ai-engineering-fluency: Skill for Claude Code

.claude/skills/discover-debug-log-schema/SKILL.md

discover-debug-log-schema is a skill for Claude Code from rajbos/ai-engineering-fluency. It costs 107 tokens per session (1,247 once invoked), scanned A, original, MIT.

A local-file inspector that lists the actual event types and fields in VS Code Copilot Chat debug logs and checks the fields used for exact usage billing.

In plain words
What is it for?
Use it to discover the current log schema, see which fields the extension reads, and verify that token, model, and billing data remain available.
Why use it?
The log format is undocumented and can change silently, causing billing data to fall back to estimates without an obvious error.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

This is rajbos/ai-engineering-fluency's own configuration. It tells Claude Code how to work on ai-engineering-fluency itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything ai-engineering-fluency configures →

Needs its repository: it runs a file that does not travel with it, so clone the repository first. The line is node .github/skills/discover-debug-log-schema/discover-debug-log-schema.js.

Reuse

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.

Copy the file
curl -O https://raw.githubusercontent.com/rajbos/ai-engineering-fluency/main/.claude/skills/discover-debug-log-schema/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/rajbos/ai-engineering-fluency

Made for: Claude Code.

Wrote 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.

agentmods badge for discover-debug-log-schema

README.md
[![agentmods](https://agentmods.dev/badge/skills/rajbos/ai-engineering-fluency/discover-debug-log-schema/github.svg)](https://agentmods.dev/skills/rajbos/ai-engineering-fluency/discover-debug-log-schema)
Your own site
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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.

agentmods 80×15 button for discover-debug-log-schema

Your own site · 80×15
<a href="https://agentmods.dev/skills/rajbos/ai-engineering-fluency/discover-debug-log-schema"><img src="https://agentmods.dev/badge/skills/rajbos/ai-engineering-fluency/discover-debug-log-schema.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 107 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,247 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00107 $0.01247
Opus 5.5 $0.00043 $0.00499
Sonnet 5.5 $0.00021 $0.00249
Haiku 4.5 $0.00011 $0.00125

Measured yesterday against content hash 0d90ff7f70db, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

discover-debug-log-schema 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.

.claude/skills/discover-debug-log-schema/SKILL.md · 106 lines

How it starts

The opening of the file, as written. The whole thing — 106 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Discover Debug Log Schema Skill

Reads VS Code Copilot Chat's debug logs on this machine and reports what is actually in them.

The extension reads copilotUsageNanoAiu out of these logs to bill VS Code Chat sessions exactly rather than estimating — see docs/logFilesSchema/vscode-chat-debug-log-format.md. That format is undocumented by Microsoft, we parse exactly one of its event types, and validate-session-schemas does not cover it. This skill closes that gap.

What it answers

  1. Is the billing contract intact? Are the five llm_request attrs that _eatdlProcessLlmRequest() in src/tokenEstimation.ts depends on (inputTokens, outputTokens, cachedTokens, model, copilotUsageNanoAiu) still present? This matters because a rename fails silently: the parser still returns a result, copilotNanoAiu becomes 0, and every affected session quietly falls back to estimated pricing. No test fails, no error surfaces.
  2. What are we leaving on the table? Every event type and field path in the log, marked PARSED/IGNORED per type and * per field for what the repo reads today. We consume llm_request only; request_start and request_end are known to exist and are parsed by nothing. If those carry timings, per-call latency would be available with no user configuration — nobody has checked.

Usage

Run from the repository root. Dependency-free Node, no build step:

# Default: last 30 days, 10 most-recent logs
node .github/skills/discover-debug-log-schema/discover-debug-log-schema.js

# Every log regardless of age, more files
node .github/skills/discover-debug-log-schema/discover-debug-log-schema.js --days 0 --max 50

# Machine-readable
node .github/skills/discover-debug-log-schema/discover-debug-log-schema.js --json

Options

Flag Meaning
--days N Only files modified within the last N days (default 30; 0 = no limit)
--max N Analyze at most N most-recent log files (default 10)
--include-examples Include truncated example values — may contain prompts and file paths
--json Emit JSON only
--help Usage

Read the full file on GitHub · 106 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 · 106 lines · 107 tokens per session scan A 0d90ff7f70db

Subscribe to this mod's changes

discover-debug-log-schema is a skill published in the GitHub repository rajbos/ai-engineering-fluency (119 stars, last pushed yesterday), licensed MIT. It adds 107 tokens to every session and 1,247 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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