canary-critical-areas

canary-critical-areas is a skill for Claude Code from bop-clocktower/canary. It costs 55 tokens per session (1,117 once invoked), scanned A, original, MIT.

A risk-ranking helper for codebases and code changes. It combines clues such as recent edits, dependent code, business importance, and existing test coverage to rank areas that deserve attention.

In plain words
What is it for?
Use it before writing tests, after a large code change, or as the first step in a test-planning process to choose areas and test types.
Why use it?
It prevents teams from spreading testing effort evenly when some parts of the code are much more likely to cause serious problems. It also helps identify what a large change may have put at risk.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the canary plugin — 23 skills, 13 commands, 8 agents, 4 hooks shipped together

Good fit Use it before writing tests, after a large code change, or as the first step in a test-planning process to choose areas and test types.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/bop-clocktower/canary/canary-critical-areas
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 bop-clocktower/canary --skill canary-critical-areas
Clone the repo
git clone --depth 1 https://github.com/bop-clocktower/canary

Made for: Claude Code.

Or install canary, the plugin that ships this one along with the rest of its 23 skills, 13 commands, 8 agents, 4 hooks.

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 canary-critical-areas

README.md
[![agentmods](https://agentmods.dev/badge/skills/bop-clocktower/canary/canary-critical-areas/github.svg)](https://agentmods.dev/skills/bop-clocktower/canary/canary-critical-areas)
Your own site
<a href="https://agentmods.dev/skills/bop-clocktower/canary/canary-critical-areas"><img src="https://agentmods.dev/badge/skills/bop-clocktower/canary/canary-critical-areas/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.

agentmods 80×15 button for canary-critical-areas

Your own site · 80×15
<a href="https://agentmods.dev/skills/bop-clocktower/canary/canary-critical-areas"><img src="https://agentmods.dev/badge/skills/bop-clocktower/canary/canary-critical-areas.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 55 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,117 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 $0.00055 $0.01117
Opus 5 $0.00028 $0.00558
Sonnet 5 $0.00011 $0.00223
Haiku 4.5 $0.00006 $0.00112

Measured 11d ago against content hash 1ead98eed65b, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

canary-critical-areas 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 11d 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.

agents/skills/claude-code/canary-critical-areas/SKILL.md · 143 lines

How it starts

The opening of the file, as written. The whole thing — 143 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Canary: Critical Areas

Identifies the highest-risk areas of a codebase so test effort goes where it matters most. Uses multiple signals, degrades gracefully when advanced tooling is unavailable.

When to Use

  • Before writing new tests: "where should I focus?"

  • After a large diff lands: "what did this change put at risk?"

  • As Phase 1 of /canary-test-pipeline

  • When asked to prioritise test coverage

Signals

Collect all available signals, score each area, and rank by composite risk score.

1. Churn / hotspot (always available)

With harness MCP available: call detect_anomalies (metric hotspotScore, plus its co-change / single-point-of-failure signals). Harness's hotspot score already blends churn with structural risk, so use it directly as this signal and skip the raw git log pass. Normalise the returned scores to 0–1.

Fallback (no MCP):

git log --stat --since="90 days ago" -- <path> | grep -c "^"

Files changed most frequently in the last 90 days score higher. Normalise to 0–1 across all files in scope.

2. Downstream dependents

With harness MCP available: call get_impact for each candidate file (filePath, mode: "summary") and read the affected-node counts it returns (tests / docs / code grouped by type). This is the purpose-built impact primitive — do not hand-walk get_relationships edge-by-edge; get_impact already computes the transitive downstream set. More affected nodes ⇒ higher score.

Fallback (no MCP): scan for import statements referencing each file using grep -r. Count unique files that import each candidate.

Files with more inbound dependents score higher — a change here breaks more.

3. Business-critical / critical-path flags

With harness MCP available: call get_critical_paths and add a fixed boost (+0.3) to any area whose functions appear in the returned perf-critical set. Also query ask_graph for business_fact nodes associated with each area; any business-critical annotation adds the same +0.3 boost (apply the boost once, whichever signal fires).

Read the full file on GitHub · 143 lines

Files

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.

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. 11d ago First seen · 143 lines · 55 tokens per session scan A 1ead98eed65b

Subscribe to this mod's changes

canary-critical-areas is a skill published in the GitHub repository bop-clocktower/canary (4 stars, last pushed today), licensed MIT. It adds 55 tokens to every session and 1,117 once invoked, about $0.0003 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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