# Plan: Memory and knowledge layering

Audience: demarkus maintainers. Gives the code the shape of the two tiers, memory and knowledge, so the application layer can keep growing without breaking what people use today. Drafted 2026-10-16 with Fritz; proposed, no code. Positioning, the two doors and the transport freeze are settled in [The engine, not the wire](/plans/engine-not-wire.md) and are not repeated here.

## Premise

Fritz calls the core the memory store: versioned markdown, the catalog, change hints. It is well defined. What sits above it is not. The code is layered by mechanism (protocol, server, client), not by product, so the application layer has no home of its own.

| Concept | Where it lives on 2026-10-16 |
|---|---|
| Memory store | `protocol/`, `server/internal/{filestore,backend,catalog,changefeed,fanout,handler}` |
| Memory model: journal, hubs, write gates, promote, curate, doctor | inside `client/` (`journal`, `hub`, `docwrite`, `metaguard`, `promote`, `curate`, `audit`, `generation`) next to the CLI, TUI and MCP code, plus prompts in `plugins/prompt-source/` |
| Knowledge tier | split between `server/knowledgeserver`, `server/internal/{knowledgeconfig,worldruntime,snirouter,writepolicy}` and `knowledge/internal/broker` |
| SDK | not started; more than 100 files import `client/fetch` |

The memory model exists in code but has no name and no module. Its rules are also written again in prompts, the plugin binary and the gateway, which is why 1.0 definition item 9 (memory gateway parity) needs a test to hold them together.

## Target layers

1. **Memory store.** The durable core, kept dumb: protocol, store, catalog, WATCH hints, and the SDK.
2. **Memory model.** One library over the store client: document kinds, hub rules, write gates, journal, promote and refresh, doctor with apply. No MCP, no CLI.
3. **Tiers.** A soul is the model plus local provisioning. A knowledge system is the same model plus worlds, identity and policy. One model, not two applications.
4. **Surfaces.** MCP tools, plugins, the gateway, CLI, TUI and the library stay thin.

Tiers and the durability layers in [the vision](/vision.md) are two axes: tiers say who owns knowledge, layers say how long it must last.

No protocol change. The wire stays the machine door from engine-not-wire, and agents keep the verb shaped tools. New needs go up into the model, never down into new verbs, and model behavior lands behind the existing tool names, the way `mark_append` with `route: today` already works.

## Contracts that must not break

| Contract | Who depends on it | Guard |
|---|---|---|
| Wire protocol | CLI, TUI, MCP server, broker, demarkus-library, Caztor (FETCH only) | storetest; wire fixtures planned in SDK phase 1 |
| MCP tool names, parameters, output | every agent session | plugin eval; no golden test of the tool list found |
| Plugin commands and hooks | plugin users | plugin eval, pre-commit |
| Stored format (`protocol/storefmt`) | every local soul, the GCS deploy | format and fuzz tests |
| Config and token files | deploy repo, installs | `knowledgeconfig` tests; no pinned fixture |
| Go import paths | demarkus-library (`client/fetch`, `mdoutline`, `graphstore`) | its `go.mod` pin |

mark-knowledge imports no demarkus Go code. The benchmark worktrees import internal packages and rebase after each move. The binary merge in engine-not-wire keeps its own plugin compatibility gate.

## Gaps, ranked

1. **Maintenance before features.** This soul has 745 doctor findings and apply is unbuilt ([agent UX](/plans/agent-ux.md) item 3). The root hub holds 47 links against a cap of 40; `/journal/` (127) and `/plans/` (147) have no generated hubs.
2. **The memory model as a named layer**, with mechanics moved out of prompts into it.
3. **The same write gates in both tiers.** The knowledge system refuses secrets at write; this soul holds three `connection-string-password` findings. Check whether the soul write path runs the same content check.
4. **Lifecycle as model rules**: supersede, stale, archive. Overlaps [Embracing staleness](/plans/embracing-staleness.md).
5. **The protocol freeze** after WATCH and ALPN `mark/1` ([ADR 0025](/adr/0025-watch-verb.md)), so the wire stops costing attention.

## Sequence

Each step is additive or behavior neutral.

1. Guards before code: a golden test of the MCP tool list, a config fixture, layer import rules in pre-commit, and the upgrade fixture.
2. Doctor apply and generated hubs, built where the code lives now (`client/audit`).
3. Carve out the memory model, one package per PR, pure moves; proof is identical pre-commit and eval results. `docwrite` splits: write rules toward the SDK, the gate into the model.
4. Move prompt mechanics into the model behind existing tool names, one eval case per mechanic. This retires the Cowork plugin (below).
5. Same gates in both tiers: warn, then refuse.
6. SDK as narrowed in engine-not-wire. Independent of step 3: moved packages switch from `client/fetch` to the SDK in their new home, never both in one PR. The layer guard learns the external module first: the map names the SDK module path as an `sdk` layer that imports nothing, `storeclient` and everything above may import it, `store` may not, so pre-commit rather than review enforces [ADR 0026](/adr/0026-client-sdk-mit-server-never-imports.md). Today the checker drops imports from outside the repo. `storeclient` then means the client helpers that stay in core over the SDK (`listwalk`, `links`, `merge`, `generation`, `joinurl`, `token`, the caches), and the map lines for `fetch`, `listing` and `lookuptable` go once core switches over.
7. Knowledge tier consolidation, decided together with the binary merge.

How each step ships, the engineering bar and the no-friction gate: [Delivery](/plans/memory-knowledge-layering/delivery.md). In short, a pure move or a behavior change, never both, and an upgrade the user does not notice.

## Plugins

[One memory plugin](/plans/memory-knowledge-layering/one-memory-plugin.md): once host reads are MCP tools, `demarkus-cowork` retires and every host runs the same commands; host writes stay shell, hooks stay optional.

## What elegant means

| Principle | Test |
|---|---|
| One model, two tiers | same names, gates and commands in soul and knowledge; promote and refresh are the only edge |
| Mechanics in software, judgment in the agent | prompt source bytes go down; [ADR 0042](/adr/0042-soul-entries-are-agent-written.md) holds |
| Memory maintains itself | zero doctor findings in the classes apply owns; hubs stay under the cap without manual edits |
| Few nouns | nothing beyond memory, soul, knowledge system, world |
| Clean boundaries | dependencies point down only, enforced in pre-commit |
| Thin surfaces | one plugin per host format; the parity test of 1.0 item 9 passes |
| Invisible upgrades | the upgrade fixture passes at every checkpoint |
| Measured | eval pass rate holds; tokens per correct answer go down |

Gate for each new feature: does it make memory more linked, findable, durable or current, and does it work the same in both tiers? If not, it is a product feature, not the model.

## Open questions

- Multi-world hosting: core or knowledge tier? Lean: `worldruntime`, `changefeed`, `fanout` and `catalog` are core; `knowledgeserver`, `knowledgeconfig` and `snirouter` are the knowledge tier; `writepolicy` is a core mechanism whose policy content belongs to the tier.
- The memory model as its own Go module (`memory/`, lockstep versioned) or a directory inside `client/`?
- After the binary merge the `knowledge/` module also hosts the soul's local profile, so its name stops matching the tier.
- Is "memory store" the public word engine-not-wire leaves open?

## Related documents

- [The engine, not the wire](/plans/engine-not-wire.md): positioning, doors, transport freeze
- [Vision](/vision.md): the end state and durability layers
- [Fortify the durable core](/plans/durable-core.md): what the store must keep
- [demarkus-sdk](/plans/demarkus-sdk.md): the client SDK
- [Agent UX](/plans/agent-ux.md): doctor apply
- [Embracing staleness](/plans/embracing-staleness.md): lifecycle
- [demarkus 1.0](/plans/v1.md): item 9, gateway parity
- [Architecture](/architecture.md): module boundaries today