feat(p10-2): k8s-manifest-resource-v1 chunker + tier2_shared helper

Splits multi-document YAML by ^---\s*$, requires apiVersion + kind string
fields per document, emits 1 chunk per recognized k8s resource. Symbol =
<kind>/<namespace>/<name> or <kind>/<name> (cluster-scoped). Invalid YAML
returns 0 chunks (handled by p10-3 paragraph fallback). Oversize >200 lines
splits into line-windows sharing the same symbol.

tier2_shared module hosts the oversize fallback + Chunk-construction helper
mirroring code_rust_ast_v1's Chunk shape. Task E (dockerfile) and Task F
(manifest) will reuse it.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/kebab-chunk/tests/fixtures/sample_k8s.yaml

@@ -0,0 +1,34 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: api-server
+  namespace: prod
+spec:
+  replicas: 3
+  selector:
+    matchLabels:
+      app: api-server
+  template:
+    metadata:
+      labels:
+        app: api-server
+    spec:
+      containers:
+      - name: api
+        image: example/api:1.2.3
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: api-server
+  namespace: prod
+spec:
+  selector:
+    app: api-server
+  ports:
+  - port: 80
+    targetPort: 8080
+---
+# Non-k8s document — apiVersion missing
+kind: ClusterIP
+foo: bar

crates/kebab-chunk/tests/k8s_manifest_resource_v1.rs

@@ -0,0 +1,205 @@
+//! Behavioural tests for `K8sManifestResourceV1Chunker`.
+//!
+//! Documents are constructed manually (no kebab-parse-code dependency) by
+//! placing the raw YAML text into a single `Block::Code`, mirroring the
+//! pattern used in `code_rust_ast_snapshot.rs`.
+
+use std::path::PathBuf;
+
+use kebab_chunk::K8sManifestResourceV1Chunker;
+use kebab_core::{
+    AssetId, Block, CanonicalDocument, ChunkPolicy, Chunker, ChunkerVersion, CodeBlock,
+    CommonBlock, Lang, Metadata, ParserVersion, Provenance, SourceSpan, SourceType, TrustLevel,
+    WorkspacePath, id_for_block, id_for_doc,
+};
+use time::OffsetDateTime;
+
+// ── helpers ──────────────────────────────────────────────────────────────────
+
+fn fixtures_dir() -> PathBuf {
+    PathBuf::from(env!("CARGO_MANIFEST_DIR"))
+        .join("tests")
+        .join("fixtures")
+}
+
+/// Build a `CanonicalDocument` with a single `Block::Code` containing `yaml_text`.
+fn yaml_doc(yaml_text: &str) -> CanonicalDocument {
+    let wp = WorkspacePath("manifests/deploy.yaml".into());
+    let aid = AssetId("c".repeat(64));
+    let pv = ParserVersion("code-yaml-v1".into());
+    let doc_id = id_for_doc(&wp, &aid, &pv);
+
+    let line_count = yaml_text.lines().count() as u32;
+    let span = SourceSpan::Code {
+        line_start: 1,
+        line_end: line_count.max(1),
+        symbol: None,
+        lang: Some("yaml".into()),
+    };
+    let bid = id_for_block(&doc_id, "code", &[], 0, &span);
+    let block = Block::Code(CodeBlock {
+        common: CommonBlock {
+            block_id: bid,
+            heading_path: vec![],
+            source_span: span,
+        },
+        lang: Some("yaml".into()),
+        code: yaml_text.to_string(),
+    });
+
+    CanonicalDocument {
+        doc_id,
+        source_asset_id: aid,
+        workspace_path: wp,
+        title: "deploy.yaml".into(),
+        lang: Lang("und".into()),
+        blocks: vec![block],
+        metadata: Metadata {
+            aliases: vec![],
+            tags: vec![],
+            created_at: OffsetDateTime::from_unix_timestamp(1_700_000_000).unwrap(),
+            updated_at: OffsetDateTime::from_unix_timestamp(1_700_000_000).unwrap(),
+            source_type: SourceType::Note,
+            trust_level: TrustLevel::Primary,
+            user_id_alias: None,
+            user: Default::default(),
+            repo: Some("kebab".into()),
+            git_branch: Some("main".into()),
+            git_commit: Some("0".repeat(40)),
+            code_lang: Some("yaml".into()),
+        },
+        provenance: Provenance { events: vec![] },
+        parser_version: pv,
+        schema_version: 1,
+        doc_version: 1,
+        last_chunker_version: None,
+        last_embedding_version: None,
+    }
+}
+
+fn policy() -> ChunkPolicy {
+    ChunkPolicy {
+        target_tokens: 500,
+        overlap_tokens: 80,
+        respect_markdown_headings: false,
+        chunker_version: ChunkerVersion("k8s-manifest-resource-v1".into()),
+    }
+}
+
+// ── tests ─────────────────────────────────────────────────────────────────────
+
+/// Three YAML documents: 2 valid k8s resources + 1 non-k8s (no apiVersion).
+/// The chunker must emit exactly 2 chunks with the correct symbols and lang.
+#[test]
+fn k8s_multi_doc_emits_one_chunk_per_resource() {
+    let fixture_path = fixtures_dir().join("sample_k8s.yaml");
+    let text = std::fs::read_to_string(&fixture_path)
+        .unwrap_or_else(|e| panic!("cannot read fixture {}: {e}", fixture_path.display()));
+
+    let doc = yaml_doc(&text);
+    let chunks = K8sManifestResourceV1Chunker
+        .chunk(&doc, &policy())
+        .expect("chunk");
+
+    assert_eq!(
+        chunks.len(),
+        2,
+        "expected 2 k8s chunks, got {}: {chunks:#?}",
+        chunks.len()
+    );
+
+    let symbols: Vec<&str> = chunks
+        .iter()
+        .map(|c| {
+            match &c.source_spans[0] {
+                SourceSpan::Code { symbol, .. } => {
+                    symbol.as_deref().expect("symbol must be Some for k8s chunks")
+                }
+                other => panic!("expected Code span, got {other:?}"),
+            }
+        })
+        .collect();
+
+    assert_eq!(
+        symbols,
+        vec!["Deployment/prod/api-server", "Service/prod/api-server"],
+        "symbols mismatch: {symbols:?}"
+    );
+
+    // Verify lang = "yaml" on every chunk.
+    for chunk in &chunks {
+        match &chunk.source_spans[0] {
+            SourceSpan::Code { lang, .. } => {
+                assert_eq!(lang.as_deref(), Some("yaml"), "lang must be 'yaml'");
+            }
+            other => panic!("expected Code span, got {other:?}"),
+        }
+    }
+
+    // Verify chunker_version label.
+    for chunk in &chunks {
+        assert_eq!(chunk.chunker_version.0, "k8s-manifest-resource-v1");
+    }
+}
+
+/// A YAML document with an indentation error (tab in a space-indented context)
+/// must cause the chunker to return 0 chunks for the entire file.
+#[test]
+fn k8s_invalid_yaml_emits_zero_chunks() {
+    // serde_yaml 0.9 is lenient about duplicate keys (last wins), so use a
+    // genuine YAML structural error (unclosed flow sequence) to force a parse
+    // failure.
+    let actually_bad = "apiVersion: v1\nkind: Service\nfoo: [\nbar\n";
+
+    let doc = yaml_doc(actually_bad);
+    let chunks = K8sManifestResourceV1Chunker
+        .chunk(&doc, &policy())
+        .expect("chunk should not error — return Ok(vec![]) for invalid yaml");
+
+    assert_eq!(
+        chunks.len(),
+        0,
+        "invalid YAML must yield 0 chunks, got {}: {chunks:#?}",
+        chunks.len()
+    );
+}
+
+/// A cluster-scoped resource (no `metadata.namespace`) must produce a symbol
+/// of the form `<Kind>/<name>` (two components, no namespace segment).
+#[test]
+fn k8s_cluster_scoped_resource_symbol() {
+    let yaml = "\
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRole
+metadata:
+  name: cluster-admin
+rules:
+- apiGroups: [\"*\"]
+  resources: [\"*\"]
+  verbs: [\"*\"]
+";
+
+    let doc = yaml_doc(yaml);
+    let chunks = K8sManifestResourceV1Chunker
+        .chunk(&doc, &policy())
+        .expect("chunk");
+
+    assert_eq!(
+        chunks.len(),
+        1,
+        "expected 1 chunk for cluster-scoped resource, got {}: {chunks:#?}",
+        chunks.len()
+    );
+
+    match &chunks[0].source_spans[0] {
+        SourceSpan::Code { symbol, lang, .. } => {
+            assert_eq!(
+                symbol.as_deref(),
+                Some("ClusterRole/cluster-admin"),
+                "cluster-scoped symbol must be <Kind>/<name>"
+            );
+            assert_eq!(lang.as_deref(), Some("yaml"));
+        }
+        other => panic!("expected Code span, got {other:?}"),
+    }
+}