diff --git a/Cargo.lock b/Cargo.lock
index f677cf3..60cbf2e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3360,6 +3360,7 @@ dependencies = [
  "usearch",
  "uuid",
  "walkdir",
+ "which",
  "zip",
 ]
 
@@ -4522,6 +4523,15 @@ dependencies = [
  "rustls-pki-types",
 ]
 
+[[package]]
+name = "which"
+version = "8.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "81995fafaaaf6ae47a7d0cc83c67caf92aeb7e5331650ae6ff856f7c0c60c459"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "winapi"
 version = "0.3.9"
diff --git a/Cargo.toml b/Cargo.toml
index 21a13a6..5fdcdec 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -40,6 +40,7 @@ async-trait = "0.1"
 ort = { version = "=2.0.0-rc.10", features = ["load-dynamic", "ndarray"] }
 ndarray = "0.16"
 tokenizers = { version = "0.21", default-features = false, features = ["fancy-regex"] }
+which = "8"
 kiwi-rs = "0.1"
 sha2 = "0.10"
 tracing = "0.1"
diff --git a/crates/secall-core/Cargo.toml b/crates/secall-core/Cargo.toml
index fdd72e8..d6c8cd0 100644
--- a/crates/secall-core/Cargo.toml
+++ b/crates/secall-core/Cargo.toml
@@ -23,6 +23,7 @@ async-trait.workspace = true
 ort.workspace = true
 ndarray.workspace = true
 tokenizers.workspace = true
+which.workspace = true
 sha2.workspace = true
 regex.workspace = true
 futures-util.workspace = true
diff --git a/crates/secall-core/src/lib.rs b/crates/secall-core/src/lib.rs
index 9551bb3..8a9cf97 100644
--- a/crates/secall-core/src/lib.rs
+++ b/crates/secall-core/src/lib.rs
@@ -24,27 +24,27 @@ pub async fn http_post_json(url: &str, body: &serde_json::Value) -> anyhow::Resu
     Ok(())
 }
 
-/// 크로스플랫폼 명령어 존재 확인
-pub fn command_exists(cmd: &str) -> bool {
-    #[cfg(target_os = "windows")]
-    let check = std::process::Command::new("where.exe")
-        .arg(cmd)
-        .stdout(std::process::Stdio::null())
-        .stderr(std::process::Stdio::null())
-        .status()
-        .map(|s| s.success())
-        .unwrap_or(false);
-
-    #[cfg(not(target_os = "windows"))]
-    let check = std::process::Command::new("which")
-        .arg(cmd)
-        .stdout(std::process::Stdio::null())
-        .stderr(std::process::Stdio::null())
-        .status()
-        .map(|s| s.success())
-        .unwrap_or(false);
+/// PATH (Windows 는 PATHEXT 포함) 에서 명령어의 실제 실행 파일 경로를 resolve 한다.
+///
+/// P87 (issue #92): Windows 에서 npm 으로 설치된 CLI (codex, claude 등) 는
+/// `codex.cmd` 같은 배치 래퍼다. `std::process::Command::new("codex")` 는
+/// PATHEXT 를 적용하지 않아 `.exe` 만 찾고 `.cmd` 는 "program not found" 로
+/// 실패한다. `which` crate 는 PATHEXT 를 적용해 `.cmd`/`.bat`/`.exe` 를 모두
+/// 탐색하므로 실제 경로를 얻을 수 있고, Rust 1.77+ 는 `.cmd`/`.bat` 확장자가
+/// 포함된 경로를 `Command` 로 실행하면 cmd.exe 를 경유해 안전하게 실행한다.
+///
+/// resolve 실패 시 입력 문자열을 그대로 `PathBuf` 로 반환한다 (기존 동작 유지).
+pub fn resolve_program(cmd: &str) -> std::path::PathBuf {
+    which::which(cmd).unwrap_or_else(|_| std::path::PathBuf::from(cmd))
+}
 
-    check
+/// 크로스플랫폼 명령어 존재 확인.
+///
+/// P87 (issue #92): 외부 `where.exe` / `which` 프로세스 호출 대신 `which` crate
+/// 사용 — Windows PATHEXT (`.cmd` 등) 를 적용하고, spawn 시 쓰는 [`resolve_program`]
+/// 과 동일한 탐색 규칙이라 "존재하지만 spawn 실패" 불일치를 제거한다.
+pub fn command_exists(cmd: &str) -> bool {
+    which::which(cmd).is_ok()
 }
 
 #[cfg(test)]
diff --git a/crates/secall-core/src/search/query_expand.rs b/crates/secall-core/src/search/query_expand.rs
index 1efc9b2..25b7818 100644
--- a/crates/secall-core/src/search/query_expand.rs
+++ b/crates/secall-core/src/search/query_expand.rs
@@ -28,7 +28,7 @@ pub fn expand_query(query: &str, db: Option<&Database>) -> Result<String> {
          쿼리: {query}"
     );
 
-    let output = std::process::Command::new("claude")
+    let output = std::process::Command::new(crate::resolve_program("claude"))
         .args(["-p", &prompt, "--model", "claude-haiku-4-5-20251001"])
         .output()?;
 
diff --git a/crates/secall-core/src/wiki/claude.rs b/crates/secall-core/src/wiki/claude.rs
index 53d5a75..7e80d88 100644
--- a/crates/secall-core/src/wiki/claude.rs
+++ b/crates/secall-core/src/wiki/claude.rs
@@ -36,7 +36,7 @@ impl WikiBackend for ClaudeBackend {
             _ => "claude-sonnet-4-6",
         };
 
-        let mut child = tokio::process::Command::new("claude")
+        let mut child = tokio::process::Command::new(crate::resolve_program("claude"))
             .args(["-p", "--model", model_id])
             .arg("--allowedTools")
             .arg("mcp__secall__recall,mcp__secall__get,mcp__secall__status,mcp__secall__wiki_search,Read,Write,Edit,Glob,Grep")
diff --git a/crates/secall-core/src/wiki/codex.rs b/crates/secall-core/src/wiki/codex.rs
index e873e31..11ad3ee 100644
--- a/crates/secall-core/src/wiki/codex.rs
+++ b/crates/secall-core/src/wiki/codex.rs
@@ -27,7 +27,7 @@ impl WikiBackend for CodexBackend {
         let output_file = tempfile::NamedTempFile::new()?;
         let output_path = output_file.path().to_path_buf();
 
-        let mut child = tokio::process::Command::new("codex")
+        let mut child = tokio::process::Command::new(crate::resolve_program("codex"))
             .args([
                 "exec",
                 "--skip-git-repo-check",
diff --git a/crates/secall-core/src/wiki/reviewers/claude.rs b/crates/secall-core/src/wiki/reviewers/claude.rs
index 6d16e2e..aa8abb2 100644
--- a/crates/secall-core/src/wiki/reviewers/claude.rs
+++ b/crates/secall-core/src/wiki/reviewers/claude.rs
@@ -39,6 +39,9 @@ async fn run_review_cli(
         anyhow::bail!("{bin} CLI not found in PATH");
     }
 
+    // Gemini PR #96: PATH 탐색 (disk I/O) 은 루프 밖에서 1회만.
+    let program = crate::resolve_program(bin);
+
     for strict in [false, true] {
         let prompt = format!(
             "{}\n\n{}",
@@ -46,7 +49,7 @@ async fn run_review_cli(
             super::build_user_prompt(page_content, source_summary, strict)
         );
 
-        let mut child = tokio::process::Command::new(bin);
+        let mut child = tokio::process::Command::new(&program);
         child
             .args(args)
             .stdin(Stdio::piped())
diff --git a/crates/secall-core/src/wiki/reviewers/codex.rs b/crates/secall-core/src/wiki/reviewers/codex.rs
index 50851b6..45ea00e 100644
--- a/crates/secall-core/src/wiki/reviewers/codex.rs
+++ b/crates/secall-core/src/wiki/reviewers/codex.rs
@@ -19,6 +19,9 @@ impl WikiReviewer for CodexReviewer {
             anyhow::bail!("codex CLI not found in PATH");
         }
 
+        // Gemini PR #96: PATH 탐색 (disk I/O) 은 루프 밖에서 1회만.
+        let program = crate::resolve_program("codex");
+
         for strict in [false, true] {
             let prompt = format!(
                 "{}\n\n{}",
@@ -29,7 +32,7 @@ impl WikiReviewer for CodexReviewer {
             let output_file = tempfile::NamedTempFile::new()?;
             let output_path = output_file.path().to_path_buf();
 
-            let mut child = tokio::process::Command::new("codex");
+            let mut child = tokio::process::Command::new(&program);
             child
                 .args([
                     "exec",
diff --git a/docs/plans/index.md b/docs/plans/index.md
index 3b5260b..ba1387b 100644
--- a/docs/plans/index.md
+++ b/docs/plans/index.md
@@ -166,3 +166,11 @@ Plan document index. Register new plans here.
 - [전체 계획서](p86-ollama-batch-fail-fast.md) — in_progress, 2026-05-19
 - 단일 Task: `commands/wiki.rs` 의 backend 선택 직후 ollama/lmstudio 차단 + 가이드 메시지. silent 30분 wait 사고 차단.
 - 관련: issue #88 (cakel).
+
+---
+
+### seCall P87 — Windows `.cmd` 래퍼 CLI spawn 실패 fix (issue #92)
+
+- [전체 계획서](p87-windows-cmd-spawn.md) — in_progress, 2026-05-29
+- 단일 Task: `which` crate 로 `resolve_program` 추가 — Windows PATHEXT 적용해 npm `.cmd` 래퍼 (codex/claude) 를 정상 spawn. spawn 5곳 + `command_exists` 통일.
+- 관련: issue #92 (cakel).
diff --git a/docs/plans/p87-windows-cmd-spawn.md b/docs/plans/p87-windows-cmd-spawn.md
new file mode 100644
index 0000000..d97cfa1
--- /dev/null
+++ b/docs/plans/p87-windows-cmd-spawn.md
@@ -0,0 +1,90 @@
+---
+type: plan
+status: in_progress
+updated_at: 2026-05-29
+canonical: true
+---
+
+# P87 — Windows `.cmd` 래퍼 CLI spawn 실패 fix (issue #92)
+
+## 배경
+
+Issue #92 (cakel, Windows 10): `secall wiki update --backend codex` 실행 시:
+```
+Wiki update: all sessions (backend: codex)
+  Launching codex...
+Error: program not found
+```
+`where codex` 는 `codex.cmd` + `codex` 를 찾고 `codex` 명령 자체도 동작하는데 secall 만 실패.
+
+## 원인
+
+- codex 는 npm 으로 설치되어 `C:\Users\User\AppData\Roaming\npm\codex.cmd` (배치 래퍼) 형태다.
+- `std::process::Command::new("codex")` 는 Windows 에서 **PATHEXT 를 적용하지 않아** `codex.exe` 만 시도하고 `codex.cmd` 는 못 찾아 "program not found".
+- 반면 `command_exists` 는 `where.exe codex` 외부 호출로 `.cmd` 를 찾으므로 **통과** → "존재하는데 spawn 실패" 불일치.
+
+## 목표
+
+- Windows 에서 npm `.cmd` 래퍼 CLI (codex / claude) 를 정상 spawn.
+- macOS / Linux 회귀 없음.
+- "존재 확인" 과 "실제 spawn" 의 탐색 규칙 일치.
+
+## 비목표
+
+- codex/claude 외 다른 외부 명령 (ollama, git) 의 동작 변경 없음 (영향 받지만 회귀 없음).
+
+## 구현
+
+### 1. `which` crate 도입
+
+`Cargo.toml` workspace dep `which = "8"` + `secall-core/Cargo.toml` `which.workspace = true`.
+
+`which` 는 Windows 에서 PATHEXT (`.CMD`/`.EXE`/`.BAT`) 를 적용해 실제 경로를 탐색한다.
+
+### 2. `lib.rs` — `resolve_program` + `command_exists` 재구현
+
+```rust
+pub fn resolve_program(cmd: &str) -> std::path::PathBuf {
+    which::which(cmd).unwrap_or_else(|_| std::path::PathBuf::from(cmd))
+}
+
+pub fn command_exists(cmd: &str) -> bool {
+    which::which(cmd).is_ok()
+}
+```
+
+`resolve_program` 이 `codex.cmd` 풀경로를 반환 → Rust 1.77+ 가 `.cmd`/`.bat` 확장자 경로를 `Command` 로 실행 시 cmd.exe 경유로 안전 실행 (인자 escaping 포함).
+
+### 3. spawn 사이트 5곳 — `Command::new(resolve_program(X))`
+
+| 파일 | 명령 |
+|---|---|
+| `wiki/codex.rs:30` | codex |
+| `wiki/claude.rs:39` | claude |
+| `wiki/reviewers/codex.rs:32` | codex |
+| `wiki/reviewers/claude.rs` (`run_review_cli`) | bin (claude/codex) |
+| `search/query_expand.rs:31` | claude |
+
+## 변경 파일
+
+- `Cargo.toml`, `crates/secall-core/Cargo.toml` — which dep
+- `crates/secall-core/src/lib.rs` — resolve_program + command_exists
+- `crates/secall-core/src/wiki/{codex,claude}.rs`
+- `crates/secall-core/src/wiki/reviewers/{codex,claude}.rs`
+- `crates/secall-core/src/search/query_expand.rs`
+- `docs/plans/p87-windows-cmd-spawn.md` (신규) + `docs/plans/index.md`
+
+## 검증
+
+```bash
+cargo fmt --all -- --check
+cargo clippy --workspace --all-targets -- -D warnings
+cargo test -p secall-core --lib   # command_exists 회귀 (3건)
+```
+
+⚠️ **Windows 실제 spawn 검증 불가** (개발 환경 macOS). 머지 전 cakel (issue #92 보고자) 에게 Windows 빌드 검증 요청 필요. macOS/Linux 는 `which` 가 확장자 없는 실행파일 그대로 resolve → 회귀 없음 (위 테스트 통과 확인).
+
+## 리스크
+
+- `which` resolve 실패 시 입력 문자열 그대로 fallback → 기존 동작 유지 (최소 회귀).
+- Rust 1.77+ 의 `.cmd` 자동 cmd.exe 경유 실행에 의존 — secall MSRV 1.75 보다 높음. 단 실제 빌드/CI 는 최신 toolchain (1.94) 사용. MSRV 표기는 별도 검토 (본 PR 범위 외 — 코드는 1.75 에서도 컴파일됨, .cmd 실행 동작만 1.77+).