diff --git a/docs/fixes/INSTALL-HOOK-WRAPPER-FIX-20260422.md b/docs/fixes/INSTALL-HOOK-WRAPPER-FIX-20260422.md
new file mode 100644
index 00000000..0572f85f
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+++ b/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.
+
+## PowerShell 5.1 compatibility
+
+`ConvertFrom-Json -AsHashtable` is PowerShell 7+ only. The script tries
+`-AsHashtable` first and falls back to a manual `PSCustomObject` →
+`Hashtable` conversion on Windows PowerShell 5.1. Both hook buckets
+(`PreToolUse`, `PostToolUse`) and their inner `hooks` arrays are
+materialized as `System.Collections.ArrayList` before serialization, so
+PS 5.1's `ConvertTo-Json` cannot collapse single-element arrays into
+bare objects. Verified by running `powershell -NoProfile -File
+docs/fixes/install_hook_wrapper.ps1` on a Windows 11 machine with only
+Windows PowerShell 5.1 installed (no `pwsh`).
+
+## 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`
+- PR #1542 — `patch_settings_cl_v2_simple.ps1` companion fix
diff --git a/docs/fixes/install_hook_wrapper.ps1 b/docs/fixes/install_hook_wrapper.ps1
new file mode 100644
index 00000000..01809708
--- /dev/null
+++ b/docs/fixes/install_hook_wrapper.ps1
@@ -0,0 +1,167 @@
+# Install observe-wrapper.sh + rewrite settings.local.json to use it
+# No Japanese literals - uses $PSScriptRoot instead
+# argv-dup bug workaround: use `bash` (PATH-resolved) as first token and
+# normalize wrapper path to forward slashes. See PR #1524.
+#
+# PowerShell 5.1 compatibility:
+#   - `ConvertFrom-Json -AsHashtable` is PS 7+ only; fall back to a manual
+#     PSCustomObject -> Hashtable conversion on Windows PowerShell 5.1.
+#   - PS 5.1 `ConvertTo-Json` collapses single-element arrays inside
+#     Hashtables into bare objects. Normalize the hook buckets
+#     (PreToolUse / PostToolUse) and their inner `hooks` arrays as
+#     `System.Collections.ArrayList` before serialization to preserve
+#     array shape.
+$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: $WrapperSrc" -ForegroundColor Red
+    exit 1
+}
+
+# Ensure the hook destination directory exists (fresh installs have no
+# skills/continuous-learning/hooks tree yet).
+$dstDir = Split-Path $WrapperDst
+if (-not (Test-Path $dstDir)) {
+    New-Item -ItemType Directory -Path $dstDir -Force | Out-Null
+}
+
+# --- Helpers ------------------------------------------------------------
+
+# Convert a PSCustomObject tree (as returned by ConvertFrom-Json on PS 5.1)
+# into nested Hashtables/ArrayLists so the merge logic below works uniformly
+# and so ConvertTo-Json preserves single-element arrays on PS 5.1.
+function ConvertTo-HashtableRecursive {
+    param($InputObject)
+    if ($null -eq $InputObject) { return $null }
+    if ($InputObject -is [System.Collections.IDictionary]) {
+        $result = @{}
+        foreach ($key in $InputObject.Keys) {
+            $result[$key] = ConvertTo-HashtableRecursive -InputObject $InputObject[$key]
+        }
+        return $result
+    }
+    if ($InputObject -is [System.Management.Automation.PSCustomObject]) {
+        $result = @{}
+        foreach ($prop in $InputObject.PSObject.Properties) {
+            $result[$prop.Name] = ConvertTo-HashtableRecursive -InputObject $prop.Value
+        }
+        return $result
+    }
+    if ($InputObject -is [System.Collections.IList] -or $InputObject -is [System.Array]) {
+        $list = [System.Collections.ArrayList]::new()
+        foreach ($item in $InputObject) {
+            $null = $list.Add((ConvertTo-HashtableRecursive -InputObject $item))
+        }
+        return ,$list
+    }
+    return $InputObject
+}
+
+function Read-SettingsAsHashtable {
+    param([string]$Path)
+    $raw = Get-Content -Raw -Path $Path -Encoding UTF8
+    if ([string]::IsNullOrWhiteSpace($raw)) { return @{} }
+    try {
+        return ($raw | ConvertFrom-Json -AsHashtable)
+    } catch {
+        $obj = $raw | ConvertFrom-Json
+        return (ConvertTo-HashtableRecursive -InputObject $obj)
+    }
+}
+
+function ConvertTo-ArrayList {
+    param($Value)
+    $list = [System.Collections.ArrayList]::new()
+    foreach ($item in @($Value)) { $null = $list.Add($item) }
+    return ,$list
+}
+
+# --- 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
+if (-not (Test-Path $SettingsPath)) {
+    Write-Host "[ERROR] Settings file not found: $SettingsPath" -ForegroundColor Red
+    Write-Host "  Run patch_settings_cl_v2_simple.ps1 first to bootstrap the file." -ForegroundColor Yellow
+    exit 1
+}
+$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 = Read-SettingsAsHashtable -Path $SettingsPath
+
+# Normalize wrapper path to forward slashes so bash (MSYS/Git Bash) does not
+# mangle backslashes; quoting keeps spaces safe.
+$wrapperPath = $WrapperDst -replace '\\','/'
+$preCmd  = $BashExe + ' "' + $wrapperPath + '" pre'
+$postCmd = $BashExe + ' "' + $wrapperPath + '" post'
+
+if (-not $settings.ContainsKey("hooks") -or $null -eq $settings["hooks"]) {
+    $settings["hooks"] = @{}
+}
+foreach ($key in @("PreToolUse", "PostToolUse")) {
+    if (-not $settings.hooks.ContainsKey($key) -or $null -eq $settings.hooks[$key]) {
+        $settings.hooks[$key] = [System.Collections.ArrayList]::new()
+    } elseif (-not ($settings.hooks[$key] -is [System.Collections.ArrayList])) {
+        $settings.hooks[$key] = (ConvertTo-ArrayList -Value $settings.hooks[$key])
+    }
+    # Inner `hooks` arrays need the same ArrayList normalization to
+    # survive PS 5.1 ConvertTo-Json serialization.
+    foreach ($entry in $settings.hooks[$key]) {
+        if ($entry -is [System.Collections.IDictionary] -and $entry.ContainsKey("hooks") -and
+            -not ($entry["hooks"] -is [System.Collections.ArrayList])) {
+            $entry["hooks"] = (ConvertTo-ArrayList -Value $entry["hooks"])
+        }
+    }
+}
+
+# Point every existing hook command at the wrapper with the appropriate
+# positional argument. The entry shape is preserved exactly; only the
+# `command` field is rewritten.
+foreach ($entry in $settings.hooks.PreToolUse) {
+    foreach ($h in @($entry.hooks)) {
+        if ($h -is [System.Collections.IDictionary]) { $h["command"] = $preCmd }
+    }
+}
+foreach ($entry in $settings.hooks.PostToolUse) {
+    foreach ($h in @($entry.hooks)) {
+        if ($h -is [System.Collections.IDictionary]) { $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"