[freshtonic]

Layer 4 of the CIP-5203 stack. Implements CIP-5307 (ADR-0014).

• New crate stack-kms-aws: a hand-written AWS KMS JSON client with in-crate SigV4 (no aws-sdk). It wraps the root key with Encrypt and unwraps it with Decrypt. The AAD is bound through EncryptionContext.
• Credentials: static and environment, IRSA, the ECS container endpoint, and IMDSv2 (native only), cached and refreshed before expiry.
• HttpVendorTransport (native, in stack-kms-vendor).
• Tests: SigV4 vectors, recorded fixtures, the contract suite, and a LocalStack job that runs on PRs.
• The crate is staged for crates.io, with release = false.

Decisions are in docs/plans/2026-11-05-key-vendor-backends-decisions.md (CIP-5307 sections).

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[github-actions]

Mutation testing (cargo-mutants, --in-diff, stack-auth + stack-encrypt)

cargo-mutants did not complete (exit ) before producing results. Check the workflow run logs. The gate below will fail.