[Feature]: Show current session cost on hover of the context meter, for all providers including OpenCode

[n0ah37]

Before submitting

• I searched existing issues and did not find a duplicate.

Area

apps/web (composer context meter), apps/server (usage reporting)

Problem

The context meter next to the composer send button shows context usage, but the session's cost is not shown anywhere live. For OpenCode threads the meter also stays empty when routed through OpenRouter (#8388), and per-session cost is not surfaced for OpenCode or other providers.

Requested behavior

• Keep the live context ring next to the send button and update it after each round.
• Hovering the ring shows the current session's cost, plus used/max context tokens. This matches how OpenCode shows it.
• Works for every provider that reports token usage (OpenCode, Codex, Claude, Cursor, Antigravity), not only Claude and Codex.
• If a model has no price entry, show the token counts and mark the cost as unpriced instead of showing $0.

Related

• [Feature]: Show the context percentage on the meter, not only in its popover #7651 (closed): show the context percentage on the meter, not only in its popover
• [Bug]: OpenCode threads via OpenRouter never show context-window usage in the composer #8388 (open): OpenCode threads via OpenRouter never show context-window usage
• [Bug]: Usage dashboard ignores OpenCode provider sessions, spend shows $0 #11121 (closed, not planned): Usage dashboard shows $0 for OpenCode sessions
• [Bug]: Usage leaves Daybreak models unpriced because Codex and LiteLLM use different aliases #7752 (open): models left unpriced because provider aliases differ

🤖 Generated with Claude Code

[n0ah37]

I have an implementation ready for review: n0ah37#2. Each provider turn carries the provider's own cost estimate (Claude's total_cost_usd split per turn, and OpenCode 1.x and 2.x step costs). The meter's popover sums these as Session cost, and providers that report no cost show Unpriced. It does not price anything from the LiteLLM table. If you approve this scope, I'll open it against this repo.