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feat(webapp): add emission fan-out metrics to the native realtime feed - #4341

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ericallam merged 3 commits into
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perf/realtime-serialize-hotpath
Jul 22, 2026
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feat(webapp): add emission fan-out metrics to the native realtime feed#4341
ericallam merged 3 commits into
mainfrom
perf/realtime-serialize-hotpath

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Summary

Adds two counters to the native realtime backend so we can see how much duplicate row serialization the change router does per batch. When a run changes it can match several held feeds at once (a run subscription plus one or more tag/list feeds), and today each matching feed serializes that run's wire value independently. These counters quantify that fan-out so we can decide whether a shared serialization step is worth it.

What they measure

  • realtime_native.emission_run_serializations: total wire-value serializations performed across feeds per batch (what the current path does).
  • realtime_native.emission_distinct_serializations: distinct (columns, run) rows those serializations cover (what a serialize-once-per-batch step would do).

Average feeds-per-run is run_serializations / distinct_serializations, and 1 - distinct / run_serializations is the serialization work a shared step could save. Wired through a new optional onEmissionFanout callback on the router. No behavior change.

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Latest commit: 2b5e753

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

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Review Change Stack

Walkthrough

Adds per-batch realtime emission fanout statistics to EnvChangeRouter, including total feed row deliveries and distinct (columnSig, runId) serializations. The native realtime client exposes Prometheus counters and records these values through the router callback. A changelog entry documents the new metrics.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

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Description check ⚠️ Warning The description misses required template sections like Closes #, checklist, testing, changelog, and screenshots. Add the missing template sections, including issue link, checklist items, testing steps, changelog entry, and screenshots or N/A.
✅ Passed checks (4 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 summarizes the main change: adding emission fan-out metrics to the native realtime feed.
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@ericallam
ericallam marked this pull request as ready for review July 22, 2026 16:21

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✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no bugs or issues to report.

Open in Devin Review

@ericallam
ericallam merged commit a2d382b into main Jul 22, 2026
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@ericallam
ericallam deleted the perf/realtime-serialize-hotpath branch July 22, 2026 16:48
@github-actions github-actions Bot mentioned this pull request Jul 24, 2026
carderne pushed a commit that referenced this pull request Jul 27, 2026
## Summary
2 new features, 9 improvements, 3 bug fixes.

## Highlights

- Allow additional environment API keys to create scoped public access
tokens through the Trigger.dev API. Use server-issued public access
tokens for batch operations so environment-scoped API keys can read
batch results.
([#4387](#4387))

## Improvements
- Preserve the partial assistant message when a chat turn's model stream
fails mid-response. `chat.agent` now passes the recovered partial to
`onTurnComplete`, and `chat.createSession`'s `turn.complete()` keeps it
before rethrowing, instead of dropping the streamed-so-far output.
([#4348](#4348))

## Server changes

These changes affect the self-hosted Docker image and Trigger.dev Cloud:

- Favorite any dashboard page to a new Favorites section in the side
menu, and customize the sidebar by renaming favorites, hiding items, and
reordering items and sections.
([#4375](#4375))
- List API endpoints now clamp the page size to a maximum of 100.
Requests asking for a larger page size return up to 100 items and keep
paginating, rather than pulling an unbounded page.
([#4360](#4360))
- Organizations without billing alerts now get default spend alert
thresholds, so you're notified before usage grows unexpectedly. The
billing limit page no longer pre-selects an option before you've set a
limit and prompts you to configure one. Alert previews now update
immediately after you change your billing limit.
([#4328](#4328))
- When you create a Personal Access Token, the generated token now shows
its first and last few characters instead of being fully hidden, so you
can confirm you copied the right value.
([#4363](#4363))
- Add metrics to the realtime backend that measure how often a single
changed run is served to multiple subscriptions in one batch.
([#4341](#4341))
- Realtime run subscriptions can now be configured to read run data
straight from the primary database, so a run's latest state is never
served from a lagging replica. Off by default; replica reads are
unchanged unless you turn it on.
([#4378](#4378))
- SSO and Directory Sync are no longer restricted to Enterprise plans —
get in touch and we can turn them on for your organization whatever plan
you're on.
([#4393](#4393))
- Improved supervisor observability: it now reports metrics for its
outbound requests, making failed calls to upstream services easier to
monitor.
([#4350](#4350))
- The runs list on a task's page now updates live — run statuses change
and newly triggered runs appear without a manual refresh, matching the
main Runs page.
([#4377](#4377))
- Speed up the Batches list page for environments with a large number of
batches, which could previously time out while loading.
([#4361](#4361))
- Container startup no longer prints database and ClickHouse connection
strings (with credentials) to the logs.
([#4346](#4346))
- The tasks page no longer runs two queries whose results were never
displayed, cutting wasted work on every page load and removing a source
of hidden server errors
([#4380](#4380))

<details>
<summary>Raw changeset output</summary>

# Releases
## @trigger.dev/build@4.5.8

### Patch Changes

- Updated dependencies:
  - `@trigger.dev/core@4.5.8`
## trigger.dev@4.5.8

### Patch Changes

- Updated dependencies:
  - `@trigger.dev/core@4.5.8`
  - `@trigger.dev/build@4.5.8`
  - `@trigger.dev/schema-to-json@4.5.8`
## @trigger.dev/core@4.5.8

### Patch Changes

- Allow additional environment API keys to create scoped public access
tokens through the Trigger.dev API. Use server-issued public access
tokens for batch operations so environment-scoped API keys can read
batch results.
([#4387](#4387))
## @trigger.dev/python@4.5.8

### Patch Changes

- Updated dependencies:
  - `@trigger.dev/sdk@4.5.8`
  - `@trigger.dev/core@4.5.8`
  - `@trigger.dev/build@4.5.8`
## @trigger.dev/react-hooks@4.5.8

### Patch Changes

- Updated dependencies:
  - `@trigger.dev/core@4.5.8`
## @trigger.dev/redis-worker@4.5.8

### Patch Changes

- Updated dependencies:
  - `@trigger.dev/core@4.5.8`
## @trigger.dev/rsc@4.5.8

### Patch Changes

- Updated dependencies:
  - `@trigger.dev/core@4.5.8`
## @trigger.dev/schema-to-json@4.5.8

### Patch Changes

- Updated dependencies:
  - `@trigger.dev/core@4.5.8`
## @trigger.dev/sdk@4.5.8

### Patch Changes

- Preserve the partial assistant message when a chat turn's model stream
fails mid-response. `chat.agent` now passes the recovered partial to
`onTurnComplete`, and `chat.createSession`'s `turn.complete()` keeps it
before rethrowing, instead of dropping the streamed-so-far output.
([#4348](#4348))
- Allow additional environment API keys to create scoped public access
tokens through the Trigger.dev API. Use server-issued public access
tokens for batch operations so environment-scoped API keys can read
batch results.
([#4387](#4387))
- Updated dependencies:
  - `@trigger.dev/core@4.5.8`

</details>

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
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2 participants