obsidian-second-brain turns an Obsidian vault into persistent, searchable memory for Claude Code and other command-line coding agents, storing knowledge as linked Markdown notes. It is for developers, founders, writers, and researchers who want agents to retain project context across sessions. Its catalogue entries provide commands, hooks, a plugin, a skill, and instructions for capturing, finding, and maintaining that memory.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
git clone --depth 1 https://github.com/eugeniughelbur/obsidian-second-brainWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/commands/eugeniughelbur/obsidian-second-brain/obsidian-learn)<a href="https://agentmods.dev/commands/eugeniughelbur/obsidian-second-brain/obsidian-learn"><img src="https://agentmods.dev/badge/commands/eugeniughelbur/obsidian-second-brain/obsidian-learn/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/commands/eugeniughelbur/obsidian-second-brain/obsidian-learn"><img src="https://agentmods.dev/badge/commands/eugeniughelbur/obsidian-second-brain/obsidian-learn.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00020 | $0.01179 |
| Opus 5 | $0.00010 | $0.00589 |
| Sonnet 5 | $0.00004 | $0.00236 |
| Haiku 4.5 | $0.00002 | $0.00118 |
Grade A, and why
obsidian-learn scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 66 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Use the obsidian-second-brain skill. Execute /obsidian-learn $ARGUMENTS:
The optional argument is a scope: recent (last 30 days, default), all (entire vault), or a topic name. Scope limits the review LIST only - the Stale and Superseded classifications always scan the entire vault, since a 6-months-old learning cannot appear inside a 30-day window.
-
Read
_CLAUDE.mdfirst if it exists in the vault root -
Read
index.mdand recent operation log for vault context (ifLogs/exists: read the last 2-3Logs/YYYY-MM-DD.mdfiles; otherwise readlog.md) -
Spawn parallel subagents to gather learnings:
- Lessons agent: scan all daily notes for "Lesson learned" sections, "What didn't" sections, evening review insights
- Decisions agent: read all ADRs in the decisions folder (resolved per
references/folder-map.md- wiki-stylewiki/decisions/, Obsidian-styleKnowledge/withADR-filename prefix) - extract the rationale and outcome of each - Reports agent: read recent emerge/synthesize/connect/challenge reports in the concepts folder (resolved per
references/folder-map.md) - the auto-generated pattern reports - Mistakes agent: scan dev logs and daily notes for "what didn't work", "wasted time on", "next time", "lesson", phrases indicating learning from failure
- Wins agent: scan for patterns that worked - "this saved time", "this approach worked", recurring success patterns
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For each learning found, classify:
- Active: still relevant, recurring, reinforced by recent activity
- Stale: 6+ months old with no recent reinforcement, or contradicted by newer evidence
- Superseded: explicitly replaced by a newer ADR or pattern
- Promoted: appeared 3+ times - should become a permanent rule in
_CLAUDE.md
-
Generate the Learnings Report:
Active Learnings (still applies)
- List learnings reinforced in the last 90 days
- Cite the original source and most recent reinforcement
Stale Learnings (consider archiving)
- List learnings with no recent reinforcement
- Suggest: keep, archive, or convert to history note
Superseded Learnings (already replaced)
- Old position → New position with ADR reference
Promotion Candidates (appeared 3+ times)
- Learnings strong enough to become permanent rules in
_CLAUDE.md - Suggest exact wording for the operating manual
Top 5 Lessons of the Period
- Most impactful learnings ranked by frequency × recency × consequence
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Save the report to the concepts folder (resolved per
references/folder-map.md) asYYYY-MM-DD - Learnings Review.md(type: learnings-review, schema inreferences/ai-first-rules.md) -
Append to the operation log: if
Logs/exists write**HH:MM** - learn | X active, Y stale, Z superseded, N promotion candidatestoLogs/YYYY-MM-DD.md; otherwise append## [YYYY-MM-DD] learn | X active, Y stale, Z superseded, N promotion candidatestolog.md -
Update today's daily note with a brief summary
-
Offer to:
- Promote candidates to
_CLAUDE.md(with user confirmation) - Archive stale learnings (with user confirmation)
- Export top 5 as a shareable markdown for content/journaling
- Promote candidates to
Lessons that aren't reviewed don't compound. This command turns scattered notes into a living rulebook.
AI-first rule: Every note created or updated by this command MUST follow references/ai-first-rules.md - ## For future agent preamble, rich frontmatter (type, date, tags, ai-first: true, plus type-specific fields), recency markers per external claim, mandatory [[wikilinks]] for every person/project/concept referenced, sources preserved verbatim with URLs inline, and confidence levels where applicable. If that path does not resolve from your working directory, search upward for it; if you still cannot read it, say so before writing rather than producing a note that silently skips the rule. The vault is for future agent retrieval - not human reading.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 9d ago First seen · 66 lines · 20 tokens per session scan A 5d5667d039ac
obsidian-learn is a command published in the GitHub repository eugeniughelbur/obsidian-second-brain (4,364 stars, last pushed 2d ago), licensed MIT. It adds 20 tokens to every session and 1,179 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
Other commands, from other repositories
patterns
Scan recent sessions for recurring patterns and turn them into captures (rules, concept notes, writing seeds).
second-brain-mapping
Map your vault: extract structured metadata from every typed file, surface cross-doc insights, optionally build a knowledge graph.
cierre
A sales call just ended: turn its transcript into the full follow-up (CRM, tasks, email draft, reminder, coaching).
daily-journal
Daily journal interview and entry creator with emotional floor tagging.
deconstruct
First-principles analyst: surface hidden assumptions, find foundational truths, rebuild from scratch.
diagnose
Run a self-check on your AI Brain Starter install (CLAUDE.md, Meta folder, skills, hooks, MCPs).