feature: functions can now declare lifecycle hooks

[wandamora]

Description

This PR adds support for declaring codebase lifecycle hooks in the Firebase Functions SDK. Developers can now register actions (afterInstall and afterUpdate) that are automatically executed post-deployment.

Summary of Changes

1. Hook Registrations (src/lifecycle/index.ts)

• Added new top-level entrypoints and types under firebase-functions/lifecycle:
  • afterInstall(action: LifecycleAction): Registers a hook to run when resources in the codebase are deployed for the first time.
  • afterUpdate(action: LifecycleAction): Registers a hook to run when resources in the codebase are updated.
• Supported action types:
  • task: Triggers a task queue function with an optional payload body.
  • call: Calls a function (callable trigger) with optional params.
  • http: Triggers a HTTP endpoint via request url/function, method, and body.
• Ensures only one instance of afterInstall and afterUpdate can be registered per codebase at runtime.

2. Stack Manifest Parsing (src/runtime/loader.ts, src/runtime/manifest.ts)

• Added ManifestLifecycleAction and updated ManifestStack types to include the lifecycleHooks field.
• Updated loadStack inside loader.ts to capture any declared lifecycle hooks from global symbols during function discovery, mapping them into the compiled JSON/wire format returned to firebase-tools.
• Updated stackToWire serialization helper to recursively resolve CEL expressions and reset values inside lifecycleHooks properties.

3. Tests

• Created spec/lifecycle/lifecycle.spec.ts to test hook registration and duplicate hook prevention.
• Added tests in spec/runtime/loader.spec.ts verifying that afterInstall and afterUpdate declarations are correctly discovered and serialized into the ManifestStack.

Code sample

export const runInitialSetup = onTaskDispatched(async (request) => {
  await performDatabaseSeeding(request.data);
});

// The CLI automatically discovers this call and queues the task after first-time deploy
afterInstall({
  task: {
    function: "runInitialSetup",
    body: { data: "default_catalog" }
  }
});

[gemini-code-assist]

Code Review

This pull request introduces support for post-deployment lifecycle hooks (afterInstall and afterUpdate) by adding a new lifecycle module, updating the manifest stack loader to capture these hooks, and exposing the module exports in package.json. The review feedback highlights a correctness issue in src/runtime/loader.ts where falsy but valid JSON values (such as 0 or false) are incorrectly omitted during serialization, and suggests using TypeScript union types in src/lifecycle/index.ts to enforce mutually exclusive properties at compile-time.