diff

A command that compares Claude usage across two time windows, such as this week and last week. It can show which models, projects, and cache patterns explain the difference.

In plain words
What is it for?
Use it to compare weeks, months, or rolling day ranges, focus on one section, include filtered rows, or export the comparison as JSON.
Why use it?
It makes changes between periods easier to spot than reviewing each usage report separately.

Command

Install

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.

agentmods
npx agentmods add commands/omrikais/cctally/diff
Clone the repo
git clone --depth 1 https://github.com/omrikais/cctally
Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 3,286 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00000 $0.03286
Opus 5 $0.00000 $0.01643
Sonnet 5 $0.00000 $0.00657
Haiku 4.5 $0.00000 $0.00329

Measured yesterday against content hash 893f0ebc0114, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

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.

docs/commands/diff.md · 281 lines

How it starts

The opening of the file, as written. The whole thing — 281 lines — stays where its author put it; the contents beside it link to each section on GitHub.

diff

Compare Claude usage between two windows in a single bordered-table render. Answers "what changed between this week and last week — and which models, projects, and cache patterns drove the change?"

Claude cost coverage: Claude dollar and token totals are transcript-derived lower bounds, not exact /usage billing totals. Codex accounting is unaffected.

Quick examples

# This subscription week vs last
cctally diff --a this-week --b last-week

# This calendar month vs last
cctally diff --a this-month --b last-month

# Rolling 7d vs the previous 7d (lengths match by construction)
cctally diff --a last-7d --b prev-7d

# Compare windows of different length (per-day normalization)
cctally diff --a last-7d --b prev-14d --allow-mismatch

# Drill into a single section (skip the others)
cctally diff --a this-week --b last-week --only cache

# Show every row including those filtered as noise
cctally diff --a this-week --b last-week --all

# Machine-readable output
cctally diff --a this-week --b last-week --json | jq

Window grammar

The --a and --b tokens share the same grammar:

Form Meaning
this-week Current subscription week — start at the most-recent reset anchor, end at now.
last-week Previous full subscription week.
Nw-ago Subscription week N resets back from the current (1w-agolast-week).
this-month Current calendar month in the user's local TZ.
last-month Previous full calendar month.
Nm-ago Calendar month N months back.
last-Nd Trailing N days ending at now ([now − Nd, now)).
prev-Nd The N-day window immediately before last-Nd ([now − 2Nd, now − Nd)).
YYYY-MM-DD..YYYY-MM-DD Explicit inclusive date range, interpreted in local TZ.

Subscription-week tokens fall back to the canonical 7-day-multiple offset when no snapshot exists at the target week (same logic weekly uses). If even the earliest anchor is missing, the command exits with diff: no subscription-week anchor available … and exit code 1.

Read the full file on GitHub · 281 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 · 281 lines · 0 tokens per session scan A 893f0ebc0114

Subscribe to this mod's changes

diff is a command published in the GitHub repository omrikais/cctally (5 stars, last pushed 3d ago), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 3,286 tokens. 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.