VS Code extension: Effort slider disappears (instead of disabling) when usage limit forces model fallback

Environment

• Claude Code VS Code extension (native extension UI)
• Windows 11
• Plan with usage limits (effort-capable model + fallback)

Describe the bug

When I hit my usage limit and Claude Code falls back to a model that doesn't support effort control, the Effort slider in the Modes menu disappears entirely rather than rendering in a disabled state.

There is no indication of why it's gone — no greyed-out control, no tooltip, no "unavailable until your limit resets" message. From the user's side it looks like the feature was removed, and it's not obvious that the limit/model-fallback is the cause.

Steps to reproduce

1. Use a model that supports the Effort setting (Effort row visible in the Modes menu).
2. Hit the usage limit so the session falls back to a model without effort support.
3. Open the Modes menu (shift+tab picker).
4. The "Effort (Low/Medium/...)" row is gone entirely.

Expected behavior

The Effort row should stay visible but disabled, with a short reason (e.g. "Effort unavailable — current model doesn't support it / usage limit reached"). A silently vanishing control fails least-surprise: my first instinct was to restart VS Code, which appears to "fix" it only because the limit window resets or the extension re-resolves the model on startup.

Additional context

• After the limit resets, the slider doesn't always come back on its own within the same session — a new chat or Developer: Reload Window is needed, which suggests the limit state is also going stale in the UI.
• /bug is not available in this environment, hence filing here.