spec: extract use cases from wiki-engines landscape research (UC-34–UC-37)

Mine the one research dir not yet promoted (260608-wikiengines-overview) into
the catalog. Adds four heterogeneous-backend attachment scenarios the other
research didn't surface:

- UC-34 attach structured/semantic shard without lossy flattening (SMW, XWiki)
- UC-35 attach shard with coarse write granularity (TiddlyWiki single-file)
- UC-36 supply git-addressable history to internal-history engine (Confluence)
- UC-37 attach static export as read-only backup shard (MediaWiki dump)

Adds a `wikiengines` source token + traceability column and a wikiengines
mapping subsection. The scan mostly reinforced existing UCs and the L0→L4
ladder; its main yield is adapter-contract constraints tracked in SHARD-WP-0002.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
2026-06-13 18:39:30 +02:00
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@@ -1,9 +1,10 @@
# UseCaseCatalog
Status: **draft** · Date: 2026-06-08 · Updated: 2026-06-08
Status: **draft** · Date: 2026-06-08 · Updated: 2026-06-13
Promoted from `research/260608-c2-wiki-origins/`,
`research/260608-yawex-prior-art/`, and `research/260608-federation-concepts/`.
`research/260608-yawex-prior-art/`, `research/260608-federation-concepts/`, and
`research/260608-wikiengines-overview/`.
See InfoTechPrimers on coulomb.social for use-case catalog conventions.
## Conventions
@@ -12,7 +13,7 @@ Each use case lists:
- **Actor** — who initiates the action
- **Goal** — observable outcome
- **Source** — research lineage (`c2`, `yawex`, `federation`, `intent`, or combined)
- **Source** — research lineage (`c2`, `yawex`, `federation`, `wikiengines`, `intent`, or combined)
- **Notes** — shard-wiki-specific constraints or open design points
Priority hints: **MVP** = likely early value; **Later** = important but not first slice.
@@ -175,6 +176,58 @@ divergent information space without destroying the original.
Space-level fork — distinct from UC-26 page-level fork.
**Priority:** Later
### UC-34 — Attach a structured or semantic shard without lossy flattening
**Actor:** Maintainer
**Goal:** Attach an engine whose pages carry structured or queryable data beyond
Markdown (Semantic MediaWiki annotations, XWiki objects/forms) and project it
without silently discarding the structure.
**Source:** wikiengines, intent
**Notes:** Engine scan shows "wiki page" spans flat Markdown to queryable
knowledge objects. Markdown-first must **degrade gracefully**, not flatten:
needs a passthrough / sidecar-metadata / provenance escape hatch. Page-model
question deferred to `SHARD-WP-0002` (findings §6 Q1). Distinct from UC-02
(assumes Markdown-shaped pages).
**Priority:** Later
### UC-35 — Attach a shard with coarse write granularity
**Actor:** Maintainer
**Goal:** Attach a backend whose unit of write is not the page — a single-file
wiki (TiddlyWiki) or a whole-space/DB-transaction engine — and have shard-wiki
respect that granularity instead of assuming per-page writes.
**Source:** wikiengines, intent
**Notes:** Capability-aware adapters: the **capability profile must encode write
granularity** (per-page / per-file / per-space / append-only). Overlay and
patch flows must adapt (findings §5 #1). Affects conflict scope and locking.
**Priority:** Later
### UC-36 — Supply a git-addressable history to an internal-history engine
**Actor:** Maintainer
**Goal:** Attach an engine whose revisions live only in its own database
(Confluence, MediaWiki) and give the information space a portable, git-backed
history it otherwise lacks.
**Source:** wikiengines, intent
**Notes:** Many engines expose revisions but not portable, git-style history.
The **coordination journal** supplies the Git-addressable layer (INTENT). Open:
is the journal authoritative or a mirror reconciled back to the engine
(findings §6 Q3)? Complements UC-07 divergence and UC-24 provenance.
**Priority:** Later
### UC-37 — Attach a static engine export as a read-only backup shard
**Actor:** Maintainer
**Goal:** Attach a one-shot export with no live origin — a MediaWiki XML dump, an
HTML mirror, or an archived/read-only C2 — as a read-only cache/backup/patch
target.
**Source:** wikiengines, intent
**Notes:** Graceful degradation — a frozen export is still a legitimate
participant. Distinct from UC-03 (live projection with a reachable origin) and
UC-28 (carry pages *forward* into a new space); here the dump itself is the
shard. Read-only mode in `spec/ArchitectureBlueprint.md`.
**Priority:** Later
---
## B. Knowledge work and collaboration
@@ -370,23 +423,27 @@ CamelCase and `[[free links]]`. Markdown-first link semantics TBD.
## Traceability
| UC | c2 research | yawex research | federation research | INTENT |
|----|-------------|----------------|---------------------|--------|
| UC-01 | ✓ | | | ✓ |
| UC-02 | | ✓ | | ✓ |
| UC-03 | | ✓ | ✓ | ✓ |
| UC-04 | ✓ | ✓ | ✓ | ✓ |
| UC-05 | ✓ | ✓ | ✓ | ✓ |
| UC-06 | | ✓ | | ✓ |
| UC-07 | | | ✓ | ✓ |
| UC-26 | | | ✓ | ✓ |
| UC-27 | | | ✓ | ✓ |
| UC-28 | | | ✓ | |
| UC-29 | | | ✓ | ✓ |
| UC-30 | | | ✓ | |
| UC-31 | | | ✓ | ✓ |
| UC-32 | | | ✓ | ✓ |
| UC-33 | | | ✓ | ✓ |
| UC | c2 research | yawex research | federation research | wikiengines research | INTENT |
|----|-------------|----------------|---------------------|----------------------|--------|
| UC-01 | ✓ | | | | ✓ |
| UC-02 | | ✓ | | | ✓ |
| UC-03 | | ✓ | ✓ | | ✓ |
| UC-04 | ✓ | ✓ | ✓ | | ✓ |
| UC-05 | ✓ | ✓ | ✓ | | ✓ |
| UC-06 | | ✓ | | | ✓ |
| UC-07 | | | ✓ | | ✓ |
| UC-26 | | | ✓ | | ✓ |
| UC-27 | | | ✓ | | ✓ |
| UC-28 | | | ✓ | | |
| UC-29 | | | ✓ | | ✓ |
| UC-30 | | | ✓ | | |
| UC-31 | | | ✓ | | ✓ |
| UC-32 | | | ✓ | | ✓ |
| UC-33 | | | ✓ | | ✓ |
| UC-34 | | | | ✓ | ✓ |
| UC-35 | | | | ✓ | ✓ |
| UC-36 | | | | ✓ | ✓ |
| UC-37 | | | | ✓ | ✓ |
| UC-08 | ✓ | | |
| UC-09 | ✓ | | |
| UC-10 | ✓ | | |
@@ -448,6 +505,21 @@ CamelCase and `[[free links]]`. Markdown-first link semantics TBD.
| UC-FED-07 Transclude remote span | UC-32 |
| UC-FED-08 Git-branch information space | UC-33 |
### wikiengines mapping
| Engine-landscape finding | Catalog UC |
|--------------------------|------------|
| Structured/semantic engines (Semantic MediaWiki, XWiki) — pages as queryable objects | UC-34 |
| Coarse write granularity (TiddlyWiki single-file; whole-space DB writes) | UC-35 |
| Internal-only revision history (Confluence, MediaWiki) needs portable git history | UC-36 |
| Static exports / read-only archives (MediaWiki XML dump, archived C2, HTML mirror) | UC-37 |
Note: the scan mostly **reinforced** existing UCs and the L0→L4 ladder rather than
adding scenarios — its primary yield is adapter-contract constraints
(`research/260608-wikiengines-overview/findings.md` §3, §5), tracked in
`workplans/SHARD-WP-0002-federation-architecture.md`. UC-34UC-37 are the
genuinely new attachment scenarios it surfaced.
---
## Open questions