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 ArabelaTso/Skills-4-SE --skill semantic-equivalence-verifiergit clone --depth 1 https://github.com/ArabelaTso/Skills-4-SEWrote 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/arabelatso/skills-4-se/semantic-equivalence-verifier)<a href="https://agentmods.dev/skills/arabelatso/skills-4-se/semantic-equivalence-verifier"><img src="https://agentmods.dev/badge/skills/arabelatso/skills-4-se/semantic-equivalence-verifier/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/arabelatso/skills-4-se/semantic-equivalence-verifier"><img src="https://agentmods.dev/badge/skills/arabelatso/skills-4-se/semantic-equivalence-verifier.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 | $0.00086 | $0.01272 |
| Opus 5 | $0.00043 | $0.00636 |
| Sonnet 5 | $0.00017 | $0.00254 |
| Haiku 4.5 | $0.00009 | $0.00127 |
Grade A, and why
semantic-equivalence-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 8d 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 — 188 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Semantic Equivalence Verifier
Overview
This skill enables rigorous analysis of semantic equivalence between two code artifacts (functions, classes, or modules). It systematically compares control flow, data flow, and observable behavior to determine if implementations are functionally identical, and provides actionable guidance for achieving equivalence when differences exist.
Verification Workflow
Step 1: Input Specification
Clearly identify the two code artifacts to compare:
Artifact A: [function/class/module name and location]
Artifact B: [function/class/module name and location]
Specify the equivalence scope:
- Strict equivalence: Identical behavior for all possible inputs
- Partial equivalence: Identical behavior for a specific input domain
- Observable equivalence: Identical externally visible behavior (may differ internally)
Step 2: Static Analysis
Perform systematic static analysis on both artifacts:
Control Flow Analysis:
- Extract control flow graphs (CFG) for both artifacts
- Identify branching conditions, loops, and exit points
- Compare CFG structure and reachability
- Note: Different CFG structures don't necessarily mean non-equivalence
Data Flow Analysis:
- Trace variable definitions and uses
- Identify data dependencies
- Compare computation sequences
- Check for equivalent transformations (e.g.,
x*2vsx+x)
Signature Analysis:
- Compare function signatures (parameters, return types)
- Check preconditions and postconditions
- Verify exception handling behavior
Step 3: Behavioral Analysis
Analyze runtime behavior and observable effects:
Input-Output Mapping:
- Identify representative test inputs covering edge cases
- Compare outputs for identical inputs
- Check boundary conditions and error cases
Side Effects:
- File I/O operations
- Network calls
- Database modifications
- Global state changes
- Memory allocations
Performance Characteristics:
- Time complexity (O-notation)
- Space complexity
- Note: Performance differences don't affect semantic equivalence unless specified
What ships with it
4 files 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.
- 8d ago First seen · 188 lines · 86 tokens per session scan A 7245ea18ad6a
semantic-equivalence-verifier is a skill published in the GitHub repository ArabelaTso/Skills-4-SE (252 stars, last pushed 21d ago), licensed Apache-2.0. It adds 86 tokens to every session and 1,272 once invoked, about $0.0004 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 2026-09-03.
Other skills, from other repositories
remove-ai-slops
Removes AI-generated code smells from branch changes or an explicit file list behind regression tests. Use when the user asks to clean up, deslop, or remove AI-slop patterns from recent changes.
codex-loop
Fix Elixir/Phoenix code until Codex CLI review comes back clean — bounded review, fix, verify loop before opening a PR. Use when codex is installed and you want an external cross-model critic on your changes before pushing.
codex-ab
Run an A/B codex review experiment — holistic codex review vs 3 focused dimension passes (security, ecto, liveview) on the branch diff, classify findings, report a panel-value verdict. Use when the branch is fresh, before any codex review runs.
059-design-atdd
Use when reviewing whether an OpenSpec change's execution goal, acceptance criteria, and implementation or verification tasks are aligned. This should trigger for requests such as Review this OpenSpec change with ATDD; Check acceptance criteria against tasks; Find acceptance criteria without task coverage; Detect…
056-design-avoid-breaking-changes
Use when you need to review a plan, OpenSpec change, specification, or implementation proposal for breaking-change risk across commands, skills, generated outputs, XML sources, README/docs, tests, CI, APIs, schemas, configuration, data, migration, and release guidance. This should trigger for requests such as Review…
053-design-simple-rules
Use when Java design, refactoring, or implementation tradeoffs should be evaluated with Kent Beck's simple design rules, including passes the tests, reveals intention, has no duplication, and has the fewest elements. This should trigger for requests such as Apply simple design rules; Review this design with Beck's…