feat: Claude Code pre-bash hooks for PowerShell and path enforcement

Block inline pwsh -Command/-c (force .ps1 file approach) and
Windows backslash paths in Bash commands (enforce forward slashes).

Eliminates the 2-3 retry loop on PowerShell operations and prevents
the /tmp path mismatch that caused the stale-payload Syncro incident.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.claude/hooks/pre-bash-backslash.sh

@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+# Pre-tool hook: block Windows backslash paths in Bash commands.
+#
+# Blocks patterns like C:\Users\foo passed inside Bash command strings.
+# Enforces forward slashes: C:/Users/foo
+#
+# Why: Git Bash mangles backslash paths — C:\tmp writes to a different
+# directory than the Write tool's C:\tmp, causing stale payload bugs.
+
+input=$(cat)
+cmd=$(echo "$input" | jq -r '.tool_input.command // ""' 2>/dev/null)
+
+# Match a drive letter followed by a literal backslash in the command.
+# In the extracted command string (not JSON-escaped), backslash is just \.
+if echo "$cmd" | grep -qE '[A-Za-z]:\\[A-Za-z/\\]'; then
+    echo "BLOCKED: Use forward slashes for Windows paths in Bash commands."
+    echo ""
+    echo "  Wrong:   C:\\Users\\guru\\file.txt"
+    echo "  Correct: C:/Users/guru/file.txt"
+    echo ""
+    echo "Git Bash converts backslash paths unpredictably. PowerShell and Windows"
+    echo "APIs both accept forward slashes without issue."
+    exit 2
+fi
+
+exit 0

.claude/hooks/pre-bash-pwsh-script.sh

@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+# Pre-tool hook: block inline PowerShell, enforce .ps1 file approach.
+#
+# Blocks powershell.exe -Command and pwsh -Command / pwsh -c inline execution.
+# Forces: write a .ps1 file, then run pwsh -NoProfile -File script.ps1
+#
+# Why: Git Bash expands $_ and mangles quoting before PowerShell sees the
+# command. Inline execution fails 2-3 times before landing on the .ps1 approach.
+
+input=$(cat)
+cmd=$(echo "$input" | jq -r '.tool_input.command // ""' 2>/dev/null)
+
+# Match: (powershell[.exe] | pwsh) followed by -Command or -c (as a flag, not a filename)
+if echo "$cmd" | grep -qiE '^\s*(powershell(\.exe)?|pwsh)\s+(-Command|-c) ' || \
+   echo "$cmd" | grep -qiE '^\s*(powershell(\.exe)?|pwsh)\s+(-Command|-c)$'; then
+    echo "BLOCKED: Do not use powershell.exe or pwsh with inline -Command/-c arguments."
+    echo ""
+    echo "Git Bash mangles quoting and variable expansion before PowerShell sees the command."
+    echo ""
+    echo "Correct approach:"
+    echo "  1. Write the script using the Write tool to a .ps1 file"
+    echo "  2. Run: pwsh -NoProfile -File \"path/to/script.ps1\""
+    exit 2
+fi
+
+exit 0