chore: update several packages, including firebase to v12.

[KingDarBoja]

Changes

• Switch ESLint to Flat Config.
• Peer dependencies updated to support only firebase v12 and above due to the renaming of firebase/vertexai to firebase/ai.
• Type fixes around a few definitions.
• Reconfigure rollup plugins with latest versions.

This should fix #122 and probably #93 and #94 as I managed to provide correct typing fixes to that.

I started doing this after seeing issues like angular/angularfire#3666 due to firebase v12 renaming the vertexai thingy.

[gemini-code-assist]

Summary of Changes

Hello @KingDarBoja, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request focuses on a significant dependency upgrade, primarily moving to Firebase version 12, which required adapting to API changes like the firebase/ai renaming. It also modernizes the project's development tooling by migrating to the new ESLint Flat Config system and updating build-related Rollup plugins. These updates ensure the project remains current, compatible with the latest Firebase ecosystem, and benefits from improved linting and build processes.

Highlights

• Firebase v12 Upgrade: The project's peer dependency on Firebase has been updated to version 12, necessitating changes due to the renaming of firebase/vertexai to firebase/ai and ensuring compatibility with other packages like @angular/fire v20.
• ESLint Flat Config Migration: The linting setup has been modernized by switching to ESLint Flat Config (ESLint v9), which involved adding a new eslint.config.mjs file and updating linting scripts.
• New AI Module: A new ai module has been introduced, providing an observable wrapper for firebase/ai's startAudioConversation function, along with its own package.json and documentation.
• Rollup Plugin Updates: Several Rollup plugins used for building have been updated, including the addition of @rollup/plugin-json, though a specific issue with @rollup/plugin-typescript v12.x.x regarding declaration files was noted and addressed by reverting to v11.
• Type Definition Enhancements: Various type definitions across auth, database, firestore, and firestore/lite modules have been refined and corrected for improved type safety and clarity.

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[gemini-code-assist]

Code Review

This pull request brings several important updates, including upgrading to Firebase v12, switching to ESLint's Flat Config, and adding support for firebase/ai. The dependency updates and configuration changes are well-executed. I've found a few areas for improvement, mainly around consistent use of modern RxJS APIs and improving type safety in a couple of spots. There's also a minor typo in a test file. Overall, this is a solid update that modernizes the project's tooling and dependencies.

[KingDarBoja]

@jamesdaniels any updates on this?

[tobiaschristensen]

Hi @davideast. Sorry for the ping, but is there someone who can take a look at this?

[KingDarBoja]

Hey @armando-navarro, do you want me to split the changes into smaller PRs (ESLint, rollup, etc) if applies?

[armando-navarro]

@KingDarBoja I'm actively investigating this. But yes, this needs to be split up for a number of reasons. Please await my report.

[armando-navarro]

Hey @KingDarBoja, thanks for the ping, and sorry for the long wait.

Yes, please split it. Also, main has changed considerably since you opened this:

• fix(version): accept firebase 12 in peer range #152 widened the firebase peer range to ^9.0.0 || ^10.0.0 || ^11.0.0 || ^12.0.0 in July, which closed Add support for Firestore v12 #122. So firebase 12 already works on main.
• That's also your one merge conflict (package.json).
• When you rebase, keep the widened range. Going ^12.0.0-only drops firebase 9 through 11, and that's a breaking change to decide on its own, not inside tooling work.

Two things to fix regardless of how you split the PR

I checked out the branch and ran what CI runs.

• yarn lint fails with 10 parsing errors ("was not found by the project service"): 8 files in test/, plus babel.config.js and rollup.config.js.

  • You can't just put all 10 in allowDefaultProject, it maxes out at 8 files. This got lint green for me: allowDefaultProject: ['babel.config.js', 'rollup.config.js'], plus a new test/tsconfig.json:

    {
      "extends": "../tsconfig.json",
      "compilerOptions": {
        "allowJs": true,
        "noEmit": true
      },
      "include": ["./**/*.ts", "./**/*.mjs"],
      "exclude": []
    }

    Don't skip the "exclude": []. The root tsconfig excludes test/ and that carries over without it.

• "type": "module" breaks jest. babel.config.js is CommonJS, so with that field set, Node won't load it and every suite dies before running anything. Just drop the field. The build doesn't need it, I checked: rollup 4 loads the ESM-syntax config fine either way, and tsc --emitDeclarationOnly is still clean.

How I would split things

In this order:

1. Type fixes first: the tap(next, error, complete) deprecation cleanups, the storage typings (StorageError, FullMetadata), and the CountSnapshot / Query generics.
   1. Heads up: firestore/lite already doesn't typecheck against firebase 9 on main (the TS2314 from CountSnapshot / TS2305 / Alguna ayuda al respecto #94), and the two-parameter Query adds one more line like that. Something to decide in that PR.
2. Tooling second: the ESLint 9 / flat config migration plus the rollup upgrades, with lint, build, and the emulator tests passing.
3. rxfire/ai as its own feature PR, with tests and docs.
   1. startAudioConversation is still @beta upstream, so whether rxfire should wrap it yet is the first thing to settle there.
   2. docs/ai.md is blank except the heading. Intentional?

Separate reformatting into its own PR if you want to submit them

Most of your changes are reformatting, so re-authoring on fresh branches will be easier than cherry-picking. Please keep formatting-only changes out of the code PRs (auth/index.ts here is whitespace and import layout only). If you want the reformat, send it as its own PR with a Prettier config checked in so it sticks. .vscode/settings.json would belong there too, if anywhere.

One correction: #93 is about firestore/document/index.ts, which this branch doesn't touch, so I'd take it out of the fix list.

Thanks again for pushing on this.

[KingDarBoja]

Okay, I have made a new branch with a PR for the first step (type fixes): #154