Add RFCs for the remaining quality-proposal ideas

Eight proposals grouped by category, each with problem statement,
concrete plan, and risks: property-based testing over the
protocol-shaped core (chunk streams, event logs, schema DSL);
mutation testing as the counterweight to the 100%-coverage gate;
deterministic tests + a universal replay-invariant fixture + nightly
race stress; architectural conformance (dependency-cruiser rules and
the LlmAdapter conformance kit); runtime arg validation at the model
boundary with a structured error taxonomy and dev-mode invariants;
doc-sync enforcement (typechecked doc snippets, API reports);
supply-chain checks and nightly vendor-drift verification against the
manifest; and deep-readonly public surfaces (logged-vs-in-flight
mutability boundary). AGENTS.md points at docs/adr and docs/rfc.

docs/rfc/006-doc-sync-and-api-reports.md

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+# RFC 006: Doc-sync enforcement and API reports
+
+Status: proposed
+
+## Problem
+
+AGENTS.md policy says docs and code must stay strictly in sync, but sync is
+verified by eyeball. Review has already caught drift twice (a cookbook
+example contradicting the type policy; a README citing the wrong
+registerAdapter call). Public API changes are similarly invisible — nothing
+makes "this commit changed the public surface" an explicit, reviewable fact.
+
+## Proposal
+
+1. **Typecheck documentation code blocks.** A script extracts fenced ```ts
+   blocks from README.md / docs/architecture.md / packages/*/README.md into a
+   temp project resolving workspace packages, and runs tsc. Blocks that are
+   intentionally elided get an explicit `ts ignore-check` info string —
+   opt-out is visible in the source. (twoslash is the fancier alternative;
+   start with plain extraction.)
+2. **Generate or verify the event-taxonomy table.** The table in
+   docs/architecture.md duplicates the `Events` declarations. Either generate
+   it from source (ts-morph walk over the `declare module 'cordis'` blocks)
+   or CI-assert that every declared event name appears in the table and vice
+   versa.
+3. **API reports.** api-extractor (or `tsc --emitDeclarationOnly` + a
+   normalized public-surface dump) producing a checked-in `etc/<pkg>.api.md`
+   per package; CI fails if regeneration differs. Every public-API change
+   becomes a diff line a reviewer (or review agent) must see.
+
+## Plan
+
+1 is a standalone script + CI step. 3 next (it also documents the surface for
+plugin authors). 2 last — verify-don't-generate is likely sufficient.
+
+## Risks
+
+Doc blocks often show fragments; the ignore-check escape hatch must stay rare
+or the gate is theater — lint the ratio if needed.