Silent housekeeping (NO_REPLY)

Apus supports "silent" turns for background tasks where the user should not see intermediate output.

• The assistant starts its output with the exact silent token NO_REPLY / no_reply to mean "do not deliver a reply to the user." Apus strips/suppresses this in the delivery layer.
• Exact silent-token suppression is case-insensitive: NO_REPLY and no_reply both count when the whole payload is just the silent token.
• As of 2026.1.10, Apus also suppresses draft/typing streaming when a partial chunk begins with NO_REPLY, so silent operations do not leak partial output mid-turn.
• This is for true background/no-delivery turns only - it is not a shortcut for ordinary actionable user requests.

Pre-compaction memory flush

Before auto-compaction happens, Apus can run a silent agentic turn that persists durable state through the selected memory provider so compaction cannot erase critical context. Memory Core writes memory/YYYY-MM-DD.md in the agent workspace; other providers can expose their own persistence tools. Apus monitors session context usage, and once it crosses a soft threshold below the compaction threshold, it sends a silent "write memory now" directive using the exact silent token NO_REPLY / no_reply so the user sees nothing.

Memory flushing runs against a private, detached view of the conversation. Its internal prompts and replies never enter the original transcript, including when a new user message interrupts it. Memory-file writes remain durable. Required preflight excludes the already-admitted waiting user; post-reply flushing includes the completed turn. Any compaction inside the flush affects only its private view; the original conversation has a separate compaction step.

Config (agents.defaults.compaction.memoryFlush), full reference at /gateway/config-agents:

The host resolves the reserve, soft margin, transcript-byte guard, and optional model from this config and the active context window before it asks the selected memory provider for flush content and persistence. Providers inherit those values unless they deliberately override an optional timing field in their plan. When enabled is false, the host skips the provider resolver. Without a flush plan, maintenance still uses the effective compaction reserve.

The default 20,000-token reserve is capped at one quarter of the context window. The default 4,000-token soft margin is capped at half the window left after that reserve. For a 32,768-token window, the host therefore uses an 8,192-token reserve and a 4,000-token soft margin. Early flushing starts at 20,576 projected tokens. Blocking token compaction starts at 24,576, or later if an applicable server threshold is higher. Between those thresholds, memory flushing can run without requiring compaction. The transcript-byte guard defaults to 2 MiB and remains independent. Nonpositive thresholds suppress their trigger.

When memory flush refreshes stale usage, it includes projected messages appended after the latest valid provider usage report before saving the total as fresh. The following compaction check therefore accounts for that later transcript growth.

Notes:

• The built-in prompt and system prompt include a NO_REPLY hint to suppress delivery.
• When model is set, the flush turn uses that model without inheriting the active session's fallback chain, so local-only housekeeping does not silently fall back to a paid conversation model on failure.
• The flush runs once per compaction cycle (tracked in the session row).
• The flush runs only for embedded Apus sessions; CLI backends and heartbeat turns skip it.
• Memory Core's file flush is skipped when the session workspace is read-only (workspaceAccess: "ro" or "none"). A tools-arm provider does not require writable workspace access.
• See Memory for the workspace file layout and write patterns.

Apus exposes a session_before_compact hook in the extension API, but the flush logic above lives on the Gateway side (src/messaging/auto-reply/reply/memory-flush-plan.ts, src/messaging/auto-reply/reply/memory-flush.ts, and src/messaging/auto-reply/reply/agent-runner-memory.ts), not on that hook.