ci: add codecov carryforward flag for shielded tests

[QuantumExplorer]

Summary

• Add two Codecov flags in .codecov.yml:
  • rust — main test coverage (always runs, no carryforward)
  • rust-shielded — ZK/shielded test coverage (carryforward: true)
• When a PR doesn't trigger ZK tests, Codecov carries forward the last known shielded coverage instead of treating it as zero
• Fixes misleading negative coverage diffs on PRs that don't touch shielded code
• Adds cargo-llvm-cov instrumentation to the ZK tests job with rust-shielded flag upload

Test plan

• Verify PR coverage diffs no longer show negative from missing shielded coverage
• Verify ZK tests upload coverage with rust-shielded flag when they run
• Verify carryforward works when ZK tests don't run

🤖 Generated with Claude Code

Summary by CodeRabbit

Release Notes

• Chores
  • Enhanced code coverage reporting infrastructure with updated CI/CD pipeline configuration.
  • Improved test coverage tracking for Rust workspace components.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 32eca784-9eef-42c1-a537-567618286844

📥 Commits

Reviewing files that changed from the base of the PR and between d82ca97 and 6c98451.

📒 Files selected for processing (2)

• .codecov.yml
• .github/workflows/tests-rs-workspace.yml

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📝 Walkthrough

Walkthrough

Configuration updates to improve code coverage tracking: .codecov.yml now specifies separate flags for general rust and rust-shielded coverage with different carryforward settings, while the CI workflow in .github/workflows/tests-rs-workspace.yml integrates cargo-llvm-cov for coverage generation with updated test commands.

Changes

Cohort / File(s)	Summary
Codecov Configuration .codecov.yml	Added codecov flags (rust with carryforward disabled and rust-shielded with carryforward enabled) and expanded ignore patterns for test/package directories.
CI Workflow .github/workflows/tests-rs-workspace.yml	Switched codecov flag from rust-mac to rust, added llvm-tools component and cargo-llvm-cov setup, updated ZK/Shielded tests to use cargo-llvm-cov for coverage generation, and added dedicated step for uploading shielded coverage.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐰 With coverage flags now clear and bright,
Our shielded tests bask in LCOV light,
Llvm-tools bring precision true,
Codecov flows with carryforward cue,
CI pipelines sparkle, coverage review!

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title directly and accurately summarizes the main change—adding codecov carryforward flags for shielded tests to prevent misleading coverage diffs.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch ci/codecov-carryforward-flags

📝 Coding Plan

• Generate coding plan for human review comments

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 68.28%. Comparing base (d82ca97) to head (6c98451).
⚠️ Report is 1 commits behind head on v3.1-dev.

Additional details and impacted files

@@             Coverage Diff              @@
##           v3.1-dev    #3287      +/-   ##
============================================
- Coverage     70.42%   68.28%   -2.15%     
============================================
  Files          3293     3293              
  Lines        262598   262598              
============================================
- Hits         184935   179314    -5621     
- Misses        77663    83284    +5621     

Components	Coverage Δ
dpp	56.61% <ø> (-1.82%)	⬇️
drive	74.76% <ø> (-3.44%)	⬇️
drive-abci	81.44% <ø> (-1.49%)	⬇️
sdk	30.34% <ø> (-0.91%)	⬇️
dapi-client	39.08% <ø> (ø)
platform-version	∅ <ø> (∅)
platform-value	39.35% <ø> (ø)
platform-wallet	60.40% <ø> (ø)
drive-proof-verifier	∅ <ø> (∅)

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