A private, automated knowledge system

More than notes.
A brain that keeps working.

Second Brain turns the things you save, write, read, and plan into a connected Obsidian knowledge system, with automation doing the repetitive work and you staying in control.

See how the system works ↘
CAPTUREApple NotesSaved articlesGoogle contextAI captures
SBSecond BrainProcess · connect · organise
USEConnected notesTodoist actionsDaily contextSearch & recall

For people who capture a lot, care about what they learn, and are tired of maintaining the system by hand.

Knowledge workersKeep projects, people, decisions, references, and open questions connected.
Builders and researchersTurn scattered reading and working context into durable, source-linked understanding.
Obsidian power usersAdd automation without giving up local Markdown, human edits, or control of the graph.
01 · HOW IT WORKS

Capture once.
Keep compounding.

01

Capture

Bring in selected notes, saved content, calendar context, files, and deliberate AI captures.

02

Filter

Change detection, relevance windows, cursors, and source baselines keep noise and backfill under control.

03

Understand

AI extracts evidence, proposes claims, finds relationships, and drafts targeted updates to the right notes.

04

Validate

Deterministic rules verify evidence, ownership, links, expected state, and safe Markdown before writing.

05

Use

Search the graph, review changes, receive meaningful tasks and digests, and keep the knowledge working.

02 · CAPABILITIES

A complete operating layer for personal knowledge.

Each capability is useful on its own. Together, they turn a folder of notes into a maintained system.

01

Apple Notes ↔ Obsidian

A signed Mac worker keeps selected Apple Notes and Markdown in sync while Apple data stays on the Mac.

02

Connected knowledge

Evidence becomes structured claims, relationships, decisions, tensions, and links instead of another pile of isolated notes.

03

Read-only Google context

Selected Gmail, Drive, and Calendar context can inform the system without granting write authority back to Google.

04

Saved-content synthesis

Saved articles and bookmarks become concise, source-linked notes instead of a backlog you never revisit.

05

Todoist task delivery

Useful next actions are delivered to a dedicated Todoist destination without turning every note into a task.

06

Search and recall

A private index makes the vault searchable from approved tools while the underlying notes remain yours.

07

AI Capture proposals

Raw ideas can become evidence-bound suggestions for existing or new knowledge notes, subject to deterministic checks.

08

Telegram change digest

A compact digest highlights meaningful additions and synthesis without sending full private note bodies.

09

Flexible model routing

The model boundary can move between approved providers while keeping validation and vault authority unchanged.

10

Obsidian Control Panel

Everyday source, output, writing, and style settings live where the knowledge lives: inside Obsidian.

11

Content-free health

Status surfaces report freshness, readiness, drift, and failure classes without publishing note or provider content.

12

Verified backups

Encrypted snapshots and isolated restore checks protect the vault without testing recovery against the live copy.

03 · WHY IT MATTERS

The value is not more notes. It is less cognitive housekeeping.

Remember the useful parts.Important context survives inboxes, tabs, feeds, and fleeting moments of attention.

See connections earlier.New evidence is routed toward the people, projects, ideas, and decisions it can actually change.

Reduce maintenance.Routine collection, organisation, validation, backup, and health checks happen without a manual nightly ritual.

Stay in control.Human edits, local Markdown, explicit approvals, and reversible writes remain more important than model confidence.

04 · ARCHITECTURE

Cloud automation.
Local authority.

MAC

Local knowledge plane

Apple data, the Obsidian vault, signed validation, and final writes stay on the Mac.

  • Apple Notes sync
  • Obsidian vault
  • Deterministic apply
  • Local rollback
N8N

Automation and proposal plane

Private workflows collect non-Apple context, schedule work, call models, and produce bounded proposals.

  • Read-only connectors
  • Model routing
  • Retries and cursors
  • Health and digests
05 · KNOWLEDGE STRUCTURE

Organised by meaning,
not by where it came from.

The system separates raw sources from durable knowledge. New evidence is reconciled against what is already known, then routed to a small set of maintained note roles.

01SOURCESNotes, messages, files, events, saves

Immutable source references preserve where each useful observation came from.

02EVIDENCEClaims, actions, tensions, decisions

Evidence is typed and ranked. Direct human correction always outranks model interpretation.

03KNOWLEDGEMaintained notes and relationships

Only affected notes are drafted, validated, linked, and updated inside their managed regions.

The maintained graph

Roles describe what a note does in the system. Exact paths remain the identity, so similarly named notes in different areas never collapse into one.

PeopleRelationships, commitments, recent developments, and follow-ups.
ThreadsActive projects, decisions, blockers, next actions, and material history.
PositionsSupported beliefs, preferences, principles, and values as they evolve.
DomainsHigh-level navigation, responsibilities, and current priorities.
ReferenceSelected context and dependable source material worth keeping close.
KnowledgeReusable concepts, methods, explanations, and durable understanding.
ConnectionsEvidence-backed patterns, influences, contradictions, and cross-domain links.
LogDated records that preserve chronology without crowding the knowledge graph.
HUMAN-OWNEDYour writing, annotations, and corrections
+
AUTOMATION-MANAGEDA bounded, replaceable synthesis region

Automation can update only its managed region. Everything outside it is verified byte-for-byte before and after a transaction.

06 · MODEL CONTEXT PROTOCOL

A narrow, useful door into the Second Brain.

MCP lets approved AI clients use a small set of Second Brain tools through a standard interface. It is not general access to n8n, the Mac, or the live vault.

search_second_brain

Find relevant knowledge

Searches the private index at a chosen depth, returning ranked results with bounded content only when requested.

READ-ONLY
get_second_brain_note

Read a selected note

Retrieves one exact note after the client has identified it through search. It cannot browse arbitrary files.

READ-ONLY
keep_in_second_brain

Save an explicit capture

Creates one immutable AI Capture only when you clearly ask to keep something. It cannot update or delete existing knowledge.

CREATE-ONLY
AI clientExplicit tool request
→
OAuth-protected MCPIdentity and narrow tool list
→
Fixed private workflowsNo workflow discovery
→
Derived read indexSearch, read, or one capture
WHAT MCP CAN DO
  • Search indexed Markdown
  • Read one exact result
  • Create one explicit AI Capture
  • Return clear, bounded confirmations
WHAT MCP CANNOT DO
  • Discover or execute arbitrary workflows
  • Read credentials or provider configuration
  • Refresh, publish, update, or delete the vault
  • Bypass local validation or human ownership

An AI Capture is not automatically accepted as truth. It first enters a create-only inbox. After it reaches the authoritative local vault, the Mac validates its metadata and may extract supported durable context at lower model-interpretation authority.

07 · BUILT-IN BOUNDARIES

Automation that knows where to stop.

Your notes stay yours

Obsidian remains the authoritative knowledge store. Automation proposes and validates; it does not silently seize ownership.

AI is not the final authority

Models return structured proposals. Deterministic code checks scope, evidence, links, and expected state before anything can change.

No change means no model call

Frequent checks stop early when nothing is new, so freshness does not automatically mean more token usage.

Every plane can fail safely

A connector, model, or synthesis failure preserves the last valid state instead of replacing it with an empty or uncertain result.

08 · ROADMAP

Useful now.
Still getting smarter.

01

Available now

Local Apple Notes sync, Obsidian as the write authority, read-only context collection, connected synthesis, Todoist delivery, private search, health reporting, model routing, Telegram highlights, and verified backups.

02

Improving next

Richer retrieval during synthesis, more consistent cross-source note properties, clearer conflict handling, stronger workflow drift visibility, and deeper owner-controlled writing profiles.

03

Further ahead

A productised Apple Notes Sync app, broader connector packs, safer collaborative review, easier self-hosted installation, and more useful knowledge-health and reflection surfaces.

SB

Your knowledge should become more useful with time, not more work to maintain.

Second Brain is an evolving, self-hosted system for people who want AI-assisted knowledge without surrendering their notes, judgment, or privacy.

Explore the project on GitHub ↗