bug: unified session report sorts by ID instead of documented highest cost first #1718

What happened?

ccusage session sorts the unified report by session ID instead of highest cost first. This makes expensive sessions hard to find and contradicts the session guide.

The guide explicitly covers the unified command, then says:

Sessions are sorted by cost (highest first) by default

In my 247-session JSON report, the first row cost about $0.04 while a later row cost $21.22. The rows were ordered lexically by session ID.

Steps to reproduce

With local usage containing multiple sessions whose costs do not follow session-ID order:

npx --yes [email protected] session --offline --json > sessions.json
jq '.session | map({id: .period, cost: .totalCost})' sessions.json
jq '.session | map(.totalCost) | . == (sort | reverse)' sessions.json

The last check returns false for my report. My captured run used --since 20260912 --until 20260913; those filters can be omitted or changed to a window containing your own sessions.

Expected behavior

Unified sessions should default to descending total cost, matching the guide.

The current source explains the discrepancy: the session branch calls sort_rows, which compares period, then agent. For session rows, period is the session ID. Reversing that order still does not rank by cost.

Related: #903 is closed and reported last-activity sorting. This report concerns session-ID ordering in the unified report in 20.0.20.

I'll work on a fix to restore highest-cost-first ordering for unified sessions, with deterministic ties and regression coverage for table and JSON output.

Version

20.0.20 via npm/npx, macOS arm64. Source inspected at 48dfe97f336ae6f7912b4b386116e962e246ae47.