1. lib/snippets.ts + lib/memory-actions.ts (×2): shared-project key
lookups were querying `projects` by key with no visibility scope. Since
`projects.key` is unique per user (not global), the unscoped match
could resolve another user's project entirely. Restricted the lookups
to `readableProjectIds(userId, groupNames)` — own + shared only.
2. lib/access.ts getAccessibleProjects: a stray `if (existing) continue`
inside the share-collapse loop short-circuited on the first match,
killing the rw-beats-ro upgrade path. Two-group cases where one share
was ro and another rw on the same project were incorrectly resolved
as ro. Replaced with explicit owner/rw skip.
3. lib/mcp/tools.ts snippetPut: removed a dead `void exists` block that
looked like an authorization pre-flight but was actually a no-op —
real write authorization lives inside putSnippet, called next. Added
a comment at the call site documenting where the check is.
4. memory.delete + snippet.delete: previously had no optimistic-lock
CAS, so a concurrent peer edit could be silently overwritten by a
delete on a stale view. Added optional `version` to MemoryDeleteInput
(new) and SnippetDeleteInput (extended); UPDATE WHERE now CASes on
version; 0-row response surfaces CONCURRENT_EDIT_ERROR. Web detail
pages pass `version` through hidden form inputs. When the caller
doesn't supply a version, falls back to the version we just read in
the same handler for in-handler consistency.
5. lib/mcp/tools.ts memorySearch re-fetch: missing `isNull(deletedAt)`
on the post-search row hydration left a TOCTOU window where a row
soft-deleted between the search and the re-fetch would be returned.
Visibility is still enforced by searchMemories itself.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>