rogee/superpowers
1
0
Fork 0
mirror of https://github.com/obra/superpowers.git synced 2026-06-11 13:19:05 +08:00
Code Issues Packages Projects Releases Wiki Activity

Pipe SessionStart hook printf through cat to absorb EPIPE on Windows

Browse Source 
On Windows + Git Bash, the SessionStart hook prints a confusing
diagnostic at every startup ("printf: write error: Permission denied")
when Claude Code closes the hook's stdout pipe before the printf has
finished writing. The hook still runs to completion and context still
gets injected, but the diagnostic surfaces every session because
Git Bash's printf reports EPIPE as "Permission denied" (not "Broken
pipe" like Linux) and our `set -euo pipefail` lets that error escape.

Piping each printf through `cat` makes the external cat process the
recipient of any SIGPIPE / EPIPE. cat's failure does not propagate to
the parent bash under pipefail because cat is the last command in the
pipeline and exits cleanly when the pipe stays open long enough to
hold the data. On macOS/Linux the cat passthrough is transparent (no
behavior change, no measurable cost).

Verified:
- Existing tests/hooks/test-session-start.sh: 7/7 pass on macOS
- Manual run on Windows 11 + Git Bash 5.2 + Node 22 produces valid JSON,
  clean stderr, and exit 0
- JSON output is byte-identical to the unpatched hook

Reported by @silvertakana in #1612, attribution preserved in the
Co-authored-by trailer below — this is the same fix shape the original
PR proposed.

Co-authored-by: silvertakana <silvertakana@users.noreply.github.com>
Closes #1612.
This commit is contained in:
Jesse Vincent
2026-05-23 16:55:46 -07:00
parent 21ad401e90
commit f36bad5b78
2 changed files with 4 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
hooks/session-start
View File

@@ -37,13 +37,13 @@ session_context="<EXTREMELY_IMPORTANT>\nYou have superpowers.\n\n**Below is the
# See: https://github.com/obra/superpowers/issues/571 # See: https://github.com/obra/superpowers/issues/571
if [ -n "${CURSOR_PLUGIN_ROOT:-}" ]; then if [ -n "${CURSOR_PLUGIN_ROOT:-}" ]; then
# Cursor sets CURSOR_PLUGIN_ROOT (may also set CLAUDE_PLUGIN_ROOT) # Cursor sets CURSOR_PLUGIN_ROOT (may also set CLAUDE_PLUGIN_ROOT)
printf '{\n "additional_context": "%s"\n}\n' "$session_context" printf '{\n "additional_context": "%s"\n}\n' "$session_context" | cat
elif [ -n "${CLAUDE_PLUGIN_ROOT:-}" ] && [ -z "${COPILOT_CLI:-}" ]; then elif [ -n "${CLAUDE_PLUGIN_ROOT:-}" ] && [ -z "${COPILOT_CLI:-}" ]; then
# Claude Code sets CLAUDE_PLUGIN_ROOT without COPILOT_CLI # Claude Code sets CLAUDE_PLUGIN_ROOT without COPILOT_CLI
printf '{\n "hookSpecificOutput": {\n "hookEventName": "SessionStart",\n "additionalContext": "%s"\n }\n}\n' "$session_context" printf '{\n "hookSpecificOutput": {\n "hookEventName": "SessionStart",\n "additionalContext": "%s"\n }\n}\n' "$session_context" | cat
else else
# Copilot CLI (sets COPILOT_CLI=1) or unknown platform — SDK standard format # Copilot CLI (sets COPILOT_CLI=1) or unknown platform — SDK standard format
printf '{\n "additionalContext": "%s"\n}\n' "$session_context" printf '{\n "additionalContext": "%s"\n}\n' "$session_context" | cat
fi fi
exit 0 exit 0

2
hooks/session-start-codex
View File

@@ -21,6 +21,6 @@ escape_for_json() {
using_superpowers_escaped=$(escape_for_json "$using_superpowers_content") using_superpowers_escaped=$(escape_for_json "$using_superpowers_content")
session_context="<EXTREMELY_IMPORTANT>\nYou have superpowers.\n\n**Below is the full content of your 'superpowers:using-superpowers' skill - your introduction to using skills. For all other skills, follow the Codex skill-loading instructions in that skill:**\n\n${using_superpowers_escaped}\n</EXTREMELY_IMPORTANT>" session_context="<EXTREMELY_IMPORTANT>\nYou have superpowers.\n\n**Below is the full content of your 'superpowers:using-superpowers' skill - your introduction to using skills. For all other skills, follow the Codex skill-loading instructions in that skill:**\n\n${using_superpowers_escaped}\n</EXTREMELY_IMPORTANT>"
printf '{\n "hookSpecificOutput": {\n "hookEventName": "SessionStart",\n "additionalContext": "%s"\n }\n}\n' "$session_context" printf '{\n "hookSpecificOutput": {\n "hookEventName": "SessionStart",\n "additionalContext": "%s"\n }\n}\n' "$session_context" | cat
exit 0 exit 0