What causes "Failed to steer turn: {error}" in Hmbown/CodeWhale?

Retry the steer; if the turn truly finished, send a normal new message instead.

Failed to steer turn

Error message

Failed to steer turn: {error}

What it means

Raised when `engine.reserve_steer()` fails while attempting to steer (inject a mid-turn user message into) an active turn. The engine's steer mailbox could not reserve a slot — typically because the turn is no longer accepting steers (finishing/stopping) or the engine's operation channel is saturated or closed. The underlying engine error is interpolated into the message.

Solutions

Retry the steer; if the turn truly finished, send a normal new message instead.
Check whether the turn was interrupted or completed concurrently (`Turn is stopping and cannot be steered` guards run first).
If the engine channel is closed, reload the thread (ensure the engine is re-spawned) and retry.

Defensive patterns

Strategy: fallback

Try / catch

if let Err(e) = runtime.steer_turn(&thread_id, &turn_id, text).await {
    // fall back to sending a new message on the thread
}

Prevention

Steer early in the turn rather than right as it finishes.
Check turn status before steering; do not steer interrupted/stopping turns.
Avoid steering while a config reload or engine swap is in progress.
Treat a steer failure as a signal to check whether the turn already completed.

When it happens

Trigger: Calling the steer API (`steer_turn`) on a running turn when `reserve_steer()` returns Err — e.g. the active turn just reached its terminal phase, an interrupt was requested concurrently, or the engine op channel is closed/full.

Common situations: User sends a steer message at the same moment the model finishes its turn; steering a turn that another window just interrupted; racing an engine reload (the channel changed between locks).

Understand the failure class

Background: "Invalid state transition" errors: "status must be X, actually Y", "already rejected/charging/uninstalled", "cannot ... while running" — what they mean when a library rejects your call — this error's family across 31 libraries.

Related errors

AI-assisted analysis of Hmbown/CodeWhale@73e0f67d83 (2026-09-22). Data as JSON: /api/errors/364a3f0f8ea5d1eb. Report an issue: GitHub.

Appendix: source

Thrown at crates/tui/src/runtime_threads.rs:10412

                let Some(active_turn) = active_thread.active_turn.as_mut() else {
                    bail!("No active turn on thread {thread_id}");
                };
                if active_turn.turn_id != turn_id {
                    bail!("Turn {turn_id} is not active on thread {thread_id}");
                }
                if active_turn.interrupt_requested {
                    bail!("Turn {turn_id} is stopping and cannot be steered");
                }
                active_thread.engine.clone()
            };
            touch_lru(&mut active.lru, thread_id);
            engine
        };

        let permit = engine
            .reserve_steer()
            .await
            .map_err(|error| anyhow!("Failed to steer turn: {error}"))?;

        let now = Utc::now();
        let queued_turn;
        let item = TurnItemRecord {
            schema_version: CURRENT_RUNTIME_SCHEMA_VERSION,
            id: format!("item_{}", &Uuid::new_v4().to_string()[..8]),
            turn_id: turn_id.to_string(),
            kind: TurnItemKind::UserMessage,
            // Queued, not Completed: the text is in the engine's mailbox, not
            // yet in the turn's record. `spawn_steer_settlement` flips it once
            // the engine reports what actually happened (#6276).
            status: TurnItemLifecycleStatus::Queued,
            summary: summarize_text(&prompt, SUMMARY_LIMIT),
            detail: Some(prompt.clone()),
            metadata: None,
            artifact_refs: Vec::new(),
            started_at: Some(now),
            ended_at: None,

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