Request Lifecycle

What happens between “user sends a message” and “agent replies”: the full path, with streaming, tool calls, and security gates annotated.

Inbound

flowchart LR
    A[External event] -->|webhook / push / poll / WS| B[Channel adapter]
    B -->|decode, dedup, pair-check| C[Inbound envelope]
    C -->|workspace binding| D[Runtime: process_message]

A channel adapter (e.g. discord.rs, telegram.rs, email_channel.rs) receives platform-native events and converts them into a uniform inbound envelope. The adapter handles:

• Decoding: platform-specific payload → canonical message format
• Deduplication: prevents replaying the same message twice (restarts, retries)
• Pair-check: enforces the [channels.<name>.allowed_users] / IAM policy before the event reaches the runtime

If the channel is not paired or the user isn’t allowed, the event is dropped before the runtime sees it.

Agent loop

sequenceDiagram
    participant CH as Channel
    participant RT as Runtime
    participant SEC as Security
    participant MEM as Memory / history
    participant PR as Provider
    participant TL as Tool

    CH->>RT: process_message(envelope)
    Note over RT: resolve memory-inject policy from the turn's TurnOrigin
    RT->>MEM: recall(query, session scopes)
    MEM-->>RT: entries
    Note over RT: render [Memory context] preamble (engine-side)
    RT->>PR: chat(system, history, tools)
    loop Streaming
        PR-->>RT: StreamEvent::TextDelta
        RT-->>CH: draft update (if channel supports it)
    end
    PR-->>RT: StreamEvent::ToolCall(args)
    RT->>SEC: evaluate_tool_access(name, args, risk)
    alt Blocked
        SEC-->>RT: Err(reason)
        RT->>PR: chat(..., + tool_error)
    else Approval required
        SEC->>CH: ask_operator(prompt)
        CH-->>SEC: approved / denied
    else Allowed
        SEC-->>RT: Ok
    end
    RT->>TL: invoke(args)
    TL-->>RT: ToolResult
    RT->>MEM: append to turn/session history
    RT->>PR: chat(..., + tool_result)
    PR-->>RT: StreamEvent::TextDelta (final)
    RT-->>CH: reply(final)
    RT->>MEM: persist conversation/session history

Key properties:

• Streaming is end-to-end. The provider streams tokens. If the channel adapter reports supports_draft_updates(), the runtime edits a sent message in place as text arrives. Discord, Slack, and Telegram support this.
• Tool calls are mid-stream. The model can emit a tool call while still generating text. The runtime pauses the stream, validates, invokes, feeds the result back, and resumes.
• Security gates every tool call. evaluate_tool_access consults the autonomy level, allow/deny lists, and path boundaries. Medium-risk calls under Supervised autonomy go to the operator-approval path.
• Memory context is engine-injected. Before the first provider call, the turn engine resolves an injection policy from the turn’s TurnOrigin (who initiated the turn): nested sub-turns never inject, scheduled origins (cron, daemon) inject with conversation-category entries excluded, and user-facing origins inject (excluding conversation entries when the turn has no session scope). A spawn site can suppress injection for any origin (for example a cron job with uses_memory = false), and turns that carry no memory backend skip it entirely. A single renderer applies time decay, relevance filtering, a prompt-poisoning skip set, and budget caps uniformly on every path; memory backends only answer recall, they do not format context.
• History and memory are separate. Session history preserves conversation, tool-call, and tool-result continuity. Explicit memory writes persist selected entries in the memory backend. Receipts ride in-band in the conversation text rather than as a separate persisted artifact. For payload ownership details, see Memory and payload lifecycle.

Tool receipts

Successful tool executions can receive an HMAC-SHA256 receipt that is appended to the tool-result text and passed back to the model in the conversation, proving the signed result came from the runtime. The HMAC is keyed by an ephemeral in-memory key and computed over tool_name || args || result || timestamp. Receipts are not written to a separate on-disk log and are not chained; the model can echo them but cannot forge a new valid one without the key. See Tool receipts.

Outbound

Outbound messages go back through the same channel adapter. Adapters with multi-message support (Discord, Slack) can stream long replies as a sequence of messages; others (email, SMS) flush on stream completion.

Where it lives in code

• Agent loop: crates/zeroclaw-runtime/src/agent/turn/ (run_tool_call_loop), with entry points in crates/zeroclaw-runtime/src/agent/loop_.rs (process_message, run)
• Memory-context injection: crates/zeroclaw-runtime/src/agent/memory_inject.rs (resolve_inject_policy, render_memory_context), keyed on TurnOrigin from zeroclaw-api’s ingress types and invoked by the turn engine
• Tool-call access checks: crates/zeroclaw-runtime/src/security/ (iam_policy.rs evaluate_tool_access)
• Channel orchestration: crates/zeroclaw-channels/src/orchestrator/
• Provider streaming: crates/zeroclaw-api/src/model_provider.rs (StreamEvent enum, re-exported from zeroclaw-providers), compatible.rs (SSE parser)

Since #7415, every transport (channels, CLI, cron, gateway WebSocket, RPC/zerocode, ACP, and the embedded Agent API) runs the same turn engine: run_tool_call_loop in crates/zeroclaw-runtime/src/agent/turn/. The streaming and embedded entry points are thin wrappers in agent.rs that set per-caller knobs (dedup, iteration-cap behavior, event emission) around the shared loop. The turn/ module is one file per step: