Show an upper-bound estimate of API-equivalent cost in the thread header

[pantharshit007]

Feature request

Show a conservative, upper-bound estimate of the current conversation's API-equivalent cost directly in the thread header, with an expandable cost breakdown.

Why this would be useful

After an eight-hour conversation, I would like to quickly see something like: “This conversation is estimated to have cost $X in API usage at standard rates.” This would help me understand the value and scale of the usage, even when access is subsidised or included in a subscription rather than billed per API call.

The figure should represent estimated API-equivalent usage cost, clearly distinguished from what I actually paid.

Proposed UI

• Add a compact estimated-cost indicator in the top-right of the current thread's header, just before Add action (for example, Est. $4.81).
• Update the estimate as the conversation progresses and retain the cumulative total for the thread.
• Clicking the indicator opens a popover with a breakdown by model/provider, the current thread subtotal, associated agent or PR-review usage where attributable, and the total. Avoid double-counting subtotals and related work.
• Include a short explanation of how the estimate was calculated and what it includes.

Estimation behaviour

Use recorded token usage and the applicable model's standard API pricing wherever available. Account for input, output, and cached tokens when that information is available, including model changes within a conversation.

Where pricing or cache details are uncertain, use conservative assumptions and explain them. The goal is an upper-bound estimate where the available data supports one; if incomplete usage data prevents a reliable upper bound, clearly label the figure as a partial estimate rather than presenting it as a guaranteed maximum. Unknown prices or missing usage should not silently appear as zero cost.

This is intended as an informational estimate of what the conversation would have cost at standard API rates without subsidies or subscription coverage, not an invoice or a spending cap.

[juliusmarminge]

Note

Grok responding on behalf of Julius.

Duplicate of #13073 — same request for per-thread estimated API-equivalent cost (input/output/cached tokens, model breakdown, distinguished from billed/subscription spend). Header/Est. $… placement is a UI detail that belongs on that thread.

Please +1 / fold any extra detail into #13073. Related prior work (closed unmerged): #9016 (Usage page thread breakdown; previously attributed to #13073), #9017 (composer thread cost indicator), #9136. Broader usage/quota visibility: #6683 / closed #228. Near-miss left open: #14404 (context-window usage, not cost).