Long working sessions auto-archive mid-conversation; no opt-out

Symptom

In an active Claude Code session — specifically the chat UI (claude.ai/code in a browser, or possibly the desktop app — see env note below) — the input field gets replaced with a notice that reads "this conversation has been archived" and an "Unarchive to continue chat" button. This happens automatically without any user action, apparently after some inactivity threshold.

The conversation is recoverable via the Unarchive button (so no data is lost), but for long working sessions that include multi-step plans, sub-agents in progress, MCP tool state, and verification cycles, having the input field disappear mid-flow is disruptive. The "Unarchive" prompt also makes it look like the model has stopped responding, when really the user just needs to click through.

What I tried (and what didn't fix it)

Setting cleanupPeriodDays: 999999 in %USERPROFILE%\.claude\settings.json does not prevent this — that setting controls local transcript file cleanup at startup, not the in-chat archive behavior.

What I'm looking for

Either:

• A user-facing setting (e.g. disableAutoArchive: true in settings.json, or a per-conversation "pin" / "keep active" toggle in the UI), OR
• Documentation explaining the threshold so we can plan around it

Why this matters for working sessions

For typical short Q&A chats the auto-archive is probably fine — it keeps the active list manageable. But Claude Code working sessions routinely run 1–4 hours and include:

• Background agents that I'm waiting on
• Multi-step plans where I step away to take an action (apply a migration, click through a dashboard, run a manual test) and come back
• MCP tool state I don't want to interrupt

When the chat archives during that gap, it breaks the flow and forces an extra click that can fire on top of an in-progress response.

Environment

• Platform: Windows 11
• Claude Code: confirmed running but couldn't determine version via claude --version, npm globals, registry, or %LOCALAPPDATA%\Programs — suggests browser-based use of claude.ai/code (or a non-standard install path)
• Symptom occurs across multiple long-running sessions

Workaround for now

Click "Unarchive" whenever it appears. That works but isn't viable for sessions where the user wants to leave Claude Code running unattended (e.g., during a long background agent or a multi-hour build).

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Thanks for considering. Happy to provide more detail or test a proposed fix.