Edda

Your agent's decisions shouldn't reset every session.
Edda gives coding agents a local, automatic memory of what was decided — and why.
Works with Claude Code, Codex, OpenClaw, and any MCP client.

Why Edda? · Install · Quick Start · How It Works · Comparison · Integration · Architecture

English · 繁體中文

Why Edda?

Yesterday you and your agent argued through the tradeoffs and settled on SQLite. Today's session opens — and it proposes Postgres. Again. The reasoning died with the transcript, and compaction can't bring it back.

Edda fixes exactly this: hooks watch your sessions, capture each decision with its rationale into a local ledger, and hand it to the next session before it starts. The agent stops forgetting.

Without edda                          With edda
────────────                          ─────────
Session 2 opens:                      Session 2 opens:
  "I suggest Postgres for this —        "Continuing with SQLite
   it gives us JSONB and…"               (decided yesterday: single
You: "We settled this. YESTERDAY."       writer, JSONB not needed)…"

You don't need to do anything. After edda init, hooks handle everything:

Data stays local — the ledger lives in .edda/ (SQLite + local files), with no cloud and no accounts. The core loop (record, retrieve, inject) is deterministic and never calls out. Optional LLM assist for session digests, decision extraction, and pattern correlation is opt-in via EDDA_LLM_API_KEY and budget-capped — leave the key unset and edda runs zero-egress.

One memory, every agent

More and more developers alternate between agents — Claude Code for one task, Codex for a second opinion on the next. Both models are strong; what breaks is the memory. Each tool keeps its own silo, so every switch means re-explaining the project from zero.

Edda's ledger is tool-neutral and local. Bridges on each side read and write the same .edda/, so a decision made in one agent is simply there when the other starts:

Claude Code (morning)                Codex (afternoon)
  edda decide "auth=JWT"        →      session opens knowing auth=JWT
          └───────────── one local ledger (.edda/) ─────────────┘

The same wiring covers produce-and-verify workflows: one model writes, the other reviews, and both argue from the same decision history instead of two private ones.

Honest answer: maybe not. If you're one person, one tool, running one
session at a time on a light project, Claude Code's built-in memory is enough.

Edda starts paying for itself when any of these is true:

Install

# One-line install (Linux / macOS)
curl -sSf https://raw.githubusercontent.com/fagemx/edda/main/install.sh | sh

# macOS / Linux (Homebrew)
brew install fagemx/tap/edda

# crates.io
cargo install edda

# Or download a prebuilt binary
# → https://github.com/fagemx/edda/releases

Quick Start

edda init    # auto-detects Claude Code, installs hooks
# Done. Start coding. Edda works in the background.

edda init does three things:

1. Creates .edda/ with an empty ledger
2. Installs lifecycle hooks into .claude/settings.local.json
3. Adds decision-tracking instructions to .claude/CLAUDE.md

The CLAUDE.md section teaches your agent when and how to record decisions:

## Decision Tracking (edda)

When you make an architectural decision, record it:
  edda decide "domain.aspect=value" --reason "why"

Before ending a session, summarize what you did:
  edda note "completed X; decided Y; next: Z" --tag session

This is the key to Edda's automation — the agent learns to call edda decide naturally during conversation, and hooks capture everything else.

How It Works

Claude Code session
        │
   Bridge hooks (deterministic, always on)
        │  ├── record decisions / notes / peer signals
        │  ├── inject prior context on session start
        │  └── optional: doctrine pack from havamal
        ▼
   ┌─────────┐
   │  .edda/  │  ← append-only SQLite ledger
   │  ledger  │  ← hash-chained events
   └─────────┘
        │
   Session end
        │  ├── deterministic digest (always)
        │  └── LLM digest + pattern detection (opt-in, budget-capped)
        ▼
   Next session sees everything

Edda stores every event as a hash-chained JSON record in a local SQLite database. Events include decisions, notes, session digests, and command outputs. The hash chain makes the history tamper-evident and the retrieval deterministic — same query, same answer, no LLM in the loop.

At the start of each session, edda assembles a context snapshot from the ledger and injects it — the agent sees recent decisions, active tasks, peer coordination, and (if configured) a doctrine pack from havamal, without reading through old transcripts.

Where LLM shows up (opt-in only): long-transcript decision extraction, richer session-end digests, and cross-session pattern correlation live in bg_extract / bg_digest / bg_detect. All three are gated on EDDA_LLM_API_KEY plus a daily budget; without the key, edda falls back to deterministic heuristics.

How Edda Compares

| Examples | Claude Code built-in, OpenClaw | mem0, Zep, Chroma | ChatGPT Memory, Copilot | — |

Every ledger query runs locally against SQLite — same answer every time, in milliseconds, at zero cost.

¹ LLM assist is off by default. Set EDDA_LLM_API_KEY to enable session-end digests, decision extraction from long transcripts, and cross-session pattern correlation; each caller has a daily budget cap. The core loop — recording decisions, hash chaining, retrieval, hook-based injection — never calls an LLM.

Integration

Claude Code — fully supported via bridge hooks. Auto-captures decisions, digests sessions, injects context.

edda init    # detects Claude Code, installs hooks automatically

OpenClaw — supported via bridge plugin.

edda bridge openclaw install    # installs global plugin

Havamal (judgment layer) — drop a .havamal-pack.md in your repo and edda auto-injects it as the doctrine section at session start. See havamal — facts flow through edda, judgment enters curated.

Short answer: no — edda is useful on its own. They compose when both are present, but neither depends on the other.

Havamal works standalone with any harness (Claude Code, Codex, Cursor, Gemini CLI) because its contract is a plain markdown file. Edda works standalone because decisions and injection don't need doctrine to function.

Any MCP client (Cursor, Windsurf, etc.) — 7 tools via MCP server:

edda mcp serve    # stdio JSON-RPC 2.0
# Tools: edda_status, edda_note, edda_decide, edda_ask, edda_log, edda_context, edda_draft_inbox

Manual Tools

Most of the time, hooks handle everything automatically. These commands are available when you want to record something manually or look something up:

edda ask "cache"           # query past decisions
edda search query "auth"   # full-text search across transcripts
edda context               # see what the agent sees at session start
edda log --type decision   # filter the event log
edda watch                 # real-time TUI: peers, events, decisions

Architecture

14 Rust crates:

.edda/
├── ledger.db             # SQLite: events, HEAD, branches (append-only, hash-chained)
├── ledger/
│   └── blobs/            # large payloads
├── branches/             # branch metadata
├── drafts/               # pending proposals
├── patterns/             # classification patterns
├── actors.yaml           # roles (lead, reviewer)
├── policy.yaml           # approval rules
└── config.json           # workspace config

Every event follows a hash-chained JSON schema (stored in the local SQLite ledger):

{
  "event_id": "evt_01khj03c1bteqm3ffrv57adtmt",
  "ts": "2026-02-16T01:12:38.187Z",
  "type": "note",
  "branch": "main",
  "parent_hash": "217456ef...",
  "hash": "2dfe06e7...",
  "payload": {
    "role": "user",
    "tags": [],
    "text": "Phase 0 complete: edda in PATH, hooks installed"
  },
  "refs": {}
}

Roadmap

• Prebuilt binaries (macOS, Linux, Windows)
• One-line install script (curl | sh)
• Homebrew tap (brew install fagemx/tap/edda)
• Decision recall metrics
• Cross-project decision search
• tmux-based multi-pane TUI (L3)

Contributing

Contributions welcome. See CONTRIBUTING.md for development setup.

Community

• GitHub Issues — bugs & feature requests
• Releases — changelog & binaries

License

MIT OR Apache-2.0

Stop re-teaching your agent what you already decided.