!bash "${CLAUDE_SKILL_DIR}/../../hooks/yaml-helper.sh" resolve_config --keys automation,workflow,qa.level,system_overrides

Resolved above — use as-is. No block → defaults in .claude/docs/config-resolution.md.

Regression Suite

This skill ensures that every bug fix is backed by a test that would have caught the original bug — and that the regression suite stays current as the game evolves. It also detects when new features have been added without corresponding regression coverage.

A regression suite is not a new test category — it is a curated list of tests already in tests/ that collectively cover the game's critical paths and known failure points. This skill maintains that list.

Output: tests/regression-suite.md

When to run:

• After fixing a bug (confirm a regression test was written or identify gap)
• Before a release gate (/gate-check polish requires regression suite exists)
• As part of sprint close to detect coverage drift

Every AskUserQuestion call follows .claude/docs/automation-modes.md (collaborative asks always · guided major-only · autonomous logs and proceeds; automation_always_ask categories always prompt).

Workflow tier: modes.workflow as resolved above — supplied by modes.rigor unless set explicitly — per .claude/docs/workflow-modes.md; in audit mode consider workflow_overrides.system_overrides.<system> per system as each GDD is read. It sets whether GDD critical paths are mapped or coverage is smoke-only — see Step 2c.

qa.level: controls whether the suite is generated at all. At minimal, the regression suite is not generated (report that and stop); at standard, generate it at Polish-stage entry; at full, at Production-stage entry. Distinct axis from workflow.

1. Parse Arguments

Early qa.level guard (resolved above): if qa.level: minimal, the regression suite is not generated — report "Regression suite not generated at qa.level minimal" and STOP here, before any scan, in every mode (update / audit / report). This is the qa.level axis; it is distinct from the workflow-tier minimal branch in Step 2c (which only changes the critical-path source, not whether the suite runs). Do not enter Step 2c's minimal branch on account of qa.level.

Modes:

• /regression-suite update — scan new bug fixes this sprint and check for regression test presence; add new tests to the suite manifest
• /regression-suite audit — full audit of all GDD critical paths vs. existing test coverage; flag paths with no regression test
• /regression-suite report — read-only status report (no writes); suitable for sprint reviews
• No argument — if a sprint is clearly active (sprint plan exists with in-progress stories), run update. If ambiguous or no active sprint is detected, use AskUserQuestion:
  • Prompt: "No subcommand specified. Which mode do you want to run?"
  • Options:
    • [A] update — scan new bug fixes this sprint and add missing regression tests
    • [B] audit — full audit of all GDD critical paths vs. existing test coverage
    • [C] report — read-only status report (no writes)

2. Load Context

Step 2a — Load existing regression suite

Read tests/regression-suite.md if it exists. Extract:

• Total registered regression tests
• Last updated date
• Any tests flagged as STALE or QUARANTINED

If it does not exist: note "No regression suite found — will create one."

Step 2b — Load test inventory

Glob all test files:

tests/unit/**/*_test.*
tests/integration/**/*_test.*
tests/regression/**/*

For each file, note the system (from directory path) and file name. Do not read test file contents unless needed for name-to-test mapping.

Step 2c — Load GDD critical paths

For audit mode: read design/gdd/systems-index.md to get all systems, then scope the scan by each system's workflow tier (resolved above):

• full — read the GDD and map critical paths from all sections.
• standard — same, from the required sections (Acceptance Criteria, Edge Cases, and Formulas where the system defines numeric rules). A system pinned higher via system_overrides is mapped at its higher tier.
• minimal — skip the GDD critical-path scan. Instead read the latest smoke-check report in production/qa/smoke-*.md and take the critical paths it exercises as the regression scope (Step 3 maps coverage against those, not GDD acceptance criteria). If no smoke report exists, report that and stop — there is no critical-path source at minimal without one.

(Tier affects audit mode only; update and report modes are tier-independent.)

For each in-scope MVP-tier system's GDD, extract:

• Acceptance Criteria (these define the critical paths)
• Formulas section (formulas must have regression tests)
• Edge Cases section (known edge cases should have regression tests)

For update mode: skip full GDD scan. Instead read the current sprint plan and story files to find stories with Status: Complete this sprint.

Step 2d — Load closed bugs

Glob production/qa/bugs/*.md and filter for bugs with a Status: Closed or Status: Fixed field. Note:

• Which story or system the bug was in
• Whether a regression test was mentioned in the fix description

3. Map Coverage — Critical Paths

For audit mode only. (At minimal the critical paths come from the smoke-check report identified in Step 2c, not from GDD acceptance criteria — map coverage against those smoke paths and skip the GDD-criterion loop below.)

For each GDD acceptance criterion, determine whether a test exists:

1. Grep tests/unit/[system]/ and tests/integration/[system]/ for file names and function names related to the criterion's key noun/verb
2. Assign coverage:

3. Elevate MISSING items that correspond to formulas or state machines to HIGH PRIORITY gap — these are the most likely regression sources.

4. Map Coverage — Fixed Bugs

For each closed bug:

1. Extract the system slug from the bug's metadata
2. Grep tests/unit/[system]/ and tests/integration/[system]/ for a test that references the bug ID or the specific failure scenario
3. Assign:
   • HAS REGRESSION TEST — a test was found that would catch this bug
   • MISSING REGRESSION TEST — bug was fixed but no test guards against recurrence

For MISSING REGRESSION TEST items:

• Flag them as regression gaps
• Suggest the test file path: tests/unit/[system]/[bug-slug]_regression_test.[ext]
• Note: "Without this test, this bug can silently return in a future sprint."

5. Detect Coverage Drift

Coverage drift occurs when the game grows but the regression suite doesn't.

Check for drift indicators:

• Stories completed this sprint with no corresponding test files in tests/
• New systems added to systems-index.md since the last regression-suite update
• GDD sections added or revised since the regression suite was last updated (use Grep on GDD file modification hints if available, or ask the user)
• tests/regression-suite.md last-updated date vs. current date — if gap > 2 sprints, flag as likely stale

6. Generate Report and Suite Manifest

Report format (in conversation)

## Regression Suite Status

**Mode**: [update | audit | report]
**Existing registered tests**: [N]
**Test files scanned**: [N]

### Critical Path Coverage (audit mode only)
| System | Total ACs | Covered | Partial | Missing | Exempt |
|--------|-----------|---------|---------|---------|--------|
| [name] | [N] | [N] | [N] | [N] | [N] |

**Coverage rate (non-exempt)**: [N]%

### Bug Regression Coverage
| Bug ID | System | Severity | Has Regression Test? |
|--------|--------|----------|----------------------|
| BUG-NNN | [system] | S[N] | YES / NO ⚠ |

**Bugs without regression tests**: [N]

### Coverage Drift Indicators
[List new systems or stories with no test coverage, or "None detected."]

### Recommended New Regression Tests
| Priority | System | Suggested Test File | Covers |
|----------|--------|---------------------|--------|
| HIGH | [system] | `tests/unit/[system]/[slug]_regression_test.[ext]` | BUG-NNN / AC-[N] |
| MEDIUM | [system] | `tests/unit/[system]/[slug]_test.[ext]` | [criterion] |

Suite manifest format (tests/regression-suite.md)

Before computing coverage, check the denominator. If the GDD glob returns zero critical paths, or the test globs return zero test files, do not emit a percentage — report Coverage: NOT ASSESSED — [no GDDs found | no test files found] and name which side was empty and the skill that produces it (/map-systems and /design-system for GDDs, /test-setup for the test scaffold).

A percentage computed from an empty denominator is not a low score; it is not a number. 0% reads as "measured and terrible" and 100% as "measured and perfect" — both are claims about a comparison that never happened. This is the same defect /scope-check carries a Phase 4 guard against, in the same words: "a percentage computed from no baseline items is not a small number; it is not a number."

A hand-written list of skills required to carry NOT ASSESSED pins what was known when it was written, so a skill added later inherits no obligation and nothing notices. Derive that set rather than enumerating it.

The manifest is a curated index — not the tests themselves, but a registry of which tests should always pass before a release:

# Regression Suite Manifest

> Last Updated: [date]
> Total registered tests: [N]
> Coverage: [N]% of GDD critical paths

## How to run

[Engine-specific command to run all regression tests]

## Registered Regression Tests

### [System Name]

| Test File | Test Function (if known) | Covers | Added |
|-----------|--------------------------|--------|-------|
| `tests/unit/[system]/[file]_test.[ext]` | `test_[scenario]` | AC-N / BUG-NNN | [date] |

## Known Gaps

Tests that should exist but don't yet:

| Priority | System | Suggested Path | Covers | Reason Not Yet Written |
|----------|--------|----------------|--------|------------------------|
| HIGH | [system] | `tests/unit/[system]/[path]` | BUG-NNN | Bug fixed without test |

## Quarantined Tests

Tests that are flaky or disabled (do not run in CI):

| Test File | Function | Reason | Quarantined Since |
|-----------|----------|--------|-------------------|
| (none) | | | |

7. Write Output

Ask: "May I write/update tests/regression-suite.md with the current regression suite manifest?"

For update mode: append new entries; never remove existing entries (use Edit with targeted insertions). For audit mode: rewrite the full manifest with updated coverage data. For report mode: do not write anything.

After writing (if approved):

• For each HIGH priority gap: "Consider creating the missing regression test before the next sprint. Run /test-helpers to scaffold the test file."
• If bug regression gaps > 0: "These bugs can silently return without regression tests. The next sprint should include a story to write the missing tests."
• If coverage drift detected: "Regression suite may be drifting. Consider running /regression-suite audit at the next sprint boundary."

Verdict: COMPLETE — regression suite updated. (If user declined write: Verdict: BLOCKED.)

Collaborative Protocol

Applies in collaborative mode (the default). For guided and autonomous modes, see .claude/docs/automation-modes.md — the rules below describe what collaborative mode requires, not universal behavior.

• Never remove existing regression tests from the manifest without explicit user approval — removing a test that was deliberately written is a regression risk itself
• Gaps are advisory, not blocking — surface them clearly but do not prevent other work from proceeding (except at release gate where regression suite is required)
• Quarantine is not deletion — tests with intermittent failures should be quarantined (noted in manifest) but not removed; they should be fixed by /test-flakiness
• Ask before writing — always confirm before creating or updating the manifest