feat: celebrate bundle size decreases and report no-change by bartveneman · Pull Request #137 · e18e/action-dependency-diff

bartveneman · 2026-03-23T19:00:02Z

The machines did all the implementation for me, but I prompted them extensively with test cases to cover, which is hopefully reflected in the amount of tests.

Setting pack-size-threshold to -1 now shows 🎉 when bundle size decreases, and ⚠️ when it increases (reporting all changes)
When packed bundle size diff is 0, a No bundle size changes message is posted instead of silently doing nothing
Add tests for all new bundle-size behaviors
Update README and action.yml docs for pack-size-threshold=-1

closes #136

- Setting pack-size-threshold to -1 now shows 🎉 when bundle size decreases, and ⚠️ when it increases (reporting all changes) - When packed bundle size diff is 0, a "No bundle size changes" message is posted instead of silently doing nothing - Add tests for all new bundle-size behaviors - Update README and action.yml docs for pack-size-threshold=-1 https://claude.ai/code/session_01Mdf48qd8iQh4WG1F1dbHT1

github-actions · 2026-03-23T19:00:39Z

⚠️ Duplicate Dependencies (found: 3, threshold: 1)

📦 Package	📋 Versions
@actions/http-client	2 versions @e18e/action-dependency-diff@0.0.1 @actions/github@9.0.0 @actions/http-client@3.0.2 @e18e/action-dependency-diff@0.0.1 @actions/core@3.0.0 @actions/http-client@4.0.0
eslint-visitor-keys	2 versions @e18e/action-dependency-diff@0.0.1 eslint@10.0.3 @eslint-community/eslint-utils@4.9.1 eslint-visitor-keys@3.4.3 @e18e/action-dependency-diff@0.0.1 eslint@10.0.3 eslint-visitor-keys@5.0.1
ignore	2 versions @e18e/action-dependency-diff@0.0.1 eslint@10.0.3 ignore@5.3.2 @e18e/action-dependency-diff@0.0.1 typescript-eslint@8.57.1 @typescript-eslint/eslint-plugin@8.57.1 ignore@7.0.5

💡 To find out what depends on a specific package, run: npm ls example-package

…hold warnings The previous totalSizeChange === 0 check incorrectly triggered the "No bundle size changes" message when individual package changes cancelled each other out (e.g. one package shrinks by 100 kB while another grows by 100 kB). Replace with a per-package allUnchanged check so the message only fires when every package is truly unchanged. For the warning path, compare net total size change against the threshold rather than individual packages. This means if pkg-a shrinks 100 kB and pkg-b grows 100 kB with a 50 kB threshold, no warning is shown since the total bundle size is unchanged — consistent with how a size threshold over the total makes sense. Also add tests covering the two previously untested edge cases. https://claude.ai/code/session_01Mdf48qd8iQh4WG1F1dbHT1

src/checks/bundle-size.ts

43081j · 2026-03-23T21:45:08Z

generally looks good!

i do wonder though if its better ux to have a merged table?

i.e. show +2MB and -2MB etc in one table, so we have both added and removed dependencies instead of duplicating markup

what do you think? i can probably be swayed either way 😅

…ld is -1 Instead of two separate messages (one for 🎉 decreases, one for ⚠️ increases), all changed packages are now shown in a single table. The heading adapts based on direction: 🎉 for pure decreases, ⚠️ for pure increases, 📦 for mixed. The size change column uses signed values (negative for decreases) so direction is clear at a glance. Update tests and README accordingly. https://claude.ai/code/session_01Mdf48qd8iQh4WG1F1dbHT1

Add a formatBytesSigned helper that prefixes positive values with '+' so the size change column is unambiguous in both the threshold=-1 path (which can mix increases and decreases) and the threshold>0 warning path. https://claude.ai/code/session_01Mdf48qd8iQh4WG1F1dbHT1

bartveneman · 2026-03-24T07:51:42Z

I think that's a very good point, made the change. Also added - and + indicators to the changed sizes for clarity, now that they're in the same table.

When pack-size-threshold is not set (defaults to 50000) and bundle sizes are unchanged, no message should appear — consistent with how all other checks behave: stay silent unless a threshold is exceeded. The 'No bundle size changes' message is now scoped to threshold=-1, which is the only mode where the user has opted into always seeing output. Add a test covering the no-op case for threshold>0 and move the explicit assertion for the no-change message into the threshold=-1 test. https://claude.ai/code/session_01Mdf48qd8iQh4WG1F1dbHT1

43081j · 2026-03-24T21:10:44Z

src/checks/bundle-size.ts

+    return;
+  }
+
+  const totalSizeChange = comparison.packChanges.reduce(


does this need Math.abs or is the change.sizeChange always positive?

i.e. so totalSizeChange < threshold works whether it is negative or positive

README.md

The message is only posted when pack-size-threshold is -1, not for the default threshold. Update the docs to reflect this. https://claude.ai/code/session_01Mdf48qd8iQh4WG1F1dbHT1

Summing all sizeChanges (positive and negative) meant a large decrease in one package could mask a large increase in another, causing the threshold check to silently skip a real warning. Now only positive changes are summed for the threshold comparison, consistent with the warning table which already filters to increases. sizeChange is signed ((sourceSize ?? 0) - (baseSize ?? 0)), so no Math.abs is needed — filtering to > 0 is sufficient and correct. https://claude.ai/code/session_01Mdf48qd8iQh4WG1F1dbHT1

… change Three new cases that directly encode the reasoning from the fix: 1. A pure decrease, however large, never triggers a warning — sizeChange is signed so a shrink produces a negative value that cannot exceed a positive threshold. 2. A large decrease in one package does not mask an increase in another even when the net total is negative — the old sum-all approach would have returned -400 KB < 50 KB and stayed silent. 3. Multiple sub-threshold increases are summed together and can collectively exceed the threshold — two ×30 KB increases (each below 50 KB) combine to 60 KB and trigger the warning. https://claude.ai/code/session_01Mdf48qd8iQh4WG1F1dbHT1

43081j · 2026-03-25T18:08:53Z

src/checks/bundle-size.ts

+    .filter((change) => change.sizeChange > 0)
+    .reduce((sum, change) => sum + change.sizeChange, 0);
+
+  if (totalSizeChange < threshold) {


in main, we basically check if any packages exceeded the threshold. this checks if the sum of packages exceeds the threshold.

are we sure this bit is needed?

maybe we could just do what we did originally:

const packWarnings = comparison.packChanges.filter( (change) => change.exceedsThreshold && change.sizeChange > 0 ); if (packWarnings.length > 0) {

i.e. if any package exceeds the threshold, show the table.

otherwise this will show the table if no packages exceed the threshold, but their total change does.

Oh, my brain went "that'd be nice as a guard rail" but no worries, I'll revert that bit 👌

bartveneman marked this pull request as ready for review March 23, 2026 19:13

43081j reviewed Mar 23, 2026

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bartveneman added 2 commits March 24, 2026 07:46

43081j reviewed Mar 24, 2026

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bartveneman added 3 commits March 25, 2026 08:37

docs: correct README description of no-change bundle size behaviour

e411595

The message is only posted when pack-size-threshold is -1, not for the default threshold. Update the docs to reflect this. https://claude.ai/code/session_01Mdf48qd8iQh4WG1F1dbHT1

43081j reviewed Mar 25, 2026

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feat: celebrate bundle size decreases and report no-change#137

feat: celebrate bundle size decreases and report no-change#137
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