[BUG] Context window indicator shows 94% on fresh session — breakdown sums to ~17%

Summary

On the Claude Code Desktop app, the context-window indicator in the bottom-right shows a percentage that contradicts its own breakdown. Fresh session, one short message: indicator says 187.9k / 200.0k (94%) but the breakdown panel lists Free space: 166.0k (83%) and the line items sum to ~34k used.

Environment

• App: Claude Code Desktop 1.11187.4
• OS: macOS 26.5
• Model: Claude Opus 4.7 (Extra tier)
• Context cap shown in indicator: 200K

Steps to reproduce

1. Quit Claude Desktop completely.
2. Re-launch.
3. Click + New session.
4. Send a single short message (e.g. "new session test").
5. Click the context-window indicator in the bottom-right to expand the breakdown.

Expected behaviour

The percentage in the indicator header should match the sum of the line items, or at least equal (total - free space) / total.

Actual behaviour

Indicator header: Context window 187.9k / 200.0k (94%)

Breakdown line items:

| Component | Size | % |
|---|---|---|
| Memory files | 16.8k | 8.4% |
| Skills | 6.5k | 3.3% |
| System prompt | 6.0k | 3.0% |
| Custom agents | 3.0k | 1.5% |
| Messages | 1.8k | 0.9% |
| Free space | 166.0k | 83.0% |
| MCP tools | 0 (227 tools) | — |

Sum of used line items = 34.1k → real usage is ~17%, not 94%.

Internal contradiction

The same panel shows both (94%) in the header and 83.0% Free space — these can't both be right. Free space should equal 100% - used%, so the header's 94% would imply 6% free, not 83%.

Why this matters

A user seeing 94% will believe context is nearly full and start trimming workspace memory / disabling plugins / restarting sessions to reclaim space that was never used. Real fresh-session baseline is ~34K (lean), but the indicator suggests the user is one message away from auto-compaction.

In my case I disabled 13 plugins and removed 4 custom agents chasing a phantom problem before noticing the breakdown contradicted the header.

Possibly related

• #64546 (closed dup) — "stale Messages count from previous session on new session start" — sounds like a sibling symptom.
• #63015 (open) — statusline reporting 100% context used but behavior doesn't match.
• #62063 (closed dup) — defaults to 1M context on fresh session — display-tier confusion.

The breakdown line items appear correct; the percentage in the header is the bug.