An agent memory system, to actually be useful, has to do five things: persist information across sessions, give it structure, support retrieval, allow writeback, and handle forgetting.
Most current implementations cover two or three of these. Vector databases nail retrieval but have no structure a human can read. Prompt files like .cursorrules give you persistence and a thin slice of structure but nothing else. Conversation history scrolls past the context window and is gone.
This post walks through the five components and shows how IWE implements each one. No vector database. No proprietary index. The substrate is a directory of markdown files.
The substrate
IWE is a Rust binary that treats a directory of markdown files as a knowledge graph. Links between files are edges. A link on its own line — [Authentication](auth.md) — is an inclusion link, which establishes a parent-child relationship. Notes can have multiple parents. The graph is rebuilt from the files on every change; the files are always the source of truth.
Agents talk to the graph through a CLI (iwe) or an MCP server (iwec). Humans talk to it through their editor — VS Code, Neovim, Zed, Helix — over LSP.
That's the whole architecture. Now the five components.
1. Persistence
Memory lives as .md files in a directory you choose. It survives sessions, restarts, OS reinstalls, and IWE itself — uninstall the binary tomorrow and your memory is still there, readable in any text editor. Git versions it. rsync backs it up. You already know how to operate it.
Compare to a vector DB or a proprietary blob format: if the vendor changes the format, your memory is stranded.
2. Structure
The structure is the graph. Headers define sections. Inclusion links define hierarchy. Reference links define cross-references. The same note can appear under multiple parents — "Performance Optimization" can live under both Frontend and Backend without duplication.
What structured memory needs — entities, facts, decisions, relationships, temporal context — in IWE these are just notes with links. An entity is a note. A decision is a note linked from the project that made it. A relationship is an inclusion link. Temporal context is git log.
This isn't a clever encoding. It's the boring observation that markdown has always been a graph format, and humans have always written in it.
3. Retrieval
IWE exposes the graph through a query language that reads like Mongo's filter syntax but runs against markdown files:
iwe find "authentication" # fuzzy search across titles
iwe find --filter 'status: draft, priority: {$gte: 8}' # frontmatter predicates
iwe find --included-by projects/alpha:0 # everything under alpha's subtree
iwe find --included-by projects/alpha:0 \
--references people/dmytro \
--filter 'status: draft' # compose structure + fields
The filter operators are the ones you already know: $eq, $ne, $in, $gt/$gte/$lt/$lte, $exists, $and, $or, $not. On top of that, four structural anchors walk the graph's two edge types: --includes, --included-by for hierarchy, --references, --referenced-by for cross-references. Stack them to compose multi-edge queries — "drafts under this project that mention this person" is three flags, not a join.
For navigating, retrieve fetches a note plus its descendants to a given depth, tree shows the hierarchy, squash flattens a subtree into one document. Projection (--project title,status), sorting (--sort modified_at:-1), and limits round it out. count gives you an integer instead of results.
Retrieval is deterministic graph traversal, not similarity search. The structure the human wrote is the retrieval signal. When the agent gets wrong context, you trace which link brought it in and fix the graph.
4. Writeback
The agent writes back the same way you do. Create a note, link it in, done. But writeback goes further than append-only — the same query language that drives reads also drives mutations:
iwe update -k meeting-notes --set status=reviewed --set priority=3
iwe update --filter 'status: draft, reviewed: true' \
--set status=published \
--unset draft_notes
update takes a filter or a key, applies --set and --unset to every match, and rewrites the frontmatter in place. The agent can promote a batch of drafts, tag a set of notes, or adjust priorities across a project — the same filter it used to find the notes is the one it uses to change them.
The MCP server exposes the same operations as tools: create, update, extract (split a section into its own note), inline (pull a referenced note back in), attach (link a note under a new parent). extract and inline let the agent refactor memory the same way a developer refactors code — a note that's grown too long gets split, small notes that belong together get inlined into a summary.
This is what separates real memory from RAG: the agent can read, write, query, and restructure. One source of truth, no sync layer.
5. Forgetting
This is the hardest one. IWE now has a first-class delete with the same filter language:
iwe delete --filter 'status: archived'
iwe delete --filter '{type: scratch, modified: {$lt: "2026-01-01"}}'
Delete is reference-aware: inclusion links to removed notes are cleaned up automatically, inline links are flattened to plain text. Nothing dangles. --dry-run previews without writing. Git means nothing is truly lost — deletions are commits you can reverse.
The full forgetting loop: iwe stats surfaces orphan nodes, dead links, and graph density. iwe find --roots shows unlinked documents — candidates for archival. extract and inline let you summarize subtrees into higher-level notes and archive the details. delete prunes what's no longer needed. The agent can run this loop autonomously: find stale notes, summarize, prune, commit.
Not as elegant as automatic temporal decay, but every step is auditable and reversible.
What this buys you
For agent memory specifically, plain markdown files have a property no vector DB can match: the agent and the human read the same bytes. There is no translation layer where the human's mental model can drift from the agent's stored representation. When the agent surfaces a surprising response, you grep the directory and find out why.
The architectural shape — a human-editable instruction layer, a structured memory layer, a graph view both humans and agents share — is showing up in several places right now. IWE is one open-source implementation of it. The binary is on GitHub, on Homebrew, on crates.io. Point an agent at it and try.
