synthesis: shard spectrum across nine systems; fold into SHARD-WP-0002 (T11 eleven spectra, new T16)

Cross-dive synthesis (research/260614-shard-spectrum-synthesis/) reading
the two Nelson conceptual systems, four engines, and three modern tools
across each other: a shard family matrix and eleven capability spectra
(addressing, content identity, structure, history, native query,
translation, attachment mode, operational envelope, access grant, write
granularity, content types) — positions anchored at both ends by a real
system, federation ops degrading by position. Through-lines:
files-canonical/index-derived wins; fine-grained addressing is adoptable;
transclusion=clone=embed is one primitive; structure/history federate iff
in-text; attach mode is a per-binding choice; Notion proves the platform
can enforce no-silent-mutation.

Folded into SHARD-WP-0002: T11 reframed around the eleven spectra; T12
page model stretched four ways (prose + typed records + non-Markdown
assets + query-defined); T13 adds Notion supplement; T14 rewritten as the
three-mode attachment taxonomy (file-store / in-engine-host /
external-API); T15 adds lossy-with-fidelity-report; new T16 (addressing,
content identity, dimensional/query navigation). UC coverage UC-34-43 ->
UC-34-59. Workplan now 16 tasks. No new UCs (synthesis only).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

SCOPE.md

@@ -22,7 +22,7 @@ Learnings update both SCOPE and INTENT where necessary.
 | Research | yawex prior art; c2 origins; federation concepts; wikiengines overview (`research/260608-*/`); XWiki/TWiki/Foswiki deep dives (`research/260613-*/`); Xanadu + ZigZag + Roam + Obsidian + Notion deep dives (`research/260614-*/`) |
 | Demand | NetKingdom integration asks captured, not yet negotiated |
 | Spec | Architecture blueprint drafted; UseCaseCatalog 59 UCs from research; PRD/TSD scaffolds |
-| Work | `SHARD-WP-0001` active (6 tasks); `SHARD-WP-0002` active (10 tasks) |
+| Work | `SHARD-WP-0001` active (6 tasks); `SHARD-WP-0002` active (16 tasks: T1–T10 federation + T11–T16 adapter contract) |
 
 ## In Scope (today)
 

research/260614-shard-spectrum-synthesis/README.md

@@ -0,0 +1,47 @@
+# 260614 — Shard spectrum synthesis (one capability model across nine systems)
+
+Date: 2026-06-14
+
+## What this is
+
+A **synthesis** (no new external research) that reads the nine studied systems *across*
+each other and distills them into a single comparative model feeding the **shard adapter
+contract** (`SHARD-WP-0002`).
+
+The nine: two conceptual ancestors (**Xanadu**, **ZigZag**), four engines (**XWiki,
+TWiki, Foswiki** + the wiki-engines landscape), and three modern tools (**Roam,
+Obsidian, Notion**), against the federation/origin research.
+
+Centerpieces:
+- **The shard family matrix** — every candidate backend × {substrate, attach mode,
+  addressing, structure, history, query, transclusion, →Markdown, write granularity},
+  with Xanadu/ZigZag as the ideal anchors.
+- **The eleven capability spectra** — the claim that the adapter contract should model
+  *positions on spectra* (addressing, content identity, structure, history, query,
+  translation, attachment mode, operational envelope, access grant, write granularity,
+  content types), each anchored at both ends by a real system, with federation ops
+  degrading by position.
+- **UC-44–UC-59 → workplan task mapping**, including one genuinely new thread (T16:
+  addressing, content identity, dimensional/query navigation).
+
+## Contents
+
+| Path | Role |
+|------|------|
+| `findings.md` | Family matrix, the eleven spectra, cross-cutting through-lines, UC→task fold-in, recommendations/decisions, escalated open questions |
+
+## Status
+
+Synthesis complete. No new use cases (consolidation only). Feeds `SHARD-WP-0002`: T11
+reframed around the eleven spectra; T12 page-model breadth (prose + typed records +
+non-Markdown assets + query-defined); T13 history confirmed; T14 three-mode attachment
+taxonomy; T15 lossy-with-fidelity-report; **new T16** (addressing, content identity,
+dimensional/query navigation). UC coverage in the workplan extended UC-34–UC-43 →
+UC-34–UC-59.
+
+**Through-lines recorded:** files-canonical/index-derived is the winning architecture;
+fine-grained addressing is real and adoptable (adopt native, fingerprint otherwise);
+transclusion ⇄ clone ⇄ embed is one primitive; structure/history federate iff in text;
+attach mode is a per-binding capability-gated choice; Notion proves the platform can
+*enforce* no-silent-mutation via scoped grants.
+</content>

research/260614-shard-spectrum-synthesis/findings.md

@@ -0,0 +1,220 @@
+# Synthesis — the shard spectrum: one capability model across nine systems
+
+Date: 2026-06-14
+Source kind: **synthesis** — consolidates the engine and tool deep dives plus the two
+Nelson conceptual systems into a single comparative model that feeds the **shard adapter
+contract** (`SHARD-WP-0002` T11–T16)
+Lens: shard-wiki — what a backend must expose to participate, expressed as *spectra* of
+capability rather than a yes/no checklist
+
+> Purpose. Nine systems have been studied: two conceptual ancestors (**Xanadu**,
+> **ZigZag**), four engines (**XWiki, TWiki, Foswiki**, + the wiki-engines landscape),
+> and three modern tools (**Roam, Obsidian, Notion**), against the federation and
+> origin research (federation-concepts, c2, yawex). They were studied one at a time;
+> this document reads them *across* each other. The payoff is a small set of
+> **capability spectra** — addressing, structure, history, query, translation,
+> attachment mode, operational envelope, access grant — each anchored at both ends by a
+> real system. That spectrum *is* the adapter contract's design surface. It also folds
+> the post-engine use cases (**UC-44–UC-59**) into the existing `SHARD-WP-0002` tasks.
+
+Inputs: `research/260608-federation-concepts`, `research/260608-wikiengines-overview`,
+`research/260613-{xwiki,twiki,foswiki}-deep-dive`,
+`research/260614-{xanadu,zigzag,roam,obsidian,notion}-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; listed
+last as reference anchors.)
+
+| Backend | Substrate | Attach mode | Addressing | Structure | History | Native query | Transclusion | →Markdown | Write granularity |
+|---------|-----------|-------------|-----------|-----------|---------|--------------|-------------|-----------|-------------------|
+| **Git folder / repo** | files | file-store | path (+ commit) | flat MD + frontmatter | **git-native** | no | no | native | per-file |
+| **Obsidian vault** | files | file-store **or** in-app plugin | path + **in-file `^id`** | frontmatter (in-file) | none (Git plugin) | plugin (Dataview) | in-file `![[ ]]` | native (OFM) | per-file |
+| **TWiki** | files + RCS | file-store / API | path | `%META%` in-file | **open file (RCS)** | no | include macro | lossless (TML) | per-topic |
+| **Foswiki** | pluggable store | file-store / API | path | `%META%` in-file, N records | open file / PlainFile | no | include macro | lossless (TML) | per-topic |
+| **XWiki** | DB (Hibernate) | in-engine host / REST | path | **XObjects/XClass** | internal (`xwikircs`) | yes (XWQL) | macro | engine syntax | per-page / per-object |
+| **Roam** | client DataScript | **in-app host only** | **store UUID** | `key::` attrs | internal (txn log) | **yes (Datalog)** | **block embed** | (Roam MD) | **per-block** |
+| **Notion** | hosted Postgres | **external API only** | **store UUID** | **DB schema + relations + rollups** | internal, not portable | **yes (DB query)** | synced block | **lossy** | **per-block** |
+| **TiddlyWiki** | single file | file-store | path | typed tiddlers | none | no | transclusion | varies | **whole-file** |
+| **MediaWiki / Confluence** | DB | API | path | wikitext / macros | internal-only | limited | templates | lossy | per-page |
+| — *Xanadu (ideal)* | permascroll | — | **tumbler (span)** | spans + links | permanent | — | **content-identity** | — | span |
+| — *ZigZag (ideal)* | cells/dims | — | cell id | **N dimensions** | — | dimension walk | clone | — | cell |
+
+Reading the matrix top to bottom is reading shard-wiki's difficulty gradient: **Git
+folder → Obsidian** are the friction-free, INTENT-native cases; **TWiki/Foswiki** add
+syntax translation but stay file/diffable; **XWiki/Roam/Notion** add DB structure, store
+addressing, and (for Roam/Notion) non-file substrates; **Notion** is the hardest
+(closed, hosted, lossy, rate-limited). Xanadu/ZigZag mark where the *ideals* live.
+
+---
+
+## 2. The capability spectra (the contract's real shape)
+
+Each capability is **not boolean** — it is a position on a spectrum with a real anchor at
+each end. This is the core synthesis claim: the adapter contract should model *positions*,
+and federation operations should degrade by position.
+
+1. **Addressing granularity** — `none → whole-page(path) → in-file span(Obsidian ^id) →
+   store-minted span(Roam/Notion UUID) → portable tumbler(Xanadu ideal)`. (UC-51, UC-44/45.)
+2. **Content identity** — `none → path/title match → content fingerprint(hash) →
+   span-set/equivalence(Xanadu)`. Drives equivalence + reverse-transclusion. (UC-46, UC-27.)
+3. **Structure** — `flat Markdown → in-file frontmatter → in-file %META% → DB
+   objects(XWiki) → DB schema+relations+rollups(Notion)`. The git-diffable forms federate
+   easily; DB-locked forms need sidecar + fidelity reporting. (UC-34, UC-39, UC-58.)
+4. **History** — `none → internal-only/not-portable(Notion/Confluence) → open file
+   format(TWiki RCS) → git-native(Git/Obsidian-with-Git)`. Internal ⇒ *supplement*;
+   open-file ⇒ *import*; git-native ⇒ *adopt*. (UC-36, UC-41.)
+5. **Native query** — `none → text search → datalog(Roam) → DB query(Notion/XWiki)`.
+   Where present, **delegate** derived-view computation; else compute over the projection.
+   (UC-52, UC-05, UC-54.)
+6. **Translation to Markdown** — `native → lossless round-trip(Foswiki TML↔HTML) →
+   lossy-with-fidelity-report(Notion)`. Lossless ⇒ writable; lossy ⇒ read/projection floor
+   + visible fidelity loss. (UC-42, UC-59, UC-03.)
+7. **Attachment mode** — `file-store direct(Obsidian/TWiki) → in-engine hosted
+   adapter(Roam/XWiki) → external-API only(Notion)`. A backend may offer **more than one**
+   (Obsidian offers both; TWiki file-or-API). (UC-40, UC-38, UC-50, UC-57.)
+8. **Operational envelope** — `local/unbounded → rate-limited+eventually-consistent+
+   paginated(Notion ~3 rps)`. Determines whether projection can be live or must be
+   cache/poll/webhook. (UC-57, UC-31.)
+9. **Access grant** — `open(L0) → token → OAuth scoped + revocable(Notion)`. The backend
+   may *enforce* no-silent-mutation (Notion scoped grants). Ties the authz-in-core ladder.
+   (UC-57, [[shard-wiki-auth-in-core-decision]].)
+10. **Write granularity** — `whole-file(TiddlyWiki) → per-page(Git/Obsidian/TWiki) →
+    per-block(Roam/Notion)`. Sets overlay/patch/lock/conflict scope. (UC-35.)
+11. **Content types** — `Markdown-only → typed records(XWiki/Notion DB) → non-Markdown
+    assets(Excalidraw/Canvas/attachments)`. The page model must stretch to all three.
+    (UC-55, UC-58.)
+
+Design consequence: **T11's capability vocabulary should be these eleven spectra**, not
+the original flat `read/write/diff/...` list. The flat verbs remain as the *operations*;
+the spectra are the *profile* that says how well each verb is supported and how it
+degrades.
+
+---
+
+## 3. Cross-cutting findings (the through-lines)
+
+- **Files-canonical, index-derived is the winning architecture.** Obsidian's
+  MetadataCache, Git's working tree, and shard-wiki's own projection model all agree:
+  the link graph / backlinks / structured index are **derived and rebuildable**, never a
+  second source of truth. Roam/Notion invert this (DB canonical) and pay for it in
+  portability. shard-wiki keeps files+journal canonical; everything else is projection.
+  (Reinforces UC-05, UC-17–20; INTENT.)
+- **Fine-grained addressing is real and adoptable** — Roam (`:block/uid`) and Notion
+  (UUID) ship it store-minted; Obsidian ships it in-file (`^id`). The Xanadu tumbler is
+  the unreached ideal (portable, transfinite). shard-wiki should **adopt native span IDs
+  where present, fingerprint where not** (UC-51 + UC-46), and treat a portable span
+  address as the open hard problem (Xanadu §11 Q1).
+- **Transclusion ⇄ clone ⇄ embed is one primitive.** Xanadu transclusion, ZigZag clones,
+  Roam block embeds, Obsidian `![[ ]]`, Notion synced blocks are the same idea at
+  different fidelities. A single internal "reference-not-copy" primitive over an
+  addressable union serves UC-32/44/45/51. (Convergence first noted in the ZigZag dive.)
+- **Structure and history federate iff they live in text.** The sharpest recurring
+  engine insight: `%META%`-in-file (TWiki/Foswiki) and frontmatter (Obsidian) diff and
+  travel; XObjects and Notion DBs lock in. The contract should *prefer* in-text
+  structure and *tolerate* DB structure via sidecar + fidelity report.
+- **Three attachment modes, and a backend may span them.** The clean taxonomy
+  (file-store / in-engine-host / external-API) plus the observation that one backend can
+  offer several (Obsidian: file *or* plugin; TWiki: file *or* API) means **attach mode is
+  a per-binding choice, capability-gated**, not a fixed property of the backend.
+- **Notion proves the platform can enforce INTENT.** Scoped, revocable grants are
+  no-silent-mutation made mechanical — evidence the principle is implementable, and a
+  model for how shard-wiki represents partial/consented visibility.
+- **The page model must stretch four ways at once:** prose Markdown, typed records
+  (with N-per-page and inter-record relations), non-Markdown assets, and
+  reference/query-defined pages. This is the heaviest single demand on T12.
+
+---
+
+## 4. How the post-engine use cases fold into the workplan
+
+UC-44–UC-59 (from the five 260614 dives) map onto the existing adapter-contract tasks,
+with one genuinely new thread needing a home (T16):
+
+| UCs | Theme | Lands in |
+|-----|-------|----------|
+| UC-35, UC-50, UC-53, UC-57 | attachment mode + operational envelope + write granularity | **T11** (capabilities) + **T14** (binding) |
+| UC-34, UC-39, UC-55, UC-58 | structured/typed payload, non-Markdown assets, DB schema+relations | **T12** (page model) |
+| UC-36 | internal-only history (Notion) = supplement | **T13** (history) |
+| UC-42, UC-59 | translation: lossless vs lossy-with-fidelity-report | **T15** (translation) |
+| UC-31 | webhooks / push-vs-poll under eventual consistency | **T6** / **T11** envelope |
+| UC-57 §6 | scoped, revocable grant; no silent mutation | **T11** access-grant + authz decision |
+| **UC-44, UC-45, UC-46, UC-51** | span addressing, content identity, transclusion-as-reference | **T8** + **new T16** |
+| **UC-47, UC-48, UC-52, UC-54** | dimensional navigation, query delegation, query-defined pages | **T5/T10** + **new T16** |
+
+**New thread (T16): Addressing, content identity, and dimensional/query navigation.** No
+existing task owns (a) the portable span-address scheme + content-identity model that
+transclusion/overlay/reverse-lookup need, nor (b) the dimensional/query view model
+(ZigZag dimensions, Roam/Notion query, Dataview query-defined pages). These are the
+Nelson-ideals-meet-modern-tools thread and warrant their own design task.
+
+---
+
+## 5. Recommendations (decisions to record under SHARD-WP-0002)
+
+1. **Model capabilities as the eleven spectra (§2), not flat verbs.** Keep verbs as
+   operations; add the spectra as the profile. (T11.)
+2. **Adopt native span IDs; fingerprint otherwise; keep portable-span-address open.**
+   (T16, UC-51/46.)
+3. **One reference-not-copy primitive** for transclusion/clone/embed over the addressable
+   union. (T16/T8, UC-32/44/45.)
+4. **Prefer in-text structure; tolerate DB structure via sidecar + fidelity report.**
+   (T12/T15, UC-34/58/59.)
+5. **Attach mode is a per-binding, capability-gated choice** across the three modes; a
+   backend may offer several. (T14, UC-40/38/50/57.)
+6. **Add operational-envelope and access-grant to the profile** as first-class fields.
+   (T11, UC-57.)
+7. **Delegate derived views to native query engines where present; else compute over the
+   projection.** (T16/T5, UC-52/54.)
+8. **Keep files + coordination journal canonical; all indexes/projections derived and
+   rebuildable.** (Architecture invariant, INTENT.)
+
+These honor INTENT: mechanism over policy (spectra not hard-coded behaviors), union
+without erasure (fidelity reporting makes loss visible), graceful degradation (every
+capability has a read/projection floor), no silent mutation (access-grant + overlay),
+shard sovereignty (no backend forced to change substrate), Markdown-first/backend-neutral
+(in-text preferred, DB tolerated).
+
+---
+
+## 6. Open questions escalated by the synthesis
+
+1. **Portable span address** — still unsolved across heterogeneous backends (Xanadu's
+   unbuilt part). Wrap native IDs in a shard-scoped address? (T16.)
+2. **External-API write-through at scale** — is Notion-class write viable under ~3 rps,
+   or read/projection/overlay/backup by default? (T14, UC-57.)
+3. **Inter-record relations in the union** (UC-58) — typed links in the link graph, a
+   separate relation index (ZigZag many-to-many), or both? (T16/T5.)
+4. **Page model breadth** — can one model carry prose + typed records + non-Markdown
+   assets + query-defined pages without becoming incoherent? (T12.)
+5. **Dimensional navigation surface** — public API/UI paradigm or internal organizing
+   concept? (T16, UC-47/48.)
+
+---
+
+## 7. Sources
+
+This is a synthesis; primary sources are the nine dives' `findings.md` files plus
+`research/260608-federation-concepts`, `research/260608-wikiengines-overview`,
+`research/260608-c2-wiki-origins`, `research/260608-yawex-prior-art`. No new external
+research was performed.
+
+Cross-references: `spec/UseCaseCatalog.md` (UC-26–UC-59),
+`workplans/SHARD-WP-0002-federation-architecture.md` (T1–T16),
+`INTENT.md` (constraints), [[shard-wiki-auth-in-core-decision]].
+
+---
+
+## 8. Traceability
+
+- Consolidates: nine deep dives + federation/origin research into one capability model.
+- Feeds: `SHARD-WP-0002` T11 (eleven-spectra vocabulary), T12 (page-model breadth), T13
+  (history confirmed), T14 (three-mode attachment taxonomy), T15 (lossy fidelity report),
+  and a **new T16** (addressing, content identity, dimensional/query navigation).
+- UC coverage extended in the workplan from UC-34–UC-43 to **UC-34–UC-59**.
+- No UCs added (synthesis only); no boundary changes (INTENT Stability Note untouched).
+</content>

research/README.md

@@ -21,4 +21,5 @@ when multiple files or sources are involved. Findings here inform `spec/` and
 | 2026-06-14 | `260614-zigzag-deep-dive/` | ZigZag/zzstructure — information space as orthogonal dimensions; UC-47/48/49 |
 | 2026-06-14 | `260614-roam-deep-dive/` | Roam Research — block-graph DataScript DB, transclusion, datalog, Roam Depot extension API; UC-50/51/52 |
 | 2026-06-14 | `260614-obsidian-deep-dive/` | Obsidian — file-over-app vaults, plugin API, ecosystem-popularity → UC signal; UC-53/54/55/56 |
-| 2026-06-14 | `260614-notion-deep-dive/` | Notion — closed block-DB SaaS, external REST API only, database-as-pages; UC-57/58/59 |
+| 2026-06-14 | `260614-notion-deep-dive/` | Notion — closed block-DB SaaS, external REST API only, database-as-pages; UC-57/58/59 |
+| 2026-06-14 | `260614-shard-spectrum-synthesis/` | Synthesis — shard family matrix + eleven capability spectra across nine systems; feeds SHARD-WP-0002 T11–T16 |

workplans/SHARD-WP-0002-federation-architecture.md

@@ -27,13 +27,21 @@ UC-26–UC-33.
 Primary deliverable: `spec/FederationArchitecture.md` (created and filled by
 this workplan's tasks).
 
-Secondary deliverable (T11–T15, added 2026-06-13): the **shard adapter contract**
+Secondary deliverable (T11–T16): the **shard adapter contract** constraints distilled
-constraints distilled from the engine deep dives, feeding
+from the engine deep dives (T11–T15, added 2026-06-13) and the modern-tool dives +
+cross-dive synthesis (T16 and scope extensions, added 2026-06-14), feeding
 `spec/TechnicalSpecificationDocument.md`. Federation architecture decides *what the
 union does*; the adapter contract decides *what a backend must expose to participate*.
 The two are co-dependent (the capability matrix T10 consumes the contract vocabulary
 T11 defines), so they live in one workplan.
 
+The cross-dive synthesis (`research/260614-shard-spectrum-synthesis/findings.md`)
+reframes the contract around **eleven capability spectra** (addressing, content
+identity, structure, history, native query, translation, attachment mode, operational
+envelope, access grant, write granularity, content types) — positions on a spectrum
+anchored at both ends by a real system, with federation ops degrading by position —
+rather than a flat verb checklist.
+
 ## Context
 
 - Federation research: `research/260608-federation-concepts/findings.md`
@@ -44,8 +52,21 @@ T11 defines), so they live in one workplan.
   - `research/260613-twiki-deep-dive/findings.md` (file+RCS app-platform)
   - `research/260613-foswiki-deep-dive/findings.md` (`Foswiki::Store` versioned
     store interface = adapter-contract prior art)
-- Use cases: `spec/UseCaseCatalog.md` § A (UC-26–UC-43; UC-34–43 are the
+- Conceptual + modern-tool dives (T16 + scope extensions, 2026-06-14):
-  engine-attachment / adapter-contract cases)
+  - `research/260614-xanadu-deep-dive/findings.md` (reference-not-copy, transclusion,
+    tumbler span addressing — ideal)
+  - `research/260614-zigzag-deep-dive/findings.md` (information space as co-equal
+    dimensions; clone = transclusion — ideal)
+  - `research/260614-roam-deep-dive/findings.md` (block-DB, store UUIDs, Datalog,
+    in-app host)
+  - `research/260614-obsidian-deep-dive/findings.md` (file-over-app, in-file `^id`,
+    MetadataCache derived index, dual attach, ecosystem popularity)
+  - `research/260614-notion-deep-dive/findings.md` (closed SaaS, external-API-only,
+    DB schema+relations, operational envelope, scoped grant)
+  - `research/260614-shard-spectrum-synthesis/findings.md` (**synthesis**: the eleven
+    capability spectra, shard family matrix, UC→task fold-in)
+- Use cases: `spec/UseCaseCatalog.md` § A (UC-26–UC-59; UC-34–UC-43 are the
+  engine-attachment cases, UC-44–UC-59 the conceptual + modern-tool cases)
 - Aspiration: `INTENT.md` (orchestrator, not engine; mechanism over policy;
   capability-aware adapters; Markdown-first, backend-neutral)
 - Related workplan: `SHARD-WP-0001` (page resolution, namespaces, overlays,
@@ -74,11 +95,12 @@ decision records only.
 
 | Topic | Key tradeoff | Primary UCs |
 |-------|--------------|-------------|
-| Adapter contract & capabilities | Versioned interface + capability vocabulary; write granularity | UC-02, UC-35, UC-38 |
+| Adapter contract & capabilities | Eleven spectra (not flat verbs); write granularity; operational envelope; access grant | UC-02, UC-35, UC-38, UC-57 |
-| Structured page model | Typed frontmatter vs sidecar vs blob; bodiless / multi-record pages | UC-34, UC-39 |
+| Structured page model | Typed frontmatter vs sidecar vs blob; bodiless / multi-record; DB schema+relations; non-Markdown assets; query-defined pages | UC-34, UC-39, UC-55, UC-58, UC-54 |
-| History portability | Supplement (DB-internal) vs import (open file history) | UC-36, UC-41 |
+| History portability | Supplement (DB-internal, incl. Notion) vs import (open file history) | UC-36, UC-41 |
-| Adapter binding | Runtime API vs on-disk store; engine-hosted vs external; backend-swap | UC-38, UC-40, UC-43 |
+| Adapter binding | Three modes (file-store / in-engine-host / external-API); per-binding choice; backend-swap; scoped grant | UC-38, UC-40, UC-43, UC-50, UC-57 |
-| Syntax translation | Lossless non-Markdown round-trip vs read-only degradation | UC-42, UC-03 |
+| Syntax translation | Lossless round-trip vs **lossy-with-fidelity-report** vs read-only degradation | UC-42, UC-59, UC-03 |
+| Addressing, identity & navigation (T16) | Span addressing; content identity; transclusion-as-reference; dimensional/query views | UC-44, UC-45, UC-46, UC-47, UC-48, UC-51, UC-52, UC-54 |
 
 ---
 
@@ -338,14 +360,27 @@ Define the **capability-aware shard adapter contract** as a *versioned* interfac
 taking `Foswiki::Store` + `Foswiki::Meta` as direct prior art (a real engine that
 already separates store backend from core behind a stable interface).
 
-- Capability vocabulary: `read, write, diff, merge, lock, version, publish, notify,
+- **Operation verbs:** `read, write, diff, merge, lock, version, publish, notify,
   transclude-source, translate-syntax, structured-payload` (reconcile with T10).
-- **Write granularity** as a first-class capability dimension: per-page / per-file /
+- **Capability profile = the eleven spectra** (synthesis §2), each a *position* not a
-  per-space / append-only (TiddlyWiki single-file vs DB whole-space vs TWiki per-topic).
+  boolean, so federation ops degrade by position:
-- Versioning/compatibility rules for the contract itself; capability discovery.
+  1. addressing granularity (none → path → in-file span → store-UUID → portable tumbler)
+  2. content identity (none → path/title → fingerprint → span-set)
+  3. structure (flat MD → frontmatter → %META% → DB objects → DB schema+relations)
+  4. history (none → internal-only → open-file → git-native)
+  5. native query (none → text → datalog → DB query)
+  6. translation (native → lossless → lossy-with-fidelity-report)
+  7. attachment mode (file-store → in-engine-host → external-API)
+  8. operational envelope (local/unbounded → rate-limited/eventually-consistent/paginated)
+  9. access grant (open → token → OAuth scoped+revocable)
+  10. write granularity (whole-file → per-page → per-block)
+  11. content types (Markdown-only → typed records → non-Markdown assets)
+- Versioning/compatibility rules for the contract itself; capability discovery
+  (static profile vs runtime negotiation).
 
-**Inputs:** `260608-wikiengines-overview` §3, §5; `260613-foswiki-deep-dive` §2, §6.
+**Inputs:** `260608-wikiengines-overview` §3, §5; `260613-foswiki-deep-dive` §2, §6;
-**Provides** the vocabulary T10's matrix consumes. **UCs:** UC-02, UC-35, UC-38.
+`260614-shard-spectrum-synthesis` §2, §5. **Provides** the vocabulary T10's matrix
+consumes. **UCs:** UC-02, UC-35, UC-38, UC-57.
 
 **Tradeoffs:** Rich capability set (precise degradation) vs contract complexity;
 static profile vs runtime capability negotiation.
@@ -364,17 +399,32 @@ state_hub_task_id: "7334a4a4-ba75-4fac-a8b4-8350d342b299"
 Decide how the **backend-neutral, Markdown-first page model carries structured data
 without flattening**:
 
+The model must stretch **four ways at once** (synthesis §3): prose Markdown, typed
+records, non-Markdown assets, and reference/query-defined pages.
+
 - Source shapes: XWiki XObjects against an XClass; TWiki/Foswiki DataForms stored as
   `%META:FIELD%` in text; Foswiki MetaDataPlugin **multiple records per topic**;
-  Semantic MediaWiki annotations.
+  Semantic MediaWiki annotations; **Notion databases** (schema + typed properties +
+  inter-record **relations** + rollups/formulas) — the apex of database-as-pages.
 - Representation choice: typed frontmatter vs sidecar file vs opaque provenance blob.
+  Prefer **in-text structure** (frontmatter/`%META%`, git-diffable); tolerate DB
+  structure via sidecar + fidelity report (T15).
 - **Bodiless pages** (UC-39): may a page be purely structured, no Markdown body?
 - **N typed records per page** (not one form) must be representable.
+- **Non-Markdown content types** (UC-55): drawings (Excalidraw), spatial canvases
+  (JSON Canvas), images, attachments — typed asset vs opaque blob vs content-type
+  registry, with provenance, not flattened away.
+- **Inter-record relations** (UC-58): represented as typed links in the union link
+  graph, a separate relation index (cf. ZigZag many-to-many), or both (T16).
+- **Query-defined / reference pages** (UC-44, UC-54): a page whose canonical form is a
+  span manifest (Xanadu EDL) or a saved query (Dataview/Notion linked DB) — coordinate
+  with T16.
 
-**Inputs:** `xwiki` §2.3; `twiki` §2.3; `foswiki` §4. **UCs:** UC-34, UC-39.
+**Inputs:** `xwiki` §2.3; `twiki` §2.3; `foswiki` §4; `notion` §2–§3; `obsidian` §3;
+`shard-spectrum-synthesis` §3. **UCs:** UC-34, UC-39, UC-55, UC-58, UC-54, UC-44.
 
 **Tradeoffs:** Lossless fidelity vs a uniform queryable model; diff/search over
-structured fields vs prose.
+structured fields vs prose; one coherent model vs four content shapes.
 
 ---
 
@@ -390,15 +440,18 @@ state_hub_task_id: "6837862a-8f57-410d-9200-a6a5dcf1a7b9"
 Define how the **coordination journal** relates to an engine's native history (aligns
 with and refines T4):
 
+History is a spectrum (synthesis §2): `none → internal-only → open-file → git-native`.
+
+- **Adopt** — already git-native (Git folder/repo, Obsidian-with-Git): use as-is.
 - **Supplement** — engine history is DB-internal and non-portable
-  (Confluence, MediaWiki, XWiki `xwikircs`): the journal begins now / mirrors forward
+  (Confluence, MediaWiki, XWiki `xwikircs`, **Notion** internal page history): the
-  (UC-36).
+  journal begins now / mirrors forward (UC-36).
 - **Import** — engine history is an open file format (TWiki/yawex RCS `.txt,v`,
   Foswiki PlainFile timestamped copies): backfill into Git preserving author/timestamp
   (UC-41).
 - Authoritative journal vs mirror-reconciled-back; one-time vs continuous.
 
-**Inputs:** `xwiki` §2.4; `twiki` §2.1; `foswiki` §2.2. **UCs:** UC-36, UC-41.
+**Inputs:** `xwiki` §2.4; `twiki` §2.1; `foswiki` §2.2; `notion` §4. **UCs:** UC-36, UC-41.
 
 **Tradeoffs:** Import fidelity vs effort; duplicated history vs single source of truth.
 
@@ -415,17 +468,31 @@ state_hub_task_id: "f8835969-d118-4738-952a-5e67e5209f3d"
 
 Decide **how and where an adapter binds to a backend**:
 
-- **Dual-path attach** — runtime API vs reading the on-disk store directly
+**Three attachment modes** (synthesis §2, §3), with a backend possibly offering more
-  (consistency vs offline/fidelity); capability-gate the choice (UC-40).
+than one — so attach mode is a **per-binding, capability-gated choice**, not a fixed
-- **Hosting** — engine-side adapter via native extension API (XWiki components/REST/
+property:
-  UIX; TWiki/Foswiki plugin handlers + REST + `registerTagHandler`) vs external
+
-  adapter (no engine change, lower fidelity) (UC-38).
+- **File-store direct** — read the on-disk store as a folder shard (Obsidian vault,
+  TWiki `data/`, DokuWiki, Git repo): offline, git-native, but risks inconsistent reads
+  under a running engine (UC-40, UC-53).
+- **In-engine hosted adapter** — adapter runs *inside* the engine via its extension API
+  (XWiki components/REST/UIX; TWiki/Foswiki plugin handlers; **Roam Depot**
+  `onload/onunload` over `roamAlphaAPI`; **Obsidian plugin** over `App.vault`): high
+  fidelity, needs deploy access (UC-38, UC-50).
+- **External-API only** — attach from outside via the backend's REST API, no in-engine
+  hosting (**Notion**): full write-through without deploy access, but bounded by the
+  **operational envelope** (rate limit, eventual consistency, payload caps) and a
+  **scoped, revocable access grant** that enforces no-silent-mutation (UC-57).
+- **Dual attach** — a backend offering several modes (Obsidian: file-store *or* plugin;
+  TWiki: file *or* API): pick per binding; declare which is authoritative (UC-53).
 - **Backend-swap tolerance** — shard identity/provenance survives a storage-format
   change (Foswiki RCS↔PlainFile; folder→Git) (UC-43).
 
-**Inputs:** `twiki` §5, §6; `xwiki` §3; `foswiki` §2. **UCs:** UC-38, UC-40, UC-43.
+**Inputs:** `twiki` §5, §6; `xwiki` §3; `foswiki` §2; `roam` §5; `obsidian` §4;
+`notion` §4, §6; `shard-spectrum-synthesis` §3. **UCs:** UC-38, UC-40, UC-43, UC-50, UC-53, UC-57.
 
-**Tradeoffs:** Fidelity vs deploy access; consistency vs offline capability.
+**Tradeoffs:** Fidelity vs deploy access; consistency vs offline capability; external
+write-through vs rate-limit/eventual-consistency ceiling.
 
 ---
 
@@ -440,18 +507,71 @@ state_hub_task_id: "22b57b3a-b06b-4ff0-a34a-667a0386bf25"
 
 Specify how **non-Markdown shards** participate in the Markdown-first model:
 
+Translation is a spectrum (synthesis §2): `native → lossless → lossy-with-fidelity-report`.
+
 - Read native markup (TWiki/Foswiki TML, XWiki syntax) into the page model and accept
   Markdown overlays back via **bidirectional, lossless translation** (UC-42).
 - Feasibility proof: Foswiki **WysiwygPlugin** (TML→HTML for editing, HTML→TML
   losslessly on save).
-- **Graceful degradation:** when lossless translation is unavailable, the shard is a
+- **Lossy-with-fidelity-report** (UC-59) — for proprietary models that do *not*
-  read-only/projection participant (UC-03), never silently corrupted.
+  round-trip (**Notion** blocks/rich-text/databases; its own Markdown export is lossy):
+  translate lossily but **make fidelity loss visible** — a per-shard/per-page report of
+  what projects cleanly vs. degrades, with non-mappable elements preserved as
+  provenance/sidecar. Fidelity becomes data (union without erasure). Distinct from the
+  lossless case (UC-42).
+- **Graceful degradation:** when neither lossless nor acceptable lossy translation is
+  available, the shard is a read-only/projection participant (UC-03), never silently
+  corrupted.
 - Open: may overlays be stored in Markdown, or must they round-trip in native syntax?
 
-**Inputs:** `foswiki` §5; `twiki` §2.4; `xwiki` §2.5. **UCs:** UC-42, UC-03.
+**Inputs:** `foswiki` §5; `twiki` §2.4; `xwiki` §2.5; `notion` §3. **UCs:** UC-42, UC-59, UC-03.
 
 **Tradeoffs:** Translation coverage vs read-only floor; Markdown overlays (portable)
-vs native-syntax overlays (safe round-trip).
+vs native-syntax overlays (safe round-trip); lossy-but-usable vs read-only-but-faithful.
+
+---
+
+## Addressing, content identity, and dimensional / query navigation
+
+```task
+id: SHARD-WP-0002-T16
+status: todo
+priority: medium
+```
+
+New thread from the conceptual (Xanadu, ZigZag) + modern-tool (Roam, Notion, Obsidian/
+Dataview) dives and the synthesis (`260614-shard-spectrum-synthesis` §4). No existing
+task owns the addressing/identity/navigation layer that transclusion, overlay,
+equivalence, and dimensional views depend on. Refines T8 (transclusion/projection depth)
+and T5 (union composition); consumes T11 capabilities.
+
+- **Span addressing** — a portable sub-page address. Adopt **native span IDs** where the
+  backend mints them (Roam `:block/uid`, Notion UUID) or carries them in-file (Obsidian
+  `^id`); fall back to **content fingerprint** or path+range otherwise. Open: wrap native
+  IDs in a shard-scoped address so they survive projection and don't collide across
+  shards (Xanadu tumbler is the unreached ideal). (UC-51, UC-44.)
+- **Content identity** — detect that two pages are the same / derived content by
+  fingerprint or span-set overlap, **path-independently** — the equivalence mechanism
+  UC-27 left open. Enables reverse transclusion (UC-45). (UC-46.)
+- **Transclusion as one reference-not-copy primitive** — unify Xanadu transclusion,
+  ZigZag clone, Roam/Obsidian embed, Notion synced block over the addressable union
+  (synthesis §3). Compose-by-reference pages (UC-44) and reverse lookup (UC-45) are
+  views over it.
+- **Dimensional / query navigation** — model the union so each relationship (namespace,
+  genealogy, version, shard, equivalence, links) is a navigable **dimension** (ZigZag),
+  and a page can be **query-defined** (Dataview/Notion linked DB, UC-54). **Delegate**
+  view computation to a shard's native query engine where present (Roam Datalog, Notion
+  DB query, XWiki XWQL); else compute over the projection. (UC-47, UC-48, UC-52, UC-54.)
+- **Boundary:** this is a **derived lens over canonical files+journal**, never a new
+  store (ZigZag dive §6); the many-to-many link graph stays a graph index, not a rank.
+
+**Inputs:** `xanadu` §2–§5; `zigzag` §2–§6; `roam` §2–§4, §7; `notion` §2; `obsidian`
+§2–§3; `shard-spectrum-synthesis` §3–§5. **UCs:** UC-44, UC-45, UC-46, UC-47, UC-48,
+UC-51, UC-52, UC-54.
+
+**Tradeoffs:** Native-ID adoption (cheap, backend-coupled) vs a portable address scheme
+(harder, uniform); core navigation API vs internal organizing concept; query delegation
+(fast, backend-dependent) vs orchestrator-computed (uniform, costly).
 
 ---
 
@@ -460,13 +580,14 @@ vs native-syntax overlays (safe round-trip).
 - `spec/FederationArchitecture.md` exists with all ten federation topic sections
   (T1–T10) and an explicit **decisions / deferred / open** table per topic.
 - The **adapter contract** section of `spec/TechnicalSpecificationDocument.md` exists,
-  populated by T11–T15, with the capability vocabulary (T11) reconciled against the
+  populated by T11–T16, with the capability vocabulary (T11, the **eleven spectra**)
-  T10 federation-ops matrix.
+  reconciled against the T10 federation-ops matrix.
 - Each decision honors INTENT: mechanism over policy, union without erasure,
   overlay before mutation, no silent remote mutation, shard sovereignty,
   capability-aware adapters, Markdown-first / backend-neutral.
-- UC-26–UC-43 are traceable to architecture / adapter-contract sections
+- UC-26–UC-59 are traceable to architecture / adapter-contract sections
-  (UC-34–UC-43 to T11–T15 specifically).
+  (UC-34–UC-43 to T11–T15; UC-44–UC-59 to T11–T16 per
+  `research/260614-shard-spectrum-synthesis/findings.md` §4).
 - Conflicts or dependencies on `SHARD-WP-0001` outputs are listed (e.g.
   namespace model affects equivalent-page identity; page model T12 affects
   resolution/overlays).
@@ -484,8 +605,9 @@ vs native-syntax overlays (safe round-trip).
 5. T7 lifecycle + T8 transclusion (parallel)
 6. T9 policy catalog + T10 capability matrix (parallel, finalize doc)
 
-**Adapter contract (T11–T15)** — can start in parallel with T1; T11 first as it
+**Adapter contract (T11–T16)** — can start in parallel with T1; T11 first as it
 frames the rest, and pair it with T10 (shared capability vocabulary):
-7. T11 contract & capabilities (frames T12–T15; sync with T10)
+7. T11 contract & the eleven capability spectra (frames T12–T16; sync with T10)
 8. T12 page model + T13 history portability (parallel; T13 aligns with T4)
-9. T14 binding + T15 syntax translation (parallel, finalize adapter-contract spec)
+9. T14 binding + T15 syntax translation (parallel)
+10. T16 addressing, identity & navigation (refines T8/T5; finalize adapter-contract spec)