fix(sdk): watch-mode chat subscriptions survive quiet windows

[kathiekiwi]

Two related fixes to the chat transport's watch/read-only subscription lifecycle.

TRI-13065 — In watch mode the chat stream died at the first long-poll window boundary after a turn completed: the EOF-reconnect path was gated on isStreaming, which turn-complete clears, so a watcher stopped hearing later turns. Watch mode now keeps reconnecting across quiet windows and only stops on abort or a settled session. The bounded give-up budget still applies to normal (mid-turn) streams, but not to watch mode, where empty windows are expected.

TRI-13070 — reconnectToStream derived mutation rights from mere signal presence (sendStopOnAbort: !!options.abortSignal), so a passive/read-only subscriber that passed an abortSignal would append a {kind:"stop"} to .in on unmount and could stop a turn it didn't own. Subscription lifecycle is not session ownership: reconnectToStream now takes an explicit stopOnAbort option that defaults to false, and the owning turn paths (sendMessages, sendAction) pass sendStopOnAbort: true explicitly. A read-only subscription ending never mutates the session; it still cancels its own request.

[changeset-bot]

🦋 Changeset detected

Latest commit: 1fa556f

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 27 packages

Name	Type
@trigger.dev/sdk	Patch
@trigger.dev/python	Patch
@internal/dashboard-agent	Patch
@internal/sdk-compat-tests	Patch
@trigger.dev/build	Patch
@trigger.dev/core	Patch
@trigger.dev/react-hooks	Patch
@trigger.dev/redis-worker	Patch
@trigger.dev/rsc	Patch
@trigger.dev/schema-to-json	Patch
@trigger.dev/database	Patch
@trigger.dev/otlp-importer	Patch
@trigger.dev/rbac	Patch
@trigger.dev/sso	Patch
trigger.dev	Patch
@internal/cache	Patch
@internal/clickhouse	Patch
@internal/llm-model-catalog	Patch
@internal/metrics-pipeline	Patch
@internal/redis	Patch
@internal/replication	Patch
@internal/run-engine	Patch
@internal/run-store	Patch
@internal/schedule-engine	Patch
@internal/testcontainers	Patch
@internal/tracing	Patch
@internal/tsql	Patch

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Walkthrough

Watch mode now reconnects after completed turns and idle-window EOFs. It continues beyond the normal EOF resubscribe limit. The subscription stops when the session is settled or the operation is aborted. Tests cover reconnect behavior, settled-session termination, aborts during backoff, and updated SSE fixtures. A patch changeset documents the SDK change.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly and concisely describes the primary watch-mode chat subscription fix.
Description check	✅ Passed	The description clearly explains both fixes and their intended behavior, but it omits the template checklist and explicit testing, changelog, and screenshots sections.

✨ Finishing Touches 💡 1

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• Commit unit tests in branch fix/watch-mode-keepalive-tri-13065

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[devin-ai-integration]

Devin Review found 1 new potential issue.

[devin-ai-integration]

🟡 A viewer closing a chat view mid-reply can mark the reply as finished for every tab

A watching viewer that stops listening while waiting to re-open its connection has the chat recorded as no longer generating (state.isStreaming = false + notifySessionChange at packages/trigger-sdk/src/v3/chat.ts:1855-1857) even though the reply is still being produced, so returning to the chat shows a frozen half-written reply that never resumes.
Impact: A user who navigates away and back during an in-progress reply sees it stuck mid-sentence until the next message is sent.

How the abort-during-backoff path clears the persisted streaming flag

Before this PR the reconnect loop in resumeAfterEof only ran while state.isStreaming && eofResubscribes < MAX_EOF_RESUBSCRIBES, so watch-mode readers spent little time inside it. With the new condition (this.watchMode || ...) a watch-mode subscription now sits in this loop indefinitely across quiet windows, which makes the abort-during-backoff exit path the common one: combinedSignal.aborted breaks the loop, the new budget-exhausted throw is skipped (it requires !combinedSignal.aborted), and control falls into the pre-existing trailing block at packages/trigger-sdk/src/v3/chat.ts:1854-1858 which sets state.isStreaming = false and persists it via notifySessionChange.

This contradicts the TRI-13070 goal that "a read-only subscription ending never mutates the session": reconnectToStream deliberately no longer posts a stop chunk (stopOnAbort defaults to false at packages/trigger-sdk/src/v3/chat.ts:1177), yet the same passive abort still writes the session state consumers persist. Because reconnectToStream returns null when state.isStreaming === false (packages/trigger-sdk/src/v3/chat.ts:1165), a later remount/reload will refuse to resume the still-running turn.

Prompt for agents

In `subscribeToSessionStream`'s `resumeAfterEof` (packages/trigger-sdk/src/v3/chat.ts), the trailing block after the reconnect loop unconditionally clears and persists `state.isStreaming` when the loop exits. With the new watch-mode condition, the most common exit for a passive/watch subscriber is `combinedSignal.aborted` (the consumer unmounted or cancelled), and in that case the turn may still be running server-side. Clearing + persisting `isStreaming` there makes `reconnectToStream` refuse to resume on a later mount (it returns null when isStreaming is false), so the viewer is stuck on a truncated reply. Consider only clearing the flag when the exit is a genuine end-of-turn (settled session, or budget exhaustion in non-watch mode) and leaving session state untouched when the exit was caused by an abort of a subscription that does not own the turn (i.e. the same `sendStopOnAbort`/ownership signal already threaded through this function).

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