Before any prompt goes into Stitch, AI Studio, or your code editor, this is the paperwork that needs to exist first. Skipping this is how you end up with an AI that “vibes” its way into a half-built screen, forgets why a button exists, or rebuilds the same auth flow three times because there was no spec to point back to.

Why Do You Need To Document Your Product Idea In detail?

When you vibe code without docs, the AI is improvising from your last message only. It has no memory of the decision you made two days ago about whether usernames are unique or whether comments are nested. Every session becomes a re-negotiation.

Create A Product Requirements Document 

• Problem statement : what’s broken or missing right now, stated plainly. Not “users want a better experience,” but the actual pain.
• Target users : who specifically. For your apps this might be “Gen-Z Indian micro-fiction writers who post on Instagram but want a dedicated space” : specific enough that a feature decision later has an obvious answer.
• Core features : the list, prioritized. Mark what’s v1 vs. v2 so the AI (and you) don’t scope-creep the first build.
• Success criteria : measurable. Not “users like it” but “user can post a 100-word story and get a reaction within 10 seconds of opening the app,” or “DAU retention >30% at day 7.” If you can’t measure it, it’s not a success criterion, it’s a vibe.

Why it matters for your workflow specifically: every Stitch/AI Studio prompt you write later should trace back to a line in this doc. If a feature request doesn’t map to anything in the PRD, that’s your signal to either update the PRD deliberately or say no to the feature.

 TRD : Technical Requirements Document

What goes in it:

• Framework : for you, this is your Android stack: Kotlin/Compose (or whatever Stitch is outputting), Firebase as backend.
• UI approach : Stitch-generated screens, your retro pop-funk design system, component conventions.
• API gateway / backend structure : Firebase Functions if you’re using them, REST conventions, how the app talks to Firebase.
• Database : Firestore (your case) vs. Postgres/Redis if you ever go server-side for something heavier. State explicitly why Firestore over a relational DB for this project : usually it’s “fast to ship, real-time sync, fits Firebase Auth” but write it down so future-you doesn’t second-guess it mid-build.
• Auth & security baseline : Firebase Auth, App Check, the rate-limiting approach you’ve been learning. This is the doc where Firestore Security Rules get referenced, not written (that’s almost its own appendix, but link it here).
• Third-party services : anything else: image hosting, push notifications, analytics.

User Journey Document (you called this “app flow”)

What goes in it:

• Every screen in the app, roughly sketched (doesn’t need to be pixel-perfect : that’s design.md’s job).
• The path between screens: onboarding → home feed → post creation → comment → profile, etc.
• Branch points: what happens on error, on empty state, on first-time-user vs. returning-user.

Design.md : Design System Document

What goes in it:

• Typography : font family, weight scale, sizes for headers/body/captions.
• Color palette : your established bold retro Memphis / neo-brutalist palette: bright accent colors, what’s primary vs. secondary, background tones.
• Visual language : thick outlines, hard shadows, diagonal hatching : the stuff that makes your stuff recognizably yours instead of generic Material Design. Write down pixel values for shadow offset/blur if you have them, so Stitch outputs stay consistent screen to screen.
• Component conventions : button shapes, corner radius (or lack of it, if you’re going hard-edged neo-brutalist), spacing units.

Schema.md : Database Schema Document

What goes in it:

• Every collection/table, every field, every type.
• Relationships : what references what (e.g., a post document holds a userId reference, a comments subcollection sits under each post).
• For Firestore specifically: note your collection structure (top-level vs. subcollections), since that decision is expensive to change later and directly shapes your Security Rules.
• Indexes you know you’ll need (anything you’ll query/filter/sort by).

Implementation Document

What goes in it:

• Build order : literally, what gets built first, second, third. Usually: auth → core data model → primary screen/feed → secondary features → polish.
• Dependencies : what has to exist before what (e.g., can’t build the comment feature until posts exist and auth is wired).
• Milestones : natural checkpoint groupings, not necessarily tied to calendar dates.

Why it matters for AI-assisted building specifically: this is the doc that stops you from asking the AI to build the profile screen before auth even exists. It’s your build sequence, written down so each session picks up exactly where the last one left off instead of you re-deciding priority every time you open the laptop.

Tracker.md : Progress Tracker

What goes in it:

• A simple status table: feature/screen → status (not started / in progress / done / blocked) → notes.
• Update this every session, even briefly. It’s the single fastest way to re-orient yourself (or hand context to an AI) after a few days away from the project.

Format that works well:

Item	Status	Notes
Firebase Auth setup	Done	Email + Google sign-in
Firestore schema (posts, users)	Done	See schema.md v2
Feed screen (Stitch)	In progress	Pagination not wired yet
Comment system	Not started	Blocked on feed screen
Rate limiting	Not started	Needs App Check first

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Rules.md : Rules Document

What goes in it:

• Coding conventions: naming, file structure, comment style.
• AI-behavior rules specifically for vibe coding sessions: things like “don’t modify schema.md without flagging it,” “always check tracker.md before starting a new feature,” “ask before introducing a new dependency.”
• Security non-negotiables: e.g., “never write Firestore rules that default to allow,” “API keys never hardcoded, always env vars.”

Why this is last but not least: this is the doc you paste into the system prompt or top of every coding session. It’s the guardrail that keeps an enthusiastic AI from “helpfully” refactoring something you didn’t ask it to touch, or quietly loosening a security rule to make a feature work.

How these eight feed each other (the actual sequence)

PRD (what & why)

  → TRD (with what tools)

    → User Journey (what screens, what order)

      → design.md (what it looks like)

        → schema.md (what the data looks like)

          → Implementation doc (build order)

            → tracker.md (live status, updated continuously)

rules.md sits alongside all of them : referenced in every session, not a one-time read.

Practical habit: keep all eight as actual files in your project repo (or a dedicated Drive folder), not just chat history with Claude/Stitch. The whole point is they outlive any single chat session.