# Synthesis — the shard spectrum: one capability model across the full dive set

Date: 2026-06-14 · **revised 2026-06-14 (v3)** — extended from the fourteen-system set to
include the **SHARD-WP-0003 engine batch** (Federated Wiki, Wikibase/Wikidata, the git-forge
wikis Gitea/GitLab/GitHub, TiddlyWiki, ikiwiki, Salesforce Quip, MojoMojo, Oddmuse,
UseModWiki). Per-shard spectra grown from thirteen to **fourteen** (added **provenance
granularity**), with refinements to merge-model, attachment-mode, native-query, structure,
history, content-opacity and write-granularity; and a **new coordination-layer axis — the
federation-model taxonomy (§2.5)** — the headline v3 contribution.
Source kind: **synthesis** — consolidates every deep dive into a single comparative model
feeding the **shard adapter contract** and the **federation track** (`SHARD-WP-0002`).
Lens: shard-wiki — what a backend must expose to participate, expressed as *spectra* of
capability rather than a yes/no checklist.

> Purpose. ~23 tools/systems have now been studied. Two conceptual ancestors (**Xanadu,
> ZigZag**); the file/DB engines (**XWiki, TWiki, Foswiki**, + landscape); the modern
> note/PKB tools (**Roam, Obsidian, Notion, Joplin, Logseq, Anytype, AFFiNE, AppFlowy,
> Trilium**); and the WP-0003 batch (**Federated Wiki, Wikibase, forge wikis, TiddlyWiki,
> ikiwiki, Quip, MojoMojo, Oddmuse, UseModWiki**), against the federation and origin
> research. This document reads them *across* each other. The payoff is a small set of
> **capability spectra** — now **fourteen** per-shard, plus a **federation-model taxonomy**
> for the coordination layer — each anchored at both ends by a real system, with federation
> operations degrading by position. That spectrum *is* the adapter contract's design
> surface. v3 folds the WP-0003 use cases (**UC-68–UC-82**) into the `SHARD-WP-0002` tasks.

Inputs: `research/260608-{federation-concepts,wikiengines-overview,c2-wiki-origins,yawex-prior-art}`,
`research/260613-{xwiki,twiki,foswiki}-deep-dive`,
`research/260614-{xanadu,zigzag,roam,obsidian,notion,joplin,logseq,localfirst-workspaces,trilium,wikijs,federated-wiki,wikibase,forge-wikis,tiddlywiki,ikiwiki,quip,mojomojo,oddmuse,usemodwiki}-deep-dive`.
Output target: `spec/TechnicalSpecificationDocument.md` (adapter contract) via
`SHARD-WP-0002`.

---

## 1. The shard family matrix

Candidate-shard backends across the dimensions that matter to the contract. (Xanadu and
ZigZag are *not* shards — they are the conceptual ideals each column aspires to; Federated
Wiki is *barely* a shard — it is mostly a **federation model**, see §2.5; both listed apart.)

| Backend | Substrate | Attach mode(s) | Addressing | Structure | History | Merge | Query | →Markdown | Opacity |
|---------|-----------|----------------|-----------|-----------|---------|-------|-------|-----------|---------|
| **Git folder / forge wiki** | files (`.wiki.git`) | **file-store (git IS store)** | path (+ commit) | flat MD + frontmatter | **git-native** | git/text | no | native | none |
| **ikiwiki** | files (git) → static HTML | file-store (source repo) | path | flat MD + directives | **git-native** | git/text | no | native (src) | none |
| **Obsidian** | files | file-store **/** plugin | path + in-file `^id` | frontmatter (in-file) | none (Git plugin) | git/text | plugin (Dataview) | native (OFM) | none |
| **Logseq** | files (MD/Org) → SQLite | file-store **/** plugin | **in-file block `id::`** (sweet spot) | `key::` props (in-file) | none (git) | git/text | **Datalog (derived)** | native-ish | none |
| **TiddlyWiki** | single HTML **/** `.tid` dir | **file-store (container/`.tid`)** | tiddler `title` | typed tiddler **fields** | none / git (.tid) | git/text | **filters** | varies (`type`) | none |
| **TWiki / Foswiki** | files + RCS / pluggable | file-store **/** API | path | `%META%` in-file (N records) | **open file (RCS)** | git/text | no | lossless (TML) | none |
| **Oddmuse / UseModWiki** | flat files (CGI) | file-store (**minimal floor**) | CamelCase/path | none (flat) | flat-file, **partial** | last-writer | no | lossy | none |
| **MojoMojo** | relational DB | **direct-DB-read** | page row / path | relational rows+lineage | **DB version rows** | last-writer | SQL | MD-in-column | none |
| **Trilium** | SQLite (one file) | ETAPI / scripting / DB | `noteId` + **`branchId`** (id≠place) | labels+relations, **inherited+templated**; **DAG** | internal revisions | conflict-res | attr search | **lossy (HTML)** | **per-note** |
| **Joplin** | SQLite-local | **sync-mirror** / local-REST / plugin | page-level `:/id` | notebooks + tags | internal revisions | conflict-notes | search | lossy | E2EE (whole) |
| **Wiki.js** | DB ↔ git mirror | file-store(mirror) / **GraphQL** | path | frontmatter (mirror) | git (via mirror) | git/text | GraphQL | native (mirror) | none |
| **XWiki** | DB (Hibernate) | in-engine host / REST | path | **XObjects/XClass** | internal (`xwikircs`) | git/text | yes (XWQL) | engine syntax | none |
| **Quip** | hosted (SaaS) | **external-API (HTML)** | doc id + section anchor | **prose + inline spreadsheets/live-apps** | internal | server (OT) | no | **lossy (HTML)** | proprietary |
| **Roam** | client DataScript | **in-app host only** | **store UUID** | `key::` attrs | internal (txn log) | (in-app) | yes (Datalog) | (Roam MD) | none |
| **Notion** | hosted Postgres | **external-API (block-JSON)** | store UUID | **DB schema + relations + rollups** | internal, not portable | internal | yes (DB query) | **lossy** | none |
| **Wikibase / Wikidata** | MediaWiki + RDF index | external-API + **SPARQL** | **opaque Q/P id + stmt GUID** | **typed entity-statement graph** | page revisions (JSON) | last-writer + **rank** | **SPARQL (+SERVICE)** | **lossy (not MD)** | none |
| **Anytype** | **CRDT (any-sync)** | **replica / P2P node** | object id (store) | **typed object graph (ontology)** | CRDT log | **native-CRDT** | graph | lossy | **E2EE (whole)** |
| **AFFiNE** | **CRDT (Yjs)** | replica / self-host | block id (store) | blocks; **one-data-many-views** | CRDT log | **native-CRDT** | DB filters | lossy | optional |
| **AppFlowy** | **CRDT (Yrs)** | replica / self-host | block id (store) | **Notion-style DB + views** | CRDT log | **native-CRDT** | DB query | lossy | self-host |
| — *Federated Wiki (mostly a federation model, §2.5)* | per-page JSON | **REST/file-store hybrid** | story-item `id` | typed story items | **append-only journal** | **fork + journal-replay** | neighborhood search | wiki-ish | none |
| — *Xanadu (ideal)* | permascroll | — | **tumbler (span)** | spans + links | permanent | content-merge | — | — | — |
| — *ZigZag (ideal)* | cells/dims | — | cell id | **N dimensions** | — | — | dimension walk | — | — |

Reading top to bottom is roughly shard-wiki's difficulty gradient, now with both ends
extended: the **flat-file floor (Oddmuse/UseModWiki)** anchors the bottom — minimal, partial
history, the field's common ancestor; **git/forge wikis, ikiwiki, Obsidian, Logseq,
TiddlyWiki** are friction-free file-store cases (forge wikis make *git the store itself*);
**TWiki/Foswiki/Trilium/Wiki.js** add translation, DAG/computed metadata, or a git mirror;
**MojoMojo** needs direct-DB reads; **XWiki/Roam/Notion/Quip** add DB/SaaS structure and
store/API addressing; **Wikibase** is the **typed-knowledge-graph far-end** (SPARQL,
statement-level provenance); the **CRDT cohort** adds native merge + (Anytype) P2P/E2EE.
Xanadu/ZigZag mark the ideals; Federated Wiki marks the federation-model ideal (§2.5).

---

## 2. The capability spectra (the contract's real shape) — fourteen

Each capability is **not boolean** — it is a position on a spectrum anchored at each end by
a real system. The contract models *positions*; federation ops degrade by position.

1. **Addressing granularity** — `none → whole-page(path) → page-level store id(Joplin :/id,
   Trilium noteId) → in-file span(Obsidian ^id) → in-file block(Logseq id::, the sweet spot:
   block-level AND git-diffable) → store-minted span(Roam/Notion/CRDT UUID) → statement GUID
   (Wikibase) → portable tumbler(Xanadu ideal)`. Story-item `id` (Federated Wiki) is a
   mid-tier within-page handle. (UC-51, UC-44/45, UC-73.)
2. **Content identity** — `none → path/title → opaque stable id, labels-as-annotation
   (Wikibase Q/P) → fingerprint(hash) → span-set/equivalence(Xanadu)`. Wikibase is the
   cleanest real instance of **stable, language-neutral identity**. (UC-46, UC-27, UC-73.)
3. **Identity vs placement** — `path = identity(most) → identity separated from placement
   (Trilium note/branch; a page in many locations = a DAG) → provenance-edge links across
   sites (Federated Wiki fork-DAG; forge wiki = path, identity layered above)`. The clean
   model for a page under multiple paths/shards. (UC-66, UC-22, UC-71.)
4. **Structure** — `flat Markdown(Oddmuse) → in-file frontmatter/key::(Obsidian/Logseq) →
   in-file %META%(TWiki) → tiddler fields(TiddlyWiki) → relational rows(MojoMojo) → typed
   objects(XWiki) → DB schema+relations+rollups(Notion/AppFlowy) → prose+inline-embedded
   objects(Quip) → typed object graph/ontology(Anytype) → computed inherited+templated
   (Trilium) → typed entity-statement knowledge graph(Wikibase)`. In-text federates;
   DB-locked needs sidecar+fidelity; **graph/computed** needs effective-vs-own +
   render-without-flatten. (UC-34, UC-39, UC-58, UC-67, UC-73, UC-80.)
5. **History** — `none → partial/truncated flat-file(Oddmuse keep/) → internal-only/
   not-portable(Notion/Joplin/Trilium) → DB version rows(MojoMojo) → CRDT update log
   (Anytype/AFFiNE/AppFlowy) → append-only semantic journal(Federated Wiki) → open file
   format(TWiki RCS) → git-native(Git/forge/ikiwiki/Obsidian/Logseq/Wiki.js mirror)`.
   Internal/CRDT/DB-rows ⇒ *supplement*; open-file/journal ⇒ *import*; git ⇒ *adopt*.
   **Completeness is metadata** (Oddmuse history is partial — never imply complete). (UC-36,
   UC-41, UC-71, UC-81, UC-82.)
6. **Merge model** — `none → last-writer → git/text 3-way merge → conflict-notes/keep-both
   (Joplin) → fork + manual journal-replay(Federated Wiki) → coexist-with-rank(Wikibase:
   contradictory values kept, curated) → native-CRDT conflict-free(Anytype/AFFiNE/AppFlowy)`.
   Four+ distinct models — never impose git/text merge on a CRDT or a journal shard; speak
   the shard's model or stay projection/overlay. (UC-64, UC-71, UC-75.)
7. **Native query** — `none → text search → filter expressions(TiddlyWiki) → build-your-own
   derived index(Logseq DataScript over files; shard-wiki can do likewise) → datalog/graph
   (Roam/Anytype) → DB query(Notion/AppFlowy/XWiki) → SPARQL/RDF + federated SERVICE
   (Wikibase, the far-end + query-time cross-shard join)`. Delegate where present; **build an
   index over the projection** where not. (UC-52, UC-63, UC-05, UC-54, UC-74.)
8. **Translation to Markdown** — `native → lossless round-trip(Foswiki TML↔HTML) → lossy-
   with-fidelity-report(HTML/CKEditor Trilium; Notion blocks; Quip HTML+embedded objects;
   CRDT/object models) → not-Markdown-at-all(Wikibase statements → lossy render or keep
   graph)`. Lossless ⇒ writable; lossy ⇒ read/projection floor + visible fidelity loss;
   not-MD ⇒ structured payload + optional rendered view. (UC-42, UC-59, UC-03, UC-73, UC-80.)
9. **Attachment mode** — a **per-binding, capability-gated** choice; a backend may offer
   several. The full taxonomy:
   - **file-store** — *native on-disk store* (Obsidian/Logseq/TWiki), *git IS the store*
     (forge `.wiki.git`, ikiwiki source), *single-file container* (TiddlyWiki HTML),
     *flat-file floor* (Oddmuse), **or** *interchange/sync mirror* (Joplin; Wiki.js git
     mirror) (UC-40, UC-53, UC-60, UC-62, UC-76, UC-78, UC-79, UC-82, UC-68)
   - **in-engine host** — adapter inside the app via its API (Roam/Obsidian/Logseq/Trilium
     scripting, XWiki components) (UC-38, UC-50)
   - **local-REST** — localhost API, app-running (Joplin Data API; Trilium ETAPI) (UC-38)
   - **external-API** — remote API from outside, with a **payload-format facet**:
     *block-JSON* (Notion, UC-57), *GraphQL* (Wiki.js, UC-69), *HTML* (Quip, UC-80),
     *forge wiki REST* (GitLab/Gitea, UC-77), *MediaWiki/SPARQL* (Wikibase, UC-73/74)
   - **direct-DB-read** — read the engine's relational store (MojoMojo) when no file/API
     exists; schema = a versioned coupling (UC-81)
   - **CRDT replica** — hold a local CRDT replica (Anytype/AFFiNE/AppFlowy) (UC-64)
   - **P2P / no-central-endpoint** — replica or peer/node, not a URL (Anytype) (UC-65)
   - **REST/file-store hybrid** — page JSON over HTTP+CORS or static files (Federated Wiki)
     (UC-70)
10. **Operational envelope** — `local/unbounded → realtime CRDT/WebSocket → rate-limited+
    eventually-consistent+paginated(Notion ~3 rps, Quip, Wikibase public endpoints)`. Sets
    live vs cache/poll/webhook. (UC-57, UC-31.)
11. **Access grant** — `open(L0; Oddmuse) → token → OAuth scoped+revocable(Notion) →
    enterprise SSO + ACL(Quip/Salesforce, Wiki.js path rules) → P2P key/invite(Anytype) →
    own-site-only writes(Federated Wiki)`. The backend may *enforce* no-silent-mutation.
    (UC-57, UC-06, UC-65, [[shard-wiki-auth-in-core-decision]].)
12. **Content opacity** — `plaintext(files) → proprietary-but-lossy-exportable(Quip HTML;
    Notion) → encrypted-at-rest whole-shard(Joplin/Anytype E2EE) → per-item(Trilium
    protected notes)`. Opaque ⇒ backup/structure-shell; never present ciphertext (or imply
    a lossy export is faithful) as readable. (UC-61, UC-80.)
13. **Write granularity** — `whole-file(TiddlyWiki single-file) → per-page/note(Git/forge/
    Obsidian/Joplin/Trilium/Oddmuse) → story-item/paragraph(Federated Wiki) → section-anchor
    splice(Quip) → per-statement(Wikibase API) → per-block(Roam/Notion/Logseq/CRDT)`. Sets
    overlay/patch/lock/conflict scope; whole-file ⇒ **no per-page atomicity**. (UC-35,
    UC-78.)
14. **Provenance granularity** *(new, 14th)* — `none → per-shard → per-page(most; author/
    time) → per-commit(git) → per-edit(journal entry, Federated Wiki) → per-statement/value
    (Wikibase references + rank)`. How finely the union can attribute and source content;
    Wikibase pushes provenance below the page (sourced, contradictory values coexist with a
    curation signal). The page model + journal should *allow* sub-page provenance even if MVP
    records per page. (UC-24, UC-71, UC-75.)

*(Content types — Markdown-only → typed records → inline-embedded objects (Quip
spreadsheets) → non-Markdown assets (Excalidraw/Canvas/whiteboards) → typed-graph statements
(Wikibase) — remains a cross-cutting page-model demand, tracked under structure + T12 rather
than as a standalone capability. UC-55.)*

Design consequence: **T11's capability vocabulary = these fourteen spectra**, not a flat
`read/write/diff/...` list. The flat verbs remain the *operations*; the spectra are the
*profile* saying how well each verb is supported and how it degrades. The **floor**
(Oddmuse/UseModWiki) and **far-ends** (Wikibase graph/query/provenance; CRDT merge; Notion
hosted) bound every spectrum with a real system.

---

## 2.5. The federation-model taxonomy (the coordination-layer axis) — new in v3

The fourteen spectra above describe a *single shard's* capabilities. The WP-0003 batch
revealed a second, orthogonal axis the v2 synthesis under-modelled: **federation itself is
plural.** "Attach many shards and present a union" can be realized by several distinct
coordination models, each a real system, each with different reconciliation semantics. This
axis lives at shard-wiki's **coordination layer** (`SHARD-WP-0002` T1–T6), not in a single
adapter.

| Federation model | Exemplar | Mechanism | Reconciliation | Discovery |
|------------------|----------|-----------|----------------|-----------|
| **Fork + journal** | Federated Wiki | copy page to own site; append-only semantic **journal** records `fork`-with-source | **manual**: compare journals, fork the version you prefer; **chorus**, no canonical | link + fork (**neighborhood**) / curated **roster** |
| **VCS replication + ping** | ikiwiki | git clone/pull/push between instances; **XML-RPC pinger** notifies peers to pull/rebuild | **git merge** across clones | configured peers + pings |
| **Query-time graph join** | Wikibase | **SPARQL `SERVICE`** runs a sub-query on another endpoint and joins | none (read-time join; rank curates conflicts) | endpoint URLs |
| **Feed aggregation** | ikiwiki `aggregate`, RSS/Atom | pull remote feeds in as pages | one-way inbound projection | feed URLs |
| **Activity streams** | ActivityPub (federation research) | actor/inbox/outbox Create/Update | per-actor; eventual | actor handles |
| **Engine-maintained mirror** | Wiki.js git mirror | DB-canonical engine syncs to a git mirror | engine owns DB↔git sync (don't double-sync) | the mirror repo |

Two cross-cutting lessons:

- **git-IS-store vs engine-mirror resolves the write-race.** A **forge wiki** (`.wiki.git`)
  and **ikiwiki source** make *git the canonical store*, so **write-by-commit is safe** — no
  engine to race. Wiki.js (engine-mirror, DB canonical) is the opposite and needs care. The
  contract must record *which side is source of truth* per binding. (Resolves UC-68's open
  race for the git-canonical case; UC-76.)
- **shard-wiki's own coordination journal should be journal-shaped.** Federated Wiki proves
  the **append-only semantic-op log with provenance entries, page-state-as-derived-replay**
  pattern in production — the concrete shape for INTENT's coordination journal (UC-71), and a
  superset that can *ingest* git history, CRDT logs, DB version rows, and partial flat-file
  histories as differently-grained inputs.

Design consequence: **T1–T6 should model federation as a selectable model (or composition of
models), not a single hard-coded flow** — mechanism over policy at the coordination layer,
mirroring how T11 models per-shard capability as spectra. A given information space may use
fork+journal for human-curated shards, VCS-replication for git shards, query-join for graph
shards, and feed-aggregation for read-only sources — concurrently.

---

## 3. Cross-cutting findings (the through-lines)

- **Files-canonical, index-derived is the winning architecture.** Obsidian's MetadataCache,
  **Logseq's DataScript-over-files**, Git's working tree, **Wikibase's WDQS (SPARQL index
  rebuilt from canonical JSON entities)**, and shard-wiki's projection model agree: the
  graph/backlinks/query index is **derived and rebuildable**, never a second source of truth.
  Roam/Notion/CRDT invert this (store canonical) and pay in portability. shard-wiki keeps
  files + journal canonical.
- **Git is both the home store and the home journal.** *(sharpened in v3)* Forge wikis make
  git *the* store; ikiwiki and Wiki.js make git the source or mirror; for all of them the
  **git log is the coordination journal with zero synthesis**. The git-canonical cases are
  the friction-free core; everything else is measured as deviation.
- **The flat-file floor is the field's common root.** *(new)* Oddmuse and UseModWiki
  (Wikipedia's MediaWiki Phase I) show the minimal plain-text page+history wiki is the
  ancestor every richer engine elaborates — so the **minimal/floor capability profile** is
  the right baseline, and shard-wiki's page model must stay attach-compatible with it
  (flat files, CamelCase identities, **partial** history). (UC-82.)
- **Federation is plural** *(new — §2.5).* Fork+journal, VCS-replication+ping, query-time
  graph join, feed aggregation, activity streams, engine-mirror — distinct coordination
  models, selectable and composable, not one flow.
- **Provenance has a granularity spectrum** *(new — spectrum 14).* From per-shard down to
  **per-statement/value** (Wikibase references + rank). Union-without-erasure includes
  *attribution at the right grain* and letting sourced contradictions coexist with curation.
- **Identity ≠ placement.** Trilium's **note vs branch** (a note cloned into many locations =
  a DAG) and Wikibase's **opaque stable IDs (labels-as-annotation)** are the clean models:
  separate *what a page is* from *where it sits* and from *what it's called*. Federated
  Wiki's fork entries are **provenance edges** between same-named pages across sites.
- **Transclusion ⇄ clone ⇄ embed ⇄ cloned-note ⇄ reference is one primitive** over an
  addressable union (Xanadu, ZigZag, Roam/Logseq, Obsidian `![[ ]]`, Notion synced block,
  Trilium cloning, TiddlyWiki `{{ }}`). (UC-32/44/45/51/66.)
- **CRDT changes the merge math; journals and rank add more models.** *(extended)* The merge
  spectrum now spans last-writer → git 3-way → conflict-notes → **fork+journal-replay** →
  **coexist-with-rank** → native-CRDT. Never impose git/text merge across that range.
- **Structure & history federate iff in text; metadata can be computed; the far-end is a
  graph.** `%META%`/frontmatter/`key::`/tiddler-fields diff and travel; XObjects/Notion-DB/
  CRDT/Quip-objects lock in; Trilium computes metadata (inherited+templated); **Wikibase is
  a full typed knowledge graph** — render to Markdown is lossy, so keep the graph and offer a
  view, never silent-flatten.
- **The attach surface is rarely "just files," and source-of-truth varies.** *(extended)*
  Joplin's best surface is its sync mirror; Logseq offers file-graph or DB-graph and is
  migrating substrate; **forge wikis = git-canonical (write freely)** vs **Wiki.js =
  DB-canonical mirror (write carefully)** vs **MojoMojo = DB-only (direct read)**. Bind to
  capabilities *and* record the source of truth.
- **The page model must stretch many ways at once:** prose Markdown, typed/computed records
  (N-per-page, relations, inheritance), **inline-embedded objects** (Quip), **typed-graph
  statements** (Wikibase), non-Markdown assets, reference/query-defined pages, and
  **multi-placement (DAG) identity**. The heaviest demand on T12.

---

## 4. How the use cases fold into the workplan

The 260614 + WP-0003 use cases (UC-44–UC-82) map onto the adapter-contract and federation
tasks:

| UCs | Theme | Lands in |
|-----|-------|----------|
| UC-35, UC-50, UC-53, UC-57, UC-60, UC-62, UC-64, UC-65, **UC-68, UC-70, UC-76, UC-77, UC-78, UC-79, UC-80, UC-81, UC-82** | attachment modes (file-store native/git-IS-store/container/mirror, in-engine, local-REST, external-API w/ payload-format, direct-DB, CRDT-replica, P2P, REST/file-store-hybrid) + operational envelope | **T11** + **T14** |
| UC-34, UC-39, UC-55, UC-58, UC-67, **UC-73, UC-80** | structured/typed/computed/**graph** payload, **inline-embedded objects**, non-MD assets | **T12** |
| UC-36, UC-41, **UC-81, UC-82** | history: internal/CRDT-log/**DB-rows**/**partial-flat-file** = supplement; **completeness metadata** | **T13** |
| UC-42, UC-59, **UC-73, UC-80** | translation: lossless vs lossy-with-fidelity vs **not-Markdown** (graph/HTML/objects) | **T15** |
| UC-31, **UC-79** | webhooks / realtime / push-vs-poll / **VCS ping** | **T6** / **T11** envelope |
| UC-57 §6, UC-61, UC-65, **UC-06, UC-80** | scoped grant; **enterprise ACL/SSO**; content opacity (whole/per-item/**lossy-exportable**); P2P key | **T11** (access-grant + opacity) |
| UC-44, UC-45, UC-46, UC-51, UC-63, UC-66, **UC-73, UC-74** | span/statement addressing, **opaque stable identity**, identity≠placement, transclusion-as-reference, derived index, **graph query** | **T16** (+ T12) |
| UC-47, UC-48, UC-52, UC-54, **UC-74** | dimensional navigation, query delegation/build, query-defined pages, **SPARQL/federated SERVICE** | **T16** (+ T5/T10) |
| UC-24, **UC-71, UC-75** | **provenance granularity** (per-edit / per-statement); coordination journal shape | **T13/T16** + journal |
| UC-26, UC-27, UC-28, UC-30, UC-05, **UC-71, UC-72, UC-79** | **federation-model taxonomy** (fork+journal, VCS-replication+ping, query-join, chorus/neighborhood/roster) | **T1–T6** |

The one **structural** v3 change: the **federation-model taxonomy (§2.5)** is a new design
surface for **T1–T6** — federation becomes a *selectable, composable model* rather than a
single flow. Per-shard, **T11** grows to **fourteen spectra** (adds provenance granularity)
and **T14** absorbs the expanded attachment-mode taxonomy (git-IS-store, container,
direct-DB, REST/file-store-hybrid, external-API payload-format facet).

---

## 5. Recommendations (decisions to record under SHARD-WP-0002)

1. **Model per-shard capabilities as the fourteen spectra (§2)**, not flat verbs. (T11.)
2. **Model federation as a selectable/composable taxonomy of models (§2.5)** — fork+journal,
   VCS-replication+ping, query-time graph join, feed aggregation, activity streams,
   engine-mirror — at the coordination layer. (T1–T6.)
3. **Make the coordination journal journal-shaped** (Federated Wiki): append-only semantic
   ops + provenance entries, page state = derived replay; able to *ingest* git history, CRDT
   logs, DB version rows, and partial flat-file histories as differently-grained inputs.
   (T13 + journal, UC-71.)
4. **Add provenance granularity as a spectrum** (per-shard → per-page → per-edit →
   per-statement/value); allow sub-page provenance and **coexist-with-rank** for sourced
   contradictions. (T11/T13, UC-24/75.)
5. **Record source-of-truth per binding** and resolve the write-race accordingly:
   git-canonical (forge wiki / ikiwiki) ⇒ write-by-commit; engine-mirror (Wiki.js) ⇒ careful;
   direct-DB (MojoMojo) ⇒ read/projection/overlay default. (T14, UC-68/76/79/81.)
6. **Expand attachment mode (§2 #9 / T14):** file-store (native / **git-IS-store** /
   **container** / mirror / **flat-file floor**), in-engine, local-REST, **external-API with
   a payload-format facet** (block-JSON/GraphQL/HTML/forge-REST/SPARQL), **direct-DB-read**,
   CRDT-replica, P2P, **REST/file-store-hybrid**. Bind to capabilities; substrate can
   migrate. (T14, UC-40/68/70/76/77/78/79/80/81/82 + UC-43.)
7. **Page model: support a typed-graph payload and inline-embedded objects, not only
   typed records** — render to Markdown lossily, keep the graph/objects canonical; preserve
   computed (inherited/templated) metadata as effective-vs-own. (T12/T15, UC-73/80/67.)
8. **Capability profile must express absence and partiality cleanly** (Oddmuse floor):
   sparse profiles, **partial/truncated history reported honestly**, graceful degradation to
   read/projection/overlay/backup. (T11/T13, UC-82.)
9. **Query: SPARQL/RDF + federated `SERVICE` is the graph far-end** — delegate to native
   engines (filters/datalog/DB-query/SPARQL) where present; build a derived index over the
   projection where not. (T16/T5, UC-52/63/74.)
10. **Adopt opaque stable identity with labels-as-annotation** (Wikibase) and **separate
    identity from placement** (Trilium note/branch); fork entries are provenance edges.
    (T16, UC-73/66/71.)
11. **Keep files + coordination journal canonical; all indexes/projections derived and
    rebuildable.** (Architecture invariant, INTENT.)

These honor INTENT: mechanism over policy (capability *and now federation* modelled as
spectra/taxonomy, not hard-coded behaviors), union without erasure (fidelity +
effective-vs-own + identity/placement + **provenance granularity** all preserve
information), graceful degradation (every spectrum has a read/projection floor; the
Oddmuse floor is explicit; opaque/CRDT/graph shards degrade to backup/projection/lossy-view),
no silent mutation (access-grant + opacity + overlay + respect native merge + **source-of-
truth per binding**), shard sovereignty (no backend forced to change substrate),
Markdown-first/backend-neutral (in-text preferred; DB/CRDT/HTML/**graph** tolerated with a
view).

---

## 6. Open questions escalated by the synthesis

1. **Federation composition** — can one information space run several federation models
   (§2.5) concurrently over different shards, and how does the union reconcile a chorus
   (fork+journal) with a canonical-asserting shard (Notion / upstream main)? (T1–T6,
   UC-72.)
2. **Coordination-journal op vocabulary** — adopt Federated Wiki's exact ops
   (create/add/edit/move/remove/fork) at item grain, or an abstract op set other shards can
   emit, with git/CRDT/DB-row/flat-file histories ingested as inputs? (T13, UC-71.)
3. **Provenance granularity in the model** — does the journal/page model carry per-statement
   provenance + rank (Wikibase), per-edit (journal), or per-page (MVP), configurable? (T13,
   UC-75.)
4. **Typed-graph page** — model a Wikibase entity natively (statements) or always project to
   a lossy Markdown/table view, or both (canonical graph + view)? Is SPARQL a union-level
   capability or pass-through? (T12/T16, UC-73/74.)
5. **Source-of-truth + write-race** — formalize git-canonical vs engine-mirror vs direct-DB
   per binding; sanction direct third-party DB reads (schema drift) and write-by-commit
   timing. (T14, UC-68/76/79/81.)
6. **Portable span address** across heterogeneous backends — wrap native IDs (Roam/Notion/
   CRDT UUID, Logseq `id::`, Trilium noteId, **Wikibase Q/P + stmt GUID**, fedwiki story-item
   id) in a shard-scoped address? (T16.)
7. **CRDT shards** — embed a CRDT client (Yjs/Yrs) for a live replica, or consume snapshots?
   Overlays as CRDT ops or out-of-band patches? (T14, UC-64.)
8. **Page model breadth** — can one model carry prose + typed/computed records +
   inline-embedded objects + typed-graph statements + non-MD assets + query-defined pages +
   multi-placement identity coherently? (T12.)
9. **Whole-file & partial-history shards** — overlays against a whole-file shard
   (TiddlyWiki single-file: buffer+re-serialize vs require `.tid`); representing
   partial/truncated history (Oddmuse) with completeness metadata. (T11/T13, UC-78/82.)
10. **Content opacity & lossy-exportable** — what is visible for an opaque/proprietary shard
    (IDs/structure vs nothing vs lossy HTML); never present a lossy export as faithful; does
    shard-wiki ever hold keys? (T11, UC-61/80.)

---

## 7. Sources

A synthesis; primary sources are the ~23 dives' `findings.md` files plus
`research/260608-{federation-concepts,wikiengines-overview,c2-wiki-origins,yawex-prior-art}`.
No new external research was performed in v3 (it consolidates the WP-0003 batch dives
260614-{federated-wiki,wikibase,forge-wikis,tiddlywiki,ikiwiki,quip,mojomojo,oddmuse,
usemodwiki}).

Cross-references: `spec/UseCaseCatalog.md` (UC-26–UC-82),
`workplans/SHARD-WP-0002-federation-architecture.md` (T1–T16),
`workplans/SHARD-WP-0003-engine-dives-batch.md` (the engine batch, done),
`INTENT.md` (constraints), [[shard-wiki-auth-in-core-decision]].

---

## 8. Traceability

- Consolidates: all ~23 deep dives + federation/origin research into one capability model
  (v3 adds the WP-0003 batch).
- Feeds: `SHARD-WP-0002` **T1–T6** (federation-model taxonomy §2.5 — selectable/composable
  federation), **T11** (**fourteen-spectra** vocabulary, incl. provenance granularity +
  expanded attachment modes + payload-format facet), T12 (page-model breadth: typed-graph,
  inline-embedded objects, computed metadata, identity≠placement, non-MD), T13 (history incl.
  DB-rows + partial-flat-file = supplement, completeness metadata, journal-shaped
  coordination journal), T14 (full attachment taxonomy incl. git-IS-store / container /
  direct-DB / REST-file-hybrid + source-of-truth per binding), T15 (lossy + not-Markdown
  graph/HTML), T16 (addressing incl. statement GUID + opaque stable identity, graph query /
  federated SERVICE).
- UC coverage extended in the workplan from UC-34–UC-67 to **UC-34–UC-82**.
- No UCs added (synthesis only); no boundary changes (INTENT Stability Note untouched —
  the federation-model taxonomy is a refinement of *how* the coordination layer works, not a
  redefinition of shard / Git's role / orchestrator-vs-engine).