A steering message confirmed to the user as injected:true could still be
lost: after the loop's last HasPending check it runs out and the chain
finalizes (done event + final messages still streaming — the "few extra
messages" the user sees), then the finally block called Clear() and threw
the queue away. A message arriving in that window was accepted
(IsStreaming still true, Stop runs only in finally) but never drained and
never persisted, so it vanished after F5. Platform-independent; Windows
only widened the window via slower CLI teardown.
Replace the queue with a per-session gated state: Open() at chain start,
Close() at chain end. TryEnqueue() and Close() are mutually exclusive via
a per-session lock, so a confirmed injection can no longer be lost — the
loop either drains it or Close() returns it as leftover. The endpoint now
opens the gate at chain start, uses TryEnqueue as the authoritative check
(false → client resends as a normal message), and in finally closes the
gate and persists any leftover as Type="steer" instead of discarding it,
so it survives F5 and the model sees it on the next message.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Let the user inject a message into a running chain instead of only being
able to abort it. While a chain streams, typing + Enter sends the text to
a new /api/chat/steer endpoint; it is drained at the next iteration
boundary, wrapped with a hint so the model actively classifies it
("complements the task -> keep working" vs. "changes course -> adjust"),
and stored as a Type="steer" user message so it survives reload.
Shared infrastructure (provider-agnostic):
- SteeringQueue: out-of-band queue keyed by sessionId, mirrored from
StreamingTracker (Enqueue/Drain/Clear).
- Program.cs registers it as a singleton and passes it to AnthropicService.
- ChatEndpoint: POST /api/chat/steer enqueues only while IsStreaming,
Clear() in the finally.
- ChatService.BuildHistoryFromDb groups Type="steer" so no two
consecutive user turns are produced on re-chat.
- Frontend api.js/chat.js/bubbles.js/history.js + chat.css render the
optimistic steer bubble and the steer_injected SSE event; Enter during
a stream sends a steer instead of being blocked.
Anthropic API path:
- Drain point B (tool boundary, merged into the tool_result user turn)
and C (turn end -> inject + continue instead of finalize).
Claude CLI path (kill-and-restart):
- The agentic loop runs inside the claude child, so true mid-turn inject
is impossible. On a pending steer the child is killed at the next tool
boundary, progress is rebuilt from the DB as a <work_in_progress>
transcript, and the CLI is restarted with the steer appended.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
