fix(hooks): avoid Claude Code v2.1.116 argv-dup bug in settings.local.json (#1524)

* fix: resolve Claude Code Bash hook "cannot execute binary file" on Windows

Root cause in ~/.claude/settings.local.json (user-global):
1. UTF-8 BOM + CRLF line endings left by patch_settings_cl_v2_simple.ps1
2. Double-wrapped command "\"bash.exe\" \"wrapper.sh\"" broke Windows
   argument splitting on the space in "Program Files", making bash.exe
   try to execute itself as a script.

Fix:
- Rewrite settings.local.json as UTF-8 (no BOM), LF, with the hook command
  pointing directly at observe-wrapper.sh and passing "pre"/"post" as a
  positional arg so HOOK_PHASE is populated correctly in observe.sh.

Docs:
- docs/fixes/HOOK-FIX-20260421.md — full root-cause analysis.
- docs/fixes/apply-hook-fix.sh — idempotent applier script.

* docs: addendum for HOOK-FIX-20260421 (v2.1.116 argv duplication detail)

- Documents Claude Code v2.1.116 argv duplication bug as the underlying
  cause of the bash.exe:bash.exe:cannot execute binary file error
- Records night-session fix variant using explicit `bash <path>` prefix
  (matches hooks.json observer pattern, avoids EFTYPE on Node spawn)
- Keeps morning commit 527c18b intact; both variants are now documented

---------

Co-authored-by: suusuu0927 <sugi.go.go.gm@gmail.com>

docs/fixes/HOOK-FIX-20260421-ADDENDUM.md

@@ -0,0 +1,109 @@
+# HOOK-FIX-20260421 Addendum — v2.1.116 argv 重複バグ
+
+朝セッションで commit 527c18b として修正済み。夜セッションで追加検証と、
+朝fix でカバーしきれない Claude Code 固有のバグを特定したので補遺を記録する。
+
+## 朝fixの形式
+
+```json
+"command": "C:/Users/sugig/.claude/skills/continuous-learning/hooks/observe-wrapper.sh pre"
+```
+
+`.sh` ファイルを直接 command にする形式。Git Bash が shebang 経由で実行する前提。
+
+## 夜 追加検証で判明したこと
+
+Node.js の `child_process.spawn` で `.sh` ファイルを直接実行すると Windows では
+**EFTYPE** で失敗する：
+
+```js
+spawn('C:/Users/sugig/.claude/skills/continuous-learning/hooks/observe-wrapper.sh', 
+      ['post'], {stdio:['pipe','pipe','pipe']});
+// → Error: spawn EFTYPE (errno -4028)
+```
+
+`shell:true` を付ければ cmd.exe 経由で実行できるが、Claude Code 側の実装
+依存のリスクが残る。
+
+## 夜 適用した追加 fix
+
+第1トークンを `bash`（PATH 解決）に変えた明示的な呼び出しに更新：
+
+```json
+{
+  "hooks": {
+    "PreToolUse": [{
+      "matcher": "*",
+      "hooks": [{
+        "type": "command",
+        "command": "bash \"C:/Users/sugig/.claude/skills/continuous-learning/hooks/observe-wrapper.sh\" pre"
+      }]
+    }],
+    "PostToolUse": [{
+      "matcher": "*",
+      "hooks": [{
+        "type": "command",
+        "command": "bash \"C:/Users/sugig/.claude/skills/continuous-learning/hooks/observe-wrapper.sh\" post"
+      }]
+    }]
+  }
+}
+```
+
+この形式は `~/.claude/hooks/hooks.json` 内の ECC 正規 observer 登録と
+同じパターンで、現実にエラーなく動作している実績あり。
+
+### Node spawn 検証
+
+```js
+spawn('bash "C:/Users/sugig/.claude/skills/continuous-learning/hooks/observe-wrapper.sh" post',
+      [], {shell:true});
+// exit=0 → observations.jsonl に正常追記
+```
+
+## Claude Code v2.1.116 の argv 重複バグ（詳細）
+
+朝fix docの「Defect 2」として `bash.exe: bash.exe: cannot execute binary file` を
+記録しているが、その根本メカニズムが特定できたので記す。
+
+### 再現
+
+```bash
+"C:\Program Files\Git\bin\bash.exe" "C:\Program Files\Git\bin\bash.exe"
+# stderr: "C:\Program Files\Git\bin\bash.exe: C:\Program Files\Git\bin\bash.exe: cannot execute binary file"
+# exit: 126
+```
+
+bash は argv[1] を script とみなし読み込もうとする。argv[1] が bash.exe 自身なら
+ELF/PE バイナリ検出で失敗 → exit 126。エラー文言は完全一致。
+
+### Claude Code 側の挙動
+
+hook command が `"C:\Program Files\Git\bin\bash.exe" "C:\Users\...\wrapper.sh"`
+のとき、v2.1.116 は**第1トークン（= bash.exe フルパス）を argv[0] と argv[1] の
+両方に渡す**と推定される。結果 bash は argv[1] = bash.exe を script として
+読み込もうとして 126 で落ちる。
+
+### 回避策
+
+第1トークンを bash.exe のフルパス＋スペース付きパスにしないこと：
+1. ✅ `bash` （PATH 解決の単一トークン）— 夜fix / hooks.json パターン
+2. ✅ `.sh` 直接パス（Claude Code の .sh ハンドリングに依存）— 朝fix
+3. ❌ `"C:\Program Files\Git\bin\bash.exe" "<path>"` — 1トークン目が quoted で空白込み
+
+## 結論
+
+朝fix（直接 .sh 指定）と夜fix（明示的 bash prefix）のどちらも argv 重複バグを
+踏まないが、**夜fixの方が Claude Code の実装依存が少ない**ため推奨。
+
+ただし朝fix commit 527c18b は既に docs/fixes/ に入っているため、この Addendum を
+追記することで両論併記とする。次回 CLI 再起動時に夜fix の方が実運用に残る。
+
+## 関連
+
+- 朝 fix commit: 527c18b
+- 朝 fix doc: docs/fixes/HOOK-FIX-20260421.md
+- 朝 apply script: docs/fixes/apply-hook-fix.sh
+- 夜 fix 記録（ローカル）: C:\Users\sugig\Documents\Claude\Projects\ECC作成\hook-fix-report-20260421.md
+- 夜 fix 適用ファイル: C:\Users\sugig\.claude\settings.local.json
+- 夜 backup: C:\Users\sugig\.claude\settings.local.json.bak-hook-fix-20260421

docs/fixes/HOOK-FIX-20260421.md

@@ -0,0 +1,144 @@
+# ECC Hook Fix — 2026-04-21
+
+## Summary
+
+Claude Code CLI v2.1.116 on Windows was failing all Bash tool hook invocations with:
+
+```
+PreToolUse:Bash hook error
+Failed with non-blocking status code:
+C:\Program Files\Git\bin\bash.exe: C:\Program Files\Git\bin\bash.exe:
+cannot execute binary file
+
+PostToolUse:Bash hook error  (同上)
+```
+
+Result: `observations.jsonl` stopped updating after `2026-04-20T23:03:38Z`
+(last entry was a `parse_error` from an earlier BOM-on-stdin issue).
+
+## Root Cause
+
+`C:\Users\sugig\.claude\settings.local.json` had two defects:
+
+### Defect 1 — UTF-8 BOM + CRLF line endings
+
+The file started with `EF BB BF` (UTF-8 BOM) and used `CRLF` line terminators.
+This is the PowerShell `ConvertTo-Json | Out-File` default behavior, and it is
+what `patch_settings_cl_v2_simple.ps1` leaves behind when it rewrites the file.
+
+```
+00000000: efbb bf7b 0d0a 2020 2020 2268 6f6f 6b73  ...{..    "hooks
+```
+
+### Defect 2 — Double-wrapped bash.exe invocation
+
+The command string explicitly re-invoked bash.exe:
+
+```json
+"command": "\"C:\\Program Files\\Git\\bin\\bash.exe\" \"C:\\Users\\sugig\\.claude\\skills\\continuous-learning\\hooks\\observe-wrapper.sh\""
+```
+
+When Claude Code spawns this on Windows, argument splitting does not preserve
+the quoted `"C:\Program Files\..."` token correctly. The embedded space in
+`Program Files` splits `argv[0]`, and `bash.exe` ends up being passed to
+itself as a script file, producing:
+
+```
+bash.exe: bash.exe: cannot execute binary file
+```
+
+### Prior working shape (for reference)
+
+Before `patch_settings_cl_v2_simple.ps1` ran, the command was simply:
+
+```json
+"command": "C:\\Users\\sugig\\.claude\\skills\\continuous-learning\\hooks\\observe.sh"
+```
+
+Claude Code on Windows detects `.sh` and invokes it via Git Bash itself — no
+manual `bash.exe` wrapping needed.
+
+## Fix
+
+`C:\Users\sugig\.claude\settings.local.json` rewritten as UTF-8 (no BOM), LF
+line endings, with the command pointing directly at the wrapper `.sh` and
+passing the hook phase as a plain argument:
+
+```json
+{
+  "hooks": {
+    "PreToolUse": [
+      {
+        "matcher": "*",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "C:/Users/sugig/.claude/skills/continuous-learning/hooks/observe-wrapper.sh pre"
+          }
+        ]
+      }
+    ],
+    "PostToolUse": [
+      {
+        "matcher": "*",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "C:/Users/sugig/.claude/skills/continuous-learning/hooks/observe-wrapper.sh post"
+          }
+        ]
+      }
+    ]
+  }
+}
+```
+
+Side benefit: the `pre` / `post` argument is now routed to `observe.sh`'s
+`HOOK_PHASE` variable so events are correctly logged as `tool_start` vs
+`tool_complete` (previously everything was recorded as `tool_complete`).
+
+## Verification
+
+Direct invocation of the new command format, emulating both hook phases:
+
+```bash
+# PostToolUse path
+echo '{"tool_name":"Bash","tool_input":{"command":"pwd"},"session_id":"post-fix-verify-001","cwd":"...","hook_event_name":"PostToolUse"}' \
+  | "C:/Users/sugig/.claude/skills/continuous-learning/hooks/observe-wrapper.sh" post
+# exit=0
+
+# PreToolUse path
+echo '{"tool_name":"Bash","tool_input":{"command":"ls"},"session_id":"post-fix-verify-pre-001","cwd":"...","hook_event_name":"PreToolUse"}' \
+  | "C:/Users/sugig/.claude/skills/continuous-learning/hooks/observe-wrapper.sh" pre
+# exit=0
+```
+
+`observations.jsonl` gained:
+
+```
+{"timestamp":"2026-04-21T05:57:54Z","event":"tool_complete","tool":"Bash","session":"post-fix-verify-001",...}
+{"timestamp":"2026-04-21T05:57:55Z","event":"tool_start","tool":"Bash","session":"post-fix-verify-pre-001","input":"{\"command\":\"ls\"}",...}
+```
+
+Both phases now produce correctly typed events.
+
+**Note on live CLI verification:** settings changes take effect on the next
+`claude` CLI session launch. Restart the CLI and run a Bash tool call to
+confirm new rows appear in `observations.jsonl` from the actual CLI session.
+
+## Files Touched
+
+- `C:\Users\sugig\.claude\settings.local.json` — rewritten
+- `C:\Users\sugig\.claude\settings.local.json.bak-hookfix-20260421-145718` — pre-fix backup
+
+## Known Upstream Bugs (not fixed here)
+
+- `install_hook_wrapper.ps1` — halts at step [3/4], never reaches [4/4].
+- `patch_settings_cl_v2_simple.ps1` — overwrites `settings.local.json` with
+  UTF-8-BOM + CRLF and re-introduces the double-wrapped `bash.exe` command.
+  Should be replaced with a patcher that emits UTF-8 (no BOM), LF, and a
+  direct `.sh` path.
+
+## Branch
+
+`claude/hook-fix-20260421`

docs/fixes/apply-hook-fix.sh

@@ -0,0 +1,60 @@
+#!/usr/bin/env bash
+# Apply ECC hook fix to ~/.claude/settings.local.json.
+#
+# - Creates a timestamped backup next to the original.
+# - Rewrites the file as UTF-8 (no BOM), LF line endings.
+# - Routes hook commands directly at observe-wrapper.sh with a "pre"/"post" arg.
+#
+# Related fix doc: docs/fixes/HOOK-FIX-20260421.md
+
+set -euo pipefail
+
+TARGET="${1:-$HOME/.claude/settings.local.json}"
+WRAPPER="${ECC_OBSERVE_WRAPPER:-$HOME/.claude/skills/continuous-learning/hooks/observe-wrapper.sh}"
+
+if [ ! -f "$WRAPPER" ]; then
+  echo "[hook-fix] wrapper not found: $WRAPPER" >&2
+  exit 1
+fi
+
+mkdir -p "$(dirname "$TARGET")"
+
+if [ -f "$TARGET" ]; then
+  ts="$(date +%Y%m%d-%H%M%S)"
+  cp "$TARGET" "$TARGET.bak-hookfix-$ts"
+  echo "[hook-fix] backup: $TARGET.bak-hookfix-$ts"
+fi
+
+# Convert wrapper path to forward-slash form for JSON.
+wrapper_fwd="$(printf '%s' "$WRAPPER" | tr '\\\\' '/')"
+
+# Write the new config as UTF-8 (no BOM), LF line endings.
+printf '%s\n' '{
+  "hooks": {
+    "PreToolUse": [
+      {
+        "matcher": "*",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "'"$wrapper_fwd"' pre"
+          }
+        ]
+      }
+    ],
+    "PostToolUse": [
+      {
+        "matcher": "*",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "'"$wrapper_fwd"' post"
+          }
+        ]
+      }
+    ]
+  }
+}' > "$TARGET"
+
+echo "[hook-fix] wrote: $TARGET"
+echo "[hook-fix] restart the claude CLI for changes to take effect"