Add coverage check to pre-commit script

[Copilot]

Adds code coverage validation as the final step in the pre-commit workflow. The check uses the existing cargo cov-check alias which validates 85% line coverage threshold.

Changes:

• Added coverage check as 6th step in scripts/pre-commit.sh STEPS array
• Follows existing step format: "description|success_message|special_note|env_vars|command"
• Runs after all other checks (linting, tests, E2E tests, documentation)

Implementation:

"Running code coverage check|Coverage meets 85% threshold|(Informational only - does not block commits)||cargo cov-check"

The step integrates with existing error handling (set -euo pipefail) and timing infrastructure, requiring no additional script logic.

Related: Parent Epic #85

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Add coverage check to pre-commit script</issue_title>
<issue_description>Parent Epic: #85

Overview

Add code coverage validation to the pre-commit script (scripts/pre-commit.sh) as the last check in the steps array. The check uses the cargo cov-check alias which validates that coverage meets the 85% threshold and will fail the pre-commit if coverage drops below this level.

Goals

• Make coverage validation part of the pre-commit process
• Provide developers immediate feedback about coverage impact
• Run coverage check last to ensure all other checks pass first (saves time)
• Use existing step infrastructure for consistency

Specifications

Current Pre-commit Structure

The scripts/pre-commit.sh script uses a step-based execution model with an array of checks. Each step follows the format:
"description|success_message|optional_pre_message|optional_env_var|command"

Proposed Change

Add coverage check as the last step in the STEPS array:

"Running code coverage check|Coverage meets 85% threshold|(Informational only - does not block commits)||cargo cov-check"

Why This Approach?

Advantages:

• ✅ Consistent: Follows existing script patterns
• ✅ Simple: Just one line added to the array
• ✅ Maintainable: No special-case logic needed
• ✅ Clear: Uses same messaging format as other steps
• ✅ Automatic timing: Built-in timing display like other steps

Behavior:

• Runs last after all other checks pass
• Still fails fast if coverage is below 85% (exits with non-zero code)
• Shows clear error message from cargo cov-check
• Uses existing error handling and timing infrastructure

Implementation Plan

Phase 1: Add Coverage Step (5 minutes)

• Open scripts/pre-commit.sh
• Locate the declare -a STEPS=() array
• Add new line at the end of the array (before the closing parenthesis)
• The new line should be:

"Running code coverage check|Coverage meets 85% threshold|(Informational only - does not block commits)||cargo cov-check"

• Save the file

Phase 2: Testing (10 minutes)

• Run ./scripts/pre-commit.sh on current codebase (coverage should pass at 85.75%)
• Verify coverage check runs last (after E2E tests)
• Verify timing is displayed correctly (uses existing timing infrastructure)
• Verify success message appears when coverage passes
• Verify script shows clear output from cargo cov-check

Acceptance Criteria

• Coverage check added as last step in STEPS array in scripts/pre-commit.sh
• Uses cargo cov-check alias (already exists in .cargo/config.toml)
• Success message reads: "Coverage meets 85% threshold"
• Pre-message reads: "(Informational only - does not block commits)"
• Script exits with non-zero code if coverage is below 85%
• Timing information is automatically displayed (inherited from step infrastructure)
• All existing checks still work correctly

Notes

• Running coverage last ensures developers don't waste time waiting for coverage if linting fails
• The coverage check will fail fast and block commits if coverage drops below 85%</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add coverage check to pre-commit script #86

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[josecelano]

ACK d225208