[hidb4ai]

Which issue or RFC does this PR close?

Introduces RFC #2086 in English and Chinese.

Rationale for this change

PowerContext users need privacy checks and token efficiency at the context layer, using existing context organization and inference boundaries. The design must work without a gateway while leaving a narrow integration contract for PowerContext Gateway and third-party gateways.

What changes are included in this PR?

• Integrate context selection, approved representation, stable reuse and privacy rules into existing context preparation, Builder, inference and applicable DecisionPolicy consumers.
• Require final-input admission and raw-response release checks. Keep mandatory privacy enforcement independent of optional optimization, with explicit unsupported and unknown coverage.
• Separate Core reuse constraints from model/API/deployment-specific native cache adaptation at the final execution adapter. Distinguish provider accounting from actual computation and latency, and evaluate complete task cost.
• Reuse scoped context/continuity operations and propose at most two remote checks, with bounded optional reuse constraints. Preserve the default PreparedContext shape and add no tables, Artifact families, plan resources or generic cache store.
• Define capability limits and contracts for supported SDKs, PowerContext Gateway, third-party final-boundary plugins and verified upstream passthrough routes. Gateway implementation, routing, shared caches and operational governance are outside this RFC.
• Include matching bilingual architecture and invocation diagrams, a gateway-independent vertical slice, remote-contract acceptance and explicit quality/privacy/cost criteria.

Are there any user-facing changes?

Documentation-only design proposal. This PR does not implement runtime behavior, public operations, a gateway, migrations or measured savings.

How was this change tested?

• TMPDIR=/data/codex-tmp PYTHONPATH=tests/e2e/cross_host_work_continuity/fixtures make check
• make docs-test with Node.js 22.22.3 and the repository-pinned pnpm
• Bilingual heading/example/diagram consistency, UTF-8, relative links, existing API/table references and RFC-only diff checks
• Browser rendering and label-bound checks for both architecture diagrams and both sequence diagrams

No real-provider cache or gateway compatibility experiment is claimed by this documentation change.

AI usage statement

OpenAI Codex assisted with architecture analysis, bilingual RFC editing and validation. The changes are documentation only.