Iteration 3 — compiler front (`woc`)

Format: fiberloom product/story-iteration-template. Part of Story — one language, one runtime, one database, one binary.

Goals

An OCaml, stdlib-only compiler front end: .wo source becomes a typed AST with ownership annotations, or plain, precise diagnostics — the half of the language the developer converses with.
Ownership errors read like sentences naming both sites ("moved at pricing.wo:14, used at pricing.wo:17") — the ergonomics bet that makes MVS beat Rust for this audience.

What to achieve?
- Given the pricing-demo classes,
- when woc runs its front pipeline (lex → parse → typecheck → ownership),
- then --dump-ast output matches the golden file and zero diagnostics are emitted.
What to achieve?
- Given a file violating ownership rules (move-after-use, borrow escape, double exclusive borrow),
- when it compiles,
- then each violation reports a stable WO-E### code with both source sites, and one bad declaration does not stop diagnosis of the rest of the file.
What to achieve?
- Given a class that satisfies an interface structurally,
- when typechecking runs,
- then satisfaction is recognized with no implements declaration, and per-method self mutability is inferred (reads shared, writes exclusive).

Newline-significant lexing and the identifier gotchas mirror crates/rt's lexer — grammar parity is a stated contract.
Architecture map: compiler/plan/architecture.md (pipeline, module contracts, study references).

Execute the existing plan: compiler/plan/2026-08-01-woc-compiler-front.md (diagnostics module, lexer, declaration/statement/expression parsers with skip-on-block, typechecker with field-kind derivation, MVS ownership pass producing the four emitter tables, driver + error catalog).