diff --git a/CLAUDE.md b/CLAUDE.md
index 6ed5f32..4dbd472 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -94,6 +94,7 @@ Release 절차:
 - XDG paths: `~/.config/kebab/`, `~/.local/share/kebab/`, `~/.cache/kebab/`, `~/.local/state/kebab/`.
 - SQLite filename: `kebab.sqlite` (under `data_dir`).
 - Workspace ignore: `.kebabignore` (per directory).
+- `_external/` (under `workspace.root`): single-file / stdin ingest 가 외부 file 을 deterministic 명명 (`<blake3-12>.<ext>`) 으로 copy. 첫 생성 시 `.kebabignore` 자동 append.
 
 The migration from the old `kb` name lives in commits `911fb49 / f1a448d / f9714aa`. If you spot a leftover `kb` reference, treat it as a leftover and fix it (the rename PR sweep covered crates/, docs/, tasks/, README, design doc, fixtures — but workspace root `Cargo.toml` comments needed a follow-up; assume similar misses are possible).
 
diff --git a/HANDOFF.md b/HANDOFF.md
index bd6c164..b32ed74 100644
--- a/HANDOFF.md
+++ b/HANDOFF.md
@@ -31,6 +31,7 @@ P0~P5 직렬. P6~P9 P5 이후 병렬 가능.
 
 머지 후 발견된 모든 deviation / hotfix 의 dated 로그는 [tasks/HOTFIXES.md](tasks/HOTFIXES.md). 본 요약은 \"누군가가 인수받을 때 알아두면 시간을 많이 절약하는\" 항목만:
 
+- **2026-05-07 P9 post-도그푸딩 (p9-fb-31)** — `kebab ingest-file <path>` + `kebab ingest-stdin --title <T>` 두 신규 subcommand + MCP tool `ingest_file` / `ingest_stdin` (4 → 6 tool). agent 가 fetch 한 web markdown / 외부 file 을 KB 에 즉시 저장. workspace 외부 file 은 `<workspace.root>/_external/<blake3-12>.<ext>` 로 copy (deterministic 명명 → idempotent). `_external/` 디렉토리 첫 생성 시 `.kebabignore` 자동 append (walk 무한 루프 방지). stdin 은 markdown 전용 + flag (`--title`, `--source-uri`) → frontmatter 자동 prepend. .kebabignore 매치 시 stderr warn 후 진행 (explicit ingest = bypass intent). fb-30 의 v1 read-only MCP 정책 변경 — 첫 mutation tool 도입. spec: `tasks/p9/p9-fb-31-single-file-stdin-ingest.md`. design: `docs/superpowers/specs/2026-05-07-p9-fb-31-single-file-stdin-ingest-design.md`.
 - **2026-05-07 P9 post-도그푸딩 (p9-fb-30)** — `kebab mcp` 신규 subcommand + new crate `kebab-mcp` (lib only) — stdio JSON-RPC server. 4 read-only tool (`search` / `ask` / `schema` / `doctor`) 가 `kebab-app` facade 위에 build. rmcp 1.6 SDK 채택, manual `tools/list` + `tools/call` dispatch (rmcp 의 `#[tool_router]` 매크로 대신). `error_classify` 모듈을 `kebab-cli` → `kebab-app::error_wire` 로 promotion (UI crate 끼리 import 회피, facade 룰 준수). `ErrorV1` 에 `schema_version: String` 필드 추가 — kebab-mcp 의 직접 serialize 경로에서도 wire 정합. `KebabAppState` 가 `(Config, Option<PathBuf>)` carry — doctor tool 의 path-aware behavior 위해. ask + search arm 의 `tokio::task::spawn_blocking` wrap — `OllamaLanguageModel` 의 reqwest blocking client 가 async 안에서 panic 회피. capability flag `mcp_server` `false` → `true`. agent integration MVP 완성 — Claude Code / Cursor / OpenAI Agents 등 host-agnostic 사용 가능. spec: `tasks/p9/p9-fb-30-mcp-server.md`. design: `docs/superpowers/specs/2026-05-07-p9-fb-30-mcp-server-design.md`.
 - **P3-5 / P4-3 `--config` 누락** — `kebab-cli` 가 `--config <path>` 를 honor 하려면 `kebab_app::*_with_config` companion 을 호출해야 함. 두 번 같은 모양으로 회귀했음.
 - **P6-2 OCR 기본 엔진** — spec literal 의 Tesseract 가 시스템 dep 부담으로 거부됨, Ollama vision LM 으로 대체. `OcrEngine` trait 그대로라 future swap 가능.
diff --git a/README.md b/README.md
index 170439b..de5dabf 100644
--- a/README.md
+++ b/README.md
@@ -80,7 +80,9 @@ kebab doctor
 | `kebab reset [--all / --data-only / --vector-only / --config-only] [--yes]` | XDG 데이터 wipe. **Irreversible.** TTY 면 confirm prompt, 아니면 `--yes` 필수. `--vector-only` 는 SQLite `embedding_records` 도 함께 truncate (orphan 방지) |
 | `kebab eval run / compare` | golden query 회귀 측정 |
 | `kebab schema [--json]` | introspection — wire schemas / capabilities / models / stats 한 번에. `--json` 은 `schema.v1` wire; 사람 모드는 서식 출력. |
-| `kebab mcp` | MCP (Model Context Protocol) stdio server. agent host (Claude Code / Cursor / OpenAI Agents) 가 spawn 하여 tool 호출 (`search` / `ask` / `schema` / `doctor`). `--config` honor. |
+| `kebab ingest-file <path>` | 단일 파일 ingest (workspace 외부 가능). 바이트는 `<workspace.root>/_external/<hash12>.<ext>` 로 copy. `.kebabignore` 매치 시 stderr warn 후 진행 (explicit ingest 가 bypass intent). |
+| `kebab ingest-stdin --title <T> [--source-uri <URI>]` | stdin 의 markdown 본문 ingest. frontmatter (title + source_uri) 자동 prepend. v1 markdown only. |
+| `kebab mcp` | MCP (Model Context Protocol) stdio server. agent host (Claude Code / Cursor / OpenAI Agents) 가 spawn 하여 tool 호출 (`search` / `ask` / `schema` / `doctor` / `ingest_file` / `ingest_stdin`). `--config` honor. |
 
 모든 명령에 `--json` 플래그. 출력은 frozen wire schema v1 (`schema_version` 항상 포함, 예: `ingest_report.v1`, `ingest_progress.v1`, `search_hit.v1`, `answer.v1`, `doctor.v1`, `reset_report.v1`, `schema.v1`). `--json` 모드에서 fatal error 는 stderr 에 `error.v1` ndjson 으로 emit (exit code 0/1/2/3 unchanged).
 
@@ -164,9 +166,11 @@ config 예시는 [docs/SMOKE.md](docs/SMOKE.md) 의 `/tmp/kebab-smoke/config.tom
 - **MCP server** — stdio JSON-RPC 로 `kebab-app` facade 1:1 노출. `kebab mcp` 참조.
 - **HTTP wrapper** — `kebab serve --bind 127.0.0.1:7711` (P+, local-only 가치 신중).
 
-## MCP 사용 (Claude Code 예시)
+## MCP 사용
 
-`~/.claude/mcp.json` (또는 host 의 동등 위치):
+`kebab mcp` 가 stdio MCP server. 6 tool: `search` / `ask` / `schema` / `doctor` / `ingest_file` / `ingest_stdin`.
+
+Claude Code 빠른 등록 (`~/.claude/mcp.json` 또는 host 동등 위치):
 
 ```json
 {
@@ -179,7 +183,7 @@ config 예시는 [docs/SMOKE.md](docs/SMOKE.md) 의 `/tmp/kebab-smoke/config.tom
 }
 ```
 
-Claude Code 가 session 시작 시 `kebab mcp` 를 spawn — process 가 session 동안 살아 있어 SQLite / Lance / fastembed 가 hot. 4 tool: `search` (lexical/vector/hybrid 검색), `ask` (RAG 답변, optional `session_id` for multi-turn + optional `mode` override), `schema` (capability 조회), `doctor` (health check). 모든 tool 의 결과는 wire schema v1 JSON 으로 text content 안에 직렬화 — agent 가 parse 후 사용. tool dispatch 실패 (잘못된 config / 미초기화 KB 등) 는 `isError: true` + error.v1 content; refusal / no-hit / unhealthy 는 정상 응답 (semantic flag 으로 분기).
+자세한 사용법 (Cursor / OpenAI Agents / Copilot CLI config, per-tool 입출력 예시, troubleshooting, multi-turn ask + session 관리, performance / security) — **[docs/mcp-usage.md](docs/mcp-usage.md)** 참조.
 
 ## 비-목표
 
diff --git a/crates/kebab-app/Cargo.toml b/crates/kebab-app/Cargo.toml
index d163e9c..cc35d07 100644
--- a/crates/kebab-app/Cargo.toml
+++ b/crates/kebab-app/Cargo.toml
@@ -49,6 +49,9 @@ lru                  = { workspace = true }
 # `" foo "` collapse to one entry. Same crate kebab-normalize +
 # kebab-core already use, no version drift.
 unicode-normalization = "0.1"
+# p9-fb-31: GitignoreBuilder for .kebabignore matching in ingest_file_with_config.
+# Same version as kebab-source-fs (0.4) to avoid duplicate dep versions.
+ignore               = "0.4"
 
 [dev-dependencies]
 rusqlite             = { workspace = true }
diff --git a/crates/kebab-app/src/external.rs b/crates/kebab-app/src/external.rs
new file mode 100644
index 0000000..7a51990
--- /dev/null
+++ b/crates/kebab-app/src/external.rs
@@ -0,0 +1,253 @@
+//! Helpers for the `_external/` workspace subdirectory used by
+//! `ingest_file_with_config` and `ingest_stdin_with_config` (p9-fb-31).
+//!
+//! - `ensure_external_dir`: create `<workspace.root>/_external/` if absent.
+//! - `ensure_kebabignore_entry`: append `_external/` to `<workspace.root>/.kebabignore`
+//!   if missing — prevents subsequent `kebab ingest` workspace walks from
+//!   re-walking files that were imported via single-file ingest.
+//! - `copy_to_external`: write bytes to `_external/<blake3-12>.<ext>`, idempotent.
+//! - `inject_frontmatter`: prepend a YAML frontmatter block to a markdown body
+//!   string (used by `ingest_stdin_with_config`).
+
+use std::fs;
+use std::io::Write;
+use std::path::{Path, PathBuf};
+
+use anyhow::{Context, Result};
+
+pub const EXTERNAL_DIR: &str = "_external";
+const KEBABIGNORE_LINE: &str = "_external/";
+
+/// Ensure `<workspace_root>/_external/` exists. Returns the directory path.
+pub fn ensure_external_dir(workspace_root: &Path) -> Result<PathBuf> {
+    let dir = workspace_root.join(EXTERNAL_DIR);
+    fs::create_dir_all(&dir)
+        .with_context(|| format!("create _external dir at {}", dir.display()))?;
+    Ok(dir)
+}
+
+/// Append `_external/` line to `<workspace_root>/.kebabignore` if not already
+/// present. Idempotent — checks for the exact line before appending.
+pub fn ensure_kebabignore_entry(workspace_root: &Path) -> Result<()> {
+    let path = workspace_root.join(".kebabignore");
+    let existing = if path.exists() {
+        fs::read_to_string(&path)
+            .with_context(|| format!("read existing .kebabignore at {}", path.display()))?
+    } else {
+        String::new()
+    };
+    let already = existing
+        .lines()
+        .any(|line| line.trim() == KEBABIGNORE_LINE);
+    if already {
+        return Ok(());
+    }
+    let mut file = fs::OpenOptions::new()
+        .create(true)
+        .append(true)
+        .open(&path)
+        .with_context(|| format!("open .kebabignore for append at {}", path.display()))?;
+    if !existing.is_empty() && !existing.ends_with('\n') {
+        file.write_all(b"\n")?;
+    }
+    writeln!(file, "{}", KEBABIGNORE_LINE)?;
+    Ok(())
+}
+
+/// Copy bytes to `<external_dir>/<blake3-12>.<ext>`. Idempotent — if the
+/// destination file already exists with the expected hash, the existing
+/// file is reused (no second write). Returns the destination path.
+pub fn copy_to_external(
+    external_dir: &Path,
+    bytes: &[u8],
+    ext: &str,
+) -> Result<PathBuf> {
+    let hash = blake3::hash(bytes);
+    let hex = hash.to_hex();
+    let prefix = &hex.as_str()[..12];
+    let filename = format!("{prefix}.{ext}");
+    let dest = external_dir.join(&filename);
+    if !dest.exists() {
+        fs::write(&dest, bytes)
+            .with_context(|| format!("write external file at {}", dest.display()))?;
+    }
+    Ok(dest)
+}
+
+/// Prepend a YAML frontmatter block to a markdown body. Returns the wrapped
+/// markdown string. Errors if `body` already starts with `---` (the user
+/// should use `ingest_file_with_config` for files that already carry
+/// frontmatter).
+///
+/// Internal `yaml_quote` always uses double-quoted YAML form with backslash
+/// escapes for `"` / `\` / control chars — agent-supplied titles with
+/// special characters are safe.
+pub fn inject_frontmatter(
+    body: &str,
+    title: &str,
+    source_uri: Option<&str>,
+) -> Result<String> {
+    let head = body.trim_start();
+    if head.starts_with("---\n") || head.starts_with("---\r\n") || head.starts_with("---\r") {
+        anyhow::bail!(
+            "stdin already has frontmatter; use `kebab ingest-file` for files with metadata"
+        );
+    }
+    let title_yaml = yaml_quote(title);
+    let mut header = String::new();
+    header.push_str("---\n");
+    header.push_str(&format!("title: {title_yaml}\n"));
+    if let Some(uri) = source_uri {
+        let uri_yaml = yaml_quote(uri);
+        header.push_str(&format!("source_uri: {uri_yaml}\n"));
+    }
+    header.push_str("---\n\n");
+    header.push_str(body);
+    Ok(header)
+}
+
+/// YAML-quote a string. Always uses double-quoted form with backslash-escape
+/// for `"` and `\`. Defensive against agent-supplied titles that contain
+/// quotes / control chars.
+fn yaml_quote(s: &str) -> String {
+    let mut out = String::with_capacity(s.len() + 2);
+    out.push('"');
+    for c in s.chars() {
+        match c {
+            '"' => out.push_str("\\\""),
+            '\\' => out.push_str("\\\\"),
+            '\n' => out.push_str("\\n"),
+            '\r' => out.push_str("\\r"),
+            c if (c as u32) < 0x20 => out.push_str(&format!("\\u{:04x}", c as u32)),
+            c => out.push(c),
+        }
+    }
+    out.push('"');
+    out
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use tempfile::tempdir;
+
+    #[test]
+    fn ensure_external_dir_creates_dir() {
+        let dir = tempdir().unwrap();
+        let result = ensure_external_dir(dir.path()).unwrap();
+        assert_eq!(result, dir.path().join("_external"));
+        assert!(result.is_dir());
+    }
+
+    #[test]
+    fn ensure_external_dir_is_idempotent() {
+        let dir = tempdir().unwrap();
+        let _ = ensure_external_dir(dir.path()).unwrap();
+        let result = ensure_external_dir(dir.path()).unwrap();
+        assert!(result.is_dir());
+    }
+
+    #[test]
+    fn ensure_kebabignore_entry_creates_file_with_line() {
+        let dir = tempdir().unwrap();
+        ensure_kebabignore_entry(dir.path()).unwrap();
+        let content = fs::read_to_string(dir.path().join(".kebabignore")).unwrap();
+        assert!(content.lines().any(|l| l.trim() == "_external/"));
+    }
+
+    #[test]
+    fn ensure_kebabignore_entry_appends_to_existing() {
+        let dir = tempdir().unwrap();
+        fs::write(dir.path().join(".kebabignore"), "*.tmp\n").unwrap();
+        ensure_kebabignore_entry(dir.path()).unwrap();
+        let content = fs::read_to_string(dir.path().join(".kebabignore")).unwrap();
+        let lines: Vec<&str> = content.lines().collect();
+        assert!(lines.contains(&"*.tmp"));
+        assert!(lines.contains(&"_external/"));
+    }
+
+    #[test]
+    fn ensure_kebabignore_entry_idempotent() {
+        let dir = tempdir().unwrap();
+        ensure_kebabignore_entry(dir.path()).unwrap();
+        ensure_kebabignore_entry(dir.path()).unwrap();
+        let content = fs::read_to_string(dir.path().join(".kebabignore")).unwrap();
+        let count = content.lines().filter(|l| l.trim() == "_external/").count();
+        assert_eq!(count, 1, "should not duplicate");
+    }
+
+    #[test]
+    fn ensure_kebabignore_entry_handles_missing_trailing_newline() {
+        let dir = tempdir().unwrap();
+        fs::write(dir.path().join(".kebabignore"), "*.tmp").unwrap(); // no \n
+        ensure_kebabignore_entry(dir.path()).unwrap();
+        let content = fs::read_to_string(dir.path().join(".kebabignore")).unwrap();
+        let lines: Vec<&str> = content.lines().collect();
+        assert!(lines.contains(&"*.tmp"));
+        assert!(lines.contains(&"_external/"));
+    }
+
+    #[test]
+    fn copy_to_external_writes_with_hash_prefix_filename() {
+        let dir = tempdir().unwrap();
+        let ext_dir = ensure_external_dir(dir.path()).unwrap();
+        let path = copy_to_external(&ext_dir, b"hello", "md").unwrap();
+        assert!(path.exists());
+        assert!(path.file_name().unwrap().to_string_lossy().ends_with(".md"));
+        let stem = path.file_stem().unwrap().to_string_lossy();
+        assert_eq!(stem.len(), 12);
+    }
+
+    #[test]
+    fn copy_to_external_is_idempotent_for_same_bytes() {
+        let dir = tempdir().unwrap();
+        let ext_dir = ensure_external_dir(dir.path()).unwrap();
+        let p1 = copy_to_external(&ext_dir, b"hello", "md").unwrap();
+        let p2 = copy_to_external(&ext_dir, b"hello", "md").unwrap();
+        assert_eq!(p1, p2);
+    }
+
+    #[test]
+    fn copy_to_external_different_bytes_produce_different_filenames() {
+        let dir = tempdir().unwrap();
+        let ext_dir = ensure_external_dir(dir.path()).unwrap();
+        let p1 = copy_to_external(&ext_dir, b"hello", "md").unwrap();
+        let p2 = copy_to_external(&ext_dir, b"world", "md").unwrap();
+        assert_ne!(p1, p2);
+    }
+
+    #[test]
+    fn inject_frontmatter_basic() {
+        let out = inject_frontmatter("## Body", "Article X", None).unwrap();
+        assert!(out.starts_with("---\ntitle: \"Article X\"\n---\n\n## Body"));
+    }
+
+    #[test]
+    fn inject_frontmatter_with_source_uri() {
+        let out = inject_frontmatter("## Body", "X", Some("https://example.com/x")).unwrap();
+        assert!(out.contains("title: \"X\""));
+        assert!(out.contains("source_uri: \"https://example.com/x\""));
+        assert!(out.contains("\n## Body"));
+    }
+
+    #[test]
+    fn inject_frontmatter_errors_on_existing_frontmatter() {
+        let body = "---\ntitle: Existing\n---\n\n## Body";
+        let err = inject_frontmatter(body, "New", None).unwrap_err();
+        assert!(err.to_string().contains("already has frontmatter"));
+    }
+
+    #[test]
+    fn inject_frontmatter_errors_on_existing_frontmatter_crlf() {
+        let body = "---\r\ntitle: Existing\r\n---\r\n\r\n## Body";
+        let err = inject_frontmatter(body, "New", None).unwrap_err();
+        assert!(err.to_string().contains("already has frontmatter"));
+    }
+
+    #[test]
+    fn yaml_quote_escapes_quotes_and_backslashes() {
+        assert_eq!(yaml_quote("hello \"world\""), "\"hello \\\"world\\\"\"");
+        assert_eq!(yaml_quote("path\\to"), "\"path\\\\to\"");
+        assert_eq!(yaml_quote("line\nbreak"), "\"line\\nbreak\"");
+    }
+}
diff --git a/crates/kebab-app/src/lib.rs b/crates/kebab-app/src/lib.rs
index 58c4062..fa5b242 100644
--- a/crates/kebab-app/src/lib.rs
+++ b/crates/kebab-app/src/lib.rs
@@ -58,6 +58,7 @@ mod app;
 pub mod doctor_signal;
 pub mod error_signal;
 pub mod error_wire;
+pub mod external;
 pub mod ingest_progress;
 pub mod logging;
 pub mod reset;
@@ -1874,3 +1875,143 @@ pub fn doctor_with_config_path(config_path: Option<&std::path::Path>) -> anyhow:
 pub fn doctor() -> anyhow::Result<DoctorReport> {
     doctor_with_config_path(None)
 }
+
+/// Single-file ingest (p9-fb-31). Copies the file to
+/// `<workspace.root>/_external/<blake3-12>.<ext>` and runs the
+/// per-medium ingest pipeline on that single asset. Returns an
+/// `IngestReport` with `scanned: 1` (and either `new: 1` or
+/// `unchanged: 1` depending on whether the content hash + version
+/// cascade match an existing doc — incremental ingest from p9-fb-23).
+///
+/// `path` may point inside or outside the workspace.
+///
+/// `.kebabignore` patterns matching `path` are bypassed with a stderr
+/// `warn:` line — explicit ingest is intent.
+#[doc(hidden)]
+pub fn ingest_file_with_config(
+    config: kebab_config::Config,
+    path: &std::path::Path,
+) -> anyhow::Result<IngestReport> {
+    if !path.exists() {
+        anyhow::bail!("ingest-file: source path does not exist: {}", path.display());
+    }
+    if !path.is_file() {
+        anyhow::bail!("ingest-file: not a regular file: {}", path.display());
+    }
+
+    let ext_raw = path
+        .extension()
+        .and_then(|e| e.to_str())
+        .ok_or_else(|| anyhow::anyhow!("ingest-file: source has no extension: {}", path.display()))?;
+    let ext = ext_raw.to_lowercase();
+
+    const SUPPORTED_EXTS: &[&str] = &["md", "pdf", "png", "jpg", "jpeg"];
+    if !SUPPORTED_EXTS.contains(&ext.as_str()) {
+        anyhow::bail!(
+            "ingest-file: unsupported extension `.{}` (supported: {:?})",
+            ext, SUPPORTED_EXTS
+        );
+    }
+
+    let bytes = std::fs::read(path)
+        .with_context(|| format!("ingest-file: read source {}", path.display()))?;
+
+    let workspace_root = config.resolve_workspace_root();
+
+    // .kebabignore check — warn but continue.
+    let ignore_match = check_kebabignore_match(&workspace_root, path);
+    if ignore_match {
+        eprintln!(
+            "warn: {} matches .kebabignore patterns; proceeding (explicit ingest bypasses ignore)",
+            path.display()
+        );
+    }
+
+    // Set up _external/ dir + auto-ignore line.
+    let external_dir = crate::external::ensure_external_dir(&workspace_root)
+        .context("ingest-file: ensure _external/ dir")?;
+    crate::external::ensure_kebabignore_entry(&workspace_root)
+        .context("ingest-file: append _external/ to .kebabignore")?;
+
+    // Copy bytes to _external/<hash>.<ext>.
+    let dest = crate::external::copy_to_external(&external_dir, &bytes, &ext)
+        .context("ingest-file: copy to _external")?;
+
+    // Build a SourceScope that targets _external/ with include filter
+    // restricting walk to the single dest filename.
+    let filename = dest
+        .file_name()
+        .ok_or_else(|| anyhow::anyhow!("ingest-file: dest has no filename"))?
+        .to_string_lossy()
+        .into_owned();
+    let scope = kebab_core::SourceScope {
+        root: external_dir.clone(),
+        include: vec![filename],
+        exclude: config.workspace.exclude.clone(),
+    };
+
+    let opts = IngestOpts::default();
+    ingest_with_config_opts(config, scope, /* summary_only = */ false, opts)
+}
+
+/// Stdin ingest (p9-fb-31, v1 markdown only). Prepends a YAML
+/// frontmatter block (`title` + optional `source_uri`) to `body`,
+/// writes the wrapped markdown to `_external/<hash12>.md`, and runs
+/// `ingest_file_with_config` on the resulting file.
+///
+/// Errors if `body` already starts with `---` (the user should call
+/// `ingest_file_with_config` directly for files that already carry
+/// frontmatter).
+#[doc(hidden)]
+pub fn ingest_stdin_with_config(
+    config: kebab_config::Config,
+    body: &str,
+    title: &str,
+    source_uri: Option<&str>,
+) -> anyhow::Result<IngestReport> {
+    let wrapped = crate::external::inject_frontmatter(body, title, source_uri)?;
+
+    let workspace_root = config.resolve_workspace_root();
+    // Note: ensure_external_dir + ensure_kebabignore_entry + copy_to_external
+    // are called here AND inside ingest_file_with_config. All three are
+    // idempotent; the redundancy is intentional — keeping stdin's wrapped
+    // bytes accessible by `ingest_file_with_config` requires the dest path
+    // to exist. The ~ms double-stat overhead is negligible at v1 scale.
+    let external_dir = crate::external::ensure_external_dir(&workspace_root)?;
+    crate::external::ensure_kebabignore_entry(&workspace_root)?;
+
+    let dest = crate::external::copy_to_external(
+        &external_dir,
+        wrapped.as_bytes(),
+        "md",
+    )?;
+
+    ingest_file_with_config(config, &dest)
+}
+
+/// Returns true if `source_path` matches any `.kebabignore` pattern
+/// rooted at `workspace_root`. Used by `ingest_file_with_config` to
+/// emit a stderr warn before bypassing the ignore.
+fn check_kebabignore_match(workspace_root: &std::path::Path, source_path: &std::path::Path) -> bool {
+    let kebabignore = workspace_root.join(".kebabignore");
+    if !kebabignore.exists() {
+        return false;
+    }
+    let text = match std::fs::read_to_string(&kebabignore) {
+        Ok(s) => s,
+        Err(_) => return false,
+    };
+    let mut builder = ignore::gitignore::GitignoreBuilder::new(workspace_root);
+    for line in text.lines() {
+        let line = line.trim();
+        if line.is_empty() || line.starts_with('#') {
+            continue;
+        }
+        let _ = builder.add_line(None, line);
+    }
+    let matcher = match builder.build() {
+        Ok(m) => m,
+        Err(_) => return false,
+    };
+    matcher.matched(source_path, source_path.is_dir()).is_ignore()
+}
diff --git a/crates/kebab-app/tests/ingest_file.rs b/crates/kebab-app/tests/ingest_file.rs
new file mode 100644
index 0000000..85255f6
--- /dev/null
+++ b/crates/kebab-app/tests/ingest_file.rs
@@ -0,0 +1,111 @@
+//! Integration: kebab_app::ingest_file_with_config copies external file
+//! to _external/, ingests as single asset, idempotent on second call.
+
+use std::fs;
+
+use kebab_config::Config;
+
+#[test]
+fn ingest_file_copies_external_md_and_reports_new() {
+    let dir = tempfile::tempdir().unwrap();
+    let workspace = dir.path().join("notes");
+    let data = dir.path().join("data");
+    fs::create_dir_all(&workspace).unwrap();
+    fs::create_dir_all(&data).unwrap();
+
+    let mut cfg = Config::defaults();
+    cfg.workspace.root = workspace.to_string_lossy().into_owned();
+    cfg.storage.data_dir = data.to_string_lossy().into_owned();
+    cfg.models.embedding.provider = "none".to_string();
+    cfg.models.embedding.dimensions = 0;
+
+    // Source file outside the workspace.
+    let external_src = dir.path().join("source.md");
+    fs::write(&external_src, "# Hello\n\nbody.").unwrap();
+
+    let report = kebab_app::ingest_file_with_config(cfg.clone(), &external_src).unwrap();
+    assert_eq!(report.scanned, 1, "{report:?}");
+    assert_eq!(report.new, 1, "{report:?}");
+    assert_eq!(report.unchanged, 0, "{report:?}");
+
+    // _external/ dir created, file copied with hash prefix.
+    let ext_dir = workspace.join("_external");
+    assert!(ext_dir.is_dir());
+    let entries: Vec<_> = fs::read_dir(&ext_dir)
+        .unwrap()
+        .filter_map(|e| e.ok())
+        .collect();
+    assert_eq!(entries.len(), 1, "exactly one file in _external/");
+    let name = entries[0].file_name().to_string_lossy().into_owned();
+    assert!(name.ends_with(".md"));
+
+    // .kebabignore has _external/ line.
+    let ki = fs::read_to_string(workspace.join(".kebabignore")).unwrap();
+    assert!(ki.lines().any(|l| l.trim() == "_external/"));
+}
+
+#[test]
+fn ingest_file_idempotent_on_second_call() {
+    let dir = tempfile::tempdir().unwrap();
+    let workspace = dir.path().join("notes");
+    let data = dir.path().join("data");
+    fs::create_dir_all(&workspace).unwrap();
+    fs::create_dir_all(&data).unwrap();
+
+    let mut cfg = Config::defaults();
+    cfg.workspace.root = workspace.to_string_lossy().into_owned();
+    cfg.storage.data_dir = data.to_string_lossy().into_owned();
+    cfg.models.embedding.provider = "none".to_string();
+    cfg.models.embedding.dimensions = 0;
+
+    let src = dir.path().join("doc.md");
+    fs::write(&src, "# A\n\nbody.").unwrap();
+
+    let r1 = kebab_app::ingest_file_with_config(cfg.clone(), &src).unwrap();
+    assert_eq!(r1.new, 1);
+
+    let r2 = kebab_app::ingest_file_with_config(cfg.clone(), &src).unwrap();
+    assert_eq!(r2.new, 0, "{r2:?}");
+    assert_eq!(r2.unchanged, 1, "{r2:?}");
+}
+
+#[test]
+fn ingest_file_errors_on_missing_path() {
+    let dir = tempfile::tempdir().unwrap();
+    let workspace = dir.path().join("notes");
+    let data = dir.path().join("data");
+    fs::create_dir_all(&workspace).unwrap();
+    fs::create_dir_all(&data).unwrap();
+
+    let mut cfg = Config::defaults();
+    cfg.workspace.root = workspace.to_string_lossy().into_owned();
+    cfg.storage.data_dir = data.to_string_lossy().into_owned();
+    cfg.models.embedding.provider = "none".to_string();
+    cfg.models.embedding.dimensions = 0;
+
+    let nonexistent = dir.path().join("nope.md");
+    let err = kebab_app::ingest_file_with_config(cfg, &nonexistent).unwrap_err();
+    assert!(err.to_string().contains("does not exist"), "{err}");
+}
+
+#[test]
+fn ingest_file_errors_on_unsupported_extension() {
+    let dir = tempfile::tempdir().unwrap();
+    let workspace = dir.path().join("notes");
+    let data = dir.path().join("data");
+    fs::create_dir_all(&workspace).unwrap();
+    fs::create_dir_all(&data).unwrap();
+
+    let mut cfg = Config::defaults();
+    cfg.workspace.root = workspace.to_string_lossy().into_owned();
+    cfg.storage.data_dir = data.to_string_lossy().into_owned();
+    cfg.models.embedding.provider = "none".to_string();
+    cfg.models.embedding.dimensions = 0;
+
+    let docx = dir.path().join("doc.docx");
+    fs::write(&docx, b"fake docx bytes").unwrap();
+
+    let err = kebab_app::ingest_file_with_config(cfg, &docx).unwrap_err();
+    assert!(err.to_string().contains("unsupported extension"), "{err}");
+    assert!(err.to_string().contains(".docx") || err.to_string().contains("docx"), "{err}");
+}
diff --git a/crates/kebab-app/tests/ingest_stdin.rs b/crates/kebab-app/tests/ingest_stdin.rs
new file mode 100644
index 0000000..0eeafe7
--- /dev/null
+++ b/crates/kebab-app/tests/ingest_stdin.rs
@@ -0,0 +1,78 @@
+//! Integration: kebab_app::ingest_stdin_with_config injects frontmatter,
+//! writes to _external/, ingests as single asset.
+
+use std::fs;
+
+use kebab_config::Config;
+
+fn fresh_cfg(dir: &std::path::Path) -> Config {
+    let workspace = dir.join("notes");
+    let data = dir.join("data");
+    fs::create_dir_all(&workspace).unwrap();
+    fs::create_dir_all(&data).unwrap();
+
+    let mut cfg = Config::defaults();
+    cfg.workspace.root = workspace.to_string_lossy().into_owned();
+    cfg.storage.data_dir = data.to_string_lossy().into_owned();
+    cfg.models.embedding.provider = "none".to_string();
+    cfg.models.embedding.dimensions = 0;
+    cfg
+}
+
+#[test]
+fn ingest_stdin_writes_frontmatter_and_reports_new() {
+    let dir = tempfile::tempdir().unwrap();
+    let cfg = fresh_cfg(dir.path());
+
+    let report = kebab_app::ingest_stdin_with_config(
+        cfg.clone(),
+        "## Body content\n\nMore.",
+        "Article X",
+        Some("https://example.com/x"),
+    ).unwrap();
+    assert_eq!(report.new, 1, "{report:?}");
+
+    // _external/ contains exactly one .md file with frontmatter.
+    let ext_dir = std::path::PathBuf::from(&cfg.workspace.root).join("_external");
+    let entries: Vec<_> = fs::read_dir(&ext_dir).unwrap()
+        .filter_map(|e| e.ok())
+        .collect();
+    assert_eq!(entries.len(), 1);
+    let content = fs::read_to_string(entries[0].path()).unwrap();
+    assert!(content.starts_with("---\n"));
+    assert!(content.contains("title: \"Article X\""));
+    assert!(content.contains("source_uri: \"https://example.com/x\""));
+    assert!(content.contains("## Body content"));
+}
+
+#[test]
+fn ingest_stdin_without_source_uri() {
+    let dir = tempfile::tempdir().unwrap();
+    let cfg = fresh_cfg(dir.path());
+
+    let report = kebab_app::ingest_stdin_with_config(
+        cfg.clone(),
+        "## Body",
+        "Title",
+        None,
+    ).unwrap();
+    assert_eq!(report.new, 1);
+
+    let ext_dir = std::path::PathBuf::from(&cfg.workspace.root).join("_external");
+    let entries: Vec<_> = fs::read_dir(&ext_dir).unwrap()
+        .filter_map(|e| e.ok())
+        .collect();
+    let content = fs::read_to_string(entries[0].path()).unwrap();
+    assert!(content.contains("title: \"Title\""));
+    assert!(!content.contains("source_uri"));
+}
+
+#[test]
+fn ingest_stdin_errors_on_existing_frontmatter() {
+    let dir = tempfile::tempdir().unwrap();
+    let cfg = fresh_cfg(dir.path());
+
+    let body = "---\ntitle: Already\n---\n\n## Body";
+    let err = kebab_app::ingest_stdin_with_config(cfg, body, "New", None).unwrap_err();
+    assert!(err.to_string().contains("already has frontmatter"), "{err}");
+}
diff --git a/crates/kebab-cli/src/main.rs b/crates/kebab-cli/src/main.rs
index db0f4b1..6c7a159 100644
--- a/crates/kebab-cli/src/main.rs
+++ b/crates/kebab-cli/src/main.rs
@@ -4,6 +4,7 @@
 use std::path::PathBuf;
 use std::process::ExitCode;
 
+use anyhow::Context;
 use clap::{Parser, Subcommand};
 
 use kebab_app::doctor_signal::{DoctorUnhealthy, NoHitSignal, RefusalSignal};
@@ -193,6 +194,24 @@ enum Cmd {
     /// agent hosts (Claude Code / Cursor / OpenAI Agents) to call kebab
     /// tools (search / ask / schema / doctor).
     Mcp,
+
+    /// Ingest a single file (workspace external paths allowed).
+    /// Bytes are copied into `<workspace.root>/_external/<hash>.<ext>`.
+    IngestFile {
+        /// File path to ingest.
+        path: std::path::PathBuf,
+    },
+
+    /// Ingest markdown content from stdin. v1 markdown only.
+    /// Frontmatter (title + source_uri) is auto-injected.
+    IngestStdin {
+        /// Title — required, written to frontmatter.
+        #[arg(long)]
+        title: String,
+        /// Source URI — optional, written to frontmatter when present.
+        #[arg(long)]
+        source_uri: Option<String>,
+    },
 }
 
 #[derive(Subcommand, Debug)]
@@ -745,6 +764,48 @@ fn run(cli: &Cli) -> anyhow::Result<()> {
             }
         },
 
+        Cmd::IngestFile { path } => {
+            let cfg = kebab_config::Config::load(cli.config.as_deref())?;
+            let report = kebab_app::ingest_file_with_config(cfg, path)?;
+            if cli.json {
+                let v = wire::wire_ingest(&report);
+                println!("{}", serde_json::to_string(&v)?);
+            } else {
+                println!(
+                    "ingest-file: scanned={} new={} updated={} unchanged={} skipped={} errors={}",
+                    report.scanned, report.new, report.updated,
+                    report.unchanged, report.skipped, report.errors
+                );
+            }
+            Ok(())
+        }
+
+        Cmd::IngestStdin { title, source_uri } => {
+            use std::io::Read;
+            let mut body = String::new();
+            std::io::stdin()
+                .read_to_string(&mut body)
+                .context("kebab ingest-stdin: read stdin")?;
+            let cfg = kebab_config::Config::load(cli.config.as_deref())?;
+            let report = kebab_app::ingest_stdin_with_config(
+                cfg,
+                &body,
+                title,
+                source_uri.as_deref(),
+            )?;
+            if cli.json {
+                let v = wire::wire_ingest(&report);
+                println!("{}", serde_json::to_string(&v)?);
+            } else {
+                println!(
+                    "ingest-stdin: scanned={} new={} updated={} unchanged={} skipped={} errors={}",
+                    report.scanned, report.new, report.updated,
+                    report.unchanged, report.skipped, report.errors
+                );
+            }
+            Ok(())
+        }
+
         Cmd::Mcp => {
             let cfg = kebab_config::Config::load(cli.config.as_deref())?;
             kebab_mcp::serve_stdio(cfg, cli.config.clone())
diff --git a/crates/kebab-cli/tests/cli_ingest_file.rs b/crates/kebab-cli/tests/cli_ingest_file.rs
new file mode 100644
index 0000000..5f81dbd
--- /dev/null
+++ b/crates/kebab-cli/tests/cli_ingest_file.rs
@@ -0,0 +1,92 @@
+//! Integration: spawn `kebab ingest-file <path>` and verify ingest_report.v1.
+
+use std::fs;
+use std::process::Command;
+
+#[test]
+fn cli_ingest_file_emits_ingest_report_v1() {
+    let dir = tempfile::tempdir().unwrap();
+    let workspace = dir.path().join("notes");
+    let data = dir.path().join("data");
+    fs::create_dir_all(&workspace).unwrap();
+    fs::create_dir_all(&data).unwrap();
+
+    let cfg_path = dir.path().join("config.toml");
+    fs::write(
+        &cfg_path,
+        format!(
+            r#"schema_version = 1
+
+[workspace]
+root = "{workspace}"
+exclude = [".git/**"]
+
+[storage]
+data_dir = "{data}"
+sqlite = "{{data_dir}}/kebab.sqlite"
+vector_dir = "{{data_dir}}/lancedb"
+asset_dir = "{{data_dir}}/assets"
+artifact_dir = "{{data_dir}}/artifacts"
+model_dir = "{{data_dir}}/models"
+runs_dir = "{{data_dir}}/runs"
+copy_threshold_mb = 100
+
+[indexing]
+max_parallel_extractors = 2
+max_parallel_embeddings = 1
+watch_filesystem = false
+
+[chunking]
+target_tokens = 500
+overlap_tokens = 80
+respect_markdown_headings = true
+chunker_version = "md-heading-v1"
+
+[models.embedding]
+provider = "none"
+model = "none"
+version = "v0"
+dimensions = 0
+batch_size = 1
+
+[models.llm]
+provider = "ollama"
+model = "none"
+context_tokens = 4096
+endpoint = "http://127.0.0.1:11434"
+temperature = 0.0
+seed = 0
+
+[search]
+default_k = 10
+hybrid_fusion = "rrf"
+rrf_k = 60
+snippet_chars = 220
+
+[rag]
+prompt_template_version = "rag-v1"
+score_gate = 0.30
+explain_default = false
+max_context_tokens = 8000
+"#,
+            workspace = workspace.display(),
+            data = data.display(),
+        ),
+    ).unwrap();
+
+    let src = dir.path().join("doc.md");
+    fs::write(&src, "# A\n\nbody.").unwrap();
+
+    let bin = env!("CARGO_BIN_EXE_kebab");
+    let out = Command::new(bin)
+        .args(["--json", "--config", cfg_path.to_str().unwrap(), "ingest-file"])
+        .arg(&src)
+        .output()
+        .unwrap();
+    assert!(out.status.success(), "stderr: {}", String::from_utf8_lossy(&out.stderr));
+
+    let stdout = String::from_utf8_lossy(&out.stdout);
+    let v: serde_json::Value = serde_json::from_str(stdout.trim()).unwrap();
+    assert_eq!(v.get("schema_version").and_then(|s| s.as_str()), Some("ingest_report.v1"));
+    assert_eq!(v.get("new").and_then(|n| n.as_u64()), Some(1));
+}
diff --git a/crates/kebab-cli/tests/cli_ingest_stdin.rs b/crates/kebab-cli/tests/cli_ingest_stdin.rs
new file mode 100644
index 0000000..d040350
--- /dev/null
+++ b/crates/kebab-cli/tests/cli_ingest_stdin.rs
@@ -0,0 +1,100 @@
+//! Integration: spawn `kebab ingest-stdin --title X` with stdin pipe.
+
+use std::fs;
+use std::io::Write;
+use std::process::{Command, Stdio};
+
+#[test]
+fn cli_ingest_stdin_emits_ingest_report_v1() {
+    let dir = tempfile::tempdir().unwrap();
+    let workspace = dir.path().join("notes");
+    let data = dir.path().join("data");
+    fs::create_dir_all(&workspace).unwrap();
+    fs::create_dir_all(&data).unwrap();
+
+    let cfg_path = dir.path().join("config.toml");
+    fs::write(
+        &cfg_path,
+        format!(
+            r#"schema_version = 1
+
+[workspace]
+root = "{workspace}"
+exclude = [".git/**"]
+
+[storage]
+data_dir = "{data}"
+sqlite = "{{data_dir}}/kebab.sqlite"
+vector_dir = "{{data_dir}}/lancedb"
+asset_dir = "{{data_dir}}/assets"
+artifact_dir = "{{data_dir}}/artifacts"
+model_dir = "{{data_dir}}/models"
+runs_dir = "{{data_dir}}/runs"
+copy_threshold_mb = 100
+
+[indexing]
+max_parallel_extractors = 2
+max_parallel_embeddings = 1
+watch_filesystem = false
+
+[chunking]
+target_tokens = 500
+overlap_tokens = 80
+respect_markdown_headings = true
+chunker_version = "md-heading-v1"
+
+[models.embedding]
+provider = "none"
+model = "none"
+version = "v0"
+dimensions = 0
+batch_size = 1
+
+[models.llm]
+provider = "ollama"
+model = "none"
+context_tokens = 4096
+endpoint = "http://127.0.0.1:11434"
+temperature = 0.0
+seed = 0
+
+[search]
+default_k = 10
+hybrid_fusion = "rrf"
+rrf_k = 60
+snippet_chars = 220
+
+[rag]
+prompt_template_version = "rag-v1"
+score_gate = 0.30
+explain_default = false
+max_context_tokens = 8000
+"#,
+            workspace = workspace.display(),
+            data = data.display(),
+        ),
+    ).unwrap();
+
+    let bin = env!("CARGO_BIN_EXE_kebab");
+    let mut child = Command::new(bin)
+        .args([
+            "--json", "--config", cfg_path.to_str().unwrap(),
+            "ingest-stdin", "--title", "X",
+        ])
+        .stdin(Stdio::piped())
+        .stdout(Stdio::piped())
+        .stderr(Stdio::piped())
+        .spawn()
+        .unwrap();
+    {
+        let stdin = child.stdin.as_mut().unwrap();
+        stdin.write_all(b"## Body\n\nbody text.\n").unwrap();
+    }
+    let out = child.wait_with_output().unwrap();
+    assert!(out.status.success(), "stderr: {}", String::from_utf8_lossy(&out.stderr));
+
+    let stdout = String::from_utf8_lossy(&out.stdout);
+    let v: serde_json::Value = serde_json::from_str(stdout.trim()).unwrap();
+    assert_eq!(v.get("schema_version").and_then(|s| s.as_str()), Some("ingest_report.v1"));
+    assert_eq!(v.get("new").and_then(|n| n.as_u64()), Some(1));
+}
diff --git a/crates/kebab-cli/tests/cli_mcp_smoke.rs b/crates/kebab-cli/tests/cli_mcp_smoke.rs
index bdfe335..1c0b07b 100644
--- a/crates/kebab-cli/tests/cli_mcp_smoke.rs
+++ b/crates/kebab-cli/tests/cli_mcp_smoke.rs
@@ -66,8 +66,8 @@ fn cli_mcp_initialize_then_tools_list() {
         .expect("tools/list result.tools must be an array");
     assert_eq!(
         tools.len(),
-        4,
-        "expected 4 tools (schema, doctor, search, ask), got {}: {list}",
+        6,
+        "expected 6 tools (schema, doctor, search, ask, ingest_file, ingest_stdin), got {}: {list}",
         tools.len()
     );
 
diff --git a/crates/kebab-mcp/src/lib.rs b/crates/kebab-mcp/src/lib.rs
index a190673..fc6a2a4 100644
--- a/crates/kebab-mcp/src/lib.rs
+++ b/crates/kebab-mcp/src/lib.rs
@@ -1,6 +1,6 @@
-//! MCP (Model Context Protocol) server over stdio. Exposes 4 read-only
-//! tools (`search` / `ask` / `schema` / `doctor`) backed by `kebab-app`
-//! facade methods. Used by `kebab-cli`'s `Cmd::Mcp` arm.
+//! MCP (Model Context Protocol) server over stdio. Exposes 6 tools
+//! (`search` / `ask` / `schema` / `doctor` / `ingest_file` / `ingest_stdin`)
+//! backed by `kebab-app` facade methods. Used by `kebab-cli`'s `Cmd::Mcp` arm.
 //!
 //! See spec `docs/superpowers/specs/2026-05-07-p9-fb-30-mcp-server-design.md`.
 
@@ -51,6 +51,16 @@ pub fn build_tools_vec() -> Vec<Tool> {
             "RAG question answering over the knowledge base. Returns answer.v1 JSON. Pass session_id for multi-turn context.",
             schema_for_type::<tools::ask::AskInput>(),
         ),
+        Tool::new(
+            "ingest_file",
+            "Ingest a single file (path) into the knowledge base. Workspace external paths allowed — bytes are copied into _external/.",
+            schema_for_type::<tools::ingest_file::IngestFileInput>(),
+        ),
+        Tool::new(
+            "ingest_stdin",
+            "Ingest markdown content into the knowledge base. v1 markdown only. Frontmatter (title + source_uri) auto-injected.",
+            schema_for_type::<tools::ingest_stdin::IngestStdinInput>(),
+        ),
     ]
 }
 
@@ -133,6 +143,20 @@ impl ServerHandler for KebabHandler {
                 })
                 .await
             }
+            "ingest_file" => {
+                let args = request.arguments.unwrap_or_default();
+                self.spawn_tool(args, |state, input| {
+                    tools::ingest_file::handle(&state, input)
+                })
+                .await
+            }
+            "ingest_stdin" => {
+                let args = request.arguments.unwrap_or_default();
+                self.spawn_tool(args, |state, input| {
+                    tools::ingest_stdin::handle(&state, input)
+                })
+                .await
+            }
             _other => Err(ErrorData::method_not_found::<
                 rmcp::model::CallToolRequestMethod,
             >()),
diff --git a/crates/kebab-mcp/src/tools/ingest_file.rs b/crates/kebab-mcp/src/tools/ingest_file.rs
new file mode 100644
index 0000000..0bad2a6
--- /dev/null
+++ b/crates/kebab-mcp/src/tools/ingest_file.rs
@@ -0,0 +1,39 @@
+//! `ingest_file` tool — wraps `kebab_app::ingest_file_with_config`.
+//! Input: { path }. Output: ingest_report.v1 JSON.
+
+use std::path::PathBuf;
+
+use rmcp::model::CallToolResult;
+use schemars::JsonSchema;
+use serde::{Deserialize, Serialize};
+
+use crate::error::{to_tool_error, to_tool_success};
+use crate::state::KebabAppState;
+
+#[derive(Debug, Deserialize, Serialize, JsonSchema)]
+pub struct IngestFileInput {
+    /// Absolute or relative path to the file to ingest. Workspace external
+    /// paths are allowed — bytes are copied into `_external/`.
+    pub path: String,
+}
+
+pub fn handle(state: &KebabAppState, input: IngestFileInput) -> CallToolResult {
+    let cfg_clone = (*state.config).clone();
+    let path = PathBuf::from(input.path);
+    match kebab_app::ingest_file_with_config(cfg_clone, &path) {
+        Ok(report) => match serde_json::to_value(&report) {
+            Ok(mut v) => {
+                if let serde_json::Value::Object(ref mut map) = v {
+                    map.entry("schema_version".to_string())
+                        .or_insert_with(|| serde_json::Value::String("ingest_report.v1".to_string()));
+                }
+                match serde_json::to_string(&v) {
+                    Ok(json) => to_tool_success(json),
+                    Err(e) => to_tool_error(&anyhow::anyhow!(e)),
+                }
+            }
+            Err(e) => to_tool_error(&anyhow::anyhow!(e)),
+        },
+        Err(e) => to_tool_error(&e),
+    }
+}
diff --git a/crates/kebab-mcp/src/tools/ingest_stdin.rs b/crates/kebab-mcp/src/tools/ingest_stdin.rs
new file mode 100644
index 0000000..5957711
--- /dev/null
+++ b/crates/kebab-mcp/src/tools/ingest_stdin.rs
@@ -0,0 +1,44 @@
+//! `ingest_stdin` tool — wraps `kebab_app::ingest_stdin_with_config`.
+//! Input: { content, title, source_uri? }. Output: ingest_report.v1 JSON.
+
+use rmcp::model::CallToolResult;
+use schemars::JsonSchema;
+use serde::{Deserialize, Serialize};
+
+use crate::error::{to_tool_error, to_tool_success};
+use crate::state::KebabAppState;
+
+#[derive(Debug, Deserialize, Serialize, JsonSchema)]
+pub struct IngestStdinInput {
+    /// Markdown body content. v1 supports markdown only.
+    pub content: String,
+    /// Title for frontmatter injection.
+    pub title: String,
+    /// Optional source URI (e.g. https URL agent fetched from).
+    pub source_uri: Option<String>,
+}
+
+pub fn handle(state: &KebabAppState, input: IngestStdinInput) -> CallToolResult {
+    let cfg_clone = (*state.config).clone();
+    match kebab_app::ingest_stdin_with_config(
+        cfg_clone,
+        &input.content,
+        &input.title,
+        input.source_uri.as_deref(),
+    ) {
+        Ok(report) => match serde_json::to_value(&report) {
+            Ok(mut v) => {
+                if let serde_json::Value::Object(ref mut map) = v {
+                    map.entry("schema_version".to_string())
+                        .or_insert_with(|| serde_json::Value::String("ingest_report.v1".to_string()));
+                }
+                match serde_json::to_string(&v) {
+                    Ok(json) => to_tool_success(json),
+                    Err(e) => to_tool_error(&anyhow::anyhow!(e)),
+                }
+            }
+            Err(e) => to_tool_error(&anyhow::anyhow!(e)),
+        },
+        Err(e) => to_tool_error(&e),
+    }
+}
diff --git a/crates/kebab-mcp/src/tools/mod.rs b/crates/kebab-mcp/src/tools/mod.rs
index 3e3d898..087d630 100644
--- a/crates/kebab-mcp/src/tools/mod.rs
+++ b/crates/kebab-mcp/src/tools/mod.rs
@@ -4,3 +4,5 @@ pub mod schema;
 pub mod doctor;
 pub mod search;
 pub mod ask;
+pub mod ingest_file;
+pub mod ingest_stdin;
diff --git a/crates/kebab-mcp/tests/tools_call_ingest_file.rs b/crates/kebab-mcp/tests/tools_call_ingest_file.rs
new file mode 100644
index 0000000..ff112b8
--- /dev/null
+++ b/crates/kebab-mcp/tests/tools_call_ingest_file.rs
@@ -0,0 +1,117 @@
+//! Integration: tools/call name=ingest_file → ingest_report.v1.
+
+use std::fs;
+
+use kebab_config::Config;
+use kebab_mcp::{KebabAppState, KebabHandler};
+use rmcp::model::RawContent;
+
+#[tokio::test]
+async fn ingest_file_tool_returns_ingest_report_v1() {
+    let dir = tempfile::tempdir().unwrap();
+    let workspace = dir.path().join("notes");
+    let data = dir.path().join("data");
+    fs::create_dir_all(&workspace).unwrap();
+    fs::create_dir_all(&data).unwrap();
+
+    let mut cfg = Config::defaults();
+    cfg.workspace.root = workspace.to_string_lossy().into_owned();
+    cfg.storage.data_dir = data.to_string_lossy().into_owned();
+    cfg.models.embedding.provider = "none".to_string();
+    cfg.models.embedding.dimensions = 0;
+
+    let src = dir.path().join("doc.md");
+    fs::write(&src, "# Title\n\nbody.").unwrap();
+
+    let state = KebabAppState::new(cfg, None);
+    let handler = KebabHandler::new(state);
+
+    let result = tokio::task::spawn_blocking({
+        let state = handler.state().clone();
+        let path = src.to_string_lossy().into_owned();
+        move || {
+            kebab_mcp::tools::ingest_file::handle(
+                &state,
+                kebab_mcp::tools::ingest_file::IngestFileInput { path },
+            )
+        }
+    })
+    .await
+    .unwrap();
+
+    assert!(!result.is_error.unwrap_or(false), "{result:?}");
+    let text = match &result.content.first().unwrap().raw {
+        RawContent::Text(t) => &t.text,
+        other => panic!("expected text content, got {other:?}"),
+    };
+    let v: serde_json::Value = serde_json::from_str(text).unwrap();
+    assert_eq!(
+        v.get("schema_version").and_then(|s| s.as_str()),
+        Some("ingest_report.v1")
+    );
+    assert_eq!(v.get("new").and_then(|n| n.as_u64()), Some(1));
+}
+
+#[tokio::test]
+async fn ingest_file_tool_idempotent_on_second_call() {
+    let dir = tempfile::tempdir().unwrap();
+    let workspace = dir.path().join("notes");
+    let data = dir.path().join("data");
+    std::fs::create_dir_all(&workspace).unwrap();
+    std::fs::create_dir_all(&data).unwrap();
+
+    let mut cfg = kebab_config::Config::defaults();
+    cfg.workspace.root = workspace.to_string_lossy().into_owned();
+    cfg.storage.data_dir = data.to_string_lossy().into_owned();
+    cfg.models.embedding.provider = "none".to_string();
+    cfg.models.embedding.dimensions = 0;
+
+    let src = dir.path().join("doc.md");
+    std::fs::write(&src, "# A\n\nbody.").unwrap();
+
+    let state = kebab_mcp::KebabAppState::new(cfg, None);
+    let handler = kebab_mcp::KebabHandler::new(state);
+
+    // First call.
+    let r1 = tokio::task::spawn_blocking({
+        let state = handler.state().clone();
+        let path = src.to_string_lossy().into_owned();
+        move || {
+            kebab_mcp::tools::ingest_file::handle(
+                &state,
+                kebab_mcp::tools::ingest_file::IngestFileInput { path },
+            )
+        }
+    })
+    .await
+    .unwrap();
+    assert!(!r1.is_error.unwrap_or(false));
+    let text1 = match &r1.content.first().unwrap().raw {
+        rmcp::model::RawContent::Text(t) => &t.text,
+        other => panic!("expected text, got {other:?}"),
+    };
+    let v1: serde_json::Value = serde_json::from_str(text1).unwrap();
+    assert_eq!(v1.get("new").and_then(|n| n.as_u64()), Some(1));
+
+    // Second call — same content, expect unchanged=1.
+    let r2 = tokio::task::spawn_blocking({
+        let state = handler.state().clone();
+        let path = src.to_string_lossy().into_owned();
+        move || {
+            kebab_mcp::tools::ingest_file::handle(
+                &state,
+                kebab_mcp::tools::ingest_file::IngestFileInput { path },
+            )
+        }
+    })
+    .await
+    .unwrap();
+    assert!(!r2.is_error.unwrap_or(false));
+    let text2 = match &r2.content.first().unwrap().raw {
+        rmcp::model::RawContent::Text(t) => &t.text,
+        other => panic!("expected text, got {other:?}"),
+    };
+    let v2: serde_json::Value = serde_json::from_str(text2).unwrap();
+    assert_eq!(v2.get("new").and_then(|n| n.as_u64()), Some(0), "{v2:?}");
+    assert_eq!(v2.get("unchanged").and_then(|n| n.as_u64()), Some(1), "{v2:?}");
+}
diff --git a/crates/kebab-mcp/tests/tools_call_ingest_stdin.rs b/crates/kebab-mcp/tests/tools_call_ingest_stdin.rs
new file mode 100644
index 0000000..45943d6
--- /dev/null
+++ b/crates/kebab-mcp/tests/tools_call_ingest_stdin.rs
@@ -0,0 +1,89 @@
+//! Integration: tools/call name=ingest_stdin → ingest_report.v1.
+//! Frontmatter precheck path also covered.
+
+use std::fs;
+
+use kebab_config::Config;
+use kebab_mcp::KebabAppState;
+use rmcp::model::RawContent;
+
+fn fresh_state(dir: &std::path::Path) -> KebabAppState {
+    let workspace = dir.join("notes");
+    let data = dir.join("data");
+    fs::create_dir_all(&workspace).unwrap();
+    fs::create_dir_all(&data).unwrap();
+
+    let mut cfg = Config::defaults();
+    cfg.workspace.root = workspace.to_string_lossy().into_owned();
+    cfg.storage.data_dir = data.to_string_lossy().into_owned();
+    cfg.models.embedding.provider = "none".to_string();
+    cfg.models.embedding.dimensions = 0;
+    KebabAppState::new(cfg, None)
+}
+
+#[tokio::test]
+async fn ingest_stdin_tool_returns_ingest_report_v1() {
+    let dir = tempfile::tempdir().unwrap();
+    let state = fresh_state(dir.path());
+
+    let result = tokio::task::spawn_blocking({
+        let state = state.clone();
+        move || {
+            kebab_mcp::tools::ingest_stdin::handle(
+                &state,
+                kebab_mcp::tools::ingest_stdin::IngestStdinInput {
+                    content: "## Body".to_string(),
+                    title: "X".to_string(),
+                    source_uri: Some("https://example.com/x".to_string()),
+                },
+            )
+        }
+    })
+    .await
+    .unwrap();
+
+    assert!(!result.is_error.unwrap_or(false), "{result:?}");
+    let text = match &result.content.first().unwrap().raw {
+        RawContent::Text(t) => &t.text,
+        other => panic!("expected text content, got {other:?}"),
+    };
+    let v: serde_json::Value = serde_json::from_str(text).unwrap();
+    assert_eq!(
+        v.get("schema_version").and_then(|s| s.as_str()),
+        Some("ingest_report.v1")
+    );
+    assert_eq!(v.get("new").and_then(|n| n.as_u64()), Some(1));
+}
+
+#[tokio::test]
+async fn ingest_stdin_tool_emits_error_v1_on_existing_frontmatter() {
+    let dir = tempfile::tempdir().unwrap();
+    let state = fresh_state(dir.path());
+
+    let result = tokio::task::spawn_blocking({
+        let state = state.clone();
+        move || {
+            kebab_mcp::tools::ingest_stdin::handle(
+                &state,
+                kebab_mcp::tools::ingest_stdin::IngestStdinInput {
+                    content: "---\ntitle: Existing\n---\n\n## Body".to_string(),
+                    title: "New".to_string(),
+                    source_uri: None,
+                },
+            )
+        }
+    })
+    .await
+    .unwrap();
+
+    assert_eq!(result.is_error, Some(true), "{result:?}");
+    let text = match &result.content.first().unwrap().raw {
+        RawContent::Text(t) => &t.text,
+        other => panic!("expected text content, got {other:?}"),
+    };
+    let v: serde_json::Value = serde_json::from_str(text).unwrap();
+    assert_eq!(
+        v.get("schema_version").and_then(|s| s.as_str()),
+        Some("error.v1")
+    );
+}
diff --git a/crates/kebab-mcp/tests/tools_list.rs b/crates/kebab-mcp/tests/tools_list.rs
index f7c0cd4..01bfe6e 100644
--- a/crates/kebab-mcp/tests/tools_list.rs
+++ b/crates/kebab-mcp/tests/tools_list.rs
@@ -1,19 +1,21 @@
-//! Integration: `build_tools_vec` returns 4 tools with correct names and
+//! Integration: `build_tools_vec` returns 6 tools with correct names and
 //! inputSchema. Uses the extracted `pub fn build_tools_vec()` helper — no
 //! transport or RequestContext needed.
 
 use kebab_mcp::build_tools_vec;
 
 #[test]
-fn tools_list_returns_four_tools() {
+fn tools_list_returns_six_tools() {
     let tools = build_tools_vec();
-    assert_eq!(tools.len(), 4, "expected exactly 4 tools, got {}", tools.len());
+    assert_eq!(tools.len(), 6, "expected exactly 6 tools, got {}", tools.len());
 
     let names: Vec<&str> = tools.iter().map(|t| t.name.as_ref()).collect();
     assert!(names.contains(&"schema"), "missing 'schema' tool");
     assert!(names.contains(&"doctor"), "missing 'doctor' tool");
     assert!(names.contains(&"search"), "missing 'search' tool");
     assert!(names.contains(&"ask"), "missing 'ask' tool");
+    assert!(names.contains(&"ingest_file"), "missing 'ingest_file' tool");
+    assert!(names.contains(&"ingest_stdin"), "missing 'ingest_stdin' tool");
 }
 
 #[test]
diff --git a/docs/mcp-usage.md b/docs/mcp-usage.md
new file mode 100644
index 0000000..7f3aa85
--- /dev/null
+++ b/docs/mcp-usage.md
@@ -0,0 +1,486 @@
+# MCP usage — agent integration guide
+
+`kebab mcp` runs an MCP (Model Context Protocol) stdio JSON-RPC server. agent host (Claude Code / Cursor / OpenAI Agents / Copilot CLI 등) 가 본 binary 를 spawn 하여 KB 검색 / 답변 / ingest 를 호출.
+
+shipped since **v0.3.1** (fb-30). 6 tool 으로 확장 (v0.3.2, fb-31).
+
+---
+
+## Quick start
+
+binary 를 PATH 에 두고 (`cargo install --path crates/kebab-cli` 또는 release tarball), agent host 의 mcp config 에 등록:
+
+```json
+{
+  "mcpServers": {
+    "kebab": {
+      "command": "kebab",
+      "args": ["mcp"]
+    }
+  }
+}
+```
+
+session 시작 시 host 가 `kebab mcp` 를 spawn — process 가 session 동안 살아 있어 SQLite / Lance / fastembed 가 hot. 첫 tool call 만 cold-start 비용, 이후 sub-100ms.
+
+`--config` 옵션 thread:
+
+```json
+{
+  "mcpServers": {
+    "kebab": {
+      "command": "kebab",
+      "args": ["--config", "/Users/me/.config/kebab/agent.toml", "mcp"]
+    }
+  }
+}
+```
+
+---
+
+## Host config 예시
+
+### Claude Code
+
+`~/.claude/mcp.json` (또는 OS 별 동등 위치):
+
+```json
+{
+  "mcpServers": {
+    "kebab": {
+      "command": "kebab",
+      "args": ["mcp"]
+    }
+  }
+}
+```
+
+session 재시작 후 `kebab` server 가 tool list 에 등장. agent 가 `mcp__kebab__search` / `mcp__kebab__ask` 등 호출 가능.
+
+### Cursor
+
+`~/.cursor/mcp.json`:
+
+```json
+{
+  "mcpServers": {
+    "kebab": {
+      "command": "kebab",
+      "args": ["mcp"]
+    }
+  }
+}
+```
+
+Cursor 의 Composer / Agent 모드에서 활성화.
+
+### OpenAI Agents (`agents-sdk`)
+
+Python:
+
+```python
+from openai_agents import Agent, MCPServerStdio
+
+kebab = MCPServerStdio(
+    name="kebab",
+    params={"command": "kebab", "args": ["mcp"]},
+)
+
+agent = Agent(
+    name="researcher",
+    mcp_servers=[kebab],
+)
+```
+
+Node:
+
+```ts
+import { Agent, MCPServerStdio } from "openai-agents";
+
+const kebab = new MCPServerStdio({
+  name: "kebab",
+  params: { command: "kebab", args: ["mcp"] },
+});
+
+const agent = new Agent({ name: "researcher", mcpServers: [kebab] });
+```
+
+### Copilot CLI
+
+`~/.config/copilot-cli/mcp.json` (or wherever the CLI looks):
+
+```json
+{
+  "mcpServers": {
+    "kebab": {
+      "command": "kebab",
+      "args": ["mcp"]
+    }
+  }
+}
+```
+
+### 기타 host
+
+stdio JSON-RPC MCP 표준을 따르는 모든 host 가 지원. 위 형식 (`command` + `args`) 만 맞추면 동작.
+
+---
+
+## Tool catalog (6 tools)
+
+모든 tool 의 출력은 wire schema v1 JSON 을 MCP `text` content block 으로 직렬화. CLI `--json` 모드와 byte-동일 (single source of truth).
+
+### `search` — corpus 검색
+
+| | |
+|---|---|
+| Input | `{ "query": string, "mode"?: "lexical"\|"vector"\|"hybrid", "k"?: 1-100 }` |
+| Defaults | `mode = "hybrid"`, `k = 10` |
+| Output | `search_hit.v1` array, ranked |
+
+예시:
+
+```json
+{
+  "name": "search",
+  "arguments": {
+    "query": "Kubernetes ingress controller setup",
+    "mode": "hybrid",
+    "k": 5
+  }
+}
+```
+
+응답 (한 hit 발췌):
+
+```json
+[
+  {
+    "schema_version": "search_hit.v1",
+    "rank": 1,
+    "score": 0.847,
+    "doc_id": "...",
+    "chunk_id": "...",
+    "doc_path": "k8s/ingress.md",
+    "heading_path": ["Setup", "Ingress controller"],
+    "snippet": "...",
+    "citation": { ... }
+  },
+  ...
+]
+```
+
+**언제 사용**: 사용자가 \"문서 어디 있는지\" 묻거나, agent 가 답변 전 raw chunk 가 필요할 때.
+
+### `ask` — RAG 답변
+
+| | |
+|---|---|
+| Input | `{ "query": string, "session_id"?: string, "mode"?: "lexical"\|"vector"\|"hybrid" }` |
+| Defaults | `mode = "hybrid"` |
+| Output | `answer.v1` (single object) |
+
+예시:
+
+```json
+{
+  "name": "ask",
+  "arguments": {
+    "query": "What's our internal Kubernetes ingress setup?",
+    "session_id": "ops-onboarding-2026-05"
+  }
+}
+```
+
+응답:
+
+```json
+{
+  "schema_version": "answer.v1",
+  "answer": "...",
+  "citations": [ ... ],
+  "grounded": true,
+  "refusal_reason": null,
+  "model": { ... },
+  "conversation_id": "...",
+  "turn_index": 0
+}
+```
+
+**`grounded: false` 처리**: KB 에 충분한 context 없음. `refusal_reason` 확인 후 사용자에게 \"KB 에 정보 없음\" 으로 안내, 본인 지식 fallback 또는 source 요청. **paraphrase 하면 안 됨** (hallucination 위험).
+
+multi-turn 은 [Session 관리](#session-관리-multi-turn-ask) 참조.
+
+### `schema` — capability discovery
+
+| | |
+|---|---|
+| Input | `{}` (no args) |
+| Output | `schema.v1` |
+
+예시:
+
+```json
+{ "name": "schema", "arguments": {} }
+```
+
+응답:
+
+```json
+{
+  "schema_version": "schema.v1",
+  "kebab_version": "0.3.2",
+  "wire": { "schemas": ["answer.v1", "search_hit.v1", ...] },
+  "capabilities": {
+    "json_mode": true,
+    "rag_multi_turn": true,
+    "mcp_server": true,
+    "streaming_ask": false,
+    ...
+  },
+  "models": { "parser_version": "...", "embedding_version": "...", ... },
+  "stats": { "doc_count": 128, "chunk_count": 2147, "asset_count": 130, ... }
+}
+```
+
+**언제 사용**: session 시작 시 한 번 — feature gate 결정 (`capabilities.streaming_ask` true 면 streaming 사용 등). cheap call (no LLM, no embedder), session 동안 1 회 충분.
+
+### `doctor` — health check
+
+| | |
+|---|---|
+| Input | `{}` (no args) |
+| Output | `doctor.v1` |
+
+예시:
+
+```json
+{ "name": "doctor", "arguments": {} }
+```
+
+응답:
+
+```json
+{
+  "schema_version": "doctor.v1",
+  "ok": true,
+  "checks": [
+    { "name": "config_loaded", "ok": true, "detail": "..." },
+    { "name": "ollama_reachable", "ok": true, "detail": "..." },
+    ...
+  ]
+}
+```
+
+**언제 사용**: 다른 tool 이 실패하거나 비정상 응답 줄 때 first triage. `ok: false` 면 `checks[]` 의 failed entry 가 원인 — 사용자에게 보고 후 stop (자동 retry 금지).
+
+### `ingest_file` — 단일 파일 저장 (mutation)
+
+| | |
+|---|---|
+| Input | `{ "path": string }` |
+| Supported ext | `.md` / `.pdf` / `.png` / `.jpg` / `.jpeg` (`unsupported extension` error 그 외) |
+| Output | `ingest_report.v1` (single asset) |
+
+예시:
+
+```json
+{
+  "name": "ingest_file",
+  "arguments": { "path": "/Users/me/Downloads/article.md" }
+}
+```
+
+응답:
+
+```json
+{
+  "schema_version": "ingest_report.v1",
+  "scanned": 1,
+  "new": 1,
+  "updated": 0,
+  "unchanged": 0,
+  "skipped": 0,
+  "errors": 0,
+  ...
+}
+```
+
+**언제 사용**: 사용자가 disk 의 file 을 KB 에 저장 의향 명시 시. workspace 외부 path OK — 파일은 `<workspace.root>/_external/<hash12>.<ext>` 으로 copy. 동일 content 재 ingest 면 idempotent (`unchanged: 1`).
+
+**주의**: mutation tool — 사용자 명시 의도 없을 때 자동 호출 금지.
+
+### `ingest_stdin` — stdin markdown 저장 (mutation)
+
+| | |
+|---|---|
+| Input | `{ "content": string, "title": string, "source_uri"?: string }` |
+| v1 scope | markdown only |
+| Output | `ingest_report.v1` (single asset) |
+
+예시:
+
+```json
+{
+  "name": "ingest_stdin",
+  "arguments": {
+    "content": "## Article body\n\nMain text here.",
+    "title": "Article X",
+    "source_uri": "https://example.com/x"
+  }
+}
+```
+
+응답:
+
+```json
+{
+  "schema_version": "ingest_report.v1",
+  "scanned": 1,
+  "new": 1,
+  ...
+}
+```
+
+**언제 사용**: agent 가 web fetch 한 markdown article 을 KB 에 저장. 사용자가 \"이거 나중에 또 보고 싶어\" 명시 시 또는 multi-turn 대화에서 자료 누적. content 가 이미 frontmatter (`---` 시작) 이면 error — `ingest_file` 사용.
+
+`title` + `source_uri` 가 frontmatter 로 자동 prepend → `Document.metadata` 에 저장 → 후속 `search` 결과의 `doc_meta` 에 포함. agent 가 source URL 추적 가능.
+
+**주의**: mutation tool. 같은 content 무한 ingest 안 함 (idempotent 보장이지만 embedding cost 낭비).
+
+---
+
+## Troubleshooting
+
+### `isError: true` + `error.v1` content
+
+tool dispatch 가 `Err` 반환 시. content 의 `error.v1` JSON 의 `code` 로 분기:
+
+| code | 의미 | 조치 |
+|------|------|------|
+| `config_invalid` | `--config` path missing / TOML parse 실패 | path 확인 + `kebab schema` 로 검증. `details.path` + `details.cause` 확인. |
+| `not_indexed` | `kebab.sqlite` 미존재 / migration 미실행 | 사용자에게 `kebab init` + `kebab ingest` 실행 안내. retry 자동 금지. |
+| `model_unreachable` | Ollama endpoint 연결 실패 | Ollama 실행 확인 (`ollama serve`). `details.endpoint` 의 host 가 reachable 한지. retry 1-2 회 후 사용자 보고. |
+| `model_not_pulled` | Ollama model not found | 사용자에게 `ollama pull <model>` 안내 — `details.model` 표시. |
+| `timeout` | LLM stream / embed deadline 초과 | 일시적이면 retry 1 회. 재발 시 사용자 보고 (model 응답 느림 / Ollama load). |
+| `io_error` | filesystem / 권한 / disk full | `details.kind` 보고 사용자에게 disk space / permission 확인 안내. |
+| `generic` | catch-all | `details.chain` (verbose 시) 보고 사용자에게 그대로 전달. retry 금지. |
+
+`hint` field 가 있으면 사용자에게 그대로 보여주기 (각 code 의 가장 빠른 조치).
+
+### `grounded: false` (ask refusal)
+
+`isError: false` (정상 응답). KB 에 충분한 context 없음. `refusal_reason` 확인 후:
+
+- `NoChunks` — 검색 자체가 0 hit. 다른 표현 / 더 일반적인 query 시도.
+- `LowScores` — hit 있지만 score gate 미달. `kebab search` (별도) 로 raw hit 확인.
+- 그 외 — refusal 메시지 그대로 사용자에게 보고.
+
+자동 paraphrase 금지. 사용자에게 \"KB 에 정보 없음\" 명시 후 본인 지식 또는 source 요청.
+
+### `doctor` `ok: false`
+
+다른 tool 호출 전 `doctor` 부터. `checks[]` 의 failed entry 원인 명시 — 사용자에게 보고 후 stop.
+
+### empty `search` result
+
+`isError: false`, content = `[]` (빈 array). KB 에 매칭 없음. `mode` 변경 (lexical → vector or vice versa) 또는 query 표현 다양화. 그래도 빈 결과면 KB coverage 부족 — 사용자에게 보고.
+
+### tool not found
+
+`tools/list` 에서 본 binary 의 6 tool 확인. 0.3.1 (fb-30) 은 4 tool, 0.3.2 (fb-31) 부터 6. binary version 확인:
+
+```json
+{ "name": "schema", "arguments": {} }
+```
+
+응답의 `kebab_version` 이 0.3.2+ 인지 확인.
+
+---
+
+## Session 관리 (multi-turn ask)
+
+`ask` tool 의 `session_id` 가 multi-turn RAG context 활성화. 같은 `session_id` 로 연속 호출 시 이전 Q/A history 가 새 query 의 retrieval expansion + prompt context 에 포함.
+
+### session_id 명명
+
+`<topic>-<date>` 형식 권장 — 사용자 친화 + uniqueness:
+
+- `ops-onboarding-2026-05`
+- `kubernetes-ingress-debug-2026-05-07`
+- `agent-research-session-1` (auto-numbered)
+
+session_id 는 임의 string — kebab 이 처음 보는 id 면 새 session 생성, 기존 id 면 history append.
+
+### 언제 새 session 시작?
+
+- 주제 완전 전환 (KB 의 다른 도메인) — 이전 history 가 noise.
+- 사용자 명시 reset 요청.
+- Long session (50+ turn) 의 context bloat — 새 session 으로 fresh start.
+
+### Session lifetime
+
+session 데이터는 SQLite `chat_sessions` + `chat_turns` 에 영속. `kebab reset --data-only` 가 모두 wipe. session 별 삭제 명령은 없음 (P+).
+
+### 예시 multi-turn flow
+
+```json
+// turn 1
+{ "name": "ask", "arguments": {
+  "query": "What's our internal Kubernetes ingress setup?",
+  "session_id": "ops-2026-05"
+}}
+// → answer.v1 with conversation_id, turn_index: 0
+
+// turn 2 — 이전 답변을 context 로 retrieval expansion
+{ "name": "ask", "arguments": {
+  "query": "What about TLS?",
+  "session_id": "ops-2026-05"
+}}
+// → kebab 가 "TLS" 만으로 retrieval 안 함, 이전 \"Kubernetes ingress\" history 포함 query 로 검색
+
+// turn 3 — 명시적 reference
+{ "name": "ask", "arguments": {
+  "query": "How does that compare to AWS ALB?",
+  "session_id": "ops-2026-05"
+}}
+```
+
+### Session vs single-shot
+
+`session_id` 없이 `ask` 호출 = single-shot. agent host 자체가 conversation 추적하면 single-shot + agent-side context 도 OK. session 이 필요한 경우:
+
+- KB 가 \"이전 질문\" 을 retrieval expansion 에 사용해야 정확 (e.g. follow-up 의 대명사).
+- 한 session 안에서 같은 chunk 반복 fetch 회피 (kebab 가 turn 간 chunk overlap 인지).
+
+agent host 가 conversation 추적 + 충분한 context 보유면 session 불필요.
+
+---
+
+## Performance
+
+- **첫 tool call**: cold start ~1-2s (SQLite open + Lance dataset open + fastembed model load).
+- **이후 tool call (same session)**: hot — search ~50-200ms, ask ~수 초 (Ollama LLM dominant).
+- **session 종료** (host 가 process kill): 모든 cache lost. 다음 session 첫 call 다시 cold.
+- **`schema` / `doctor`**: cheap (no LLM / no embedder), 매 call ~ms.
+- **`ingest_file` / `ingest_stdin`**: 첫 call 시 fastembed cold start. 이후 file 당 ~수 백 ms (parse + chunk + embed).
+
+cold-start 회피하려면 host 가 long-running session 유지 (Claude Code default).
+
+---
+
+## Security
+
+- stdio MCP — 외부 네트워크 노출 없음. agent host 만 access.
+- `kebab mcp` 가 호출하는 facade 는 `--config` 의 권한으로 동작. config 내 secret (Ollama API key 등) 은 process 환경에 한정.
+- mutation tool (`ingest_file` / `ingest_stdin`) 는 사용자 명시 의도 없이 자동 호출 금지 — agent 측 가드.
+
+---
+
+## Related
+
+- CLI usage: `kebab --help` + [README.md](../README.md)
+- Wire schemas: `docs/wire-schema/v1/*.schema.json`
+- design contract: `docs/superpowers/specs/2026-04-27-kebab-final-form-design.md` §10.2
+- Claude Code 전용 skill: `integrations/claude-code/kebab/SKILL.md`
+- HOTFIXES (post-merge deviations): `tasks/HOTFIXES.md`
diff --git a/docs/superpowers/specs/2026-04-27-kebab-final-form-design.md b/docs/superpowers/specs/2026-04-27-kebab-final-form-design.md
index ad2f9fd..5f5835f 100644
--- a/docs/superpowers/specs/2026-04-27-kebab-final-form-design.md
+++ b/docs/superpowers/specs/2026-04-27-kebab-final-form-design.md
@@ -1206,6 +1206,12 @@ hint     edit ~/.config/kebab/config.toml then `kebab ingest ~/KnowledgeBase`
 - 항상 POSIX path 정규화 후 DB 저장. `to_posix` 단일 함수.
 - 심볼릭 링크: 1차 follow + 무한루프 detect (`canonicalize` 후 set 추적).
 
+### 6.7 `_external/` subdirectory (fb-31)
+
+`<workspace.root>/_external/` 가 single-file / stdin ingest 의 destination. 명명: `<blake3-12>.<ext>` (12-char hex prefix of content hash + 원래 extension). deterministic — 동일 content 재 ingest 면 idempotent.
+
+첫 생성 시 `<workspace.root>/.kebabignore` 에 `_external/` line 자동 append — 향후 `kebab ingest` 전체 walk 가 이 디렉토리 재 walk 안 함 (re-ingestion 무한 루프 방지).
+
 ---
 
 ## 7. Trait contracts (kebab-core)
diff --git a/integrations/claude-code/kebab/SKILL.md b/integrations/claude-code/kebab/SKILL.md
index 2f74cda..6f757e1 100644
--- a/integrations/claude-code/kebab/SKILL.md
+++ b/integrations/claude-code/kebab/SKILL.md
@@ -73,7 +73,7 @@ If a call fails or returns suspicious output, run `kebab doctor` first — it su
 
 ## MCP server (recommended over CLI subprocess wrapping)
 
-Since v0.4.0, `kebab` exposes an MCP (Model Context Protocol) stdio server. Configure once in `~/.claude/mcp.json`:
+Since v0.3.1, `kebab` exposes an MCP (Model Context Protocol) stdio server. Configure once in `~/.claude/mcp.json`:
 
 ```json
 {
@@ -86,10 +86,27 @@ Since v0.4.0, `kebab` exposes an MCP (Model Context Protocol) stdio server. Conf
 }
 ```
 
-Claude Code spawns `kebab mcp` at session start; the process stays alive across all tool calls so SQLite / Lance / fastembed are hot after the first call. 4 tools available: `search` / `ask` / `schema` / `doctor`. Same wire shapes as the CLI `--json` mode — see `Two surfaces, pick the right one` above for the same guidance.
+Claude Code spawns `kebab mcp` at session start; the process stays alive across all tool calls so SQLite / Lance / fastembed are hot after the first call. 6 tools available: `search` / `ask` / `schema` / `doctor` / `ingest_file` / `ingest_stdin`. Same wire shapes as the CLI `--json` mode — see `Two surfaces, pick the right one` above for the same guidance.
 
 If your host doesn't support MCP, the CLI subprocess pattern (`kebab search --json` / `kebab ask --json`) above continues to work.
 
+For per-tool input/output examples, error code reference, multi-turn ask + session management, and host config beyond Claude Code (Cursor / OpenAI Agents / Copilot CLI), see [docs/mcp-usage.md](../../../docs/mcp-usage.md) in the kebab repo.
+
+## Recipe D — agent fetched a web doc, save to KB
+
+When you've fetched a markdown article (e.g. via WebFetch) that the user might query later:
+
+1. Call MCP tool `ingest_stdin` with:
+   - `content`: the markdown body
+   - `title`: a stable title (article H1 or page title)
+   - `source_uri`: the URL you fetched from
+
+The doc lands in `<workspace.root>/_external/<hash>.md` and is indexed for `search` / `ask` immediately. Subsequent calls with identical content are no-ops (incremental ingest detects unchanged hash).
+
+Don't loop ingest the same article — content-hash dedup makes it safe but wastes embedding cost.
+
+For files already on disk that the user references, prefer `ingest_file` with the path — kebab handles the copy + dedup.
+
 ## Workflow recipes
 
 **Recipe A — user asks an internal-context question, you want grounded answer:**
diff --git a/tasks/HOTFIXES.md b/tasks/HOTFIXES.md
index 6dc93e2..ecd605a 100644
--- a/tasks/HOTFIXES.md
+++ b/tasks/HOTFIXES.md
@@ -14,6 +14,39 @@ historical contract that was implemented; this file accumulates the
 deltas so phase 5+ readers can find the live behavior without diffing
 git history.
 
+## 2026-05-07 — p9-fb-31 (post-dogfooding): single-file / stdin ingest
+
+**Source feedback**: 사용자 도그푸딩 2026-05-06 — agent (Claude Code via MCP, fb-30) 가 web fetch 한 markdown / 단일 외부 file 을 KB 에 저장하려면 `kebab ingest` 전체 walk 재실행 비효율. agent 메모리상 string contents 도 stdin ingest 가능해야.
+
+**Live binding 변경**:
+
+- 신규 subcommand `kebab ingest-file <path>` — 단일 file ingest, workspace 외부 path 가능.
+- 신규 subcommand `kebab ingest-stdin --title <T> [--source-uri <URI>]` — stdin 의 markdown 본문 ingest, v1 markdown only.
+- 신규 MCP tool `ingest_file` + `ingest_stdin` — fb-30 v1 read-only 정책 변경, 첫 mutation surface 도입 (의도된 진화). tools/list 4 → 6.
+- 외부 file 저장 정책: `<workspace.root>/_external/<blake3-12>.<ext>` 로 copy. deterministic 명명 → idempotent. `_external/` 첫 생성 시 `.kebabignore` 자동 append (walk 무한 루프 방지).
+- `.kebabignore` 매치 시 stderr warn (`warn: <path> matches .kebabignore patterns; proceeding (explicit ingest bypasses ignore)`) 후 진행. `--force-ignore` flag 불필요 — explicit ingest 가 default bypass intent.
+- stdin frontmatter 처리: 본문이 `---` 으로 시작하면 error (`use kebab ingest-file`); 그 외 frontmatter block prepend (title + 옵션 source_uri, YAML 더블쿼트 escape).
+- `kebab-app::external` 신규 모듈 — `ensure_external_dir`, `ensure_kebabignore_entry`, `copy_to_external`, `inject_frontmatter` helper. kebab-cli + kebab-mcp 둘 다 facade 통해 호출.
+- `kebab-app::ingest_file_with_config` + `ingest_stdin_with_config` 신규 facade fn.
+
+**Spec contract impact**: design §6 에 `_external/` subdirectory 절 추가 (실제 §6.7 — 기존 §6 sub-section 이 6.6 까지 채워져 있어 §6.7 로 부착됨; spec stub 의 §6.3 명시는 deviation).
+
+**Tests added**: kebab-app external::tests (14: dir / kebabignore append / copy / inject_frontmatter / yaml_quote), kebab-app integration (3 + 3: ingest_file + ingest_stdin), kebab-cli integration (2: cli_ingest_file + cli_ingest_stdin spawn-based), kebab-mcp integration (1 + 2: tools_call_ingest_file + tools_call_ingest_stdin), tools_list assertion update (4 → 6).
+
+**Known limitation (deferred)**:
+
+- PDF / image stdin — binary stream + base64 처리 v2.
+- `--title` + `--source-uri` 외 metadata field (tags, language, custom kv) — v2.
+- 자동 dedup by source_uri — content hash 기반 dedup 만 (incremental ingest). URI lookup 별 task.
+- Storage quota / TTL — agent 무한 ingest 시 KB 비대 우려. monitor + 별 task.
+- frontmatter merge (stdin 이 이미 frontmatter 보유 시 머지) — v1 은 error.
+- MCP `ingest_file` 의 multi-file batch 입력 — v1 single path. 여러 file 호출은 agent 가 N 회.
+
+**Amends**:
+- design §6 (`_external/` subdirectory subsection 추가, §6.7 위치).
+- spec `tasks/p9/p9-fb-31-single-file-stdin-ingest.md` (status `open` → `completed`).
+- spec stub 의 §6.3 명시 → 실제 §6.7 (기존 §6 구조 우선).
+
 ## 2026-05-07 — p9-fb-30 (post-dogfooding): MCP server (stdio) — agent integration MVP
 
 **Source feedback**: 사용자 도그푸딩 2026-05-06 — Claude Code 같은 AI agent 가 kebab CLI 를 사용하는 것이 궁극 목표. 현재 surface 는 Claude Code 전용 skill (subprocess wrapper) 만 — host 무관 표준 통신 없음. fb-29 HTTP daemon 은 single-user local-first 환경 대비 비대로 deferred (2026-05-07), fb-30 stdio MCP 가 동일 사용자 가치 (agent integration + session 동안 hot cache) 를 daemon 복잡도 없이 제공.
diff --git a/tasks/p9/p9-fb-31-single-file-stdin-ingest.md b/tasks/p9/p9-fb-31-single-file-stdin-ingest.md
index 74026eb..5f1ed8d 100644
--- a/tasks/p9/p9-fb-31-single-file-stdin-ingest.md
+++ b/tasks/p9/p9-fb-31-single-file-stdin-ingest.md
@@ -3,7 +3,7 @@ phase: P9
 component: kebab-cli + kebab-app
 task_id: p9-fb-31
 title: "Single-file / stdin ingest — agent on-demand 저장"
-status: open
+status: completed
 target_version: 0.3.0
 depends_on: []
 unblocks: []
@@ -14,7 +14,7 @@ source_feedback: 사용자 도그푸딩 2026-05-06 — agent 가 읽은 article
 
 # p9-fb-31 — Single-file / stdin ingest
 
-> ⏳ **백로그 only — 미구현.** 본 spec 은 도그푸딩 피드백 skeleton. 구현 착수 전 [superpowers:brainstorming](../../docs/superpowers/) 으로 설계 단계 선행 필요. workspace 외부 file 의 저장 위치 / metadata 입력 방식 / .kebabignore 우회 정책 brainstorm 후 확정.
+> ✅ **구현 완료.** 본 spec 은 구현 시점의 frozen 상태. post-merge deviation 은 [HOTFIXES.md](../HOTFIXES.md) 의 `2026-05-07 — p9-fb-31` 항목 참조 — live source of truth.
 
 ## 증상 / 동기