_violations(conn)
+        assert s1.summary_blob == s2.summary_blob
+        assert s1.count == s2.count == 3
+        # Decoded body has expected counts.
+        import json
+
+        body = json.loads(s1.summary_blob.decode("utf-8"))
+        assert body["projection_version"] == PROJECTION_VERSION
+        assert body["tag_counts"]["TITLE_MISMATCH"] == 2
+        assert body["tag_counts"]["WARRANT_MISSING"] == 1
+    finally:
+        conn.close()
+
+
+# --- audit chain ------------------------------------------------------
+
+
+def test_audit_chain_stays_clean(tmp_path):
+    db = tmp_path / "shard.db"
+    conn = connect(db)
+    try:
+        with transaction(conn):
+            ms = snapshot(conn)
+            root = store_snapshot(conn, ms)
+            falsify(conn, root, reason="r")
+        rows = conn.execute(
+            "SELECT event_hash, prev_event_hash, body "
+            "FROM audit_events ORDER BY seq"
+        ).fetchall()
+        prev = None
+        for r in rows:
+            h = hashlib.sha256()
+            if prev is not None:
+                h.update(bytes.fromhex(prev))
+            h.update(r["body"].encode("utf-8", errors="surrogatepass"))
+            assert h.hexdigest() == r["event_hash"]
+            prev = r["event_hash"]
+        assert prev == latest_event_hash(conn)
+    finally:
+        conn.close()