Control UI: subagent context badge can display historical total tokens as current context usage

Summary

The Control UI subagent/session badge can show impossible values such as:

• 100% context used 468.2k / 48k

This appears to be a UI/display bug, not a real live-context overflow.

Why this matters

The badge label implies current context pressure, but the displayed numerator can come from accumulated historical message.usage.totalTokens while the denominator comes from current contextTokens.

That creates a misleading state where:

• operators may think a live subagent is far beyond its context window,
• users may misdiagnose failures as context exhaustion,
• historical token/cost totals get misread as active context usage.

Observed behavior

In a real subagent thread, the UI displayed:

• 100% context used 468.2k / 48k

However:

• live active context was only in the tens of thousands of tokens,
• 468.2k matched historical accumulated message.usage.totalTokens,
• 48k matched the session context window,
• the label still said context used.

Suspected root cause

The UI appears to mix two different concepts:

• totalTokens: historical/accumulated usage
• contextTokens: current context window usage/capacity display

Additionally, the freshness gate was too permissive:

if (e?.totalTokensFresh === !1) return u;

This means the badge was hidden only when freshness was explicitly false, but could still render when freshness was unknown/stale rather than strictly confirmed.

Local mitigation tested

A local bundled-asset patch changed the guard to require explicit freshness:

if (e?.totalTokensFresh !== !0) return u;

After that change, stale/unknown totals no longer rendered as current context usage.

Expected behavior

One of these should happen:

1. The context used badge should render only from current context-specific metrics.
2. If the numerator is historical total usage, the label should clearly say total/historical usage rather than context used.
3. If freshness is not explicitly confirmed, the badge should not present the value as live current context.

Minimal reproduction idea

1. Run a subagent/thread long enough to accumulate large historical token totals across many messages.
2. Reopen or inspect the session in Control UI.
3. Observe whether the badge shows a very large numerator under context used, potentially larger than the configured context window.

Impact

• misleading operator telemetry
• false diagnosis of context-window exhaustion
• confusion between live context pressure and cumulative token spend/history

Notes

This was observed and locally documented on 2026-04-02. A local workaround was applied only at the bundled asset level, so a source-level fix would still be preferable.