fix(plugin): insights shows the keep-alive saving with the wrong sign #582

Summary

/context-guru:insights shows the keep-alive saving with the wrong sign. When pings save more than they cost, the "Keep-alive pings" row shows a large negative number. The rows also do not add up to the "Saved" headline.

What we found

Example /api/stats waterfall for a 7-day window (rounded numbers):

• Insights shows "Keep-alive pings" as -120 - 60 = -$180.
• The correct row is 120 - 60 = +$60. The flat field keepalive_net_usd agrees.
• With the fix, the rows add up to the headline: 80 + 60 - 6 = 134. Today they do not.

Why it happens

In the waterfall, a saving is a negative delta_usd. levers() in context-guru-plugin/scripts/cg.py negates compaction, but it uses keepalive_saved as it is:

("Keep-alive pings", w.get("keepalive_saved", 0.0) - abs(w.get("keepalive_ping", 0.0))),

Proposal

• Use abs(w.get("keepalive_saved", 0.0)), as the other rows do.
• Make the same fix in the Codex copy, codex-marketplace/plugins/context-guru/scripts/cg.py.
• Add a test: the lever rows must add up to total_saved.

Open questions

• Do cachesplit_saved, decl_filter_saved and self_removed have the same sign problem? They were 0 in the window we looked at.

Blocks

• docs(readme): replace the plugin section with "What's cool" #579 (README revamp). Its insights screenshot shows the wrong row. It is re-rendered after this fix.