Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add jabrena/plinth --skill 055-design-parallel-changegit clone --depth 1 https://github.com/jabrena/plinthWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/jabrena/plinth/055-design-parallel-change)<a href="https://agentmods.dev/skills/jabrena/plinth/055-design-parallel-change"><img src="https://agentmods.dev/badge/skills/jabrena/plinth/055-design-parallel-change/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/jabrena/plinth/055-design-parallel-change"><img src="https://agentmods.dev/badge/skills/jabrena/plinth/055-design-parallel-change.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00094 | $0.00882 |
| Opus 5 | $0.00047 | $0.00441 |
| Sonnet 5 | $0.00019 | $0.00176 |
| Haiku 4.5 | $0.00009 | $0.00088 |
Grade A, and why
055-design-parallel-change scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 10d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 72 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Parallel Change Design
Guide Java Enterprise developers through Parallel Change for database migration scenarios. This is an interactive SKILL.
What is covered in this Skill?
- Deciding whether a database migration needs a compatibility window
- Sequencing database changes as expand, migrate, and contract deployable steps
- Preserving old and new application versions during rollout and rollback windows
- Handling column renames, type or data reinterpretation, large backfills, relationship-table changes, and index or uniqueness changes
- Explaining tradeoffs such as temporary dual paths, extra migrations, verification effort, and delayed cleanup
- Routing framework-specific implementation to Spring Boot, Quarkus, or Micronaut Flyway skills after the design approach is clear
Constraints
Use Parallel Change as a database migration design pattern, then hand off implementation details to the framework-specific migration skill when needed.
- MUST read
references/055-design-parallel-change.mdbefore applying Parallel Change guidance - MUST explain expand, migrate, and contract as separate deployable steps when recommending Parallel Change
- MUST decide whether Parallel Change is needed before recommending framework-specific Flyway implementation details
- MUST recommend a simpler single migration when the change is additive, immediately safe, and does not require old and new application versions to coexist
- MUST describe the compatibility, data-preservation, verification, and cleanup tradeoffs of the chosen approach
- MUST use framework-specific Flyway skills for Spring Boot, Quarkus, or Micronaut implementation details after the migration strategy is selected
When to use this skill
- Apply Parallel Change to this database migration
- Use expand migrate contract for this schema change
- Plan a safe column rename migration
- Plan a zero-downtime database migration
- Should this Flyway migration use Parallel Change?
- Design a safe backfill and contract migration
- Decide if this schema change needs a compatibility window
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 10d ago First seen · 72 lines · 94 tokens per session scan A 7d9c5c9da799
055-design-parallel-change is a skill published in the GitHub repository jabrena/plinth (438 stars, last pushed yesterday), licensed Apache-2.0. It adds 94 tokens to every session and 882 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
Other skills, from other repositories
jpa-patterns
JPA/Hibernate patterns and common pitfalls (N+1, lazy loading, transactions, queries). Use when user has JPA performance issues, LazyInitializationException, or asks about entity relationships and fetching strategies.
ecto-patterns
Ecto patterns — schemas, changesets, queries, migrations, Multi, associations, preloads, upserts. Use when editing Repo calls, Ecto.Query, or schema fields. Skip for Ash.
phoenix-contexts
Phoenix context design — creating/splitting contexts, Scope (1.8+), Ecto.Multi, PubSub, routers, plugs, controllers. Use when editing contexts, routers, or designing boundaries.
ecto-n1-check
Detect N+1 query anti-patterns specifically — Repo calls inside Enum/for loops, missing preloads on associations. Use when N+1 is explicitly suspected, NOT for unrelated Ecto questions or wider database performance.
ecto-constraint-debug
Debug Ecto constraint violations - trace triggers, check migrations, find duplicate data. Use when seeing uniqueconstraint, foreignkeyconstraint, or checkconstraint errors.
constraint-debug
Compatibility alias for the Elixir/Phoenix plugin's Ecto constraint debugger. Invoke explicitly with /ecto:constraint-debug.