ci: force HTTP/1.1 + retries for crates.io fetches (fix HTTP/2 download flake)

[andymai]

What

Add [http] multiplexing = false + [net] retry = 10 to .cargo/config.toml so dependency fetches stop reddening CI.

Why

crates.io downloads on the runners intermittently fail with [16] Error in the HTTP2 framing layer while fetching criterion's transitive deps (cast, alloca, oorandom, itertools) and others. Today alone this flaked Coverage, Test, MSRV (1.88), Boolean perf, and WASM Size Report across the render + revolve PRs — each a spurious red that only cleared on a manual re-run.

The fix

• [http] multiplexing = false — cargo uses HTTP/1.1 instead of HTTP/2, sidestepping the HTTP/2 framing fault that causes the resets.
• [net] retry = 10 — retries transient network failures.

Tradeoff

HTTP/1.1 has no connection multiplexing, so cold-cache fetches open more connections (marginally slower). Downloads only happen on a cold cargo cache — almost always CI — so local-dev impact is negligible, and the reliability win removes a recurring class of spurious CI failures + manual re-runs.

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Summary by cubic

Force HTTP/1.1 and add retries for Cargo dependency downloads to stop crates.io HTTP/2 flakiness in CI. This removes intermittent red jobs without affecting local dev.

• Bug Fixes
  • Set [http] multiplexing = false to use HTTP/1.1 for fetches.
  • Set [net] retry = 10 to retry transient network errors.
  • Stabilizes Coverage, Test, MSRV, Boolean perf, and WASM Size jobs; only minor cold-cache slowdown in CI.

^{Written for commit 3243e4d. Summary will update on new commits.}

[Copilot]

Pull request overview

This PR updates the repository’s Cargo configuration to reduce intermittent CI flakes during crates.io dependency downloads by forcing Cargo to avoid HTTP/2 multiplexing and to retry transient network failures.

Changes:

• Configure Cargo to use HTTP/1.1 for registry downloads ([http] multiplexing = false).
• Increase Cargo network retry attempts for transient failures ([net] retry = 10).
• Add inline documentation describing the CI flake and rationale for the settings.

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[cubic-dev-ai]

No issues found across 1 file

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

_{Re-trigger cubic}

[greptile-apps]

Greptile Summary

This PR updates Cargo fetch settings to reduce CI dependency download flakes. The main changes are:

• Disables Cargo HTTP/2 multiplexing so fetches use HTTP/1.1.
• Raises Cargo network retries to 10 for transient download failures.
• Documents the crates.io HTTP/2 framing failures this configuration targets.

Confidence Score: 5/5

Safe to merge.

The change is limited to Cargo network configuration for dependency fetching and does not alter application, library, or build logic.

T-Rex Logs

What T-Rex did

• Reviewed the before state in the cargo-fetch-config log for commit cf1dc6e and confirmed there were no [http] or [net] entries for http.multiplexing or net.retry.
• Checked the after state in the cargo-fetch-config log for commit 3243e4d and confirmed [http] multiplexing = false and [net] retry = 10, parsed as bool and int, with contract_match=True.
• Verified cargo availability by inspecting the cargo-availability proof, which shows cargo is not installed because cargo --version could not run.

_{Ran code and verified through T-Rex}

_{Reviews (1): Last reviewed commit: "ci: force HTTP/1.1 + retries for crates...." | Re-trigger Greptile}

[github-actions]

WASM Binary Size

File	main	PR	Delta
brepkit_wasm.wasm	5.60 MB	5.60 MB	0 KB (0%)

✅ No size change.