docs(tasks): P6-4 image ingest wiring task spec

P6-1 / P6-2 / P6-3 의 라이브러리 파이프라인 (`ImageExtractor`, `OllamaVisionOcr`, `apply_caption`) 이 모두 머지되어 있지만 `kebab-app::ingest_with_config` 의 dispatch 가 markdown 만 처리하므로 CLI 에서 이미지 자산이 색인되지 않는 미완 구간 존재. 본 spec 은 그 wiring 을 별도 component task 로 잡아 P6-1/2/3 의 frozen contract 는 보존하고 통합만 본 task 의 contract 로 진행되게 한다. 핵심 결정 (사용자 brainstorming 반영): - 청킹 옵션 A — `kebab-chunk::md_heading_v1` 에 image-only document 분기 추가, 단일 합성 청크 emit. - 청크 텍스트 포맷 (β) — `<alt>\n\n<ocr.joined>\n\n<caption.text>` plain concatenation. 라벨 없음. 빈 부분 drop. - 실패 정책 (b) Lenient — extract 성공이면 doc 저장, OCR/caption 부분 실패는 Provenance Warning + `errors` 카운터 미증가. - LM 인스턴스 — ingest 세션당 1회 빌드, `&dyn LanguageModel` 공유. - 책 / 스캔 PDF — P6-4 scope 외, P7 PDF 라인이 책임. - P6-5 (image-scale-hardening) 미시작 — 사용자 시나리오가 \"다이어그램 / 스크린샷 / 카메라 사진\" 으로 좁아져 불필요. INDEX.md: P6 \"3 components\" → \"4 components\". contract: docs/superpowers/specs/2026-04-27-kebab-final-form-design.md sections: §3.4 ImageRefBlock, §6.1 ingest pipeline, §7.2 Extractor/Chunker traits, §9.1 image extraction policy.
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+---
+phase: P6
+component: kebab-app (image ingest dispatch + chunking)
+task_id: p6-4
+title: "Wire ImageExtractor + OCR + caption into kebab-app::ingest end-to-end"
+status: planned
+depends_on: [p6-1, p6-2, p6-3, p1-6, p3-5]
+unblocks: []
+contract_source: ../../docs/superpowers/specs/2026-04-27-kebab-final-form-design.md
+contract_sections: [§3.4 ImageRefBlock, §6.1 ingest pipeline, §7.2 Extractor/Chunker traits, §9.1 image extraction policy]
+---
+
+# p6-4 — Image ingest wiring (kebab-app + chunker)
+
+## Goal
+
+Make `kebab ingest` end-to-end functional for image assets. The library-level pipeline (`ImageExtractor`, `OllamaVisionOcr`, `apply_caption`) is complete and tested in isolation — this task connects the wires from `kebab-source-fs` (which already classifies `.png` / `.jpg` / `.webp` / `.gif` / `.tiff` as `MediaType::Image(_)`) through `kebab-app::ingest_with_config` to `kebab-store-sqlite` + `kebab-store-vector`, so a user running `kebab ingest` against a workspace containing diagrams / screenshots / camera photos sees those assets indexed and searchable.
+
+## Why now / why this size
+
+P6-1 / P6-2 / P6-3 each shipped a focused library and a passing test suite, but all three deliver value only after `kebab-app::ingest` learns how to dispatch on `MediaType::Image(_)`. The wiring is small (one new dispatch arm, one chunking branch, one LM-construction call site) but materially user-facing — without it, the entire P6 phase is invisible from the CLI. Pulling this into its own task keeps the P6-1/2/3 specs frozen as written while letting the integration evolve under its own contract.
+
+## Allowed dependencies
+
+- `kebab-core`
+- `kebab-config`
+- `kebab-source-fs`
+- `kebab-parse-image` (consumes its public surface)
+- `kebab-llm-local` (constructs `OllamaLanguageModel` for caption)
+- `kebab-chunk` (image-document branch in `md-heading-v1`)
+- `kebab-store-sqlite`, `kebab-store-vector`, `kebab-embed-local`
+- `anyhow`, `serde_json`, `tracing`
+
+## Forbidden dependencies
+
+- New crates outside the existing `kebab-app` dep set. Any image-specific logic that doesn't fit `kebab-app` belongs in `kebab-parse-image` (already shipped) or `kebab-chunk` (this task may extend it).
+
+## Inputs
+
+| input | type | source |
+|-------|------|--------|
+| workspace assets | `RawAsset` stream | `kebab-source-fs::SourceConnector::scan` (already classifies image types) |
+| image bytes | `&[u8]` | filesystem read in `kebab-app` |
+| `Config` | `kebab_config::Config` | CLI `--config` flag → `Config::load` |
+| OCR config | `config.image.ocr` | P6-2 |
+| Caption config | `config.image.caption` | P6-3 |
+
+## Outputs
+
+| output | type | downstream |
+|--------|------|------------|
+| `CanonicalDocument` per image | written via `DocumentStore::put_document` | `kebab-store-sqlite` |
+| One synthesized chunk per image | `Vec<Chunk>` (length 1) | `kebab-store-sqlite::put_chunks` + `kebab-store-vector::upsert` |
+| Updated `IngestReport` counters | `scanned / new / updated / skipped / errors` | wire output (`ingest_report.v1`) |
+
+## Public surface
+
+No new public types. The wiring exists inside `kebab-app::ingest_with_config` (and its private helpers). `kebab-chunk` gains one image-only branch in `md_heading_v1`:
+
+```rust
+// crates/kebab-chunk/src/md_heading_v1.rs (additions only — sketch)
+fn chunk(&self, doc: &CanonicalDocument, policy: &ChunkPolicy) -> Result<Vec<Chunk>> {
+    if is_image_only_document(doc) {
+        return Ok(vec![image_chunk(doc, policy)?]);
+    }
+    // ... existing markdown heading logic untouched ...
+}
+
+fn is_image_only_document(doc: &CanonicalDocument) -> bool {
+    doc.blocks.len() == 1
+        && matches!(doc.blocks.first(), Some(Block::ImageRef(_)))
+}
+
+fn image_chunk(doc: &CanonicalDocument, policy: &ChunkPolicy) -> Result<Chunk> {
+    let block = match &doc.blocks[0] {
+        Block::ImageRef(b) => b,
+        _ => unreachable!("guarded by is_image_only_document"),
+    };
+    let text = compose_image_chunk_text(block);
+    // chunk_id derived from doc_id + chunker_version + [block_id] + policy_hash
+    // (existing §4.2 recipe — no new ID kind).
+    Ok(Chunk { /* ... */ })
+}
+```
+
+`compose_image_chunk_text` is the canonical place where the (β) plain-concatenation policy lives:
+
+```rust
+fn compose_image_chunk_text(block: &ImageRefBlock) -> String {
+    let alt = if block.alt.is_empty() {
+        // alt should never be empty at this stage because P6-1 falls
+        // back to the filename when it is, but the chunker stays
+        // defensive — an empty first line would degrade lexical
+        // search hits on filenames.
+        block.src.rsplit('/').next().unwrap_or("[image]").to_string()
+    } else {
+        block.alt.clone()
+    };
+    let ocr = block.ocr.as_ref().map(|o| o.joined.as_str()).unwrap_or("");
+    let cap = block.caption.as_ref().map(|c| c.text.as_str()).unwrap_or("");
+    [alt, ocr.to_string(), cap.to_string()]
+        .into_iter()
+        .filter(|s| !s.is_empty())
+        .collect::<Vec<_>>()
+        .join("\n\n")
+}
+```
+
+## Behavior contract
+
+### ingest dispatch (kebab-app)
+
+- `kebab-app::ingest_with_config` reads the asset stream from `kebab-source-fs`. For each `RawAsset`:
+  - `MediaType::Markdown` → existing markdown extractor path (unchanged).
+  - `MediaType::Image(_)` → new image branch (this task).
+  - `MediaType::Pdf | MediaType::Audio(_) | MediaType::Other(_)` → `skipped += 1` (existing behaviour).
+- Image branch:
+  1. Read bytes via `kebab-source-fs` (existing helper).
+  2. Build a `kebab_core::ExtractContext { asset, workspace_root, config: &ExtractConfig::default() }`.
+  3. Call `ImageExtractor::new().extract(&ctx, &bytes)`. Failure (`Err(_)`) → `errors += 1`, log, continue to next asset (do not abort the whole ingest).
+  4. Take a mutable borrow of `doc.blocks[0]` (must be `Block::ImageRef`); take a mutable borrow of `doc.provenance.events`.
+  5. If `config.image.ocr.enabled`:
+     - Build `OllamaVisionOcr::new(&cfg)`.
+     - Call `apply_ocr(&engine, &bytes, block, lang_hint, &mut events)`.
+     - Failure → log a `tracing::warn!`, append `ProvenanceKind::Warning` event with the error message via the helper, continue.
+     - `block.ocr` stays `None` on failure (P6-2 contract).
+  6. If `config.image.caption.enabled`:
+     - Build the LM **once per ingest session** (not per asset) — see "LM construction" below.
+     - Call `apply_caption(&*llm, &bytes, block, lang_hint, &cfg, &mut events)`.
+     - Failure → same lenient policy as OCR: warn, log, continue. `block.caption` stays `None`.
+  7. Pass the (possibly partially-populated) `CanonicalDocument` to the existing chunker → embedder → store path, identical to markdown.
+
+### Lang hint
+
+- `lang_hint: Option<&Lang>` passed to `apply_ocr` / `apply_caption` reads from `doc.lang` (set to `Lang("und")` by P6-1).
+- `kebab-parse-image` already special-cases `"und"` so the prompt does not embed a misleading hint.
+
+### LM construction
+
+- The caption path constructs `OllamaLanguageModel::new(&cfg)` **once per ingest invocation**, before the asset loop, when `config.image.caption.enabled = true`. Stored as a stack-allocated `Box<dyn LanguageModel>` (or trait object behind `&`) and passed to `apply_caption`.
+- Construction failure (e.g. invalid endpoint string) → ingest aborts with the constructor's error before scanning. Never silently disables caption.
+- `reqwest::blocking::Client` inside `OllamaLanguageModel` is internally `Arc`-shared, so reusing one instance across hundreds of asset iterations is correct and cheap.
+
+### Chunking (kebab-chunk md-heading-v1)
+
+- The chunker gains an image-only branch as sketched above. The branch:
+  - Returns exactly one `Chunk` per image document.
+  - `chunk.text` = (β) plain concatenation of `[alt, ocr_joined, caption_text]` joined by `\n\n`, dropping empty parts.
+  - `chunk.block_ids = vec![block.common.block_id.clone()]`.
+  - `chunk.heading_path = vec![]` (image documents have no heading hierarchy).
+  - `chunk.section_label = None`.
+  - `chunk.source_span = block.common.source_span.clone()` (the `Region { x, y, w, h }` from P6-1).
+- Determinism: the existing `id_for_chunk(doc_id, chunker_version, &[block_id], policy_hash)` recipe applies unchanged.
+- Oversized text: an image whose `ocr.joined` exceeds `policy.target_tokens` produces an oversized chunk. Acceptable in v1 — the user-facing scenario (diagrams / screenshots / camera photos) typically yields ≤ 1 page of OCR. Books are routed through P7 PDF instead (see "Out of scope"). A `tracing::warn!` fires when this happens so a future P+ task can quantify how often the boundary is hit.
+
+### `enabled = false` for both
+
+- When `config.image.ocr.enabled = false` AND `config.image.caption.enabled = false`, the image is still extracted, stored, and chunked — the user gets EXIF + dimensions + filename indexed, with empty OCR / caption.
+- The synthesized chunk text falls back to just the filename. Lexical search on filenames still works; vector search produces a best-effort embedding from a one-line input.
+
+### Failure semantics summary
+
+| failure | counter | doc stored? | provenance |
+|---|---|---|---|
+| `ImageExtractor::extract` Err (decode fail / unrecognised) | `errors+=1` | no | n/a |
+| `MediaType::Image(_)` but `supports()` returns false (won't happen with current trait — defensive) | `skipped+=1` | no | n/a |
+| `apply_ocr` Err | unchanged | yes (block.ocr = None) | `ProvenanceKind::Warning`, agent `kb-app` |
+| `apply_caption` Err | unchanged | yes (block.caption = None) | `ProvenanceKind::Warning`, agent `kb-app` |
+| HEIC / RAW → `MediaType::Other(_)` | `skipped+=1` (existing) | no | n/a |
+
+## Storage / wire effects
+
+- `kebab-store-sqlite::documents` table gains rows whose `parser_version = "image-meta-v1"`.
+- `kebab-store-sqlite::blocks` table gains rows of `block_kind = "imageref"`.
+- `kebab-store-sqlite::chunks` table gains rows whose `chunker_version = "md-heading-v1"` AND whose `block_ids` reference a single `imageref` block.
+- `kebab-store-vector::chunk_embeddings_<model>_<dim>` gains one vector per image chunk.
+- `IngestReport` (wire `ingest_report.v1`) counters update naturally: `scanned` includes images, `new` / `updated` track image docs, `errors` counts decode failures, `skipped` counts unsupported formats.
+- No new wire schemas or `kebab-core` types.
+
+## Test plan
+
+| kind | description | fixture / data |
+|------|-------------|----------------|
+| integration | TempDir KB + 1 PNG (`hello-world.png` with text) + `image.ocr.enabled = true` + `image.caption.enabled = false` (mock LM unused) → `kebab-app::ingest` produces 1 doc + 1 chunk; chunk text contains the filename + OCR text | `kebab-app/tests/image_pipeline.rs` (new), wiremock for OCR Ollama call |
+| integration | Same fixture but `caption.enabled = true` with mock LM returning `"a red square with text"` → chunk text contains alt + OCR + caption joined by `\n\n` | wiremock for Ollama (both `/api/generate` calls) |
+| integration | Determinism: ingest the same PNG twice → identical `doc_id`, `chunk_id` (P1 idempotency contract holds) | inline |
+| integration | OCR Ollama returns 503 → asset still indexed; `block.ocr = None`; provenance has Warning event; `errors` counter NOT incremented; ingest returns Ok | wiremock |
+| integration | Caption Ollama returns 503 → asset still indexed; `block.caption = None`; provenance Warning; `errors` not incremented | wiremock |
+| integration | `image.ocr.enabled = false` AND `image.caption.enabled = false` → image still indexed; chunk text = filename only | inline |
+| integration | Hybrid search across mixed corpus (1 markdown + 1 PNG) returns image chunk for an OCR-text query | inline (real `multilingual-e5-small` embedding) |
+| integration | `kebab inspect doc <image_doc_id>` returns the image `CanonicalDocument` with `block.ocr` / `block.caption` populated | inline |
+| unit | `kebab-chunk::md_heading_v1::is_image_only_document` returns true for `[ImageRef]`, false for `[Heading, ImageRef]` (image embedded in markdown — currently a P+ case but the predicate must not misfire) | unit |
+| unit | `compose_image_chunk_text` drops empty parts: alt-only, alt+ocr, alt+caption, alt+ocr+caption all formatted correctly | unit |
+| smoke | Update `docs/SMOKE.md` so the runbook ingests at least one image fixture and verifies search-by-OCR-text works | docs change |
+
+The opt-in real-Ollama integration test from P6-2 / P6-3 stays inside `kebab-parse-image`; this task's integration tests use wiremock so `cargo test --workspace` stays hermetic.
+
+## Definition of Done
+
+- [ ] `cargo check --workspace` passes
+- [ ] `cargo test --workspace --no-fail-fast -j 1` passes (all new integration tests green)
+- [ ] `cargo clippy --workspace --all-targets -- -D warnings` passes
+- [ ] `kebab ingest` against a TempDir KB containing 1 markdown + 1 PNG produces `scanned 2 / new 2 / errors 0`
+- [ ] `kebab search --mode lexical "<OCR text>"` returns the image chunk
+- [ ] `kebab inspect doc <image_doc_id>` shows non-empty `block.ocr` / `block.caption`
+- [ ] `docs/SMOKE.md` includes an image-fixture step
+- [ ] PR links design §3.4, §6.1, §9.1
+- [ ] `tasks/INDEX.md` updated to "P6 — 4 components"
+
+## Out of scope
+
+- **Books / scanned PDFs** — routed through P7 PDF pipeline. P7's PDF text extractor handles text-embed PDFs natively; scanned PDFs are P7's internal concern (page render → OCR call to the same `kebab-parse-image::OllamaVisionOcr` adapter).
+- **Image-region chunker** — current `OllamaVisionOcr` returns a single full-image region, so per-region chunking has no signal. When a region-aware engine (Tesseract / Apple Vision sidecar) lands, a separate `image-region-chunker` task can split on `OcrText.regions[]`.
+- **Long-OCR splitting** — image documents whose OCR exceeds `target_tokens` produce oversized chunks. Acceptable for diagrams / screenshots / photos (the v1 user scenario per the brainstorming with the user). Books deliberately use the PDF path instead.
+- **Retry mechanism for partial OCR / caption failures** — current escape hatch is "delete the asset, re-ingest". A `kebab ingest --retry-image-analysis` flag is a P+ enhancement once operational data shows it's needed.
+- **Parallelism beyond `config.indexing.max_parallel_extractors`** — the existing knob applies. Per-image OCR-bound parallelism (multiple in-flight Ollama calls) is a P+ scale-hardening task that has been explicitly de-scoped because the user routes books through PDF instead of image.
+- **Progress reporting** (`kebab ingest --progress`) — same reasoning as parallelism.
+- **W3C Media Fragments citation form** (`path#xywh=...`) — `Citation` already carries `Region` source span; fragment URI rendering can be a wire-only follow-up when downstream UI needs it.
+- **Wire schema bump** — no new wire types; `ingest_report.v1` counters absorb image events naturally.
+
+## Risks / notes
+
+- **OCR / caption failures are silent in `IngestReport` counters.** The user only sees them via `--debug` traces or `kebab inspect doc <id>` (Provenance Warning events). This is the intentional Lenient policy from the brainstorming; flag in the PR description so users know how to detect partial failures. A future spec extension could introduce a `image_ocr_failed` / `image_caption_failed` counter alongside `errors`.
+- **LM endpoint validation runs once per ingest.** A misconfigured `models.llm.endpoint` aborts ingest before any asset is processed. This is correct fail-fast behaviour but means a single broken endpoint takes the whole ingest down — even markdown assets that don't need the LM. The user fix is `image.caption.enabled = false` or correcting the endpoint.
+- **`unreachable!` in the chunker branch is guarded by `is_image_only_document`.** If a future task introduces multi-block image documents (e.g. embedded markdown caption alongside the image), the predicate must change in lockstep. Keep both functions in the same module so the invariant is local.
+- **Determinism stress.** The existing markdown path's `kb-normalize::build_canonical_document` shares one `now_utc()` reading across the per-document Provenance events. The image path needs the same: P6-1 already does `let now = OffsetDateTime::now_utc();` once and reuses it for both events; this task's wiring must not introduce a second `now()` call between extract and apply_ocr/caption that would break per-document timestamp parity.