feat(ogar-adapter-ttl): scaffold Turtle (RDF/OWL) adapter — Phase 2a

.github/workflows/ci.yml

@@ -42,3 +42,8 @@ jobs:
       # self-describing-registry loop (ADR-023 receipt).
       - name: cargo test -p ogar-knowable-from --features surrealql-hint
         run: cargo test -p ogar-knowable-from --features surrealql-hint
+      # Exercise the `ttl-parser` feature on ogar-adapter-ttl — pulls
+      # in oxttl / oxrdf for Turtle parsing. The emit path is feature-
+      # free, but the round-trip tests need the parser.
+      - name: cargo test -p ogar-adapter-ttl --features ttl-parser
+        run: cargo test -p ogar-adapter-ttl --features ttl-parser

Cargo.toml

@@ -7,6 +7,7 @@ members = [
     "crates/ogar-adapter",
     "crates/ogar-proposal",
     "crates/ogar-adapter-surrealql",
+    "crates/ogar-adapter-ttl",
     "crates/ogar-knowable-from",
 ]
 

crates/ogar-adapter-ttl/Cargo.toml

@@ -0,0 +1,31 @@
+[package]
+name = "ogar-adapter-ttl"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+repository.workspace = true
+authors.workspace = true
+rust-version.workspace = true
+description = "Bidirectional Turtle (RDF/OWL) bridge for OGAR. emit_ttl(Class, prefix) renders a canonical OGAR Turtle document by composing ogar-emitter's TripleEmitter output; parse_ttl (behind the `ttl-parser` feature) consumes Turtle via oxttl and lifts back into Vec<Class>. Companion to ogar-adapter-surrealql; together they cover the Morris-syntax axis for OGAR's two canonical wire formats (per docs/RDF-OWL-ALIGNMENT.md Phase 2a)."
+
+[features]
+default = []
+serde = ["dep:serde", "ogar-vocab/serde"]
+# Enable Turtle parsing (oxttl). Emit is feature-free — it's a
+# straightforward Turtle serialization of ogar-emitter::TripleEmitter
+# triples. Parsing requires the full oxttl streaming parser.
+ttl-parser = ["dep:oxttl", "dep:oxrdf"]
+
+[dependencies]
+ogar-vocab = { path = "../ogar-vocab" }
+ogar-emitter = { path = "../ogar-emitter" }
+ogar-ontology = { path = "../ogar-ontology" }
+serde = { workspace = true, optional = true }
+# Wired under the `ttl-parser` feature. oxttl is the oxigraph project's
+# streaming Turtle/N-Triples/N-Quads/TriG parser — pure Rust, RFC-
+# compliant, low dep footprint. oxrdf gives the typed Term/Triple
+# values oxttl yields.
+oxttl = { version = "0.2", optional = true }
+# oxrdf 0.3 matches oxttl 0.2.3's transitive version — both must
+# agree or Term/Subject types collide at the lift seam.
+oxrdf = { version = "0.3", optional = true }