Composer token-usage tooltip caps the denominator at 128,000 regardless of the model's actual context window

[jeyarajcs]

Before filing

• I searched open and closed issues for duplicates.
• I reproduced this on the latest release.
• This is one bug, not several bundled together.

Closest existing issue

#106 (about defaulting Codex sessions to the 272K pricing boundary) is adjacent — it's about which window Codex sessions should use, while this report is about the composer token meter displaying a wrong window for models whose real context size differs from 128K.

What's broken

The token-usage tooltip on the composer (hover over the progress circle next to the send/stop buttons) always shows a denominator of 128,000 tokens, even when the session's model has a much larger context window. The numerator can also exceed the denominator many times over — in my session it reads 5,145,485 / 128,000 tokens — so the meter conveys no usable information about how full the context actually is.

Steps to reproduce

1. Launch Berd (0.6.2)
2. In the local Claude Code setup, enable the 1M-token context window (the model appears in Berd's picker as Claude Fable 5[1m] / model_id claude-fable-5[1m] on the claude-acp harness). Same applies to a Codex model configured for a 400K window.
3. Create a session with that model and use it for a while (long conversation / many turns)
4. Hover the token-usage indicator at the bottom-right of the composer

What you expected to happen

The denominator should reflect the model's actual context window (1,000,000 for the [1m] Fable model, 400K for the configured Codex model), and the numerator should stay ≤ the denominator if it represents context occupancy. If the numerator is instead cumulative session usage, the two numbers shouldn't be presented as a single used / limit fraction.

Also: if there is a way for users to set/override the context window Berd assumes per model, I couldn't find one — that would be a fine resolution too.

What actually happened

Tooltip shows 5,145,485 / 128,000 tokens. The numerator is ~40× the denominator and the session keeps working fine (the harness itself has the 1M window), so the 128,000 looks like a hardcoded fallback rather than the real limit.

Possibly relevant: berdctl info models --json returns only model_id and name per model — no context-length metadata — so the app plausibly has no way to know the real window for harness-defined models like claude-fable-5[1m] and falls back to a 128K default.

How often does it happen?

Every time — reliably reproducible

Berd version

0.6.2

Operating system

macOS (Apple Silicon)

Model and provider

Claude Fable 5[1m] via the claude-acp (Claude Code) harness / Anthropic; also observed with a Codex model configured for a 400K window

Relevant log output

no relevant log output — grepped ~/Library/Logs/xyz.block.berd/berd.log for token/context/limit lines around the time of observation; nothing matched

Screenshots, recordings, or other context

Screenshot of the tooltip will be attached in a comment below (filed via gh CLI, which can't upload attachments).

[jeyarajcs]