* feat(subagents): persist and display subagent step history (#3779)
Capture both assistant turns and tool outputs during subagent execution,
stream them in task_running events, and persist them as subagent.* run
events so the subtask card's step timeline survives a reload.
Backend:
- step_events.py: pure layer (capture_step_message, build_subagent_step,
subagent_run_event) shared by streaming and persistence
- executor.py: capture ToolMessage outputs, not just AIMessage turns
- worker.py: persist task_* custom events to RunEventStore (category
"subagent" keeps them out of the thread feed; list_events backfills)
Frontend:
- core/tasks/steps.ts + api.ts: SubtaskStep model, messageToStep,
eventsToSteps, mergeSteps, fetchSubtaskSteps
- subtask card accumulates live steps and backfills on expand
- carry run_id onto history content messages for the events endpoint
* fix(subagents): show AI turns in subtask card + paginate step backfill (#3779)
Two follow-ups to the subagent step-history feature:
Problem 1 — reload backfill could silently truncate the step timeline because
list_events capped at 500 events (seq-ASC) across the whole run. Add task_id
filtering + an after_seq forward cursor to list_events (all three stores +
abstract base + the /events route), and make fetchSubtaskSteps page through one
task's subagent.step events until a short page. No schema migration: the DB
filter rides the existing run-scoped index via event_metadata["task_id"].
Problem 2 — the card only rendered tool steps, so persisted AI turns were never
shown. Replace toolStepsForDisplay with stepsForDisplay: interleave AI reasoning
turns (with text) and tool steps by message_index, drop blank-text AI turns, and
drop the trailing final-answer AI turn when completed (already shown as result).
Card renders AI steps as muted clamped markdown with a sparkles icon.
Tests: store task_id/after_seq filtering + pagination across memory/db/jsonl,
the /events route forwarding, stepsForDisplay rules, and fetchSubtaskSteps
pagination. Docs updated in both AGENTS.md.
* make format
* fix(subagents): capture full multi-tool step tail, batch step persistence, cap tool-call args (#3779)
Address PR review findings on the subagent step-history feature:
1. executor.py streamed on stream_mode="values" and captured only
messages[-1] per chunk, so a multi-tool-call turn (ToolNode appends
one ToolMessage per call in a single super-step) lost all but the last
tool output in both the live task_running stream and the persisted
history. Replace with capture_new_step_messages, which walks the
newly-appended tail (and still re-checks the trailing message on
no-growth chunks so id-less in-place replacements survive).
2. worker.py persisted each step with the store's low-frequency put()
(a per-thread advisory lock per call); a deep subagent (max_turns=150)
emits hundreds of steps on the hot stream loop. Replace with
_SubagentEventBuffer, which batches via put_batch (flush on terminal
subagent.end, at FLUSH_THRESHOLD, and in the worker finally).
3. build_subagent_step capped only text; tool_calls[].args were copied
verbatim, so a large write_file/bash payload produced an unbounded
subagent.step row. Cap each call's serialized args at
SUBAGENT_STEP_MAX_CHARS, flagged args_truncated.
Tests updated/added for all three; AGENTS.md refreshed.
* fix(subagents): merge backfill into latest subtask state; reuse message_content_to_text (#3779)
Address the remaining two PR review findings:
4. subtask-card's fetchSubtaskSteps().then(updateSubtask) closed over a
stale tasks snapshot: a late-resolving backfill wrote setTasks({...stale}),
clobbering SSE steps/status and sibling subtasks that arrived during the
fetch. useUpdateSubtask now reads/writes through a tasksRef mirroring the
latest state (ref-to-latest), and the pure per-subtask transition is
extracted to core/tasks/subtask-update.ts::computeNextSubtask (unit-tested).
5. step_events._content_to_text duplicated deerflow.utils.messages.
message_content_to_text; call the shared helper instead (guarding None
content with 'or ""' so a tool-call-only turn still renders as "").
Tests added for computeNextSubtask and the None-content case; AGENTS.md docs updated.
After SummarizationMiddleware runs, the merged conversation view could drop
already-displayed messages (previous assistant output, current user input),
leaving a nearly-empty thread.
Root cause: the display merge combines `visibleHistory` (archived history, a
React `useState` in useThreadHistory) with `persistedMessages` (live thread,
the LangGraph SDK external store via useSyncExternalStore). On summarization
the backend removes every live message and onUpdateEvent re-archives them via
an async `appendMessages` setState. Those two state systems are scheduled
independently, so a render can observe the post-summary (shrunk) thread before
the archive setState commits — the rescued messages are then absent from BOTH
merge inputs and get dropped.
Fix: bridge the async gap with a synchronous `pendingArchivedMessagesRef`
buffer written the moment onUpdateEvent computes the moved messages and read by
the merge on every render, so correctness no longer depends on how the two
channels interleave. The buffer drains once history confirms absorption and
only injects messages missing from history (live copies stay authoritative,
order preserved). It is tagged with the thread it was captured from and the
merge overlays it only when that matches the viewed `threadId` (the same prop
visibleHistory is gated on), so it can never leak into another thread or the
new-chat screen — a read-only check, no render-phase ref mutation.
Extracts the moved-message derivation and the merge overlay into pure,
unit-tested helpers (computeSummarizationMovedMessages, resolvePreservedHistory,
pruneConfirmedArchivedMessages) with regression coverage for the full rescue
pipeline.
* fix(frontend): preserve chronological order of thread history after context compression
Iterate runs from newest to match backend `list_by_thread` (newest-first) and the prepend semantics of the history loader, so refreshed history renders in A→B→C→D→E→F order.
Fixes#3352
* fix(frontend): auto-continue loading runs with no visible messages after context compression
