Every past session, subagent, and workflow -- queryable by your agent.

Humans should not browse session history. Agents should query it.

Ask in plain language. The agent writes the query, runs it, answers.

Not a session browser

Most history tools help humans find old chats.

Obelisk is built for agents. It exposes past work as structured data: sessions, messages, tool calls, subagents, workflows, file history, failures, parent chains, and human-approved markdown memories. The agent writes the query, runs it locally, and answers in plain language.

You don't manage history. You ask questions about past work.

Why Obelisk

Session library	Obelisk
Find an old chat	Answer a question about past work
Human browses snippets	Agent writes and runs a query
Search result list	Structured context and reasoning
Sessions as documents	Sessions as queryable memory
Good for recall	Good for investigation

What you can ask

/obelisk 上次 auth bug 最后到底改了哪些文件，为什么这么改
/obelisk 这个文件最近在哪些 sessions 里被反复修改
/obelisk 找出最近失败的 tool calls，它们分别发生在哪些任务里
/obelisk 那个 review workflow 的 subagents 各自结论是什么
/obelisk 我之前有没有试过这个方案，结果为什么放弃了

Anything Claude Code has done before -- sessions, tool calls, subagents, workflows -- becomes structured, queryable memory. Ask in your own words.

Install

npx skills add tommy0103/obelisk

Or manually: copy obelisk/ into your project's .claude/skills/.

Then in any Claude Code session:

/obelisk <your question>

First run builds the index (~5 seconds for 100 sessions). After that it rebuilds incrementally.

Requires

• Node.js 22+ (uses built-in node:sqlite with FTS5)
• Claude Code with skills support.

How it works

You ask a question
  ↓
Agent writes a JS query against the SQLite index
  ↓
Runs it via node runtime.mjs --query <script>
  ↓
Reads the JSON result, answers you in natural language

When a retrieval produces a memory worth keeping, the agent proposes a markdown memory file. After user approval, it registers that file with the narrow runtime.mjs --attune <script> runtime, which exposes only memory mutation helpers such as remember() and forget().

Memory is a synthesis cache, not a replacement for raw sessions. The agent can decide whether to use, ignore, or verify a memory during an answer. Persistent changes still require human approval, but explicit corrections count: if you say a memory is wrong, outdated, or should be replaced, the agent can archive or update the exact matching record without a second confirmation.

The core idea: don't make humans browse, tag, or organize sessions. Don't invent a rigid query DSL either.

Agents can write code. So Obelisk gives them a small local query runtime over your past work.

The agent starts from a small core API, then uses structured shortcuts and references only when the question needs them:

Core primitives — the main CodeAct surface:

• search(text) — FTS5 full-text search, returns matches with surrounding context plus message content_type and is_meta
• context(uuid) — full story around a message (parent chain, subagent/workflow metadata)
• sql(query, ...params) — read-only SQL for structured queries

Structured shortcuts — overview, session, memory, summary, subagent, workflow, file-history, failure, raw-window, and parent-chain helpers over the same SQLite data.

References — agent reads on demand when the task needs deeper structure:

• references/schema.md — full SQLite schema and API reference
• references/query-patterns.md — copyable CodeAct recipes for common retrieval tasks
• references/retrieval-semantics.md — query design frame for scoped and synthesis retrieval
• references/recap/overview.md — optional /obelisk recap card-by-card entrypoint
• references/recap/pattern1-cover.md and references/recap/writing1-cover.md
• references/recap/pattern2-thinking.md and references/recap/writing2-thinking.md
• references/recap/pattern3-vibe.md and references/recap/writing3-vibe.md
• references/recap/pattern4-workflow.md and references/recap/writing4-workflow.md
• references/recap/pattern5-closing.md and references/recap/writing5-closing.md
• references/pitfalls.md — scope, FTS, ordering, compact/raw, and field-name traps

The executable SQLite schema lives in scripts/schema.sql; references/schema.md is the human/agent explanation of that contract.

The design is progressive disclosure with guardrails: the main skill keeps the core contract and high-risk pitfalls visible, while longer recipes and the full schema stay out of the first prompt until the agent needs them. The optional recap references are only for the explicit /obelisk recap intent; they are not part of the ordinary retrieval path. references/recap/overview.md drives a card-by-card loop: read one card's retrieval pattern, gather that card's evidence, read its writing reference, update the JSON, then continue. This keeps schema, taste, and query planning from competing in one large prompt.

What gets indexed

Layer	Source	What's captured
Sessions	<project>/<sessionId>.jsonl	Title, project, timestamps, git branch
Messages	user + assistant turns	Full text, model, token usage, parent chain
Tool calls	every tool invocation	Tool name, input, file paths touched
Subagents	subagents/agent-<id>.jsonl	Agent type, description, full conversation
Workflows	workflows/wf_<runId>.json	Script, structured result, agent count
Workflow agents	subagents/workflows/wf_<runId>/	Per-agent transcripts linked to workflow
Memories	markdown files registered by the agent after user approval	Prior conclusions linked to source sessions/messages and optional anchors

Full-text search via FTS5 covers message text across every session layer and ranked memory recall over registered memory summaries, while the SQLite tables preserve the structure agents need for investigation.

Structure

.claude/skills/obelisk/
├── SKILL.md              # Skill definition + simple API + examples
├── scripts/
│   ├── schema.sql        # Executable SQLite schema
│   └── runtime.mjs       # Indexer + query runtime (zero deps)
└── references/
    ├── schema.md          # Full table schema + advanced API reference
    ├── query-patterns.md  # Copyable retrieval recipes
    ├── retrieval-semantics.md # Query design frame for retrieval semantics
    ├── recap-patterns.md  # Compatibility pointer to references/recap/overview.md
    ├── recap-writing.md   # Compatibility pointer to per-card recap writing docs
    ├── recap/
    │   ├── overview.md
    │   ├── pattern1-cover.md
    │   ├── writing1-cover.md
    │   ├── pattern2-thinking.md
    │   ├── writing2-thinking.md
    │   ├── pattern3-vibe.md
    │   ├── writing3-vibe.md
    │   ├── pattern4-workflow.md
    │   ├── writing4-workflow.md
    │   ├── pattern5-closing.md
    │   └── writing5-closing.md
    └── pitfalls.md        # Scope, FTS, ordering, and compactness traps

Implementation Notes

The index rebuilds incrementally — only new or modified JSONL files are re-parsed. When the optional app is running, it is the active indexer: it watches Claude project files, builds in a worker thread, writes __app_heartbeat__ plus __app_last_successful_build__ into index_state, and the skill-side lazy build skips work only while both markers are fresh.

Zero npm dependencies. Uses Node 22's built-in node:sqlite with FTS5. The entire runtime is ~400 lines.

20K lines of scattered JSONL → something the agent can search() and sql() against in milliseconds.

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License

MIT @tommy0103