# RFC 002 — The joiner: replaying a second palace into the shared primary

**Status:** scoping. No code written yet.
**Author:** pi (agent), 2026-08-15.
**Context:** RFC 001 §4.4 designs a join as "idempotent replay of local history" but no replay tool
exists. The first two joins were whole-palace *file copies* (§4.4 deviation note), which work only for a
single source and cannot merge. tor-ms22 and MBP-M1-2020 each hold a substantial local palace whose
content should reach the primary. This document scopes the tool that does that.

> **Every mechanism below was read out of mempalace 3.6.0's own source** at
> `/opt/uv-tools/mempalace/lib/python3.13/site-packages/mempalace/`, with file:line in the appendix.
> An earlier attempt to gather these facts via a delegated subagent returned confident, fabricated code
> for a package path that does not exist on this machine. **Do not trust any claim in this document that
> the appendix does not cite.**

---

## 1. The finding that drives the design

**MCP replay cannot preserve `filed_at`.** `add_drawer` stamps
`"filed_at": datetime.now().isoformat()` server-side (`mcp_server.py:2580`) and exposes no override
parameter. `diary_write` is the same: it builds its own `now`-based id (`mcp_server.py:3510-3513`).

That is not a detail. This palace's value *is* its chronology — the primary's history runs from
2026-05-04, `list_drawers` filters on `since`/`before` against `filed_at`, and the diary is read in
order. A pure MCP replay of tor-ms22's palace would stamp **every** record with the join date,
collapsing months of history into one instant. RFC 001 §4.4 does not mention this, and it is the single
most important thing to decide before writing code.

`kg_add` is the exception: it accepts `valid_from`/`valid_to`, so **fact validity windows survive** even
though a triple's own id embeds `recorded_at`.

### Two write regimes

| | **A — direct disk write** (run on synlig) | **B — MCP replay** (run anywhere) |
| --- | --- | --- |
| Preserves `filed_at` / original ids | **Yes** — `col.add(ids=…, documents=…, metadatas=…)` | **No** — always `now()` |
| Server-side dedup guards | **Bypassed** — joiner owns all dedup | **Available** (see §2) |
| Requires quiescing `mempalace-serve` | Yes (palace is single-writer) | No |
| Requires source palace present on synlig | Yes (rsync it first) | No |
| Precedent in-tree | **`migrate.py`** already does exactly this: reads drawers+metadata straight from the palace's sqlite, then re-adds them into a fresh palace preserving ids, documents and metadata (`migrate.py:326-330`) | none |

**Recommendation:** regime **A** for the historical bulk (it is the only one that keeps the timeline, and
`migrate.py` is a working model to copy), regime **B** for small incremental top-ups where flattened
timestamps are acceptable. Do not build B first and discover the chronology loss afterwards.

---

## 2. What must move, and what dedupes it

Verified dedup keys — this supersedes nothing in RFC 001 §4.4 but makes each key concrete:

| Class | How to identify it in the source palace | Dedup key (verified) | Regime A work | Regime B work |
| --- | --- | --- | --- | --- |
| **Agent-authored drawers** (`add_drawer`/`checkpoint`) | `source_file` empty | id is `sha256("{wing}\|{room}\|{content}")[:24]` (`ids.py:80`, used at `mcp_server.py:2560`) — **fully content-deterministic** | recompute id, skip if present | none: server probes `[drawer_id, last_chunk_id]` and returns `{"success": True, "reason": "already_exists"}` (`mcp_server.py:2593-2604`) |
| **Mined drawers** | `source_file` set | id is `sha256("{source_file}\|{chunk_index}")[:24]` (`ids.py:67`) — **path-dependent**, so the same content from two machines yields two rows | — | **do not replay.** Re-mine on synlig instead (§4) |
| **Diary entries** | id prefix `diary_`, `room="diary"` | id is `diary_{wing}_{now:%Y%m%d_%H%M%S%f}_{sha256(entry)[:12]}` (`mcp_server.py:3510-3513`). Timestamp is wall-clock, so **full ids never repeat** — match on the 12-hex suffix only | copy row verbatim (id and all) | build the target's suffix set, skip matches — this is RFC 001 §7.6 |
| **KG open facts** (`valid_to IS NULL`) | `triples.valid_to IS NULL` | server guard `WHERE subject=? AND predicate=? AND object=? AND valid_to IS NULL` returns the existing id (`knowledge_graph.py:305-311`) | pre-query same key | none: just replay |
| **KG closed facts** (`valid_to` set) | `triples.valid_to IS NOT NULL` | **no server guard at all** — the guard above is scoped to open facts, so every replay inserts a fresh row | pre-query `(s,p,o,valid_from,valid_to)` | same pre-query, client-side |
| **Entities** | `entities` table | — | needed as FK targets for triples | `kg_add` creates them implicitly |

Chunking is deterministic and replay-safe: `DEFAULT_CHUNK_SIZE = 800` (`config.py:274`), chunk ids are
`f"{drawer_id}_chunk_{i:06d}"`, so nothing about chunking needs special handling.

### Not carried by either regime

**Hallways, `known_entities.json`, and the palace graph are built at mine time**, not by `add_drawer`.
Replayed drawers therefore arrive with no hallway/co-occurrence edges, so `list_hallways` and `traverse`
will under-report for joined content. These are derived artifacts — rebuildable by re-mining, or
acceptably degraded. Decide which; do not discover it later. (`hallways.py`, `entities.py`,
`palace_graph.py` — none referenced from the `add_drawer` write path.)

---

## 3. Phases and deliverables

**Phase A — census (read-only, no writes anywhere).** Point a script at a palace on disk, enumerate every
parent drawer from `chroma.sqlite3` (`embeddings` ⋈ `embedding_metadata`) plus every row of
`knowledge_graph.sqlite3`, classify each into the §2 rows, and emit a manifest JSON + counts.
*Deliverable: "tor-ms22 holds N agent-authored drawers, M diary entries, K closed facts, and X mined
drawers we will re-mine instead."* This is the number that sizes everything else, and it is the piece to
run the moment tor-ms22 is reachable. **Build this first and independently** — it is useful even if the
writer is never written, and it cannot break anything.

**Phase B — target index.** Given the primary, build the three lookup sets Phase C needs: content-drawer
ids, diary `sha256(entry)[:12]` suffixes, and `(s,p,o,valid_from,valid_to)` tuples. Over MCP this is
`list_drawers` pagination + `kg_timeline`; on synlig it is two sqlite queries. Cheap either way.

**Phase C — writer**, with `--dry-run` as the default and an explicit `--apply`, mirroring `sync`'s
contract. Two backends behind one interface:
- `--mode direct` (regime A): stop `mempalace-serve`, `col.add()` with original ids/metadata, restart.
  Model on `migrate.py`. Must refuse to run if the server is up.
- `--mode mcp` (regime B): `add_drawer`/`diary_write`/`kg_add` over HTTP, accepting `filed_at` loss.

**Phase D — verification.** Counts before/after per class, a real `search` against known joined content
(proves the HNSW index absorbed it — this is how the first seed was verified), `kg_stats`, and a spot
`get_drawer` on a known id. Plus: re-run the Phase A census against the *target* and diff.

---

## 4. Explicitly out of scope

- **Mined wings.** RFC 001 §5 makes them `local`; their ids are path-dependent, so replay produces
  duplicates rather than dedup. Re-mine on synlig from sources present there. This is also the bulk by
  count — on the primary, only **438 of 14,829** drawers have no `source_file`, so the genuinely
  replay-only surface is hundreds, not tens of thousands.
- **Merging two palaces into a third.** Every join targets the existing primary.
- **`mempalace sync` interaction.** See RFC 001 §7.2 — settle the guard separately; a joiner must never
  call it.

## 5. Open decisions for ALC

1. **Chronology: keep it or flatten it?** Regime A keeps it and costs a service stop plus an rsync of the
   source palace onto synlig. Regime B is simpler and loses it. This is the fork in the road.
2. **Hallways for joined content:** re-mine to rebuild, or accept degraded `traverse`?
3. **Do MBP-M1-2020 and tor-ms22 keep their palaces on persistent storage?** If either is a Docker named
   volume rather than a bind mount, its un-migrated content dies on the next container recreate — so the
   census (Phase A) is time-sensitive there, and flipping before censusing is risky.
4. **Does §7.6 get fixed client-side (in the joiner) or upstream (probe-and-skip in `diary_write`)?** The
   joiner needs the suffix skip either way; upstream would fix it for every writer.

## 6. Effort

Phase A is the bulk of the value and is small — two sqlite readers and a classifier. Phase B is trivial.
Phase C is where the risk lives, and regime A must be written defensively (refuse on a live server,
back up first, `--dry-run` default). Phase D is mostly assertions. Nothing here needs new server code,
which is the point of RFC 001 §4.4's "existence checks available today".

---

## Appendix — verified source references

mempalace 3.6.0, `/opt/uv-tools/mempalace/lib/python3.13/site-packages/mempalace/`:

| Claim | Location |
| --- | --- |
| Content-addressed drawer id, 24 hex over `wing\|room\|content` | `ids.py:80` (`make_drawer_id_from_content`), `_HASH_TRUNC_DRAWER = 24` at `ids.py:36` |
| MCP `add_drawer` uses that recipe | `mcp_server.py:2560` |
| Miner id over `source_file\|chunk_index` | `ids.py:67` (`make_drawer_id_from_chunk`), used `miner.py:1381`, `format_miner.py:645` |
| Idempotency probe + `already_exists` (probes parent **and** last chunk) | `mcp_server.py:2593-2604` |
| `filed_at` stamped server-side, no override | `mcp_server.py:2580` |
| Diary id recipe, suffix = `sha256(entry)[:12]` | `mcp_server.py:3510-3513` |
| Triple id `t_{s}_{p}_{o}_{sha256(valid_from\|recorded_at)[:12]}` | `ids.py:111-131`, `_HASH_TRUNC_TRIPLE = 12` at `ids.py:37` |
| `add_triple` guard scoped to open facts | `knowledge_graph.py:305-311` |
| Chunk size 800 | `config.py:274` |
| Direct-write precedent preserving ids+metadata | `migrate.py:326-330` |
| No join/replay/import tooling exists | `cli.py` subcommands; `exporter.py` emits markdown (lossy, not a join primitive); `diary_ingest.py` ingests *daily-summary files*, unrelated to agent diaries; `migrate.py` is single-palace chromadb recovery; `dedup.py` is cosine-similarity pruning within one `source_file` |