decide: keep+isolate or delete OCaml `Choreographic Sessions` sub-project at `src/{ast,lexer,parser,typecheck}.ml{,l,y}`

[hyperpolymath]

Finding

A complete OCaml project lives inside the Rust workspace's src/ directory and is never referenced from any canonical doc (README, STATUS, EXPLAINME, CLAUDE.md, PROOF-NEEDS).

Files:

• src/ast.ml (header: "Ephapax AST - Extended with Choreographic Sessions")
• src/lexer.ml, src/lexer.mll
• src/parser.ml, src/parser.mli, src/parser.mly
• src/typecheck.ml
• src/ast.cmi, src/ast.cmo, src/parser.cmi, src/typecheck.cmi, src/typecheck.cmo (build artefacts checked in)
• test_minimal.ml + .cmi + .cmo at repo root mirroring the session_decl record from ast.ml
• test/test_choreo.eph + test/test_typecheck.ml in a test/ (singular) directory parallel to the standard tests/ (plural) — shadowing

Workspace Cargo.toml has no link to any of these files; they're outside the Rust build entirely.

Three options

A. Salvage to research dir: move under research/choreographic-sessions/ with its own README + decision note explaining scope/status; add gitignore for .cmi/.cmo.

B. Delete entirely: git rm all of the above. The files are unreferenced; if salvage is desired the git history preserves them.

C. Promote to first-class subdirectory if Choreographic Sessions is an active research workstream that should be in the canonical docs.

Severity

Blocker per the meander audit (#69) — clutters src/ for any agent reading it as the Rust source root, and the build artefacts are git-tracked debris.

Companion findings (separate issues recommended)

• lib/formatter.rs + lib/linter.rs are orphan Rust files at top-level lib/ not referenced by any Cargo.toml; duplicates exist at src/ephapax-tools/src/{formatter,linter,documenter}.rs.
• src/ephapax-tools/ is a Rust crate with Cargo.toml referencing workspace deps but is NOT in the workspace members list.

Discovered: 2026-06-01 comprehensive meander audit.