memory: land ticket #000017 (memory-root lifelong learning summary)

Periodic, deterministic projection over audit_events that summarizes
recurring failure motifs, audit-mode distribution, and falsification
state. Sibling layer to providence_cache (per-cache_key answers) and
audit_events (per-event chain) — memory_root is the cross-query
behavior history a SelfModel optionally cites.

Surface:

- arborist.memory.{canonical,projections,snapshot,store,falsify}
- Three default branch projections at v1 (PROJECTION_VERSION pin):
  - failure-motif:violations (counts violation tags from
    providence_write events)
  - audit-mode-distribution (STRICT/HYBRID/UNGROUNDED counts)
  - falsification-state (current cache state distribution)
- memory_root = SHA-256 over canonical body bytes; sort-invariant
  on branches.
- CLI: arborist memory snapshot|show|branches|falsify
- Audit events: memory_snapshot_landed, memory_falsified,
  memory_marked_stale.

SelfModel integration: arborist.selfmodel.snapshot reads latest live
memory_root and folds into SelfModel body. Already shipped in #000014;
this ticket completes the round-trip (memory shifts → SelfModel root
shifts).

Tests: tests/test_memory_root.py (15 cases). Full suite: 1040 passed,
36 skipped.

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 | —         |

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).