fix: treat versionsource 412 as success, eliminating ~860 500s/day

[kptdobe]

Problem

Worker logs show ~860 500 responses per 24 hours, all from POST /versionsource/adobecom/da-cc/{locale}/… endpoints hit by the localization pipeline.

Every entry has:

warn: "An error was encountered in a non-retryable streaming request."

A subset also have:

error: "writeAuditEntry failed"
      "PreconditionFailed: At least one of the pre-conditions you specified did not hold."

Root cause

The localization pipeline processes many locales in parallel. Multiple concurrent workers read the same source document, all obtain the same Version UUID from the object's metadata, and all call POST /versionsource with a label at the same moment.

putVersion uses If-None-Match: * to write the version object (so it can only be created once per key). The first caller wins and gets 200. Every subsequent concurrent caller gets a 412 PreconditionFailed from R2, because the version key already exists.

In putObjectWithVersion:

versionCreated = versionResp.status === 200;  // false on 412

Then in postObjectVersionWithLabel:

if (!resp.versionCreated) return { status: 500, error: 'Version was not created' };

This returns 500 even though the version was created — by the first concurrent request.

Fix

Treat 412 from putVersion as "version already exists = created by a concurrent call":

// 412 means the version key already exists — a concurrent request created it first.
// The version IS persisted in R2, so treat it as created.
versionCreated = versionResp.status === 200 || versionResp.status === 412;

Test plan

• Existing test putObjectWithVersion sets versionCreated true when version already existed (putVersion 412 = concurrent race) — updated to assert versionCreated === true
• Existing test postObjectVersion returns 201 when version already exists in R2 (putVersion 412 concurrent race) — updated to expect 201 instead of 500
• New test returns 201 when version PUT gets 412 (concurrent race — version already exists in R2) via postObjectVersionWithLabel — verifies end-to-end that the caller gets 201
• All 368 tests pass, lint clean

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[adobe-bot]

🎉 This PR is included in version 1.7.1 🎉

The release is available on:

• v1.7.1
• GitHub release

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