feat: session TTL + turn limit to prevent O(N²) token growth

[oct26th]

Problem

Every message resumes the full conversation history, causing token usage to grow O(N²) with turn count. There's currently no mechanism to bound session lifetime or notify users of context usage.

Proposed solution

1. Session TTL — auto-clear session after N hours of idle (env: SESSION_TTL_HOURS, default 24, 0 = disable)
2. Turn limit — auto-clear session after N turns (env: SESSION_MAX_TURNS, default 50, 0 = disable)
3. /usage command — show session age, idle time, turn count, and cumulative cost

DB: two new columns (turn_count, total_cost_usd) added via migration — fully backwards compatible.

I've implemented this in my fork: https://github.com/oct26th/claudecode-discord — happy to open a PR if there's interest.

[chadingTV]

Thanks for the thoughtful proposal and for implementing it in your fork!

We've been thinking about usage visibility too, and just shipped /usage in v1.2.0 — it shows Claude Code usage (Session 5hr / Weekly 7day / Sonnet 7day) directly in Discord, plus a usage dashboard in the tray control panel on all 3 OS.

Regarding the session TTL and turn limit:

• We're cautious about auto-clearing sessions — unexpected context loss can be a worse UX than high token usage, especially for long-running tasks. Claude Agent SDK also handles context window management internally to some extent.
• Currently users can manage sessions manually via /sessions (resume/delete) and /clear-sessions, which gives them full control over when to start fresh.

That said, we'd be open to a warning/notification approach (e.g. "this session has N turns, consider starting a new one") rather than auto-clearing. If you'd like to adapt your PR in that direction, we'd be happy to review it!

The turn_count and total_cost_usd tracking in your fork is interesting — if you'd like to submit just the tracking + display part (without auto-clear), that could be a nice addition to /status or /sessions.

Thanks again for the contribution!

[oct26th]

Thanks for the thoughtful feedback!

Just to clarify the auto-clear behavior: both SESSION_TTL_HOURS and SESSION_MAX_TURNS default to opt-out-friendly values and can each be set to 0 to disable entirely. Operators who prefer fully manual session control can set both to 0 with no functional change. The goal was to give a safe default that prevents unbounded O(N²) token growth without forcing anything on users who don't want it.

That said, your point about unexpected context loss is well taken — even with configurable defaults, users might not realize a clear is coming. I'm happy to add a warning notification before any auto-clear triggers (e.g., "⚠️ Session will be cleared in 5 minutes due to idle TTL — use /clear-sessions to do it now, or send a message to reset the timer").

As for /usage — the implementation in this PR also surfaces turn_count and total_cost_usd alongside session age and idle time, which might be a bit more detailed than what's currently in v1.2.0. Happy to align with whatever format you prefer.

Would you be open to reviewing the PR with the warning notification added on top? Happy to iterate.