[#6] Filebase Upload Helper

[realproject7]

Summary

• P1-1a: lib/filebase.ts — getFilebaseClient() (S3-compatible client for Filebase) and uploadToIPFS(content, key) (uploads UTF-8 text, returns CID from HeadObject metadata)
• P1-1b: uploadWithRetry() — 3 attempts with exponential backoff (1s, 2s, 4s)
• P1-1c: lib/filebase.test.ts — 9 unit tests with mocked S3Client covering success, missing env vars, missing CID metadata, retry success, and retry exhaustion
• Adds @aws-sdk/client-s3 dependency

Fixes #6

Test plan

• vitest run — 22/22 passing (13 content + 9 filebase)
• tsc --noEmit passes
• Integration test with real Filebase credentials (manual)

🤖 Generated with Claude Code

[project7-interns]

Verdict: APPROVE

Summary

The PR matches issue #6 with a focused Filebase helper, retry wrapper, and mocked unit tests. The S3-compatible upload flow, CID lookup, and dependency additions are consistent with the ticket requirements, and CI is passing.

Findings

• None.

Decision

Approve because the implementation is minimal, follows the requested Filebase upload pattern, and I did not find a blocking correctness, security, or migration issue in scope for this ticket.

[project7-interns]

T2b Review: APPROVE

uploadToIPFS — Correctly uses PutObjectCommand + HeadObjectCommand to retrieve CID from Filebase metadata. Content type set properly.

uploadWithRetry — 3 attempts with exponential backoff (1s, 2s, 4s). Loop structure and lastError preservation are clean.

Security — No hardcoded secrets. All credentials from process.env, with immediate throw on missing values. Test uses vi.stubEnv with dummy values.

Tests (9) — Good coverage: client creation (3), upload (3), retry logic (3). Mocking approach is sound.

Scope — Matches issue #6 exactly (P1-1a, P1-1b, P1-1c).

Minor non-blocking observations:

• key parameter doesn't enforce plotlink/ prefix — caller responsibility, acceptable for internal helper
• New S3Client created per call — fine for low-frequency uploads
• Consider forcePathStyle: true per Filebase docs for robustness

No blocking issues.