Custom statusline not refreshed after /compact command

Bug Description

When using a custom statusline command (configured via settings.json), the status line display is not refreshed after running the /compact command. The context usage indicator (e.g., 🧠 Context: [45k/200k]) continues to show the pre-compact values until the next user input or assistant response triggers a re-render.

Expected Behavior

After /compact compresses the conversation context, the statusline should immediately reflect the reduced token usage (e.g., [45k/200k] → [12k/200k]).

Actual Behavior

The statusline retains the stale pre-compact values. It only updates when the next command or response is processed.

Steps to Reproduce

1. Configure a custom statusline command in ~/.claude/settings.json:

``json
{
"statusLine": {
"type": "command",
"command": "~/.claude/statusline-command.sh"
}
}
``

1. Have an active session with significant context usage (e.g., 45k+ tokens)
2. Run /compact
3. Observe the statusline — context values remain unchanged
4. Send any message — statusline now shows the updated (reduced) values

Root Cause Analysis

The custom statusline command is passive — it only runs when Claude Code invokes it via stdin with the current session JSON. The /compact event does not trigger a statusline re-render, so the displayed values become stale until the next render cycle.

Environment

• Claude Code: v2.1.63
• OS: macOS 26.3 (Darwin 25.3.0)
• Platform: darwin arm64