copilot-session-usage

Extract Copilot session cost KPIs (tokens, estimated USD, model, duration) from local VS Code Copilot debug logs and/or local Copilot CLI/Copilot App session logs.

Full documentation: copilot-session-usage.readthedocs.io

Chronicle and copilot-session-usage

GitHub Copilot provides Chronicle session tools for conversational access to your Copilot history. Chronicle and this project are complementary, but they answer different questions.

What Chronicle is good at

Use Chronicle when you want to:

• Find a past session by its title or session ID.
• Search or summarize what happened in a session.
• Inspect conversational history, checkpoints, referenced files, and session metadata.
• Get a quick, conversational summary of aggregate session KPIs when cost analysis is available in the current Copilot environment.

What Chronicle is not designed to provide

Chronicle's session store is not a token-accounting database. Its stored session records contain history and metadata, but do not expose a standard set of per-request pricing fields. A Chronicle cost answer may therefore provide an aggregate estimate and a list of models without providing a reproducible split of tokens and dollars by model or subagent.

What this project adds

copilot-session-usage reads the original VS Code Copilot debug logs and local Copilot CLI/App event logs and turns them into repeatable reports. It provides:

In the table, ⚠️ means that Chronicle may answer the question in a particular environment or with additional analysis, but does not guarantee a stable, reproducible breakdown for it.

Skill token and cost attribution is limited: VS Code requests are grouped under the latest explicit slash-command skill, including the whole request context and later work until another invocation. This is not an isolated measurement of tokens or cost caused by the skill; automatically loaded and overlapping skills cannot be separated. CLI/App per-skill tokens and costs are unavailable. See Skill attribution.

Use Chronicle for “What did I do?” and use this project for “How much did it cost, which model or subagent consumed it, and can I export the evidence?”

Providers

copilot-session-usage supports two local session sources, selected explicitly with --agent (default vscode):

• vscode (default) — VS Code Copilot Chat debug logs.
• cli — Copilot CLI and Copilot App local sessions, stored under ~/.copilot/session-state/<session-id>/events.jsonl. The macOS Copilot App runs a bundled Copilot CLI runtime and uses the same session-state layout.
• all — an explicit, opt-in combined mode that discovers and aggregates sessions from both providers, deduplicated by session UUID. Commands never mix providers unless --agent all is passed. Missing provider roots are ignored, including when both roots are absent.

Both providers share the same model catalog, pricing data, cache rules, and estimated-USD calculation. Copilot CLI/App sessions additionally expose provider-native counters (provider_usage: nanoAiu, premium requests) as separate fields, and never turn missing evidence (for example, a session that has not shut down yet) into a fabricated zero — see diagnostics in the output when data is unavailable.

# Analyze the latest Copilot CLI/App session
copilot-session-usage --agent cli latest

# Analyze a specific Copilot CLI/App session by its session-state directory
copilot-session-usage --agent cli analyze ~/.copilot/session-state/<uuid>

# List and aggregate sessions from both VS Code and Copilot CLI/App
copilot-session-usage --agent all list --format table

Installation

uv tool install copilot-session-usage

Quick start

# Analyze the most recent session
copilot-session-usage latest

# Analyze a specific session by its debug-log directory
copilot-session-usage analyze /path/to/session/debug-logs

# List recent sessions (metadata only)
copilot-session-usage list

# Batch analyze the last 10 sessions
copilot-session-usage batch 10

# Compact total/model/session report for a date span
copilot-session-usage --agent all span \
  --since 2026-07-01T00:00:00Z \
  --until 2026-07-08T00:00:00Z \
  --format table

# Aggregate cost across all sessions matching a PRD path
copilot-session-usage analyze --name "PRD: /path/to/prd" --aggregate --format table

# List sessions in a debug-logs folder with cost columns
copilot-session-usage list --dir /path/to/debug-logs --format table

Features

• Token-level cost estimation — per-model pricing with cache-hit discounts
• Multi-model sessions — correctly handles sessions that call multiple models (e.g. Claude + Kimi)
• Threshold-aware pricing — long-context tier switching (e.g. GPT-5.4 > 272k tokens)
• Subagent cost attribution — tracks runSubagent calls and their token usage
• VS Code and Copilot CLI/App providers — --agent vscode (default), --agent cli, or the opt-in combined --agent all
• Cross-platform — macOS, Linux, Windows, WSL2
• Three output formats — json (default), table, detailed
• Three detail levels — minimal, compact, full
• JSON and table output — machine-readable or human-friendly
• Session filtering — regex match by name, date-range filtering
• Aggregation — roll up costs across many sessions in one command
• Skill-aware cost attribution — detect skills, attribute LLM and tool calls to the active skill
• Skill-source detection — inspect slash commands, discovery events, system prompts, and skill tools
• Skill cost breakdown — per-skill token counts and estimated cost (VS Code provider)
• Tool-call attribution — per-skill/per-subagent tool-call counts
• Title filtering — find sessions by title substring
• Metadata cache — reuse session indexes until the workspace database changes
• Efficiency summaries — cache ratio, model split, cost per 1M tokens
• Field extraction — pull specific values with --query

How it works

VS Code provider (--agent vscode, default)

copilot-session-usage reads VS Code Copilot debug logs stored in ~/Library/Application Support/Code/User/workspaceStorage/ (macOS), %APPDATA%\Code\User\workspaceStorage\ (Windows), or ~/.config/Code/User/workspaceStorage/ (Linux).

Each session directory contains a GitHub.copilot-chat/debug-logs/ folder with JSONL files plus optional system_prompt_*.json and tools_*.json artifacts. The tool parses the JSONL files, extracts token counts per model, applies per-model pricing (including cache-hit discounts and long-context tier switching), and estimates the session cost in USD. Skill detection also reads the optional system-prompt skill list and skill tool definitions. Those artifacts identify available skills; only timestamped slash-command user messages drive the active-skill attribution timeline.

Session metadata from state.vscdb is cached in a small local index keyed by workspace hash. The index stores metadata only, never raw logs or message content, and is invalidated when the source database mtime changes.

Subagent calls (runSubagent) are tracked separately so you can see how much token usage was delegated to helper agents.

Copilot CLI/App provider (--agent cli)

Copilot CLI and the Copilot App store one directory per session under ~/.copilot/session-state/<session-id>/ (override with --session-root). Each session directory has a structured events.jsonl event log — the primary evidence source — plus an optional workspace.yaml sidecar with title, working directory, git branch, and timestamps.

copilot-session-usage also accepts an explicit session directory or a relocated/exported events.jsonl file directly (for example copilot-session-usage --agent cli analyze /path/to/exported/events.jsonl), without requiring auto-discovery. An explicit source is only analyzed when it contains recognizable Copilot CLI event records and a canonical session UUID can be determined (from the directory name or a session.start event) — otherwise it is rejected with an actionable error instead of being analyzed with a fabricated identity.

Per-model token totals and cost come from the session's final session.shutdown event and use the same shared, token-based pricing calculation as the VS Code provider. GitHub Copilot's own totalNanoAiu billing figure is kept separate under provider_usage.total_nano_aiu and never substituted into the shared cost calculation. For a session that has not shut down yet (still active, or interrupted), only provider-native counters from the last usage checkpoint are available; token totals and cost are reported as unavailable (null) via the shared total block, with diagnostics explaining why, rather than as fabricated zeros. Tool calls and skill attribution are scoped to the subagent that made them, using subagent.started/subagent.completed events and each event's agentId; provider_usage.subagents separately preserves the raw per-subagent evidence available (name, model, tool-call count, reported tokens, duration). Parsing tolerates unrecognized event types and schema versions other than the one currently validated, recording a diagnostic instead of failing.

Pricing lookups for --agent cli/--agent all are local-only by default (no runtime pricing refresh attempt over the network), unlike the vscode provider's default daily refresh attempt. Run copilot-session-usage pricing refresh to update pricing explicitly.

Knowledge base

This project includes an OKF knowledge bundle in knowledge/ with structured guidelines for contributors. Validate it with:

just knowledge-validate

Usage

Commands

Analysis options

Global options

Examples

# Full detail for the latest session
$ copilot-session-usage latest --detail full
{
  "session_id": "f5cbde8a-ec40-466f-86e6-f95c343b6c58",
  "session_dir": "/Users/az02065/Library/Application Support/Code/User/workspaceStorage/c016ff4fabbe9f918719a00c9c741058/GitHub.copilot-chat/debug-logs/f5cbde8a-ec40-466f-86e6-f95c343b6c58",
  ...
}

# JSON output for a specific session
$ copilot-session-usage analyze /path/to/debug-logs --format json --output report.json

# Find sessions containing "implem" in the title
$ copilot-session-usage find "implem"
Multiple sessions match 'implem':
  2026-07-01T21:15:12Z  'Implement copilot-session-usage spec'  (id: c890dd60-43d6-44f0-b57c-ab505dfa003b)
  2026-06-26T18:21:21Z  'Resume PRD implementation'  (id: 9368ab3e-1c93-4125-8271-d5bd024b057a)
  2026-06-26T09:19:52Z  'Resume Workflow PRD implementation'  (id: 1214eb3f-add0-41a5-84d4-88720218e60e)
...

# Get summary for a given session (found by `find`)
$ copilot-session-usage id 19e03be0-9cfa-4f21-a19a-4bdb754b3965 --format table
Session:   19e03be0-9cfa-4f21-a19a-4bdb754b3965
Title:     Implementation of new feature X
Started:   2026-07-01T20:37:34Z
Duration:  40588s  (active: 1083s)
Models:    claude-sonnet-4.6, claude-haiku-4.5, Kimi-K2.6-azure
Input:     1,425,790 tokens
Output:    22,166 tokens
Cached:    1,224,340 (86%)
LLM calls: 28
Est. cost: $1.0880
# Per-skill cost breakdown
$ copilot-session-usage id 19e03be0-9cfa-4f21-a19a-4bdb754b3965 --skill-breakdown --format table
Per-Skill Breakdown:
  Skill                              Input      Cached  Output  Calls     Cost
  ----------------------------------------------------------------------------
  /compendium-generic get-session-costs  1,137,864  1,015,825  15,729     24  $0.3636

# Per-skill/per-subagent tool-call counts
$ copilot-session-usage id 19e03be0-9cfa-4f21-a19a-4bdb754b3965 --tool-breakdown --format table
Tool Breakdown:
  Tool                          Calls  Skill                         Subagent
  ---------------------------------------------------------------------------
  read_file                        25  /compendium-generic get-session-costs  main
  vscode_askQuestions               3  /compendium-generic get-session-costs  main
  runSubagent                       1  /compendium-generic get-session-costs  main

# Concise skill cost (great for scripts)
$ copilot-session-usage id 19e03be0-9cfa-4f21-a19a-4bdb754b3965 \
    --skill "/compendium-generic get-session-costs" \
    --format json --detail minimal
{
  "skill": "/compendium-generic get-session-costs",
  "cost_usd": 0.3636,
  "input_tokens": 1137864,
  "output_tokens": 15729,
  "cached_tokens": 1015825,
  "llm_calls": 24
}

# List skills used across the last 7 days
$ copilot-session-usage skills --last 7d --format table
Skills across 23 sessions:
  Skill                              Sessions        Input     Output       Cached   Calls       Cost
  ---------------------------------------------------------------------------------------------------
  /compendium-generic get-session-costs       3    1137864      15729      1015825      24  $0.3636

# Filter sessions by title substring
$ copilot-session-usage list --title "get-session-costs"
$ copilot-session-usage analyze --title "grill-me" --latest
# Batch analyze last 5 sessions since July 1st
copilot-session-usage batch 5 --since 2026-07-01

# Aggregate all PRD-related sessions from the last week
copilot-session-usage analyze \
  --name "PRD: /path/to/prd" \
  --since 2026-06-30T00:00:00Z \
  --until 2026-07-07T00:00:00Z \
  --aggregate \
  --format table

# Cost-efficiency summary for a single session
copilot-session-usage analyze /path/to/debug-logs --summary --format table

# Extract just the total cost from a session
copilot-session-usage analyze /path/to/debug-logs --query .total.estimated_usd

# WSL2: point to Windows host workspaceStorage
copilot-session-usage latest \
  --workspace-storage /mnt/c/Users/$USER/AppData/Roaming/Code/User/workspaceStorage

Python API

from pathlib import Path

from copilot_session_usage.api import (
    analyze_session,
    analyze_latest,
    batch_analyze,
    aggregate_sessions,
    list_sessions,
)

# Analyze a session by path
result = analyze_session(Path("/path/to/debug-logs"), detail="full")

# Analyze the most recent session
result = analyze_latest(detail="compact")

# Batch analyze the last 10 sessions
batch = batch_analyze(10, detail="minimal")

# Aggregate multiple full analyses into one efficiency summary
aggregate = aggregate_sessions([result1, result2])

# List sessions with regex and date-range filtering
sessions = list_sessions(
    name_pattern=r"PRD",
    since="2026-07-01T00:00:00Z",
    until="2026-07-07T00:00:00Z",
)

# Analyze a Copilot CLI/App session, or discover/aggregate across all
# providers with the explicit opt-in agent="all"
cli_result = analyze_session(Path("~/.copilot/session-state/<uuid>"), agent="cli")
combined = list_sessions(agent="all")

Development

# Install dependencies
just dev

# Run tests
just test

# Run full validation
just preflight

# Build docs
just docs

# Serve docs with auto-reload
just docs-serve

License

MIT — see LICENSE.