Flaky CI Failure: Cache all Nix Outputs — xmtpv3-android derivations fail (2 deps) in Build all flake outputs

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Flaky CI Failure: xmtpv3-android derivations fail (2 dependencies) in Build all flake outputs

Workflow: Cache all Nix Outputs
Failed run: https://github.com/xmtp/libxmtp/actions/runs/28602108813
Commit: ae224c5
Failed jobs: build (warp-ubuntu-latest-x64-16x)

Summary

The Build all flake outputs step failed with 2 Nix dependencies failing, causing devour-output.json.drv to fail. Unlike the related issue #3811 (where ffi-uniffi-bindgen failed due to a rustc panic), in this run ffi-uniffi-bindgen and uniffi-bindgen both completed successfully. The 2 failing dependencies are the Android-specific derivations xmtpv3-android-fast.drv and xmtpv3-android.drv, which appear to fail immediately after starting — the root cause is not visible in the captured log output.

Error Details

build (warp-ubuntu-latest-x64-16x)  Build all flake outputs
  ffi-uniffi-bindgen> buildPhase completed in 7 minutes 28 seconds
  ffi-uniffi-bindgen> Running phase: installPhase
  ffi-uniffi-bindgen> actually installing contents of ... to /nix/store/08b3hqi8br7bhda1z26yj72hw9zk62cr-ffi-uniffi-bindgen-1.11.0-dev

  uniffi-bindgen> Code generation complete, formatting with ktlint
  uniffi-bindgen> Warning: Unable to auto-format xmtpv3.kt using ktlint: Os { code: 2, kind: NotFound, message: "No such file or directory" }

  building '/nix/store/701ms3ycnyv9k5s3c834fva4i7pjrhjb-xmtpv3-android-fast.drv'...
  building '/nix/store/qk3kabgw2wal29zg71hbg0fv8c888pf8-xmtpv3-android.drv'...

error: Cannot build '/nix/store/h8cdkiddlz7myk77ry4fx7x4w2wwdgfd-devour-output.json.drv'.
       Reason: 2 dependencies failed.
       Output paths:
         /nix/store/17cifdd0zjmqdaxwbaq500wcqc8qchrv-devour-output.json

Error: `nix build` failed; exit code: Some(1)
##[error]Process completed with exit code 1.

Analysis

This failure is distinct from #3811:

• In Flaky CI Failure: Cache all Nix Outputs — rustc panics (exit 101) building xmtp_logging in ffi-uniffi-bindgen #3811, ffi-uniffi-bindgen itself failed (rustc panic in xmtp_logging), cascading to 6 failures including the Android derivations.
• In this run, ffi-uniffi-bindgen and uniffi-bindgen both succeed. The 2 Android derivations (xmtpv3-android-fast and xmtpv3-android) fail directly, and they appear to fail almost immediately after starting — suggesting a pre-build or dependency resolution error rather than a compilation timeout.
• The --log-failed output does not capture the internal failure message for these derivations. Inspecting nix log /nix/store/701ms3ycnyv9k5s3c834fva4i7pjrhjb-xmtpv3-android-fast.drv would be needed to determine the root cause.
• This is a build failure, not a transient infrastructure failure (network, disk, registry).

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Reported by Flaky Failure Watcher