When many background tasks complete in rapid succession while the parent
session is idle, each completion fired its own promptAsync call, stacking
N consecutive `<system-reminder>` user messages with no assistant turn
between. Hyperplan + many parallel explore subagents made this very
visible to the user.
Route the idle-path through the existing pendingParentWakes queue with a
100ms debounce window. Notifications arriving during the debounce join
the same batch, the 150ms settle window also coalesces newcomers, and a
single batched prompt fires to the parent. Busy-path semantics are
unchanged (still 1s retry).
Prior attempts (1c05c60dc, ea55c385b, a337635e3) all coalesced only the
busy-defer path, leaving the idle-immediate-send path uncoalesced.
Rename BackgroundTask and attempt ID fields to camelCase across background-agent consumers while moving BackgroundManager construction to a single config object.
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>
H3: cancelTask(skipNotification=true) now schedules task removal.
Previously the early return path skipped cleanup, leaking task objects
in this.tasks Map permanently. Extracted scheduleTaskRemoval() helper
called from both skipNotification and normal paths.
H2: Per-task completion cleanup timer decoupled from allComplete check.
Previously cleanup timer only ran when ALL sibling tasks completed. Now
each finished task gets its own removal timer regardless of siblings.
H1+C2: TaskHistory.clearAll() added and wired into shutdown(). Added
clearSession() calls on session error/deletion and prune cycles.
taskHistory was the only data structure missed by shutdown().
Tests: 10 pass (3 cancel + 3 completion + 4 history)
YeonGyu-Kim