Greptile Summary

This PR introduces session-scoped tracking of discarded assistant responses — tokens spent on replies later removed by edit-and-rerun or regeneration — and exposes them in a new spentTotal field on TotalUsageResult. The ChatHeader tooltip is updated to separate "context (current)", "edited / regenerated", "title generation", and "total spent" breakdowns.

• conversationStore gains discardedUsage / discardedResponseCount state, accumulated in deleteMessagesAfter and replaceAssistantMessage, and reset on every conversation switch, clear, or setMessages.
• useTotalUsage now reads those fields plus titleGenerationUsage from the store and derives spentTotal = grandTotal + discarded + titleGeneration; it returns null only when spentTotal.totalTokens === 0.
• A new vitest suite covers the happy path, mode-overhead accumulation, zero-usage skipping, and multi-discard accumulation; the Storybook helper is updated to mirror the real computation.

Confidence Score: 5/5

Safe to merge — the discard tally is accumulated correctly, reset on every conversation boundary, and never mutates existing state in place.

The accumulation logic in mergeDiscarded always starts from a fresh emptyUsage copy of the current state, so store updates cannot corrupt the tally. Both entry-points capture the old message reference before reassigning the array slot. Reset paths cover all conversation-change surfaces and test coverage is thorough.

No files require special attention.

Important Files Changed

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[User edits or regenerates] --> B{Which action?}
    B -->|deleteMessagesAfter| C[Slice removed messages]
    B -->|replaceAssistantMessage| D[Capture old message ref]
    C --> E[mergeDiscarded: fold usage + mode overhead]
    D --> E
    E --> F[discardedUsage accumulates\ndiscardedResponseCount++]
    F --> G[Store update: new discardedUsage object]
    H[setMessages / clearMessages\n/ setCurrentConversation] --> I[Reset discardedUsage = emptyUsage\ndiscardedResponseCount = 0]
    G --> J[useTotalUsage re-runs]
    I --> J
    J --> K[grandTotal = total + modeOverhead\nspentTotal = grandTotal + discarded + titleGeneration]
    K --> L{spentTotal.totalTokens == 0?}
    L -->|Yes| M[return null — chip hidden]
    L -->|No| N[TotalUsageResult with spentTotal]
    N --> O[ChatHeader chip shows spentTotal\nTooltip breaks down context / discarded / title / total]

_{Reviews (3): Last reviewed commit: "Review fixes" | Re-trigger Greptile}

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