refactor(app): extract dispatch polymorphism — App.extract_for(...) + 11 Extractor registry

kebab-app 의 hardcoded extract dispatch (`ImageExtractor` + `PdfTextExtractor` + 9 AST `*Extractor` 의 `::new().extract(…)` callsite 11곳 + 9 AST arm match) 를 `App::extract_for(&MediaType, &ExtractContext, &[u8])` 단일 polymorphic call 로 통합. trait 변경 0, parser source 변경 0, wire schema 변경 0 (success path).

핵심 변경:
- App struct 에 `pub(crate) extractors: Vec<Box<dyn Extractor + Send + Sync>>` field + `pub(crate) fn extract_for(...)` helper method.
- App::open_with_config 의 registry init = 11 Extractor (image + pdf + 9 AST).
- ImagePipeline struct 의 `extractor: &'a ImageExtractor` field 제거 + lib.rs:356 local + lib.rs:1235 alias 삭제 (atomic block).
- 9 AST arm (lib.rs:2012-2047 의 12 arm = 11 explicit + 1 wildcard) → 4 arm (9 AST grouped + 7 manifest + 1 shell + 1 other-bail).
- in-crate unit test (app.rs 의 `mod tests_extractor_dispatch`) 3 class: registry length 11 / mutually-exclusive supports() grid (16 sample MediaType) / extract_for error path (Audio).

scope = AST 9-arm + image + pdf extract callsite only. MarkdownExtractor / Tier 2/3 / outer 4-arm / inner 4 match / Chunker dispatch 모두 future-defer (별 PR — spec §11).

Wire schema (success path) 변경 0 — ingest_report.v1 / search_response.v1 / answer.v1 byte-identical (4-medium SMOKE 비교 검증). error.v1.message 의 internal context string wording 변경 (예: `kb-parse-image::ImageExtractor::extract` → `kb-app::extract_for (image)`) 은 spec §5.5 risk acceptance — `error.v1.code` + `error.v1.schema_version` 보존, user-visible surface 외. Cargo workspace.version bump 0.

Refs:
- docs/superpowers/specs/2026-05-26-extractor-dispatch-unification-spec.md (2 round APPROVE)
- docs/superpowers/plans/2026-05-26-extractor-dispatch-unification-plan.md (3 round APPROVE)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

crates/kebab-app/src/app.rs

@@ -40,11 +40,18 @@ use anyhow::{Context, Result, anyhow};
 use lru::LruCache;
 
 use kebab_core::{
-    Answer, DocumentStore, Embedder, IndexVersion, LanguageModel, Retriever, SearchHit,
-    SearchMode, SearchOpts, SearchQuery, VectorStore,
+    Answer, DocumentStore, Embedder, ExtractContext, Extractor, IndexVersion, LanguageModel,
+    MediaType, Retriever, SearchHit, SearchMode, SearchOpts, SearchQuery, VectorStore,
 };
 use kebab_embed_local::FastembedEmbedder;
 use kebab_llm_local::OllamaLanguageModel;
+use kebab_parse_code::{
+    CAstExtractor, CppAstExtractor, GoAstExtractor, JavaAstExtractor,
+    JavascriptAstExtractor, KotlinAstExtractor, PythonAstExtractor, RustAstExtractor,
+    TypescriptAstExtractor,
+};
+use kebab_parse_image::ImageExtractor;
+use kebab_parse_pdf::PdfTextExtractor;
 use kebab_rag::{AskOpts, RagPipeline};
 use kebab_search::{HybridRetriever, LexicalRetriever, VectorRetriever};
 use kebab_store_sqlite::SqliteStore;
@@ -115,6 +122,12 @@ pub fn short_query_hint(query_text: &str, hits_empty: bool) -> Option<String> {
 pub struct App {
     pub(crate) config: kebab_config::Config,
     pub(crate) sqlite: Arc<SqliteStore>,
+    /// post-v0.18.0 extractor-dispatch-unification: polymorphic Extractor
+    /// registry. App init 시 1회 등록되어 `extract_for(...)` 가 lookup
+    /// 한다. 현재 11 entry (ImageExtractor + PdfTextExtractor + 9 AST).
+    /// MarkdownExtractor 는 별 PR 에서 추가 — markdown ingest path 는
+    /// 본 PR 에서 free-function 그대로 유지.
+    pub(crate) extractors: Vec<Box<dyn Extractor + Send + Sync>>,
     /// Memoized embedder — built lazily on first `embedder()` call when
     /// embeddings are enabled. `OnceLock` keeps the struct `Sync` and
     /// the build path cold-only-once.
@@ -204,6 +217,25 @@ impl App {
         // `None` (cache disabled — every search hits the retrievers).
         let search_cache = NonZeroUsize::new(config.search.cache_capacity)
             .map(|cap| Mutex::new(LruCache::new(cap)));
+        // post-v0.18.0 extractor-dispatch-unification: build the 11-entry
+        // Extractor registry. All entries are state-less unit structs with
+        // zero-cost `new()`, so init cost is effectively 0 and side effects
+        // are 0 — `pipeline_verifier` fallible `?` below may bail but the
+        // already-constructed `extractors` Vec drops without cost. Markdown
+        // is NOT registered (see field doc).
+        let extractors: Vec<Box<dyn Extractor + Send + Sync>> = vec![
+            Box::new(ImageExtractor::new()),
+            Box::new(PdfTextExtractor::new()),
+            Box::new(RustAstExtractor::new()),
+            Box::new(PythonAstExtractor::new()),
+            Box::new(TypescriptAstExtractor::new()),
+            Box::new(JavascriptAstExtractor::new()),
+            Box::new(GoAstExtractor::new()),
+            Box::new(JavaAstExtractor::new()),
+            Box::new(KotlinAstExtractor::new()),
+            Box::new(CAstExtractor::new()),
+            Box::new(CppAstExtractor::new()),
+        ];
         // p9-fb-41 PR-9c-2: build the NLI verifier when the gate is
         // enabled. App carries it on `RagPipeline` via
         // `with_verifier` so the rag crate doesn't have to know about
@@ -222,6 +254,7 @@ impl App {
         Ok(Self {
             config,
             sqlite: Arc::new(sqlite),
+            extractors,
             embedder: OnceLock::new(),
             vector: OnceLock::new(),
             llm: OnceLock::new(),
@@ -230,6 +263,30 @@ impl App {
         })
     }
 
+    /// Polymorphic dispatcher for the [`Extractor`] trait. Looks up the
+    /// first Extractor whose `supports(media)` returns true and invokes
+    /// `extract(ctx, bytes)` on it.
+    ///
+    /// Errors with `anyhow!("no Extractor for media_type {media:?}")`
+    /// when no matching Extractor is registered. Callers in
+    /// `ingest_one_*_asset` reach this only after the outer 4-arm
+    /// dispatch (`MediaType::Markdown` / `Image` / `Pdf` / `Code(lang)`)
+    /// has matched, so a miss is a programming error — NOT a user-
+    /// facing skip.
+    pub(crate) fn extract_for(
+        &self,
+        media: &MediaType,
+        ctx: &ExtractContext<'_>,
+        bytes: &[u8],
+    ) -> Result<kebab_core::CanonicalDocument> {
+        let extractor = self
+            .extractors
+            .iter()
+            .find(|e| e.supports(media))
+            .ok_or_else(|| anyhow!("no Extractor for media_type {media:?}"))?;
+        extractor.extract(ctx, bytes)
+    }
+
     /// Run a [`SearchQuery`] through the configured retriever stack and
     /// return the top-k hits. p9-fb-19: result is served from the
     /// in-process LRU cache when the same `(query_norm, mode, k,
@@ -1157,3 +1214,128 @@ mod tests_trace {
         assert!(resp.trace.is_some(), "trace populated when opts.trace=true");
     }
 }
+
+/// post-v0.18.0 extractor-dispatch-unification: in-crate unit tests for
+/// the `App.extractors` registry + `App::extract_for` polymorphic
+/// dispatch. In-crate (not `tests/`) because `extractors` + `extract_for`
+/// are `pub(crate)` — integration tests cannot reach them.
+///
+/// Spec §5.1 + plan §2 Step 10 — 3 test class:
+/// 1. registry length = 11 (image + pdf + 9 AST).
+/// 2. mutually-exclusive `supports()` grid over 16 sample MediaTypes.
+/// 3. `extract_for` returns `Err("no Extractor ...")` for registry-NOT-cover
+///    MediaType (Audio).
+#[cfg(test)]
+mod tests_extractor_dispatch {
+    use super::*;
+    use kebab_core::{AudioType, ExtractConfig, ImageType};
+
+    /// helper: tempdir-isolated App for tests (mirrors `tests_trace`'s
+    /// `open_app_with_temp_dir` pattern).
+    fn open_app_with_temp_dir() -> (tempfile::TempDir, App) {
+        let dir = tempfile::tempdir().unwrap();
+        let mut cfg = kebab_config::Config::defaults();
+        cfg.storage.data_dir = dir.path().to_string_lossy().into_owned();
+        // Bring up migrations.
+        let store = kebab_store_sqlite::SqliteStore::open(&cfg).unwrap();
+        store.run_migrations().unwrap();
+        drop(store);
+        let app = App::open_with_config(cfg).unwrap();
+        (dir, app)
+    }
+
+    /// Registry length invariant: 11 Extractor (image + pdf + 9 AST).
+    /// Markdown is NOT registered (free-function path — defer to a
+    /// separate PR per spec §3.4).
+    #[test]
+    fn registry_has_eleven_extractors() {
+        let (_dir, app) = open_app_with_temp_dir();
+        assert_eq!(
+            app.extractors.len(),
+            11,
+            "registry must hold 11 Extractors (image + pdf + 9 AST). \
+             markdown 은 별 PR."
+        );
+    }
+
+    /// 11 Extractor 의 `supports()` 가 16 sample MediaType 에 대해
+    /// mutually exclusive — 어떤 두 Extractor 도 동일 MediaType 에
+    /// 대해 true 반환 안 됨.
+    #[test]
+    fn supports_grid_is_mutually_exclusive() {
+        let (_dir, app) = open_app_with_temp_dir();
+        let samples = vec![
+            MediaType::Markdown,
+            MediaType::Pdf,
+            MediaType::Image(ImageType::Png),
+            MediaType::Image(ImageType::Jpeg),
+            MediaType::Code("rust".into()),
+            MediaType::Code("python".into()),
+            MediaType::Code("typescript".into()),
+            MediaType::Code("javascript".into()),
+            MediaType::Code("go".into()),
+            MediaType::Code("java".into()),
+            MediaType::Code("kotlin".into()),
+            MediaType::Code("c".into()),
+            MediaType::Code("cpp".into()),
+            MediaType::Code("yaml".into()),  // registry NOT cover
+            MediaType::Code("shell".into()), // registry NOT cover
+            MediaType::Audio(AudioType::Wav), // registry NOT cover
+        ];
+        for sample in &samples {
+            let hits: Vec<_> = app
+                .extractors
+                .iter()
+                .filter(|e| e.supports(sample))
+                .collect();
+            assert!(
+                hits.len() <= 1,
+                "mutually exclusive violated for {sample:?}: {} hits",
+                hits.len()
+            );
+        }
+    }
+
+    /// `extract_for` 가 registry NOT cover MediaType (Audio) 에 대해
+    /// `Err("no Extractor for media_type ...")` 반환. Audio MediaType
+    /// 사용으로 RawAsset 의 actual content 의존 회피 — registry NOT
+    /// cover → 즉시 Err.
+    #[test]
+    fn extract_for_unsupported_media_errors() {
+        let (_dir, app) = open_app_with_temp_dir();
+
+        // Minimal RawAsset. Actual content never read — Audio MediaType
+        // 는 registry NOT cover → `extract_for` 가 dispatch loop 안에서
+        // 바로 Err 반환. RawAsset field set 은 `crates/kebab-core/src/
+        // asset.rs:62-73` 와 정합 (8 field).
+        let asset = kebab_core::RawAsset {
+            asset_id: kebab_core::AssetId("00".repeat(16)),
+            source_uri: kebab_core::SourceUri::File("/tmp/dummy.wav".into()),
+            workspace_path: kebab_core::WorkspacePath("dummy.wav".to_string()),
+            media_type: MediaType::Audio(AudioType::Wav),
+            byte_len: 0,
+            checksum: kebab_core::Checksum("00".repeat(32)),
+            discovered_at: time::OffsetDateTime::now_utc(),
+            // AssetStorage::Inline 미존재 — actual variant `Copied { path }`
+            // 사용 (kebab-core/src/asset.rs:55-60).
+            stored: kebab_core::AssetStorage::Copied {
+                path: std::path::PathBuf::from("/tmp/dummy.wav"),
+            },
+        };
+
+        let workspace_root: std::path::PathBuf = std::path::PathBuf::from("/tmp");
+        let cfg = ExtractConfig::default();
+        let ctx = ExtractContext {
+            asset: &asset,
+            workspace_root: &workspace_root,
+            config: &cfg,
+        };
+        let result = app.extract_for(&MediaType::Audio(AudioType::Wav), &ctx, &[]);
+        assert!(result.is_err(), "Audio 는 registry 미포함 → Err 기대");
+        let err_msg = format!("{:#}", result.unwrap_err());
+        assert!(
+            err_msg.contains("no Extractor"),
+            "unexpected err: {err_msg}"
+        );
+    }
+}

crates/kebab-app/src/lib.rs

@@ -43,14 +43,12 @@ use kebab_chunk::{CodeCAstV1Chunker, CodeCppAstV1Chunker, CodeGoAstV1Chunker, Co
 use kebab_core::{
     Answer, Block, CanonicalDocument, Chunk, ChunkId, ChunkPolicy, ChunkerVersion, Chunker,
     DocFilter, DocSummary, DocumentId, DocumentStore, Embedder, EmbeddingInput,
-    EmbeddingKind, ExtractContext, Extractor, IngestReport, Lang, LanguageModel, MediaType,
+    EmbeddingKind, ExtractContext, IngestReport, Lang, LanguageModel, MediaType,
     ParserVersion, RawAsset, SearchHit, SearchQuery, SourceScope,
     SourceUri, VectorRecord, VectorStore,
 };
 use kebab_llm_local::OllamaLanguageModel;
-use kebab_parse_image::{ImageExtractor, OllamaVisionOcr, apply_caption, apply_ocr};
-use kebab_parse_code::{CAstExtractor, CppAstExtractor, GoAstExtractor, JavaAstExtractor, JavascriptAstExtractor, KotlinAstExtractor, PythonAstExtractor, RustAstExtractor, TypescriptAstExtractor};
-use kebab_parse_pdf::PdfTextExtractor;
+use kebab_parse_image::{OllamaVisionOcr, apply_caption, apply_ocr};
 use kebab_parse_md::{BodyHints, build_canonical_document, parse_blocks, parse_frontmatter};
 use kebab_source_fs::FsSourceConnector;
 
@@ -353,9 +351,7 @@ pub fn ingest_with_config_opts(
     } else {
         None
     };
-    let image_extractor = ImageExtractor::new();
     let image_pipeline = ImagePipeline {
-        extractor: &image_extractor,
         ocr_engine: ocr_engine.as_ref(),
         caption_llm: caption_llm.as_deref(),
     };
@@ -758,7 +754,6 @@ type SqliteStoreAlias = kebab_store_sqlite::SqliteStore;
 /// once per ingest invocation. Threaded through `ingest_one_asset` so
 /// the dispatch does not need ten separate parameters.
 struct ImagePipeline<'a> {
-    extractor: &'a ImageExtractor,
     ocr_engine: Option<&'a OllamaVisionOcr>,
     caption_llm: Option<&'a dyn LanguageModel>,
 }
@@ -1232,7 +1227,6 @@ fn ingest_one_image_asset(
     image_pipeline: &ImagePipeline<'_>,
     force_reingest: bool,
 ) -> anyhow::Result<kebab_core::IngestItem> {
-    let image_extractor = image_pipeline.extractor;
     let ocr_engine = image_pipeline.ocr_engine;
     let caption_llm = image_pipeline.caption_llm;
     let path = match &asset.source_uri {
@@ -1291,9 +1285,9 @@ fn ingest_one_image_asset(
         workspace_root: &workspace_root,
         config: &extract_config,
     };
-    let mut canonical = image_extractor
-        .extract(&ctx, &bytes)
-        .context("kb-parse-image::ImageExtractor::extract")?;
+    let mut canonical = app
+        .extract_for(&asset.media_type, &ctx, &bytes)
+        .context("kb-app::extract_for (image)")?;
 
     // 2 + 3. Apply OCR / caption when their adapters exist. Both are
     //        Lenient — failure is captured into Provenance Warning,
@@ -1780,9 +1774,9 @@ fn ingest_one_pdf_asset(
         workspace_root: &workspace_root,
         config: &extract_config,
     };
-    let mut canonical = PdfTextExtractor::new()
-        .extract(&ctx, &bytes)
-        .context("kb-parse-pdf::PdfTextExtractor::extract")?;
+    let mut canonical = app
+        .extract_for(&asset.media_type, &ctx, &bytes)
+        .context("kb-app::extract_for (pdf)")?;
 
     // Per-medium chunker selection: PDF docs always use pdf-page-v1
     // regardless of `config.chunking.chunker_version`. The chunker
@@ -2007,43 +2001,24 @@ fn ingest_one_code_asset(
         config: &extract_config,
     };
 
-    // p10-1b Task D/G/J/L: extractor per-lang.
+    // post-v0.18.0 extractor-dispatch-unification:
+    // 9 AST lang 의 dispatch 가 polymorphic — App.extractors registry 의
+    // `*AstExtractor` entry 가 lang string 으로 disjoint `supports()` 비교
+    // 후 단일 hit. Tier 2 (manifest) + Tier 3 (shell) 은 free-function
+    // `synthesize_tier2_document` 유지 (Extractor impl 아님 — 별 PR).
     // p10-3: capture Result so Tier 1 extractor errors can fall back to Tier 3.
     let canonical_result: anyhow::Result<kebab_core::CanonicalDocument> = match code_lang {
-        "rust" => RustAstExtractor::new()
-            .extract(&ctx, &bytes)
-            .context("kb-parse-code::RustAstExtractor::extract (code:rust)"),
-        "python" => PythonAstExtractor::new()
-            .extract(&ctx, &bytes)
-            .context("kb-parse-code::PythonAstExtractor::extract (code:python)"),
-        "typescript" => TypescriptAstExtractor::new()
-            .extract(&ctx, &bytes)
-            .context("kb-parse-code::TypescriptAstExtractor::extract (code:typescript)"),
-        "javascript" => JavascriptAstExtractor::new()
-            .extract(&ctx, &bytes)
-            .context("kb-parse-code::JavascriptAstExtractor::extract (code:javascript)"),
-        "go" => GoAstExtractor::new()
-            .extract(&ctx, &bytes)
-            .context("kb-parse-code::GoAstExtractor::extract (code:go)"),
-        "java" => JavaAstExtractor::new()
-            .extract(&ctx, &bytes)
-            .context("kb-parse-code::JavaAstExtractor::extract (code:java)"),
-        "kotlin" => KotlinAstExtractor::new()
-            .extract(&ctx, &bytes)
-            .context("kb-parse-code::KotlinAstExtractor::extract (code:kotlin)"),
+        // 9 AST lang: rust / python / typescript / javascript / go / java / kotlin / c / cpp
+        "rust" | "python" | "typescript" | "javascript" | "go" | "java" | "kotlin" | "c"
+        | "cpp" => app
+            .extract_for(&asset.media_type, &ctx, &bytes)
+            .with_context(|| format!("kb-app::extract_for (code:{code_lang})")),
         // p10-2 Tier 2: no extractor — synthesize Document directly from raw bytes.
         "yaml" | "dockerfile" | "toml" | "json" | "xml" | "groovy" | "go-mod" => {
             synthesize_tier2_document(asset, &bytes, code_lang, &parser_version)
         }
         // p10-3: shell reuses the same synthesizer.
         "shell" => synthesize_tier2_document(asset, &bytes, "shell", &parser_version),
-        // p10-1D: C + C++ AST extractors.
-        "c" => CAstExtractor::new()
-            .extract(&ctx, &bytes)
-            .context("kebab-parse-code::CAstExtractor::extract (code:c)"),
-        "cpp" => CppAstExtractor::new()
-            .extract(&ctx, &bytes)
-            .context("kebab-parse-code::CppAstExtractor::extract (code:cpp)"),
         other => anyhow::bail!("unreachable (extract): {other}"),
     };