Flux ArtResuming a download does not mean appending to the old file
When a Flux Art image-result download is interrupted, a custom program can retain a partial file for diagnosis, but must not keep writing just because a temporary file exists. The address may now return another version, or the server may ignore the range request and send the full content. First establish what the existing local bytes belong to, then determine which segment the current response supplies. This article presents a downloader design and acceptance method for an integrating team to implement; no actual download-resumption tests were performed, and it does not promise that any particular result address supports resumption or remains valid long term.
Bind the partial file to its download record first
When saving a temporary file, associate it with the business task, output item, controlled address identifier, actual number of bytes written and version-validation information from the previous response. Keep complete signed addresses only in authorized, controlled locations, not ordinary logs. If a temporary file has no record or its identity is unknown, do not guess which image it belongs to from its filename. Retain it and create a new recovery record, retrieving the complete file again from a permitted source where necessary. Approved assets currently in use must not become append targets, and recovery failures must not damage the currently usable version.
Separate protocol facts from local handling policies
HTTP Range requests partial content; If-Range can request the desired segment if the version still matches, or the complete representation otherwise. Weak ETags cannot be used in If-Range. The protocol basis is the relevant sections of https://www.rfc-editor.org/rfc/rfc9110.html . The table below contains hypothetical branches, not actual tests. The team implements local policies such as pausing or saving separately; unknown responses must not be filled in as expected successes. An ETag is a validator and is not assumed to equal the image's SHA-256.
| Observation during recovery | Local handling approach | What not to do directly |
|---|---|---|
| Version and single-part interval both match | Continue in a controlled temporary object and revalidate | Approve based only on the status code |
| 200 returns full content | Save the full file separately and validate again | Append it to the old partial file |
| 206 has a mismatched interval | Pause and record the actual interval | Ignore gaps or duplicate segments |
| 416 received | Recheck lengths and version | Mark the download complete immediately |
| Identity or coding relationship is unknown | Retain the partial file; retrieve the full file or await verification | Mix offsets from different representations |
Even a partial response requires checking its start and representation
For a single-part 206 response, check the start and end positions, total-length information in Content-Range and actual bytes received; the version evidence must be compatible with the existing fragment. Do not append unconditionally just because the status is 206. Suppose bytes zero through ninety-nine have been saved locally in full: the next segment should start at one hundred. If the response starts at zero or leaves a gap, stop and investigate first. This is an indexing example, not an online test result. If the current implementation does not support multipart responses, explicitly reject that form rather than treating its entire body as the tail of an image.
Save a full response separately, not after the partial file
If a resumption request receives 200, handle it as a full response: write it to a new controlled temporary object and validate it again, rather than appending it to the old fragment. A server that does not support Range or an unmet version condition can invalidate the original continuation plan. Retain the old fragment as evidence of failed recovery until it is handled under internal retention rules; do not reuse unconfirmed bytes merely to make the progress indicator move faster. Obtaining a complete file only completes the transfer checks; it does not establish that business associations or product review have passed.
Assess range errors and content coding separately
Do not interpret 416 as direct proof that the local download is already complete. Check local length, remote length and version before deciding whether to retrieve the whole file again or refer the issue for manual investigation. Also establish which representation's bytes the client saves: if content coding is present and the library automatically decodes it, the old offset may not be directly reusable. This workflow recommends initially supporting one verified, single-part resumption path without content coding. If its conditions are not met, fall back to a full download rather than silently mixing different byte coordinates.
Resource limits and request permissions still apply
Resumed downloads still need limits on total size, time, redirects and attempts; calling the operation resumption does not exempt it from address checks. When a file address expires, use the authorized result-retrieval method. Do not guess signature parameters, bypass permissions or send interface API keys to the image host. Schedule 429 handling according to the actual Retry-After, and retain persistent errors as pending work. Whether to recreate an image is a separate business decision: one failed download must not automatically trigger new generation, nor can recovery be promised to incur no other service charges.
Validate branches without touching production assets
Prepare clearly versioned files in an isolated test environment you control, and test branches including correct segments, Range being ignored with full content returned, version changes, mismatched intervals, range errors and another interruption mid-download. The normal path should restore the same file; abnormal paths should stop appending or retrieve a separate new file, retaining the reason. Do not use customer signed addresses or real keys in tests, or create paid image tasks. Record the client version, sample responses, final hash and failure states; the mere presence of an image that opens at the end does not establish reliable recovery logic.
Final handoff must establish completeness and correct identity
After transfer, perform controlled decoding and content checks on the actual file, associate it with the original business requirement and output item, then move it into asset review. A file hash identifies bytes; it does not replace conclusions about product authenticity or authorization. Flux Art integration documentation is available at https://flux-art.net/en/openapi/reference . Resumption records and state branches are capabilities built by the integrating team, not new platform endpoints. Operated by MORNING STAR INDUSTRY LIMITED, Flux Art is a multi-model AI visual creation and production platform that supports commercial use; confirm input material rights separately.