[shiju-nv]

Summary

The delegated client compared a backend's Confirmed with the launch only on the first confirmation. Credential renewal, the liveness probe and reconnect accepted any Confirmed, and reconnect ignored the replayed Attach reply. This PR checks every Attach and Confirm reply against the launch and documents that both must stay replayable for the whole generation.

Related Issue

Closes #4703

Changes

• crates/openshell-sandbox-backend/src/runtime.rs:
  • BoundaryClient::check_attached and BoundaryClient::launch_confirmation check a reply against the client's runtime descriptor (workload identity, generation, session, resource claims, provisioning evidence). A wrong response variant is rejected, and a mismatch error names the field.
  • First attach and confirm use them, and so do the three replay paths:
    • ensure_current_credential_connection: credential renewal;
    • connection_is_live: the liveness probe;
    • attach_new_channel: reconnect.
  • On a same-connection renewal that returns another launch, the connection is closed and the mediation session cleared.
  • BoundBoundary loses its copies of the launch fields, since the client's descriptor is now the single source.
• proto/sandbox_protocol.proto: Attach and Confirm replays succeed for the whole generation; the supervisor replays them on reconnect, and Confirm alone for renewal and liveness. The client checks every reply.
• Tests:
  • TestGrpcBoundary gains attach_generation.
  • New tests in runtime/tests/credential_renewal.rs:
    • renewal and reconnect each reject a confirmation whose identity, generation (including empty), session, resource claims or provisioning evidence differs; renewal also closes the connection. The cases come from one shared table, and each checks the error names the field;
    • check_attached and launch_confirmation reject the wrong response variant;
    • reconnect whose Attach reports another generation is rejected.

Testing

• Checks appropriate to the affected code and behavior pass
• Unit tests added/updated (if applicable)
• E2E tests added/updated (if applicable)

Checklist

• Follows Conventional Commits
• Commits are signed off (DCO)
• Architecture docs updated (if applicable)

[TaylorMutch]

The centralized validation is the right shape and closes the gap across first confirmation, renewal, liveness, and reconnect. Please address these items before merge:

1. Update the branch onto current main and rerun CI. This head is 30 commits behind, and crates/openshell-sandbox-backend/src/runtime.rs changed in the intervening transport work (#4656).
2. Complete the replay-path test coverage described by #4703. The new tests cover a session mismatch during renewal/reconnect and an Attach generation mismatch. Please also cover resource-claim and provisioning-evidence mismatches across renewal/reconnect, plus wrong response variants for replayed Attach and Confirm. A table-driven validator test can keep this compact, with path-level tests proving the shared validator is called.
3. Keep mismatch diagnostics field-specific. launch_confirmation calls BoundaryConfirmation::validate before its field checks, so an identity mismatch or empty generation currently returns the generic boundary confirmation is incomplete or mismatched error. Please make those errors identify the mismatched field, matching the issue's acceptance criterion and the PR description.

Once those are addressed and CI is green on the updated base, this should be ready for another review.