fix: move inbox attribute addition outside static pipeline cache

[holytshirt]

Summary

• Moves AddGlobalInboxAttributes / AddGlobalInboxAttributesAsync calls outside the static s_preAttributesMemento cache block in both BuildPipeline and BuildAsyncPipeline
• The cache now only stores the handler's declared pipeline attributes — inbox attributes are applied fresh each time based on the current _inboxConfiguration
• Previously, inbox attributes were cached alongside handler attributes, causing cross-contamination between pipeline builders with different inbox configurations:
  • Tests without inbox config would pick up cached inbox attributes from earlier tests → ArgumentOutOfRangeException when the handler factory couldn't create UseInboxHandlerAsync<T>
  • Tests with inbox config hitting a cache populated without inbox → inbox handler never added → inbox assertions failed
  • On cache miss with inbox config, the async version had a duplicate call that added the inbox handler twice

Test plan

• CI core tests pass (557 total, 547 passed, 0 failed)
• AsyncCommandProcessorPublishObservabilityTests — previously failing, now pass
• CommandProcessorBuildDefaultInboxPublishAsyncTests — previously failing, now passes
• No regressions in other pipeline builder tests

🤖 Generated with Claude Code

[codescene-delta-analysis]

Gates Passed
4 Quality Gates Passed

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Quality Gate Profile: Clean Code Collective
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[claude]

Code Review

The PR has evolved well from the initial version. Here is a fresh assessment of the current state.

What is now correct

Cache isolation fix - AddGlobalInboxAttributes(Async) is applied after the cache block, so s_preAttributesMemento stores only the handler declared attributes. Per-instance inbox configuration is applied dynamically on every call.

Async duplicate-call removed - The original BuildAsyncPipeline added the inbox attribute twice on cache miss. Now both sync and async paths are symmetric.

PushOntoAttributeList no longer mutates cached objects - Replacing handler.Step++ with minStep - 1 is a significant correctness improvement. The old code incremented Step on RequestHandlerAttribute instances held inside the static cache, so step values grew unboundedly across the lifetime of a service. The new approach computes the inbox step relative to the original unmodified cached values on each call.

Both reversal directions tested - All four test scenarios are now present: with-inbox to without-inbox, without-inbox to with-inbox, and both async equivalents. This was the main gap in earlier iterations.

Redundant null check removed - The dead null guard after the early return is gone from both AddGlobalInboxAttributes and AddGlobalInboxAttributesAsync.

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Remaining observations

FindHandlerMethod() called twice per add - In AddGlobalInboxAttributes(Async), FindHandlerMethod() is called once for HasNoInboxAttributesInPipeline() and once for HasExistingUseInboxAttributesInPipeline(). Since this now runs on every pipeline build (not just cache misses), the double reflection hit is more frequent than before. Caching the MethodInfo in a local variable would halve the reflection cost. Low priority follow-up.

s_postAttributesMemento is never populated (pre-existing) - In both BuildPipeline and BuildAsyncPipeline, when post-attributes are not in the cache they are computed but never added via TryAdd. Post-attributes are therefore re-reflected on every call. This predates the PR but worth a follow-up issue.

Step underflow is benign but undocumented - When existing attributes include step 0, minStep - 1 equals -1. Ordering remains correct (inbox sorts last in descending order, meaning outermost in the pipeline). The existing comment explains the invariant but noting that steps can be negative would help maintainers not be surprised by diagnostic output.

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Summary

Area	Status
Cache contamination fix	Correct
Async duplicate-call fix	Correct
Mutation of cached attributes	Fixed
Both cache-reversal directions tested	Now covered
Redundant null check	Removed
Double FindHandlerMethod() reflection per call	Minor follow-up
s_postAttributesMemento never populated	Pre-existing follow-up

The fix is correct and complete. Ready to merge.

[iancooper]

TBH I never really liked the global inbox attribute but we came under such pressure from the CTO at Huddle to add it. The problem it creates is why not global outbox, resilience pipeline etc, which gets into fluent over attribute syntax questions

[holytshirt]

@iancooper are we okay with the order being negative, I assume it's not a problem, from reviewing the other code I think it's fine.

[iancooper]

I guess