blast-radius-preview

blast-radius-preview is a skill for Claude Code, Codex from DVNghiem/FlowDeck. It costs 27 tokens per session (481 once invoked), scanned A, original, MIT.

A change-analysis tool that maps the systems, modules, and services likely to be affected by a code change. It also checks integration points, past regression records, and integration-test coverage.

In plain words
What is it for?
Use it before changing shared infrastructure, public APIs, event formats, database models, authentication, or session handling. It produces a report showing direct and indirect effects and possible breakage.
Why use it?
It helps reveal indirect dependencies and fragile connections before a change causes failures elsewhere.

Skill for Claude CodeCodex

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

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.

agentmods
npx agentmods add skills/dvnghiem/flowdeck/blast-radius-preview
Any agent
npx skills add DVNghiem/FlowDeck --skill blast-radius-preview
Clone the repo
git clone --depth 1 https://github.com/DVNghiem/FlowDeck

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 blast-radius-preview

README.md
[![agentmods](https://agentmods.dev/badge/skills/dvnghiem/flowdeck/blast-radius-preview.svg)](https://agentmods.dev/skills/dvnghiem/flowdeck/blast-radius-preview)
Your own site
<a href="https://agentmods.dev/skills/dvnghiem/flowdeck/blast-radius-preview"><img src="https://agentmods.dev/badge/skills/dvnghiem/flowdeck/blast-radius-preview.svg" alt="Measured on agentmods" height="20"></a>
Per session 27 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 481 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00027 $0.00481
Opus 5 $0.00014 $0.00241
Sonnet 5 $0.00005 $0.00096
Haiku 4.5 $0.00003 $0.00048

Measured 6d ago against content hash 3abf95995fd5, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

blast-radius-preview 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 6d 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.

src/skills/blast-radius-preview/SKILL.md · 66 lines

What it actually says

Blast Radius Preview

Before committing to a change, map every system that could break. Activate this skill by providing a change description to the agent.

When to Activate

  • Before merging a change that touches shared infrastructure
  • Before modifying a public API, event schema, or DB model
  • Before changing authentication or session handling
  • Any time the Impact Radar returns HIGH

Workflow

  1. Load the dependency graph from ~/.fd-plan/<slug>/.codebase/MEMORY.json
  2. Start from the directly changed nodes
  3. Walk the graph outward: find all services/modules that depend on the changed node
  4. At each hop, check:
    • Is this an integration point (API call, event subscription, DB query)?
    • Does this path have regression history in ~/.fd-plan/<slug>/.codebase/FAILURES.json?
    • Is this path covered by integration tests?
  5. Flag hidden couplings: shared mutable state, ambient context, feature flags
  6. Produce the blast radius map

Blast Radius Report Format

## Blast Radius Report

### Change
[description]

### Direct Blast (depth 1)
| Module | Coupling Type | Test Coverage | Fragile? |
|--------|--------------|---------------|---------|

### Indirect Blast (depth 2–3)
| Module | Via | Risk Level |
|--------|-----|------------|

### Integration Point Risks
- [endpoint/event]: [why at risk]

### Hidden Couplings
- [module]: shared state / ambient context / feature flag

### Predicted Breakage Categories
- [ ] Performance: [reason]
- [ ] Auth: [reason]
- [ ] Schema: [reason]
- [ ] Async flow: [reason]

### Blast Radius: NARROW | MODERATE | WIDE

Guidance

  • NARROW: ≤3 downstream modules, all covered by tests → safe to proceed
  • MODERATE: 4–10 downstream modules or ≥1 uncovered → add tests before merging
  • WIDE: >10 downstream modules or hits fragile integration → escalate to senior review
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. 6d ago First seen · 66 lines · 27 tokens per session scan A 3abf95995fd5

Subscribe to this mod's changes

blast-radius-preview is a skill published in the GitHub repository DVNghiem/FlowDeck (24 stars, last pushed 17d ago), licensed MIT. It adds 27 tokens to every session and 481 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 2026-08-30.

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