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/session-log-data/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/session-log-data)<a href="https://agentmods.dev/skills/rajbos/ai-engineering-fluency/session-log-data"><img src="https://agentmods.dev/badge/skills/rajbos/ai-engineering-fluency/session-log-data/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/session-log-data"><img src="https://agentmods.dev/badge/skills/rajbos/ai-engineering-fluency/session-log-data.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 | $0.00035 | $0.02088 |
| Opus 5.5 | $0.00014 | $0.00835 |
| Sonnet 5.5 | $0.00007 | $0.00418 |
| Haiku 4.5 | $0.00003 | $0.00209 |
Grade A, and why
session-log-data 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 — 202 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Session Log Data Skill
This skill describes the data files that are automatically downloaded into the GitHub Copilot Coding Agent environment during setup. These files are available for analysis, reporting, and debugging tasks.
When to Use This Skill
Use this skill when you need to:
- Analyze Copilot token usage patterns from downloaded data
- Generate reports or summaries from session logs or aggregated data
- Debug token tracking or usage issues using real data
- Understand model usage distribution across a team
- Calculate estimated costs from usage data
Data Availability
These files are only present when the coding agent environment has Azure Storage configured via the copilot GitHub environment. If the files don't exist, Azure Storage is not configured for this repository.
Data Sources
1. Session Log Files — ./session-logs/
What: Raw AI-coding session log files (Copilot Chat, Copilot CLI, Claude Code/Desktop and other supported editors) downloaded from Azure Blob Storage. These contain the full conversation history including prompts, responses, model information, and tool calls.
Structure:
./session-logs/
└── {datasetId}/
└── {machineId}/
└── {YYYY-MM-DD}/
├── session-abc123.json
└── 3a364aa6-b270-4d67-b1df-39841ccb74b0.jsonl
Date range: Last 7 days of session data.
File formats: Files arrive as .json and .jsonl, decompressed from .gz uploads or downloaded as-is when the uploader's blobCompressFiles setting is off. A download contains both formats, and in recent data nearly all of them are .jsonl. Always search for both extensions; a *.json-only search silently skips most sessions.
.jsonl— one JSON event per line. The event shape depends on the editor that wrote it (Claude Code/Desktop, Copilot CLI, VS Code Chat delta logs, ...), so look up the file's editor in the editor type manifest and its schema underdocs/logFilesSchema/. For token and model numbers, prefer the shared parsers in the repo-rootsrc/(estimateTokensFromJsonlSession(),getModelUsageFromSession()) over hand-rolledjq..json— a whole Copilot Chat session in one document, with this structure:
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 · 202 lines · 35 tokens per session scan A 30c85c53fc92
session-log-data is a skill published in the GitHub repository rajbos/ai-engineering-fluency (119 stars, last pushed yesterday), licensed MIT. It adds 35 tokens to every session and 2,088 once invoked, about $0.0001 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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