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 agentmods add skills/hitmandark07/neatcodeai/validating-diffnpx skills add HITMANdark07/neatcodeai --skill validating-diffgit clone --depth 1 https://github.com/HITMANdark07/neatcodeaiWhat 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 | $0.00055 | $0.01834 |
| Opus 5 | $0.00028 | $0.00917 |
| Sonnet 5 | $0.00011 | $0.00367 |
| Haiku 4.5 | $0.00006 | $0.00183 |
Grade A, and why
validating-diff 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.
How it starts
The opening of the file, as written. The whole thing — 157 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Validating Diffs
Overview
The captured ruleset is enforced at meaningful checkpoints, not after every keystroke. This skill is the gate at those checkpoints.
This skill calls the validate_diff MCP tool.
When to call — the right cadence
The right call frequency is 3–8 times per phase, not 1 (too coarse) and not 12+ (too noisy). The pattern is "once per testable behavior" — every time a logical unit reaches a state worth gating on.
Call when:
- A logical unit is complete: a service + its controller + its spec, written and assembled into something that could be tested.
- A TDD cycle finished — failing test → passing implementation → cleanup. After cleanup is the natural validation point.
- About to commit a batch of changes.
- About to tell the user "the change is in" / "ready" / "done".
- About to hand off to the
verifyingskill (which runsvalidate_diffagain as the final gate).
Do NOT call when:
- Writing a test fixture, snapshot, or pure data file. Nothing the engine can flag.
- Mid-TDD red phase, where the implementation file is empty or stub. Nothing decorated yet.
- Mid-refactor with files in inconsistent intermediate states. The transient state will produce false positives that disappear once the refactor lands.
- Writing a single line of formatting / imports / comments. Trivial edits don't shift any rule outcome.
Why not "every file write":
Three concrete costs. (1) During partial multi-file changes, a controller method calling a not-yet-written service method would spuriously trigger edge-forbidden flags that resolve once the second file lands — training the agent to ignore violations in general. (2) TDD-red phases have nothing to validate; calling anyway is theater. (3) Stop-start fragmenting natural reasoning seams reduces flow without catching anything you wouldn't catch at the next checkpoint.
The earlier you call within the right cadence, the cheaper the iteration. But "earlier" means "at the next logical-unit boundary", not "between every two characters typed."
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.
- yesterday First seen · 157 lines · 55 tokens per session scan A ab791b264e47
validating-diff is a skill published in the GitHub repository HITMANdark07/neatcodeai (0 stars, last pushed 3mo ago), licensed MIT. It adds 55 tokens to every session and 1,834 once invoked, about $0.0003 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 2026-08-31.
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