fix(deps): replace yanked chacha20 with SSE2 backend fix

[Rul1an]

Summary

Fixes #2728. Updates only the workspace lockfile from yanked chacha20 0.10.0 to 0.10.2, with the published registry checksum. No other dependency, feature, version or policy changes.

Upstream #579 reported an unavailable SSE4.1 instruction in the SSE2 RNG/legacy backend. #580 fixes the backend; #583 records that 0.10.0 and 0.10.1 were yanked. This is a supported-target dependency repair, not a locally reproduced Assay crash or exploitation claim.

The normal/build dependency path reaches the MCP package through rand -> object_store -> assay-evidence, not only dev dependencies. The locally generated MCP package lock also contains 0.10.2. Existing published v5.5.1 packages are immutable and remain unchanged by this PR.

Verification

Measured at bd8b7697db87bf1fb187a841bd489cc688666dfc, base f1e2fb644688a7768f12479b227ddde5c9328860, worktree /Users/roelschuurkes/wt-codex-2728-chacha20; Rust/Cargo 1.96.0, macOS arm64, one build job and worktree-local target directory.

• cargo fmt --all -- --check and git diff --check: pass.
• cargo test --locked -p assay-evidence -p assay-adapter-api -p assay-core -p assay-mcp-server --lib: 1,405 passed, 0 failed. These are library tests, not a full repository suite.
• cargo test --locked -p assay-mcp-server --tests: 492 passed, 0 failed, 2 ignored across 41 test targets. The two ignored entries are descendant_spawner_helper_process, which is re-executed as a child by its owning tests. This invocation includes the MCP library tests already counted above; the two totals must not be added as unique tests.
• cargo clippy --locked --workspace --all-targets --exclude assay-it --exclude assay-ebpf -- -D warnings: pass.
• cargo tree --locked -p assay-mcp-server --target x86_64-unknown-linux-gnu -e normal,build -i chacha20: fixed version appears on the production dependency path. This is dependency resolution, not an x86 execution test.
• cargo package -p assay-mcp-server --locked --no-verify: archive created and its embedded Cargo.lock inspected. This command is packaging inspection, not a package compilation test or publication.
• Downloaded dependency archive SHA-256 matches the registry and lockfile: 65c35e4b699c7e15ccbe7ee35c005e4fc0a278d22238a2857e6ce2dadeda1b06.
• Normal commit and push hooks completed successfully, including cargo-deny, RustSec audit, workspace clippy and the local Linux cross-target gate. No hooks were disabled. Local hook success is not a substitute for hosted Linux integration or SSE2 execution proof.

Pending Landing Evidence

Independent exact-head review and required GitHub CI/delegated proof are still required. Cargo.lock requires delegated gates=all; no proof on another SHA is accepted. macOS arm64 tests do not execute the SSE2 backend. No local Miri reproduction or full x86 behavioral claim is made.

A follow-up patch release is needed to deliver this fix through published locked installation artifacts. Do not silently relabel v5.5.1 host evidence as a new-release pass.

[coderabbitai]

Important

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[github-actions]

Assay-Runner Lane Check

PASS: delegated runner proof accepted for this PR.

Matched attested delegated proof pack: https://github.com/Rul1an/assay/actions/runs/33429837971

Expected delegated gate: all

Record proof in the PR body or a PR comment using:

Assay-Runner delegated proof:
- gate: all
- run: https://github.com/Rul1an/assay/actions/runs/<run_id>
- sha: bd8b7697db87bf1fb187a841bd489cc688666dfc

Changed-path classification:

• Cargo.lock: runner workflow, CLI, cgroup, or workspace dependency surface requires gates=all

Contract: docs/reference/runner/ci-lanes.md

[github-actions]

Bencher Report

Branch	codex/2728-chacha20-fixed
Testbed	ubuntu-latest-store-code

Click to view all benchmark results

Benchmark	Latency	Benchmark Result milliseconds (ms) (Result Δ%)	Upper Boundary milliseconds (ms) (Limit %)
swc/120xlarge	📈 view plot 🚷 view threshold	9.23 ms (+15.91%) Baseline: 7.97 ms	12.56 ms (73.50%)
swc/500x400b	📈 view plot 🚷 view threshold	30.38 ms (+15.53%) Baseline: 26.30 ms	41.75 ms (72.76%)

🐰 View full continuous benchmarking report in Bencher

[github-actions]

Bencher Report

Branch	codex/2728-chacha20-fixed
Testbed	ubuntu-latest

Click to view all benchmark results

Benchmark	Latency	Benchmark Result milliseconds (ms) (Result Δ%)	Upper Boundary milliseconds (ms) (Limit %)
sr/wc	📈 view plot 🚷 view threshold	54.75 ms (-51.34%) Baseline: 112.51 ms	168.77 ms (32.44%)

🐰 View full continuous benchmarking report in Bencher

[Rul1an]

Exact-head delegated proof accepted

PR #2729 remains at bd8b7697db87bf1fb187a841bd489cc688666dfc.

• Producer: 33429837971, success at that exact head, gates=all, eBPF build enabled.
• All five gate steps succeeded, along with proof-pack construction, subject attestation, bundle retention, upload and cleanup. None of the five gate steps was skipped.
• Artifact 9772242359, assay-runner-delegated-proof-pack-33429837971: downloaded archive SHA-256 03ebcedec90bc5baed2d54d7bfffbf358568842045cca8b141681e499238d2f7 matches GitHub metadata. Retained locally outside temporary storage. ZIP is 139,931 bytes; its listed 84 entries total 523,318 uncompressed bytes. Archive listing is not an additional semantic proof or signature verification.
• Consumer: 33430136909, success. Current commit status lane-check/proof=success, description attested delegated proof accepted: gates=all.

The earlier missing-proof failure is superseded by the accepted current commit status; it is not rerun or relabeled. Central CI still running when checked. Independent exact-head review remains absent, so no ready, auto-merge, merge or release claim.

[Rul1an]

{
  "schema": "assay.review-record.v0",
  "head_sha": "bd8b7697db87bf1fb187a841bd489cc688666dfc",
  "review_completed": true,
  "verdict": "READY",
  "findings": [],
  "no_findings": true,
  "builder": {
    "agent": "codex",
    "instance": "codex/2728-chacha20-fixed"
  },
  "reviewer": {
    "agent": "ruley",
    "instance": "Grok Bot Ruley, independent review delivered 2026-08-31 21:33:04-21:33:05 Europe/Amsterdam",
    "github_login": "Rul1an"
  },
  "independence": {
    "did_not_build": true,
    "did_not_author_governing_spec": true,
    "declaration": "Ruley states he did not write issue #2728, the lock delta, or its governing plan. Codex authored the commit and brief. Writer worktree untouched."
  },
  "relay": {
    "posted_by": "Codex via Rul1an GitHub account",
    "source": "Ruley's actual Grok Bot Desktop response, not Codex self-review",
    "reviewer_posted_to_github": false
  },
  "scope": {
    "base_sha": "f1e2fb644688a7768f12479b227ddde5c9328860",
    "files": ["Cargo.lock"],
    "full_diff_reviewed": true
  },
  "verification": [
    "Start/end wait-gate holds on the exact candidate and base; no drift.",
    "Full delta is Cargo.lock only, +2/-2: chacha20 0.10.0 to 0.10.2 and checksum. Dependency list unchanged; one chacha20 stanza.",
    "Registry reports 0.10.0 and 0.10.1 yanked, 0.10.2 not yanked. Independently downloaded 38197-byte crate SHA-256 matches lock: 65c35e4b699c7e15ccbe7ee35c005e4fc0a278d22238a2857e6ce2dadeda1b06.",
    "Independently inspected RustCrypto/stream-ciphers #579, #580 and #583. Published 0.10.2 changelog names #580; SSE2 backend no longer uses _mm_extract_epi32 and saves counter with _mm_storeu_si128.",
    "Traced HEAD lock route chacha20 <- rand 0.10.0 <- object_store 0.14.1 <- assay-evidence <- assay-mcp-server, also adapter-api/core. rand 0.8.7 and 0.9.2 do not use chacha20.",
    "Retained generated-package lock excerpt carries the same 0.10.2 checksum. Ruley inspected the artifact/logs; he did not rerun packaging or builds.",
    "Delegated producer 33429837971 succeeded on candidate head. Consumer 33430136909 succeeded; its workflow_run head is trusted main f1e2fb64, while the candidate commit status is lane-check/proof accepted: gates=all. Those are distinct provenance roles.",
    "Central CI 33429801222 now succeeds on candidate head. Historical lane-check misses do not supersede the current accepted commit status.",
    "Tag v5.5.1 still locks chacha20 0.10.0. The published release is not fixed by this candidate."
  ],
  "non_claims": [
    "Code READY only. At review time draft/review-record gate blocked merging; Wave 0 remained in progress. Codex must reconcile live final gates before landing.",
    "ARM/macOS tests and hosted Ubuntu success do not establish that the SSE2 backend executed.",
    "Upstream Miri undefined behavior is not a locally reproduced Assay crash.",
    "cargo package --no-verify is package inspection, not compilation. Local writer logs were read, not rerun.",
    "No edits, builds, auth, public post or merge performed by Ruley. Review binds only this exact SHA."
  ]
}

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