| name | regression-suite |
| description | Map test coverage to GDD critical paths, identify fixed bugs without regression tests, flag coverage drift from new features, and maintain tests/regression-suite.md. Run after implementing a bug fix or before a release gate. |
| argument-hint | [update | audit | report] |
| user-invocable | true |
| allowed-tools | Read, Glob, Grep, Write, Edit, AskUserQuestion |
| model | sonnet |
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
1. Parse Arguments
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.
For each MVP-tier system, read its GDD and 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:
For each GDD acceptance criterion, determine whether a test exists:
- Grep
tests/unit/[system]/ and tests/integration/[system]/ for file names
and function names related to the criterion's key noun/verb
- Assign coverage:
| Status | Meaning |
|---|
| COVERED | A test file exists that targets this criterion's logic |
| PARTIAL | A test exists but doesn't cover all cases (e.g. happy path only) |
| MISSING | No test found for this critical path |
| EXEMPT | Visual/Feel or UI criterion — not automatable by design |
- 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:
- Extract the system slug from the bug's metadata
- Grep
tests/unit/[system]/ and tests/integration/[system]/ for a test
that references the bug ID or the specific failure scenario
- 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)
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
- 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
