spec(SHARD-WP-0002): fold adapter-contract constraints into T11-T15

Distill the cross-cutting adapter-contract constraints from the four engine
deep dives (wiki-engines landscape, XWiki, TWiki, Foswiki) into five concrete
design tasks, complementing the federation tasks (T1-T10):

- T11 adapter contract: capability model & versioned interface (Foswiki::Store
  prior art; write-granularity as a capability dimension)
- T12 page model: structured/typed payload representation (XObjects, %META%,
  multi-record, bodiless pages)
- T13 history portability: supplement (DB-internal) vs import (open file history)
- T14 adapter binding: attach path, engine-hosted vs external, backend-swap
- T15 syntax translation & content fidelity (non-Markdown round-trip)

Adds an adapter-contract decision-topics table, cross-links T10<->T11 on the
shared capability vocabulary, and updates context/acceptance/task-order. Tasks
registered in the state hub (workstream 2af4c46d).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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2026-06-13 23:35:09 +02:00
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@@ -8,7 +8,7 @@ status: active
owner: tegwick
topic_slug: whynot
created: "2026-06-08"
updated: "2026-06-08"
updated: "2026-06-13"
depends_on:
- SHARD-WP-0001
state_hub_workstream_id: "2af4c46d-cbfd-40ea-a94b-d9e60b0f9945"
@@ -27,11 +27,27 @@ UC-26UC-33.
Primary deliverable: `spec/FederationArchitecture.md` (created and filled by
this workplan's tasks).
Secondary deliverable (T11T15, added 2026-06-13): the **shard adapter contract**
constraints distilled from the engine deep dives, 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.
## Context
- Research: `research/260608-federation-concepts/findings.md`
- Use cases: `spec/UseCaseCatalog.md` § A (UC-26UC-33)
- Aspiration: `INTENT.md` (orchestrator, not engine; mechanism over policy)
- Federation research: `research/260608-federation-concepts/findings.md`
- Engine deep dives (adapter-contract inputs, T11T15):
- `research/260608-wikiengines-overview/findings.md` (landscape; capability
heterogeneity, write granularity)
- `research/260613-xwiki-deep-dive/findings.md` (DB/component app-platform)
- `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-26UC-43; UC-3443 are the
engine-attachment / adapter-contract 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,
provenance — federation architecture must align with, not duplicate, those
outputs)
@@ -54,6 +70,16 @@ decision records only.
| Consensus presets | Spread, merge, designated canonical — policy not core | UC-07, UC-27 |
| Capability matrix | Which federation ops require which adapter capabilities | UC-02UC-07 |
### Adapter-contract topics (T11T15, from engine deep dives)
| Topic | Key tradeoff | Primary UCs |
|-------|--------------|-------------|
| Adapter contract & capabilities | Versioned interface + capability vocabulary; write granularity | UC-02, UC-35, UC-38 |
| Structured page model | Typed frontmatter vs sidecar vs blob; bodiless / multi-record pages | UC-34, UC-39 |
| History portability | Supplement (DB-internal) 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 |
| Syntax translation | Lossless non-Markdown round-trip vs read-only degradation | UC-42, UC-03 |
---
## Architecture positioning and boundaries
@@ -281,28 +307,185 @@ Cross-check against INTENT capability-aware adapters principle. Identify
graceful degradation paths for limited backends (read-only participant,
projection-only, patch target).
Feeds `spec/TechnicalSpecificationDocument.md` adapter contract section.
This matrix **consumes the capability vocabulary defined in T11** — keep the two
in sync. Feeds `spec/TechnicalSpecificationDocument.md` adapter contract section.
---
# Shard adapter contract (folded from engine deep dives, 2026-06-13)
These tasks distill the cross-cutting **adapter-contract constraints** surfaced by
the four engine deep dives (wiki-engines landscape, XWiki, TWiki, Foswiki). They
answer *what a backend must expose to participate as a shard*, complementing the
federation tasks above (which answer *what the union does*). Output target:
`spec/TechnicalSpecificationDocument.md` (adapter contract section), cross-linked
from `spec/FederationArchitecture.md`.
Recurring cross-engine insight to honor: **structure and history in text files
federate far more easily than in a database**, and **Foswiki::Store already proves
the versioned-interface-with-swappable-backends pattern** the contract should adopt.
## Adapter contract: capability model & versioned interface
```task
id: SHARD-WP-0002-T11
status: todo
priority: high
state_hub_task_id: "a7379621-6694-488b-94ca-846b8e27e745"
```
Define the **capability-aware shard adapter contract** as a *versioned* interface,
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,
transclude-source, translate-syntax, structured-payload` (reconcile with T10).
- **Write granularity** as a first-class capability dimension: per-page / per-file /
per-space / append-only (TiddlyWiki single-file vs DB whole-space vs TWiki per-topic).
- Versioning/compatibility rules for the contract itself; capability discovery.
**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.
**Tradeoffs:** Rich capability set (precise degradation) vs contract complexity;
static profile vs runtime capability negotiation.
---
## Page model: structured / typed payload representation
```task
id: SHARD-WP-0002-T12
status: todo
priority: high
state_hub_task_id: "7334a4a4-ba75-4fac-a8b4-8350d342b299"
```
Decide how the **backend-neutral, Markdown-first page model carries structured data
without flattening**:
- 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.
- Representation choice: typed frontmatter vs sidecar file vs opaque provenance blob.
- **Bodiless pages** (UC-39): may a page be purely structured, no Markdown body?
- **N typed records per page** (not one form) must be representable.
**Inputs:** `xwiki` §2.3; `twiki` §2.3; `foswiki` §4. **UCs:** UC-34, UC-39.
**Tradeoffs:** Lossless fidelity vs a uniform queryable model; diff/search over
structured fields vs prose.
---
## History portability: supplement vs import
```task
id: SHARD-WP-0002-T13
status: todo
priority: high
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):
- **Supplement** — engine history is DB-internal and non-portable
(Confluence, MediaWiki, XWiki `xwikircs`): the 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.
**Tradeoffs:** Import fidelity vs effort; duplicated history vs single source of truth.
---
## Adapter binding: attach path, hosting, backend-swap
```task
id: SHARD-WP-0002-T14
status: todo
priority: medium
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
(consistency vs offline/fidelity); capability-gate the choice (UC-40).
- **Hosting** — engine-side adapter via native extension API (XWiki components/REST/
UIX; TWiki/Foswiki plugin handlers + REST + `registerTagHandler`) vs external
adapter (no engine change, lower fidelity) (UC-38).
- **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.
**Tradeoffs:** Fidelity vs deploy access; consistency vs offline capability.
---
## Syntax translation & content fidelity
```task
id: SHARD-WP-0002-T15
status: todo
priority: medium
state_hub_task_id: "22b57b3a-b06b-4ff0-a34a-667a0386bf25"
```
Specify how **non-Markdown shards** participate in the Markdown-first model:
- 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
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.
**Tradeoffs:** Translation coverage vs read-only floor; Markdown overlays (portable)
vs native-syntax overlays (safe round-trip).
---
## Acceptance criteria
- `spec/FederationArchitecture.md` exists with all ten topic sections and an
explicit **decisions / deferred / open** table per topic.
- `spec/FederationArchitecture.md` exists with all ten federation topic sections
(T1T10) and an explicit **decisions / deferred / open** table per topic.
- The **adapter contract** section of `spec/TechnicalSpecificationDocument.md` exists,
populated by T11T15, with the capability vocabulary (T11) 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.
- UC-26UC-33 are traceable to architecture sections.
overlay before mutation, no silent remote mutation, shard sovereignty,
capability-aware adapters, Markdown-first / backend-neutral.
- UC-26UC-43 are traceable to architecture / adapter-contract sections
(UC-34UC-43 to T11T15 specifically).
- Conflicts or dependencies on `SHARD-WP-0001` outputs are listed (e.g.
namespace model affects equivalent-page identity).
namespace model affects equivalent-page identity; page model T12 affects
resolution/overlays).
- `SHARD-WP-0001` and `SHARD-WP-0002` can proceed in parallel where topics
are independent; merge conflicts in spec are resolved before implementation
workplan starts.
## Suggested task order
**Federation architecture (T1T10):**
1. T1 positioning (frames everything)
2. T2 remix primitives + T3 equivalent identity (parallel)
3. T4 history model
4. T5 composition + T6 notification (parallel)
5. T7 lifecycle + T8 transclusion (parallel)
6. T9 policy catalog + T10 capability matrix (parallel, finalize doc)
6. T9 policy catalog + T10 capability matrix (parallel, finalize doc)
**Adapter contract (T11T15)** — 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 T12T15; 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)