feat: daily session reset by timezone

[americodias]

Summary

Adds two settings — SESSION_DAILY_RESET_HOUR (0-23) and SESSION_DAILY_RESET_TIMEZONE (IANA tz string) — that force session expiry at a recurring daily boundary. A session whose last_used falls before today's reset hour (in the configured local timezone) is treated as expired in addition to the existing SESSION_TIMEOUT_HOURS rule.

Why

The existing inactivity-based timeout works well for natural breaks but doesn't enforce a fresh start each day. Some users (myself included) prefer "every morning, the bot starts a fresh session" to avoid yesterday's working set leaking into today's first message — without needing to remember /new.

Two examples:

• Personal/journaling use: each day's first message should be a clean slate. SESSION_DAILY_RESET_HOUR=3 + SESSION_DAILY_RESET_TIMEZONE=Europe/Lisbon ensures the 9am check-in starts fresh even if the previous session was at 11pm.
• Team/operational use: similar reasoning for daily standups, incident handoffs.

What

src/claude/session.py — ClaudeSession.is_expired() gains two optional parameters (daily_reset_hour, daily_reset_tz); existing (timeout_hours) calls remain valid (defaults preserve previous behavior). New SessionManager._is_session_expired(session) helper threads both rules through one call site.

src/claude/facade.py — two existing s.is_expired(self.config.session_timeout_hours) callsites switch to self.session_manager._is_session_expired(s) so they pick up the daily rule.

src/config/settings.py — adds the two new settings:

session_daily_reset_hour: Optional[int] = Field(
    default=None,  # disabled by default
    description="Hour of day (0-23) to force session reset. None = disabled.",
    ge=0, le=23,
)
session_daily_reset_timezone: str = Field(
    default="UTC",
    description="Timezone for daily reset hour (e.g. 'Europe/Lisbon')",
)

How it works

The logic is a lazy expiry check, not a background scheduler:

# (simplified)
now_local = datetime.now(UTC).astimezone(ZoneInfo(daily_reset_tz))
today_reset = now_local.replace(hour=daily_reset_hour, minute=0, second=0)
if now_local < today_reset:
    today_reset -= timedelta(days=1)
last_used_local = _to_utc(session.last_used).astimezone(tz)
if last_used_local < today_reset:
    return True  # expired

So a session created Tuesday 11pm and accessed Wednesday 9am — with reset at 3am Lisbon — is detected as expired the moment Wednesday's is_expired() runs. No timer, no race condition, no jobs to schedule.

Compatibility

• Disabled by default (session_daily_reset_hour = None). Pure no-op when unset.
• All existing is_expired(timeout_hours) callsites keep working — the new params are optional with sensible defaults.

Test plan

• With reset disabled (default), behavior unchanged — sessions only expire on inactivity timeout
• With SESSION_DAILY_RESET_HOUR=3 and TZ=Europe/Lisbon: session created 11pm, query at 9am next day → fresh session
• Cross-DST transitions (zoneinfo handles correctly via ZoneInfo)
• Cross-timezone deployment: bot running in UTC, SESSION_DAILY_RESET_TIMEZONE=America/New_York → reset boundary follows NYC, not UTC

Notes

Uses zoneinfo.ZoneInfo from stdlib (3.9+) — no new dependencies. The codebase already requires Python 3.11.