Phase 0: lock platform contract, naming convention, and style enforcement

Establishes the framework's foundation as a multi-site adoptable platform.

ADRs (migrations/adr/):
- ADR-001 (ACCEPTED): Asset is the platform contract; Machine retires.
  Three relationship types (partof, controls, connectedto) with free-text
  label, position-resolution chain (asset > related > location),
  hierarchical locations, sibling-bay propagation.
- ADR-002 (ACCEPTED): Plugin contract semver via __contract_version__.
- ADR-003 (ACCEPTED): Hybrid plugin distribution (in-tree bundled +
  filesystem-based external).
- ADR-004 (ACCEPTED): Per-site instances, not multi-tenant.
- ADR-005 (ACCEPTED): Equipment plugin (manufacturing) split from
  measuringtools plugin (metrology). Subtype-table pattern for protocol
  data (FOCAS, CLM, MTConnect).
- ADR-006 (ACCEPTED): Plugin collector contract via get_collector_schema
  hook with API-key auth and identity-based upsert.

Naming convention v1 (CONTRIBUTING.md):
- DB tables/columns: lowercase concatenated, no underscores or dashes
- DB-mirrored Python/JS variables match column names exactly; pure code
  follows host-language convention (PEP 8 / camelCase)
- Closed acronym allowlist (universal + shop-floor domain), banned
  shorthand list with suffix exception (printers_bp etc allowed)
- Plain ASCII everywhere: chat, docs, comments, string literals

Style enforcement (scripts/check-naming-and-style.sh):
- Pre-commit-runnable check script: non-ASCII, banned shorthand,
  snake_case DB names, snake_case API params in frontend
- Fixes 14 violations across 11 files (Unicode arrows, snake_case
  params, ctx -> canvasContext, res -> response, req -> request_obj)

Project state (CLAUDE.md, README.md, frontend/CLAUDE.md):
- De-staled CLAUDE.md to reflect actual current state
- README unifies DB story (MySQL canonical, SQLite test-only)
- frontend/CLAUDE.md points at root convention

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

migrations/adr/ADR-002-plugin-versioning.md

@@ -0,0 +1,60 @@
+# ADR-002: Plugin contract versioning
+
+- **Status:** ACCEPTED
+- **Date:** 2026-05-08
+- **Deciders:** cproudlock
+- **Supersedes:** none
+
+## Context
+
+Once sister sites start writing their own plugins (or pulling community plugins), the framework's plugin contract becomes a public API. Without a versioning story, any change to `BasePlugin` or the core platform models can silently break installed plugins at remote sites.
+
+The existing `BasePlugin` and `PluginMeta` already declare a `core_version` field (default `">=1.0.0"`), but it is not enforced anywhere. The plugin loader does not check it before instantiation.
+
+## Decision
+
+The framework adopts **semantic versioning for the plugin contract**, declared in two places:
+
+1. **Framework version** (`shopdb/__init__.py`): a single `__contract_version__` constant. This is the version of the platform contract as defined in ADR-001. Bumped according to semver:
+   - **Major**: breaking change to `BasePlugin` ABC, `PluginMeta` schema, or any model in the platform contract (`Asset`, `AssetType`, `AssetStatus`, `AssetRelationship`, `Vendor`, `Location`, `BusinessUnit`, `Model`, `OperatingSystem`).
+   - **Minor**: additive change (new optional hook, new field on a contract model with default).
+   - **Patch**: bug fix, no contract surface change.
+2. **Plugin requirement** (`plugins/<name>/manifest.json`): the existing `core_version` field, expressed as a semver range (e.g., `">=1.0.0,<2.0.0"`).
+
+The plugin loader (`shopdb/plugins/loader.py`) checks `core_version` against `__contract_version__` at load time. Mismatch in dev = re-raise (fail loud). Mismatch in prod = log error, mark plugin as incompatible, exclude from registration.
+
+The `__contract_version__` starts at **`1.0.0`** when ADR-001 is accepted and the `Machine` retirement migration is complete (whichever comes later). Until then, the framework is pre-1.0; plugins should declare `core_version: ">=0.1.0,<1.0.0"`.
+
+## Consequences
+
+### Positive
+
+- Sister sites can pin a known-good framework version. They will not be silently broken when the framework is upgraded.
+- Plugin authors know what counts as a breaking change because the contract surface is enumerated in ADR-001.
+- The loader fails predictably: a mismatched plugin is reported, not silently disabled.
+
+### Negative / cost
+
+- Discipline required: every change to the contract surface must be classified (major / minor / patch). Adding a `version-bump` skill (or a check in code review) reduces the chance of mis-classification.
+- `__contract_version__` becomes a coupling point. Forgetting to bump it after a breaking change means downstream plugins crash silently at runtime instead of failing at install.
+
+### Neutral
+
+- Existing plugins (`plugins/printers/`, etc.) ship as part of the framework, so their `core_version` is always the current `__contract_version__`. The discipline matters mostly for external / sister-site plugins.
+
+## Alternatives considered
+
+1. **No versioning, just trust.** Works for an in-tree-only world. Fails the moment a sister site ships its own plugin. Rejected.
+2. **Calendar versioning** (e.g., `2026.05.0`). Easier to bump, harder to communicate breaking changes. Rejected; semver is the industry standard for library-like contracts.
+3. **Per-hook versioning.** Each hook has its own version. Too granular; plugins still couple to multiple hooks. Rejected.
+
+## Open questions
+
+- When does the framework declare `1.0.0`? Tied to ADR-001 (Asset retirement of Machine) and the framework being deemed "ready for sister sites". Best-effort target: end of Phase 5 in the refactor plan.
+- Should `core_version` accept commercial-grade ranges (`^1.0.0`) or stick to PEP 440 / npm-style ranges? Recommend pip-style (`>=,<`) to match Python ecosystem.
+
+## References
+
+- `shopdb/plugins/base.py` (PluginMeta declaration)
+- `shopdb/plugins/loader.py` (where the version check belongs)
+- ADR-001 (defines what is in the contract)