[search results] Score every vector search by cosine similarity, and name scores for it (port of #1598's cosine half) - #1663

…ck) (MemMachine#1606)

* Regenerate the OpenAPI document under the locked FastAPI

`docs/openapi.json` predates the FastAPI release in `uv.lock`
(0.141.1), whose `ValidationError` component carries `input` and `ctx`;
regenerating the document with `docs/tools/generate_openapi.py` adds the
two fields and changes nothing else. Separate from the API changes above
it so their diffs of this file show only what they change.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

* Remove per-project filterable properties

A project could declare `properties_schema`, a set of caller property keys
with types, on its long-term memory configuration; the event backend merged
it into the vector store collection's indexed schema and rejected filters on
any other `m.<key>`. That let a tenant create database resources (indexes,
columns) by naming them in a request, which is what forced per-collection
native resources named by a hash of their schema on the backends that limit
them.

The option is removed from the server configuration, the project API and
the memory-configuration API, the Python SDK, the sample configurations,
the configuration docs and the OpenAPI document. A filter may name any
`m.<key>`; the stores evaluate it on the properties they hold. What a store
indexes is decided by the deployment, not per project.

A breaking API change on `speedkick`.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

Rebased onto MemMachine#1631: the per-project schema also leaves MemMachine#1631's service
locator, which creates the session's collection in a retry loop, and the
commented option goes from the event sample configuration MemMachine#1698 added.

---------

Co-authored-by: Claude Opus 5 (1M context) <[email protected]>
(cherry picked from commit a8322a7)

…res' lookup to get_partition

A vector store's logical collection becomes a partition, the segment
store's word for the same thing, and both stores' lookup is get_partition,
answering None like a Python get. Identifiers only, produced by the script
below; the (namespace, name) identity, the per-partition config and every
docstring are as they were, and the next change gives them their meaning.
The native clients' create_collection and delete_collection keep their
names.

The vocabulary also reaches what sits under the rename: the registry
package, its modules, classes and tables, the `collection_registry` option
of a Qdrant or Milvus backend and the store parameter and attribute that
carry it (`partition_registry`), the stale-handle and pending errors, the
registry-backed base and its handle lookup, the purge method
(`purge_deleted_partitions`, the segment store's name for it) and
open-or-create.

```sh
set -e
cd "$(git rev-parse --show-toplevel)"
git mv packages/server/server_tests/memmachine_server/common/vector_store/in_memory_vector_store_collection.py \
       packages/server/server_tests/memmachine_server/common/vector_store/in_memory_vector_store_partition.py
git mv packages/server/server_tests/memmachine_server/common/vector_store/collection_lifecycle_contract.py \
       packages/server/server_tests/memmachine_server/common/vector_store/partition_lifecycle_contract.py
git mv packages/server/src/memmachine_server/common/vector_store/collection_registry \
       packages/server/src/memmachine_server/common/vector_store/partition_registry
git mv packages/server/src/memmachine_server/common/vector_store/partition_registry/collection_registry.py \
       packages/server/src/memmachine_server/common/vector_store/partition_registry/partition_registry.py
git mv packages/server/src/memmachine_server/common/vector_store/partition_registry/sqlalchemy_collection_registry.py \
       packages/server/src/memmachine_server/common/vector_store/partition_registry/sqlalchemy_partition_registry.py
git mv packages/server/server_tests/memmachine_server/common/vector_store/collection_registry \
       packages/server/server_tests/memmachine_server/common/vector_store/partition_registry
git mv packages/server/server_tests/memmachine_server/common/vector_store/partition_registry/test_sqlalchemy_collection_registry.py \
       packages/server/server_tests/memmachine_server/common/vector_store/partition_registry/test_sqlalchemy_partition_registry.py
git ls-files -z 'packages/server/*.py' 'docs/*.mdx' 'sample_configs/*.sample' 'sample_configs/*.yml' 'deployments/helm/templates/*.yaml' | xargs -0 perl -0pi -e '
  s/VectorStoreCollection(?!Config)/VectorStorePartition/g;
  s/in_memory_vector_store_collection/in_memory_vector_store_partition/g;
  s/collection_lifecycle_contract/partition_lifecycle_contract/g;
  s/CollectionLifecycleContract/PartitionLifecycleContract/g;
  s/collection_registry/partition_registry/g;
  s/SQLAlchemyCollectionRegistry/SQLAlchemyPartitionRegistry/g;
  s/CollectionRegistry/PartitionRegistry/g;
  s/RegisteredCollection/RegisteredPartition/g;
  s/get_registered_collection/get_registered_partition/g;
  s/_build_collection_handle/_build_partition_handle/g;
  s/\bCollectionT\b/PartitionT/g;
  s/register_collection\b/register_partition/g;
  s/\b_Collection\b/_Partition/g;
  s/CollectionRow/PartitionRow/g;
  s/vector_store_collection(?!_schema|_namespace)/vector_store_partition/g;
  s/open_or_create_collection/open_or_create_partition/g;
  s/open_collection/get_partition/g;
  s/_purge_deleted_collections_forever/_purge_deleted_vector_store_partitions_forever/g;
  s/purge_deleted_collections/purge_deleted_partitions/g;
  s/def create_collection\(/def create_partition(/g;
  s/def delete_collection\(/def delete_partition(/g;
  s/\.create_collection\((\s*namespace=)/.create_partition($1/g;
  s/\.delete_collection\((\s*namespace=)/.delete_partition($1/g;
  s/\.create_collection(?=\s*=\s*AsyncMock|\.assert_|\.side_effect|\.await_count)/.create_partition/g;
  s/\.delete_collection(?=\s*=\s*AsyncMock|\.assert_|\.side_effect|\.await_count)/.delete_partition/g;
  s/"create_collection"/"create_partition"/g;
  s/"delete_collection"/"delete_partition"/g;
  s/"open_or_create_collection"/"open_or_create_partition"/g;
  s/only delete_collection is invoked/only delete_partition is invoked/g;
  s/test_delete_collection_/test_delete_partition_/g;
  s/open_partition/get_partition/g;
  s/(vector_store_partition \(VectorStorePartition\):\n\s+)Vector store collection\./$1Vector store partition./g;
'
uv run ruff check --fix --quiet packages/server
uv run ruff format --quiet packages/server
```

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

…uilt by the composition root

A vector store was a factory of logical collections, each identified by
a (namespace, name) pair and created with its own dimensions, metric and
schema; Qdrant and Milvus shared one native collection among logical
collections of equal configuration, under a name derived from a hash of
that configuration, and the registry mapped (namespace, name) to it.

A store is now one collection: `VectorStore(vector_store_name,
vector_dimensions, similarity_metric, indexed_properties)` names its one
native collection (or its tables and index files) at construction, every
partition of it shares the store's dimensions, metric and schema, and
`provision()` creates the store's durable resources idempotently, before
`startup`. `create_partition(key)`, `open_or_create_partition(key)`,
`get_partition(key)` and `delete_partition(key)` take a string key; a
partition is the records carrying its incarnation in the store's native
collection (Qdrant, Milvus) or a pair of tables (the SQLite stores), and
the registry records what each partition was created under, so a store
built with other dimensions, another metric or another schema raises
`VectorStorePartitionSchemaMismatchError` instead of reading columns and
vectors that are not there. "Collection" names only the native Qdrant or
Milvus collection. Vector store names match `[a-z0-9_]+` and are at most
32 bytes, the rule partition and property keys follow, so every name
works on every backend: the Qdrant store names its collection by the
vector store name, and the Milvus store by `sys_` followed by it, since
Milvus requires a leading letter or underscore and names its own
internals with a leading underscore. The hash-derived native names go,
and with them the per-partition config.

The partition registry is keyed by partition key within one store: its
tables, `partition_registry_pt` and `partition_registry_gc`, are shared
by every store on a database and keyed by vector store name, so the
registries of several stores share one database and nothing else.
`mark_live` and `unregister_incarnation` take the incarnation alone. On
the registry-backed base, the storage a store's partitions share is
prepared by `provision()` (`_prepare_storage()`), and the storage a
partition keeps of its own by `_prepare_partition_storage(key,
incarnation)`, between its registration and its mark; the Qdrant and
Milvus stores keep nothing per partition. A purge round works on one
incarnation in the store's own collection.

`DatabaseManager.get_vector_store(backend, vector_store_name=,
vector_dimensions=, similarity_metric=, indexed_properties=)` builds and
caches one store per (backend, vector store name), provisioning its
registry and then the store; asking for a name again with other
dimensions, another metric or other keys is a
`VectorStoreConfigurationError`. The event backend's store is named by a
UUIDv5 of its embedder id in the UUIDv5 of its backend's key in a namespace
fixed for the event backend, written as 32 hexadecimal digits, so neither
the key nor the id is constrained; stores on different backends never share
a name, so their registries stay apart when the backends share a registry
database, since a store name identifies one store among all the stores
whose registries share it.
Semantic memory's one store is named `semantic_memory` whatever its
embedder and holds every org's features in one partition,
`semantic_memory`, as main's one collection does.
The event backend opens a session's partition with
`open_or_create_partition`, which waits on one another worker is still
creating.

The SQLite stores change shape only: their registry tables become
`vector_store_sqlite_pt` and `vector_store_sqlite_vec_pt`, keyed by
vector store name and partition key, the pending-operation log is keyed
the same way, and per-partition table names embed the vector store name.
No migration is provided; existing SQLite vector data is orphaned.

Rebuilt as one change on MemMachine#1631: this PR's earlier history carried copies
of MemMachine#1631's commits as of `38684b385`, its own commits on them, and
mirrors of MemMachine#1631's later commits in its terms. Its code is that history's
final tree, which was verified, merged with main and without MemMachine#1624's
commits. The design documents are still MemMachine#1631's and describe collections.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

…up, not a separate provision

A vector store and its partition registry each had a provision() that
created their durable resources, run by the composition root before
startup(). The split between provisioning a store and starting it is
MemMachine#1570's to make for every store at once, so here startup() does both
again, as on main: a store's startup prepares the storage its
partitions share (the native collection and its indexes, or the SQLite
tables), and the registry's startup creates its tables, as MemMachine#1631's does.
The database manager starts the registry, then the store.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

…er, live from resolve

The registry is addressed by partition key only. `register(key, schema)`
answers a PendingRegistration, whose `mark_live()` answers the same life
as a LiveRegistration or raises VectorStorePartitionDeletedError when the
partition was deleted meanwhile, and whose `unregister()` abandons that
life alone. `resolve(key)` answers the LiveRegistration of the live
partition, None when there is none, and raises
VectorStorePartitionPendingError, which now carries the pending
partition's schema, when it is pending. A LiveRegistration's
`require_current()` raises VectorStorePartitionHandleStaleError once its
partition is deleted. `get`, `mark_live(incarnation)`,
`unregister_incarnation` and RegisteredPartition are gone, so deletion is
by key or by a pending registration, never through a live one. The
SQLAlchemy registry supplies frozen-dataclass registrations holding the
engine and the vector store name, and a module function runs the
unregistration transaction.

The base handle takes its live registration, fences on
`require_current()`, and `_partition_handle` builds a handle from one.
`create_partition` lets VectorStorePartitionDeletedError propagate, and
the VectorStore interface names it; open-or-create catches it and creates
again, refuses a pending partition of another schema at once from the
pending error's schema, and re-raises the last pending error. A
`get_partition` of a pending partition of another schema still reports the
mismatch first. The Qdrant and Milvus handles take the registration in
place of the key, the incarnation and the registry lookup.

Tests follow: the registry's tests answer registrations and gain one for
`require_current`; the base's tests patch the pending registration type's
`unregister` and expect the deleted error from a creation a deletion
undid; the lifecycle contract patches the live registration type's
`require_current`, registers its racing winners through pending
registrations, and counts the deleted error among churn's outcomes; the
Qdrant and Milvus tests that build a handle on a mocked client give it a
registration that stays current.

The same change as MemMachine#1734's 735c649, f88aaa8, e25be60 and
b2bb2d8 and the handle halves of MemMachine#1735's 9096edd and MemMachine#1736's
5582cf4, for this PR's partition registry. The event-backend locator
change has no counterpart: the locator here opens its partition with
open-or-create, which creates again itself.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

…nd their partitions

The design documents came from MemMachine#1733-MemMachine#1736, where a store holds logical
collections addressed by namespace and name, each with its own
configuration. Here a store is one collection, with its dimensions, metric
and declared schema fixed at construction, and a partition is one tenant's
records in it, addressed by key. The documents say so:

- the collection registry document becomes the partition registry
  document: a registry belongs to one store and is addressed by partition
  key; its tables are `partition_registry_pt` and `partition_registry_gc`,
  and a tombstone needs no location, since the incarnation alone finds a
  dead partition's records in the store's native collection; a partition
  created under another schema is refused; `startup` creates the tables, as
  every store's startup creates its durable resources; a decision records
  that a store is one collection;
- the Qdrant and Milvus documents lay out one native collection per store,
  named by the vector store name (`sys_` and the name on Milvus), created at
  startup, where a partition's creation makes nothing in the backend;
- the overview, isolation, consistency and purge documents speak of
  partitions, `purge_deleted_partitions` and `settle(partition)`, and the
  overview describes the store and its partitions.

The measurements and their conditions are unchanged.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

…gistration

PendingRegistration and LiveRegistration named the partition's state when
the registry answered them, which a deletion by anyone falsifies: a "live"
registration may have been deleted since. What does not change is what
each handle's holder may do, so the handles are named for that, in the
words of two known patterns: Try-Confirm/Cancel for the creator, and the
stale handle for everyone else.

- `register` is `reserve`, and answers a `Reservation`: the creator's hold
  on the key while it prepares the partition's storage.
- `PendingRegistration.mark_live` is `Reservation.confirm`, which marks the
  partition live and answers its `Registration`.
- `PendingRegistration.unregister` is `Reservation.cancel`.
- `LiveRegistration` is `Registration`; `resolve`, `require_current` and
  `unregister(partition_key)` keep their names.
- The fields both share sit in a private base, `_RegistryEntry`.

"Pending" stays the word for the partition's state, in the store contract
and VectorStorePartitionPendingError. The base store's creation flow, its
task set and log text, the Qdrant and Milvus handles, the tests and the
design documents follow; the registry design records why the names are
roles.

The same change as MemMachine#1734's ffa954c, MemMachine#1735's 87edbad and MemMachine#1736's
8e65391, for this PR's partition registry.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

…ain open-or-create's give-up

Two review changes to MemMachine#1734's registry and base store, for this PR's
partitions:

- `Reservation.cancel()` acts only while the partition is pending, as
  `confirm()` does. A creator whose confirmation committed but whose
  answer was lost, and which then cancels, leaves the live partition
  alone: only a deletion by key ends it. The registry contract, the
  SQLAlchemy registry and the registry design document say so, and a
  test cancels after a confirmation.
- Open-or-create's `VectorStoreAttemptsExhaustedError` is raised from the
  race it last lost, the last `VectorStorePartitionAlreadyExistsError` or
  `VectorStorePartitionDeletedError` it caught. A partition that stays
  pending still raises the pending error itself. A base-store test checks
  the cause.

The same changes as MemMachine#1734's 9daf7e7 and 93a85da, for this PR's
partition registry.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

…1734's other review changes

MemMachine#1734's latest review changes, for this PR's partition registry and stores:

- `run_purge_round(purge_round)` replaces `claim_purgeable_incarnation()`.
  The registry claims the oldest due tombstone, calls the round with its
  incarnation inside the claim's transaction, and records what the round
  returns. `PurgeClaim` and its `any_records_found` guard go; `PurgeRound`
  takes only the incarnation, since a tombstone here carries nothing else.
  On SQLite the claim is an `UPDATE ... RETURNING` of the oldest eligible
  row, so purgers serialize at the claim; PostgreSQL keeps `FOR UPDATE SKIP
  LOCKED`. A failure count at or past the dead-letter bound is reported.
- A reservation's cancel reports its own failure from its task, so a
  creation cancelled again still has the failure logged.
- `get_partition` runs under the tracker like the other lifecycle calls,
  and the SQLite stores check partition keys with the shared
  `require_partition_key`.
- The registry and purge documents follow. The upgrade notes state what
  holds for these stores: they name their native collections by vector
  store name, which no earlier release did, so an existing Qdrant or Milvus
  collection is never read or purged, and can be dropped before or after
  upgrading. The Milvus design document's consequence, which said an
  existing collection has to be dropped, says the same, and the Helm
  README lists `partition_registry` among the Qdrant store's keys.

The same changes as MemMachine#1734's d041785, cd13045, 35b57b7, 0a68f37,
d05556b, 118d23b, 5225933 and 783967e, MemMachine#1735's a40bc50 and
MemMachine#1736's caefa7b, for this PR's partitions.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

…r is cancelled

A creation cancelled its reservation only when preparing the partition's
storage raised. A confirmation that raised, or a creation cancelled while
it confirmed, left the partition pending until someone deleted it.

The base store's creation step now prepares the storage and confirms the
reservation together, and cancels the reservation if either raises or the
creation is cancelled, shielded as before; the cancel's task reports its
own failure. The cancel acts only on a pending partition, so a
confirmation that committed before its failure was observed stands.
create_partition and open-or-create both go through it; open-or-create
still takes a confirmation's VectorStorePartitionDeletedError as a race to
create again. Base-store tests cover a failed confirmation, a cancelled
one, and one that committed before failing. The registry design document
says so, and the purge document says which writers wait on SQLite's lock
during a purge round.

The same changes as MemMachine#1734's f4c585e and 4dde7c8, for this PR's
partitions.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

…saction across the round

A purge round ran inside the claim's transaction: on PostgreSQL a row lock
held idle while the backend deleted, and on SQLite the database file's write
lock, which every store sharing the file waited on for the whole round.

- The claim is a lease. One committed `UPDATE ... RETURNING` takes the
  oldest due tombstone that no unexpired claim holds, stamping `claimed_at`
  and incrementing `claim_generation`; the round runs with no transaction
  open; the writes that end the claim are conditioned on its generation, so
  a round that outlasted its lease cannot end the claim taken after it. A
  round that found nothing removes the tombstone under any claim.
  `purge_lease_seconds` (default 300) sets the lease.
- A claim that finds the previous claim unended past its lease runs no
  round: it counts that round as failed, as of when it was claimed, and
  logs it. A cancelled round ends its claim uncounted, in a shielded write
  whose task reports its own failure.
- `purge_retry_backoff_seconds` is `base_purge_retry_backoff_seconds`, the
  first delay the backoff doubles.
- The registry refuses an engine on StaticPool or in-memory SQLite, whose
  connections do not arbitrate as separate transactions; the wiring tests
  give their registry a file database.

The registry tests cover the lease, the outcome writes and their fence,
deletion and reservation atomicity under injected faults, two registries
sharing a database, collision without waiting, churn across engines, and
random operation sequences against a model. The purge and registry design
documents describe the lease and the alternatives considered.

The same changes as MemMachine#1734's f1e9de8, 054b079, a4e2b24 and 900a926,
MemMachine#1735's 3d7761e and 81b1bf5, and MemMachine#1736's 1b94f7f, for this PR's
partition registry.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

The query contract said nothing of a match scoring exactly the threshold,
and Qdrant dropped it: the server compares its threshold in single precision
and keeps only scores strictly better than it.

The contract now says a match scoring exactly the threshold is returned.
The Qdrant store sends the server the adjacent single-precision value on
the worse side, and applies the caller's threshold exactly itself; a
threshold beyond single precision is not sent. Both SQLite stores already
keep the match, and each now tests it on every metric it supports.

The same changes as MemMachine#1735's ccba117 and 6bbc131, for this PR's stores.
MemMachine#1736's cc29d27, Milvus's test of the same, is ported with the store
tests.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

…cycle contract's drain

MemMachine#1735's and MemMachine#1736's latest tests, for this PR's partitions:

- Every Qdrant store test runs against a Qdrant server, over REST and gRPC:
  local mode ignores payload indexes and raises its own exceptions where a
  server answers not-found or already-exists, so it is no longer a fixture.
  The tests on a mocked client stay in the default suite.
- Both stores gain tests that partitions and stores of different names keep
  their records apart, that purge rounds reclaim a write landing after a
  round and drain two stores' tombstones alone, that ranking, scores and the
  threshold follow every similarity metric, that a point or entity the
  server refuses on its own raises, that concurrent creations and startups
  agree, that two stores churning one registry keep every partition exact,
  and that seeded operation sequences, and on Milvus random filters, agree
  with a model. The Milvus tests also pin its read consistency and its
  settings with values other than their defaults.
- The lifecycle contract's drain fails after a bounded number of rounds, it
  settles before checking that a new life is empty, and it checks a stale
  upsert by what the partition holds rather than by its registry reads.

The same changes as MemMachine#1735's 30c30f4, e9e71b5, 6c2362b, 4d3241c,
836db21, 252bcd2, 5e8c049, ef8d3ab, 276a034, 4fb5bd4 and
2aabd3d, and MemMachine#1736's 509c235, 7f1eb3b, 6e312e0, 6d1ed1e,
25e7948, 6f36877, d43e9e6, 6dfbf59 and cc29d27, for this PR's
partitions.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

The base store's purge contract says a round that finds the incarnation's
storage missing returns False, but neither store's round checked: once its
native collection was dropped from outside, every round on it raised,
counted against the tombstone, and dead-lettered it after ten.

A Qdrant round that the server answers not found, over REST or gRPC, and a
Milvus round that finds no native collection, now return False: the
collection is gone with everything in it, so the tombstone is retired. Each
store has a test that drops its native collection and drains the purge.

The same handling as MemMachine#1735's and MemMachine#1736's stores, whose rounds already
checked for a missing native collection; MemMachine#1736's 2575af0 tests it.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

…n, and use serial commas

MemMachine#1734's, MemMachine#1735's, and MemMachine#1736's latest round, for this PR's partition registry
and stores; no behavior changes:

- The queue's `failed_rounds` column is `consecutive_failed_rounds`, in the
  code, the tests, the documents, and the dead-letter log's hint.
- The registry keeps its durations as seconds. `_has_elapsed(seconds,
  since=)` answers whether a duration has passed on the database clock, for
  the retention, the backoff, and the lease, and
  `_purge_retry_backoff_seconds()` computes each tombstone's capped backoff.
- `run_purge_round` runs named steps: `_claim_oldest_due_tombstone` answers a
  `_TombstoneClaim`, an `_UnendedPurgeRound`, or None, and the round's
  outcome goes to `_count_failed_purge_round`,
  `_end_tombstone_claim_after_cancellation`, or `_record_purge_round`.
  `_insert` is `_insert_pending_partition`, `_claim_releases`
  `_tombstone_claim_endings`, and the base store's `_cancellations`
  `_reservation_cancellations`.
- The Milvus filter helpers are named for what they produce, comments are
  shorter, and lists in the documents, comments, and docstrings take a
  serial comma.

The same changes as MemMachine#1734's 2a3d87c and 503687c, MemMachine#1735's 106e106, and
MemMachine#1736's 3681d09 and bc6d4f9, for this PR's partitions.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

A round that never ended was counted by the next claim, which took a
CASE-shaped update that both recorded the lost round and ended its claim;
the count lived apart from the claims that made it.

Each claim now counts its attempt: the claim is a plain update that
increments `consecutive_attempts` (renamed from `consecutive_failed_rounds`),
stamps `claimed_at`, and bumps the generation, and `_TombstoneClaim.attempt`
carries the count. A tombstone is claimable when it has no attempts, when no
claim is open and the backoff has passed since its last failure, or when an
open claim has outlived its lease plus the backoff. A raised round ends its
claim and stamps `last_failed_at`; a cancelled round ends its claim and takes
its attempt back; a round that found records resets the attempts. After
`_MAX_PURGE_ATTEMPTS` attempts a tombstone is dead-lettered, and a last
attempt that raises is reported. A retry logs which attempt it is, and a
raised round's error names its incarnation and attempt. The registry tests,
the purge design document, and the registry design document follow.

The same change as MemMachine#1734's 1732038, for this PR's partition registry.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

`consecutive_attempts` counted the purge rounds claimed since a round last
found records, but its name said only that they were in a row. It is
`attempts_without_progress`, and `_MAX_PURGE_ATTEMPTS` is
`_MAX_PURGE_ATTEMPTS_WITHOUT_PROGRESS`. The column's comment, the claim's
attempt, the backoff parameter's description, the dead-letter log, the
class docstring, the tests, the purge design document, and the registry
design document's table follow; nothing else changes.

The same change as MemMachine#1734's 96a8b5b, for this PR's partition registry.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

…urrent claim

The measured cost of the claim came from earlier forms of it, which held a
transaction across the round. The section now gives the figures measured on
2026-10-06 against the claim this registry ports, naming the MemMachine#1734 commits
they were taken at: the backoff scan with 1k, 10k, and 100k tombstones
backing off, and interactive throughput and liveness latency beside two
sweepers on PostgreSQL and on SQLite.

The same change as MemMachine#1734's bab379b, for this PR's purge document.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

MemMachine#1736's review round, for this PR's Milvus store:

- Filter strings reach Milvus as UTF-8, so a character outside the Basic
  Multilingual Plane parses, and an undeclared property's condition requires
  the stored type tag to be one the value compares with.
- Startup's already-exists guard goes, with its mocked-client test: Milvus
  answers a create of an existing collection with the same schema with
  success.
- The store no longer re-sorts search results, which Milvus returns best
  first.
- The mocked-client purge test disposes its registry engine when it fails.

The same changes as MemMachine#1736's 1a7fffa, d6fc219, 9fd7f76, 6fcd8c5, and
c264b3d, for this PR's store. MemMachine#1736's 28e8c50 and b3ef4f1 have no
counterpart here: startup prepares the store's one native collection before
any purge round runs, and the store refuses an unsupported metric at
construction, before anything is reserved.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

The declared path counted an int and a float as comparable either way, so
a float filter value on a declared int property reached Milvus as a float
literal against an INT64 field, which Milvus refuses to parse ("cannot
cast value to Int64", code 1100). A float now compares only with a float
property, and matches no int one, as a value of another type matches
nothing; an int still compares with a float property by value.

The new test filters a declared float property with an int and a declared
int property with a float; it fails with the float counted as comparable
with an int property.

The same change as MemMachine#1736's 31fc7c4, for this PR's store.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

…y name

MemMachine#1736's baabf48 creates Milvus native collections at Bounded by name,
and this PR's base carries that into startup's create, so the read level
the purge and the tombstone retention rely on no longer comes from
pymilvus's default. The consistency test now spies create_collection and
checks the level it names, as MemMachine#1736's test does; it fails with the level
dropped from the create. The design document and the store's docstring
say the store creates its one native collection at Bounded.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

MemMachine#1736's f56686f halves a Milvus upsert refused with RESOURCE_EXHAUSTED,
and this PR's base carries the halving into the partition handle's
`_upsert`. Its tests come here in partition terms: the integration test
upserts 1,200 records with a 60,000-character property, about 72 MB, and
fails with RESOURCE_EXHAUSTED without the halving; the mocked-client tests
pin the halving, a single refused entity raising, and a timeout or another
refusal sent once, on a handle `_partition_on` builds, which the mocked
delete test now uses too.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

…nt alone

MemMachine#1736's 49b9ec2 drops the offset field beside a declared Milvus
datetime, keeping its UTC instant alone, and this PR's base carries that
into the store. The tests follow in partition terms: the native
collection's fields are exactly the fixed ones and one per declared
property; a declared datetime is stored as its instant in UTC; and a store
whose declared datetime has the longest property key, 32 bytes, writes its
one field, reads it back, and matches the record by its instant, the test
MemMachine#1736's b015229 adds.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

The test of MemMachine#1813, merged into this PR's base, in partition terms: the
server defaults new collections to strict mode, the store's collection
reads back with it off, and a filter on a partition's unindexed property
is served.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

A partition stored every property of a record and filtered on any key,
which made a caller's arbitrary keys part of the store's schema: the
SQLite stores kept them in a JSON column and filtered with json_extract,
Milvus the keys its schema did not declare in a JSON field, and a filter
on a key the store never indexed scanned. Since EventMemory routes a
filter on an undeclared key to the segment store, the vector store need
not hold undeclared keys at all.

A partition now stores the properties its store declares and no others.
`upsert` raises UndeclaredPropertyKeyError before anything is sent for a
record naming an undeclared key, and PropertyTypeMismatchError for a
value of another type than its key declares; `query` raises
UndeclaredPropertyKeyError for a filter naming an undeclared key and
UnsupportedFilterError for a node outside the partition's
`supported_filter_nodes`. Both SQLite stores keep one typed, indexed,
nullable column per declared key on the records table (sql_columns.py);
sqlite-vec 0.1.9 rejects NULL in a vec0 metadata column and a declared
key is optional per record, so that store keeps the columns on the
records table and hands the KNN a `rowid IN (SELECT ...)` allowlist,
evaluating the filter during the search instead of after it. Qdrant
drops the JSON copy and keeps a payload field per declared key; Milvus
drops its JSON field and keeps its typed field per declared key.
Datetimes are stored as microseconds since the epoch where a backend has
no datetime type.

Since every key a filter may name is now indexed, the Qdrant store
creates its collection in strict mode (`unindexed_filtering_retrieve`
and `_update` false, Qdrant Cloud's default): a filter on an unindexed key is refused by the server instead
of scanned for. A leaf whose value is of another type than its key
declares matches nothing, as on the SQL stores; the Qdrant compiler
answers it with a filter no point satisfies, since the server would
refuse the condition for the field's index, and Milvus no longer
compares an int with a float key. Local mode does not record the
setting, so a unit test checks the request and integration tests the
server's answer.

`declared_schema_contract.py` states the contract every backend's test
module runs: which records a filtered search admits, over fixtures small
enough that every backend searches them exactly, checked after each
upsert so an approximate index fails on recall, by name, and not on the
filter.

On the registry-backed stores, the checks are the base handle's: `upsert`
runs require_declared_properties in place of the type check it ran, and
`query` runs require_supported_filter against the subclass's
`supported_filter_nodes`, which each subclass now implements. A datetime
column on the SQLite stores has a `tz_<key>` column beside it holding the
UTC offset in seconds, written with the value and read by no filter, so a
stored datetime is the value written, as on Milvus, Qdrant and the segment
store; the microseconds column alone would keep only the instant.

The Qdrant and Milvus design documents describe the declared-only
properties and Qdrant's strict mode.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

A declared datetime on the SQLite stores had a `tz_<key>` column beside its
microseconds column, holding the UTC offset in seconds that no filter
reads. The vector stores keep a datetime property's instant only, as
MemMachine#1736 now does for Milvus and MemMachine#1788 for Qdrant, and the segment store
keeps the offset, so the column, `offset_column_name`, and the value
written to it go: each declared property is one column, and a datetime
stays microseconds since the epoch.

The tests read a stored datetime back as its instant in UTC, and the
roundtrip test checks that the stored instant equals the written one.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn

Every embedder MemMachine ships produces vectors meant to be compared by
cosine -- OpenAI hard-coded it, Bedrock defaulted to it, SentenceTransformer
only reported what the model declared -- while every layer that touched a
score paid for the other three metrics in direction flags, threshold
directions, and per-backend tables mapping the enum onto native metric
names. `SimilarityMetric` is gone; scores are cosine similarities in
[-1, 1] and the names say so: `QueryMatch.score` and `SearchMatch.score`
become `cosine_similarity`, and `query(score_threshold=)` becomes
`query(min_cosine_similarity=)`, which no longer needs a direction to be
meaningful and is refused when not finite, as the threshold was. A store
and its partitions no longer have a `similarity_metric`, the schema a
partition is registered under no longer records one, and a search engine
factory takes the dimensions alone. The Bedrock embedder's
`similarity_metric` config key and semantic memory's
`vector_similarity_metric` go with it, and the install and configuration
docs drop them.

The vector graph stores carried a metric per stored embedding, as a
companion property beside every vector; that is gone and `Node.embeddings`
holds plain vectors. NebulaGraph's `cosine()` cannot take `APPROXIMATE` and
its vector indexes offer only L2 and IP. Cosine similarity between unit
vectors is their inner product, so embeddings are normalized on the way in
and compared with `inner_product()` against an IP index.

The cosine half of MemMachine#1598 (`abf92a3a4` on speedkick), re-derived on the
one-collection store: the rest of MemMachine#1598 (queries answer record UUIDs and
scores, no `get`, semantic memory's `vector_uuid`) and all of MemMachine#1603 are in
registry-backed base and its partition handle lose the metric, the stores'
own threshold checks become `require_valid_min_cosine_similarity`, and the
design documents describe cosine scoring and a schema without a metric.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01ESpWYTmCR7X3bJEpoA8SAn