[wylswz]

Summary

Add memory-bounded streaming reads and native byte ranges without changing the existing OSS interface.

• Add optional StreamingOSS.Open(ctx, key, *ByteRange) (io.ReadCloser, error) for Local FS, S3, Aliyun OSS, and Azure Blob.
• Add SupportsStreaming, OpenStream, and an ErrStreamingNotSupported sentinel so callers can explicitly detect capabilities; no implicit full-buffer fallback.
• Support full-object reads, bounded ranges, and offset-to-EOF reads, with range validation, overflow protection, context cancellation, and response Content-Range verification.
• Keep legacy Load compatible and explicitly buffered; close response bodies on success and failure. Azure retains resumable reads with SDK retry support and signed Range options.
• Include hermetic SDK-level tests for streaming behavior, range semantics, cancellation, retries, and resource closure.

PR Stack

1. This PR: streaming API, provider implementations, unit tests, and API documentation (main <- feature/streaming-range).
2. feat(oss): add streaming range reads with integration CI #32: emulator integration infrastructure and PR CI (feature/streaming-range <- test/streaming-integration).

Registered with GitHub native stacked pull requests as stack #34 using gh stack link. This is the bottom PR; #32 is above it. Merge in stack order using GitHub stack controls. Enterprise caller integration is outside these PRs.

Validation

• go test -race -count=1 ./oss/... passes locally.
• S3/LocalStack and Azure/Azurite integration suites pass against the combined stack.
• Storage Integration GitHub Actions check on feat(oss): add streaming range reads with integration CI #32 passes.

Real Azure live validation is not claimed: the attempted test-fixture upload was rejected by data-plane permissions. Emulator tests do not validate Azure RBAC or managed identity.

Compatibility

Existing OSS implementations and consumers remain source-compatible. Backends not implementing StreamingOSS explicitly report no support via the helper. Callers must close returned readers and use streaming APIs rather than Load to avoid whole-object buffering.

[wylswz]

Superseded by #32, which now targets main and contains both the streaming implementation and its integration-test/CI infrastructure. Consolidated so the feature cannot merge separately from the integration checks. No changes were discarded; both commits remain in #32.