fix(sdk): handle short reads when loading TDFs from custom readers

[sujankota]

Proposed Changes

• zipstream.readBytes issued a single Read and returned the full buffer even when fewer bytes came back. *os.File and bytes.Reader always fill the buffer, but other io.ReadSeekers passed to LoadTDF (network/blob-backed readers) may legally return short reads. The tail of the manifest or segment was left zeroed, surfacing as a confusing segment signature validation error.
• Switch to io.ReadFull; running out of input early still returns io.EOF, so callers are unchanged.
• Prerequisite for loading TDFs over HTTP range requests (DSPX-5112, part of DSPX-4886).

Checklist

• I have added or updated unit tests
• I have added or updated integration tests (if appropriate)
• I have added or updated documentation

Testing Instructions

• cd sdk && go test ./internal/zipstream -run TestReaderShortReads — reads a zip through a reader that returns one byte per Read. Fails before this change, passes after.
• cd sdk && go test -race ./... passes.
• golangci-lint run --new-from-rev=main in sdk: 0 new issues.

Summary by CodeRabbit

• Bug Fixes
  • Improved reliability when reading archived files from sources that provide data in small chunks. Full file contents and requested slices are now read correctly, reducing the risk of incomplete or missing data.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

• Configuration used: Repository UI
• Review profile: ASSERTIVE
• Plan: Advanced
• Run ID: 0cfb05d8-e0fe-48d7-b6f2-95e8ad9a742b

📥 Commits

Reviewing files that changed from the base of the PR and between 5679545 and 44d9a29.

📒 Files selected for processing: 2

• sdk/internal/zipstream/reader.go
• sdk/internal/zipstream/reader_test.go

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📝 Walkthrough

readBytes now retries short reads until it fills the requested buffer or reaches an error. A new test checks full-file and ranged ZIP data reads with a reader that returns one byte per call.

Changes: ZIP stream short-read handling

Layer / File(s)	Summary
Short-read handling and coverage sdk/internal/zipstream/reader.go, sdk/internal/zipstream/reader_test.go	readBytes uses io.ReadFull and returns io.EOF for EOF and unexpected EOF. A new test checks full-file and ranged reads with a one-byte-at-a-time reader.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Suggested reviewers: dmihalcik-virtru

Merge Risk: ⚪ Minimal · up to 44d9a

No merge-blocking issue is identified; the change is ready for normal checks.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the main change: fixing short reads when loading TDFs from custom readers.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches: 💡 2

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• Resolve merge conflict in branch fix/zipstream-short-reads

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_{A rabbit reads each byte in flight
Then checks the stream from left to right
Full-file digits, range in view
One-byte hops still carry through
The ZIP path reads its payload true}

_{Comment @coderabbitai help to get the list of available commands.}

[sujankota]

Closing: superseded by #4087, which already landed the same io.ReadFull fix in zipstream.readBytes (with stricter io.ErrUnexpectedEOF semantics). #4221 is being rebased onto main without this commit.