Keep the shared derived index and single unit-of-work

Context¶

docir compiles markdown into one derived SQLite index (metadata + FTS5 + relation graph + embeddings) plus the canonical files, and mutates them in a single unit-of-work so a write and its index update are atomic. A strict reading of ARCHITECTURE_RULES §5.1/§5.3 forbids sharing a transaction across modules and requires each table to have exactly one owning module. Fully honoring that would mean per-module storage and event-driven, eventually-consistent cross-module consistency — a large rewrite of working, tested software with real regression risk, for a single-user local tool where the atomic write is a feature.

Decision¶

Keep the single shared SQLite schema, the shared UnitOfWork, and the shared file stores. House them in platform/persistence and platform/filesystem. Because their repositories and stores map each context's domain entities, they depend on modules/<context>/domain. Declare exactly these edges in tach.toml as deprecated = true: they are the initial ratchet baseline (§8.1, §12.1), reported on every run and allowed only to shrink. Modules never share a transaction through each other's code — all shared-data access goes through platform, which keeps the module graph acyclic (tags → documents → indexing).

Consequences¶

• Easier: atomic writes; a small, well-understood persistence layer; no event bus or idempotency machinery to maintain.
• Harder: platform is not a pure leaf; the baseline edges must be watched so they do not grow.
• Now forbidden (by the ratchet): any NEW platform → module edge, or any new cross-module transaction coupling. Shrinking the baseline — by splitting the index per module behind events — is the sanctioned future direction, and would supersede this ADR.