Bundle Change Comments

Post bundle size diffs as a structured table in your PR. Use the CUSTOM_TABLE template to show route-level changes, size deltas, and status indicators — so reviewers can catch regressions before merge.

What you’ll build

A sticky comment with a table showing each route’s size and change from the base branch:

Route	Size	Δ	Status
`/`	45.2 KB	+2.1 KB	⚠️ Watch
`_app`	12.3 KB	-0.5 KB	✅ Improved

Workflow example

Compute bundle sizes in your CI, then pass the results to the CUSTOM_TABLE template:


- name: Post Bundle Size Analysis
  uses: dev-herald/comment@v1
  with:
    api-key: ${{ secrets.DEV_HERALD_API_KEY }}
    pr-number: ${{ github.event.pull_request.number }}
    template: CUSTOM_TABLE
    sticky-id: bundle-analysis
    template-data: |
      {
        "title": "Bundle Size Analysis",
        "headers": ["Route", "Size", "Change", "Status"],
        "rows": [
          {
            "cells": [
              { "markdown": "[/](/)" },
              { "markdown": "45.2 KB" },
              { "markdown": "+2.1 KB ⬆️" },
              { "markdown": "⚠️ Watch" }
            ]
          },
          {
            "cells": [
              { "markdown": "_app" },
              { "markdown": "12.3 KB" },
              { "markdown": "-0.5 KB ⬇️" },
              { "markdown": "✅ **Improved**" }
            ]
          }
        ],
        "showTimestamp": true
      }

Dynamic data from CI

Use a script step to compute bundle sizes and write template-data dynamically:


- name: Analyze bundle size
  id: bundle
  run: |
    # Your bundler analysis script here — output JSON to bundle-report.json
    node scripts/analyze-bundle.js > bundle-report.json
 
- name: Post Bundle Size Analysis
  uses: dev-herald/comment@v1
  with:
    api-key: ${{ secrets.DEV_HERALD_API_KEY }}
    pr-number: ${{ github.event.pull_request.number }}
    template: CUSTOM_TABLE
    sticky-id: bundle-analysis
    template-data: ${{ steps.bundle.outputs.template-data }}

Each cell supports full GitHub-Flavored Markdown — links, bold, code, and emoji all render correctly in the PR comment.

Tips

Use a consistent sticky-id (e.g., bundle-analysis) so the comment updates on every push
Add if: always() if your analysis step can fail but you still want to post partial results
Compare against your base branch in the analysis script to compute meaningful deltas

Next steps

See all Custom Table template fields
For ongoing bundle tracking across your codebase (not just per-PR), see Health Reports and the Signals reference