How do you manage research for multiple client projects without losing your mind?

Freelancing for 6 different clients currently. Each has their own industry, brand voice, style guide, and ongoing projects.

The chaos:

Client A prefers AP style, Client B uses Chicago, Client C doesn't care but hates Oxford commas

Brand guidelines scattered across emails, Google Docs, PDFs, Slack messages

Research for articles saved in random folders I can never find later

Interview transcripts from 3 months ago that I need to reference but can't locate

My current broken system:

Google Drive folders per client (theoretically organized, actually a mess)

Evernote for research (stopped using it consistently)

Browser bookmarks (hundreds of them, none tagged properly)

"I'll remember where I saved this" (narrator: she did not remember)

Real example from last week:

Client asked me to reference their Q2 strategy doc in new article. Spent 45 minutes searching emails trying to find it. Finally asked them to resend it. Felt unprofessional.

What I'm trying:

Started using Nbot Ai to upload all client docs so I can search across everything when I inevitably forget where something is

Using Perplexity for research instead of getting lost in Google rabbit holes

Claude for checking if my drafts match client voice (not writing them, just checking consistency)

Questions for other freelance writers:

How do you organize client information across multiple projects?

What's your research workflow that doesn't result in 50 open tabs?

How do you quickly find that one thing a client told you 2 months ago?

Any tools that actually help versus just adding more places to lose information?

What I need:

System that doesn't require perfect discipline to maintain (because I don't have that)

Way to find client requirements quickly without searching 6 different places

Research organization that survives past the initial enthusiasm phase

Currently considering just... getting better at organization? But that hasn't worked for 3 years so probably need actual tools.

What works for you?