fix(session): keep cost monotonic across compaction#3663
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…ession # Conflicts: # pkg/runtime/runtime.go
…ession # Conflicts: # pkg/session/migrations.go # pkg/session/migrations_pinned_test.go # pkg/session/session.go
dgageot
approved these changes
Jul 15, 2026
aheritier
added
area/api
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Summary
Fix session cost snapshots that can drop after compaction, for example from
$49to$12, when restored sub-session costs are replaced by a live root-only usage event.Root cause and behavior
OwnCost()replaces the restored total and can display a large dropTotalCost()is used globallyCompaction did not remove billed messages. It emitted the next token-usage snapshot, exposing the mismatch between restore-time
TotalCost()and liveOwnCost()accounting.Implementation
AddLiveSubSessionSessionUsagesession_items.costwith append-only migration023_add_cost_to_session_itemsSessionSummaryEvent,PersistenceObserver,Store.AddSummary, and the remote HTTP APIRegression coverage
Validation
task buildtask lintenv -u HTTP_PROXY -u HTTPS_PROXY -u ALL_PROXY -u http_proxy -u https_proxy -u all_proxy task testgo test -race -count=1 ./pkg/session ./pkg/runtime ./pkg/acp ./pkg/tui/components/sidebar ./pkg/leantui/...The latest full-suite run has one recording-proxy fixture failure in
TestExec_Anthropic_AgentsMd(requested interaction not found), reproduced unchanged onorigin/main; all other packages pass. A full suite on the same patch before the upstream recording fixture changed passed completely.