Streaming Runtime

Current path

ChatService frames the turn. ServiceStreamingRuntime calls
StreamingChatExecutor.run_unified(), which drives the single
AgenticLoop.run_streaming() path through StreamingActAdapter.

The deprecated run() alias, AgenticLoop.stream_chat() wrapper and
_stream_chat_impl path are removed.

Turn flow

---
title: Current streaming turn
---
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sequenceDiagram
  actor Client
  participant Chat as ChatService
  participant Frame as ChatTurnRuntime
  participant Runtime as ServiceStreamingRuntime
  participant Exec as StreamingChatExecutor
  participant AL as AgenticLoop
  participant Act as StreamingActAdapter
  Client->>Chat: stream_chat(message)
  Chat->>Frame: enter + start task report
  Chat->>Runtime: stream(message)
  Runtime->>Exec: run_unified(message)
  Exec->>AL: run_streaming(message)
  loop PERCEIVE · PLAN · ACT · EVALUATE · DECIDE
    AL->>Act: stream_turn_act(...)
    Act->>Exec: execute_turn_streaming(...)
    Exec-->>Act: chunks + turn result
    Act-->>AL: chunks + outcome
    AL-->>Exec: stream chunks
    Exec-->>Runtime: stream chunks
    Runtime-->>Chat: stream chunks
    Chat-->>Client: stream chunks
  end
  Runtime->>Exec: close nested generator
  Runtime-->>Chat: stream ends
  Chat->>Frame: finish task report
  Chat->>Frame: exit turn scope
  Chat->>Chat: release turn lock

Capability map

The stream cluster receives an enumerated ChatRuntimeServices view. Related operations share
one capability so callers do not accumulate facade fields.

Capability	Owns	Failure behavior
Session requirements	Required files, outputs and read state	Live session owner
Delivery	Request and response delivery	Existing delivery contract
Planning	Task preparation, goals, intent, guidance and tool selection	Required wiring fails early
Governance	Request/response policy	Invalid configured result fails closed
Completion	High-confidence completion and clean summary	Optional when disabled
Conversation	System-prompt insertion, history, actual usage and terminal summary persistence	Startup fails closed; later accounting is best effort; weak owner
Tool calls	Reset, parse and validate	Missing runtime fails closed
Stream lifecycle	Start, context binding, cancellation, retry timing and cleanup	Required; weak live owner
Stream metrics	Initialization, first-token timing, cost and terminal diagnostics	Required; weak live owner
Task state	Reset, classification, continuation and prompt-derived budgets	Required; weak live owner
Context lifecycle	Background compaction startup	Optional; weak live owner
Runtime intelligence	Request guidance, learned routing and outcome feedback	Optional; weak live owner
Recovery	Retry and fallback coordination	Existing recovery contract

Limit ownership

AgenticLoop.run_streaming enforces the active iteration bound; StreamingActAdapter syncs
the turn counter and StreamingChatExecutor checks cancellation around provider/tool work.
The bound ChatService context-limit handler remains a compatibility API and is not
rediscovered from the stream cluster.

Lifecycle invariants

Required invariants

• Close nested async generators before releasing the shared turn lock.
• Finish task reports on success, error and cancellation.
• Check cancellation around provider and tool boundaries; preserve accounting for completed
  in-flight tools, then close the loop before emitting the terminal cancellation signal.
• Resolve mutable session and controller state from its current owner.
• Keep configured governance gates through bootstrap; malformed results are errors.
• Update session totals through the metrics capability before finalizing cost and reports.
• Publish bounded resume context through task state, including on error and stream close.
• Start configured background compaction once during stream preparation.

Guard	What it prevents
Stream-turn AST caps	New access to migrated orchestrator internals
Facade and hotspot caps	Growth in the composition facade
Run/stream parity	Divergence between buffered and streaming semantics
Lifetime regressions	Lock, generator or report leaks after cancellation
Usage regressions	Double counting or loss during reset/restore

Ownership status

---
title: FEP-0031 ownership progress
---
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flowchart LR
  subgraph DONE["Implemented"]
    T["Turn frame"]
    P["Planning and guidance"]
    E["Stream execution controls"]
    L["Stream lifecycle"]
    X["Stream metrics and session totals"]
    K["Task classification and resume context"]
    C["Context lifecycle"]
    I["Runtime intelligence"]
  end
  subgraph NEXT["Remaining"]
    S["Provider and broader runtime state"]
    F["Handler factories"]
    M["Facade shims and mixins"]
  end
  T --> S
  P --> S
  E --> S
  L --> S
  X --> S
  K --> S
  C --> S
  I --> S
  S --> F --> M

FEP-0031 remains Draft / in progress. See the
proposal and measured progress
and the canonical architecture.

Compatibility

Public Agent.run(), Agent.stream() and facade chat methods retain their contracts.
Compatibility coordinators forward to the service/runtime path; they do not own a second
streaming engine.