fix(cloud): retry transient event delivery failures by Kinfe123 · Pull Request #8023 · assistant-ui/assistant-ui

Kinfe123 · 2026-09-22T23:26:57Z

Problem

On current main, a rejected /events request permanently drops its dequeued engagement-event batch. A minimal reproduction is to fill the 20-event flush threshold and reject the first request; the batch is no longer available for a later flush.

Closes #8017.

Root cause

The batch was removed from the buffer before the request and the rejection was swallowed without retrying that batch.

Change

Use bounded retries for ordinary flushes: the initial request plus two retries after 250 ms and 1 second. The same batch is retained across attempts. Page hide, visibility hide, and disposal remain single-attempt best-effort delivery so page teardown is never delayed. Disabling telemetry still discards pending data immediately.

Verification

pnpm --filter assistant-cloud test (270 tests on the current peer lane and 270 on the v6 peer lane, plus v6 type tests)
pnpm --filter assistant-cloud typecheck
pnpm --filter assistant-cloud... build
Regression coverage verifies retry timing, batch identity, the three-attempt cap, and best-effort disposal.

Public surface

Affected package: assistant-cloud
Exports, API reference, docs, and templates: None
Patch changeset included

rupic-app · 2026-09-22T23:27:02Z

Reviewed in 9m 29s · Round 3 · comment · 5a6a3be

Merge as is — bounded event retries preserve ordinary batches and lifecycle flushes stay best effort

This PR should merge as-is: #8017 identifies a real batch-loss bug, and packages/cloud/src/AssistantCloudEvents.ts now keeps ordinary batches across the bounded retry loop while lifecycle flushes interrupt backoff and suppress later retries. The colocated tests cover both retry boundaries and the lifecycle paths that previously left requests pending. Review threads are resolved; the current CI rollup still has pending work, so code readiness is established separately from completed CI.

Prior findings

Finding	Status
`packages/cloud/src/AssistantCloudEvents.ts:102` — lifecycle flush could not preempt ordinary retry backoff	Resolved — Resolved by `bestEffortRequested` and `interruptRetryDelay()` at `packages/cloud/src/AssistantCloudEvents.ts:98-103,177-180`; `flushPending()` abandons the remaining retry and drains buffered events, covered at `AssistantCloudEvents.test.ts:135-156`.
`packages/cloud/src/AssistantCloudEvents.ts:139` — disposal left the retry timer active	Resolved — Resolved because `dispose()` calls `flushBestEffort()` after clearing the ordinary timer, and the best-effort path clears and resolves the retry handle; the dispose case asserts no later request at `AssistantCloudEvents.test.ts:146-155`.
`packages/cloud/src/AssistantCloudEvents.test.ts` — lifecycle actions during ordinary retry backoff lacked coverage	Resolved — Resolved by the parameterized backoff test at `packages/cloud/src/AssistantCloudEvents.test.ts:135-156`, which exercises `pagehide` and `dispose()` after a failed threshold flush, asserts the single follow-up request, and drains timers to rule out later retries.
`packages/cloud/src/AssistantCloudEvents.test.ts:103` — retry-cap test did not pin the second boundary	Resolved — Resolved by the assertions at `packages/cloud/src/AssistantCloudEvents.test.ts:111-119`, which pin the 250 ms and 1-second boundaries before checking that no fourth attempt occurs.

Review threads

stale: issue cloud: transient event delivery failures discard buffered engagement events #8017 triage, 2026-09-22 by @rupic-app: The triage predates PR fix(cloud): retry transient event delivery failures #8023, so its statement that no linked PR covers cloud: transient event delivery failures discard buffered engagement events #8017 is no longer current; its diagnosis of real batch loss remains the necessity evidence.

Merge state: The PR is open, non-draft, and mergeable; stored review threads are resolved and human approval state is unknown. The live CI rollup reports 22 completed runs (17 success, 5 skipped) and 2 pending; this is operational state only.

Evidence · 6 verified · 1 not verified

Verified

A rejected /events request can permanently drop its dequeued engagement-event batch.
The issue is a real unsolved failure mode on the pre-change path, and the current code directly addresses that mechanism.
Ordinary flushes retry the same batch after 250 ms and 1 second, with three attempts maximum.
The control flow and boundary assertions establish the claimed schedule and cap without requiring an API change.
Pagehide, visibility hide, and disposal remain single-attempt best-effort delivery.
The shared callback and its interruption branch cover all three lifecycle entrypoints; the targeted lifecycle tests cover the prior delayed-flush failure.
Disabling telemetry still discards pending event data without sending it.
The new retry path preserves the existing disablement branch and its regression coverage.
No exports, API reference, documentation, or templates changed.
The changed behavior does not invalidate the existing documentation statement that delivery failures do not surface.
A patch changeset is included for assistant-cloud.
The release metadata matches the repository's patch-default rule.

Not verified

The focused cloud tests, typecheck, and build checks passed.
The pending test run must conclude successfully to establish the full verification claim; this review did not execute project commands.

This delta re-review read the supplied full PR diff because no interdiff was available, all four changed files at head, surrounding cloud callers and docs, root governance files, prior reviews/threads/comments, and live PR/issue state. No project code, tests, typechecks, or builds were executed. Live CI reported 22 completed and 2 pending runs; all four ledger findings were re-checked rather than carried.

Round	Commit	Verdict	Took	When
1	`104b696`	comment	2m 50s	2026-09-22 23:31 UTC
2	`2406090`	comment	2m 29s	2026-09-22 23:36 UTC
3	`5a6a3be`	comment	9m 29s	2026-09-23 00:02 UTC

Comment @rupic-app stop reviewing to stop reviewing this PR.

Review by Rupic.

changeset-bot · 2026-09-22T23:27:03Z

🦋 Changeset detected

Latest commit: 5a6a3be

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

This PR includes changesets to release 1 package

Name	Type
assistant-cloud	Patch

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claude · 2026-09-22T23:27:28Z

Re-review in progress

Read the updated AssistantCloudEvents.ts
Re-check my two prior findings against the new commits
Review the new interrupt mechanism for fresh defects
Run the cloud test suite

View job run · branch fix/cloud-event-delivery-retry

cubic-dev-ai

All reported issues were addressed across 3 files

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coderabbitai · 2026-09-22T23:43:57Z

Navigate logical layers of code changes, visualize relationships, and explore their blast radius.

Walkthrough

AssistantCloudEvents now retries failed event batches after 250 ms and 1,000 ms delays, for up to three attempts. Lifecycle events and dispose interrupt retry waits and perform one best-effort flush. Tests cover retry timing, retry limits, disposal, and pagehide behavior. The assistant-cloud size budgets are increased.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~20 minutes

Severity of issue fixed: Medium

Merge Risk: 🟡 Moderate · up to 5a6a3

Before merging, ensure disabled telemetry is discarded immediately and event retries cannot duplicate engagement metrics.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely identifies the main change: retrying transient event delivery failures in the cloud package.
Description check	✅ Passed	The description directly explains the event delivery failure, bounded retry behavior, best-effort teardown behavior, implementation scope, and verification coverage.
Linked Issues check	✅ Passed	Issue [`#8017`] requires bounded retries for failed event batches, preserved event order, immediate discard when telemetry is disabled, and best-effort unload behavior. `AssistantCloudEvents.ts` retains…
Out of Scope Changes check	✅ Passed	The changed source implements the retry behavior required by [`#8017`]. The regression tests verify that behavior. The `size-budgets.json` update supports the resulting package size change. The summary …
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 2…

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Actionable comments posted: 1

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🤖 Prompt to fix review comments

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Inline comments:
In `@packages/cloud/src/AssistantCloudEvents.ts`:
- Around line 149-160: Update the telemetry mutation boundary for the mutable
enabled/events fields so disabling telemetry immediately clears buffer and
cancels any pending waitForRetry in flushPending. Ensure a retry cannot resume
and resend the failed batch if telemetry is re-enabled before the delay
completes, while preserving the existing isEnabled check as a safeguard.

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ℹ️ Review info

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Configuration used: Organization UI

Review profile: CHILL

Plan: Advanced

Run ID: f89fc462-8e55-42d5-bbe3-4bb83738b351

📥 Commits

Reviewing files that changed from the base of the PR and between 5496fce and 5a6a3be.

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📒 Files selected for processing (3)

packages/cloud/src/AssistantCloudEvents.test.ts
packages/cloud/src/AssistantCloudEvents.ts
size-budgets.json

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fix(cloud): retry transient event delivery failures

104b696

Kinfe123 requested a review from a team September 22, 2026 23:26

rupic-app Bot added stage/needs-review No reviews yet; waiting for a maintainer pkg/cloud Changes a package under packages/ R0 Act now: stale, blocked, or high impact type/bugfix Bug fix size/M 50–199 lines changed labels Sep 22, 2026

claude Bot reviewed Sep 22, 2026

View reviewed changes

Comment thread packages/cloud/src/AssistantCloudEvents.ts

rupic-app Bot added stage/awaiting-reviewer Has reviews but not approved; reviewer follow-up needed and removed stage/needs-review No reviews yet; waiting for a maintainer labels Sep 22, 2026

[autofix.ci] apply automated fixes

2406090

claude Bot reviewed Sep 22, 2026

View reviewed changes

Comment thread packages/cloud/src/AssistantCloudEvents.ts

cubic-dev-ai Bot reviewed Sep 22, 2026

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Comment thread packages/cloud/src/AssistantCloudEvents.ts Outdated

Comment thread packages/cloud/src/AssistantCloudEvents.test.ts Outdated

fix(cloud): interrupt event retry backoff

bfea8db

Kinfe123 and others added 2 commits September 22, 2026 16:45

test(cloud): pin event retry backoff boundaries

6ec696b

[autofix.ci] apply automated fixes

5a6a3be

coderabbitai Bot reviewed Sep 23, 2026

View reviewed changes

Comment thread packages/cloud/src/AssistantCloudEvents.ts

Kinfe123 merged commit 920422c into main Sep 23, 2026
26 checks passed

Kinfe123 deleted the fix/cloud-event-delivery-retry branch September 23, 2026 00:07

rupic-app Bot added stage/merged Merged into the default branch and removed stage/awaiting-reviewer Has reviews but not approved; reviewer follow-up needed R0 Act now: stale, blocked, or high impact labels Sep 23, 2026

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fix(cloud): retry transient event delivery failures - #8023

fix(cloud): retry transient event delivery failures#8023
Kinfe123 merged 5 commits into
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fix/cloud-event-delivery-retry

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