[dbezverkhnii]

The core wants to close idle IMAP connections quickly in the background and keep them warm on screen, by switching automaticDisconnectDelay when the app changes mode (COR-246). That knob could not be turned at runtime: the session copied it into a connection once, at creation, in whole seconds, and Swift did not expose it.

• A connection reads the delay from its session when it arms the idle timer, instead of keeping a copy.
• The setter is callable from any thread. It restarts every idle timer already running, on the session's dispatch queue, where the pool and the timers live.
• The delay is a double in C++ and the C API; MCOIMAPSession.automaticDisconnectDelay: TimeInterval in Swift.

The C++ changed, so the Windows prebuilt needs a rebuild for this revision before a tag.

Tests: IMAPAutomaticDisconnectDelayTests. A running timer restarts with a shorter delay, sub-second delays are kept, a command in flight is not cut, a leased connection waits for its release, and concurrent changes settle on the last one. Each one was checked to fail without the matching part of the fix.

🤖 Generated with Claude Code

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Note

Medium Risk
Changes IMAP connection lifecycle timing and cross-thread pool updates; incorrect timer restarts could drop idle sockets early or keep them open longer than intended.

Overview
IMAP idle auto-disconnect delay can now be changed at runtime so apps can tighten disconnects in the background and keep connections warm on screen.

Session-owned delay: Connections no longer store their own copy at creation. When the idle timer is armed, they read IMAPAsyncSession::automaticDisconnectDelay(). setAutomaticDisconnectDelay is thread-safe (lock + hop to the session dispatch queue) and walks the pool to restartAutomaticDisconnect on any connection that already has a timer running.

API: Delay type moves from time_t (whole seconds) to double through C++/C bindings; Swift adds automaticDisconnectDelay: TimeInterval on IMAPSession. Per-connection setAutomaticDisconnectDelay is removed in favor of restartAutomaticDisconnect (dispatch-queue only).

Tests: IMAPAutomaticDisconnectDelayTests covers shorter delay restarting an armed timer, sub-second values, in-flight commands not being cut, leased connections waiting for release, and concurrent updates settling on the last value.

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[dbezverkhnii]

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