Second Brain system-v1
Contents

Second-brain landscape survey (2026-10-11)

Desk research. Items marked [unverified] came only from secondary or aggregator sources, or could not be confirmed as current.

1. Markdown-native UIs over a vault

  • Obsidian (https://obsidian.md). The app is proprietary freeware: free for any use, but not open source. The data is fully open: plain .md files with YAML frontmatter, and Bases views are stored as .base YAML.
    • Best native iOS and Android apps of anything here.
    • Version 1.12 (Feb 2026) added an official CLI, which needs the desktop app running.
    • obsidian-headless (https://obsidian.md/help/sync/headless) is in open beta. It needs Node 22 and a paid Sync subscription, and lets a server sync the vault with no desktop app.
    • No official MCP server. Community ones wrap the CLI or the Local REST API plugin, or Claude Code can edit the files directly.
  • Obsidian plugins:
    • Bases (core plugin, since 1.9): table, card and list views. Reads frontmatter only, not inline fields.
    • Tasks (MIT): actively maintained; handles recurrence and due dates.
    • Dataview (MIT): effectively frozen. The original author’s last commit was in 2024; only community-maintainer releases since. Its successor, Datacore, is still a work in progress.
    • Kanban (GPL-3.0): last release 2.0.51 about two years ago; “looking for maintainers”.
    • Full Calendar Remastered: a fork claiming two-way CalDAV and Google sync. Young [unverified reliability].
  • SilverBullet (https://silverbullet.md). MIT licensed, self-hosted, stores plain .md files on the server.
    • Mobile is a PWA with an offline IndexedDB cache; no native app.
    • v2 rebuilt it around Space Lua, with built-in tasks and object queries.
    • 2.6 added an experimental Runtime API and CLI. MCP only through community bridges (sb-mcp, silverbullet-ai-mcp).
    • Needs an always-on server.
  • Logseq (https://logseq.com). AGPL-3.0, currently splitting in two.
    • The file-based “OG” version is maintained but gets no new features.
    • The 2.0 DB version has been in beta since 13 Jul 2026. SQLite is the canonical store; an opt-in “Markdown Mirror” writes markdown copies to disk [unverified]. No stable 2.0 release found.
    • Outliner-style markdown is a poor match for a PARA vault. Avoid for a new vault.

2. Open-source task managers

  • Vikunja (https://vikunja.io). AGPL-3.0, REST API and CalDAV; v2.3.0 fixed a 2026 CalDAV CVE. Community-built MCP servers only. Mobile is a PWA; native apps were historically alpha [2026 status unverified]. Stores tasks in a database.
  • Super Productivity (https://super-productivity.com). Open source (license not confirmed).
    • Local-first, plugin API since v14. REST API runs only in the desktop app.
    • Sync via WebDAV, Dropbox or SuperSync. Connects to Google Calendar and CalDAV.
    • Stores JSON, not markdown. Community MCP server from 2025.
  • Taskwarrior 3 / TaskChampion (https://taskwarrior.org). MIT, SQLite replica plus a sync server, strong recurrence.
    • Community MCP server (taskchampion_mcp, 35 tools).
    • iOS apps are Taskchamp and Claw Warrior, both third-party [sync reliability unverified].
  • Plane (https://plane.so). AGPL [unconfirmed], official MCP server (makeplane/plane-mcp-server). A team project-management tool; overkill for personal life.
  • Tasks.md (https://github.com/BaldissaraMatheus/Tasks.md). MIT, self-hosted kanban: lanes are folders, cards are .md files. 3.0 added due dates and picks up changes made outside the app. Deliberately low-maintenance.
  • Markdown storage: only Tasks.md here, plus the inline tasks in Obsidian Tasks and SilverBullet. Every other option means running a second source of truth alongside the vault.

3. Phone capture with no laptop running

  • iOS Shortcuts “Dictate Text” then “Append to File” works in the background without opening Obsidian, but only if the vault is in iCloud Drive. Some users report trouble appending to .md files; test that first.
  • Obsidian URI / Advanced URI actions bring the Obsidian app to the foreground. “Actions for Obsidian” is a proprietary app [not checked].
  • Drafts (proprietary, Pro subscription): the best voice-capture experience; can append to vault files; data ends up as plain markdown.
  • Telegram bot on an always-on server. An n8n template does Telegram voice → Groq Whisper → a commit to GitHub (https://n8n.io/workflows/17896). Groq can be swapped for self-hosted whisper.cpp. Plugin-based bots such as Flowtaker Inbox only work while Obsidian is open.
  • Agent from the phone. Claude Code on the web, reachable from the iOS app, works on a GitHub repo in a cloud sandbox. If the vault is a git repo, the agent can work on it with no laptop on.

4. Agent memory layers

Covered in depth, with what was chosen, in the agent memory research. The layers seen here were Hindsight, Basic Memory, mem0, Letta, Zep / Graphiti and Khoj.

How these tools keep memory from going stale versus the files:

  • Files are the memory (Basic Memory): nothing can drift; the store is only an index of the files.
  • Re-ingest each note by document ID (Hindsight): drift is limited to the sync delay. Whether observations derived from a deleted note are pruned is not documented.
  • Time-stamped invalidation (Graphiti): history is kept, but cleaning up after a deleted note is manual.

5. Existing “AI agent + vault” projects

  • claudesidian (https://github.com/heyitsnoah/claudesidian). MIT, about 2.6k stars. Numbered PARA folders, 14 skills (including inbox-processor and weekly-synthesis), commands such as /daily-review, and git. No task or recurrence handling, no calendar, no memory layer; mobile means SSH over Tailscale.
  • Basic Memory + Claude Code plugin. Briefings at session start and checkpoints before compaction. No tasks or dashboard.
  • Hindsight Obsidian plugin. Chat answers that cite the notes they used. No write-back, no mental models yet.
  • Khoj. Capable, but brings its own UI and server stack.
  • What they got right: the vault is canonical, the agent edits plain files, git makes edits reversible.
  • What every one of them lacks: phone-first capture, recurring tasks with calendar, and an explicit rule for how memory relates to the files.

What this means for the design

  • UI: Obsidian (closed app, open data); SilverBullet as the fully open-source fallback. Tasks in Obsidian Tasks syntax, dashboards in Bases. Don’t depend on Dataview or the original Kanban plugin.
  • Tasks: keep them as markdown in the vault, not in Vikunja or Taskwarrior, which would be a second source of truth. Calendar is the weakest area; plan for read-only ICS, or a CalDAV MCP server for the agent.
  • Sync: choose the sync method first. Plain iCloud allows Shortcuts capture with no infrastructure. Git lets Claude Code cloud sessions reach the vault from the phone. Obsidian Sync with obsidian-headless, or Syncthing, puts the vault on a server for bots and memory sync. Running iCloud and git on the same vault risks conflicts.
  • Memory: decided later, after its own research: plain markdown files in the vault, no memory service (agent memory research).