When a stream errors out before producing any user-visible content
(text, thinking, or tool calls), the engine now transparently retries
on the next-best arm instead of bubbling the error to the TUI. Covers
the case from the post-SLM screenshot: subprocess CLI agents that
exit non-zero on auth/config failures, network drops mid-stream,
rate-limited arms whose error surfaces after Stream() already returned.
Mechanism: the stream-create + consume blocks are wrapped in a labeled
streamLoop. On s.Err() != nil with empty accumulator, the engine emits
a new EventFailover ("↻ <failed_arm> failed (<reason>) — retrying on
another arm"), excludes the failed arm via task.ExcludedArms, and
re-enters the loop. Cap of 4 failovers per round.
Guards:
- !acc.HasContent() — if text/tool calls already streamed, fail loud
rather than duplicate visible output on retry.
- isFailoverable(err) — deny-list approach: context.Canceled/Deadline
and HTTP 400/413 are fatal; everything else (auth, rate limit, 5xx,
subprocess exit, network) is failoverable.
- Router.ForcedArm() == "" — when the user pinned an arm via --provider,
failover is disabled by design.
- failoverAttempt < maxFailovers — bounded retry budget.
TUI renders EventFailover under the existing "cost" role styling.
shortFailReason strips the subprocess wrapper envelope so the user sees
"Invalid API key. Try again." instead of
"subprocess: exit status 1: Error: Invalid API key. Try again.".
Tests cover the classifier (isFailoverable, shortFailReason), end-to-end
auth-error failover, content-already-streamed guard, and context-cancel
guard. Deterministic across 10x -race runs by giving the failing arm
IsCLIAgent=true to anchor it in tier 0 ahead of the API-tier backup.
The TUI gave no indication that an SLM was configured or active.
You'd see the primary provider on the status line and nothing else,
even with [slm].enabled=true and a successfully booted backend.
Two surfaces added:
1. Status-bar SLM badge. The left side of the status line gains a
dim " · slm: <model> ⚙" suffix when the backend booted, " · slm: ✗"
when it failed, and nothing when SLM is disabled. The ⚙ marker
indicates the model advertises tool support.
2. Per-turn classifier visibility. The existing routing event already
produced "routed → <arm> (task: <type>)" lines in the chat history;
it now also reports which classifier made the decision, e.g.
"routed → ollama/ministral-3:3b (task: explain, by: slm_fallback)".
Lets you tell in real time whether the SLM is actually classifying
or falling back to the keyword heuristic.
Plumbing:
- new tui.SLMInfo struct on tui.Config
- main.go populates it after StartBackend returns
- stream.Event gains RoutingClassifier; engine.runLoop fills it from
task.ClassifierSource on the first round
- Split app.go (2091→1378 lines) into rendering.go, events.go, init.go
- Add EventRouting stream event for router arm transparency
- Add session auto-naming from first user message
- Add context window progress bar in status bar
- Add /keys cheatsheet, /replay for resumed sessions
- Add inline cost-per-turn after assistant responses
- Add diff previews in fs.write/fs.edit permission prompts
- Collapse tool output to 3 lines by default (ctrl+o expands)
- Use AddPrefix for system context instead of InjectMessage
- Handle ContentThinking and ContentToolResult in session resume
- Show session title in resume picker
- Add /model numeric selection snapshot safety
vikingowl