[Ricardo-M-L]

Summary

ImageSDK.save(response, { out }) currently appends the destination to its returned list even when the selected image array is missing, empty, or contains an empty string. This reports a file that was never written and creates unnecessary directories. Whitespace-only base64 can also truncate an existing file to zero bytes.

Return no saved paths before touching the filesystem when there is no nonblank single-image payload. Keep the existing multi-image error and valid URL/base64 save behavior.

Validation

• Regression tests fail against the unchanged base, then pass with the fix.
• Focused image SDK tests: 16 passed, 0 failed (6 unrelated generation tests filtered out).
• Two independent review rounds; final offline reviews include URL/base64 bytes, existing files, Unicode whitespace, multi-image errors, and download failures.
• bun run typecheck, bun run lint, bun run build, and git diff --check pass. Lint retains an existing warning in test/sdk/speech.test.ts.
• Full suite on the final patch: 620 passed / 5 failed. A separate clean checkout of the same base had 603 passed / 11 failed, including the detect-region and macOS Zed failures seen on the patch. The final patch run also had a FileSDK base-URL expectation failure; running FileSDK together with all 11 new image-save tests passed (13/13). Full-suite status is not claimed green; the unrelated order/environment-sensitive failures are left out of this focused fix.

Agent-assisted contribution; tests and filesystem assertions use synthetic data and no paid API calls.

---

^{Need help on this PR? Tag @codesmith-bot with what you need.}