fix(bundle-analysis): publish analyzer.json as a separate bundleAnalyzerJson artifact

[ChumpChief]

Description

#27224 added analyzer.json to the existing bundleAnalysis pipeline artifact. The FF-internal telemetry handler (@ff-internal/telemetry-generator/dist/handlers/bundleSizeHandler.js) walks every .json file under that artifact and tries to parse each as a webpack stats file ({ assets: [...] }). analyzer.json is a top-level array, so the handler crashes with TypeError: fileData.assets is not iterable and breaks the build-client telemetry upload step.

Fix on our side instead of in the handler: move analyzer.json out of the bundleAnalysis artifact entirely. It now travels in its own parallel pipeline artifact, bundleAnalyzerJson, with its own staging directory at every stage of the producer/collect/publish pipeline.

The split also reflects a real distinction in audience and lifecycle:

• bundleAnalysis feeds the FF-internal size-telemetry dashboards. Contents (report.html, report.json, bundleStats.msp.gz) and consumer contract are owned by the internal telemetry handler.
• bundleAnalyzerJson feeds flub generate bundleSizeDiff (and the upcoming GH Actions PR-comparison workflow). Contents and shape are owned in this repo.

Keeping them in separate artifacts means we can iterate freely on the PR-comparison feed without coordinating with the FF-internal handler each time we want to change shape, add a file, etc.

Changes

• examples/utils/bundle-size-tests/webpack.config.cjs: emit analyzer.json to bundleAnalyzerJson/ instead of bundleAnalysis/.
• examples/utils/bundle-size-tests/package.json: clean script also wipes bundleAnalyzerJson/.
• .gitignore: ignore bundleAnalyzerJson/ alongside bundleAnalysis/.
• build-cli/src/commands/generate/bundleStats.ts: also collect any bundleAnalyzerJson/ folders from each package into artifacts/bundleAnalyzerJson/<package>/.
• build-cli/src/commands/generate/bundleSizeDiff.ts: switch the artifact name and local report path from bundleAnalysis → bundleAnalyzerJson.
• tools/pipelines/templates/build-npm-{client-,}package.yml: copy the new staging dir and publish bundleAnalyzerJson as a parallel pipeline artifact (only on non-PR builds, matching bundleAnalysis).

Validation

• pnpm webpack in bundle-size-tests emits to both bundleAnalysis/ and bundleAnalyzerJson/ directories correctly.
• flub generate bundleStats populates both artifacts/bundleAnalysis/<scope>/<pkg>/ and artifacts/bundleAnalyzerJson/<scope>/<pkg>/.
• 489 build-cli tests pass.

Reviewer Guidance

The review process is outlined on this wiki page.

The conceptual flow is straightforward — there's just a lot of mechanical plumbing the move has to thread through. Reviewing in this order may help: producer → collect → pipeline publish → consumer.

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[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Splits analyzer.json out of the existing bundleAnalysis pipeline artifact into a new parallel bundleAnalyzerJson artifact to prevent the FF-internal telemetry handler from mis-parsing it and breaking telemetry upload.

Changes:

• Emit and clean analyzer.json under bundleAnalyzerJson/ (producer side).
• Collect bundleAnalyzerJson/ into artifacts/bundleAnalyzerJson/<package>/ and update bundleSizeDiff to consume that artifact.
• Update Azure Pipelines templates to stage and publish the new bundleAnalyzerJson pipeline artifact.

Reviewed changes

Copilot reviewed 6 out of 7 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
tools/pipelines/templates/build-npm-package.yml	Stages and publishes new bundleAnalyzerJson artifact in CI builds.
tools/pipelines/templates/build-npm-client-package.yml	Stages and publishes new bundleAnalyzerJson artifact in CI builds (client template).
examples/utils/bundle-size-tests/webpack.config.cjs	Writes BundleAnalyzerPlugin output to bundleAnalyzerJson/analyzer.json.
examples/utils/bundle-size-tests/package.json	Extends clean script to remove bundleAnalyzerJson/.
build-tools/packages/build-cli/src/commands/generate/bundleStats.ts	Collects bundleAnalyzerJson/ into central artifacts directory.
build-tools/packages/build-cli/src/commands/generate/bundleSizeDiff.ts	Switches baseline artifact + local path from bundleAnalysis to bundleAnalyzerJson.
.gitignore	Ignores bundleAnalyzerJson/.