Supply the bound domain to provider initialization across SDKs

[jonathannorris]

Context

The spec now supplies the bound domain to a provider's initialize function, and adds an opt-in domain-scoped provider declaration that the API enforces by binding such a provider to at most one domain. This lets stateful providers (e.g. an OFREP static-context provider with a persistent cache) scope their state to a single, unambiguous domain.

• Spec PR: feat: supply the bound domain to provider initialization #393
• Related protocol ADR: docs: amend ADR 0009 to tie cache key to OFREP resource (domain, url, auth) protocol#80 (OFREP cache key motivating this)

Relevant spec sections

• Section 1.1 - Flag evaluation API
• Section 2.4 - Initialization

Requirements summary

Requirement	Level	Description
1.1.2.2	MUST	The provider mutator supplies the bound domain (if any) when invoking initialize
2.4.1	MAY	initialize accepts the global evaluation context and an optional bound domain
2.4.3	MAY	A provider may declare itself domain-scoped (maintains per-domain state that can't be shared)
2.4.4	MUST	A domain-scoped provider must accept the bound domain during initialization
1.1.8 / 1.1.8.1	MUST NOT	The provider mutator must not bind a domain-scoped provider instance to more than one domain, rejecting any attempt to bind an already-bound instance to an additional domain

Section 1.8.4 prose was also updated: a provider instance can back multiple domains unless it declares itself domain-scoped.

Non-functional requirements

• Add the domain parameter in a backwards-compatible way where the language allows it (optional/overloaded/default parameter). This is non-breaking in JS, Java, Python, .NET, Ruby, and Rust.
• In languages where initialize/Init is a required interface/protocol method (Go, Kotlin, Swift), introduce it via an optional secondary interface or batch it into the next major; the domain-scoped declaration should likewise be opt-in.
• PHP has no initialization hook today; adding one is out of scope here unless done separately.
• Associated testing and README/docs updates.

Implementation tracking

Child issues:

• JS: Supply the bound domain to provider initialization js-sdk#1434
• Java: Supply the bound domain to provider initialization java-sdk#1981
• Go: Supply the bound domain to provider initialization go-sdk#518
• Python: Supply the bound domain to provider initialization python-sdk#615
• .NET: Supply the bound domain to provider initialization dotnet-sdk#772
• Ruby: Supply the bound domain to provider initialization ruby-sdk#297
• Rust: Supply the bound domain to provider initialization rust-sdk#135
• Kotlin: Supply the bound domain to provider initialization kotlin-sdk#248
• Swift: Supply the bound domain to provider initialization swift-sdk#121
• Docs: Document the bound domain in provider initialization and domain-scoped providers openfeature.dev#1405

[erka]

This is still ambiguous when there are two or more isolated API instances. I also have security concerns about domain infiltration by a malicious feature flag provider.