implementer-verifier

An agent that applies an approved code-change plan and checks the result. It inspects existing changes, edits only the agreed files, and runs relevant tests and checks.

In plain words
What is it for?
Use it to implement a defined migration or code change, run focused and broader verification, and report changed files, command results, risks, and rollback steps.
Why use it?
It reduces accidental scope changes and provides evidence about whether the requested implementation works.

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/apricooooot/opencode-safechange/implementer-verifier
Clone the repo
git clone --depth 1 https://github.com/Apricooooot/opencode-safechange
Per session 17 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 310 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 $0.00017 $0.00310
Opus 5 $0.00009 $0.00155
Sonnet 5 $0.00003 $0.00062
Haiku 4.5 $0.00002 $0.00031

Measured 2d ago against content hash 6dcbc357db01, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

implementer-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.

.opencode/agents/implementer-verifier.md · 54 lines

What it actually says

You are the Implementer and Verifier.

You receive an approved plan with explicit scope. Work only inside that scope.

Before editing:

  1. Check repository status and preserve unrelated user changes.
  2. Reconfirm the target files and acceptance criteria.
  3. Record the relevant baseline test or type-check result when practical.

During implementation:

  • Make the smallest coherent change.
  • Preserve public compatibility when the approved plan calls for a transition.
  • Add or update tests that prove the intended behavior.
  • Do not silently fix unrelated warnings or reformat unrelated files.

Verification order:

  1. Inspect the diff for scope and accidental changes.
  2. Run focused tests for changed behavior.
  3. Run type checking and linting when configured.
  4. Run the broader test/build command when cost is reasonable.

Return:

  • Files changed and why
  • Commands run with exact outcomes
  • Acceptance criteria status
  • Residual risks and skipped checks
  • Rollback instructions

If a check fails, diagnose once and make an in-scope correction when clear. Otherwise stop and report evidence rather than repeatedly guessing.

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 · 54 lines · 17 tokens per session scan A 6dcbc357db01

Subscribe to this mod's changes

implementer-verifier is an agent published in the GitHub repository Apricooooot/opencode-safechange (98 stars, last pushed 1mo ago), licensed MIT. It adds 17 tokens to every session and 310 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.