chore: EntityId Migration + Finalized Test Migration

[Eli Pinkerton (wallstop)]

Description

This PR updates DxMessaging for Unity's EntityId migration and completes the no-yield PlayMode test migration.

What changed:

• Switched Unity object identity reads to a single version-gated source, InstanceId.StableId, to keep compatibility with Unity 6.4+ deprecations and Unity 6.5+ compile behavior while preserving the same 32-bit dispatch key.
• Updated runtime/editor call sites that previously read GetInstanceID() directly to use the shared stable-id source.
• Added InstanceIdSourceTests to lock migration behavior and guard against new direct GetInstanceID() usage outside the gated source.
• Converted remaining no-yield PlayMode [UnityTest] methods to plain [Test] and tightened the contract test so the migration allowlist is now empty.
• Updated user docs (README, compatibility, comparisons, and test-performance runbook) and internal AI testing guidance to reflect the completed migration and current benchmark framing.

User-facing impact:

• No public API changes.
• Package remains compatible across supported Unity versions, including Unity 6.5+ where GetInstanceID() is removed.
• PlayMode test maintenance and runtime test performance improve by removing unnecessary coroutine wrappers.

Related Issue

Fixes #208

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Refactor (code change that neither fixes a bug nor adds a feature)

Checklist

• All tests pass locally
• Code is properly formatted
• I have added tests that prove my fix is effective or my feature works
• I have updated the documentation accordingly
• I have updated the CHANGELOG
• My changes do not introduce breaking changes, or breaking changes are documented

---

Note

Medium Risk
Changes how Unity object IDs are sourced for dispatch and editor tooling on the Unity 6 migration path; behavior is heavily tested and the 32-bit key is intended to be unchanged, but any mistake would affect targeting and equality.

Overview
Routes all Unity object identity reads for the dispatch key through a new version-gated InstanceId.StableId: Unity 6.4+ uses EntityId.ToULong(...) (low 32 bits), older editors keep GetInstanceID(), with no public API change and the same 32-bit key semantics. Runtime/editor call sites that called GetInstanceID() directly now use StableId, and InstanceIdSourceTests locks parity plus a source-scan drift guard so GetInstanceID() cannot reappear outside the gated helper.

Finishes the PlayMode test cleanup by converting the remaining synchronous [UnityTest] methods to [Test] and clearing the pendingMigration allowlist in TestAttributeContractTests, so the no-yield rule applies tree-wide.

Docs and changelog are updated for Unity 6.5+ compatibility (#208), completed fast-test migration guidance, and Standalone IL2CPP-focused benchmark framing (README/comparisons/runbooks).

^{Reviewed by Cursor Bugbot for commit c357c2b. Bugbot is set up for automated code reviews on this repo. Configure here.}

[Copilot]

Pull request overview

This PR updates DxMessaging to remain compatible with Unity’s ongoing Unity 6 object-identity (EntityId) migration by routing dispatch-key identity through a single version-gated source (InstanceId.StableId), and finishes the PlayMode “no-yield [UnityTest]” migration by converting remaining synchronous coroutine-shaped tests to plain [Test]. It also updates documentation, changelog entries, and internal AI/testing guidance to reflect the completed migrations and current benchmarking framing.

Changes:

• Introduces InstanceId.StableId(UnityEngine.Object) (Unity 6.4+ uses EntityId.ToULong(GetEntityId()) low 32 bits; older Unity uses GetInstanceID()), and updates runtime/editor call sites to use it.
• Converts remaining synchronous PlayMode [UnityTest] IEnumerator ... yield break; tests to [Test] void ..., and makes the “pending migration” allowlist empty to enforce the rule repo-wide.
• Adds InstanceIdSourceTests to lock parity with legacy IDs (where available) and to source-scan against direct GetInstanceID() usage outside the gated helper; updates docs/runbooks/changelog accordingly.

Reviewed changes

Copilot reviewed 22 out of 23 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
Tests/Runtime/Unity/MessagingComponentProviderIntegrationTests.cs	Converts remaining no-yield [UnityTest] methods to [Test].
Tests/Runtime/Core/TestAttributeContractTests.cs	Empties the pendingMigration allowlist and updates migration-complete commentary for the no-yield [UnityTest] guard.
Tests/Runtime/Core/OrderingAcrossEnableCyclesTests.cs	Converts no-yield [UnityTest] methods to [Test].
Tests/Runtime/Core/NominalTests.cs	Converts multiple no-yield [UnityTest] methods to [Test] and removes coroutine-only endings.
Tests/Runtime/Core/LifecycleEdgeCasesTests.cs	Converts no-yield [UnityTest] methods to [Test] while preserving scenario parameterization.
Tests/Runtime/Core/EnablementTests.cs	Converts a no-yield [UnityTest] method to [Test].
Tests/Runtime/Core/EdgeCaseTests.cs	Converts multiple no-yield [UnityTest] methods to [Test].
Tests/Runtime/Core/DefaultBusFallbackTests.cs	Converts remaining no-yield [UnityTest] methods to [Test].
Tests/Runtime/Core/BaseCallContractTests.cs	Converts remaining no-yield [UnityTest] methods to [Test].
Tests/Runtime/Core/InstanceIdSourceTests.cs	Adds tests validating StableId parity (where possible) and a drift-guard source scan to prevent reintroducing direct GetInstanceID() reads.
Tests/Runtime/Core/InstanceIdSourceTests.cs.meta	Adds Unity meta for the new test script.
Runtime/Core/MessageBus/MessageRegistrationBuilder.cs	Replaces direct GetInstanceID() usage with InstanceId.StableId(...) when resolving Unity owners.
Runtime/Core/InstanceId.cs	Implements StableId(...) and routes Unity-object InstanceId construction through it.
Editor/Testing/MessagingComponentEditorHarness.cs	Uses StableId for deterministic ordering of listener diagnostics views without calling GetInstanceID() directly.
Editor/CustomEditors/MessageAwareComponentInspectorOverlay.cs	Uses StableId for repaint-latch identity on Unity 6 migration path.
README.md	Updates performance badge text and benchmark framing/numbers to Standalone IL2CPP focus.
docs/runbooks/test-suite-performance.md	Updates runbook to reflect completion of the no-yield test migration and empty allowlist.
docs/reference/compatibility.md	Documents Unity 6 EntityId migration handling and Unity 6.5+ GetInstanceID() removal compatibility.
docs/architecture/comparisons.md	Reframes comparisons around Standalone IL2CPP live tables and updates historical snapshot guidance/numbers.
CHANGELOG.md	Adds changelog entry describing the EntityId/StableId migration and compatibility outcome for Unity 6.5+.
.llm/skills/testing/fast-unity-tests.md	Updates internal testing skill doc to mark no-yield migration as complete.
.llm/skills/index.md	Updates skill index metadata (line count).
.llm/context.md	Updates AI agent guidance to reflect empty allowlist and completed migration status.

Files not reviewed (1)

• Tests/Runtime/Core/InstanceIdSourceTests.cs.meta: Generated file

[github-actions]

Dispatch throughput (Unity 6000.3.16f1)

Runner: 13th Gen Intel(R) Core(TM) i9-13900KF, 24C/32T @ 3000MHz; 64GB DDR5@4200; NVIDIA GeForce RTX 3060; Microsoft Windows 11 Pro N (10.0.26200)

Regenerated by CI from commit c357c2b (run logs). These numbers MOVED versus the committed doc; CI commits the refreshed doc directly to the default branch after this PR merges.

Latest CI benchmark run: Unity 6000.3.16f1, commit c357c2b7237b97f67c82f8a9465b7d96322a1c6e.

Runner: 13th Gen Intel(R) Core(TM) i9-13900KF, 24C/32T @ 3000MHz; 64GB DDR5@4200; NVIDIA GeForce RTX 3060; Microsoft Windows 11 Pro N (10.0.26200)

Dispatch throughput - Standalone (IL2CPP)

Platform: Standalone IL2CPP x64 Release (WindowsPlayer; Unity 6000.3.16f1).

Scenario	Throughput / Wall clock	Allocated bytes
Untargeted Flood (One Handler)	38.27 M emits/sec	0 B
Untargeted Flood (Four Handlers, One Priority)	24.29 M emits/sec	0 B
Untargeted Flood (Four Handlers, Four Priorities)	24.33 M emits/sec	0 B
Untargeted First Dispatch (Cold, Distinct Types)	0.203 ms	0 B
Targeted Flood (One Listener)	9.68 M emits/sec	0 B
Targeted Flood (Sixteen Listeners)	6.74 M emits/sec	0 B
Targeted First Dispatch (Cold, Distinct Types)	0.200 ms	0 B
Broadcast Flood (One Handler)	19.20 M emits/sec	0 B
Broadcast First Dispatch (Cold, Distinct Types)	0.207 ms	0 B
Interceptor Heavy (Four Interceptors)	3.07 M emits/sec	0 B
Post-Processing Heavy (Four Post-Processors)	11.78 M emits/sec	0 B
Registration Flood (1000 Types, Cold Bus)	529.570 ms	0 B
Registration Flood (1000 Types, Warm JIT)	15.807 ms	0 B
Deregistration Flood (1000 Types, Cold)	1.133 ms	0 B
Deregistration Flood (1000 Types, Warm JIT)	1.125 ms	0 B

Library comparison - throughput (Standalone (IL2CPP))

Technology	Global -> 1 subscriber	Global -> 16 subscribers	Keyed/targeted -> 1 of many	Priority-ordered dispatch	Filtered/intercepted dispatch	Post-processing dispatch	Subscribe/unsubscribe churn	Struct message (zero-copy)
DxMessaging	28.71 M emits/sec	9.93 M emits/sec	9.71 M emits/sec	21.24 M emits/sec	6.75 M emits/sec	12.53 M emits/sec	0.50 M emits/sec	27.76 M emits/sec
MessagePipe	84.99 M emits/sec	15.63 M emits/sec	9.86 M emits/sec	N/A	60.24 M emits/sec	N/A	2.06 M emits/sec	76.64 M emits/sec
UniRx MessageBroker	5.24 M emits/sec	2.73 M emits/sec	N/A	N/A	N/A	N/A	0.78 M emits/sec	4.35 M emits/sec
Zenject SignalBus	2.29 M emits/sec	1.15 M emits/sec	N/A	N/A	N/A	N/A	1.60 M emits/sec	2.08 M emits/sec
Unity Atoms	96.53 M emits/sec	33.70 M emits/sec	102.54 M emits/sec	N/A	N/A	N/A	10.87 M emits/sec	N/A
ScriptableObject channel	140.81 M emits/sec	21.39 M emits/sec	188.60 M emits/sec	N/A	N/A	N/A	28.79 M emits/sec	145.36 M emits/sec
UnityEvent	78.69 M emits/sec	10.13 M emits/sec	76.82 M emits/sec	N/A	N/A	N/A	3.46 M emits/sec	89.40 M emits/sec
C# event	375.45 M emits/sec	45.25 M emits/sec	68.99 M emits/sec	N/A	N/A	N/A	10.73 M emits/sec	297.04 M emits/sec
Unity SendMessage	8.91 M emits/sec	0.94 M emits/sec	8.43 M emits/sec	N/A	N/A	N/A	N/A	N/A

Library comparison - allocations, bytes per op (Standalone (IL2CPP))

Technology	Global -> 1 subscriber	Global -> 16 subscribers	Keyed/targeted -> 1 of many	Priority-ordered dispatch	Filtered/intercepted dispatch	Post-processing dispatch	Subscribe/unsubscribe churn	Struct message (zero-copy)
DxMessaging	0	0	0	0	0	0	0	0
MessagePipe	0	0	0	N/A	0	N/A	0	0
UniRx MessageBroker	0	0	N/A	N/A	N/A	N/A	0	0
Zenject SignalBus	0	0	N/A	N/A	N/A	N/A	0	0
Unity Atoms	0	0	0	N/A	N/A	N/A	0	N/A
ScriptableObject channel	0	0	0	N/A	N/A	N/A	0	0
UnityEvent	0	0	0	N/A	N/A	N/A	0	0
C# event	0	0	0	N/A	N/A	N/A	0	0
Unity SendMessage	0	0	0	N/A	N/A	N/A	N/A	N/A

[github-actions]

DxMessaging perf deltas vs master baseline (Unity 6000.3.16f1, Standalone IL2CPP)

Regenerated by CI (run logs). Changed beyond tolerance: yes. Regression gate: passed.

Scenario	Baseline	Current	Delta
Untargeted Flood (One Handler)	37.92 M emits/sec, 0 B	38.27 M emits/sec, 0 B	+0.92%
Untargeted Flood (Four Handlers, One Priority)	23.43 M emits/sec, 0 B	24.29 M emits/sec, 0 B	+3.68%
Untargeted Flood (Four Handlers, Four Priorities)	25.31 M emits/sec, 0 B	24.33 M emits/sec, 0 B	-3.86%
Untargeted First Dispatch (Cold, Distinct Types)	0.195 ms, 0 B	0.203 ms, 0 B	+4.10%
Targeted Flood (One Listener)	9.94 M emits/sec, 0 B	9.68 M emits/sec, 0 B	-2.63%
Targeted Flood (Sixteen Listeners)	5.96 M emits/sec, 0 B	6.74 M emits/sec, 0 B	+13.11%
Targeted First Dispatch (Cold, Distinct Types)	0.193 ms, 0 B	0.200 ms, 0 B	+3.63%
Broadcast Flood (One Handler)	18.85 M emits/sec, 0 B	19.20 M emits/sec, 0 B	+1.84%
Broadcast First Dispatch (Cold, Distinct Types)	0.206 ms, 0 B	0.207 ms, 0 B	+0.49%
Interceptor Heavy (Four Interceptors)	3.04 M emits/sec, 0 B	3.07 M emits/sec, 0 B	+0.79%
Post-Processing Heavy (Four Post-Processors)	11.08 M emits/sec, 0 B	11.78 M emits/sec, 0 B	+6.38%
Registration Flood (1000 Types, Cold Bus)	594.028 ms, 0 B	529.570 ms, 0 B	-10.85%
Registration Flood (1000 Types, Warm JIT)	10.841 ms, 0 B	15.807 ms, 0 B	+45.81%
Deregistration Flood (1000 Types, Cold)	1.030 ms, 0 B	1.133 ms, 0 B	+10.00%
Deregistration Flood (1000 Types, Warm JIT)	1.245 ms, 0 B	1.125 ms, 0 B	-9.64%
Global -> 1 subscriber	27.84 M emits/sec, 0 B	28.71 M emits/sec, 0 B	+3.10%
Global -> 16 subscribers	10.49 M emits/sec, 0 B	9.93 M emits/sec, 0 B	-5.31%
Keyed/targeted -> 1 of many	10.63 M emits/sec, 0 B	9.71 M emits/sec, 0 B	-8.64%
Priority-ordered dispatch	24.38 M emits/sec, 0 B	21.24 M emits/sec, 0 B	-12.87%
Filtered/intercepted dispatch	7.54 M emits/sec, 0 B	6.75 M emits/sec, 0 B	-10.44%
Post-processing dispatch	12.61 M emits/sec, 0 B	12.53 M emits/sec, 0 B	-0.68%
Subscribe/unsubscribe churn	0.48 M emits/sec, 0 B	0.50 M emits/sec, 0 B	+4.31%
Struct message (zero-copy)	28.55 M emits/sec, 0 B	27.76 M emits/sec, 0 B	-2.75%