v7.56.0

Pairs with engine-service-v0.1.129, unchanged from 7.55.3 — this release carries no engine-side change.

Added

• alias_of on the MCP catalog update tool. The engine has supported it
  on /update all along — it is in UPDATABLE_DOC_COLUMNS, and resolve
  walks the alias chain server-side — but the MCP surface did not offer it, so
  the capability was reachable from Python (HttpCatalogClient.set_alias) and
  from nowhere an operator or an agent actually works. Aliasing is the answer
  when one document acquires a second catalog entry: it keeps search results
  clean without deleting the older entry and the links pointing at it.

Fixed

• nx dt index no longer registers a duplicate catalog document for a file
  already catalogued under another owner. The indexer resolved its owner from
  corpus and then looked the document up with an owner-scoped
  by_file_path, which structurally cannot see a row living under a different
  owner. It now resolves through by_source_uri, which is deliberately not
  owner-scoped, so a DEVONthink URI finds its document wherever it lives.
  Measured: one remediation run produced 19 duplicate pairs, each duplicate
  carrying the weaker file:// identity rather than the
  x-devonthink-item:// one that survives DEVONthink moving the file.
• The DEVONthink URI stamp no longer writes to the wrong document. It
  resolved the row to stamp by file path alone, on the premise that the
  catalog holds one row per indexed file. The schema does not enforce that —
  the only uniqueness is a partial index on (tenant_id, source_uri) — so with
  two rows for one path it could stamp the one that already held the URI and
  silently no-op, leaving the row that needed the identity on file://. It now
  resolves by URI first and falls back to file path.
• A --collection that disagrees with an existing document is now a loud
  error (SourceUriCollectionMismatchError) rather than a silent duplicate.
  Naming a source URI and a collection that disagree is a move, not a
  re-index.
• A source-URI failure fails one record, not the whole batch. Passing
  source_uri made SourceUriNotFoundError and
  SourceUriCollectionMismatchError reachable from a batch for the first time;
  neither was in PER_RECORD_SURVIVABLE_EXCEPTIONS, so either aborted every
  record after it. Single-file commands are unaffected — they already convert
  both to a ClickException at the wrapper boundary.
• A path naming several documents is reported rather than silently
  resolved. find_by_file_path's contract was already "first match"; what it
  never did was say when it had chosen. It now warns with the count, the chosen
  tumbler and the others. nx catalog links-for-file uses a new plural lookup:
  the command answers about a FILE, and showing one document's links as the
  file's hid the rest with no way for the reader to know they existed.
• The taxonomy cross-space rebuild refusal now covers the whole function and
  is reachable. 7.55.3 shipped it above only some of the paths that fetch
  centroids, so a collection that had migrated embedders could still reach a
  rebuild through an early return. The refusal also names a remedy that now
  runs: nx taxonomy reset discards a collection's topics, assignments, links
  and centroids without touching its documents or chunks, prompting first and
  reporting how many topics were operator-accepted.
• Local PG provisioning refuses to run as root before the bundle download,
  not after it, and the guard now sits on the subprocess choke point rather
  than beside it.
• MCP reports its SDK patch status where a handler can receive it.

Internal

• One substrate-heavy test suite per box, enforced by a lease rather than by
  convention: two concurrent runs exhaust the machine-wide SysV shared-memory
  budget and report the contention as thousands of setup errors that read as
  breakage. A nested pytest run is recognised as a descendant of the holder
  rather than as a rival.
• Lease-refusal assertions key on the refusing gate's own prefixed line, since
  two gates share exit 75 and both print "refusing to start".