feat(Slack Node): Add emoji reaction filter to Slack Trigger

[Joffcom]

Summary

Adds an optional Emoji Names to Filter field to the Slack Trigger node (under Options). When configured, only reaction_added events matching the allowlist will start a workflow execution — reactions not in the list are dropped before execution begins, saving execution budget for high-volume Slack workspaces.

How to test:

1. Create a Slack Trigger node with Trigger On: Reaction Added
2. Open Options → Emoji Names to Filter and enter thumbsup
3. Add a 👍 reaction to a message → workflow executes
4. Add a 👀 reaction → no execution
5. Clear the field → all reactions trigger (existing behavior preserved)

Notes:

• Emoji names are comma-separated, without colons (e.g. thumbsup, eyes, white_check_mark)
• Matching is case-insensitive and whitespace-trimmed
• Empty field (default) = no filtering, fully backwards-compatible

Related Linear tickets, Github issues, and Community forum posts

https://linear.app/n8n/issue/NODE-4101

Community forum: https://community.n8n.io/t/how-to-minimize-workflow-executions-for-cost-saving-in-n8n/162301/2

Review / Merge checklist

• I have seen this code, I have run this code, and I take responsibility for this code.
• PR title and summary are descriptive. (conventions)
• Docs updated or follow-up ticket created.
• Tests included.
• PR Labeled with Backport to Beta, Backport to Stable, or Backport to v1 (if the PR is an urgent fix that needs to be backported)

🤖 PR Summary generated by AI

[codecov]

Codecov Report

❌ Patch coverage is 85.71429% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...ckages/nodes-base/nodes/Slack/SlackTrigger.node.ts	85.71%	0 Missing and 1 partial ⚠️

📢 Thoughts on this report? Let us know!

[cubic-dev-ai]

1 issue found across 2 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="packages/nodes-base/nodes/Slack/SlackTrigger.node.ts">

<violation number="1" location="packages/nodes-base/nodes/Slack/SlackTrigger.node.ts:393">
P2: Gate emoji filtering by selected trigger to avoid stale hidden `reactionEmojis` values affecting `any_event` setups. According to linked Linear issue NODE-4101, filtering is intended for the Reaction Added trigger path.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review, or fix all with cubic.}

[github-actions]

Performance Comparison

Comparing current → latest master → 14-day baseline

Idle baseline with Instance AI module loaded

Metric	Current	Latest Master	Baseline (avg)	vs Master	vs Baseline	Status
instance-ai-heap-used-baseline	186.85 MB	186.83 MB	186.46 MB (σ 0.26)	+0.0%	+0.2%	⚠️
instance-ai-rss-baseline	341.09 MB	343.82 MB	366.71 MB (σ 22.88)	-0.8%	-7.0%	⚠️

docker-stats

Metric	Current	Latest Master	Baseline (avg)	vs Master	vs Baseline	Status
docker-image-size-runners	387.00 MB	387.00 MB	391.94 MB (σ 10.84)	+0.0%	-1.3%	✅
docker-image-size-n8n	1269.76 MB	1290.24 MB	1274.58 MB (σ 10.93)	-1.6%	-0.4%	✅

Memory consumption baseline with starter plan resources

Metric	Current	Latest Master	Baseline (avg)	vs Master	vs Baseline	Status
memory-rss-baseline	280.97 MB	286.68 MB	289.59 MB (σ 40.91)	-2.0%	-3.0%	✅
memory-heap-used-baseline	114.60 MB	114.56 MB	114.47 MB (σ 0.23)	+0.0%	+0.1%	✅

How to read this table

• Current: This PR's value (or latest master if PR perf tests haven't run)
• Latest Master: Most recent nightly master measurement
• Baseline: Rolling 14-day average from master
• vs Master: PR impact (current vs latest master)
• vs Baseline: Drift from baseline (current vs rolling avg)
• Status: ✅ within 1σ | ⚠️ 1-2σ | 🔴 >2σ regression

[n8n-assistant]

Got released with n8n@2.19.0