Borrowing it
Nothing to install: this file belongs to rajbos/ai-engineering-fluency. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/rajbos/ai-engineering-fluency/main/.claude/skills/validate-model-pricing/SKILL.mdgit clone --depth 1 https://github.com/rajbos/ai-engineering-fluencyWrote 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/rajbos/ai-engineering-fluency/validate-model-pricing)<a href="https://agentmods.dev/skills/rajbos/ai-engineering-fluency/validate-model-pricing"><img src="https://agentmods.dev/badge/skills/rajbos/ai-engineering-fluency/validate-model-pricing/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/rajbos/ai-engineering-fluency/validate-model-pricing"><img src="https://agentmods.dev/badge/skills/rajbos/ai-engineering-fluency/validate-model-pricing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00102 | $0.01145 |
| Opus 5.5 | $0.00041 | $0.00458 |
| Sonnet 5.5 | $0.00020 | $0.00229 |
| Haiku 4.5 | $0.00010 | $0.00114 |
Grade A, and why
validate-model-pricing 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 — 104 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Validate Model Pricing Skill
Scans recent local AI-coding session log files (and Copilot Chat debug logs) for
every model ID that was actually used, then cross-references that list against the
keys in src/modelPricing.json.
It answers two questions:
-
Are there models in my session logs with no pricing entry? Models that appear in log files but have no key in
modelPricing.jsonfall back togpt-4o-minipricing — which may over- or under-estimate cost significantly. These are reported as UNKNOWN (informational; not an error). -
Are there pricing entries that were never seen locally? Keys in
modelPricing.jsonthat don't match any log file model ID are reported as UNUSED LOCALLY (informational; they may be used by other machines or team members).
Relationship to Other Skills
This skill reuses the same file discovery patterns as the
validate-session-schemas skill — it
covers the same set of file-based platforms:
| Platform | Files scanned |
|---|---|
| Copilot Chat (VS Code) | workspaceStorage/*/chatSessions/*.{json,jsonl}, globalStorage/github.copilot-chat/**/*.{json,jsonl} |
| Copilot CLI | ~/.copilot/session-state/**/*.{json,jsonl} |
| JetBrains Copilot | ~/.copilot/jb/**/partition-*.jsonl |
| Claude Code | ~/.claude/projects/**/*.jsonl |
| Gemini CLI | ~/.gemini/tmp/**/session-*.jsonl |
| Antigravity | ~/.gemini/antigravity/brain/**/.system_generated/logs/transcript.jsonl |
| OpenCode | <XDG_DATA_HOME>/opencode/storage/session/**/ses_*.json |
| Debug logs | workspaceStorage/*/GitHub.copilot-chat/debug-logs/*/main.jsonl |
Debug logs use llm_request JSONL events that contain an attrs.model field — this
is the most authoritative source of model IDs for VS Code chat sessions.
Usage
# Default: scan last 30 days, at most 20 files per platform
node .github/skills/validate-model-pricing/validate-model-pricing.js
# Widen the look-back window
node .github/skills/validate-model-pricing/validate-model-pricing.js --days 90
# Scan more files per platform
node .github/skills/validate-model-pricing/validate-model-pricing.js --max 50
# Machine-readable JSON output
node .github/skills/validate-model-pricing/validate-model-pricing.js --json
# Show all models from logs, even those that do match a pricing entry
node .github/skills/validate-model-pricing/validate-model-pricing.js --verbose
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 · 104 lines · 102 tokens per session scan A 6b1be476701e
validate-model-pricing is a skill published in the GitHub repository rajbos/ai-engineering-fluency (119 stars, last pushed yesterday), licensed MIT. It adds 102 tokens to every session and 1,145 once invoked, about $0.0004 per session on Opus 5.5. 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 2026-10-26.
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