plumb-minimal-change

plumb-minimal-change is a skill for Claude Code, Codex from plumbkit/plumb. It costs 22 tokens per session (590 once invoked), scanned A, original, MIT.

A checklist for proving that existing code can be reused and that a proposed change is as small as possible. It uses searches, code-structure inspection, and reference tracing before editing.

In plain words
What is it for?
Use it before non-trivial work to trace the relevant flow, find existing helpers and callers, inspect prior decisions, and choose the smallest safe edit.
Why use it?
It reduces duplicate code and prevents broad edits when an existing helper, setting, or dependency already solves the problem.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it before non-trivial work to trace the relevant flow, find existing helpers and callers, inspect prior decisions, and choose the smallest safe edit.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/plumbkit/plumb/plumb-minimal-change
Install

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.

Any agent
npx skills add plumbkit/plumb --skill plumb-minimal-change
Clone the repo
git clone --depth 1 https://github.com/plumbkit/plumb

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for plumb-minimal-change

README.md
[![agentmods](https://agentmods.dev/badge/skills/plumbkit/plumb/plumb-minimal-change.svg)](https://agentmods.dev/skills/plumbkit/plumb/plumb-minimal-change)
Your own site
<a href="https://agentmods.dev/skills/plumbkit/plumb/plumb-minimal-change"><img src="https://agentmods.dev/badge/skills/plumbkit/plumb/plumb-minimal-change.svg" alt="Measured on agentmods" height="20"></a>
Per session 22 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 590 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00022 $0.00590
Opus 5 $0.00011 $0.00295
Sonnet 5 $0.00004 $0.00118
Haiku 4.5 $0.00002 $0.00059

Measured 7d ago against content hash 31452bc6e2f9, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

plumb-minimal-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 7d 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.

internal/cli/skills/plumb-minimal-change/SKILL.md · 45 lines

How it starts

The opening of the file, as written. The whole thing — 45 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Before writing non-trivial code in a codebase that has plumb available, work through this ladder. Each step is evidence, not vibes — cite what the tools actually returned.

1. Trace the flow first

workspace_search / topology_search / file_outline / read_symbol the relevant area before editing anything. Understand what's already there.

2. Ask if this needs code at all

A doc update, a config change, or an existing flag may satisfy the request. Check before reaching for an editor.

3. Search for existing helpers before writing new ones

workspace_search and workspace_symbols for a function/type that already does this; check memory hints (relevant_memories) for prior art or a declined approach.

4. For bug fixes, find every caller

find_references / topology_impact on the broken symbol. Fix the shared root cause once, not each call site separately.

5. Prefer what's already there

Stdlib, platform, or an already-installed dependency beats a new dependency or a custom framework.

6. Use the smallest edit surface that preserves behaviour

Symbol edits (replace_symbol_body, insert_before_symbol/insert_after_symbol, move_symbol) over full-file rewrites. Deletion over new abstraction when it's safe to delete.

7. Verify proportionally

topology_affected to pick the focused tests; run_task for the smallest relevant check. Run the broader verify before claiming done only when the change's scope warrants it.

Before committing, minimal_diff_review(mode="changed") reviews the working diff itself for signs of over-building — a newly-added function with a single call site, a thin forwarding wrapper, a new dependency with a stdlib equivalent, a possible duplicate helper. It is advisory only and never blocks a write; silence is not proof the change is minimal. Its single-use-abstraction finding in particular is capped at Low confidence today, because the call graph behind it is intra-file — a symbol it calls single-use can still have callers in another file. Confirm a Low-confidence single-use finding with find_references before acting on it; do not inline a symbol on this finding alone.

Read the full file on GitHub · 45 lines

Changes

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.

  1. 7d ago First seen · 45 lines · 22 tokens per session scan A 31452bc6e2f9

Subscribe to this mod's changes

plumb-minimal-change is a skill published in the GitHub repository plumbkit/plumb (4 stars, last pushed yesterday), licensed MIT. It adds 22 tokens to every session and 590 once invoked, about $0.0001 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 2026-08-31.

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