test(deps): preview build against multistore cross-request-body-io fix

[alukach]

Draft / temporary — not for merge. Exists to deploy a preview for end-to-end verification of the multistore fix.

What this does

Adds a temporary [patch.crates-io] block pointing all five multistore* crates at the fix/cross-request-body-io branch (developmentseed/multistore#100). No app code changes — only Cargo.toml + Cargo.lock.

What the multistore fix does

Resolves intermittent 500/503 failures on multipart and batch-delete writes under a cold-isolate burst:

[ERROR] multistore::proxy: failed to read request body
  error=arrayBuffer await failed: Cannot perform I/O on behalf of a different request

Root cause: the inbound body was read via array_buffer() after the bucket-lookup and STS awaits; wasm-bindgen-futures' shared microtask queue can resume that read under another concurrent request's I/O context. The fix:

• Plain UploadPart now streams (UNSIGNED-PAYLOAD header signing, checksums forwarded+signed) instead of buffering — never materialized.
• Small multipart-control / batch-delete bodies are read at the top of handle_request, in the request's own I/O context, before any cross-request await.

How to verify on the preview

Point the source.coop frontend at this deployment and exercise the cases that reproduced the error:

• A large batch of object deletes (the original report).
• A multipart upload of large objects (e.g. the euro-test Zarr writes) — UploadParts and the multipart control ops.

Expect no Cannot perform I/O on behalf of a different request (500/503) on the opening burst, and parts/deletes to complete.

Cleanup

Revert this commit and bump the multistore* deps once developmentseed/multistore#100 is released.

🤖 Generated with Claude Code

[claude]

Claude finished @alukach's task in 59s —— View job

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Reviewing PR #174

• Gather context (read diff, Cargo.toml/Cargo.lock changes)
• Review for correctness/security/best-practice issues
• Post findings

✅ No blocking issues — safe to merge.

This is a draft/temporary preview PR (explicitly marked "not for merge") that only adds a [patch.crates-io] override pinning the five multistore* crates to a fix branch. The change is mechanical and self-contained:

• Cargo.toml:79-95 — all five multistore* crates (multistore, multistore-cf-workers, multistore-oidc-provider, multistore-path-mapping, multistore-sts) are patched to the same git source/branch, which is required for their shared types to unify — confirmed consistent.
• Cargo.lock — all five entries resolve to the identical commit (b3fc487038ec7c3b55d6f73c095482d68a3f30fb), matching the branch pinned in Cargo.toml, and no unrelated lockfile entries were touched.
• The comment block in Cargo.toml documents the rationale, the temporary nature, and the removal plan (revert + bump once fix: bound buffered-op body size and fail closed on classifier over-match developmentseed/multistore#102 ships in a release), which is good practice for a patch like this.

Minor (non-blocking) note: the PR description still references the original branch name fix/cross-request-body-io, but the code now points at fix/buffered-body-size-guard (per the latest commit history) — just a stale description, not a code issue, and irrelevant once this is reverted post-verification.

No security or correctness concerns: this only affects build-time dependency resolution for the preview deployment and carries no app code changes.

[github-actions]

🚀 Latest commit deployed to https://source-data-proxy-pr-174.source-coop.workers.dev

• Date: 2026-06-30T22:59:25Z
• Commit: 6e8e6fd