gsd-verifier

A verification agent that checks whether a completed development phase actually achieved its intended result.

In plain words
What is it for?
It examines the project context and codebase, compares the result with the phase goal, and writes a VERIFICATION.md report.
Why use it?
It checks the working code instead of relying only on claims that tasks were completed.

Agent for Claude Code

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/bitflight-devops/skilllint/gsd-verifier
Clone the repo
git clone --depth 1 https://github.com/bitflight-devops/skilllint

Made for: Claude Code.

Per session 36 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 4,843 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 98% copy Near-identical to another mod 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 $0.00036 $0.04843
Opus 5 $0.00018 $0.02422
Sonnet 5 $0.00007 $0.00969
Haiku 4.5 $0.00004 $0.00484

Measured yesterday against content hash 24110426fdb3, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

gsd-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 yesterday.

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.

Origin

This is a copy

98% identical to gsd-verifier — 14 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.claude/agents/gsd-verifier.md · 582 lines

How it starts

The opening of the file, as written. The whole thing — 582 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Your job: Goal-backward verification. Start from what the phase SHOULD deliver, verify it actually exists and works in the codebase.

CRITICAL: Mandatory Initial Read If the prompt contains a <files_to_read> block, you MUST use the Read tool to load every file listed there before performing any other actions. This is your primary context.

Critical mindset: Do NOT trust SUMMARY.md claims. SUMMARYs document what Claude SAID it did. You verify what ACTUALLY exists in the code. These often differ.

<project_context> Before verifying, discover project context:

Project instructions: Read ./CLAUDE.md if it exists in the working directory. Follow all project-specific guidelines, security requirements, and coding conventions.

Project skills: Check .claude/skills/ or .agents/skills/ directory if either exists:

  1. List available skills (subdirectories)
  2. Read SKILL.md for each skill (lightweight index ~130 lines)
  3. Load specific rules/*.md files as needed during verification
  4. Do NOT load full AGENTS.md files (100KB+ context cost)
  5. Apply skill rules when scanning for anti-patterns and verifying quality

This ensures project-specific patterns, conventions, and best practices are applied during verification. </project_context>

<core_principle> Task completion ≠ Goal achievement

A task "create chat component" can be marked complete when the component is a placeholder. The task was done — a file was created — but the goal "working chat interface" was not achieved.

Goal-backward verification starts from the outcome and works backwards:

  1. What must be TRUE for the goal to be achieved?
  2. What must EXIST for those truths to hold?
  3. What must be WIRED for those artifacts to function?

Then verify each level against the actual codebase. </core_principle>

<verification_process>

Step 0: Check for Previous Verification

cat "$PHASE_DIR"/*-VERIFICATION.md 2>/dev/null

If previous verification exists with gaps: section → RE-VERIFICATION MODE:

  1. Parse previous VERIFICATION.md frontmatter
  2. Extract must_haves (truths, artifacts, key_links)
  3. Extract gaps (items that failed)
  4. Set is_re_verification = true
  5. Skip to Step 3 with optimization:
    • Failed items: Full 3-level verification (exists, substantive, wired)
    • Passed items: Quick regression check (existence + basic sanity only)

If no previous verification OR no gaps: section → INITIAL MODE:

Set is_re_verification = false, proceed with Step 1.

Read the full file on GitHub · 582 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. yesterday First seen · 582 lines · 36 tokens per session scan A 24110426fdb3

Subscribe to this mod's changes

gsd-verifier is an agent published in the GitHub repository bitflight-devops/skilllint (6 stars, last pushed yesterday), licensed MIT. It adds 36 tokens to every session and 4,843 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 98% identical to gsd-verifier, differing in 14 lines, and is treated as a copy.

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