fix(hooks): rewrite install_hook_wrapper.ps1 to avoid argv-dup bug

Under Claude Code v2.1.116 the first argv token of a hook command is
duplicated. When the token is a quoted Windows .exe path, bash.exe is
re-invoked with itself as script (exit 126). PR #1524 fixed the shape
of settings.local.json; this script keeps the installer consistent so
re-running it does not regenerate the broken form.

Changes:
- First token is now PATH-resolved `bash` instead of the quoted bash.exe
- Wrapper path is normalized to forward slashes for MSYS safety
- PreToolUse and PostToolUse get distinct pre/post positional arguments
- JSON output is written with LF endings (no mixed CRLF/LF)

Companion doc: docs/fixes/INSTALL-HOOK-WRAPPER-FIX-20260422.md

docs/fixes/INSTALL-HOOK-WRAPPER-FIX-20260422.md

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+# install_hook_wrapper.ps1 argv-dup bug workaround (2026-04-22)
+
+## Summary
+
+`docs/fixes/install_hook_wrapper.ps1` is the PowerShell helper that copies
+`observe-wrapper.sh` into `~/.claude/skills/continuous-learning/hooks/` and
+rewrites `~/.claude/settings.local.json` so the observer hook points at it.
+
+The previous version produced a hook command of the form:
+
+```
+"C:\Program Files\Git\bin\bash.exe" "C:\Users\...\observe-wrapper.sh"
+```
+
+Under Claude Code v2.1.116 the first argv token is duplicated. When that token
+is a quoted Windows executable path, `bash.exe` is re-invoked with itself as
+its `$0`, which fails with `cannot execute binary file` (exit 126). PR #1524
+documents the root cause; this script is a companion that keeps the installer
+in sync with the fixed `settings.local.json` layout.
+
+## What the fix does
+
+- First token is now the PATH-resolved `bash` (no quoted `.exe` path), so the
+  argv-dup bug no longer passes a binary as a script.
+- The wrapper path is normalized to forward slashes before it is embedded in
+  the hook command, avoiding MSYS backslash handling surprises.
+- `PreToolUse` and `PostToolUse` receive distinct commands with explicit
+  `pre` / `post` positional arguments, matching the shape the wrapper expects.
+- The settings file is written with LF line endings so downstream JSON parsers
+  never see mixed CRLF/LF output from `ConvertTo-Json`.
+
+## Resulting command shape
+
+```
+bash "C:/Users/<you>/.claude/skills/continuous-learning/hooks/observe-wrapper.sh" pre
+bash "C:/Users/<you>/.claude/skills/continuous-learning/hooks/observe-wrapper.sh" post
+```
+
+## Usage
+
+```powershell
+# Place observe-wrapper.sh next to this script, then:
+pwsh -File docs/fixes/install_hook_wrapper.ps1
+```
+
+The script backs up `settings.local.json` to
+`settings.local.json.bak-<timestamp>` before writing.
+
+## Related
+
+- PR #1524 — settings.local.json shape fix (same argv-dup root cause)
+- PR #1511 — skip `AppInstallerPythonRedirector.exe` in observer python resolution
+- PR #1539 — locale-independent `detect-project.sh`

docs/fixes/install_hook_wrapper.ps1

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+# Install observe-wrapper.sh + rewrite settings.local.json to use it
+# No Japanese literals - uses $PSScriptRoot instead
+# argv-dup bug workaround: use `bash` (PATH-resolved) as first token and
+# normalize wrapper path to forward slashes. See PR #1524.
+$ErrorActionPreference = "Stop"
+
+$SkillHooks   = "$env:USERPROFILE\.claude\skills\continuous-learning\hooks"
+$WrapperSrc   = Join-Path $PSScriptRoot "observe-wrapper.sh"
+$WrapperDst   = "$SkillHooks\observe-wrapper.sh"
+$SettingsPath = "$env:USERPROFILE\.claude\settings.local.json"
+# Use PATH-resolved `bash` to avoid Claude Code v2.1.116 argv-dup bug that
+# double-passes the first token when the quoted path is a Windows .exe.
+$BashExe      = "bash"
+
+Write-Host "=== Install Hook Wrapper ===" -ForegroundColor Cyan
+Write-Host "ScriptRoot: $PSScriptRoot"
+Write-Host "WrapperSrc: $WrapperSrc"
+
+if (-not (Test-Path $WrapperSrc)) {
+    Write-Host "[ERROR] Source not found: $WrapperSrc" -ForegroundColor Red
+    exit 1
+}
+
+# 1) Copy wrapper + LF normalization
+Write-Host "[1/4] Copy wrapper to $WrapperDst" -ForegroundColor Yellow
+$content = Get-Content -Raw -Path $WrapperSrc
+$contentLf = $content -replace "`r`n","`n"
+$utf8 = [System.Text.UTF8Encoding]::new($false)
+[System.IO.File]::WriteAllText($WrapperDst, $contentLf, $utf8)
+Write-Host "  [OK] wrapper installed with LF endings" -ForegroundColor Green
+
+# 2) Backup settings
+Write-Host "[2/4] Backup settings.local.json" -ForegroundColor Yellow
+$backup = "$SettingsPath.bak-$(Get-Date -Format 'yyyyMMdd-HHmmss')"
+Copy-Item $SettingsPath $backup -Force
+Write-Host "  [OK] $backup" -ForegroundColor Green
+
+# 3) Rewrite command path in settings.local.json
+Write-Host "[3/4] Rewrite hook command to wrapper" -ForegroundColor Yellow
+$settings = Get-Content -Raw -Path $SettingsPath -Encoding UTF8 | ConvertFrom-Json -AsHashtable
+
+# Normalize wrapper path to forward slashes so bash (MSYS/Git Bash) does not
+# mangle backslashes; quoting keeps spaces safe.
+$wrapperPath = $WrapperDst -replace '\\','/'
+$preCmd  = $BashExe + ' "' + $wrapperPath + '" pre'
+$postCmd = $BashExe + ' "' + $wrapperPath + '" post'
+
+foreach ($entry in $settings.hooks.PreToolUse) {
+    foreach ($h in $entry.hooks) {
+        $h.command = $preCmd
+    }
+}
+foreach ($entry in $settings.hooks.PostToolUse) {
+    foreach ($h in $entry.hooks) {
+        $h.command = $postCmd
+    }
+}
+
+$json = $settings | ConvertTo-Json -Depth 20
+# Normalize CRLF -> LF so hook parsers never see mixed line endings.
+$jsonLf = $json -replace "`r`n","`n"
+[System.IO.File]::WriteAllText($SettingsPath, $jsonLf, $utf8)
+Write-Host "  [OK] command updated" -ForegroundColor Green
+Write-Host "  PreToolUse  command: $preCmd"
+Write-Host "  PostToolUse command: $postCmd"
+
+# 4) Verify
+Write-Host "[4/4] Verify" -ForegroundColor Yellow
+Get-Content $SettingsPath | Select-String "command"
+
+Write-Host ""
+Write-Host "=== DONE ===" -ForegroundColor Green
+Write-Host "Next: Launch Claude CLI and run any command to trigger observations.jsonl"