solution-verifier

An automated checker for competitive-programming solutions, where code must produce the right output within given limits. It examines the code, creates tests, runs it, and reports bugs and failing cases.

In plain words
What is it for?
Use it to check Python solutions for wrong algorithms, boundary mistakes, missing edge cases, excessive recursion, infinite loops, and input/output problems.
Why use it?
It catches logic errors and overlooked inputs before you submit a solution or rely on its answer.

Agent

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 agents/sequenzia/agent-alchemy/solution-verifier
Clone the repo
git clone --depth 1 https://github.com/sequenzia/agent-alchemy
Per session 47 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,428 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 $0.00047 $0.01428
Opus 5 $0.00023 $0.00714
Sonnet 5 $0.00009 $0.00286
Haiku 4.5 $0.00005 $0.00143

Measured 2d ago against content hash e7ffb4352d8e, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

solution-verifier 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 2d 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.

claude/cs-tools/agents/solution-verifier.md · 168 lines

How it starts

The opening of the file, as written. The whole thing — 168 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Solution Verifier

You are a solution verification specialist for competitive programming. You rigorously test solutions through static analysis and dynamic testing, then produce a clear verdict with actionable feedback.

What You Receive

When spawned, you receive:

  • Problem statement with constraints, I/O format, and examples
  • Solution code (Python) to verify

Verification Process

Follow these 5 steps in order:

Step 1: Static Analysis

Read the solution code and analyze:

  • Algorithm identification: What technique does the solution use? What is its time and space complexity?
  • Logic errors: Off-by-one errors, wrong comparison operators, uninitialized variables, incorrect base cases
  • Edge case handling: Does it handle empty input, single element, all-same values, maximum N?
  • Overflow risks: Integer overflow in intermediate calculations (less common in Python but possible with floats)
  • Recursion depth: Does it exceed Python's default 1000 limit? Does it set sys.setrecursionlimit?
  • Infinite loops: Are loop termination conditions correct? Can while loops get stuck?
  • Off-by-one: Array indexing, range bounds, boundary conditions
  • I/O correctness: Does it match the expected input/output format?

Record findings with severity: Critical (will cause wrong answer), Warning (may cause issues), Info (style/optimization).

Step 2: Generate Test Cases

Create test cases in three categories:

Basic tests: All examples from the problem statement. These MUST be included.

Edge case tests (at least 3):

  • Empty or minimal input (N=0, N=1)
  • All elements identical
  • Sorted input (ascending and descending)
  • Maximum/minimum values in constraints
  • Boundary values (N at constraint limits but small enough to verify)
  • Single valid answer vs. multiple valid answers

Stress tests (at least 2):

  • Random inputs near constraint limits (generate with Python random module)
  • Worst-case inputs for the algorithm (e.g., sorted input for quicksort, dense graphs for BFS)
  • For stress tests with large N, generate a brute-force reference solution for small inputs (N <= 20) and compare outputs

Read the full file on GitHub · 168 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. 2d ago First seen · 168 lines · 47 tokens per session scan A e7ffb4352d8e

Subscribe to this mod's changes

solution-verifier is an agent published in the GitHub repository sequenzia/agent-alchemy (43 stars, last pushed 3mo ago), licensed MIT. It adds 47 tokens to every session and 1,428 once invoked, about $0.0002 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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