Drift canary
Compatibility and schema drift canary — checks for database schema migration safety, breaking API contract changes, serializable payload mismatches, and backward compatibility drift. Triggers on keywords: "/drift-canary", "drift-canary", "contract drift", "breaking changes". Use when changing DB schemas, API contracts, serialized payloads, or required config keys.From its SKILL.md
npx -y skills add HetCreep/CoalMine --skill drift-canaryAssembled from the repository path, not quoted from the project. Check it against their README if it does not work.
One thing to look at
- 11 stars11 stars. Stars are a popularity signal and not a quality one, but at this level it is likely that nobody has read this closely except its author, and you would be relying on your own review.
SKILL.md
3.1 KB, as published. Nobody here has run it
Drift Canary (Contract & Schema Drift Audit)
<!-- SHARED:LANGUAGE_HEADER -->Audit code to ensure changes do not break backward compatibility or cause database/API mismatches.
Auditing Categories
- Breaking Schema Migrations — dropping columns, changing types, or adding non-null columns without defaults (crashes on deploy).
- API Contract breaking changes — modifying existing REST/GraphQL properties, removing endpoints, or adding required query fields that break old clients.
- Serialization mismatches — editing properties in serialized payloads (JSON, Protobuf, XML) without deserialization fallbacks.
- Library Contract Drift — changing a public method signature in a shared library without a deprecated wrapper.
- Environment Configuration drift — introducing new required config keys (
.env/ OS vars) without defaults or fallback.
Expand/contract migration rules, per-format serialization fallbacks, and the breaking-vs-additive API checklist: read references/checks.md before scanning.
Scope: honor .coalmine.json schemaPaths / migrationDirs if set — scan those globs/dirs; else infer by inspecting the repo.
Discipline
- Style Drift Resolution (Fix mode): when an approved fix touches mixed-style code, conform the minority patterns to the dominant style (highest average usage) to minimize churn — never start a standalone style refactor.
Fix mode (choice-gated)
In Agent Context, after the report, present via ask_question:
- Apply safe deprecations: mark endpoints/methods deprecated + add backward-compatibility mapping wrappers. Each fix: checkpoint (git stash/commit in a git repo; else copy the file aside — never assume git) → apply → build + tests → auto-revert if newly red.
- Let me pick: user selects specific compatibility fixes.
- Report only: exit unchanged.
Grants & denials (CLASSIFY-BLOCK)
| class | step it powers | grant | on denial |
|---|---|---|---|
| read | scan schema/API/serialization surfaces for the categories above | Read·Grep·Glob | refuse that file, name it — never a clean bill |
| write | Fix mode's deprecation/compat-wrapper apply, incl. checkpoint → build+tests → auto-revert if newly red | Edit·Bash (checkpoint/build/revert need exec) | report the fix as NOT applied AND the checkpoint/revert as NOT available, never claim done |
Output
| file:line | contract interface | severity | finding | migration path |
Severity: CRITICAL (breaking DB schema mutation / breaking API change) · HIGH (serialization type change) · MEDIUM (unmapped new required env key) · LOW (missing deprecation doc)
<!-- SHARED:REPORTING_FOOTER --> <!-- SHARED:ORCHESTRATION --> <!-- SHARED:ESCALATION_FOOTER -->What ships with it: 2 files
2.5 KB alongside SKILL.md
references/
- checks.md2.3 KB
- skill-meta.json195 B
Gives 0 of the 12 instructions most databases sql skills give
Counted across 609 of the 712 authors here whose files we hold, read 2026-09-06
- Index all foreign key columnsin 26 of 609
- Use cursor pagination instead of offsetin 25 of 609, across 20 files
- Use timestamptz for timestampsin 21 of 609
- Specify columns instead of using select starin 20 of 609, across 10 files
- Use parameterized queries for all database interactionsin 20 of 609, across 19 files
- Use Enum for categorical datain 17 of 609, across 7 files
- Order by frequently filtered columnsin 17 of 609, across 7 files
- Batch data insertsin 17 of 609, across 7 files
- Use expand-contract pattern for schema changesin 17 of 609
- Use materialized views for real-time aggregationsin 16 of 609, across 6 files
- Partition tables by timein 16 of 609, across 6 files
- Use smallest appropriate data typesin 16 of 609, across 6 files
Said here and by no other author read
- Read references/checks.md before scanning
- Scan schema paths and migration directories
- Conform minority patterns to dominant style
- Checkpoint before applying fixes
- Run build and tests after applying fixes
- Auto-revert if tests fail after fix
Grouped from the skills themselves: near-identical wordings counted once, and counted by distinct author, so one author publishing three of these counts once.