[wandamora]

Description

Refactors Function Kits installation (src/functions/kits/install.ts and src/functions/kits/install.spec.ts) following #11370 to consume KitSourceAdapter (createNpmPackageAdapter / createDirectoryAdapter) and separate kit-level setup, instance resolution, and project configuration, with no user-facing behavior changes:

• 3-stage linear install pipeline (install.ts): Simplifies installKitOrInstance into three source-agnostic stages:
  1. ensureKit: Resolves an existing kit via adapter.findExistingKit or validates, prepares (adapter.prepareSource), and stages the new kit in-memory (write: false).
  2. resolveOrCreateInstance: Creates a new kit instance (addInstanceToKitConfig, which persists both the staged kit and instance to firebase.json) or selects an existing unconfigured instance for the active project (promptExistingInstanceForProject).
  3. configureInstanceForProject: Seeds .env.<projectId>, discovers build parameters (discoverKitBuild), and prompts for values (promptAndWriteKitParams).
• Orchestration & Reporting: Success logging and printKitFirstDeployReport run in installKitOrInstance after pipeline completion, branching directly on isNewKit and isNewInstance.
• Remove legacy source helpers: Removes KitSource, resolvePackageSource, resolveDirectorySource, findExistingKit, scaffoldKit, and addKitInstanceOrConfigureProject in favor of the unified KitSourceAdapter pipeline.
• Standardize options interfaces: Consolidates multi-argument helper signatures in install.ts (getUnconfiguredInstancesForProject, promptExistingInstanceForProject, discoverKitBuild, printKitFirstDeployReport, promptAndWriteKitParams) into explicit *Options interfaces.

Scenarios Tested

• Unit tests across src/functions/kits/**/*.spec.ts, src/commands/functions-kits-install.spec.ts, and src/extensions/migrate.spec.ts.
• Installing a new kit from an npm package (--package) and from a local directory (--directory).
• Adding a second instance to an already-installed kit and configuring an existing unconfigured instance for another project.
• Atomic rollback and cleanup when installation or parameter resolution fails mid-flow.

Sample Commands

No CLI flags or commands changed:

firebase functions:kits:install --package @firebase-function-kits/firestore-bigquery-export
firebase functions:kits:install --directory ./my-local-kit

[gemini-code-assist]

Code Review

This pull request refactors the function kits installation logic by extracting source-specific handling into a modular adapter pattern under src/functions/kits/sources/. It introduces KitSourceAdapter implementations for both local directory and NPM package sources, simplifying install.ts into a clean three-stage orchestration flow. Feedback on the changes highlights several potential TypeError vulnerabilities where fs.readJson could return null and cause crashes on property access. Additionally, multiple functions accepting more than three arguments violate the repository style guide and should be refactored to accept a single options object.

[ajperel]

I think we pushed a bit too much into the different stage methods and shouldn't need action and isNewKit in them, but overall, I think this is a good improvement. Thanks for taking the time to do it.

[ajperel]

I was probably a bit stingy not just approving with my last round of comments so just doing it now. Haven't re-reviewed. I trust you to address the feedback.