Immutable transform wrapping for providers

[jlowin]

Providers can now be wrapped with transforms immutably via wrap_transform(), enabling the same provider instance to be used in multiple aggregators with different namespaces.

db = DatabaseProvider()

# Same provider, different namespaces - no mutation
server1.add_provider(db, namespace="db1")  
server2.add_provider(db, namespace="db2")

Key changes:

• Provider.wrap_transform(transform) returns a new _WrappedProvider that layers the transform on top without mutating the original
• AggregateProvider simplified to a plain .providers list, using wrap_transform(Namespace(...)) for namespacing
• FastMCP instances are auto-wrapped in FastMCPProvider when added to an aggregator (prevents accidentally bypassing middleware)
• FastMCP now inherits from AggregateProvider, removing duplicate aggregation logic

[chatgpt-codex-connector]

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Walkthrough

AggregateProvider is now exposed publicly and enhanced to support adding providers via add_provider(provider, *, namespace: str = ""), with internal storage renamed from _providers to providers and optional initial providers. Provider gained wrap_transform(transform) to produce an immutable wrapped provider implemented by a new internal _WrappedProvider class that delegates to an inner provider and composes transforms. FastMCP now inherits from AggregateProvider, uses add_provider for mounts/namespace handling, and delegates aggregation/list/get/task logic to the aggregate provider implementations.

Possibly related PRs

• PR 2653: Adds immutable provider-wrapping and namespace application semantics that overlap with wrap_transform and the _WrappedProvider implementation.
• PR 2663: Implements wrapped provider classes and modifies provider aggregation/export surface, directly touching _WrappedProvider and AggregateProvider exposure.
• PR 2635: Refactors server mounting to use provider abstractions and add_provider with namespace support, affecting FastMCP mounting and lifespan wiring.

🚥 Pre-merge checks | ✅ 1 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description is comprehensive and well-structured, covering key changes with code examples. However, the Contributors Checklist items are not checked off as required by the template.	Complete all checklist items in the Contributors Checklist section by checking the boxes to indicate compliance with repository requirements.
Docstring Coverage	⚠️ Warning	Docstring coverage is 79.55% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (1 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately and concisely summarizes the main change: introducing immutable transform wrapping for providers via the new wrap_transform() method.

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✨ Finishing touches

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