Guard tenant context at database access, not at object creation

.rubocop.yml

@@ -392,6 +392,9 @@ Security/JSONLoad:
 
 Security/MarshalLoad:
   Enabled: true
+  Exclude:
+    # Round-tripping records through Marshal is what this file tests.
+    - 'test/unit/serialization_test.rb'
 
 Security/Open:
   Enabled: true

CHANGELOG.md

@@ -2,10 +2,30 @@
 
 ## next / unreleased
 
+### Breaking change: serialized payloads carry the tenant
+
+A tenanted record now writes its tenant into the payload produced by `Marshal`, JSON, YAML, and MessagePack, so that it keeps its tenant identity when it is loaded in another tenant context or in none. This fixes a hang in parallel test suites, where a worker died reporting an exception that carried a record with a loaded association. See [#243](https://github.com/basecamp/activerecord-tenanted/issues/243). @flavorjones
+
+The payload format changes, and the change is not backward compatible. An earlier version of this gem reading a payload written by this version raises `ActiveModel::UnknownAttributeError` for JSON, and gains a phantom `tenant` attribute for `Marshal` and MessagePack. Payloads written by an earlier version are still read correctly by this version, and keep the loading context as they did before.
+
+Discard persisted payloads before upgrading, including cache entries, enqueued jobs, and serialized columns. Expect the same incompatibility during a rolling deploy, while old and new code run at the same time.
+
+### Breaking change: record equality
+
+`==`, `eql?`, and `#hash` now take the tenant into account. Two records of the same class with the same id in different tenant databases were previously equal, and collided as `Hash` keys and in a `Set`. They are now distinct. Code that compares records across tenants, or that relies on `has_many` assignment treating them as interchangeable, will behave differently. @flavorjones
+
 ### Fixed
 
 - `Tenanted::GlobalId::Locator` now inherits from `GlobalID::Locator::UnscopedLocator`, which is the locator Rails uses by default. Two behavior changes follow: GlobalID lookups no longer apply a model's `default_scope`, matching Rails; and `#locate_many` is now implemented, which Active Job on Rails edge requires to deserialize GlobalID arguments. `#locate_many` enforces the same tenant safety checks as `#locate`. @flavorjones
 - `Tenanted::GlobalId::Locator` no longer emits a deprecation warning from GlobalID 1.4.0 about the missing `model_class` method. @flavorjones
+- The tenant context check now runs when an association reads or writes the database, rather than when the `Association` object is created. A polymorphic association is checked against the class it points at, instead of being presumed tenanted. @flavorjones
+- `#reload`, `#destroy`, `#delete`, `#update_column`, `#update_columns`, `#touch`, `#increment!`, `#decrement!`, and `#valid?` check the tenant context before they touch the database. They previously operated on the current tenant's database whatever the record's tenant. @flavorjones
+- Assigning a `belongs_to` target that belongs to another tenant now raises `WrongTenantError` when the record is saved, rather than writing a foreign key that points into another tenant's database. @flavorjones
+- `UntenantedConnectionPool` implements `#clear_query_cache` as a no-op, having no query cache to clear. `ActiveRecord::Persistence#reload` calls it before it asks for a connection, so an untenanted `#reload` previously raised `NoMethodError` instead of `NoTenantError`. @flavorjones
+
+### Developer infrastructure
+
+- Added `msgpack` as a development dependency, so that the serialization tests can exercise a MessagePack round trip. @flavorjones
 
 
 ## v0.7.0 / 2026-06-08

Gemfile

@@ -12,6 +12,7 @@ group :development, :test do
   gem "minitest", "6.0.6"
   gem "minitest-mock", "5.27.0"
   gem "minitest-parallel_fork", "2.1.1", require: false
+  gem "msgpack", "1.8.3"
   gem "sqlite3", "2.9.4"
 end
 

Gemfile.lock

@@ -187,6 +187,7 @@ GEM
     minitest-mock (5.27.0)
     minitest-parallel_fork (2.1.1)
       minitest (>= 5.15.0)
+    msgpack (1.8.3)
     net-imap (0.6.6)
       date
       net-protocol
@@ -197,6 +198,14 @@ GEM
     net-smtp (0.5.1)
       net-protocol
     nio4r (2.7.5)
+    nokogiri (1.19.4-aarch64-linux-gnu)
+      racc (~> 1.4)
+    nokogiri (1.19.4-aarch64-linux-musl)
+      racc (~> 1.4)
+    nokogiri (1.19.4-arm-linux-gnu)
+      racc (~> 1.4)
+    nokogiri (1.19.4-arm-linux-musl)
+      racc (~> 1.4)
     nokogiri (1.19.4-arm64-darwin)
       racc (~> 1.4)
     nokogiri (1.19.4-x86_64-darwin)
@@ -315,6 +324,10 @@ GEM
       fugit (~> 1.11)
       railties (>= 7.1)
       thor (>= 1.3.1)
+    sqlite3 (2.9.4-aarch64-linux-gnu)
+    sqlite3 (2.9.4-aarch64-linux-musl)
+    sqlite3 (2.9.4-arm-linux-gnu)
+    sqlite3 (2.9.4-arm-linux-musl)
     sqlite3 (2.9.4-arm64-darwin)
     sqlite3 (2.9.4-x86_64-darwin)
     sqlite3 (2.9.4-x86_64-linux-gnu)
@@ -325,6 +338,9 @@ GEM
     tailwindcss-rails (4.6.0)
       railties (>= 7.0.0)
       tailwindcss-ruby (~> 4.0)
+    tailwindcss-ruby (4.3.3)
+    tailwindcss-ruby (4.3.3-aarch64-linux-gnu)
+    tailwindcss-ruby (4.3.3-aarch64-linux-musl)
     tailwindcss-ruby (4.3.3-arm64-darwin)
     tailwindcss-ruby (4.3.3-x86_64-darwin)
     tailwindcss-ruby (4.3.3-x86_64-linux-gnu)
@@ -352,9 +368,12 @@ GEM
     zeitwerk (2.8.3)
 
 PLATFORMS
+  aarch64-linux-gnu
+  aarch64-linux-musl
+  arm-linux-gnu
+  arm-linux-musl
   arm64-darwin
   x86_64-darwin
-  x86_64-linux
   x86_64-linux-gnu
   x86_64-linux-musl
 
@@ -368,6 +387,7 @@ DEPENDENCIES
   minitest (= 6.0.6)
   minitest-mock (= 5.27.0)
   minitest-parallel_fork (= 2.1.1)
+  msgpack (= 1.8.3)
   propshaft
   puma (>= 5.0)
   rails!
@@ -385,5 +405,143 @@ DEPENDENCIES
   tailwindcss-rails
   turbo-rails
 
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+  tailwindcss-ruby (4.3.3-aarch64-linux-musl) sha256=72b77ca9edea82383dd09510ab520a122e3cb9f9864ca5b38e27698098d2b899
+  tailwindcss-ruby (4.3.3-arm64-darwin) sha256=776c51fc734aac64bde0c253eadd2ed2e610b2ba0d8e760501fe7cbec55fd6cf
+  tailwindcss-ruby (4.3.3-x86_64-darwin) sha256=483011e5d3792cf5ef4afdfb04c1d95daccf42c30cdb6fe53b77520954e7b922
+  tailwindcss-ruby (4.3.3-x86_64-linux-gnu) sha256=2337017ff8b02698480eae1e9637cf01faa0e4824db89d067a13c5a5ee38c9b2
+  tailwindcss-ruby (4.3.3-x86_64-linux-musl) sha256=27d478c417bcf73828e5b544744c5bdfd5b5cb54f1a266fc4f185281c32efe6c
+  thor (1.5.0) sha256=e3a9e55fe857e44859ce104a84675ab6e8cd59c650a49106a05f55f136425e73
+  timeout (0.6.1) sha256=78f57368a7e7bbadec56971f78a3f5ecbcfb59b7fcbb0a3ed6ddc08a5094accb
+  tsort (0.2.0) sha256=9650a793f6859a43b6641671278f79cfead60ac714148aabe4e3f0060480089f
+  turbo-rails (2.0.23) sha256=ee0d90733aafff056cf51ff11e803d65e43cae258cc55f6492020ec1f9f9315f
+  tzinfo (2.0.6) sha256=8daf828cc77bcf7d63b0e3bdb6caa47e2272dcfaf4fbfe46f8c3a9df087a829b
+  unicode-display_width (3.2.0) sha256=0cdd96b5681a5949cdbc2c55e7b420facae74c4aaf9a9815eee1087cb1853c42
+  unicode-emoji (4.2.0) sha256=519e69150f75652e40bf736106cfbc8f0f73aa3fb6a65afe62fefa7f80b0f80f
+  uri (1.1.1) sha256=379fa58d27ffb1387eaada68c749d1426738bd0f654d812fcc07e7568f5c57c6
+  useragent (0.16.11) sha256=700e6413ad4bb954bb63547fa098dddf7b0ebe75b40cc6f93b8d54255b173844
+  websocket (1.2.11) sha256=b7e7a74e2410b5e85c25858b26b3322f29161e300935f70a0e0d3c35e0462737
+  websocket-driver (0.8.2) sha256=97c556b019bf3410b4961002ac501621e9322d3f8a7bc02161a09301cc4c4146
+  websocket-extensions (0.1.5) sha256=1c6ba63092cda343eb53fc657110c71c754c56484aad42578495227d717a8241
+  xpath (3.2.0) sha256=6dfda79d91bb3b949b947ecc5919f042ef2f399b904013eb3ef6d20dd3a4082e
+  zeitwerk (2.8.3) sha256=2c85125a8467ce069e20123d1e709a08955c9d29c118c25b46b7b7fafdbb92e5
+
 BUNDLED WITH
-   2.7.2
+  4.0.13

gemfiles/rails_8_1.gemfile

@@ -22,6 +22,7 @@ group :development, :test do
   gem "minitest", "6.0.6"
   gem "minitest-mock", "5.27.0"
   gem "minitest-parallel_fork", "2.1.1", require: false
+  gem "msgpack", "1.8.3"
   gem "sqlite3", "2.9.4"
 end
 

gemfiles/rails_edge.gemfile

@@ -22,6 +22,7 @@ group :development, :test do
   gem "minitest", "6.0.6"
   gem "minitest-mock", "5.27.0"
   gem "minitest-parallel_fork", "2.1.1", require: false
+  gem "msgpack", "1.8.3"
   gem "sqlite3", "2.9.4"
 end
 

lib/active_record/tenanted/associations.rb

@@ -0,0 +1,32 @@
+# frozen_string_literal: true
+
+module ActiveRecord
+  module Tenanted
+    # Tenant context is checked when an association reads or writes the database, and not when the
+    # Association object is created. Serializers create associations to dump and restore their
+    # targets without ever going near a connection, and must not be tripped up by the check.
+    #
+    # `klass` is resolved at both of these seams, so a polymorphic association is checked against
+    # the class it actually points at rather than being presumed tenanted.
+    module Associations # :nodoc:
+      # Every query built on behalf of an association funnels through here, including the ones
+      # issued by a collection proxy that has outlived the tenant context it was created in.
+      def scope
+        ensure_owner_tenant_context_safety
+        super
+      end
+
+      private
+        # Called by the collection and singular association readers, so that the exception is
+        # raised at the call site that made the mistake and not at the eventual query.
+        def ensure_klass_exists!
+          super
+          ensure_owner_tenant_context_safety
+        end
+
+        def ensure_owner_tenant_context_safety
+          owner.ensure_tenant_context_safety if owner.class.tenanted? && klass&.tenanted?
+        end
+    end
+  end
+end